Spindle-shaped magnetic alloy particles containing Fe and Co as main components of the present invention have a cobalt content of 20 to 50 atm % (calculated as Co) based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 xcexcm; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 100 to 160 xc3x85; and an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3. A high-density magnetic recording medium produced by using such spindle-shaped magnetic alloy particles containing Fe and Co as main components, have an excellent output characteristics in a short wavelength region, a considerably reduced noise and an excellent storage stability.

The present invention relates to spindle-shaped magnetic alloy particles for magnetic recording, and a magnetic recording medium, and more particularly, to a high-density magnetic recording medium having an excellent output characteristics in a short wavelength region, a considerably reduced noise and an excellent storage stability; spindle-shaped magnetic alloy particles containing Fe and Co as main components, which are contained in the magnetic recording medium and are fine particles exhibiting not only a high coercive force, an adequate saturation magnetization value and an excellent oxidation stability in spite of a small crystallite size, but also a small rotational hysteresis integral value when formed into a coating film; and a high-density magnetic recording medium having an excellent output characteristics in a short wavelength region, a considerably reduced noise and an excellent storage stability.
With recent development of miniaturized and lightweight magnetic recording and reproducing apparatuses for use in audio, video and computer as well as increase in recording time and memory capacity thereof, magnetic recording media used therefor have increasingly required to have a high performance and a high recording density.
In particular, in the field of computer tapes, with rapid development of high performance computers, it has been strongly required to enhance a memory capacity thereof for achieving miniaturization and large capacity thereof.
Namely, the magnetic recording media have been required to exhibit a high recording density, high output characteristics and improved frequency characteristics, especially excellent output characteristics in a short wavelength region. For this purpose, it has been required to reduce a noise of the magnetic recording media, and enhance a coercive force Hc thereof.
Also, in recent magneto resistive-type head as a reproduction head for computer tapes instead of conventional induction-type magnetic heads. Since the MR head can readily produce a considerably high reproduction output as compared to the conventional induction-type magnetic heads, it has been expected to further improve a high-density recording performance of the magnetic recording media.
In particular, the MR head is free from impedance noise due to use of induction coil and, therefore, is capable of reducing a system noise such as device noise to a large extent, resulting in reduced noise and high C/N ratio of the magnetic recording media. Accordingly, it has been strongly required to further reduce the noise of the magnetic recording media as compared to conventional ones.
In addition, in order to achieve a high-density recording, especially reduce a recording wavelength, it has been required to narrow a magnetization transition region and sharpen a digital signal reproduction waveform from the standpoints of high output and low noise. For this purpose, it has also been desired to approach the magnetization reversal to coherent rotation relative to a magnetic field and lessen the width of magnetization reversal.
These properties of the magnetic recording media have a close relation to magnetic particles used therein. In recent years, magnetic alloy particles containing iron as a main component have been noticed, because such particles can show a high coercive force and a large saturation magnetization ("sgr"s) as compared to those of conventional magnetic iron oxide particles. Further, magnetic alloy particles containing iron as a main component have been already used as magnetic particles for external memory devices such as computer tapes, e.g., DDS, DLT and TRAVAN.
Therefore, it has been strongly required to further improve properties of the magnetic alloy particles containing iron as a main component in order to satisfy the above requirements for magnetic recording media.
Specifically, in order to obtain magnetic recording media having a high coercive force, a less noise and a small width of magnetization reversal, it has been strongly required to provide fine magnetic alloy particles containing iron as a main component which are fine particles and are capable of not only exhibiting a small crystallite size, a high coercive force and an excellent dispersibility, but also having a magnetization reversal mechanism for ensuring substantially coherent rotation of the magnetization relative to a magnetic field.
As to the reduction in particle size of the magnetic alloy particles, in Japanese Patent Application Laid-Open (KOKAI) No. 2000-251243, it is described that xe2x80x9c. . . When the size of a magnetic particles used becomes as large as compatible with a length of a recording region for signals, a clear magnetization transition region is no longer available, so that it becomes substantially impossible to record signals thereon. For this reason, it has been longtime demanded to provide the fine particles for achieving high-density recording upon use . . . xe2x80x9d Thus, in order to obtain magnetic recording media having a high output characteristics in a short wavelength region, and a less noise, it is required to reduce the particle size of the magnetic alloy particles for obtaining fine particles, i.e., reduce the major axis diameter thereof.
Also, as to the crystallite size of the magnetic alloy particles, in Japanese Patent Application Laid-Open (KOKAI) No. 7-126704 (1995), it is described that xe2x80x9c. . . In order to reduce the noise level due to magnetic recording media, it is also effective to reduce the X-ray-measured size to as low a level as possible . . . xe2x80x9d. Thus, in order to obtain magnetic recording media having a less noise, the magnetic alloy particles containing iron as a main component have been strongly required to have a smaller crystallite size D110.
In addition, in order to further reduce the noise of the magnetic recording media, it is insufficient to lessen merely the major axis diameter and crystallite size of the magnetic alloy particles. For this purpose, it has been strongly required to clearly determine what factors should be concerned with the noise to be reduced.
In particular, there has been recently studied the activation volume obtained by measuring a time decay of magnetization due to thermal fluctuation and magnetic after-effect. On the basis of such studies, the reduction in noise of magnetic recording media has been attempted by optimizing the activation volume.
Also, it has been required to approach a magnetization reversal mode of the magnetic alloy particles to coherent rotation.
However, it is very difficult to obtain magnetic alloy particles containing Fe and Co as main components, which are fine particles, and exhibit a small crystallite size, a high coercive force and a magnetization reversal mode close to coherent rotation, because of its production process.
The above fact is explained below.
That is, the magnetic alloy particles containing iron as a main component have been generally produced by heat-reducing in a reducing gas atmosphere (i) spindle-shaped goethite particles obtained by passing an oxygen-containing gas such as air through an aqueous solution containing an iron-containing precipitate produced by reacting an aqueous ferrous salt solution with an aqueous alkali solution to conduct an oxidation reaction thereof, (ii) spindle-shaped hematite particles obtained by heat-dehydrating the spindle-shaped goethite particles, or (iii) spindle-shaped particles obtained by incorporating different elements other than iron into these particles.
As to the relationship between crystallite size and coercive force, in Japanese Patent Application Laid-Open (KOKAI) No. 4-61302 (1992), it is described that xe2x80x9c. . . There is a tendency that the smaller the crystallite size, the lower the coercive force. Therefore, . . . it has been strongly required to provide magnetic particles exhibiting a small crystallite size while maintaining as high a coercive force as possible . . . xe2x80x9d. Thus, in the case of the spindle-shaped magnetic alloy particles, the crystallite size and the coercive force thereof have a reverse interrelation to each other. Therefore, it is extremely difficult to obtain magnetic alloy particles satisfying both a small crystallite size and a high coercive force.
In addition, in the consideration of good oxidation stability of the magnetic alloy particles, it is necessary to fully enhance the reduction percentage of the particles by increasing a heat-reducing temperature to as high a value as possible. However, when the heat-reducing temperature is elevated, the starting particles tend to suffer from shape destruction, resulting in deteriorated coercive force of the obtained magnetic alloy particles. Further, since the heat-reduction conditions such as atmosphere and temperature are very severe, the obtained spindle-shaped magnetic alloy particles tend to suffer from sintering within or between the particles.
In recent years, the particle size of magnetic alloy particles is more and more reduced in order to impart a high coercive force thereto. For this reason, the particle size of the starting particles is also reduced. However, in the case where the starting particles are fine particles having a particle size of not more than 0.15 xcexcm, there is such a remarkable tendency that the particles suffer from shape destruction upon the heat-reduction process. Such shape-destroyed magnetic alloy particles cannot exhibit a high coercive force because of shape anisotropy thereof, and are deteriorated in size distribution. Further, the reduction in particle size of the magnetic alloy particles causes a rapid deterioration in oxidation stability thereof. In addition, when such fine particles are used for the production of magnetic recording media, the dispersibility of the fine particles in vehicles tends to be deteriorated because of the increase in intermolecular force between the particles or the increase in magnetic cohesive force therebetween when kneaded with a binder and dispersed in vehicles. As a result, a magnetic coating film produced from such fine particles is deteriorated in squareness, so that it becomes difficult to obtain magnetic recording media exhibiting an excellent SFD.
Also, although the magnetization reversal mode of the magnetic alloy particles can approach to coherent rotation by enhancing a single crystal growth thereof, there arises a problem that the enhanced single crystal growth also causes increase in crystallite size of the magnetic alloy particles. Therefore, it has been difficult to achieve both the requirements of approaching the magnetization reversal mode of the magnetic alloy particles to coherent rotation, and lessening the crystallite size thereof.
The method of obtaining magnetic recording media exhibiting a high output characteristics and a low noise by improving properties of the magnetic alloy particles has been described in Japanese Patent Application Laid-Open (KOKAI) Nos. 8-171718 (1996), 9-22522 (1997), 9-22523 (1997), 9-106535 (1997) and 10-302243 (1998), etc.
At present, it has been strongly demanded to provide spindle-shaped magnetic alloy particles not only having a high coercive force and an adequate saturation magnetization value in spite of a crystallite size as small as especially not more than 160 xc3x85, but also exhibiting a magnetization reversal mode close to coherent rotation. However, such magnetic alloy particles fully satisfying the aimed properties have not been obtained.
That is, in Japanese Patent Application Laid-Open (KOKAI) No. 8-171718 (1996), although the ratio of coercive force Hc to an anisotropy field HK of a magnetic recording medium is specified therein, it is still insufficient to reduce a noise. In addition, properties of magnetic alloy particles required for reducing the noise, have not been fully studied.
In Japanese Patent Application Laid-Open (KOKAI) Nos. 9-22522 (1997) and 9-22523 (1997), the number of crystallites of magnetic alloy particles is specified, and in Japanese Patent Application Laid-Open (KOKAI) No. 9-106535 (1997), there are specifically described the number of crystallites and crystallinity of magnetic alloy particles as well as the magnetization reversal mode. However, these specified properties of the magnetic alloy particles cannot satisfy the requirement for reducing the noise, and are still insufficient from the standpoint of bringing the magnetization reversal mode into coherent rotation.
Also, in Japanese Patent Application Laid-Open (KOKAI) No. 10-302243 (1998), there is specifically described a magnetization reversal volume of magnetic recording media which is obtained from a frequency-dependence of the coercive force. The specified property is still insufficient to fully reduce the noise. In addition, there are no descriptions concerning properties of magnetic alloy particles required for reducing the noise.
In xe2x80x9cTechnical Report of the Institute of Electronics Information and Communication Engineersxe2x80x9d, MR97-22, pp. 29 to 34 (1997-07), there is described the relationship between activation volume and actual volume of magnetic recording media using magnetic alloy particles. However, since the magnetic recording media have a large activation volume, it is not suitable to fully reduce the noise. In addition, any properties of magnetic alloy particles required for reducing the noise are not fully studied.
Also, in xe2x80x9cJournal of Magnetism and Magnetic Materialsxe2x80x9d, 193, pp. 314 to 317 (1999), there is described the activation volume of magnetic alloy particles. However, since the magnetic alloy particles have a large crystallite size, it is not possible to fully reduce the noise.
As a result of the present inventors"" earnest studies for solving the above problems, it has been found that by heating spindle-shaped goethite particles containing cobalt in an amount of 20 to 50 atm % (calculated as Co) based on whole Fe and having an average major axis diameter of 0.05 to 0.15 xcexcm, or spindle-shaped hematite particles obtained by heat-dehydrating the above spindle-shaped goethite particles as starting particles, to a temperature of 300 to 600xc2x0 C. in an inert gas atmosphere, and after replacing the inert gas atmosphere with a reducing gas atmosphere, heat-reducing the above heat-treated particles at a temperature of 300 to 600xc2x0 C., thereby obtaining spindle-shaped magnetic alloy particles;
subjecting the obtained spindle-shaped magnetic alloy particles to surface oxidation at a temperature of 80 to 200xc2x0 C. in an oxygen-containing inert gas atmosphere, thereby controlling the saturation magnetization value of the spindle-shaped magnetic alloy particles to 85 to 135 Am2/kg;
heating the obtained spindle-shaped magnetic alloy particles to a temperature higher by not less than 50xc2x0 C. than the above heat-reducing temperature which are between 400 to 700xc2x0 C., in an inert gas atmosphere, and after replacing the inert gas atmosphere with a reducing gas atmosphere, heat-reducing the obtained particles again at a temperature of 400 to 700xc2x0 C.; and
subjecting the obtained spindle-shaped magnetic alloy particles again to surface oxidation at a temperature of 40 to 160xc2x0 C. in an inert gas atmosphere containing water vapor in an amount of 5 to 10 g/cm3 and oxygen,
a magnetic recording medium produced using the thus obtained spindle-shaped magnetic alloy particles exhibits not only an excellent output characteristics in a short wavelength region and a considerably reduced noise, but also an excellent storage stability. The present invention has been attained on the basis of this finding.
An object of the present invention is to provide spindle-shaped magnetic alloy particles which are fine particles, and exhibit not only a high coercive force and an adequate saturation magnetization vale in spite of a small crystallite size, but also a small rotational hysteresis integral value.
Another object of the present invention is to provide a high-density magnetic recording medium capable of exhibiting not only an excellent output characteristics in a short wavelength region and a considerably reduced noise, but also an excellent storage stability.
To accomplish the aims, in a first aspect of the present invention, there are provided spindle-shaped magnetic alloy particles containing Fe and Co as main components, having a cobalt content of 20 to 50 atm %, calculated as Co, based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 xcexcm; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 100 to 160 xc3x85; and an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3.
In a second aspect of the present invention, there are provided spindle-shaped magnetic alloy particles containing Fe and Co as main components, having a cobalt content of 20 to 50 atm %, calculated as Co, based on whole Fe; an average major axis diameter (L) of 0.03 to 0.08 xcexcm; an average minor axis diameter of 0.008 to 0.020 xcexcm; an aspect ratio (average major axis diameter/average minor axis diameter) of 3:1 to 8:1; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 110 to 160 xc3x85; and an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3.
In a third aspect of the present invention, there are provided spindle-shaped magnetic alloy particles containing Fe and Co as main components, having a cobalt content of 20 to 50 atm %, calculated as Co, based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 xcexcm; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 100 to 160 xc3x85; an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3; and a rotational hysteresis integral value (Rh) of not more than 1.0.
In a fourth aspect of the present invention, there are provided spindle-shaped magnetic alloy particles containing Fe and Co as main components, having a cobalt content of 20 to 50 atm %, calculated as Co, based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 xcexcm; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a saturation magnetization value of 100 to 150 Am2/kg; a crystallite size of 100 to 160 xc3x85; an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3; and a rotational hysteresis integral value (Rh) of not more than 1.0.
In a fifth aspect of the present invention, there is provided a magnetic recording medium comprising a non-magnetic substrate, and a magnetic layer formed on the non-magnetic substrate, which comprises a binder resin and the spindle-shaped magnetic alloy particles containing Fe and Co as main components, which have a cobalt content of 20 to 50 atm %, calculated as Co, based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 xcexcm; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 100 to 160 xc3x85; and an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3.
In a sixth aspect of the present invention, there is provided a magnetic recording medium comprising a non-magnetic substrate, and a magnetic layer formed on the non-magnetic substrate, which comprises a binder resin and the spindle-shaped magnetic alloy particles containing Fe and Co as main components, which have a cobalt content of 20 to 50 atm %, calculated as Co, based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 xcexcm; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 100 to 160 xc3x85; and an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3,
the magnetic recording medium having a coercive force Hc of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a squareness (Br/Bm) of not less than 0.82; an orientation degree of not less than 2.0; an oxidation stability xcex94Bm of less than 8%; and a surface roughness Ra of not more than 8 nm.
In a seventh aspect of the present invention, there is provided a magnetic recording medium comprising a non-magnetic substrate, and a magnetic layer formed on the non-magnetic substrate, which comprises a binder resin and the spindle-shaped magnetic alloy particles containing Fe and Co as main components, which have a cobalt content of 20 to 50 atm %, calculated as Co, based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 xcexcm; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 100 to 160 xc3x85; and an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3,
said magnetic recording medium having a coercive force Hc of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a squareness (Br/Bm) of not less than 0.82; an orientation degree of not less than 2.0; an oxidation stability xcex94Bm of less than 8%; and a surface roughness Ra of not more than 8 nm.
In an eighth aspect of the present invention, there is provided spindle-shaped magnetic alloy particles containing Fe and Co as main components, having a cobalt content of 20 to 45 atm %, calculated as Co, based on whole Fe; an average major axis diameter (L) of 0.03 to 0.08 xcexcm; an average minor axis diameter of 0.008 to 0.020 xcexcm; an aspect ratio (average major axis diameter/average minor axis diameter) of 3:1 to 8:1; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 110 to 160 xc3x85; and an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3,
the magnetic recording medium having a coercive force Hc of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a squareness (Br/Bm) of not less than 0.82; an orientation degree of not less than 2.0; an oxidation stability xcex94Bm of less than 8%; and a surface roughness Ra of not more than 8 nm.
In a ninth aspect of the present invention, there is provided spindle-shaped magnetic alloy particles containing Fe and Co as main components, having a cobalt content of 20 to 50 atm %, calculated as Co, based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 xcexcm; an average minor axis diameter of 0.008 to 0.020 xcexcm; an aspect ratio (average major axis diameter/average minor axis diameter) of 3:1 to 8:1; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 100 to 160 xc3x85; an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3; and a rotational hysteresis integral value (Rh) of not more than 1.0,
the magnetic recording medium having a coercive force Hc of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a squareness (Br/Bm) of not less than 0.82; an orientation degree of not less than 2.0; an oxidation stability xcex94Bm of less than 8%; and a surface roughness Ra of not more than 8 nm.
In a tenth aspect of the present invention, there is provided spindle-shaped magnetic alloy particles containing Fe and Co as main components, having a cobalt content of 20 to 50 atm %, calculated as Co, based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 xcexcm; an average minor axis diameter of 0.008 to 0.020 xcexcm; an aspect ratio (average major axis diameter/average minor axis diameter) of 3:1 to 8:1; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a saturation magnetization value of 100 to 150 Am2/kg; a crystallite size of 100 to 160 xc3x85; an activation volume (Vact) of 0.01 to 0.07E-4 xcexcm3; and a rotational hysteresis integral value (Rh) of not more than 1.0,
the magnetic recording medium having a coercive force Hc of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a squareness (Br/Bm) of not less than 0.82; an orientation degree of not less than 2.0; an oxidation stability xcex94Bm of less than 8%; and a surface roughness Ra of not more than 8 nm.
The present invention will be described in detail below.
First, the spindle-shaped magnetic alloy particles of the present invention are described.
The spindle-shaped magnetic alloy particles of the present invention contain cobalt in an amount of usually 20 to 50 atm %, preferably 20 to 45 atm % (calculated as Co) based on whole Fe. When the cobalt content is less than 20 atm %, the obtained particles cannot be sufficiently improved in oxidation stability, and can not show a high coercive force. When the cobalt content is more than 50 atm %, the obtained particles are deteriorated in saturation magnetization value and coercive force. In addition, the used of a high cobalt content is also undesirable from economical viewpoint.
The spindle-shaped magnetic alloy particles of the present invention have an average major axis diameter of usually 0.03 to 0.10 xcexcm, preferably 0.03 to 0.095 xcexcm, more preferably 0.03 to 0.08 xcexcm. When the average major axis diameter is less than 0.03 xcexcm, the obtained spindle-shaped magnetic alloy particles suffer from considerable deterioration in saturation magnetization value and oxidation stability, and simultaneously can not show a high coercive force. Further, since the time decay in recording quality due to thermal fluctuation is not ignorable, the obtained particles having such a small average major axis diameter cannot be used as recording media. When the average major axis diameter is more than 0.10 xcexcm, such spindle-shaped magnetic alloy particles can not fully exhibit the aimed high output characteristics in a short wavelength region and a low noise, and are also deteriorated in coercive force.
The spindle-shaped magnetic alloy particles of the present invention have an average minor axis diameter of usually 0.008 to 0.020 xcexcm. When the average minor axis diameter is more than 0.020 xcexcm, the obtained spindle-shaped magnetic alloy particles may be deterioration in coercive force and anisotropy field. Further, it may become difficult to obtain spindle-shaped magnetic alloy particles satisfying all requirements for crystallite size, activation volume and rotational hysteresis integral vale. When the average minor axis diameter is less than 0.008 xcexcm, the obtained spindle-shaped magnetic alloy particles may suffer from considerable deterioration in saturation magnetization value and oxidation stability, and it may be difficult show a high coercive force. Further, since the time decay in recording quality to thermal fluctuation is not ignorable, the obtained particles having such a small average minor axis diameter may not be used as recording media.
The spindle-shaped magnetic alloy particles of the present invention have an aspect ratio (average major axis diameter/average minor axis diameter) of preferably 3:1 to 8:1.
The spindle-shaped magnetic alloy particles of the present invention have a crystallite size D110 of usually 100 to 160 xc3x85, preferably 100 to 155 xc3x85. When the crystallite size D110 is more than 160 xc3x85, the aimed reduction in noise in a short wavelength region may not be sufficiently achieved. When the crystallite size D110 is less than 100 xc3x85, the obtained spindle-shaped magnetic alloy particles may suffer from considerable deterioration in saturation magnetization value and oxidation stability, and simultaneously can not show a high coercive force. Further, since the time decay in recording quality due to thermal fluctuation is not ignorable, the obtained particles having such a small crystallite size may not be used as recording media.
The spindle-shaped magnetic alloy particles of the present invention have an activation volume (Vact) of usually 0.01 to 0.07E-4 xcexcm3, preferably 0.015 to 0.07E-4 xcexcm3. When the activation volume is more than 0.07E-4 xcexcm3, the aimed reduction in noise in a short wavelength region may not be sufficiently achieved. When the activation volume is less than 0.01E-4 xcexcm3, the obtained spindle-shaped magnetic alloy particles may suffer from considerable deterioration in saturation magnetization value and oxidation stability, and simultaneously can not show a high coercive force. Further, since the time decay in recording quality due to thermal fluctuation is not ignorable, the obtained particles having such a small activation volume may not be used as recording media.
The spindle-shaped magnetic alloy particles of the present invention have a rotational hysteresis integral (Rh) value of usually not more than 1.0, preferably not more than 0.95. When the rotational hysteresis integral (Rh) value is more than 1.0, the high output characteristics in a short wavelength region and the reduction in noise may not be achieved.
In addition, the spindle-shaped magnetic alloy particles of the present invention have a BET specific surface area value of preferably 40 to 75 m2/g, more preferably 45 to 75 m2/g. When the BET specific surface area is more than 75 m2/g, it may be difficult to disperse the obtained spindle-shaped magnetic alloy particles in vehicles upon producing a coating material therefrom. When the BET specific surface area is less than 40 m2/g, it is difficult to obtain spindle-shaped magnetic alloy particles capable of satisfying all requirements for crystallite size, activation volume and major axis diameter.
The spindle-shaped magnetic alloy particles of the present invention have a coercive force Hc of usually 159.2 to 238.7 kA/m (2,000 to 3,000 Oe), preferably 167.1 to 222.8 kA/m (2,100 to 2,800 Oe). When the coercive force is more than 238.7 kA/m, the recording head is saturated, thereby failing to obtain the aimed high output characteristics in a short wavelength region. When the coercive force is less than 159.2 kA/m, it is difficult to obtain a fully high output characteristics in a short wavelength region.
The spindle-shaped magnetic alloy particles of the present invention preferably have a saturation magnetization value ("sgr"s) of usually 100 to 150 Am2/kg (100 to 150 emu/g), preferably 100 to 140 Am2/kg (100 to 140 emu/g). When the saturation magnetization value is more than 150 Am2/kg, the increase in noise may be caused. In particular, when an MR head is used as a reproduction head, excessive residual magnetization may be produced, resulting in unnecessary increase in noise and, therefore, deterioration in C/N ratio. When the saturation magnetization value is less than 100 Am2/kg, the obtained magnetic alloy particles may undergo problems such as deteriorated coercive force and wide coercive force distribution.
The spindle-shaped magnetic alloy particles of the present invention have a squareness ("sgr"r/"sgr"s) of 0.52 to 0.55.
The spindle-shaped magnetic alloy particles of the present invention have an anisotropy field (Hk) of usually 477.5 to 636.6 kA/m (6,000 to 8,000 Oe), preferably 517.3 to 636.6 (6,500 to 8,000 Oe). It is difficult to industrially produce such magnetic alloy particles having an anisotropy field (Hk) of more than 636.6 kA/m (8,000 Oe). When the anisotropy field (Hk) is less than 477.5 kA/m (6,000 Oe), it is difficult to attain the aimed high output characteristics in a short wavelength region.
The spindle-shaped magnetic alloy particles of the present invention have an oxidation stability (xcex94"sgr"s) of saturation magnetization of preferably not more than 15%, more preferably not more than 13%, still more preferably not more than 10%.
Next, the process for producing the magnetic recording medium according to the present invention is described.
The magnetic recording medium of the present invention comprises a non-magnetic substrate, and a magnetic recording layer formed on the non-magnetic substrate, which comprises the spindle-shaped magnetic alloy particles of the present invention and a binder resin.
As the non-magnetic substrate, there may be used those presently used in ordinary magnetic recording media, e.g., films of synthetic resins such as polyethylene terephthalate, polyethylene, polypropylene, polycarbonates, polyethylene naphthalate, polyamides, polyamideimides and polyimides, foils and plates of metals such as aluminum and stainless steel, and various papers. The thickness of the non-magnetic substrate may be varied depending upon materials thereof, and is preferably 1.0 to 300 xcexcm, more preferably 2.0 to 50 xcexcm.
More specifically, in the case of magnetic discs, a non-magnetic substrate thereof may be usually made of polyethylene terephthalate, and has a thickness of usually 50 to 300 xcexcm. In the case of magnetic tapes, a non-magnetic substrate thereof may be made of polyethylene terephthalate, polyethylene naphthalate, polyamide or the like; and the polyethylene terephthalate substrate has a thickness of usually 3 to 100 xcexcm; the polyethylene naphthalate substrate has a thickness of usually 3 to 50 xcexcm, and the polyamide substrate has a thickness of usually 2 to 10 xcexcm.
As the binder, there may be used those presently used for the production of ordinary magnetic recording media, e.g., vinyl chloride-vinyl acetate copolymer, urethane resin, vinyl chloride-vinyl acetate-maleic acid copolymer, urethane elastomer, butadiene-acrylonitrile copolymer, polyvinyl butyral, cellulose derivatives such as nitrocellulose, polyester resin, synthetic rubber-based resin such as polybutadiene, epoxy resin, polyamide resin, polyisocyanate, electron beam-curable acrylic urethane resin, or mixtures thereof.
Also, the binder resin may contain polar groups such as xe2x80x94OH, xe2x80x94COOH, xe2x80x94SO3M, xe2x80x94OPO2M2 and xe2x80x94NH2, wherein M represents hydrogen, Na or K.
The magnetic recording layer formed on the non-magnetic substrate has a thickness of usually 0.01 to 5.0 xcexcm. When the thickness is less than 0.01 xcexcm, it may tend to be difficult to form a uniform magnetic recording layer because of coating unevenness or the like. When the thickness is more than 5.0 xcexcm, it may tend to be difficult to obtain the aimed electromagnetic performance because of adverse influence of demagnetizing field.
The amount of the spindle-shaped magnetic alloy particles contained in the magnetic recording layer is usually 5 to 2,000 parts by weight based on 100 parts by weight of the binder resin.
Meanwhile, the magnetic recording layer may further contain, if required, known additives ordinarily used in magnetic recording media such as lubricants, abrasives, anti-static agents or the like in an amount of usually 0.1 to 50 parts by weight based on 100 parts by weight of the binder resin.
The magnetic recording medium obtained using the spindle-shaped magnetic alloy particles according to the present invention exhibits a coercive force Hc of usually 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a squareness (Br/Bm) of usually not less than 0.82, preferably not less than 0.85; an SFD of usually not more than 0.60, preferably not more than 0.50, more preferably not more than 0.45; an orientation degree of usually not less than 2.0, preferably not less than 2.3; an oxidation stability xcex94Bm of usually less than 8%, preferably less than 5%; and a surface roughness Ra of usually not more than 8 nm, preferably not more than 5 nm.
In the magnetic recording medium of the present invention, a non-magnetic undercoat layer containing non-magnetic particles and a binder resin may be disposed between the non-magnetic substrate and the magnetic recording layer.
As the non-magnetic particles for the non-magnetic undercoat layer, there may be used non-magnetic inorganic particles ordinarily used in a non-magnetic undercoat layer of magnetic recording media. Specific examples of the non-magnetic particles may include particles of hematite, iron oxide hydroxide, titanium oxide, zinc oxide, tin oxide, tungsten oxide, silicon dioxide, xcex1-alumina, xcex2-alumina, xcex3-alumina, chromium oxide, cerium oxide, silicon carbide, titanium carbide, silicon nitride, boron nitride, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium sulfate, barium sulfate, molybdenum disulfide, barium titanate or the like. These non-magnetic particles may be used alone or in combination of any two or more thereof. Among these non-magnetic particles, particles of hematite, iron oxide hydroxide and titanium oxide, etc., are preferred.
Upon the production of a non-magnetic coating composition, in order to improve a dispersibility thereof in vehicles, the surface of the non-magnetic particles may be coated, if required, with hydroxides of aluminum, oxides of aluminum, hydroxides of silicon, oxides of silicon or the like. In addition, in order to improve properties of the obtained magnetic recording medium such as light transmittance, surface resistivity, mechanical strength, surface smoothness, durability or the like, various elements such as Al, Ti, Zr, Mn, Sn, Sb, etc., may be incorporated into the non-magnetic particles according to requirements.
The non-magnetic particles may have various shapes, and may include, for example, granular particles such as spherical particles, granulated particles, octahedral particles, hexahedral particles and polyhedral particles; acicular particles such as needle-like particles, spindle-shaped particles and rice ball-shaped particles; plate-shaped particles; or the like. In the consideration of good surface smoothness of the obtained magnetic recording medium, the non-magnetic particles preferably have an acicular particles.
The non-magnetic particles has an average particle diameter of usually 0.01 to 0.3 xcexcm, and may be usually of granular, acicular or plate shape.
The acicular non-magnetic particles have an aspect ratio of usually 2:1 to 20:1, and the plate-shaped non-magnetic particles have a plate ratio (average plate surface diameter/average thickness) of usually 2:1 to 50:1.
The non-magnetic undercoat layer preferably has a thickness of 0.2 to 10.0 xcexcm. When the thickness of the non-magnetic undercoat layer is less than 0.2 xcexcm, it is difficult to improve the surface roughness of the non-magnetic substrate.
As the binder resin for the non-magnetic undercoat layer, there may be used those binder resins exemplified above for the production of the magnetic recording layer.
The amount of the non-magnetic particles contained in the non-magnetic undercoat layer is usually 5 to 2,000 parts by weight based on 100 parts by weight of the binder resin.
Meanwhile, the non-magnetic undercoat layer may further contain, if required, known additives ordinarily used in magnetic recording media such as lubricants, abrasives, anti-static agents or the like in an amount of usually 0.1 to 50 parts by weight based on 100 parts by weight of the binder resin.
In the present invention, the magnetic recording medium having the non-magnetic undercoat layer has the substantially same properties as those of the magnetic recording medium having no non-magnetic undercoat layer as described above. The magnetic recording medium having the non-magnetic undercoat layer according to the present invention can be readily surface-smoothened by calendaring treatment, and can be improved in running durability since a lubricant can be supplied from the non-magnetic undercoat layer.
Next, the process for producing the spindle-shaped magnetic alloy particles according to the present invention is described.
The spindle-shaped magnetic alloy particles of the present invention can be produced from spindle-shaped goethite particles containing cobalt in an amount of usually 20 to 50 atm % (calculated as Co) based on whole Fe and having an average major axis diameter of usually 0.05 to 0.15 xcexcm, or spindle-shaped hematite particles obtained by heat-dehydrating the above spindle-shaped goethite particles as starting particles by the following method. That is, the spindle-shaped magnetic alloy particles of the present invention can be produced by conducting a first step of heating the above starting particles to a temperature of usually 300 to 600xc2x0 C. in an inert gas atmosphere, and after replacing the inert gas atmosphere with a reducing gas atmosphere, heat-reducing the obtained particles at a temperature of usually 300 to 600xc2x0 C., thereby obtaining spindle-shaped magnetic alloy particles; a second step of subjecting the spindle-shaped magnetic alloy particles obtained in the first step to surface oxidation at a temperature of usually 80 to 200xc2x0 C. in an oxygen-containing inert gas atmosphere, thereby controlling the saturation magnetization value of the spindle-shaped magnetic alloy particles to 85 to 135 Am2/kg; a third step of heating the spindle-shaped magnetic alloy particles obtained in the second step to a temperature higher by not less than 50xc2x0 C. than the heat-reducing temperature used in the first step, which are between usually 400 to 700xc2x0 C., in an inert gas atmosphere, and after replacing the inert gas atmosphere with a reducing gas atmosphere, heat-reducing the obtained particles again at a temperature of usually 400 to 700xc2x0 C.; and a fourth step of subjecting the spindle-shaped magnetic alloy particles obtained in the third step again to surface oxidation at a temperature of usually 40 to 160xc2x0 C. in an inert gas atmosphere containing water vapor in an amount of usually 5 to 10 g/m3 and oxygen.
As described above, as the starting particles for spindle-shaped magnetic alloy particles of the present invention, there may be used spindle-shaped goethite particles containing cobalt in an amount of usually 20 to 50 atm % (calculated as Co) based on whole Fe and having an average major axis diameter of usually 0.05 to 0.15 xcexcm, or spindle-shaped hematite particles obtained by heat-dehydrating the above spindle-shaped goethite particles, which contain cobalt in an amount of usually 20 to 50 atm % (calculated as Co) based on whole Fe and have an average major axis diameter of usually 0.05 to 0.13 xcexcm.
The starting particles used in the present invention are spindle-shaped particles containing no dendritic particles and having an excellent size distribution.
The spindle-shaped goethite particles used as the starting particles may be produced from an aqueous ferrous salt solution and an aqueous alkali solution. As alkali contained in such an aqueous alkali solution, there may be used at least one selected from sodium carbonate solution, ammonium hydrogen carbonate solution and a mixed alkali solution composed of ammonium hydrogen carbonate and aqueous ammonia, or a mixed solution composed of the above-mentioned solution and sodium hydroxide solution. In the consideration of a less Na content and good magnetic properties of the obtained spindle-shaped goethite particles, it is preferred to use ammonium hydrogen carbonate and/or aqueous ammonia.
The surface of the spindle-shaped goethite particles used in the present invention may be coated with a Co compound, an Al compound or an anti-sintering agent.
As the anti-sintering agent, there may be used rare earth-containing compounds. Examples of rare earth elements contained in the anti-sintering agent may include scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium or the like. These rare earth elements may be used alone or in combination of two or more thereof. Among these rare earth elements, yttrium is preferred.
In the spindle-shaped goethite particles, in order to further enhance the anti-sintering effect, there may be used, if required, one or more compounds containing other elements selected from Si, B, Mg, Ba, Sr and the like. These compounds have not only the anti-sintering effect, but also a function of controlling the reducing velocity and, therefore, may be used in any suitable combination according to requirements.
In the consideration of anti-sintering effect and well-controlled reducing velocity, the spindle-shaped goethite particles used in the present invention preferably have an average minor axis diameter of 0.010 to 0.024 xcexcm, an aluminum content of 5 to 15 atm % (calculated as Al) based on whole Fe, a rare earth content of 5 to 15 atm % (calculated as rare earth element) based on whole Fe, an aspect ratio of 4:1 to 8:1, and a BET specific surface area value of 100 to 250 m2/g.
Also, in the consideration of anti-sintering effect and well-controlled reducing velocity, the spindle-shaped hematite particles used in the present invention preferably have an average minor axis diameter of 0.010 to 0.023 xcexcm, an aluminum content of 5 to 15 atm % (calculated as Al) based on whole Fe, a rare earth content of 5 to 15 atm % (calculated as rare earth element) based on whole Fe, an aspect ratio (average major axis diameter/average minor axis diameter) of 4:1 to 8:1, and a BET specific surface area value of 50 to 120 m2/g.
The spindle-shaped hematite particles are preferably produced by heat-dehydrating the spindle-shaped goethite particles at a temperature of 150 to 350xc2x0 C. in an oxidative atmosphere, and then heat-treating the obtained particles at a temperature of from more than 450xc2x0 C. to less than 700xc2x0 C. in the same atmosphere.
Further, the thus heat-treated spindle-shaped hematite particles may be washed in order to remove impurity salts such as Na2SO4 derived from the production reaction of the spindle-shaped goethite particles therefrom. In this case, the removal of the impurities is preferably conducted by washing the spindle-shaped hematite particles under such a condition that the anti-sintering agent coated thereon is not eluted out.
In the present invention, when charging into a reducing apparatus, it is preferred to use as starting particles a granular powder having an average diameter of 1 to 5 mm.
As the suitable reducing apparatus used in the present invention, there may be exemplified such a reducing apparatus capable of forming a fixed bed of the particles. More specifically, there may be suitably used a stationary-type (batch-type) reducing apparatus or a movable-type (continuous-type) reducing apparatus capable of reducing the fixed bed formed on a belt while moving the belt.
In the present invention, the height of the fixed bed formed in the reducing apparatus is preferably not more than 30 cm. When the height of the fixed bed is more than 30 cm, there arises such a problem that the particles present in an upper portion of the fixed bed suffer from deterioration in coercive force by increase in water vapor partial pressure therein due to a remarkable reduction-accelerating effect by a large Co content and due to a rapid reduction reaction occurring at a lower portion of the fixed bed, resulting in deteriorated properties of the particles as a whole. In the consideration of industrial productivity, the height of the fixed bed formed in the reducing apparatus is more preferably 3 to 30 cm. Meanwhile, the production efficiency varies depending upon types of the reducing apparatus used, e.g., batch-type reducing apparatuses described in Japanese Patent Application Laid-Open (KOKAI) Nos. 54-62915 (1979) and 4-224609 (1992) or the like are different in production efficiency from continuous-type reducing apparatuses described in Japanese Patent Application Laid-Open (KOKAI) No. 6-93312 (1994) or the like. In the case of the batch-type fixed bed reducing apparatuses, the height of the fixed bed is preferably from more than 8 cm to 30 cm.
In the present invention, the atmosphere used during the heating period in the first and third steps for heating to the heat-reducing temperature is an inert gas atmosphere. As the inert gas for the inert gas atmosphere, there may be suitably used nitrogen gas, helium gas, argon gas or the like. Among these inert gases, nitrogen gas is preferred. When an atmosphere other than the inert gas atmosphere is used, the reduction is prematurely caused during the heating period at which the temperature is changed with the passage of time, so that the reduction temperature cannot be kept constant upon the production of the magnetic alloy particles, thereby failing to achieve a uniform crystallite growth in the particle and obtain particles having a high coercive force.
Meanwhile, the heating velocity in the first and third steps is not particularly restricted, and is preferably 2 to 100xc2x0 C./minute.
The superficial velocity in the inert gas during the heating period of the first and third steps is not particularly restricted, and may be determined so as to prevent the granular starting powder from being scattered or broken.
Also, in the heating of the first and third steps, the method of switching from the inert gas atmosphere to the reducing gas atmosphere for the heat-reduction process, varies depending upon kinds of reducing apparatuses used. From industrial viewpoint, in the case of batch-type reducing apparatus, the switching between the atmospheres is preferably carried out stepwise while controlling an inner pressure of the reducing apparatus, and in the case of continuous-type reducing apparatus, it is preferred that the reducing zone is separated from the heating zone. In any case, the switching between the atmospheres is preferably completed for a short period of time, specifically within 10 minutes.
The atmosphere used in the heat-reducing process of the first and third steps is a reducing gas atmosphere. As the reducing gas, hydrogen may be suitably used.
In the present invention, the heat-reducing temperature used in the first step is usually 300 to 600xc2x0 C., preferably 350 to 550xc2x0 C. The heat-reducing temperature of the first step may be appropriately selected from the above-specified range depending upon kinds and amounts of compounds used for coating of the starting particles. When the heat-reducing temperature is less than 300xc2x0 C., the reduction reaction may proceed very slowly in an industrially-unsuitable manner, so that the obtained spindle-shaped magnetic alloy particles may be deteriorated in saturation magnetization value. When the heat-reducing temperature is more than 600xc2x0 C., the reduction reaction may proceed more rapidly, so that the obtained particles may suffer from shape destruction or sintering within or between the particles, resulting in deteriorated coercive force thereof.
In the present invention, the superficial velocity of the reducing gas used in the first step is preferably 40 to 150 cm/second. When the superficial velocity of the reducing gas used in the first step is less than 40 cm/second, the water vapor produced by reduction of the starting particles may be discharged only too slowly out of the reaction system, so that the particles present in the upper portion of the fixed bed may be deteriorated in coercive force and SFD, thereby failing to obtain particles having a high coercive force as a whole. When the superficial velocity of the reducing gas used in the first step is more than 150 cm/second, although the aimed spindle-shaped magnetic alloy particles are obtained, there may be caused problems such as need of a higher reducing temperature, thereby scattering and breaking of the granulated product or the like.
In the second step of the present invention, the particles obtained in the first step are subjected to surface oxidation in an oxygen-containing inert gas atmosphere. As the inert gas used in the oxygen-containing inert gas atmosphere, nitrogen gas, helium gas, argon gas or the like are preferred. Among these inert gases, nitrogen gas is more preferred. The oxygen content of the oxygen-containing inert gas atmosphere is preferably 0.1 to 5% by volume. It is preferred that the amount of oxygen is gradually increased until reaching the aimed content.
In the present invention, the reaction temperature used in the second step is usually 80 to 200xc2x0 C., preferably 80 to 180xc2x0 C. When the reaction temperature used in the second step is less than 80xc2x0 C., it may be difficult to form a surface-oxidation layer having a sufficient thickness. When the reaction temperature used in the second step is more than 200xc2x0 C., the particles may suffer from change in skeleton thereof, especially extremely swelled minor axis diameter thereof due to the production of a large amount of oxides, resulting in destruction of skeleton of the particles in the worse case.
The spindle-shaped magnetic alloy particles obtained after completion of the second step has a saturation magnetization value of usually 85 to 135 Am2/kg (85 to 135 emu/g), preferably 90 to 130 Am2/kg (90 to 130 emu/g), more preferably 100 to 130 Am2/kg (100 to 130 emu/g). When the saturation magnetization value is less than 85 Am2/kg, the surface-oxidation layer is too thick, so that even though such particles are subjected to the heat-reduction process of the third step, it may be difficult to obtain spindle-shaped magnetic alloy particles having a high coercive force. When the saturation magnetization value is more than 135 Am2/kg, the formation of the surface-oxidation layer is insufficient, thereby failing to form a dense surface-oxidation layer.
Meanwhile, when whole part of the particles is oxidized in the second step, the particles suffer from change in skeleton thereof, especially minor axis growth, i.e., extremely swelled minor axis diameter due to the production of a large amount of oxides. As a result, since the skeleton of such particles is already destroyed, it is not possible to improve a coercive force thereof even by reducing the particles again.
The heat-reducing temperature used in the third step of the present invention is higher by not less than 50xc2x0 C. than the heat-reducing temperature used in the first step, and lies in the range of 400 to 700xc2x0 C. When the heat-reducing temperature used in the third step is not higher by not less than 50xc2x0 C. than the heat-reducing temperature used in the first step, or is less than 400xc2x0 C., the reduction reaction may proceed very slowly in an industrially-unsuitable manner, so that it may be difficult to reduce the surface-oxidation layer formed in the second step, and to densify the particles as a whole. When the heat-reducing temperature used in the third step is more than 700xc2x0 C., the obtained particles may tend to suffer from destruction of skeleton thereof or sintering within or between the particles, resulting in deterioration in coercive force thereof. The heat-reducing temperature used in the third step is preferably in the range of 450 to 650xc2x0 C.
In the present invention, the superficial velocity of the reducing gas used in the third step is preferably 40 to 150 cm/second similarly to the first step.
In the third step, the particles obtained after the reduction process step may be subjected to annealing treatment. The annealing treatment may be conducted at a temperature of preferably 500 to 700xc2x0 C. in a hydrogen gas atmosphere or an inert gas atmosphere such as especially nitrogen.
In the fourth step of the present invention, the particles are surface-oxidized in an inert gas atmosphere containing water vapor in an amount of 5 to 10 g/m3 and oxygen. When the water vapor content in the inert gas atmosphere is less than 5 g/m3, it may be difficult to form a dense and thin surface-oxidation layer, thereby failing to sufficiently improve a coercive force of the particles. When the water vapor content in the inert gas atmosphere is more than 10 g/m3, the effect of addition of water vapor is already saturated and, therefore, the addition of such a large amount of water vapor is unnecessary and meaningless. The water vapor content in the inert gas atmosphere is preferably 2 to 8 g/m3. The oxygen content in the inert gas atmosphere is preferably 0.1 to 5% by volume. It is preferred that the oxygen content in the inert gas atmosphere is gradually increased until reaching the aimed value. The inert gas contained in the above inert gas atmosphere is preferably nitrogen gas, helium gas, argon gas or the like. Among these inert gases, nitrogen gas is more preferred.
The reaction temperature used in the fourth step of the present invention is usually 40 to 160xc2x0 C., preferably 40 to 140xc2x0 C. Meanwhile, it is preferred that the reaction temperature used in the fourth step is lower than the surface-oxidation temperature used in the second step. When the reaction temperature used in the fourth step is less than 40xc2x0 C., it may be difficult to form a satisfactory surface-oxidation layer. When the reaction temperature used in the fourth step is more than 160xc2x0 C., the thickness of the surface-oxidation layer may be too large, resulting in deterioration in saturation magnetization value of the obtained particles.
The point of the present invention is that by using spindle-shaped magnetic alloy particles containing Fe and Co and having a specific crystallite size and a specific activation volume, it is possible to produce a magnetic recording medium having a less noise.
In the above production process of the present invention, the activation volume and the crystallite size of the particles can be controlled to small values by the reduction reaction and surface-oxidation of the first and second steps, and further a dense surface-oxidation layer can be formed by the reduction reaction and surface-oxidation of the third and fourth steps while minimizing the activation volume and the growth of crystallite size. As a result, it is considered by the present inventors that all of requirements including a high coercive force and a small rotational hysteresis integral value as well as a small crystallite size and a small activation volume can be achieved.
In addition, in the present invention, since the activation volume and the crystallite size are controlled to small values, it is possible to reduce the noise. In addition, the small rotational hysteresis integral value causes reduction in width of magnetization reversal, thereby approaching the magnetization reversal mode to coherent rotation. Further, since the spindle-shaped magnetic alloy particles of the present invention are fine particles having a high coercive force and a large anisotropy field, it is possible to obtain a high output performance.
Thus, since the spindle-shaped magnetic alloy particles of the present invention can satisfy various properties as described above, the magnetic recording medium using the spindle-shaped magnetic alloy particles according to the present invention can exhibit not only an excellent output characteristics in a short wavelength region and a considerably reduced noise, but also a small width of magnetization reversal. In addition, the spindle-shaped magnetic alloy particles produced by the above production process according to the present invention are free from sintering therebetween and can be provided thereon with a dense surface-oxidation layer, resulting in excellent dispersibility and oxidation stability. Also, the magnetic recording medium using the spindle-shaped magnetic alloy particles of the present invention is excellent in surface smoothness and long-term storage stability.
The spindle-shaped magnetic alloy particles of the present invention are small in major axis diameter, activation volume and crystallite size, and can exhibit a high coercive force, an excellent oxidation stability and a small rotational hysteresis integral value. Therefore, by using such spindle-shaped magnetic alloy particles, it is possible to produce a high-density magnetic recording medium having a high output performance and a less noise.
Thus, the magnetic recording medium produced using the spindle-shaped magnetic alloy particles of the present invention can be suitably used as a digital magnetic recording medium exhibiting a high-density recording property, high output characteristics and a less noise.

Spindle-shaped magnetic alloy particles for magnetic recording, and magnetic recording medium


The method of removing Escherichia coli (E. coli) bacteria from an aqueous solution includes the step of mixing multi-walled carbon nanotubes functionalized with a dodecylamine group (C12H27N) into an aqueous solution containing E. coli bacteria. The multi-walled carbon nanotubes functionalized with a dodecylamine group have an antimicrobial effect against the E. coli bacteria. The multi-walled carbon nanotubes may be mixed into the aqueous solution at a concentration of between approximately 0.2 g and 0.007 g of multi-walled carbon nanotubes functionalized with a dodecylamine group per 100 ml of the aqueous solution.

1. Field of the Invention
The present invention relates generally to disinfection techniques and methods of treating water or aqueous solution for the removal of microorganisms therefrom, and particularly to a method of removing Escherichia coli (E. coli) bacteria from an aqueous solution using carbon nanotubes functionalized with a dodecylamine group (C12H27N).
2. Description of the Related Art
Escherichia coli (commonly abbreviated E. coli) is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most E. coli strains are harmless, but some, such as serotype O157:H7, can cause serious food poisoning in humans, and are occasionally responsible for product recalls. The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K2 and by preventing the establishment of pathogenic bacteria within the intestine.
Certain strains of E. coli, such as O157:H7, O121 and O104:H21, produce potentially lethal toxins. Food poisoning caused by E. coli is usually caused by eating unwashed vegetables or undercooked meat. O157:H7 is also notorious for causing serious and even life-threatening complications, such as haemolytic-uremic syndrome. This particular strain is linked to the 2006 United States E. coli outbreak due to fresh spinach. Severity of the illness varies considerably. It can be fatal, particularly to young children, the elderly, or the immuno compromised, but is more often mild.
If E. coli bacteria escape the intestinal tract through a perforation (for example from an ulcer, a ruptured appendix, or due to a surgical error) and enter the abdomen, they usually cause peritonitis that can be fatal without prompt treatment. However, E. coli are extremely sensitive to such antibiotics as streptomycin or gentamicin. This, however, could easily change, since E. coli quickly acquires drug resistance. Recent research suggests that treatment with antibiotics does not improve the outcome of the disease, and may, in fact, significantly increase the chance of developing haemolytic-uremic syndrome.
Intestinal mucosa-associated E. coli are also observed in increased numbers in the inflammatory bowel diseases, Crohn's disease, and ulcerative colitis. Invasive strains of E. coli exist in high numbers in the inflamed tissue, and the number of bacteria in the inflamed regions correlates to the severity of the bowel inflammation.
Resistance to beta-lactam antibiotics has become a particular problem in recent decades, as strains of bacteria that produce extended-spectrum beta-lactamases have become more common. These beta-lactamase enzymes make many, if not all, of the penicillins and cephalosporins ineffective as therapy. Extended-spectrum beta-lactamase-producing E. coli are highly resistant to an array of antibiotics, and infections by these strains are difficult to treat. In many instances, only two oral antibiotics and a very limited group of intravenous antibiotics remain effective. In 2009, a gene called New Delhi metallo-beta-lactamase (shortened as NDM-1) that even gives resistance to intravenous antibiotic carbapenem was discovered in India and Pakistan in E. coli bacteria.
Due to the severe nature of E. coli infection and the potential for lethality, it is necessary to develop alternative treatments for E. coli infection and for removal of E. coli bacteria from water and foods. Thus, a method of removing Escherichia coli (E. coli) bacteria from an aqueous solution solving the aforementioned problems is desired.

This patent is subject to a terminal disclaimer.

King Fahd University of Petroleum and Minerals


In an autofocus image sensor, monitoring pixels are disposed adjacent to a pixel array over a length equal to that of the pixel array in each of a standard portion and a reference portion. Signals from the monitoring pixels of both of the standard portion and the reference portion are subjected to arithmetic operation to control accumulation of electric charges. Thus, an error in position detection is minimized.

This invention relates to an image sensor and, in particular, to an autofocus (automatic focus) image sensor of a correlation detection system.
Autofocusing of a correlation detection system uses a special image sensor to realize its function. In the special image sensor, it is required to obtain a uniform output signal in a wide range of brightness from a dark condition at night to a bright condition under sunlight. For this purpose, the special image sensor generally incorporates means for maintaining a constant output signal even in a situation where brightness variation occurs.
In order to detect a varying brightness, use is made of average light amount detecting pixels generally called a monitoring sensor (or monitoring pixels) to control an exposure time (accumulation time) so that electric charges (signals) generated in a pixel array are kept constant. The correlation detection system is a system for detecting a degree of focusing from locations of two images separated by a separator lens. The image sensor compliant with the correlation detection system is provided with two pixel arrays, called a standard portion and a reference portion, respectively, linearly arranged and adapted to read a same image. Since the same image is read, no functional problem is generally caused as long as the monitoring sensor is disposed in the vicinity of one of the pixel arrays.
An example of a conventional structure of the above-mentioned image sensor is shown in FIGS. 1 and 2. FIG. 1 shows a schematic diagram of the image sensor and FIG. 2 shows a block diagram of a signal control portion thereof. The autofocus image sensor comprises a standard portion 7, a reference portion 8, and a signal control portion 6. The standard portion 7 comprises a CCD (charge transferring portion) 1-1, a pixel array charge detector 2-1, a monitoring charge detector 2-3, a pixel array 3-1, average light amount detecting pixels (hereinbelow referred to as monitoring pixels) 4-1, and a control electrode 5-1. The monitoring pixels 4-1 is for use in monitoring an average light amount of the pixel array 3-1. The pixel array charge detector 2-1 is a signal charge detector for detecting signal charges from the pixel array 3-1. The monitoring charge detector 2-3 is a signal charge detector for detecting signal charges from the monitoring pixels 4-1. The control electrode 5-1 controls supply of charges from the pixel array 3-1 to the CCD 1-1. As a result, the control electrode 5-1 controls supply of charges from the pixel array 3-1 to the pixel array charge detector 2-1 connected to an output of the CCD 1-1. The reference portion 8 comprises a CCD 1-2, a pixel array charge detector 2-2, a pixel array 3-2, and a control electrode 5-2. The pixel array charge detector 2-2 is a signal charge detector for detecting signal charges from the pixel array 3-2. The control electrode 5-2 controls supply of charges from the pixel array 3-2 to the CCD 1-2. As a result, the control electrode 5-2 controls supply of charges from the pixel array 3-2 to the pixel array charge detector 2-2 connected to an output of the CCD 1-2. The signal control portion 6 includes a reference voltage generator 13′, a comparator 12′, and an accumulation control signal generating portion 14′.
The signal control portion 6 is controlled by a control signal and the comparator 12′ compares an output from the monitoring charge detector 2-3 of the standard portion 7 with a reference voltage from the reference voltage generator. On the basis of a result of the comparison, the accumulation control signal generating portion 14′ controls the control electrode 5-1 of the standard portion 7 and the control electrode 5-2 of the reference portion 8. However, in order to perform focusing with higher accuracy, it is necessary to control a signal amount into an optimal condition such that a signal (signal charges) of each of the pixel arrays is not saturated. For this purpose, an optimal autofocus image sensor is desired.
Such autofocus image sensor is disclosed in the following patent documents. In Japanese Unexamined Patent Application Publication (JP-A) No. 2005-300844 (corresponding to US2007/098389A1), a standard portion sensor and a reference portion sensor are neighboring in parallel and respective sensor arrays are disposed so as to be relatively deviated from each other. By using the two sensor arrays, signals for focus detection are produced. In Japanese Unexamined Patent Application Publication (JP-A) No. S62-199060, at least two photosensors are provided in the vicinity of a photodiode array. The at least two photosensors produce signals from which a contrast of a subject is detected. Further, Japanese Unexamined Patent Application Publication (JP-A) No. 2001-33687 (corresponding to U.S. Pat. No. 6,445,883B1) discloses a method of reducing focus detection errors by providing a standard portion and a reference portion. Japanese Unexamined Patent Application Publication (JP-A) No. H9-14956 discloses a method of adjusting detection sensitivity.


A system and method are disclosed for monitoring characteristics of a rotating substrate. As the substrate rotates in an environment, an incident light beam is emitted onto the substrate near an axis about which the substrate rotates. The emission of the incident beam is controlled as a function of the angular orientation of the substrate, so that the incident beam selectively interrogates a central region of the substrate to facilitate measuring and/or inspecting characteristics of the substrate.

The present invention relates to semiconductor processing and, more particularly, to a system and method for monitoring characteristics of a rotating substrate.
In the semiconductor industry, there is a continuing trend toward higher device densities. To achieve these higher densities, efforts continue toward scaling down device dimensions (e.g., at sub-micron levels) on semiconductor wafers. To accomplish such high device packing densities, smaller and smaller feature sizes are required. This may include the width and spacing of interconnecting lines, spacing and diameter of contact holes, and the surface geometry such as comers and edges of various features.
The process of manufacturing semiconductors, or integrated circuits, typically consists of more than a hundred steps, during which numerous of copies of an integrated circuit may be formed on a single wafer. Generally, the process involves creating several patterned layers on and into the substrate that ultimately form the complete integrated circuit. Fabricating a semiconductor using such sophisticated manufacturing techniques may involve a series of steps including cleaning, thermal oxidation or deposition, masking, etching, and doping.
Wafers may be pre-cleaned using, for example, high-purity, low-particle chemicals. Silicon wafers may be heated and exposed to ultra-pure oxygen in diffusion furnaces under carefully controlled conditions to form a silicon dioxide film of uniform thickness on the surface of the wafer.
A masking step is utilized to protect one area of the wafer while working on another area. This process typically includes photolithography or photo-masking. A photoresist or light-sensitive film is applied to the wafer, such as while supported in a suitable spin coating apparatus. A photoaligner aligns the wafer to a mask and then projects an intense light through the mask and through a series of reducing lenses, exposing the photoresist with the mask pattern.
The wafer is then xe2x80x9cdevelopedxe2x80x9d (the exposed photoresist is removed), such as by applying a developing solution while rotating the substrate on a suitable support. The developed substrate may then be thermally baked to harden the remaining photoresist pattern. It is then exposed to a chemical solution or plasma (gas discharge) so that areas not covered by the hardened photoresist may be etched away. The photoresist is removed using additional chemicals or plasma. In order to ensure correct image transfer from the mask to the top layer, various wafer inspection methodologies may be employed.
Various process conditions affect formation of layers during semiconductor fabrication. Such conditions further can vary from batch to batch, which variations tend to cause inconsistencies in the resulting products. For example, a non-uniform film thickness can introduce overlay errors and other defects that can adversely affect a resulting integrated circuit formed on the substrate. Accordingly, measurement and inspection systems and techniques have been developed to analyze characteristics of a substrate in between different processing stages. However, when fatal defects are detected after a particular process has completed, structures having such defects typically have to be discarded.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present invention provides a system and method for monitoring characteristics of a substrate. The substrate is supported on a moveable support, such as adapted to rotate about an axis during part of a fabrication process. A measuring system is operable to emit an incident beam onto gratings and/or features of the substrate near the axis about which the substrate is rotating. The beam interacts with the substrate to produce a reflected and/or diffracted beam(s). The reflected and/or diffracted beam can be analyzed to determine substrate characteristics. In order to facilitate measuring feature characteristics, in accordance with an aspect of the present invention, the measuring system emits the incident beam as a function of the rotation of the moveable support such as to interrogate the gratings and/or features at a desired angle relative to the incident beam. As a result, the incident beam is able to selectively interrogate gratings and/or features on the substrate, thereby mitigating errors due to movement of the substrate.
Another aspect of the present invention provides a system for measuring characteristics of a substrate. The system includes a positioning system having a support for receiving a substrate and rotating about a rotational axis. A measurement system includes a light source. When the light source is activated, the light source emits light onto a central region of the substrate based on the angular orientation of the rotating substrate.
Another aspect of the present invention provides a method for measuring characteristics of a substrate. The substrate is rotated about an axis that extends through the substrate while supported within a processing environment. An incident light beam is emitted onto the substrate near the axis. The incident light beam is emitted based on the angular orientation of the substrate. As a result, the incident beam can selectively interrogate the substrate near the axis when the substrate is at a desired angular orientation relative to the incident beam.
To the accomplishment of the foregoing and related ends, certain illustrative aspects of the invention are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed and the present invention is intended to include all such aspects and their equivalents. Other advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.

Scatterometry based measurements of a rotating substrate


A valve includes a body; a liquid flow passage defined in the body and including a liquid inlet and a liquid outlet; a vent passage defined in the body and including an air inlet and an air outlet; a valve seat defined in the liquid flow passage; a liquid seal located adjacent the valve seat; a stem connected to the liquid seal and extending in the liquid flow passage away from the liquid seal through an aperture defined in the body. The stem includes a distal end located external to the body. The stem is movable to and from a first position where the liquid seal is mated with the valve seat and a second position where the liquid seal is unseated from the valve seat. An actuator is connected to the distal end of the stem. The actuator is selectively movable to move the stem from the first position to the second position. A check-valve is adapted to block flow of liquid from the air outlet to the air inlet in the vent passage, and to allow flow of air from the air inlet to the air outlet in said vent passage. The valve optionally further includes a surge control device and/or a keeper for the check-valve seal.

Dispensing liquid from a non-vented rigid container (i.e., sufficiently rigid to resist collapsing when liquid is dispensed) requires that air be vented into the container through the valve to obtain proper flow. Use of a conventional, unvented valve for dispensing liquid will result in liquid flow, if any, that is uneven and insufficient in terms of flow-rate as air must enter the container through the liquid flow passage. Vented valves that allow air to flow into the container are known but have been found to be unsatisfactory for many applications. In some cases, these vented valves rely on use of a vent-tube that extends deep into the container, and these tubes are not suitable for certain applications and also increase cost and are unsightly when visible in the container. Known vented valves are overly complex and, thus, expensive due to material and assembly cost. Also, these known valves often include a seal element that is common to the vent passage and the liquid flow passage and, the simultaneous opening of these passages often results in poor results, especially when dispensing liquid from a pressurized container. In general, known vented valves have been deemed sub-optimal for a wide variety of reasons, and a need has been found for a new vented valve suitable for use in dispensing liquids from pressurized or non-pressurized rigid containers.


A mobile station requests origination of a call and reports signal strength measurements of pilot signals from multiple sectors, where some of the sectors support a preferred air interface configuration (such as RC 11) and some do not. The signal strength measurements may be evaluated to determine which sectors to use for the call and whether to use RC 11 or a default air interface configuration (such as RC 3 or RC 4) for the call. Sectors that support the preferred air interface configuration may be evaluated using a first threshold, and sectors that do not support the preferred air interface configuration may be evaluated using a second threshold. The first threshold can be greater than the second threshold, in order to favor the use of sectors that support the preferred air interface configuration over sectors that do not.

Spread spectrum communications are commonly used in cellular networks that provide wireless service to mobile stations, such as wireless telephones. Cellular networks that use spread spectrum communications often operate in accordance to cdma2000 specifications. The cdma2000 specifications have evolved over time to include various air interface configurations, which are described in the specifications as "Radio Configurations." The specifications define a "Radio Configuration" as follows: "A set of Forward Traffic Channel and Reverse Traffic Channel transmission formats that are characterized by physical layer parameters such as data rates, modulation characteristics, and spreading rate." For example, Radio Configurations 3 and 4 (RC 3 and RC 4) can provide a data rate of up to 9600 bps in a forward fundamental channel, a type of dedicated traffic channel.
Revision E of the cdma2000 physical layer specifications introduced a new air interface configuration, RC 11. Like RC 3 and RC 4, RC 11 can provide a date rate of up to 9600 bps in a forward fundamental channel. However, RC 11 includes several advanced features that can provide capacity and performance benefits. For example, RC 11 can support discontinuous transmission (DTX) service options by including a new 0 bps frame type that can be used during periods of silence. In addition, RC 11 supports frame early termination (FET), which enables a receiver that has successfully decoded a frame before the frame has been completely transmitted to acknowledge receipt and cause further transmission of the frame to be terminated. RC 11 also allows for reduced power control overhead. Further details regarding Revision E can be found in 3rd Generation Partnership Project 2, "Physical Layer Standard for cdma2000 Spread Spectrum Systems: Revision E," 3GPP2 C.S0002-E, Version 2.0, June 2010, which is incorporated herein by reference.

Method and system for channel assignment into soft handoff (casho)


A contact type image sensor device comprises a plurality of photodiodes connected in a matrix, and an equal number of blocking diodes. A capacity ratio of a photo electric part constituting the photodiodes to a diode part constituting the blocking diode is in the range of 2:1 to 30:1. Dynamic range, magnitude of the signal current, light sensitivity and after image characteristics of the image sensor are improved according to the invention.

1. Field of the Invention
This invention relates to a contact type image sensor device which senses an image of objects without reduction of the image. The contact image sensor device is utilized for small-sized facsimile terminal equipment, a bar code reader, and the like.
2. Description of the Related Art
Since a contact image sensor device can sense an image of objects without use of an optical system for reduction of the image, the length of an optical path can be so shortened that equipment comprising the contact image sensor device can be miniaturized. For this reason, recently, contact image sensor devices are widely used as an image sensing unit in small sized facsimile terminal equipment, a bar code reader, and the like.
Though various types of contact image sensor devices are known, the contact image sensor device of the present invention is a type of sensor device which comprises a plurality of photodiodes connected in a matrix and an equal number of blocking diodes provided with each photodiode to prevent a so-called cross talk phenomenon. In this type of contact image sensor device, both the photodiodes and the blocking diodes may be constituted by diodes having the same construction, so that the degree of integration of the sensor elements can be increased and they can be easily fabricated.
U.S. Pat. No. 4,369,372 discloses a photo electro transducer device which comprises n photo electro transducer elements and n diode elements connected respectively to the n photo electro transducer elements. A photo electro transducer element and a respective diode element are formed either on the same side of a common electrode area or formed in layers.
Both the photodiode and the blocking diode have junction capacitances C.sub.p pl and C.sub.b, respectively. The capacitances C.sub.p and C.sub.b are equivalently connected to the photodiode and the blocking diode, respectively, in parallel In order to derive a signal current depending on the brightness of a pixel from each photodiode connected in a matrix, a pulsed voltage is applied to the serially connected photodiode and blocking diode. Accordingly, the values of C.sub.p and C.sub.b, especially the ratio of C.sub.p to C.sub.b, is an important factor in determining a dynamic range, magnitude of the signal current and light sensitivity of the image sensor device. However, these points are not described in the U.S. Pat. No. 4,369,372.

Contact type image sensor device with specific capacitance ratio


In a particular embodiment, parallel deconfliction processing of unmanned aerial vehicles (UAVs) is disclosed that includes a UAV control system partitioning the airspace over a geographic region into a plurality of airspace regions. In this example embodiment, the UAV control system includes a plurality of deconfliction controllers. For each deconfliction controller in the plurality of deconfliction controllers, the UAV control system assigns to the deconfliction controller, one or more airspace regions of the plurality of airspace regions. The UAV control system also inputs, in parallel, flight path data for a plurality of unmanned aerial vehicles (UAVs) to the plurality of deconfliction controllers. This embodiment also includes processing, in parallel by the plurality of deconfliction controllers, the flight path data to identify a flight conflict between two or more UAVs. Each deconfliction controller outputs a deconfliction result for each airspace region.

An Unmanned Aerial Vehicle (UAV) is a term used to describe an aircraft with no pilot on-board the aircraft. The use of UAVs is growing in an unprecedented rate, and it is envisioned that UAVs will become commonly used for package delivery and passenger air taxis. However, as UAVs become more prevalent in the airspace, there is a need to regulate air traffic and ensure the safe navigation of the UAVs.
The Unmanned Aircraft System Traffic Management (UTM) is an initiative sponsored by the Federal Aviation Administration (FAA) to enable multiple beyond visual line-of-sight drone operations at low altitudes (under 400 feet above ground level (AGL)) in airspace where FAA air traffic services are not provided. However, a framework that extends beyond the 400 feet AGL limit is needed. For example, unmanned aircraft that would be used by package delivery services and air taxis may need to travel at altitudes above 400 feet. Such a framework requires technology that will allow the FAA to safely regulate unmanned aircraft.
An important aspect of UAV navigation safety is flight path deconfliction and collision avoidance. As the number of UAVs in the skies increases, so will the difficulty in preventing conflicts among their flight paths, particularly because the flight path of each UAV may change according to the various impediments to navigation (e.g., weather, structures, collision avoidance) that each UAV faces. That is, a change in the flight path of one UAV may have a "butterfly effect" among UAVs in the sky. However, collecting and processing data about UAV flight paths, and resolving conflicting flight paths for collision avoidance, is both a complex and computationally intensive problem.

Parallel deconfliction processing of unmanned aerial vehicles


The object is to provide a slider for fastener fittable to a fastener included in a sealed reclosable bag after the bag is broken and opened, and also easy to fit to as well as remove from a fastener of another bag. The slider includes to first slider member (2) provided with a projection (2A) for disengaging a male engageable member from a female engageable member both included in a fastener (F) and a second slider member (3) provided with a narrowed portion (3C) for fitting the male and female engageable members to each other. The projection (2A) of the first slider member (2) is adapted to be inserted forcibly from outside between the male and female engageable members in an engaged state, and the narrowed portion (3C) in the second slider member (3) is adapted to engage the male and female engageable members with each other. Two protrusions (2E) each provided with a boss (2I) are provided on the first slider member (2) in a manner extending toward the second slider member (3). A hole (3F) is provided in the second slider member (3), into which the protrusions (2E) are fitted in a manner extending out of the hole (3F). Bosses (3L) are provided in the hole (3F), by which the bosses (2I) on the protrusions (2E) are caught.

Many conventional reclosable bags made of synthetic resin film include a fastener (referred to also as zipper). Such a fastener is provided in reclosable bags to prevent the ingress of dust and/or water as well as to prevent articles placed in a reclosable bag from being lost. Most conventional reclosable bags with a fastener are arranged to be unfastened and fastened by opening and closing the fastener by hand or provided with a slider for opening and closing the fastener. That is, in the case of using a slider, a fastener F is provided at a mouth E of a reclosable bag W and an opening/closing slider 10 is fitted to the fastener F, as shown in FIG. 30. Sliding the slider 10 fitted to the fastener F in the direction indicated by the arrow R causes the fastener F to be opened, while sliding in the direction indicated by the arrow S causes the fastener F to be closed.
As shown in FIG. 28(A), such a fastener F typically includes a male engageable member F1 having a projected streak portion F3 and a female engageable member F2 having a recessed engagement groove F4 into which the projected streak portion F3 is fitted engageably and disengageably, the members being provided in an adhesive manner, respectively, on one inner surface W1 and the other inner surface W2 at a mouth E of a bag. When the fastener F of the reclosable bag W is initially closed, the projected streak portion F3 of the male engageable member F1 is fitted in the engagement groove F4 of the female engageable member F2. The mouth E of the reclosable bag W can be opened by inserting the projection 10A of the slider 10 forcibly between the projected streak portion F3 and the engagement groove F4 of the fastener F, as shown in FIG. 28(B), and sliding (moving) the slider 10. The mouth E of the reclosable bag W can be closed by sliding (moving) the slider 10 with the narrowed portion 10C of the slider 10 being placed around the male engageable member F1 and the female engageable member F2, as shown in FIG. 28(C), so that the narrowed portion 10C presses the mouth E of the reclosable bag W on either side thereof.
FIGS. 29(A) and 29(B) are perspective views of the conventional slider 10, respectively, an overall view and view of the slider cut from center. In these figures, for descriptive convenience, the slider is turned upside down (the projection 10A and the narrowed portion 10C are directed upward) contrary to its normal use. As shown in these figures, the conventional slider 10 includes the projection 10A provided in a standing manner within an inner space 10E having a wide central portion nearer one side along its centerline, sidewalls 10D, 10D provided in a standing manner on lateral ends of a bottom portion 10B, and wall portions 10F, 10F constituting the narrowed portion 10C nearer the other side. The slider 10 may be fitted later to the fastener F provided at the mouth E of the reclosable bag W. This arrangement allows the slider 10 to be fitted, as described above, by forcing the projection 10A of the slider 10 downward and placing the narrowed portion 10C around the mouth E of the reclosable bag W. In this state, sliding the slider 10 in the direction indicated by the arrow R (see FIG. 30) allows the fastener F at the mouth E to be opened, while sliding in the direction indicated by the arrow S allows the fastener F at the mouth E to be closed.
Sliders of the type shown in FIG. 30 are most useful, but a little more complex die is necessarily required for manufacturing of such sliders. Hence, the present applicant has proposed such a sectional slider for fastener as shown in FIGS. 26 and 27. That is the slider 31 for fastener includes a slider member 32 formed with a projection 32A for disengaging a male engageable member F1 from a female engageable member F2 both included in a fastener F, the male engageable member F1 having a projected streak portion F3 and the female engageable member F2 having an engagement groove into which the projected streak portion F3 is fitted engageably and disengageably, the members being provided, respectively, on one inner surface and the other inner surface at a mouth of a bag, and another slider member 33 formed with a narrowed portion 33C for fitting the male engageable member F1 into the female engageable member F2. The slider 31 for fastener also has a structure in which the separately-formed slider members 32 and 33 are fitted to each other (refer to Patent Literature 1).
In addition, sidewalls 32C are formed on lateral ends of the slider member 32 having the projection 82A, while columnar portions 33A are formed on either side of the narrowed portion 33C in the slider member 33, and recessed portions 33E are formed on the outer side of the respective columnar portions 33A, whereby the sidewalls 32C can be fitted to the respective recessed portions 33E (refer to Patent Literature 1).
Patent Literature 1: Japanese Patent Application No. 2008-148231


A tug release connector which is opened by tugging on an object being held by a clip. The tug release connector having a hollow body member with a bore therethrough. At one end there is provided a lip surrounding the bore. The lip acts as a catch. An elongate shaft is received by the bore and is spring loaded to partially retract into the hollow body member. The shaft extends from the hollow body member outwardly beyond the lip.. To hold an object, one end of a curved lip is hingedly mounted to the shaft outside the body member. The clip hingedly rotates between a closed position, where a free end of the clip is held by the lip of the body member, and an open position, where the free end is unconstrained from rotating away from the lip. When an object held by the clip is tugged, the shaft extends releasing the free end of the clip from the lip.

This invention relates to an improved tug release connector and more specifically to a tug release connector which is spring-loaded closed and opens to release an object held by the connector when a user tugs on the object.
There are many conventional connectors and snap hooks which have a hinged clip to hold an object. For instance see U.S. Pat. No. 2,276,628 to Quilter, and U.S. Pat. No. 48,275 to Hamilton. These patents illustrate hinged clips that can be opened to accept an object looped about the clip. When the hinged clip is closed, mechanisms are provided to positively hold the clip in a closed position.
There are times when a clip would be more useful if it could be opened with a tug. The device should be easily closed when an object is looped around the clip and in normal use should hold the object securely. Fisherman, for instance, often clip a landing net to their fisherman's vest to keep their hands free. When the use of a landing net is necessary, a fisherman needs to pull the landing net free quickly with one hand, as his other hand is holding a fishing rod with a hooked fish on the line.
In situations such as the above, it can be seen that a need exists for a connector which is simple to operate and one which releases when a user tugs with sufficient force to open the clip.


Pennycress seed, seed lots, and seed meal having reduced fiber content and improved suitability for use in producing animal feed are provided.

Different plants have seed contents that make them desirable for feed compositions. Examples are soybean, canola, rapeseed and sunflower. After crushing the seeds and recovering the oil, the resulting meal has a protein content making the meal useful as a feed ingredient for ruminants, monogastrics, poultry, and aquaculture. Nevertheless, there remains a desire for improved plant seeds that can provide additional sources of nutrition to animals.
Field Pennycress Thlaspi arvense L. (common names: fanweed, stinkweed, field pennycress), hereafter referred to as Pennycress or pennycress, is a winter cover crop that helps to protect soil from erosion, prevent the loss of farm-field nitrogen into water systems, and retain nutrients and residues to improve soil productivity. While it is well established that cover crops provide agronomic and ecological benefits to agriculture and environment, only 5% of farmers today are using them. One reason is economics—it requires on average ˜$30-40/acre to grow a cover crop on the land that is otherwise idle between two seasons of cash crops such as corn and soy. In the last 5 years, it has been recognized that pennycress could be used as a novel cover crop, because in addition to providing cover crop benefits, it is an oilseed with its oil being useful as a biofuel. Extensive testing indicates that it can be interseeded over standing corn in early fall and harvested in spring prior to soybean planting (in appropriate climates). As such, its growth and development requires minimal incremental inputs (e.g., no/minimum tillage, no/low nitrogen, insecticides or herbicides). Pennycress also does not directly compete with existing crops when intercropped for energy production, and the recovered oil and meal can provide an additional source of income for farmers.
Pennycress is a winter annual belonging to the Brassicaceae (mustard) family. It's related to cultivated crops, rapeseed and canola, which are also members of the Brassicaceae family. Pennycress seeds are smaller than canola, but they are also high in oil content. They typically contain 36% oil, which is roughly twice the level found in soybean, and the oil has a very low saturated fat content (˜4%). Pennycress represents a clear opportunity for sustainable optimization of agricultural systems. For example, in the US Midwest, ˜35M acres that remain idle could be planted with pennycress after a corn crop is harvested and before the next soybean crop is planted. Pennycress can serve as an important winter cover crop working within the no/low-till corn and soybean rotation to guard against soil erosion and improve overall field soil nitrogen and pest management.
Pennycress has an oil content that makes it highly desirable as a biofuel, and potentially as a food oil. Once the oil is obtained from pennycress, either from mechanical expeller pressing or hexane extraction, the resulting meal has a high protein level with a favorable amino acid profile that could provide nutritional benefits to animals. However, studies of pennycress processing have consistently demonstrated that the meal produced has a high level of non-digestible fiber, and as a result, not enough metabolizable energy to be competitive with high-value products like soybean and canola meals as an animal feed.

Low fiber pennycress meal, seeds, and methods of making

Board of Trustees of Illinois State University