A pigmented aqueous ink jet ink composition is provided which comprises a sarcosinate compound of the formula:

This invention relates to aqueous pigmented inks for use in ink jet printers.
Ink jet printing is a non-impact method that in response to a digital signal produces droplets of ink that are deposited on a substrate such as paper or transparent film. Ink jet printing has found broad application for output for personal computers in the office and the home as well as in industry. There are several classes of ink jet printer, for instance thermal drop-on-demand printers, piezo drop-on-demand printers, and continuous ink jet printers.
Ink jet printers, particularly those for use in the home or office, generally use aqueous inks, and such inks commonly employ dyes as colorants. However the use of dyes introduces certain disadvantages, particularly the problems of poor light stability and poor fastness to washing and weathering of the prints produced. It is expected that these disadvantages can be overcome by the use of pigments as colorants in ink jet inks, and there is therefore considerable interest in such pigmented inks. The term pigment describes a colorant which is essentially insoluble in the aqueous ink medium. Various classes of pigment are catalogued and classified in the Pigments and Solvent Dyes section of the Colour Index International, published by the Society of Dyers and Colorists in 1997. Many pigments described by the Colour Index are suitable for ink jet use, together with certain compounds classified by the Colour Index as vat or disperse dyes as well as numerous other insoluble coloured compounds which are not included in the Colour Index such as, for example, the cyan pigments described in U.S. Pat. No. 4,311,775 to Regan.
Pigments need to be finely dispersed for use in inks, and this requirement is particularly important for use in jetting inks because of the fine nozzles used in ink jet printers. It is common to formulate dispersions of pigments for use in jetting inks by first dispersing the pigment in a suitable medium, frequently water, in the presence of one or more stabilizers to stabilize and disperse the fine particles, and then letting this dispersion down into the ink with more water, together with organic co-solvents and other additives. The stabilizer used in the dispersion is commonly known as a dispersant or surfactant, and the choice of this component is of crucial importance to the performance of the ink.
It is well known that the choice of dispersant will affect the particle size achieved during the dispersing operation as well as the ease of dispersion. It is also well known that the properties of the ink greatly depend on the stability of the dispersed particles, and the stabilization system is of crucial importance in achieving this. For example, it can be found that particles which are well stabilized in a concentrated dispersion lose this stability when let down into an ink, and that the particles in the ink flocculate or aggregate on storage. This can sometimes be due to simple dilution of the stabilizer, but can also result from interactions with the organic co-solvents or other additives which are commonly present in the final ink. However these co-solvents and other additives need to be present in the ink, either for it to be used successfully in an ink jet printer or to give acceptable properties to the final image. For instance, a major concern with all ink jet printing devices is pluggage of nozzles during operation and between operations, and it is common to add around 10 to 25% of a relatively involatile organic co-solvent or mixture of co-solvents to an aqueous ink to overcome this. Various simple aliphatic polyols, such as glycerol, ethylene glycol, propylene glycol, and diethylene glycol are known to be useful for this purpose. In addition, certain water soluble polymers are also known to be useful, generally in combination with low molecular weight organic cosolvents, and for instance U.S. Pat. No. 5,268,027 to Chan et al. describes the use of alkyl bis polyol ethers as pluggage inhibitors for dyed ink jet inks. However the presence of these additives can adversely affect the dispersion stability of pigmented inks.
It is also known that physical properties of an ink such as surface tension and viscosity which are important for achieving good jettability through an ink jet printer can also depend on the dispersant used in pigmented inks, as can kogation of the heating element for thermal printers. Finally such properties of the final image as density, sharpness, and smudge resistance also depend on the dispersant used.
Several dispersants useful for pigmented aqueous inks are already known. Those most commonly described are acrylic resins which comprise various copolymers of acrylic, methacrylic, or maleic acids, generally in combination with other vinylically unsaturated monomers such as styrene or acrylic esters, such as those described in U.S. Pat. No. 5,085,698 to Ma et al.; U.S. Pat. No. 5,172,133 to Suga et al. and U.S. Pat. No. 5,821,283 to Hesler et al. However with dispersants of this type it can be difficult to achieve the necessary ink stability in the presence of other additives and also to achieve the required viscosity and surface tension without adversely affecting the stability. Various ethoxylated surfactants such as alkyl phenol ethoxylates and alkyl ethoxylates have been described, for example in U.S. Pat. No. 5,837,044 to Santilli et al., but nozzle clogging with pigmented inks can be a problem with this type of dispersant. Simple surfactants, for example sodium dodecyl sulphate and sodium N-methyl-N-oleyl taurate as described in U.S. Pat. No. 5,651,813 to Santilli et al. are also known as dispersants in pigmented jetting inks.
However a need still exists for inks which are highly stable towards aggregation or flocculation on storage, which print successfully through an ink jet printer, and which give good properties to the final image, without introducing other disadvantages. We have found that pigmented ink compositions formulated using various sarcosinate compounds are particularly suitable for ink jet use.
The invention relates to a pigmented aqueous ink jet ink composition which comprises a sarcosinate compound of the formula:
xe2x80x83Rxe2x80x94COxe2x80x94NMexe2x80x94CH2xe2x80x94COOM
In which R is a ballasting group comprising at least ten carbon atoms and M is hydrogen, an alkali metal cation, an ammonium cation or a substituted ammonium cation.
Sarcosinate compounds are well known, and a variety of such compounds are commercially available. They may be prepared from sarcosine, which is an amino acid of natural origin, by acylation with a suitable acylating agent such as an acid chloride of the formula Rxe2x80x94COCl.
Particularly useful sarcosinate compounds are those in which the group R consists of an alkyl chain of between eleven and eighteen atoms. Other useful compounds are those in which the group R consists of an unsaturated alkyl group. It is to be understood that the group R may consist of mixtures of chain lengths or of different isomers in commercially available sarcosinate compounds.
Suitable alkali metal cations include sodium and potassium cations, and suitable substituted ammonium cations include ethanolammonium and triethanolammonium cations.
Specific examples of useful sarcosinate compounds which are commercially available include N-lauroyl sarcosine, N-cocoyl sarcosine, N-stearoyl sarcosine, Sodium N-lauroyl sarcosinate, Potassium N-lauroyl. sarcosinate, Sodium N-palmitoyl sarcosinate, Sodium N-myristoyl sarcosinate, Triethanolammonium N-lauroyl sarcosinate, Triethanolammonium Palm Kernel sarcosinate and Sodium N-oleyl sarcosinate. The oleyl group is an unsaturated alkyl group R and the cocoyl group is one in which the group R comprises a mixture of chain lengths.
The invention relates to pigmented ink jet ink compositions which are particularly suited for use in ink jet printers in general, and thermal ink jet printers in particular. The pigmented inks comprise an aqueous carrier medium, a pigment, and a sarcosinate compound, together with other components which are advantageously added to aqueous inks, such as surfactants, viscosity modifiers, and biocides. In addition, sequestering agents such as EDTA may also be included to eliminate deleterious effects of heavy metal impurities.
Specific examples of pigments for a black ink include carbon black (C.I. Pigment Black 7), such as furnace black, lamp black, acetylene black, and channel black, and o-nitroaniline black (C.I. Pigment Black 1), of which carbon black is preferred. Specific examples of the pigment for a coloured ink include C.I.Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 53, 55, 74, 81, 83, 93, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 128, 138, 151, 153, 154, 155, 180, and 185, C.I. Pigment Orange 5, 13, 16, 17, 34, 36, 43, 51, 70, and 71, C.I. Pigment Red 1, 2, 3, 9, 17, 22, 23, 31, 38, 48:1, 48:2, 48:3, 48:4, 49:1, 52:2, 53:1, 60:1, 63:1, 63:2, 64:1, 81, 83, 88, 104, 105, 106, 112, 114, 122, 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 188, 190, 193, 202, 209, and 219, C.I. Pigment Violet 1, 3, 5:1, 16, 19, 23, and 38, C.I. Pigment Blue 1, 2, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17:1, 56, 60, and 63, and C.I. Pigment Green 1, 4, 7, 8, 10, 17, 18, and 36. Preferred examples of pigments for a coloured ink include Pigment Yellow 13, 74, 128, 151, 154, 155, and 180, Pigment Orange 34, 43, and 71, Pigment Red 122, 202, and 209, Pigment Violet 19, Pigment Blue 15:3, 15:4, and 16, and Pigment Green 7. It is also possible to mix more than one pigment in the inks of the invention.
Many of the above pigments are available commercially in finely divided forms which are specifically aimed at ink jet use. It is preferred to use such available forms in the inks of this invention. It is also possible to use processed pigments such as a graft carbon having a surface treatment.
The sarcosinate compounds are particularly useful as dispersants for pigmented ink jet inks. Therefore according to this preferred aspect of the invention, the ink is prepared by dispersing the pigment or predispersed pigment in the presence of the sarcosinate compound in water, together with optional co-solvents or other components, and then diluting this dispersion to form the ink. The dispersing step may be accomplished using one of several well known techniques, for example in a horizontal mini mill, a ball mill, an attritor, or by passing the mixture through a plurality of nozzles within a liquid jet interaction chamber at a liquid pressure of at least 1000 psi as described in U.S. Pat. No. 5,026,427 to produce a uniform dispersion of the pigment particles. By dilution, the ink is adjusted to the desired viscosity, colour, hue, saturation density, and print area coverage for the particular application.
The particle diameter of the pigment is preferably 10 xcexcm or less, particularly preferably 1 xcexcm or less.
The ink may contain up to approximately 30% pigment by weight, but will generally be in the range of approximately 0.1 to 15%, and is preferably approximately 1 to 8%, by weight of the total ink composition for most thermal ink jet printing applications.
The ink may contain up to 30% of a Sarcosinate compound, but preferably between 0.1% and 10%, and most preferably between about 0.5% and about 2% by weight, depending on the pigment used and other properties desired of the ink.
The aqueous carrier medium is water or a mixture of water and at least one water soluble organic solvent. Deionized water is commonly used. Preferably the aqueous carrier medium is a mixture of water and at least one water soluble organic solvent and most preferably a mixture of water with more than one water soluble organic solvent. Selection of a suitable mixture of water and water soluble organic solvent depends on the requirements of the specific application, such as the selected pigment, the desired surface tension and viscosity, the drying time of the pigmented ink jet ink, and the type of substrate onto which the ink will be printed.
Representative examples of water-soluble organic solvents that may be selected include:
(1) alcohols, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, t-butyl alcohol, iso-butyl alcohol, furfuryl alcohol, and tetrahydrofurfuryl alcohol;
(2) ketones or ketoalcohols such as acetone, methyl ethyl ketone and diacetone alcohol;
(3) ethers, such as tetrahydrofuran and dioxane;
(4) esters, such as ethyl lactate;
(5) polyhydric alcohols, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, tetraethylene glycol, polyethylene glycol, glycerol, 2-methyl-2, 4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,2,6-hexanetriol and thiodiglycol;
(6) lower alkyl mono-or di-ethers derived from alkylene glycols, such as ethylene glycol monomethyl (or -ethyl) ether, diethylene glycol mono-methyl (or -ethyl) ether, propylene glycol mono-methyl (or -ethyl) ether, triethylene glycol mono-methyl (or -ethyl) ether and diethylene glycol di-methyl (or -ethyl) ether;
(7) nitrogen containing organic compounds such as urea, pyrrolidone, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone; and
(8) sulphur-containing compounds such as dimethyl sulphoxide and tetramethylene sulfone.
A preferred aqueous carrier medium is a mixture of water and at least one polyhydric alcohol such as diethylene glycol. Another preferred aqueous carrier medium is a mixture of water with at least one polyhydric alcohol together with at least one water soluble nitrogen containing compound such as urea or pyrrolidone. The aqueous composition may contain up to 50% of the organic cosolvent or cosolvents, but preferably up to about 10% of each of a mixture of organic cosolvents, and most preferably between about 5% and about 10% of each of a mixture of organic cosolvents.

Abstract: Preferably the ink is prepared by dispersing the pigment in the presence of the sarcosinate compound in water, together with optional co-solvents or other components, and then diluting this dispersion to form the ink.


An ultrasonic scanner has a housing, an ultrasonic transducer mounted within the housing for back-and-forth motion about a pivot, a permanent magnet affixed to the rear of the transducer, and electromagnetic means to effect movement of the transducer/magnet assembly. The electromagnetic means comprises two or more longitudinally mounted electromagnets, and optionally two radially mounted permanent magnets which serve as decelerating buffers. Electrical means are provided for energizing the transducer and receiving signals therefrom. Digitizing means are provided to convert the received signals to digital form. Sequential control means are provided to energize the electromagnet coils in a programmed sequence, and furthermore to synchronize transducer motion, periodic energization of the transducer, and digitization of signals received from the transducer. Display means are provided to present the signals received by the transducer to an operator, in the form of a time-varying tomographic image. More generally, a scanning device is provided having electromagnets co-acting with a permanent magnet mounted on a rocker, and coupled with a source and detector for high energy signals, so that a sweeping motion of the rocker can be effected, and an image of the target tissue may be reconstructed.

Ultrasonic imaging, also called echography or B-mode ("brightness mode") ultrasound, involves use of an ultrasonic transducer which repeatedly emits pulses of high-frequency sound and receives the resulting echo signals. A focused beam of sound is normally used, and various means are employed to sweep this beam repeatedly through a range of directions. Electronic processing of the received echo signals, synchronized to the movement of the beam, results in formation of a video image (normally cross-sectional) of structures (such as human tissue) in the beam's path.
For clarity of exposition, the following discussion refers specifically to the medical diagnostic imaging situation in which the target of the ultrasonic imaging system is tissue in a living human patient. It should be realized that ultrasonic scanning is also used in other applications including non-human (veterinary or in vitro tissue sample) biological imaging, and also non-biological imaging applications (non-destructive materials testing), and that the present invention applies without limitation to all such ultrasonic imaging applications.
In ultrasonic scanners for medical diagnostic imaging, the transducer and beam-sweeping components are normally assembled in the form of a hand-held probe connected to the rest of the imaging system by means of a cable. In the following, the term "probe" will be used generically to refer to the transducer and beam-scanning assembly, though it should be realized that not all ultrasonic scanning systems will have or need a physically distinct probe component.
Because the sound frequencies used in ultrasonic imaging are effectively blocked by air, it is necessary to acoustically couple the transducer to the target under investigation via one or more acoustically conductive media. Coupling media must be chosen carefully, to ensure that the effects of sound reflection and refraction occurring at media interfaces do not unduly compromise the imaging capabilities of the system. In practice, the problem of coupling is addressed in one of three ways:
1. Liquid bath. The transducer and target are immersed in a liquid coupling medium such as water or sterile saline solution. This technique is rarely used in clinical scanning applications. PA1 2. Sealed transducer chamber. The transducer is sealed within a liquid-filled chamber within the probe, with a solid "acoustic window" through which the imaging beam can pass. PA1 3. Acoustic coupling gel. Several water-based gel media are now on the market, which provide a convenient means to couple a probe's acoustic window to the surface of target tissue.
Many techniques for sweeping the sound beam are known, but as at the date of filing of this application, there are two main approaches which are in common use. In the mechanical sector-scan approach, a transducer is mechanically oscillated about a pivot, causing the sound beam to sweep through a sector. Acoustic coupling to target tissue may be achieved either by method 1 above, or more commonly, a combination of methods 2 and 3. In the electronic transducer array approach, a fixed array of multiple transducer elements is used, and the sound beam is formed, focused, and swept entirely electronically. Because there is no transducer movement, coupling method 2 above is unnecessary; method 3 alone is sufficient.
The electronic transducer array approach generally provides greater speed, precision and repeatability of sound beam motion than the mechanical sector-scan approach, and hence today the array approach is widely used. However, the array approach, which requires one signal processing channel (e.g. impedance matching and filtering, signal conditioning and amplification, and sometimes digitization) per array element, is inherently more expensive than the mechanical sector scanning approach, and so the mechanical sector scanning approach is still used. In the field of ophthalmology, for example, mechanical sector scanners are still used exclusively. There thus remains a need to advance the state of the art with respect to the mechanical sector scan approach.
So-called annular array transducers, which consist of a small number of concentric ring-shaped transduction elements, may be used in place of a single-element transducer in a mechanical sector scanning apparatus. These devices permit electronic control of sound beam focusing, but not direction. Because the number of transduction elements is small (e.g. three to eight), the cost premium associated with annular array transducers is slight compared with that of a fall electronic array beam sweeping system.
In this application, the term "transducer" refers equally to either a single element transducer or an annular array transducer.
Ultrasonic scanning and image formation can occur quite rapidly, which makes possible dynamic imaging in the presence of motion, e.g. of the living fetus in utero, of the tissues in the eye, or in the course of interventional medical procedures such as catheterization or laparoscopic surgery. The fidelity with which continuous motion can be represented in the live ultrasonic image depends primarily on how rapidly the sound beam can be scanned across the field of view, and on how precisely and repeatably the scanning motion can be controlled.
Purely mechanical means of oscillation, with or without use of magnetic elements on some of the moving members to transfer force across a gap, exhibits a number of disadvantages. The mechanical drive assembly adds substantially to the size and weight of the imaging probe, and to achieve precisely controlled motion it is necessary to augment the mechanical system with a positional sensor and to employ closed-loop feedback control methods in the control system. Addition of the positional sensor adds yet further to the size, weight, and complexity of the probe, while the need for closed loop feedback control adds to the complexity of the control system.
However, motive force may also be applied by means of magnetic forces established between fixed electromagnets, energized with time-varying electric current, and a single permanent magnet affixed to a rotating transducer assembly. Generally, in all of these cases the magnetic oscillator mechanism follows the general principle of a galvanometer, i.e., a magnetic field is established in a fixed stator member, with the magnetization vector substantially at right angles to that of a permanent magnet affixed to a pivoted rocker member. The magnet in the rocker is thus subjected to magnetic torque forces which cause it, and the rocker, to tilt or rotate so as to reduce the angle between the two magnetic vectors. Periodically reversing the direction of the stator field, by passing an alternating current through the one or more electromagnet coils in the stator assembly, thus results in a periodically reversing torque applied to the rocker, and in consequence causes the rocker to oscillate.
In practice, such galvanometer-like mechanisms cannot transfer appreciable amounts of mechanical energy, because of the inverse square relationship between magnetic force and distance. As the rocker magnet tilts away from the center position, it moves further from the stator magnet poles, dramatically reducing the torque efficiency of the system and making it harder to apply the reverse torque required to tilt the rocker back in the opposite direction. Such a system is rather like a heavy weight balanced atop a rod held in the hand; provided the rod does not tip very far from the vertical, small movements of the hand suffice to keep it stably aloft, but the range of controllable motion is very small.
The present invention solves the torque efficiency problems by using a system of many digitally switched stator electromagnet coils, which permit periodic alteration of the magnetic field vector while maintaining a small and little-varying gap between the currently active stator poles and a permanent magnet in the rocker, and furthermore solves the problem of stability at higher operating speeds by providing additional permanent magnets affixed to the stator near the extremes of the rocker's oscillatory motion, oriented so as to repel the permanent magnet in the rocker, causing it to spring back in the opposite direction.

High speed sector scanning apparatus having digital electronic control


Various circuit breaker accessories, such as a shunt trip, an undervoltage release, an auxiliary switch, and a bell alarm, are individually packaged in a standardized molded insulative accessory case for ultimate factory or even field installation in a molded case, automatic power circuit breaker.

The present invention relates to automatic power circuit breaker accessories and particularly to a universal packaging arrangement for the various types of accessory devices commonly utilized in power circuit breakers.
As electrical power distribution systems become more sophisticated, increasing demands are being placed on power circuit breakers to perform collateral functions in addition to their primay function of circuit protection. To this end, circuit breakers are equipped with a wide variety of accessory devices to accommodate these collateral functions. Thus, shunt trips are installed in power circuit breakers to accommodate tripping of the breaker from a remote location initiated manually or automatically in response to a condition not necessarily related to the currents flowing in the breaker poles. Accessory switches are installed in power circuit breakers to sense when the breaker is closed or open, and if open, whether it was manually opened or tripped open. The contacts of these accessory switches are wired into external circuits to effect indicating and control functions. To protect loads such as motors from possible damage due to low line voltage, circuit breakers are equipped with undervoltage releases (UVR) to trip the breaker in response to prolong low line voltage conditions.
In many installations, circuit breakers may be equipped with not one, but several of these accessory device. Particularly in the case of molded case power circuit breakers, the space available to accommodate these accessory devices is at a premium. Moreover, in the close confines of a molded circuit breaker case, isolating the accessory devices from live breaker parts is a signficant problem. For these reasons, plus the fact that the accessories are typically of different sizes and shapes calling for unique mounting provisions, circuit breaker accessories have traditionally been factory installed items. Thus installation of these accessory devices to add their collateral functions to circuit breakers in the field is typically not convenient and, in many instances, not UL approved.
It is accordingly an object of the present invention to provide a family of improved circuit breaker accessory devices.
A further object is to provide accessory devices of the above character wherein each accessory type is packaged in a standardized manner to greatly simplify their installation in power circuit breakers, both in the factory and in the field.
Yet another object is to provide accessory devices of the above character wherein each accessory type is packaged in a standardized insulative, molded case.
An additional object is to provide a family of molded case accessory devices of the above character which are uniformly compact in size, economical to fabricate and assemble, and reliable in operation.
Other objects of the invention will in part be obvious and in part appear hereinafter.

Circuit breaker accessories packaged in a standardized molded case


An apparatus and method is presented for a DRAM memory cell array exhibiting improved alignment tolerance for bit line contact formation and utilizing closely-spaced double-sided stacked capacitors for increased overall feature density on the circuit die. The use of a sacrificial insulating layer, an etch-stop insulating layer, and insulating spacers surrounding the bit line contact plug permits wet etching of the sacrificial layer to enable double-sided capacitors to be formed close together. In the resulting structure, only the bit line contact plug and insulating sidewall spacers separates adjacent capacitors and hence DRAM cells can be more tightly packed on the circuit die. Another aspect of the invention is improved alignment tolerance of the bit line contact plug. Because the bit line contact plug is formed prior to the double-sided capacitors, and then the double sided capacitors are formed to occupy all of the space laterally surrounding the bit line contact plug and its insulating spacers, mask alignment errors are less likely to affect this arrangement.

1. Field of The Invention
The present invention relates to the field of integrated circuits and, more particularly, to an apparatus and method of forming a DRAM cell array with a reduced overall stack height and better alignment tolerance between DRAM container cells and bit line contacts.
2. Description of The Related Art
Modern integrated circuit designers often must confront and solve the problem of space limitations on the circuit die. Because the use and popularity of memory devices, such as dynamic random access memory (DRAM) circuits, has expanded dramatically in recent years, memory circuit manufacturers have been under pressure to increase memory capacity and performance without increasing the space occupied by the circuit.
For example, DRAM memory circuits are manufactured by replicating millions of identical circuit elements, known as DRAM cells, on a single semiconductor wafer. A DRAM cell is an addressable location that can store one bit (binary digit) of data. In its most common form, a DRAM cell consists of two circuit components: a storage capacitor and an access field effect transistor.
FIG. 10 illustrates a portion of a DRAM memory circuit containing two neighboring DRAM cells 100. For each cell, one plate of the storage capacitor 140 is connected to a reference voltage and the other plate is connected to the drain of the access field effect transistor 120. The gate of the access field effect transistor 120 is connected to the word line 180. The source of the field effect transistor 120 is connected to the bit line 160. The word line thus controls access to the storage capacitor 140 by allowing or preventing the logic signal (xe2x80x9c0xe2x80x9d or xe2x80x9c1xe2x80x9d) on the bit line 160 to be written to or read from the storage capacitor 140.
The manufacturing of a DRAM cell includes the fabrication of a transistor, a capacitor, and contacts to the bit line, the word line, and the reference voltage. DRAM manufacturing is a highly competitive business. There is continuous pressure to decrease the size of individual cells and increase memory cell density to allow more memory to be squeezed onto a single memory chip. However, it is necessary to maintain a sufficiently high storage capacitance to maintain a charge at the refresh rates currently in use even as cell size continues to shrink. This requirement has led DRAM manufacturers to turn to three dimensional capacitor designs, including stacked capacitors. Stacked capacitors are capacitors which are stacked, or placed, over the access transistor in a semiconductor device. For reasons including ease of fabrication and increased capacitance) most manufacturers of DRAMs larger than 4 Megabits use stacked capacitors. Therefore, the invention will be discussed in connection with stacked capacitors but should not be understood to be limited thereto. For example, use of the invention in trench or planar capacitors is also possible.
One widely used type of stacked capacitor is known as a container capacitor, shown in FIG. 11. One embodiment of a container capacitor is shaped like an upstanding tube (cylinder) having an oval or circular cross section. FIG. 11 illustrates a top view of a portion of a DRAM memory circuit from which the upper layers have been removed to reveal container capacitors 114 arranged around a bit line contact 62. Six container capacitors are shown in FIG. 11, each of which has been labeled with separate reference designations A to F.
To increase density, the bit line contact 62 is shared by neighboring container capacitors 114, including those labeled A and B. The wall of each container capacitor consists of two plates 82, 94 of conductive material such as doped polycrystalline silicon (referred to herein as polysilicon or poly) separated by a dielectric layer 92. The bottom end of the tube is closed, with the inner wall (lower plate 82) in contact with either the drain of the access transistor or a plug which itself is in contact with the drain. The other end of the tube is open (the tube is filled with an insulative material 102 later in the fabrication process). The sidewall and closed end of the tube form a container; hence the name xe2x80x9ccontainer capacitor.xe2x80x9d
The container capacitors in FIG. 11 are double-sided, meaning the lower plate 82 is surrounded on two sides by the upper plate 94, which is connected to a reference voltage on the periphery (not shown). The use of double-sided capacitors further increases the storage capacitance of the DRAM memory cell, reducing the required depth of the container, but their use requires more lateral space for the second side of the upper plate. Lateral space is at a premium due to the need to increase circuit density while preserving isolation of the capacitor plates from the bit line contact. It would be desirable to develop a technique which improves alignment tolerance of the bit line contacts so that double-sided container capacitors could be squeezed closer together.
Additional space savings on the circuit die are required in order to satisfy the demand on DRAM manufacturers for increased capacity memory circuits. In order to remain competitive, DRAM manufacturers need a circuit design that conserves space on the circuit die but does not require unusually expensive or unconventional processing techniques. Therefore, there is a strong need for an increased-density stacked capacitor memory array design exhibiting improved alignment tolerance, utilizing three-dimensional double-sided capacitors and capable of formation by conventional wafer processing and manufacturing techniques.
The present invention provides an apparatus and method of forming a DRAM memory cell array exhibiting improved alignment tolerance for bit line contact formation and utilizing closely-spaced double-sided stacked capacitors for increased overall feature density on the circuit die.
The above and other features and advantages of the invention are achieved by providing an apparatus and associated method of forming a semiconductor device including:
(a) forming an insulating layer on a semiconductor assembly composed of a plurality of gates and a plurality of conductive plugs formed between the gates;
(b) etching a plurality of holes or contact openings in the insulating layer to expose only selected plugs (xe2x80x98bit-line plugsxe2x80x99);
(c) forming insulating spacers on the sidewalls of the contact openings;
(d) forming conductive bit line contact plugs in the contact openings between the insulating spacers;
(e) etching additional contact openings in the insulating layer laterally adjacent the bit line contact plugs and forming double-sided capacitors in the additional contact openings, removing the remainder of the insulating layer with wet etch techniques during capacitor formation; and
(f) forming a conductive bit line in contact with the bit line contact plugs.
In the present invention, the use of insulating spacers surrounding the bit line contact plug, and a wet etch that selectively stops at those spacers, permits the double-sided capacitors to be formed close together. Only the previously-formed bit line plug and insulating sidewall spacers separates adjacent capacitors from the bit line contact and hence DRAM cells can be more tightly packed on the circuit die.
Another aspect of the invention is improved alignment tolerance of the bit line contact plug. Because the bit line contact plug is formed prior to the double-sided capacitors, and then the double sided capacitors are formed to occupy all of the space laterally surrounding the bit line contact plug and its insulating spacers, mask alignment errors that plagued prior art devices (with after-formed bit line contact plugs) are less likely to affect this arrangement.
The apparatus of the invention includes a plurality of gates and a plurality of closely-spaced container capacitors formed above contact plugs formed between the gates. The container capacitors are separated by a bit line contact plug and an insulating spacer surrounding the plug. The apparatus is formed to permit close spacing of the container capacitors relative to each other, wherein only an insulating spacer separates the contact plug from a container capacitor on either side of the plug.
Furthermore, the present invention provides these and other advantages solely using processing techniques conventionally employed in the manufacture of semiconductor devices. No unusually expensive or cumbersome steps are required in the method of the present invention, resulting in improved device performance without substantially increased cost.

Double sided container capacitor for DRAM cell array and method of forming same


A trouble determining apparatus for a chopper type DC boosting circuit capable of determining whether or not a switching device is in trouble securely and quickly and when the switching circuit is in trouble, preventing other circuit from being in a trouble. Upon determining a short-circuit trouble of a transistor Q, a boosting circuit control unit 22 is turned OFF a power relay RL and then determines whether or not a voltage VP1 of a connecting point P1 rises over a first set voltage VS1 by the time when a first predetermined time t1 elapses since an ignition switch IG is turned ON with the transistor Q set to OFF. Upon determining an open trouble of the transistor Q, the boosting circuit control unit 22 determines whether or not the voltage VP1 of the connecting point P1 falls below a second set voltage by the time when a second predetermined time t2 elapses since the transistor Q is turned ON with the power relay RL set to OFF and whether or not the voltage VP1 falls from a state before the transistor Q is turned ON by more than a third set voltage.

1. Field of the Invention
The present invention relates to a trouble determining apparatus for DC boosting circuit and more particularly to an apparatus for determining a trouble in a switching device of a chopper type DC boosting circuit.
2. Description of the Related Art
Conventionally, the chopper type DC boosting circuit has been widely used in which by turning ON/OFF a current flowing through a boosting coil from a DC power supply with the switching device, back electromotive force generated in a boosting coil is accumulated in a smoothing capacitor through a rectifying diode so as to boost the voltage of the DC power supply. In an electric power steering apparatus for assisting an operation of the power steering wheel using a rotation of an electric motor, for example, there has been proposed such a technology that by boosting the DC voltage of a vehicle loaded battery by means of the chopper type DC boosting circuit and then supplying that boosted voltage to the electric motor to drive the same motor, the amount of current supplied to that electric motor is reduced thereby achieving reductions in capacity of used wires (reducing the diameter of the wire) and size of the electric motor. The applicant of this application invented a chopper type DC boosting circuit suitable for such an electric power steering apparatus (see patent document 1).
[Prior Art]
JP 2003-89360 A (Page 9, FIG. 4) is incorporated herein by reference.
(Configuration of Conventional Chopper Type DC Boosting Circuit)
FIG. 4 is a circuit diagram showing a conventional chopper type DC boosting circuit 60 used in the electric power steering apparatus. The electronic control unit (ECU) 50 of the electric power steering system (EPS) includes a chopper type DC boosting circuit 60. The conventional chopper type DC boosting circuit 60 comprises a power relay RL, a smoothing capacitor C1, a noise filter capacitor C2, a boosting coil L, a transistor Q, a rectifying diode D and a boosting circuit control unit 62. The positive terminal of the vehicle loaded battery B is connected to the ECU 50 through a fuse F while the grounding terminal of the ECU 50 is connected to the negative terminal of the vehicle loaded battery B. The transistor Q which is a switching device is composed of N-channel power metal oxide semiconductor field effect transistor (MOS FET). As the power relay RL, it is permissible to use any one of an electromagnetic relay using an electric magnet and a non-contact relay using a semiconductor switch.
(Switching Device Trouble Determination in a Conventional Chopper Type DC Boosting Circuit)
If in the conventional chopper type DC boosting circuit 60, the transistor Q which is a switching device is in trouble, normal boosting operation is disabled. Thus, the trouble determination in the transistor Q is necessary. For the reason, the boosting circuit control unit 62 has a function for determining a trouble in the transistor Q. The troubles in the transistor Q include open trouble and short-circuit trouble. The open trouble refers to a trouble that a state between the source and drain turns open regardless of a gate voltage (even if a high level driving signal is applied to the gate in order to turn ON the transistor Q which is a N channel, the transistor Q keeps OFF). The short-circuit trouble is a trouble that a short-circuit occurs between the source and drain regardless of the gate voltage (even if a low-level driving signal is applied to the gate in order to turn the transistor Q of the N channel OFF, the transistor Q keeps ON).
(Determining Operation for Short-circuit Trouble)
The boosting circuit control unit 62 executes the determination operation on a short-circuit trouble of the transistor Q before starting the boosting operation by turning ON/OFF the transistor Q. That is, the boosting circuit control unit 62 first is turned ON the power relay RL and at the same time, is turned OFF the transistor Q and next detects a voltage VP1 at a connecting point P1. The boosting circuit control unit 62, if the voltage VP1 is less than a reference voltage VSa, determines that a short-circuit trouble occurs in the transistor Q and if the voltage VP1 is over the reference voltage VSa, determines that the transistor Q is not in short-circuit trouble. That is, if the transistor Q is in the short-circuit trouble, the voltage VP1 of the connecting point P1 is determined by the voltage VB of the vehicle loaded battery B, a resistance of the fuse F, a DC resistance of the boosting coil L and an ON resistance of the transistor Q, because the connecting point P1 is grounded through the boosting coil L and the transistor Q. Then, if the voltage VP1 in the case where the short-circuit trouble occurs in the transistor Q is experimentally obtained and the reference voltage VSa is set to that obtained voltage VP1, the short-circuit trouble of the transistor Q can be determined.
(Determining Operation of the Open Trouble)
After the boosting operation is started by turning ON/OFF the transistor Q, the boosting circuit control unit 62 executes the determining operation upon the open trouble of the transistor Q. That is, the boosting circuit control unit 62 first is turned ON the power relay RL and executes the boosting operation by repeating the ON/OFF operation of the transistor Q, and after that, detects an output voltage VO. If the output voltage VO is equal to the voltage VB of the vehicle loaded battery B and no boosting is carried out, the boosting circuit control unit 62 determines that the transistor Q is in the open trouble and if the output voltage VO is higher than the voltage VB, the boosting circuit control unit 62 determines that the transistor Q is not in the open trouble.
(Problems of the Conventional Determination on Switching Trouble)
The conventional determination on a trouble in the transistor Q by means of the boosting circuit control unit 62 has following problems.
1) When the transistor Q is in the short-circuit trouble, if the power relay RL is turned ON to determine a short-circuit trouble, a rush current flows through a path of vehicle loaded battery B—fuse F—power relay RL—boosting coil L—transistor Q. This rush current is a very large current value even if a noise filter capacitor C2 is provided. For the reason, there is such a problem that a circuit device (fuse F, power relay RL, noise filter capacitor C2, boosting coil L) through which the rush current flows is heated abnormally thereby leading to a trouble. For example, if a non-contact relay is used for the power relay RL, the semiconductor switch can be in the open trouble or short-circuit trouble due to the rush current. Because the power relay RL cannot be turned OFF if the semiconductor switch of the power relay RL is in the short-circuit trouble, the fuse F may melt down due to the rush current. That is, if the non-contact relay is used for the power relay RL, there may occur such double defects that the semiconductor switch of the power relay RL is in the short-circuit trouble and the fuse F melts down due to the rush current. Further, if an electromagnetic relay is used for the power relay RL, there is a fear that the relay contact may be fused due to the rush current. Because the power relay RL cannot be turned OFF if the relay contact of the power relay RL is fused, the fuse F may melt down due to the rush current. That is, if the electromagnetic relay is used for the power relay RL, double defects that the relay contact of the power relay RL is fused and the fuse F melts down due to the rush current may occur. If such double defects occur, which a troubled section exists in the power relay RL or the fuse F cannot be specified, thereby taking a long time for restoration from that trouble.
2) To determine an open trouble of the transistor Q, whether or not the output voltage VO rises over the voltage VB of the vehicle loaded battery is detected by executing the boosting operation by repeating the ON/OFF action of the transistor Q. At this time, to improve the determination accuracy on the open trouble of the transistor Q, it needs to be determined that the transistor Q is not in the open trouble first when the output voltage VO becomes higher than the voltage VB only by the amount corresponding to a margin of a detection error. Thus, the ON/OFF action of the transistor Q needs to be continued until the output voltage VO becomes higher than the voltage VB only by the amount corresponding to the margin of the detection error, so that it takes a long time to obtain a determination result on the open trouble of the transistor Q.

Trouble determining apparatus for DC boosting circuit


In a method and apparatus for identifying the spatial distribution of electrical impedance within an examination subject, a source of electrical current is electrically connected to at least two feed electrodes which impress a feed current from the source in an examination region of a subject. The resulting magnetic field is measured at points outside the examination region, and an equivalent current density distribution is reconstructed within the examination region from the measured values of the magnetic field by an evaluation unit. A compensation conductor is connected to the current source. The current source delivers a compensation current, which flows in a direction opposite to the feed current, through the compensation conductor loop, so that the magnetic field generated by the feed current in the connecting lines is compensated. The evaluation unit identifies the spatial distribution of the impedance from the equivalent current density distribution. The spatial distribution of the impedance can be portrayed on a display.

1. Field of the Invention
The present invention is directed to an apparatus for identifying the spatial distribution of electrical impedance within an examination region of a living subject, as well as to a method for identifying the spatial distribution of electrical impedance within an examination region of a subject.
2. Description of the Prior Art
Various techniques and systems are known for identifying the spatial distribution of electrical impedance within an examination region of a living subject. Systems are known which have the following features.
A source of electrical current is connected via electrical connecting lines to at least two feed electrodes, the feed electrodes being suitable for impressing a feed current from a current source in an examination region of a subject. The impressed current causes a current distribution within the examination region, corresponding to the distribution of electrical impedance and to the position of the electrodes. A magnetic field measuring instrument is then used to acquiring a spatial distribution of characteristic quantities of the magnetic field which arises due to the aforementioned current distribution. This magnetic field is measured at measuring points outside the examination region. The output of the magnetic field measuring instrument is supplied to an evaluation unit, which reconstructs an equivalent distribution of the current density within the examination region based on the spatial distribution of the characteristic quantities. The equivalent current density distribution at the measuring points is that which would be generated by a theoretical magnetic field which best coincides with the measured magnetic field caused by the distribution of the current.
It is known to identify the electrical impedance within a subject non-invasively by means of so-called electrical impedance tomography as described, for example, in the article "Electrical Impedance Tomography and Biomagnetism," Webster, published in Book of Abstracts, 8th International Conference on Biomagnetism, Muenster, Aug. 18-24, 1991, or in the article "Electrical Impedance Tomography; the Construction and Application to Physiological Measurement of Electrical Impedance Images," Brown et al., published in Medical Progress Through Technology 13, pp. 69-75, 1987 Yartinus Nijhoff Publishers, Boston.
In this known techniques, alternating currents having frequencies in the range from 10 through 50 kHz are impressed on the body via electrodes applied to the subject. Tomograms of the conductivity distribution or impedance distribution are calculated in a tomographic reconstruction from the differences in potential which thereby arise between the electrodes.
Published electrical impedance values available in the literature, which were acquired ex vivo or in the course of one-time in vivo examinations, preferably on an animal model, are usually used for producing body-adapted models. The relative magnitude in specific body regions as well as the chronological variation of electrical impedance can be directly consulted for making a medical diagnosis. For example, in vessel or tumor diagnostics as well as in combination with the administration of medications or other therapy measures, deviations of the electrical impedance from standard values, or standard distributions, can be evaluated.
It is proposed in the article "Magnetic Imaging of Conductivity," Ahlfors et al., Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Vol. 14, Paris, France, Oct. 29-Nov. 1, 1992 Part 5, pp. 1717-1718, that a current be impressed on a subject via surface electrodes for identifying the conductivity distribution of the subject, and that the magnetic field generated thereby then be evaluated. It is assumed in this article that only small deviations from a prescribed conductivity distribution occur in the examination region. It is assumed in a further approximation that the magnetic field varies in the same way, as though an additional, equivalent current density distribution were present in the examination region. This additional, equivalent current density distribution is identified by means of a minimum norm estimate from the inverse solution of the measured magnetic field distribution with localization methods which are employed in the field of biomagnetism. The conductivity changes are identified from the equivalent current density distribution, by dividing the equivalent current density distribution by the electrical field of prescribed conductivity distribution, without taking the deviations into consideration.
It has now been shown that the measured values, heretofore thought to arise primarily due to the characteristics of the subject, are in fact dominated by the magnetic field of the entire conductor loop which includes the connecting feed lines, so that a non-uniform current density in the examination region can only be acquired as weak measured values. The magnetic field arising from the connecting lines could be compensated, for example, by subtracting a calculated or measured value corresponding to the contribution of the connecting lines. This would result, however, in a very low sensitivity of the apparatus.

Method and apparatus for non-invasive identification of the endocorporeal spatial distribution of the electrical impedance in a subject


A theoretically optimum motor drive time period or drive pulse width is computed as a function of the number of steps from the present motor shaft position to the desired command position and the present motor shaft rotational speed. A compensation factor is computed as a function of the present motor shaft speed and the torque-speed characteristic of the motor (12) and multiplied by the computed drive time period to produce a present drive time period for energization of the motor (12) for rotation of the motor shaft (14) from the present position to the next step position. After the motor shaft (14) has been rotated to within one step of the command position, sensor means (18') sense displacement of the motor shaft (14) in excess of a predetermined small angular distance from the command position and cause the motor (12) to be energized to rotate the motor shaft (14) toward the command position.

The present invention relates to a servo motor apparatus for a printer, facsimile transceiver or the like. In such an apparatus a theoretically optimum rotational speed of a motor shaft is calculated as a function of the angular distance of the motor shaft from the present step or position to the new desired command step or position. A speed sensor connected to the motor shaft produces pulses corresponding in period or width to the actual motor shaft speed. The theoretical and actual speeds are compared to produce a speed difference signal which is in turn used to calculate a drive pulse time period or pulse width for energizing the motor for movement from the present step to the next step. The theoretical speed is progressively reduced as the motor shaft approaches the command position. The motor may be energized in the forward or reverse directions depending on whether the actual speed is lower or higher than the theoretical speed respectively.
However, several problems have existed heretofore which have caused erroneous operation of this type of servo motor apparatus. One problem is that the drive pulse width is calculated only as a function of the speed difference signal and does not take into account the actual motor shaft speed. The speed difference signal may have the same value over a wide range of motor shaft speeds. Since the motor torque is lower at high speeds than at low speeds, application of a drive pulse having a predetermined pulse width will have a smaller effect at high speed than at low speeds. Thus, the response of the motor to the speed difference progressively decreases as the shaft speed or velocity increases. This causes insufficiently fast response at high shaft speeds which in turn results in overshooting, undershooting and oscillation.
Another problem is that in such a system the motor shaft is positioned in an open loop manner during the last step and thereafter there is no means of preventing rotation of the shaft from the command position. Thus, the final positioning is inaccurate and movement of a load driven by the motor shaft will result in displacement of the motor shaft from the desired position.


The invention provides polyurethane elastomers (PU elastomers), a process for their production using special catalyst mixtures and their use in particular for the manufacture of shoe soles.

The invention is directed to polyurethane elastomers (PU elastomers), a process for their production with special catalyst mixtures and uses thereof.
PU elastomers have long been known and have already been customized for a wide variety of applications, see for example U.S. Pat. No. 5,952,053. In order to control their polymerization rates, a large number of diverse metal catalysts have been investigated and used. In addition to the widespread use of organotin compounds, it is also known to use organic compounds or organic salts of various other elements, such as lithium, titanium and bismuth.
The use of lithium salts of organic acids has also been described. Mixtures of a lithium carboxylate, namely lithium neodecanoate, lithium octanoate, lithium stearate or lithium naphthenate, and a zinc carboxylate are described in U.S. Pat. No. 4,256,847 as an effective catalyst combination for rigid foam applications. Lithium is known to be highly active. Other publications list lithium as the sole metal catalyst for the catalysis of PU reactions. In U.S. Pat. No. 4,107,069, lithium carboxylates are used as stable gel catalysts for rigid PU foams. U.S. Pat. No. 3,108,975 discloses their use as catalysts for rigid and flexible, as well as, cellular and non-cellular polyurethanes. The use of lithium carboxylates as a trimerization catalyst is likewise known, in fact in U.S. Pat. No. 3,634,345, moisture-insensitive, readily soluble aromatic carboxylates are used for PU resin production. in U.S. Pat. No. 3,940,517 aliphatic lithium carboxylates are used for PU foams and in U.S. Pat. Nos. 6,127,308 and 5,955,609, the controllability of the trimerization reaction is used for PU foams and prepolymer synthesis. The same procedure is used in the production of rigid foams in DE-A 59 101 001. Finally, in U.S. Pat. No. 2,894,919, lithium carboxylates, namely lithium stearate and lithium caprylate, are used as catalysts in order to produce exclusively elastic, flexible PU foams.
Organic titanium compounds have been used since the 1960""s as catalysts for the synthesis of polyurethanes, such as those listed in U.S. Pat. No. 5,902,835. Known organic titanium compounds include, titanium carboxylates, as disclosed in U.S. Pat. No. 5,162,382, alkyl titanates, as disclosed in Saunders, J. H.; Frisch, K. C. Polyurethanesxe2x80x94Chemistry and Technology (1962) London Part I p. 168, JP 2 001/026 629, JP 5 097 952 and titanium diketonates and titanium xcex2-keto esters, as disclosed in U.S. Pat. No. 5,902,835, DE-A 19 626 007, WO 98/15585, Chemical Abstract, Vol. 108:56652. Organic titanium compounds are commonly used as expansion and gel catalysts. Their range of applications extends from water-expanded PU foams and mechanically foamed, thermally curing PU foams to PU surface coatings to RIM systems for flexible PU foams.
Organic bismuth compounds are also known to be used as catalysts, see for example, Luo, S.-G.; Tan, H.-M.; Zhang, J.-G.; Wu, Y.-J.;
Pei, F.-K.; Meng, X.-H. J. Appl. Polym. Sci. (1997) 65(6), p. 1217-1225. Of the group of organic bismuth compounds, carboxylates are predominantly used, as disclosed in CA-A 2 049 695, DE-A 19 618 825, U.S. Pat. No. 5,792,811, and WO 2000/47642. In addition, bismuth organothiolates are used as latent catalysts, see for example, WO 95/29007 and U.S. Pat. Nos. 5,910,373, and 6,190,524. The use of bismuth compounds together with organic zinc or tin compounds is also known, see for example WO 96/20967, U.S. Pat. Nos. 5,910,373, 6,001,900, 5,859,165, 6,124,380 and 6,190,524, WO 98/14492 and WO 2000/46306. The field of application for the use of bismuth catalysts mentioned above is mainly in the area of surface coating.
In addition to the combinations of metal catalysts already mentioned, such as e.g. tin and zinc compounds, a number of catalyst combinations comprising organic compounds, of the elements, lithium, titanium or bismuth can also be found in the literature. U.S. Pat. Nos. 5,952,053, 5,952,053 and WO 2000/46306 list combinations of lithium and bismuth compounds and U.S. Pat. No. 5,902,835 discloses that organic titanium compounds can be combined with bismuth compounds, however these metal catalyst combinations display no special effects.
Shoe soles, among other things, are an important application for PU elastomers. The catalyst systems used in their production must provide for good processability of the soles. Specifically, this includes short demolding times and high demolding hardness values, as well as, long cream times, to ensure that every part of the mold is filled. The catalysts must also promote good end properties, such as high final hardness values and low puncture expansion values under repeated flexural stress. Commercial organotin catalysts do not satisfy this list of requirements.
An object of the present invention is to provide PU elastomers having high final hardness values and low puncture expansion values under repeated flexural stress, as well as a process, in which short demolding times, high demolding hardness values and long cream times are possible.
Surprisingly this object can be achieved with special catalyst combinations containing lithium and titanium compounds or organic lithium, titanium and bismuth compounds. In the case of a three-component mixture, the concentration of catalyst used can also be reduced, in comparison to the two-component mixture, with an otherwise identical effect, giving rise, in addition, to toxicological and economic advantages.
The invention provides polyurethane elastomers produced by reacting
a) organic diisocyanates and/or polyisocyanates with
b) at least one polyether polyol having a number-average molecular weight of 800 g/mol to 25,000 g/mol, preferably 800 to 14,000 g/mol, more preferably 2,000 to 9,000 g/mol and having an average functionality of 1.6 to 2.4, preferably 1.8 to 2.4,
c) optionally at least a second polyether polyol differing from b) and having a number-average molecular weight of 800 g/mol to 25,000 g/mol, preferably 800 to 14,000 g/mol, more preferably 2,000 to 9,000 g/mol and having average functionalities of 2.4 to 8, more preferably 2.5 to 3.5,
d) optionally polymer polyols containing 1 to 50 wt. %, preferably 1 to 45 wt. % filler, relative to polymer polyol, and having hydroxyl values of 10 to 149 and average functionalities of 1.8 to 8, preferably 1.8 to 3.5,
e) optionally low-molecular chain extenders having average functionalities of 1.8 to 2.1, preferably 2, and having molecular weights of 750 g/mol and lower, preferably 18 g/mol to 400 g/mol, more preferably 60 g/mol to 300 g/mol, and/or crosslinking agents having average functionalities of 3 to 4, preferably 3, and having molecular weights of up to 750 g/mol, preferably 18 g/mol to 400 g/mol, particularly preferably 60 g/mol to 300 g/mol, in the presence of
f) amine catalysts and a catalyst mixture containing
i) at least one organic titanium and/or zirconium compound,
ii) and at least one organic lithium carboxylate,
iii) optionally additionally at least one organic bismuth carboxylate,
g) optionally blowing agents, and
h) optionally additives,
wherein the ratio of the amount of substance nTi of titanium ions and/or nZr of zirconium ions in component i) to the amount of substance nLi of lithium ions in component ii) is 0.2 to 4, preferably 0.43 to 1.5 and if component iii) is used the ratio of the amount of substance nBi of bismuth ions in component iii) to the sum of the amounts of substance nTi and/or nZr and nLi is 0.0001 to 0.53, preferably 0.0001 to 0.24, more preferably 0.0001 to 0.15.
The PU elastomers are preferably produced by the prepolymer process, whereby in the first step a polyaddition adduct, having isocyanate groups, is produced from at least a portion of the polyether polyol b) or a mixture thereof, with polyol component c) and at least one diisocyanate or polyisocyanate a). In the second step solid PU elastomers can be produced from prepolymers having such isocyanate groups, by the reaction with low-molecular weight chain extenders and/or crosslinking agents d) and/or the remaining portion of the polyol components b) and optionally c). If water or another blowing agent, or mixtures thereof, are additionally used in the second step, microcellular PU elastomers can be produced.
Aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, such as those described by W. Siefken in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136, are suitable as starting component a) for the process according to the present invention, for example those having the formula:
Q(NCO)n
in which n denotes 2-4, preferably 2, and Q denotes an aliphatic hydrocarbon radical with 2 to 18, preferably 6 to 10 C atoms, a cycloaliphatic hydrocarbon radical with 4 to 15, preferably 5 to 10 C atoms, an aromatic hydrocarbon radical with 6 to 15, preferably 6 to 13 C atoms, or an araliphatic hydrocarbon radical with 8 to 15, preferably 8 to 13 C atoms. Suitable examples include ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 1,12-dodecane. diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate and any mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane, 2,4- and 2,6- hexahydro-toluene diisocyanate and any mixtures of these isomers, hexahydro-1,3-and -1,4-phenylene diisocyanate, perhydro-2,4xe2x80x2- and 4,4xe2x80x2-diphenylmethane diisocyanate, 1,3- and 1,4-phenylene diisocyanate, 1,4-durene diisocyanate (DDI), 4,4xe2x80x2-stilbene diisocyanate, 3,3xe2x80x2-dimethyl4,4xe2x80x2-biphenylene diisocyanate (TODI), 2,4- and 2,6-toluene diisocyanate (TDI) and any mixtures of these isomers, diphenylmethane-2,4xe2x80x2- and/or -4,4xe2x80x2-diisocyanate (MDI), or naphthylene-1,5-diisocyanate (NDI).
Other examples include, triphenylmethane-4,4xe2x80x2,4xe2x80x3-triisocyanate, polyphenyl polymethylene polyisocyanates, such as those obtained by aniline-formaldehyde condensation and subsequent phosgenation and those described in GB-A 874 430 and GB-A 848 671, m- and p-isocyanatophenyl sulfonyl isocyanates according to U.S. Pat. No. 3,454,606, perchlorinated aryl polyisocyanates, such as those described in U.S. Pat. No. 3,277,138, polyisocyanates having carbodiimide groups, such as those described in U.S. Pat. No. 3,152,162 and in DE-A 25 04 400, DE-A 25 37 685 and DE-A 25 52 350, norbornane diisocyanates according to U.S. Pat. No. 3,492,301, polyisocyanates having allophanate groups, such as those described in GB-A 994 890, BE-A 761 626 and NL-A 7 102 524, polyisocyanates having isocyanurate groups, such as those described in U.S. Pat. No. 3,001,9731, in DE-A 10 22 789, DE-A 12 22 067 and DE-A 1 027 394, as well as in DE-A 1 929 034 and DE-A 2 004 048, polyisocyanates having urethane groups, such as those described in BE-A 752 261 or in U.S. Pat. No. 3,394,164 and DE-A 3 644 457, polyisocyanates having acylated urea groups according to DE-A 1 230 778, polyisocyanates having biuret groups, such as those described in U.S. Pat. Nos. 3,124,605, 3,201,372 and U.S. Pat. No. 3,124,605 and in GB-A 889 050, polyisocyanates produced by telomerization reactions, such as those described in U.S. Pat. No. 3,654,106, polyisocyanates having ester groups, such as those cited in GB-A 965 474 and GB-A 1 072 956, in U.S. Pat. No. 3,567,763 and in DE-A 12 31 688, reaction products of the above-mentioned isocyanates with acetals according to DE-A 1 072 385 and polyisocyanates containing polymeric fatty acid esters according to U.S. Pat. No. 3,455,883.
The distillation residues having isocyanate groups that are obtained during industrial isocyanate production, optionally dissolved in one or more of the aforementioned polyisocyanates, can also be used. It is also possible to use any mixture of the aforementioned polyisocyanates. Polyisocyanates that are readily accessible in industry are preferably used, for example 2,4- and 2,6-toluene diisocyanate and any mixtures of these isomers (xe2x80x9cTDIxe2x80x9d), 4,4xe2x80x2-diphenylmethane diisocyanate, 2,4xe2x80x2-diphenylmethane diisocyanate, 2,2xe2x80x2-diphenylmethane diisocyanate and polyphenyl polymethylene polyisocyanates, such as are produced by aniline-formaldehyde condensation and subsequent phosgenation (xe2x80x9ccrude MDIxe2x80x9d), and polyisocyanates having carbodiimide groups, uretonimine groups, urethane groups, allophanate groups, isocyanurate groups, urea groups or biuret groups (xe2x80x9cmodified polyisocyanatesxe2x80x9d), in particular modified polyisocyanates that are derived from 2,4- and/or 2,6-toluene diisocyanate or from 4,4xe2x80x2- and/or 2,4xe2x80x2-diphenylmethane diisocyanate. Naphthylene-1,5-diisocyanate and mixtures of the cited polyisocyanates are also suitable.
Prepolymers having isocyanate groups that are produced by reacting at least a portion of the polyol component b) and/or c) and/or chain extenders and/or crosslinking agents e) with at least one aromatic diisocyanate from the group TDI, MDI, TODI, DIBDI, NDI, DDI, preferably with 4,4xe2x80x2-MDI and/or 2,4-TDI and/or 1,5-NDI, to form a polyaddition product, having urethane groups and isocyanate groups, and having an NCO content of 10 to 27 wt. %, preferably 12 to 25 wt. %, are preferably used.
As stated above, mixtures of components b), c) and e) can be used to produce the isocyanate group-containing prepolymers. Preferably, the prepolymers containing isocyanate groups are produced without chain extenders or crosslinking agents e).
Prepolymers having isocyanate groups can be produced in the presence of catalysts. It is also possible to produce the prepolymers in the absence of catalysts. However, the catalyst is incorporated into the reaction mixture for production of the PU elastomers.
Suitable polyether polyols b) or c) useful for production of the elastomers, according to the present invention, can be produced by known methods, for example by polyinsertion via DMC catalysis of alkylene oxides, by anionic polymerization of alkylene oxides in the presence of alkali hydroxides or alkali alcoholates as catalysts and with the addition of at least one initiator molecule containing 2 to 6, preferably 2 to 4 reactive hydrogen atoms in bonded form, or by cationic polymerization of alkylene oxides in the presence of Lewis acids such as antimony pentachloride or boron fluoride etherate. Suitable alkylene oxides contain 2 to 4 carbon atoms in the alkylene radical. Examples include tetrahydrofuran, 1,2-propylene oxide, 1,2- or 2,3-butylene oxide; ethylene oxide and/or 1,2-propylene oxide are preferably used. The alkylene oxides can be used individually, in succession or as a mixture. Mixtures of 1,2-propylene oxide and ethylene oxide are preferably used, whereby the ethylene oxide is used in quantities of 10 to 50% as an ethylene oxide terminal block (xe2x80x9cEO capxe2x80x9d) so that the resulting polyols display over 70% primary OH terminal groups. Examples of initiator molecules include water or dihydric and trihydric alcohols, such as ethylene glycol, 1,2-propanediol and 1,3-propanediol, diethylene glycol, dipropylene glycol, ethane-1,4-diol, glycerol, trimethylol propane, etc. Suitable polyether polyols, preferably polyoxypropylene polyoxyethylene polyols, have average functionalities of 1.6 to 2.4, preferably 1.8 to 2.4, and number-average molecular weights of 800 g/mol to 25,000 g/mol, preferably 800 to 14,000 g/mol, particularly preferably 2,000 to 9,000 g/mol.
Difunctional or trifunctional polyether polyols having a number-average molecular weight of 800 to 25,000, preferably 800 to 14,000 g/mol, more preferably 2,000 to 9,000 g/mol, are used as components b) or c) in the production of the elastomers according to the present invention.
Also suitable as polymer polyols d), in addition to the above-mentioned polyether polyols, are polymer-modified polyether polyols, preferably graft polyether polyols, in particular those based on styrene and/or acrylonitrile that are produced by in-situ polymerization of acrylonitrile, styrene or preferably mixtures of styrene and acrylonitrile, in a ratio by weight of 90:10 to 10:90, preferably 70:30 to 30:70, and polyether polyol dispersions which contain as disperse phase, in quantities of 1 to 50 wt. %, preferably 1 to 45 wt. %, relative to polymer polyol, inorganic fillers, polyureas (PHD), polyhydrazides, polyurethanes containing tert.-amino groups in bonded form and/or melamine, for example.
Low-molecular difunctional chain extenders, trifunctional or tetrafunctional crosslinking agents or mixtures of chain extenders and crosslinking agents can additionally be used as component e) to produce the PU elastomers according to the present invention.
Such chain extenders and crosslinking agents e) are used to modify the mechanical properties, in particular the hardness of the PU elastomers. Suitable chain extenders include alkane diols, dialkylene glycols and polyalkylene polyols, and crosslinking agents, such as trihydric or tetrahydric alcohols and oligomeric polyalkylene polyols with a functionality of 3 to 4 and molecular weights less than 750 g/mol, preferably from 18 to 400 g/mol, more preferably from 60 to 300 g/mol. Alkane diols having 2 to 12, preferably 2, 4 or 6 carbon atoms, such as ethanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol and in particular 1,4-butanediol, and dialkylene glycols having 4 to 8 carbon atoms, such as diethylene glycol and dipropylene glycol as well as polyoxyalkylene glycols, are preferably used as chain extenders. Also suitable are branched-chain and/or unsaturated alkane diols with no more than 12 carbon atoms, such as 1,2-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butene-1,4-diol and 2-butyne-1,4-diol, diesters of terephthalic acid with glycols having 2 to 4 carbon atoms, such as terephthalic acid-bis-ethylene glycol or terephthalic acid-bis-1,4-butanediol, hydroxyalkylene ethers of hydroquinone or resorcinol, e.g. 1,4-di(xcex2-hydroxyethyl) hydroquinone or 1,3-(xcex2-hydroxyethyl) resorcinol, alkanolamines with 2 to 12 carbon atoms such as ethanolamine, 2-aminopropanol and 3-amino-2,2-dimethyl propanol, N-alkyl dialkanolamines, such as N-methyl and N-ethyl diethanolamine, (cyclo)aliphatic diamines with 2 to 15 carbon atoms, such as 1,2-ethylene diamine, 1,3-propylene diamine, 1,4-butylene diamine and 1,6-hexa-methylene diamine, isophorone diamine, 1,4-cyclohexamethylene diamine and 4,4xe2x80x2-diaminodicyclohexyl methane, N-alkyl-substituted, N,Nxe2x80x2-dialkyl-substituted and aromatic diamines, which can also be substituted at the aromatic radical by alkyl groups, having 1 to 20, preferably 1 to 4 carbon atoms in the N-alkyl radical, such as N,Nxe2x80x2-diethyl, N,Nxe2x80x2-di-sec.-pentyl, N,Nxe2x80x2-di-sec.-hexyl, N,Nxe2x80x2-di-sec.-decyl and N,Nxe2x80x2-dicyclohexyl (p- or m-) phenylene diamine, N,Nxe2x80x2-dimethyl, N,Nxe2x80x2-diethyl, N,Nxe2x80x2-diisopropyl, N,Nxe2x80x2-di-sec.-butyl, N,Nxe2x80x2-dicyclohexyl, -4,4xe2x80x2-diaminodiphenylmethane, N,Nxe2x80x2-di-sec.-butyl benzidine, methylene bis(4-amino-3-methyl benzoate), 2,4-chloro-4,4xe2x80x2-diaminodiphenylmethane, 2,4- and 2,6-toluene diamine.
The compounds in component e) can be used in the form of mixtures or individually. Mixtures of chain extenders and crosslinking agents can also be used.
To adjust the hardness of the PU elastomers, components b), c), d) and e) can be varied in relatively broad proportions. For example, the hardness increases with the rising content of component e) in the reaction mixture.
The amounts of components b), c), d) and e) that are used to obtain the desired hardness in the PU elastomer can easily be determined by experiment. For example, 1 to 50 parts by weight, preferably 2.5 to 20 parts by weight of the chain extender and/or crosslinking agent e), relative to 100 parts by weight of the higher-molecular compounds b), c) and d) can be used.
Amine catalysts that are familiar to a person skilled in the art can be used as component f), for example tertiary amines such as triethylamine, tributylamine, N-methyl morpholine, N-ethyl morpholine, N,N,Nxe2x80x2,Nxe2x80x2-tetramethyl ethylene diamine, pentamethyl diethylene triamine and higher homologues, according to DE-A 26 24 527 and DE-A 26 24 528, 1,4-diazabicyclo-[2,2 ,2]-octane, N-methyl-Nxe2x80x2-dimethylaminoethyl piperazine, bis(dimethylaminoalkyl) piperazine, N,N-dimethyl benzylamine, N,N-dimethyl cyclohexylamine, N,N-diethyl benzylamine, bis(N,N-diethylaminoethyl) adipate, N,N,Nxe2x80x2,Nxe2x80x2-tetramethyl-1,3-butane diamine, N,N-dimethyl-xcex2-phenyl ethylamine, bis(dimethylaminopropyl) urea, bis(dimethylaminopropyl) amine, 1,2-dimethyl imidazole, 2-methyl imidazole, monocyclic and bicyclic amidines, bis(dialkylamino) alkyl ethers, such as e.g. bis(dimethylaminoethyl) ethers, and tertiary amines having amide groups (preferably formamide groups) according to DE-A 25 23 633 and DE-A 27 32 292. Other examples of catalysts include known Mannich bases consisting of secondary amines, such as dimethylamine, and aldehydes, preferably formaldehyde, or ketones such as acetone, methyl ethyl ketone or cyclohexanone and phenols, such as phenol, nonyl phenol or bisphenol. Catalysts in the form of tertiary amines having hydrogen atoms that are active with respect to isocyanate groups are e.g. triethanolamine, triisopropanolamine, N-methyidiethanolamine, N-ethyl diethanolamine, N,N-dimethyl ethanolamine, reaction products thereof with alkylene oxides such as propylene oxide and/or ethylene oxide and secondary-tertiary amines according to DE-A 27 32 292. Silamines with carbon-silicon bonds, such as are described in U.S. Pat. No. 3,620,984, can also be used as catalysts, for example, 2,2,4-trimethyl-2-silamorpholine and 1,3-diethyl aminomethyl tetramethyl disiloxane. Other examples include nitrogen-containing bases such as tetraalkyl ammonium hydroxides, and also hexahydrotriazines. The reaction between NCO groups and Zerewitinoff-active hydrogen atoms is also accelerated by lactams and azalactams.
At least one organic carboxylate of lithium ii) with at least one organic compound of titanium and/or zirconium i) is preferably used as catalyst. If necessary the catalyst combination can be extended with at least one bismuth compound iii) as the third component. The catalysts can be added to the polyol formulation either as a prepared mixture or separately in the corresponding ratio. Separate addition is preferred.
Saturated or unsaturated, aliphatic or alicyclic and aromatic carboxylates of lithium that are familiar to the person skilled in the art can preferably be used as component ii). They correspond to the following general formulae:
[Li(OOCR)]
[Li2((OOC)2R)]
wherein R is a hydrocarbon radical with 1 to 25 carbon atoms. Preferred catalysts include lithium(l) versatate, tallate, oxalate, adipate and stearate. More preferred catalysts are lithium(l) naphthenate, decanoate, butyrate, isobutyrate, nonate, benzoate and caprioate. Lithium(l) neodecanoate, 2-ethyl hexanoate and octanoate are also preferred.
Component ii) can also a solution of a lithium hydroxide or carbonate or a solution of a mixture of these salts in one or more of the carboxylic acids described above.
Organic compounds of titanium and/or zirconium that are familiar to a person skilled in the art can be used as component i). They preferably correspond to the following general formulae:
[M(L1)(L2)(L3)(L4)]n
[M(L1)(L2)(L3)]n
[M(L1)(L2)]n
[M(L1)]n
wherein M denotes titanium and zirconium, n can assume values from 1 to 20 and L1, L2, L3 and L4 are the same or different and can be ligands of the following groups co-ordinated via O, S or N atoms:
(1) Alcoholates, phenolates, glycolates, thiolates, carboxylates or amino alcoholates containing 1 to 20 carbon atoms and optionally one or more functional groups (e.g. hydroxyl, amino, carbonylato, etc.) or having bonds containing oxygen, sulfur or nitrogen (such as, in ethers, thioethers, amines or carbonyls),
(2) Various fluorine-free, sterically unhindered chelating ligands from the group of 1-diketones, such as benzoyl acetone, dibenzoyl methane, ethyl benzoyl acetate, methyl acetoacetate, ethyl acetoacetate and 2,4-pentane dione (also known as acetylacetone) and other chelating ligands, such as N,N-dimethyl ethanolamine, triethanolamine, salicylaldehyde, salicylamide, phenyl salicylate, cyclopentanone-2-carboxylic acid, bisacetyl acetylacetone, thioacetylacetone, N,Nxe2x80x2-bis(salicylidene) ethylene diamine, glycolic acid, ethylene glycol etc.
Preferred components i) include titanium(IV) isopropoxide, titanium(IV)-n-butoxide, titanium(IV)-2-ethyl hexoxide, titanium(IV)-n-pentoxide, titanium(IV) (triethanolaminato) isopropoxide, titanium(IV) (triethanolaminato)-n-butoxide, isopropyl triisostearyl titanate, bis(8-quinolinolato) titanium(IV) dibutoxide, bis(ethyl acetoacetato) titanium(IV) diisobutoxide, titanium(IV) bis(ethyl acetoacetato) diisopropoxide, zirconium(IV) isopropoxide, zirconium(IV)-n-butoxide, zirconium(IV)-2-ethyl hexoxide, zirconium(IV)-n-pentoxide, zirconium(IV) (triethanolaminato) isopropoxide, zirconium(IV) (triethanolaminato)-n-butoxide, isopropyl triisostearyl zirconate, bis(8-quinolinolato) zirconium(IV) dibutoxide and bis(ethyl acetoacetato) zirconium(IV) diisobutoxide.
More preferred are titanium compounds with ligands such as those listed in paragraph (2) above. Of these titanium compounds, titanium(IV) diisopropoxide-bis(2,4-pentane dionate), titanium(IV) triisopropoxide (2,4-pentane dionate), ethoxy-bis(pentane-2,4-dionato-0,0xe2x80x2)(propan-2-olato) titanium, titanium(IV) oxide acetylacetonate, bis(diacetylacetonato) titanium(IV) butoxide isopropoxide and bis(diacetylacetonato) titanium(IV) ethoxide isopropoxide are preferably used.
Many of the catalysts listed under i) can form agglomerates and/or higher-molecular condensation products having two or more metal sites, which are connected with one another by one or more bridging ligands. For that reason n can vary from 1 to approximately 20. Compounds having n between 1 and 10 are preferred.
Component iii) contains saturated or unsaturated, aliphatic or alicyclic and aromatic bismuth carboxylates and preferably correspond to the following general formulae:
[Bi(OOCR)3]
[Bi2((OOC)2R)3]
wherein R is a hydrocarbon radical having 1 to 25 carbon atoms.
Preferred carboxylates include bismuth(III) versatate, tallate, stearate, adipate, oxalate. Bismuth(III) naphthenate, decanoate, butyrate, isobutyrate, nonate, caprioate are also preferred. Bismuth(III) neodecanoate, -2-ethyl hexanoate and octanoate are more preferred.
Components i), ii) and/or iii) are preferably used as liquid preparations with one or more solvents. Saturated or unsaturated, aliphatic or alicyclic and aromatic carboxylic acids having the general formulae:
RCOOH
HOOCxe2x80x94Rxe2x80x94COOH
can be used as solvent, wherein R is a hydrocarbon radical having 1 to 25 carbon atoms. Neodecanoic acid, 2-ethyl hexanoic acid and naphthenic acid, for example, are preferred.
In place of the aforementioned carboxylic acids, the following solvents can also be used:
(1) Aliphatic and aromatic liquids, such as Stoddard solvents, naphtha, white spirit, petroleum spirits, xylene, hexane, heptane, toluene and paraffinic mineral oil,
(2) Esters, such as ethyl acetate and isopropyl acetate,
(3) Alcohols, such as ethanol, n-propanol, isopropanol, n-butanol, 2-(2-butoxyethoxy) ethanol, 2-(2-ethoxyethoxy) ethanol, diethylene glycol, triethylene glycol, diethylene glycol monoethyl ether, ethylene glycol,
(4) Ketones, such as methyl ethyl ketone, acetone and
(5) Ethers, such as diethylene glycol butyl ether
(6) and water.
The catalyst combinations of components i) and ii) or i), ii) and iii) are generally used in a quantity of between approximately 0.001 and 10 wt. %, preferably 0.01 to 0.5 wt. %, relative to the total amount of compounds from b) to h).
The catalyst combinations of components i) and ii) are mixed in a ratio of the amount of substance nTi of titanium ions and/or nZr of zirconium ions in component i) to the amount of substance nLi of lithium ions in component ii) such that values of 0.2 to 4, preferably 0.43 to 1.5 are established. If component iii) is additionally used, component iii) is used in an amount of substance nBi of bismuth ions in component iii) such that the ratio of the amount of substance nBi of bismuth ions in component i) to the sum of nTi and/or nZr and nLi is 0.0001 to 0.53, preferably 0.0001 to 0.24, more preferably 0.0001 to 0. 15.
In the absence of moisture and physically or chemically acting blowing agents, compact PU elastomers, for example, PU shoe outer soles can be produced.
In the production of microcellular PU elastomers, water is preferably used as blowing agent g), which reacts in situ with the organic diisocyanates and/or polyisocyanates or with the prepolymers a) having isocyanate groups to form carbon dioxide and amino groups, which in turn undergo further reaction with other isocyanate groups to form urea groups, thereby acting as chain extenders.
When water is added to the polyurethane formulation to establish the desired density, it is used in quantities from 0.001 t o 3.0 wt. %, preferably 0.01 to 2.0 wt. % and in particular 0.05 to 0.7 wt. %, relative to the weight of components a), b) and optionally c), d) and e).
As blowing agent g), gases or highly volatile inorganic or organic substances which evaporate under the influence of the exothermic polyaddition reaction and preferably have a boiling point under normal pressure ranging from xe2x88x9240 to 120xc2x0 C., preferably xe2x88x9230 to 90xc2x0 C., can also be used as physical blowing agents in place of water or preferably in combination with water. Examples include acetone, ethyl acetate, halogen-substituted alkanes or perhalogenated alkanes, such as (R134a, R141b, R365mfc, R245fa), also butane, pentane, cyclopentane, hexane, cyclohexane, heptane or diethyl ether as organic blowing agents, and air, CO2 or N2O as inorganic blowing agents.
An expansion effect can also be achieved by adding compounds that decompose at temperatures above room temperature with release of gases such as nitrogen and/or carbon dioxide, such as azo compounds, for example, azodicarbonamide or azoisobutyric acid nitrile, or salts such as ammonium bicarbonate, ammonium carbamate or ammonium salts of organic carboxylic acids, e.g. monoammonium salts of malonic acid, boric acid, formic acid or acetic acid. Further examples of blowing agents and details of the use of blowing agents are described in R. Vieweg, A. Hxc3x6chtlen (Eds.): xe2x80x9cKunststoff-Handbuchxe2x80x9d, Volume VII, Carl-Hanser-Verlag, Munich, 3rd Edition, 1993, p. 115 to 118, 710 to 715.
The amount of solid blowing agents, low-boiling liquids or gases to be used, which in each case can be used alone or in the form of mixtures, such as liquid or gas mixtures or as gas-liquid mixtures, depending on the desired density and on the amount of water used. The desired amounts can easily be determined by experiment. Satisfactory results are delivered by amounts of solids of 0.5 to 35 wt. %, preferably 2 to 15 wt. %, amounts of liquids of 0.5 to 30 wt. %, preferably 0.8 to 18 wt. % and/or amounts of gases of 0.01 to 80 wt. %, preferably 10 to 50 wt. %, relative in each case to the weight of components a), b), c) d) and e). The introduction of gas, e.g. air, carbon dioxide, nitrogen and/or helium, can be achieved both through the higher-molecular polyhydroxyl compounds b), c) and d), through the low-molecular chain extender and/or crosslinking agent e) and through the polyisocyanates a) or through a) and b) and optionally c), d) and e).
Additives h) can optionally be added to the reaction mixture for production of compact or cellular PU elastomers. Examples that can be cited include surface-active additives, such as emulsifiers, foam stabilizers, cell regulators, flame retardants, nucleating agents, oxidation retarders, stabilizers, lubricants and mold release agents, dyes, dispersing agents and pigments. Examples of emulsifiers include the sodium salts of castor oil sulfonates or salts of fatty acids with amines such as oleic acid diethylamine or stearic acid diethanolamine. Alkali or ammonium salts of sulfonic acids such as dodecyl benzene sulfonic acid or dinaphthyl methane disulfonic acid for example or of fatty acids such as ricinoleic acid or of polymeric fatty acids can also additionally be used as surface-active additives. Examples of foam stabilizers include polyether siloxanes, preferably water-soluble examples. These compounds are generally structured so that a copolymer of ethylene oxide and propylene oxide is bonded with a polydimethyl siloxane radical. Such foam stabilizers are described in U.S. Pat. Nos. 2,834,748, 2 ,917, 480 and 3,629,308. Of particular interest are polysiloxane-polyoxyalkylene copolymers according to DE-A 25 58 523 that are multiply branched by means of allophanate groups. Also suitable are other organopolysiloxanes, oxyethylated alkyl phenols, oxyethylated fatty alcohols, paraffin oils, castor oil or ricinoleic acid esters, sulfated castor oil, peanut oil and cell regulators such as paraffins, fatty alcohols and polydimethyl siloxanes. Oligomeric polyacrylates with polyoxyalkylene and fluoroalkane radicals as side groups are also suitable for improving the emulsifying effect, dispersion of the filler, cell structure and/or stabilization. The surface-active substances are conventionally used in quantities of 0.01 to 5 parts by weight, relative to 100 parts by weight of the higher-molecular polyhydroxyl compounds b) and c). Reaction retarders, also pigments or dyes and flame retardants known per se, also stabilizers against the effects of aging and weathering, plasticizers and substances having fungistatic and bacteriostatic activity can also be added.
Other examples of surface-active additives and foam stabilizers as well as cell regulators, reaction retarders, stabilizers, flame-retardant substances, plasticizers, dyes and fillers and substances having fungistatic and bacteriostatic activity that can optionally additionally be used, as well as details of the mode of use and action of these additives are described in R. Vieweg, A. Hxc3x6chtlen (Eds.): xe2x80x9cKunststoff-Handbuchxe2x80x9d, Volume VII, Carl-Hanser-Verlag, Munich, 3rd Edition, 1993, p. 118 to 124.
To produce the PU elastomers according to the present invention the components are reacted in quantities so that the equivalent ratio of NCO groups in isocyanates a) to the sum of the isocyanate group-reactive hydrogens in components b), c), d) and e) and of any chemically acting blowing agents g) that may be used is 0.8:1 to 1.2:1, preferably 0.95:1 to 1.15:1 and more preferably 1.00:1 to 1.05:1.
The PU elastomers according to the present invention can be produced by the processes described in the literature, such as the one-shot or prepolymer process, with the aid of mixing devices that are known to a person skilled in the art. Preferably, the PU elastomers are produced by the prepolymer process.
In one embodiment of the production of the PU elastomers according to the invention the starting components are homogeneously mixed in the absence of blowing agents g), at a temperature of 20 to 80xc2x0 C., preferably 25 to 60xc2x0 C., the reaction mixture introduced into an open, optionally temperature-controlled mold and cured. In another variant of the production of the PU elastomers according to the invention the structural components are mixed in the presence of blowing agents g), preferably water, and introduced into the optionally temperature-controlled mold. After it has been filled the mold is closed and the reaction mixture is allowed to foam with packing. The degree of packing (ratio of molding density to free foam density) used is 1.05 to 8, preferably 1.1 to 6 and in particular 1.2 to 4, to form moldings. As soon as the moldings have sufficient strength they are demolded. The demolding times are dependent inter alia on the temperature and geometry of the mold and on the reactivity of the reaction mixture and are conventionally 1.5 to 15 minutes.
The PU elastomers according to the present invention have densities ranging from 180 to 1100 kg/m3, depending inter alia on the content and type of filler. They are used for example in molded soles or in one-component direct soling systems with densities of 400 to 650 kg/m3, in boot legs with densities of 500 to 700 kg/m3, in tightly compressed or compact outer soles of two-layer soles or direct soling systems with densities of 800 to 1100 kg/m3, in intermediate soles of two-layer soles or direct soling systems with densities of 400 to 500 kg/m3 and in insoles with densities of 180 to 400 kg/m3.
The PU elastomers according to the invention are especially valuable raw materials for shoe soles having a single or multi-layered construction.

Polyurethane elastomers, process for their production and use thereof


A method of treating the intraluminal disease in a coronary artery by injecting therapeutic agents perivascularly into the myocardium near the site of disease.

Local drug delivery provides many advantages. Approaches for local controlled release of agents at a depth within a tissue such as the heart, pancreas, esophagus, stomach, colon, large intestine, or other tissue structure to be accessed via a controllable catheter will deliver drugs to the sites where they are most needed, reduce the amount of drug required, increase the therapeutic index, and control the time course of agent delivery. These, in turn, improve the viability of the drugs, lower the amount (and cost) of agents, reduce systemic effects, reduce the chance of drug-drug interactions, lower the risk to patients, and allow the physician to more precisely control the effects induced. Such local delivery may mimic endogenous modes of release, and address the issues of agent toxicity and short half lives.
Local drug delivery to the heart is known. In U.S. Pat. No. 5,551,427, issued to Altman, implantable substrates for local drug delivery at a depth within the heart are described. The patent shows an implantable helically coiled injection needle which can be screwed into the heart wall and connected to an implanted drug reservoir outside the heart. This system allows injection of drugs directly into the wall of the heart acutely by injection from the proximal end, or on an ongoing basis by a proximally located implantable subcutaneous port reservoir, or pumping mechanism. The patent also describes implantable structures coated with coating which releases bioactive agents into the myocardium. This drug delivery may be performed by a number of techniques, among them infusion through a fluid pathway, and delivery from controlled release matrices at a depth within the heart. Controlled release matrices are drug polymer composites in which a pharmacological agent is dispersed throughout a pharmacologically inert polymer substrate. Sustained drug release takes place via particle dissolution and slowed diffusion through the pores of the base polymer. Pending applications Ser. No. 08/816,850 by Altman and Altman, and Ser. No. 09/057,060 by Altman describes some additional techniques for delivering pharmacological agents locally to the heart. Implantable drug delivery systems, such as controlled release matrices, have been well described in the literature, as has the use of delivering particulate delivery systems or particulate drug carriers such as microcapsules, lipid emulsions, microspheres, nanocapsules, liposomes, and lipoproteins into the circulating blood. However, local delivery of such micro drug delivery systems to a depth within the myocardium using endocardial catheter delivery and epicardial injection systems have not been described, and have many advantages that have not been foreseen.
Recently, local delivery to the heart has been reported of therapeutic macromolecular biological agents by Lazarous [Circulation, 1996, 94:1074-1082.], plasmids by Lin [Circulation, 1990; 82:2217-2221], and viral vectors by French [Circulation, Vol. 90, No 5, November 1994, 2414-2424] and Muhlhauser [Gene Therapy (1996) 3, 145-153]. March [Circulation, Vol. 89, No 5, May 1994, 1929-1933.] describes the potential for microsphere delivery to the vessels of the heart, such as to limit restenosis, and this approach has also been used for the delivery of bFGF by Arras [Margarete Arras et. al., The delivery of angiogenic factors to the heart by microsphere therapy, Nature Biotechnology, Volume 16, February 1998.] These approaches for microsphere delivery obstruct flow, and will be delivered preferentially to capillary beds which are well perfused. Further, these approaches do not deliver therapeutic agents to the interstitial spaces. None of this work recognizes the potential to use particulate drug delivery system to optimize local drug delivery at a depth within the myocardium. This art also does not recognize the potential such delivery systems have in treating disease substrates in the myocardium if delivered to an appropriate region of the myocardial interstitium.
Problems exist for delivering small molecules or lipophilic molecules which rapidly transport through the capillary wall, to well-perfused tissues such as the myocardium. These problems are due to the convective losses of the agents to the systemic circulation. By going rapidly across the capillary wall, the small molecules are rapidly carried away by the bloodstream. Local delivery of an easily transported molecule is difficult because local delivery concentrations are rapidly reduced at very small distances from the delivery site due to convective losses. Such easily transported agents cannot treat an effective area of tissue locally without raising the systemic concentrations of the agents to a therapeutic level.

This patent is subject to a terminal disclaimer.

Method of treating coronary arteries with perivascular delivery of therapeutic agents