A method of making an electroconductive pattern on a support is disclosed. The support is provided with a polymer layer containing a polythiophene, a polyanion and a di- or polyhydroxy organic compound. Said layer is characterized by an initial surface resistivity (SRi) having a value which is higher than 104 xcexa9/xe2x96xa1, or more preferably higher than 106 xcexa9/xe2x96xa1. By heating selected areas of the polymer layer, the surface resistivity of these areas is reduced to SRi/xcex94 wherein xcex94 is at least 10, preferably at least 103 and more preferable at least 105. The electroconductive pattern thus obtained can be used as an electronic circuit for making an electric or semiconductor device such as a printed circuit board, an integrated circuit, a display, an electroluminescent device or a photovoltaic cell.

The present invention relates to a method for making a electroconductive pattern in an organic polymer layer which is suitable as an electronic circuitry in an electric or semiconductor device.
Electric or semiconductor devices such as flat panel displays, photovoltaic cells or electrochromic windows typically contain a substrate provided with an indium tin oxide (ITO) layer as a transparent electrode. The coating of ITO is carried out by vacuum sputtering methods which involve high temperature conditions up to 250xc2x0 C., and therefore, glass substrates are generally used. The high cost of the fabrication methods and the low flexibility (pliability) and stretchability of such electrodes, due to the brittleness of the inorganic ITO layer as well as the glass substrate, limit the range of potential applications. As a result, there is a growing interest in making all-organic devices, comprising plastic resins as a substrate and organic electroconductive polymer layers as an electrode. Such plastic electronics allow to obtain low cost devices with new properties (Physics World, March 1999, p.25-39). Flexible plastic substrates can be provided with an electroconductive polymer layer by continuous roller coating methods (compared to batch process such as sputtering) and the resulting organic electrodes enable the fabrication of electronic devices characterised by a higher flexibility and a lower weight.
The production and the use of electroconductive polymers such as polypyrrole, polyaniline, polyacetylene, polyparaphenylene, polythiophene, polyphenylenevinylene, polythienylenevinylene and polyphenylenesulfide are well known in the art. EP-A-440 957 describes a method for preparing polythiophene in an aqueous mixture by oxidative polymerisation in the presence of a polyanion as a doping agent. In EP-A-686 662 it has been disclosed that highly conductive layers of polythiophene, coated from an aqueous coating solution, could be made by the addition of a di- or polyhydroxy and/or a carbonic acid, amide or lactam group containing compound in the coating solution of the polythiophene layer and by keeping the coated layer at elevated temperature, preferably between 100 and 250xc2x0 C., during preferably 1 to 90 seconds.
Coated layers of organic electroconductive polymers can be structured into patterns using the known wet-etching microlithography techniques. WO97/18944 describes a process wherein a positive or negative photoresist is applied on top of a coated layer of an organic electroconductive polymer, and after the steps of selectively exposing the photoresist to UV light, developing the photoresist, etching the electroconductive polymer layer and finally stripping the non-developed photoresist, a patterned layer is obtained. A similar technique has been described in Synthetic Metals, 22 (1988), p. 265-271 for the design of an all-organic thin-film transistor. Such methods are cumbersome as they involve many steps and require the use of hazardous chemicals. Research Disclosure No. 1473 (1998) describes photoablation as a method suitable for patterning organic electroconductive polymer layers, wherein the selected areas are removed from the substrate by laser irradiation. Such photoablation processes are convenient, dry, one-step methods but the generation of debris still requires a wet cleaning step and may contaminate the optics and mechanics of the laser structuring device. Some prior art methods also induce a difference of the optical density between electroconductive and non-conductive areas of the patterned surface, which should be avoided.
It is an object of the present invention to provide a convenient, dry, one-step method of patterning an electroconductive organic polymer layer which does not require a wet cleaning step and which does not influence the optical density of the polymer layer. This object is realized by the method of claim 1. Specific features for preferred embodiments of the invention are disclosed in the dependent claims.
Further advantages and embodiments of the present invention will become apparent from the following description.
All values of surface resistivity (SR) presented in this document are measured according to the following method. The sample is cut to obtain a strip having a length of 27.5 cm and a width of 35 mm. Electrodes are applied over the width of the strip at a distance of 10 cm from each other. The electrodes are made of a conductive polymer, ECCOCOAT CC-2 available from Emerson and Cumming Speciality polymers. A constant potential is then applied over said electrodes and the current flowing through the circuit is measured on a Pico-amperemeter KEITHLEY 485. SR in xcexa9/square (xcexa9/xe2x96xa1) is calculated from the measured values of potential and current, taking into account the geometry of the measurement.
The polythiophene layer used in the method of the present invention is similar to those described in EP-A-686 662. However, contrary to the method of EP-A-686 662, the coated layer is not dried or treated at elevated temperature, so that the initial surface resistivity (SRi) is kept at a high value of at least 104 xcexa9/xe2x96xa1, or more preferably at least 106 xcexa9/xe2x96xa1, i.e. the conductivity of the layer is insufficient to be suitable as an electrode. By heating selected areas (paths), hereinafter referred to as xe2x80x98image-wise heatingxe2x80x99, the SR of said areas is decreased to SRi/xcex94, wherein the factor xcex94 is at least 10, preferably at least 103 or even more preferably at least 105 so as to obtain a pattern of conductive and non-conductive areas which can be used as an electronic circuitry. Said electronic circuitry can be a relatively low-resolution circuitry as typically used in printed circuit boards or a high-resolution microcircuitry as used in integrated semiconductor devices. More applications of the present invention are indicated below.
Simulation experiments, wherein the above mentioned polymer layer is overall heated in an oven, indicate that a treatment at 200xc2x0 C. during 2 minutes suffices to reduce SRi by a factor xcex94 between 104 and 105. The thickness of the layer is not significantly influenced by such treatment which illustrates that the organic polymer layer can be rendered electroconductive by heat treatment without invoking ablation. So the method of the present invention is particularly distinguished from prior art methods in that no material is removed from the layer, i.e. the conducting and non-conducting areas are all located in the same plane which may be beneficial when used in devices wherein very thin layers are applied on the electrodes, e.g. organic light emitting polymer displays. Moreover, the method of the present invention allows to obtain an electroconductive pattern showing no substantial difference of optical density between conducting and non-conducting areas. As an alternative method, contrary to the method of the present invention, one may also obtain an electroconductive pattern by ablating selected areas of the polymer layer and then overall heating the remaining areas, thereby decreasing the SR value so as to render said remaining areas electroconductive. However, said alternative method also involves ablation and thus is characterized by the same problems as the prior art methods described above.
The polythiophene used in the method of this invention has preferably the following formula:
in which n is larger than 1 and each of R1 and R2 independently represents hydrogen or an optionally substituted C1-4 alkyl group or together represent an optionally substituted C1-4 alkylene group or an optionally substituted cycloalkylene group, preferably an ethylene group, an optionally alkyl-substituted methylene group, an optionally C1-12 alkyl- or phenyl-substituted ethylene group, a 1,3-propylene group or a 1,2-cyclohexylene group.
The preparation of such a polythiophene and of aqueous dispersions containing such a polythiophene and a polyanion is described in EP-A-440 957 and corresponding U.S. Pat. No. 5,300,575. Basically the preparation of polythiophene proceeds in the presence of polymeric polyanion compounds by oxidative polymerisation of 3,4-dialkoxythiophenes or 3,4-alkylenedioxythiophenes according to the following formula:
wherein R1 and R2 are as defined above.
Stable aqueous polythiophene dispersions having a solids content of 0.05 to 55% by weight and preferably of 0.1 to 10% by weight can be obtained by dissolving thiophenes corresponding to the formula above, a polyacid and an oxidizing agent in an organic solvent or preferably in water, optionally containing a certain amount of organic solvent, and then stirring the resulting solution or emulsion at 0 to 100xc2x0 C. until the polymerization reaction is completed. The polythiophenes formed by the oxidative polymerization are positively charged, the location and number of such positive charges being not determinable with certainty and therefore not mentioned in the general formula of the repeating units of the polythiophene polymer.
The oxidizing agents are those which are typically used for the oxidative polymerization of pyrrole as described in for example J. Am. Soc. 85, 454 (1963). Preferred inexpensive and easy-to-handle oxidizing agents are iron(III) salts, e.g. FeCl3, Fe(ClO4)3 and the iron(III) salts of organic acids and inorganic acids containing organic residues. Other suitable oxidizing agents are H2O2, K2Cr2O7, alkali or ammonium persulfates, alkali perborates, potassium permanganate and copper salts such as copper tetrafluoroborate. Air or oxygen can also be used as oxiding agents. Theoretically, 2.25 equivalents of oxidising agent per mol of thiophene are required for the oxidative polymerization thereof (J. Polym. Sci. Part A, Polymer Chemistry, Vol. 26, p.1287, 1988). In practice, however, the oxidizing agent is used in excess, for example, in excess of 0.1 to 2 equivalents per mol of thiophene.
The polyacid forms a polyanion or, alternatively, the polyanion can be added as a salt of the corresponding polyacids, e.g. an alkali salt. Preferred polyacids or salts thereof are polymeric carbonic acids such as poly(acrylic acid), poly((meth)acrylic acid) and poly(maleic acid) or polymeric sulphonic acids such as poly(styrene sulphonic acid) or poly(vinyl sulphonic acid). Alternatively, copolymers of such carbonic and/or sulphonic acids and of other polymerizable monomers such as styrene or acrylates can be used. Poly(styrene sulphonic acid) is especially preferred. The molecular weight of these polyanion forming polyacids is preferably between 1000 and 2xc3x97106, more preferably between 2000 and 5xc3x97105. These polyacids or their alkali salts are commercially available and can be prepared according to the known methods, e.g. as described in Houben-Weyl, Methoden der Organische Chemie, Bd. E20 Makromolekulare Stoffe, Teil 2, (1987), pp. 1141.
The polythiophene dispersions obtained according to the above method can then be used as basic ingredient of a coating solution. The coating solution can also comprise additional ingredients, such as one or more binders, one or more surfactants, spacing particles, UV-filters or IR-absorbers. Suitable polymer binders are described in EP-A 564 911. Such binders may be treated with a hardening agent, e.g. an epoxysilane as described in EP-A 564 911, which is especially suitable when coating on a glass substrate.
The coating solution can be applied to the substrate by any means known in the art: it can be spin-coated, sprayed or coated by any of the continuous coating techniques that are used to coat solutions on running webs, e.g. dip coating, rod coating, blade coating, air knife coating, gravure coating, reverse roll coating, extrusion coating, slide coating and curtain coating. An overview of these coating techniques can be found in the book xe2x80x9cModern Coating and Drying Technologyxe2x80x9d, Edward Cohen and Edgar B. Gutoff Editors, VCH publishers, Inc, New York, N.Y., 1992. It is also possible to coat simultaneously multiple layers by coatings technique such as slide coating and curtain coating. It is also possible to apply the coating solution to the substrate by printing techniques, e.g., ink-jet printing, gravure printing, flexo printing, or offset printing.
The coating solution is preferably applied to the substrate in such an amount that the coated polymer layer contains between 10 and 5000 mg of polythiophene per m2, more preferably between 100 and 500 mg of polythiophene per m2. The coated polymer layer is preferably dried at a temperature below 100xc2x0 C., more preferably below 70xc2x0 C. and even more preferably between 40xc2x0 C. so that the SR of the polymer layer is at least 104 xcexa9/xe2x96xa1, or more preferably at least 106 xcexa9/xe2x96xa1.
The coated polymer layer further comprises a di- or polyhydroxy organic compound, which can be added to the coating solution. Preferred examples of such di- or polyhydroxy organic compounds are sugar or sugar derivatives such as arabinose, saccharose, glucose, fructose and lactose, or di- or polyalcohols such as sorbitol, xylitol, mannitol, mannose, galactose, sorbose, gluconic acid, ethylene glycol, di- or tri(ethylene glycol), 1,1,1-trimethylol-propane, 1,3-propanediol, 1,5-pentanediol, 1,2,3-propanetriol, 1,2,4-butanetriol, 1,2,6-hexanetriol, or aromatic di- or polyalcohols such as resorcinol. The amount of these compounds in the coated layer may be between 10 and 5000 mg/m2, preferably between 50 and 1000 mg/m2.
The substrate used in the method of the present invention can be inorganic or organic. Suitable polymeric films are made of e.g. a polyester such as poly(ethylene terephthalate), poly(ethylene naphthalate), polystyrene, polyethersulphone, polycarbonate, polyacrylate, polyamide, polyimides, cellulosetriacetate, polyolefines, polyvinylchloride, etc. As inorganic substrates can be used silicon, ceramics, oxides, glass, polymeric film reinforced glass, glass/plastic laminates, e.g. as described in WO 99/21707 and WO 99/21708. The latter is a laminate of a flexible, thin glass and a plastic support, which is a highly suitable substrate for use in the present invention since such a material provides both a good dimensional stability as well as some flexibility. The substrate is preferably provided with an adhesion improving layer, whereon the above described coating solution can be applied.
The step of image-wise heating the polymer layer is preferably carried out by means of a scanning device such as a laser or a line-wise heating device such as a thermal head. Also other devices can be used, e.g. a heated stamp. The energy applied to the polymer layer during image-wise heating should be sufficiently high to decrease the SR value of the polymer layer so as to obtain electroconductive areas, but should not exceed a treshold value above which ablation or chemical processes are capable of substantially destroying the polymer layer.
Typical lasers which can be used in the method of the present invention are e.g. a He/Ne or Ar laser. Preferably, a laser emitting near infrared light having a wavelength in the range from about 700 to about 1500 nm is used, e.g. a semiconductor laser diode, a Nd:YAG or a Nd:YLF laser. The required laser power depends on the pixel dwell time of the laser beam, which is dependent on the scan speed (e.g. between 0.1 and 20 m/s, preferably between 0.5 and 5 m/s) and the spot diameter of the laser beam (defined at 1/e2 of maximum intensity e.g. between 1 and 100 xcexcm, preferably between 10 and 25 xcexcm). More details of the specific exposure parameters are given while discussing the examples below.
In order to improve the light absorption, a compound which is capable of converting light into heat may be added to the polymer layer. Useful compounds are for example organic dyes, carbon black, graphite, metal carbides, borides, nitrides, carbonitrides, or oxides. The polythiophene itself absorbs infrared light, so it may be unnecessary to add dyes or pigments when an infrared light source is used. The addition of a dye or pigment capable of absorbing visible light should even be avoided when the method of the present invention is to be used for making a transparent electrode. Alternatively, the support may absorb the incident light, e.g. when exposing a plastic support such as poly(ethylene terephthalate), to an excimer laser.
A typical thermal head for use in the method of the present invention contains a plurality of adjacent, microscopic heat-resistor elements, which convert electrical energy via the Joule effect into heat. Such thermal printing heads may be used in contact or, more preferred, close proximity with the polymer layer so as to transfer efficiently the heat to the polymer layer. The operating temperature of common thermal printheads is in the range of 300 to 400xc2x0 C. and the heating time per element may be less than 20 ms or even less than 1.0 ms, the pressure contact of the thermal printhead with the material being e.g. 200 to 500 g/cm2 to ensure a good transfer of heat.
The electroconductive pattern obtained by the method of the present invention can be used as an electronic circuit for making an electric or semiconductor device such as a printed circuit board, an integrated circuit, a display, an electroluminescent device or a photovoltaic cell. Preferred examples of a display are passive-matrix liquid crystal displays (LCDs) as well as active-matrix LCDs such as thin-film-transistor (TFT) displays. Particular examples are twisted nematic (TN), supertwisted nematic (STN), double supertwisted nematic (DSTN), retardation film supertwisted nematic (RFSTN), ferroelectric (FLC), guest-host (GH), polymer-dispersed (PF), polymer network (PN) liquid crystal displays. Emissive flat panel display types which may benefit from the present invention are e.g. plasma displays (PDs), field emission displays (FEDs) and so-called organic light-emitting polymer displays (OLEDs).
In OLEDs electrons and holes are injected from a cathode and anode respectively into an electroluminescent material, e.g. an electroluminescent polymer such as poly(p-phenylenevinylene) (PPV) and its derivatives, and then recombine to an exciton which relaxes to the ground state by radiative decay. Such an OLED typically comprises the following layers:
a reflecting cathode, e.g. a low-work function metal layer such as evaporated Ca.
an electroluminescent layer, e.g. PPV; other suitable electroluminescent compounds are described in e.g. xe2x80x9cOrganische Leuchtdiodenxe2x80x9d, Chemie in unserer Zeit, 31. Jahrg. 1997, No.2, p.76-86.
an hole-injection layer
an transparent anode
a transparent substrate
The hole-injection layer as well as the anode layer can be patterned layers obtained according to the method of the present invention.
The patterned electrode obtained by the method of the present invention can also be used for screening electromagnetic radiation or earthing electric charges, for making touch screens, radio frequency identification tags, electrochromic windows and in imaging systems, e.g. silver halide photography or electrophotography. Also a device such as the electronic book described in WO 97/04398 may particularly benefit from the flexible electrode of the present invention. Even more applications are described in WO 97/18944.

Method of making an electroconductive pattern on a support


An electronic power supply device is provided for light-emitting diodes (LEDs), which employs electronic control to maintain the LEDs within the rated ranges of current, voltage and temperature and provides the LEDs with extremely stable current, voltage and temperature. Meanwhile, the power supply device is effective in confining the LEDs within the rated ranges of voltage, current, and temperature so that the excellent electronics protection and design of logic device realized by the power supply device effectively overcomes aging/deterioration of LEDs caused by exceeding voltage and current and burning out due to exceeding temperature and also effectively pushes the rated current and voltage of a (low-power) LED module toward the maximum values to provide the greatest luminous efficiency for upgrading the applications of the LEDs to the primary grade of lighting.

(a) Technical Field of the Invention
The present invention relates to an electronic power supply device for light-emitting diodes (LEDs), which is aimed to provide an electronic power supply device for LEDs to make a breakthrough for the limitations imposed to the currently available (low-power) LEDs due to restriction and stability in voltage, current and temperature in order to make the application and lighting efficiency of the (low-power) LEDs well satisfying the general requirements for regular lighting purposes; thus the present invention is provided to enhance the lighting efficiency of the low-power LEDs by offering features of control, detection, protection, and brightness adjustment and maintaining stable effect of current, voltage and temperature within the rated ranges of voltage, current, and temperature to thereby improve the performance utilization efficiency of the whole LED module and make the low-power LEDs fully exploiting the maximum performance utilization efficiency and brightness efficiency so as to effectively overcome the operation problems of high-power LEDs caused by exceeding high temperature and also to provide the low-power LEDs with new fields of application by upgrading the low-power LEDs to the primary grade of lighting application. Accordingly, the present invention provides an electronic power supply device for LEDs, which is applicable to both high-power LEDs and low-power LEDs for enhancement of brightness efficiency, performance utilization efficiency, and temperature controllability.
For high-power LEDs, their specifications are usually set on the basis of wattages, such as 1 W, 3 W and 5 W. Thus, the rated voltage and current of the high-power LEDs are high and the brightness that can be given off is correspondingly heightened. For the current technology, if heat dissipation is temporarily not taken into consideration, projects of using the high-power LEDs in primary lighting device are available. Such projects are the important concerns for the manufacturers in the related fields.
In view of the characteristics of the high-power LEDs, since they have high rated voltage and current, high radiation of thermal energy occurs. For the current development of high-power LEDs, the problem heat dissipation is always troubling the manufacturers and no feasible solution for optimum and efficient dissipation of heat is available. Thus, power consumption and thermal issue are major factors for the success of the high-power LEDs. However, these two are of a vicious circle relationship and are the factor for the failure of the high-power LEDs.
For the applications of the high-power LEDs, the most important issue is the dissipation of heat generated thereby. If the heat cannot be properly dissipated, once the temperature gets beyond the rated range of temperature, the LEDs may get burnt out or aging thereof is accelerated. This is true for both low-power and high-power LEDs. Once aging occurs, the brightness of the LEDs get seriously deteriorated, which is thus irreversibly damaged. Thus, the heat dissipation issue is the most important challenge for the manufacturers and engineers, and various proposals have been made. Such proposed thermal solutions for high-power LEDs are of two categories, the active heat dissipation mechanism and the passive heat dissipation mechanism. Other types of heat dissipation, such as liquid heat dissipation device disclosed in UP patent documents, which is applicable to bulb-shaped LED structure, is also available.
For low-power LEDs, since the rated voltage and current are low, their power consumption and heat generated are small. Currently, the low-power LEDs are mature market products, but they are still of poor brightness efficiency and the applications thereof are dependent upon the factors including constituent number of the LEDs, the voltage, the current, and the heat dissipation gap. Thus, they are not still applicable in the field of lighting.
Although the present invention is applicable to the range of high-power LEDs for realizing control, detection, protection, brightness adjustment and for being well maintained in the rated ranges of voltage, current and temperature, to provide extremely stable current, voltage and thermal effect and thus enhancing the performance utilization efficiency and maximum brightness efficiency of the whole LED module, yet incorporation with a heat dissipation mechanism for accelerating heat dissipation is preferred. For low-power LEDs, a novel and revolutionary application can be realized. First, according to the characteristics of the low-power LEDs, since the rated voltage and current are low, the power consumption and temperature are low and thus, the issues of power saving and low thermal efficiency can be alleviated and overcome. Thus, the present invention is made on the basis of the following aspects.
The first aspect of the present invention is to provide a power supply system of extremely stable voltage and current within the rated ranges of voltage and current of the LEDs (including both high-power and low-power LEDs) so that an LED module can have extremely stabilized lighting efficiency for effectively controlling the thermal issue induced.
The second aspect of the present invention is to up-push the voltage and current of LEDs within the rated voltage and current and temperature of the LEDs (including both high-power and low-power LEDs) and under the condition of ensuring stable power supply, so that the brightness efficiency and the temperature of the LEDs can be of optimum (maximum) level of matching within the normal operation values and temperature.
The third aspect of the present invention is to employ a photo-coupling circuit for detection the supplied current and voltage and the energy conversion efficiency within the rated voltage and current and temperature of the LEDs (including both high-power and low-power LEDs) and under the condition of ensuring stable power supply and enhanced brightness efficiency, so that any minor variation can be effectively changed and handled to provide intelligent functional modulation capability to further realize protection of LED modules and the power supply, leading to extension of service life of both.
The fourth aspect of the present invention is to monitor the temperature of working environment (which means extremely bad and extremely hot working environment here) within the rated voltage and current and temperature of the LEDs (including both high-power and low-power LEDs) and under the condition of ensuring stable power supply and enhanced brightness efficiency, in order to first use an effective and stable process to reduce the current and voltage for protecting the power supply device and maintaining the normal operation of the LED module and then, after the power supply dropping the voltage and current to resume the normal operation temperature, use an effective and stable process to increase the current and voltage, so that a humanized control mechanism can be realized (such changes taking place in a naked-eye invisible fashion) for protecting the LED module and extending service life thereof.
The fifth aspect of the present invention is to monitor the temperature of working environment (which means extremely bad and extremely cold working environment here) within the rated voltage and current and temperature of the LEDs (including both high-power and low-power LEDs) and under the condition of ensuring stable power supply and enhanced brightness efficiency, in order to activate a system heating module for pre-heating the circuit device to realize protection of the LED module and extending service life thereof.
The sixth aspect of the present invention is to combine an LED brightness adjustment module to the load end, within the rated voltage and current and temperature of the LEDs (including both high-power and low-power LEDs) and under the condition of ensuring stable power supply and enhanced brightness efficiency, in order to realize stepless adjustment of brightness.
Based on the above description, the present invention provides an electronic power supply device for LEDs, which facilitates the applications of LED modules to various lighting and indication for enhancing the operation and model of LED module and this is particularly a novel way of application for low-power LEDs. Meanwhile, the present invention allows significant enhancement of brightness and efficiency of LEDs within the rated ranges of voltage, current and temperature and under the condition for realizing control, detection, protection, brightness adjustment and providing stable current and voltage and temperature effect, to thereby significantly improve brightness efficiency of LED module and effectively control and protect the power supply device and the LED module for eventually achieving the goals of power saving and extended service life.
(b) Description of the Prior Art
In the field of lighting, household lighting devices have evolved from the early stage of incandescent bulbs of high wattage to lamp tubes (fluorescent tubes) and further evolved to the energy-saving lamp tubes, such as PL tubes, energy-saving bulbs (with stabilizer). This change to the household lighting device was simply happening in a short periods of tens of years and a significant progress and innovation occurs for the lighting devices.
Recently, the era of environment conservation and development of substitute energy arrives; and the energy-saving lighting devices, which are most commonly used recently, namely the fluorescent tube, the PL tubes, and the energy-saving bulbs, are subjected to challenge for saving of power for the amount of energy consumed by these lighting devices is dependent upon the quantity thereof. A great quantity of the lighting devices certainly causes a great amount of energy consumed. Taking the fluorescent tube as an example, the power consumption for use of four 20 W fluorescent tubes can be calculated as 20 W×4=80 W. This way of calculation is also applicable to PL tubes and bulbs. Further, in the case of PL tubes and power-saving bulbs with stabilizer, the power consumption is less than the traditional lighting bulbs, but a by-product of "high temperature" is caused, which leads to additional load and/or requirement of installation of air-conditioning systems. An additional safety problem also rises for all the lighting bulbs or tubes are made of glass, which is of a potential risk of explosion and they are considered highly dangerous objects in installation, waste handling, recycling and transportation.
In view of the above problems, low-power light-emitting diodes (LEDs) provide a feasible solution and are becoming a prosperous and promising substitute for the traditional lighting devices. According to reports and articles describing the low-power LEDs as a substitute for the traditional lighting, due to the advantages of having high brightness, capability of long distance projection, high condensability, and low power consumption, the low-power LEDs are quite a solution for lighting that meets the general needs of human society and environmental conservation. The most important is the extreme saving of power that the LEDs can achieve and the availability of material and low costs for making the LEDs, which give the LEDs the most important advantages of reduced cost. Thus, the LEDs is of the most promising commercial application in the filed of lighting.
The LEDs are operated with direct current (DC) power. Thus, for the operation of the LEDs, if battery or cell based DC power supply is excluded and alternate current (AC) power mode is taken into consideration, the operation of LEDs would require conversion of the AC into DC power before the power can be supplied to the LEDs. This is the general way and construction that the application of the LEDs is taken. For example, as shown in FIGS. 1-3 of the attached drawings, conventionally, a power supply device is employed to realize power supply to the LEDs, and the known power supply device generally comprises a bridge rectifier A1, which converts 110V-220V AC into DC of 12V or 9V or 3V. Then, a capacitor A2 converts the waveform into DC pulses of positive cycles of Sine wave to thereby complete the conversion.
However, in respect of the high-power LEDs, since the output voltage and current (around 3 A) are still of high levels, for a large-sized high-power LED module, a bulky power supply device is needed to supply power of regulated voltage and stable current. On the other hand, for the LED module at a load end, since the output voltage and current are of high levels, remarkable variation of instantaneous voltage, current, resistance and temperature may occur, making the load end very unstable. Further, since the LED module is usually of a large scale and compact design, high temperature often result. For design of poor heat dissipation, high temperature would result again and the high temperature itself leads to instability of instantaneous voltage and current, which once again result influence of the LED module of the load end.
Once the voltage and current of the supplied power or the temperature caused thereby exceed the rated values specified to the LEDs, aging of the LEDs, such as deterioration of lighting performance and reduction of brightness, may occur, or even worse, the LEDs may get burnt out. Thus, application of the high-power LEDs in the field of lighting will inevitably encounter the problems associated with current, voltage and temperature. Consequently, the stability and service of lighting device using the high-power LEDs are still doubtful.
For low-power LEDs, since the output voltage and current are small, the temperature caused is low, but the lighting performance is apparently insufficient. Thus, conventionally, the operation mode of the low-power LEDs is simply making straightforward and simple conversion by using diodes before the power is employed to drive the low-power LEDs. Further, to ensure the low-power LEDs well within the rated ranges of current, voltage, and temperature, the lighting efficiency and performance of the low-power LEDs are kept low.
If the number of LEDs at the load end is significantly increased and the lighting efficiency of the low-power LEDs is enhanced and the LED module of the load end adopts a large-scale and compact design, then the required output voltage and current will be increased, and the temperature is also increased. Thus, the same old problems of the high-power LED rise again. Thus, the three factors of current, voltage, and temperature caused are the primaries that are considered in the present invention.

Electronic power supply device for light-emitting diode


There is disclosed a pneumatic tire having a rubber component comprising a sulfur cured rubber composition composed of, based on 100 parts by weight of rubber (phr):

U.S. Pat. No. 6,031,053 discloses a thermoplastic elastomer that is a block styrene butadiene copolymer. The block copolymer has at least one block A having polymerized units of a styrene and forming a rigid phase and at least one elastomeric block B/A having polymerized units of both styrene and butadiene and forming a flexible phase. In U.S. Pat. No. 5,880,156, these thermoplastic elastomers are disclosed as being dispersed as particles in a continuous phase of polystyrene or a styrene copolymer containing up to 50 percent of comonomers to form an expandable styrene polymer for elastic polystyrene forms. These expandable styrene polymers are prepared by polymerization of styrene in the presence of the block copolymers and impregnation with a blowing agent.
The present invention relates to a pneumatic tire having a rubber component containing a block styrene butadiene copolymer.
There is disclosed a pneumatic tire having a rubber component comprising a sulfur cured rubber composition composed of, based on 100 parts by weight of rubber (phr):
(a) 99 to 50 parts by weight of a first rubber containing olefinic unsaturation; and
(b) 1 to 50 parts by weight of a second rubber which is different from said first rubber and which is an elastomeric block copolymer of
(1) from 15 to 65 percent by weight, based on the total block copolymer, of butadiene, and
(2) from 35 to 85 percent by weight, based on the total block copolymer, of styrene, which block copolymer has:
(a) at least two blocks A which have polymerized units of styrene, a glass transition temperature Tg above 25xc2x0 C. and forms a rigid phase, and
(b) at least one elastomeric block which is composed of about 25 to 70 percent by weight of butadiene and 75 to 30 percent by weight of styrene, and which has polymerized B/A units of styrene and butadiene in a random structure; a glass transition temperature Tg from xe2x88x9250xc2x0 C. to 25xc2x0 C., and is located between two blocks A and forms a flexible phase, and the amount of the rigid phase accounts for 5 to 40 percent by volume.
The present invention relates to a pneumatic tire containing an elastomeric block copolymer comprising at least one block A which has polymerized units of a styrene and forms a rigid phase and at least one elastomeric block B/A which has polymerized units of styrene and of butadiene and forms a flexible phase, the glass transition temperature Tg of the block A being above 25xc2x0 C. and the phase volume ratio of black A to block B/A being chosen so that the amount of the rigid phase in the total block copolymer is from 5 to 40 percent by volume and the amount of the diene in the total block copolymer is less than 50 percent by weight. These elastomeric block copolymers and their preparation are disclosed in U.S. Pat. No. 6,031,053 which is incorporated herein in its entirety.
The block copolymer may be of, for example, one of the general formula 1 to 11:
where A is the styrene block and B/A is the flexible phase, i.e. the block composed of random butadiene and styrene units, X is a radical of an n-functional initiator, Y is the radical of a m-functional coupling agent and m and n are natural numbers from 1 to 10.
A preferred block copolymer is one of the general formula A-B/Axe2x80x94A, X-[-B/Axe2x80x94A]2 or Y-[-B/Axe2x80x94A]2 (the meanings of the abbreviations are as above) and a particularly preferred block copolymer is one whose flexible phase is divided into blocks
whose styrene/butadiene ratio differs in the individual blocks B/A or changes continuously within a block within the limits (B/A)1xe2x86x92(B/A)2, the glass transition temperature Tg of each sub-block being below 25xc2x0 C.
A block copolymer which has a plurality of blocks B/A and/or A having different molecular weights per molecule is likewise preferred.
The B/A block is composed of about 75 to 30 percent by weight of styrene and 25 to 70 percent by weight of butadiene. A flexible block particularly preferably has a butadiene content of from 35 to 70 percent and a styrene content of from 65 to 30 percent.
In the case of the monomer combination styrene/butadiene, the amount of the diene in the total block copolymer is 15 to 65 percent by weight and that of the vinylaromatic component is correspondingly 85 to 35 percent by weight. Butadiene/styrene block copolymer having a monomer composition comprising 25 to 60 percent by weight of diene and 75 to 40 percent by weight of vinylaromatic compound are particularly preferred.
The block copolymer may be prepared by anionic polymerization in a nonpolar solvent with the addition of a polar cosolvent. The cosolvent acts as a Lewis base toward the metal cation. Preferably used solvents are aliphatic hydrocarbons, such as cyclohexane or methylcyclohexane. Polar aprotic compounds, such as ethers and tertiary amines, are preferred as Lewis bases. Examples of particularly effective ethers and tetrahydrofuran and aliphatic polyethers, such as diethylene glycol dimethyl ether. Examples of tertiary amines are tributylamine and pyridine. The polar cosolvent is added to the nonpolar solvent in a small amount, for examples 0.5 to 5 percent by volume. Tetrahydrofuran in an amount of 0.1 to 0.3 percent by volume is particularly preferred. Experience has shown that an amount of about 0.2 percent by volume is sufficient in most cases.
The copolymerization parameters and the amount of 1,2- and 1,4-bonds of the diene units are determined by the metering and structure of the Lewis base. The novel polymers contain, for example, 15 to 50 percent of 1,2-bonds and 85 to 60 percent of 1,4-bonds, based on all diene units.
The anionic polymerization is initiated by means of organometallic compounds. Compounds of the alkali metals, particularly lithium, are preferred. Examples of initiators are methyllithium, ethyllithium, propyllithium, n-butyllithium, sec-butyllithium and tert-butyllithium. The organometallic compound is added as a solution in a chemically inert hydrocarbon. The amount metered depends on the desired molecular weight of the polymer but is as a rule from 0.002 to 5 mol percent, based on the monomers.
The polymerization temperature may be from 0 to 130xc2x0 C., preferably from 30 to 100xc2x0 C.
The amount of volume of the flexible phase in the solid is of decisive importance for the mechanical properties. According to the invention, the amount by volume of the flexible phase composed of butadiene and styrene sequences is 60 to 95, preferably 70 to 90, particularly preferably 80 to 90 percent by volume.
It should be pointed out that there is no strict correlation between the above mentioned ratios of styrene and butadiene, the above mentioned limits of the phase volumes and the composition which arises from the novel ranges of the glass transition temperature, since the relevant numbers in each case are numerical values rounded up to the nearest tens unit. Any correlation is likely to be merely accidental.
The volume fraction of the two phases can be measured by means of high-contrast electron microscopy or solid-state NMR spectroscopy. The amount of styrene blocks can be determined by precipitation and weight following osmium degradation of the polybutadiene content. The future phase ratio of a polymer can also be calculated from the amounts of monomers used if polymerization is taken to completion every time.
In addition, it is to be pointed out (cf. J. Brandrup, E. H. Immergut Polymer Handbook, John Wiley, N.Y.) that the densities of styrene/butadiene copolymers can be calculated approximately from the mass fractions of the monomers; thus, the density of polybutadiene (obtained by anionic polymerization) is 0.895 g/ml and the density of polystyrene is about 1.05 g/ml (mean value), whereas the density is stated as 0.933 for a styrene/butadiene copolymer (SB rubber) containing 23.5 percent of styrene. The calculated density would b 0.960.
For the purposes of the present invention, the block copolymer is unambiguously defined by the quotient of the volume fraction as a percentage of the flexible phase formed from the B/A blocks and the fraction of butadiene units in the flexible phase, which is from 25 to 70 percent by weight for the combination styrene/butadiene.
The glass transition temperature (Tg) is influenced by the random incorporation of the vinylaromatic compounds in the flexible block of the block copolymer and the use of Lewis bases during the polymerization. A glass transition temperature of from xe2x88x9250 to +25xc2x0 C., preferably from xe2x88x9250 to +5xc2x0 C. is typical.
The molecular weight of block A is in general from 1,000 to 200,000, preferably from 3,000 to 80,000, g/mol. Within a molecule, A blocks may have different molecular weights.
The molecular weight of block B/A is usually from 2,000 to 250,000, preferably from 5,000 to 150,000, g/mol.
As in the case of block A, block B/A too may assume different molecular weight values within a molecule.
The coupling center X is formed by the reaction of the living anionic chain ends with a bifunctional or polyfunctional coupling agent. Examples of such compounds are given in U.S. Pat. Nos. 3,985,830, 3,280,084, 3,637,554 and 4,091,053. For example, epoxidized glycerides, such as epoxidized linseed oil or soybean oil, are preferably used; divinylbenzene is also suitable. Dichlorodialkylsilanes, dialdehydes, such as terephthalaldephyde, and esters, such as ethyl formate or ethyl benzoate, are particularly suitable for the dimerization.
Preferable polymer structures are A-B/Axe2x80x94A, X-[B/Axe2x80x94A]2 and Y-[-B/Axe2x80x94A]2, where the random block B/A itself may in turn be divided into blocks B1/A1-B2/A2-B3/A3- . . . The random block preferably consists of from 2 to 15, particularly preferably from 3 to 10, random subblocks. The division of the random block B/A into as many subblocks Bn/An as possible has the decisive advantage that the B/A block as a whole behaves like a virtually perfect random polymer even in the case of a composition gradient within a subblock Bn/An, which is difficult to avoid in the anionic polymerization under practical conditions (see below). It is therefore appropriate to add less than the theoretical amount of Lewis base, which increases the proportion of the 1,4-diene bonds, reduces the glass transition temperature Tg and decreases the susceptibility of the polymer to crosslinking. A larger or smaller amount of subblocks may be provided with a high diene content. As a result of this, the polymer retains a residual toughness even below the glass transition temperature of the predominate B/A blocks and does not become completely brittle.
The block copolymers have a high oxygen permeation Po and water vapor permeation Pw of more than 2,000 [cm30.100 xcexcm/m2xc2x7dxc2x7bar] and above 10 [g 100 xcexcm/m2xc2x7dxc2x7bar], respectively, Po indicating the amount of oxygen in cm3, and Pw the amount of water vapor in grams, which passes through 1 m2 of film having a standard thickness of 100 xcexcm per day and per bar partial pressure difference.
The polymerization is carried out in a plurality of stages and, in the case of monofunctional initiation, is begun, for example, with the preparation of the rigid block A. A part of the monomers is initially taken in the reactor and the polymerization is initiated by adding the initiator. In order to achieve a defined chain structure which can be calculated from the monomer and initiator does, it is advisable to continue the process to a high conversion (above 99 percent) before the second monomer addition. However, this is not absolutely essential.
The sequence of the monomer addition depends on the chosen block structure. In the case of monofunctional initiation, for example, the styrene is first either initially taken or directly metered in. Thereafter, butadiene and styrene should be added as far as possible simultaneously. The random structure and the composition of the block B/A are determined by the ratio of butadiene to styrene, the concentration and the chemical structure of the Lewis base and the temperature. According to the invention, the diene accounts for from 50 percent by weight relative to the total material, including styrene. Block A can then be polymerized by adding the styrene. Instead, required polymer blocks may also be bonded to one another by a coupling reaction. In the case of bifinctional initiation, the B/A block is first synthesized, followed by the A block.
The further working up is carried out by the conventional methods. It is advisable to employ a stirred kettle and to protonate the carbanions with an alcohol, such as isopropanol, to render the mixture weakly acidic in the usual manner with CO2/water before the further working up, to stabilize the polymer with an antioxidant and a free radical acceptor (commercial products, such as trisnonylphenyl phosphite (TNPP) or xcex1-tocopherol (vitamin E), or products obtainable under the trade names Irganox 1076 or Irganox 3052, to remove the solvent by the usual methods, and to carry out extrusion and granulation. As in the case of other rubber types, the granules can be prevented from sticking together by means of an antiblocking agent, such as Acrawax(copyright), Besquare(copyright) or Acrosil(copyright).
Commercially available forms the above block copolymers may be obtained from BASF AG. For example, a butadiene-styrene block copolymer having the structure S-B/Sxe2x80x94S with 26 percent by volume of polystyrene blocks is sold under the designation STYROFLEX(copyright). One particular butadiene-styrene block copolymer is sold under the designation STYROFLEX(copyright) BX 6105.
As indicated above, from 1 to 50 parts by weight of the rubber is the elastomeric block copolymer. Preferably, from 15 to 50 parts by weight is the elastomeric block copolymer. Accordingly, from 99 to 50 phr is the first rubber containing olefinic unsaturation. Preferably, from 50 to 85 parts by weight is a rubber (also known herein as the first rubber) which is different from the blade copolymer and contains olefinic unsaturation.
The phrase xe2x80x9crubber or elastomer containing olefinic unsaturationxe2x80x9d is intended to include both natural rubber and its various raw and reclaim forms as well as various synthetic rubbers. In the description of this invention, the terms xe2x80x9crubberxe2x80x9d and xe2x80x9celastomerxe2x80x9d may be used interchangeably, unless otherwise prescribed. The terms xe2x80x9crubber compositionxe2x80x9d, xe2x80x9ccompounded rubberxe2x80x9d and xe2x80x9crubber compoundxe2x80x9d are used interchangeably to refer to rubber which has been blended or mixed with various ingredients and materials and such terms are well known to those having skill in the rubber mixing or rubber compounding art. Representative synthetic polymers are the homopolymerization products of butadiene and its homologues and derivatives, for example, methylbutadiene, dimethylbutadiene and pentadiene as well as copolymers such as those formed from butadiene or its homologues or derivatives with other unsaturated monomers. Among the latter are acetylenes, for example, vinyl acetylene; olefins, for example, isobutylene, which copolymerizes with isoprene to form butyl rubber; vinyl compounds, for example, acrylic acid, acrylonitrile (which polymerize with butadiene to form NBR), methacrylic acid and styrene, the latter compound polymerizing with butadiene to form SBR, as well as vinyl esters and various unsaturated aldehydes, ketones and ethers, e.g., acrolein, methyl isopropenyl ketone and vinylethyl ether. Specific examples of synthetic rubbers include neoprene (polychloroprene), polybutadiene (including cis-1,4-polybutadiene), polyisoprene (including cis-1,4-polyisoprene), butyl rubber, halobutyl rubber such as chlorobutyl rubber or bromobutyl rubber, styrene/isoprene/butadiene rubber, copolymers of 1,3-butadiene or isoprene with monomers such as styrene, acrylonitrile and methyl methacrylate, as well as ethylene/propylene terpolymers, also known as ethylene/propylene/diene monomer (EPDM), and in particular, ethylene/propylene/dicyclopentadiene terpolymers. Additional examples of rubbers which may be used include a carboxylated rubber, silicon-coupled and tin-coupled star-branched polymers. The preferred rubber or elastomers are polybutadiene and SBR.
In one aspect the rubber to be combined with the block copolymer is preferably of at least two of diene based rubbers. For example, a combination of two or more rubbers is preferred such as cis 1,4-polyisoprene rubber (natural or synthetic, although natural is preferred), 3,4-polyisoprene rubber, styrene/isoprene/butadiene rubber, emulsion and solution polymerization derived styrene/butadiene rubbers, cis 1,4-polybutadiene rubbers and emulsion polymerization prepared butadiene/acrylonitrile copolymers.
In one aspect of this invention, an emulsion polymerization derived styrene/butadiene (E-SBR) might be used having a relatively conventional styrene content of about 20 to about 28 percent bound styrene or, for some applications, an E-SBR having a medium to relatively high bound styrene content, namely, a bound styrene content of about 30 to about 45 percent.
When used in the tire tread, the relatively high styrene content of about 30 to about 45 for the E-SBR can be considered beneficial for a purpose of enhancing traction, or skid resistance. The presence of the E-SBR itself is considered beneficial for a purpose of enhancing processability of the uncured elastomer composition mixture, especially in comparison to a utilization of a solution polymerization prepared SBR (S-SBR).
By emulsion polymerization prepared E-SBR, it is meant that styrene and 1,3-butadiene are copolymerized as an aqueous emulsion. Such are well known to those skilled in such art. The bound styrene content can vary, for example, from about 5 to about 50 percent. In one aspect, the E-SBR may also contain acrylonitrile to form a terpolymer rubber, as E-SBAR, in amounts, for example, of about 2 to about 30 weight percent bound acrylonitrile in the terpolymer.
Emulsion polymerization prepared styrene/butadiene/acrylonitrile copolymer rubbers containing about 2 to about 40 weight percent bound acrylonitrile in the copolymer are also contemplated as diene based rubbers for use in this invention.
The solution polymerization prepared SBR (S-SBR) typically has a bound styrene content in a range of about 5 to about 50, preferably about 9 to about 36, percent. The S-SBR can be conveniently prepared, for example, by organo lithium catalyzation in the presence of an organic hydrocarbon solvent.
A purpose of using S-SBR is for improved tire rolling resistance as a result of lower hysteresis when it is used in a tire tread composition.
The 3,4-polyisoprene rubber (3,4-PI) is considered beneficial for a purpose of enhancing the tire""s traction when it is used in a tire tread composition. The 3,4-PI and use thereof is more fully described in U.S. Pat. No. 5,087,668 which is incorporated herein by reference. The Tg refers to the glass transition temperature which can conveniently be determined by a differential scanning calorimeter at a heating rate of 10xc2x0 C. per minute.
The cis 1,4-polybutadiene rubber (BR) is considered to be beneficial for a purpose of enhancing the tire tread""s wear, or treadwear. Such BR can be prepared, for example, by organic solution polymerization of 1,3-butadiene. The BR may be conveniently characterized, for example, by having at least a 90 percent cis 1,4-content.
The term xe2x80x9cphrxe2x80x9d as used herein, and according to conventional practice, refers to xe2x80x9cparts by weight of a respective material per 100 parts by weight of rubber, or elastomer.xe2x80x9d
In addition to the block copolymer and elastomer in the rubberized component of the tire, conventional fillers may be also present. The amount of such conventional fillers may range from 10 to 250 phr. Preferably, the filler is present in an amount ranging from 20 to 100 phr.
The commonly employed siliceous pigments which may be used in the rubber compound include conventional pyrogenic and precipitated siliceous pigments (silica), although precipitated silicas are preferred. The conventional siliceous pigments preferably employed in this invention are precipitated silicas such as, for example, those obtained by the acidification of a soluble silicate, e.g., sodium silicate.
Such conventional silicas might be characterized, for example, by having a BET surface area, as measured using nitrogen gas, preferably in the range of about 40 to about 600, and more usually in a range of about 50 to about 300 square meters per gram. The BET method of measuring surface area is described in the Journal of the American Chemical Society, Volume 60, Page 304 (1930).
The conventional silica may also be typically characterized by having a dibutylphthalate (DBP) absorption value in a range of about 100 to about 400, and more usually about 150 to about 300.
The conventional silica might be expected to have an average ultimate particle size, for example, in the range of 0.01 to 0.05 micron as determined by the electron microscope, although the silica particles may be even smaller, or possibly larger, in size.
Various commercially available silicas may be used, such as, only for example herein, and without limitation, silicas commercially available from PPG Industries under the Hi-Sil trademark with designations 210, 243, etc; silicas available from Rhone-Poulenc, with, for example, designations of Z1165MP and Z165GR and silicas available from Degussa AG with, for example, designations VN2 and VN3, etc.
Commonly employed carbon blacks can be used as a conventional filler. Representative examples of such carbon blacks include N110, N121, N220, N231, N234, N242, N293, N299, S315, N326, N330, M332, N339, N343, N347, N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990 and N991. These carbon blacks have iodine absorptions ranging from 9 to 145 g/kg and DBP No. ranging from 34 to 150 cm3/100 g.
It may be preferred to have the rubber composition for use in the tire component to additionally contain a conventional sulfur containing organosilicon compound. Examples of suitable sulfur containing organosilicon compounds are of the formula:
Z-Alk-Sn-Alk-Zxe2x80x83xe2x80x83(15)
in which Z is selected from the group consisting of
where R1 is an alkyl group of 1 to 4 carbon atoms, cyclohexyl or phenyl; R2 is alkoxy of 1 to 8 carbon atoms, or cycloalkoxy of 5 to 8 carbon atoms; Alk is a divalent hydrocarbon of 1 to 18 carbon atoms and n is an integer of 2 to 8.
Specific examples of sulfur containing organosilicon compounds which may be used in accordance with the present invention include: 3,3xe2x80x2-bis(trimethoxysilylpropyl)disulfide, 3,3xe2x80x2-bis (triethoxysilylpropyl)disulfide, 3,3xe2x80x2-bis(triethoxysilylpropyl)tetrasulfide, 3,3xe2x80x2-bis(triethoxysilylpropyl)octasulfide, 3,3xe2x80x2-bis(trimethoxysilylpropyl)tetrasulfide, 2,2xe2x80x2-bis(triethoxysilylethyl)tetrasulfide, 3,3xe2x80x2-bis(trimethoxysilylpropyl)trisulfide, 3,3xe2x80x2-bis(triethoxysilylpropyl)trisulfide, 3,3xe2x80x2-bis(tributoxysilylpropyl)disulfide, 3,3xe2x80x2-bis(trimethoxysilylpropyl)hexasulfide, 3,3xe2x80x2-bis(trimethoxysilylpropyl)octasulfide, 3,3xe2x80x2-bis(trioctoxysilylpropyl)tetrasulfide, 3,3xe2x80x2-bis(trihexoxysilylpropyl)disulfide, 3,3-bis(tri-2xe2x80x3-ethylhexoxysilylpropyl)trisulfide, 3,3xe2x80x2-bis(triisooctoxysilylpropyl)tetrasulfide, 3,3xe2x80x2-bis(tri-t-butoxysilylpropyl)disulfide, 2,2xe2x80x2-bis(methoxy diethoxy silyl ethyl)tetrasulfide, 2,2xe2x80x2-bis(tripropoxysilylethyl)pentasulfide, 3,3xe2x80x2-bis(tricyclonexoxysilylpropyl)tetrasulfide, 3,3xe2x80x2-bis(tricyclopentoxysilylpropyl)trisulfide, 2,2xe2x80x2-bis(tri-2xe2x80x3-methylcyclohexoxysilylethyl)tetrasulfide, bis(trimethoxysilylmethyl)tetrasulfide, 3-methoxy ethoxy propoxysilyl 3xe2x80x2-diethoxybutoxy-silylpropyltetrasulfide, 2,2xe2x80x2-bis(dimethyl methoxysilylethyl)disulfide, 2,2xe2x80x2-bis(dimethyl sec.butoxysilylethyl)trisulfide, 3,3xe2x80x2-bis(methyl butylethoxysilylpropyl)tetrasulfide, 3,3xe2x80x2-bis(di t-butylmethoxysilylpropyl)tetrasulfide, 2,2xe2x80x2-bis(phenyl methyl methoxysilylethyl)trisulfide, 3,3xe2x80x2-bis(diphenyl isopropoxysilylpropyl)tetrasulfide, 3,3xe2x80x2-bis(diphenyl cyclohexoxysilylpropyl)disulfide, 3,3xe2x80x2-bis(dimethyl ethylmercaptosilylpropyl)tetrasulfide, 2,2xe2x80x2-bis(methyl dimethoxysilylethyl)trisulfide, 2,2xe2x80x2-bis(methyl ethoxypropoxysilylethyl)tetrasulfide, 3,3xe2x80x2-bis(diethyl methoxysilylpropyl)tetrasulfide, 3,3xe2x80x2-bis(ethyl di-sec. butoxysilylpropyl)disulfide, 3,3xe2x80x2-bis(propyl diethoxysilylpropyl)disulfide, 3,3xe2x80x2-bis(butyl dimethoxysilylpropyl)trisulfide, 3,3xe2x80x2-bis(phenyl dimethoxysilylpropyl)tetrasulfide, 3-phenyl ethoxybutoxysilyl 3xe2x80x2-trimethoxysilylpropyl tetrasulfide, 4,4xe2x80x2-bis(trimethoxysilylbutyl)tetrasulfide, 6,6xe2x80x2-bis(triethoxysilylhexyl)tetrasulfide, 12,12xe2x80x2-bis(triisopropoxysilyl dodecyl)disulfide, 18,18xe2x80x2-bis(trimethoxysilyloctadecyl)tetrasulfide, 18,18xe2x80x2-bis(tripropoxysilyloctadecenyl)tetrasulfide, 4,4xe2x80x2-bis(trimethoxysilyl-buten-2-yl)tetrasulfide, 4,4xe2x80x2-bis(trimethoxysilylcyclohexylene)tetrasulfide, 5,5xe2x80x2-bis(dimethoxymethylsilylpentyl)trisulfide, 3,3xe2x80x2-bis(trimethoxysilyl-2-methylpropyl)tetrasulfide, 3,3xe2x80x2-bis(dimethoxyphenylsilyl-2-methylpropyl)disulfide.
The preferred sulfur containing organosilicon compounds are the 3,3xe2x80x2-bis(trimethoxy or triethoxy silylpropyl)sulfides. The most preferred compounds are 3,3xe2x80x2-bis(triethoxysilylpropyl)disulfide and 3,3xe2x80x2-bis(triethoxysilylpropyl)tetrasulfide. Therefore as to formula 15, preferably Z is
where R2 is an alkoxy of 2 to 4 carbon atoms, with 2 carbon atoms being particularly preferred; alk is a divalent hydrocarbon of 2 to 4 carbon atoms with 3 carbon atoms being particularly preferred; and n is an integer of from 2 to 5 with 2 and 4 being particularly preferred.
The amount of the sulfur containing organosilicon compound of formula 15 in a rubber composition will vary depending on the level of other additives that are used. Generally speaking, the amount of the compound of formula 15 will range from 0.5 to 20 phr. Preferably, the amount will range from 1 to 10 phr.
It is readily understood by those having skill in the art that the rubber composition would be compounded by methods generally known in the rubber compounding art, such as mixing the various sulfur-vulcanizable constituent rubbers with various commonly used additive materials such as, for example, sulfur donors, curing aids, such as activators and retarders and processing additives, such as oils, resins including tackifying resins and plasticizers, fillers, pigments, fatty acid, zinc oxide, waxes, antioxidants and antiozonants and peptizing agents. As known to those skilled in the art, depending on the intended use of the sulfur vulcanizable and sulfur vulcanized material (rubbers), the additives mentioned above are selected and commonly used in conventional amounts. Representative examples of sulfur donors include elemental sulfur (free sulfur), an amine disulfide, polymeric polysulfide and sulfur olefin adducts. Preferably, the sulfur vulcanizing agent is elemental sulfur. The sulfur vulcanizing agent may be used in an amount ranging from 0.5 to 8 phr, with a range of from 1.5 to 6 phr being preferred. Typical amounts of tackifier resins, if used, comprise about 0.5 to about 10 phr, usually about 1 to about 5 phr. Typical amounts of processing aids comprise about 1 to about 50 phr. Such processing aids can include, for example, aromatic, naphthenic, and/or paraffinic processing oils. Typical amounts of antioxidants comprise about 1 to about 5 phr. Representative antioxidants may be, for example, diphenyl-p-phenylenediamine and others, such as, for example, those disclosed in the Vanderbilt Rubber Handbook (1978), Pages 344 through 346. Typical amounts of antiozonants comprise about 1 to 5 phr. Typical amounts of fatty acids, if used, which can include stearic acid comprise about 0.5 to about 3 phr. Typical amounts of zinc oxide comprise about 2 to about 5 phr. Typical amounts of waxes comprise about 1 to about 5 phr. Often microcrystalline waxes are used. Typical amounts of peptizers comprise about 0.1 to about 1 phr. Typical peptizers may be, for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide.
Accelerators are used to control the time and/or temperature required for vulcanization and to improve the properties of the vulcanizate. In one embodiment, a single accelerator system may be used, i.e., primary accelerator. The primary accelerator(s) may be used in total amounts ranging from about 0.5 to about 4, preferably about 0.8 to about 1.5, phr. In another embodiment, combinations of a primary and a secondary accelerator might be used with the secondary accelerator being used in smaller amounts, such as from about 0.05 to about 3 phr, in order to activate and to improve the properties of the vulcanizate. Combinations of these accelerators might be expected to produce a synergistic effect on the final properties and are somewhat better than those produced by use of either accelerator alone. In addition, delayed action accelerators may be used which are not affected by normal processing temperatures but produce a satisfactory cure at ordinary vulcanization temperatures. Vulcanization retarders might also be used. Suitable types of accelerators that may be used in the present invention are amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates. Preferably, the primary accelerator is a sulfenamide. If a second accelerator is used, the secondary accelerator is preferably a guanidine, dithiocarbamate or thiuram compound.
The mixing of the rubber composition can be accomplished by methods known to those having skill in the rubber mixing art. For example the ingredients are typically mixed in at least two stages, namely at least one non-productive stage followed by a productive mix stage. The final curatives including sulfur vulcanizing agents are typically mixed in the final stage which is conventionally called the xe2x80x9cproductivexe2x80x9d mix stage in which the mixing typically occurs at a temperature, or ultimate temperature, lower than the mix temperature(s) than the preceding non-productive mix stage(s). The rubber and block copolymer are mixed in one or more non-productive mix stages. The terms xe2x80x9cnon-productivexe2x80x9d and xe2x80x9cproductivexe2x80x9d mix stages are well known to those having skill in the rubber mixing art. The block copolymer may be added as a separate ingredient or in the form of a masterbatch. The rubber composition containing the block copolymer, as well as the sulfur-containing organosilicon compound, if used, may be subjected to a thermomechanical mixing step. The thermomechanical mixing step generally comprises a mechanical working in a mixer or extruder for a period of time suitable in order to produce a rubber temperature between 140xc2x0 C. and 190xc2x0 C. The appropriate duration of the thermomechanical working varies as a function of the operating conditions and the volume and nature of the components. For example, the thermomechanical working may be from 1 to 20 minutes.
One feature of the many block copolymers is their solubility in organic solvents. This feature offers the opportunity to incorporate such block copolymers into the first rubber elastomers via a number of ways aside from mechanical working in a mixer or extruder. For example, it is contemplated that one can disperse or dissolve the block copolymer in a polymer cement (elastomer solubilized in an organic solvent) with mixing and removal of the solvent to yield a uniformly dispersed block copolymer in the elastomer. In accordance with another embodiment, one can solubilize the block copolymer in the organic solvent along with the monomer or monomers for subsequent solution polymerization. Under this embodiment, the monomers polymerize to form the elastomer in the block copolymer media.
The rubber composition containing the rubber and block copolymer may be incorporated in a variety of rubber components of the tire. For example, the rubber component may be a tread (including tread cap and tread base), sidewall, apex, chafer, sidewall insert, wirecoat and ply coat. Preferably, the compound is the tread including a tread cap and/or tread base.
The pneumatic tire of the present invention may be a passenger tire, aircraft tire, agricultural, earthmover, off-the-road, truck tire and the like. Preferably, the tire is a passenger or truck tire. The tire may also be a radial or bias, with a radial being preferred.
Vulcanization of the pneumatic tire of the present invention is generally carried out at conventional temperatures ranging from about 100xc2x0 C. to 200xc2x0 C. Preferably, the vulcanization is conducted at temperatures ranging from about 110xc2x0 C. to 180xc2x0 C. Any of the usual vulcanization processes may be used such as heating in a press or mold, heating with superheated steam or hot air.
Upon vulcanization of the sulfur vulcanized composition, the rubber composition of this invention can be used for various purposes. For example, the sulfur vulcanized rubber composition may be in the form of a tire, belt or hose. In case of a tire, it can be used for various tire components. Such tires can be built, shaped, molded and cured by various methods which are known and will be readily apparent to those having skill in such art. Preferably, the rubber composition is used in a sidewall and/or the tread of a tire. As can be appreciated, the tire may be a passenger tire, aircraft tire, truck tire and the like. Preferably, the tire is a passenger tire. The tire may also be a radial or bias, with a radial tire being preferred.

Pneumatic tire having a rubber component containing a block styrene butadiene copolymer


A process for producing granules of anionic surfactant, preferably PAS by in situ neutralisation of a precursor acid to form the surfactant, heating the surfactant to a temperature in excess of 130xc2x0 C. and subsequently cooling the to provide surfactant granules is disclosed. Detergent compositions containing such granules are also disclosed.

The present invention relates to detergent particles, a process for their production and a composition containing them. More particularly the present invention relates to a process for the production of detergent particles having a high level of anionic surfactant which involves in situ neutralisation of an acid precursor of the anionic surfactant and drying of the surfactant thereby produced and to the particles thereby obtained.
Detergent-active compounds conventionally employed in detergent compositions include anionic surfactants e.g. linear alkylbenzene sulphonates (LAS), linear alkyl ether sulphate (LES) and primary alkyl sulphates (PAS), and nonionic surfactants e.g. alcohol ethoxylates. To improve detergency performance it is desirable to provide a high level of detergent-active material in the powder.
Often, the maximum level of active that may be incorporated is limited by process requirements. Detergent compositions having a high bulk density are typically prepared by a process involving mixing or granulation of components of the composition and/or a base powder obtained for example from a spray-drying process and provide significant consumer benefits as compared to compositions of lower bulk density. It is known to incorporate detergent active compounds into such compositions in liquid form. However as it is necessary to control the ratios of liquids to solids in order to form detergent granules the maximum level of detergent active material which may be incorporated in this manner is limited. It is also known to incorporate anionic surfactant e.g. PAS in detergent compositions by means of a solid adjunct, that is, a particle comprising the surfactant and other components of the composition e.g. sodium carbonate and builder. Hitherto, the level of anionic surfactant present in such adjuncts has been limited due to the need to provide good flow properties and reduce the tendency to agglomerate. It is also known to incorporate anionic surfactants by the in-situ neutralisation of an acid precursor of the surfactant.
EP-A-506 184 (Unilever) discloses a process for the continuous dry neutralisation of liquid acid precursor of anionic surfactant. Detergent particles having an active detergent content of 30 to 40% by weight may be prepared by this process.
EP 572 957 discloses a process for producing a powdery anionic surfactant by feeding an aqueous slurry of the surfactant containing 60 to 80% solids into an evaporator, forming a film of the surfactant on the reactor wall and scraping it from the wall whilst drying and concentrating the slurry. The production of particles comprising anionic surfactant by in-situ neutralisation is not disclosed.
However, sufficient water must be present in the slurry to ensure that the slurry be pumpable. A large proportion of this water is necessarily removed in producing the powdery surfactant which requires energy and increases residence time. Thus, the energy required in the process and the throughput of the process are adversely effected where the slurry has a high water content. Moreover, a powder having a high water content may interact unfavourably with water sensitive components in fully formulated detergent compositions, e.g. bleach, thus providing poor stability and storage difficulties.
We have found that by feeding a liquid acid precursor of a anionic surfactant and neutralising agent to a drying zone and forming the anionic surfactant in-situ in the drying zone the above disadvantages may be ameliorated.
Accordingly a first aspect of the invention provides a process for the production of detergent particles comprising at least 50% and preferably 65% by weight of an anionic surfactant and not more than 20% and preferably not more than 15% by weight of water which comprises contacting a pumpable precursor acid of an anionic surfactant with a pumpable aqueous neutralising agent in a drying zone to produce an anionic surfactant the total water content being in excess of 10% by weight and preferably in excess of 20% by weight, heating the surfactant to a temperature in excess of 130xc2x0 C. and preferably in excess of 140xc2x0 C. in the said drying zone to reduce the water content to not more than 20% and preferably not more than 15% by weight, and subsequently cooling the surfactant to form detergent particles.
The heat of neutralisation evolved in the drying zone reduces the requirement for external heating of the drying zone and is advantageous over processes in which surfactant paste is employed as a feedstock.
Moreover, it is a particular advantage of the present invention that the precursor acid may be fed to the drying zone in liquid form rather than as an aqueous solution and the neutralising agent may be concentrated. The total amount of water introduced into the drying zone may be reduced significantly as compared to processes in which a surfactant paste is employed. Such pastes may require at least 30% by weight of water in order to be pumpable.
The present process may be operated as a single step process (ie. the detergent particles are obtained directly from a precursor acid feedstock) rather than as a two step process involving production of the surfactant and subsequent formation and drying of a paste to form the detergent particles. This is advantageous as the need to produce a surfactant paste, which can present technical difficulties, is avoided as is the need for transport and storage of the paste.
The precursor acid for example PAS acid, is suitably fed to the drying zone in the liquid phase. As the precursor acid may be thermally unstable, the neutralisation preferably occurs sufficiently rapidly and substantially completely such that thermal decomposition of the acid due to the elevated temperature is minimised and desirably avoided.
The precursor acid is suitably fed into the drying zone at a temperature of 40xc2x0 to 60xc2x0 C. to ensure it is in the liquid form but without encouraging thermal decomposition. The neutralising agent may be fed into the drying zone at any desired temperature but 50xc2x0 to 70xc2x0 C. is preferred to facilitate neutralisation rather than acid decomposition.
In order to effect removal of water, the walls of the drying zone are suitably at a temperature of at least 100xc2x0 C., preferably at least 130xc2x0 C. and especially at least 140xc2x0 C.
Suitably the neutralising agent is introduced as an aqueous solution or slurry. Conventional neutralising agents may be employed including alkali metal hydroxides for example sodium hydroxide and alkali metal carbonates, for example sodium carbonate.
Suitably the neutralising agent is present in an amount of 25 to 55% and preferably a 30 to 50% by weight of the aqueous solution or slurry. A high concentration of the neutralising agent may give unwanted crystallisation and a low concentration is undesirable due to the large proportion of water.
The concentration of the neutralising agent solution or slurry may be varied in order to control the water content in the drying zone. Thus, optimum viscosity characteristics may be attained whereby the material in the drying zone remains transportable/pumpable.
A stoichiometric excess of neutralising agent with respect to the acid precursor may be employed. The excess neutralising agent combines the acid, for example sulphuric acid which may be produced if part of the precursor acid thermally decomposes.
Desirably the drying zone is under a slight vacuum to facilitate the removal of water and volatiles. The vacuum may be from 100 Torr up to atmospheric pressure as this provides significant process flexibility. However, a vacuum in excess of 500 Torr up to atmospheric has the advantage of reducing capital investment whilst providing vacuum operation.
We have found that improved control of residence time and particle size may be secured, disadvantageous thermal decomposition of the acid may be reduced or avoided and process throughput may be increased by agitating the material in the drying and/or cooling zone.
Accordingly a second aspect of the invention provides a process for the production of detergent particles comprising at least 50% and preferably 65% by weight of an anionic surfactant and not more than 20% and preferably not more than 15% by weight of water which comprises contacting a pumpable precursor acid of an anionic surfactant with a pumpable neutralising agent in a drying zone to produce an anionic surfactant, the total water content being in excess of 10% and preferably in excess of 20% by weight, agitating the precursor and neutralising agent with agitation means which have a tip speed in excess of 15 msxe2x88x921 and preferably in excess of 20 msxe2x88x921 heating the surfactant to a temperature in excess of 130xc2x0 C. and preferably in excess of 140xc2x0 C. in the said drying zone to reduce the water content to not more than 20% by weight and preferably not more than 15% by weight and subsequently cooling the surfactant to form detergent particles.
Advantageously the present invention provides for rapid throughput as compared to a process in which a paste containing a pre-neutralised surfactant is employed.
The process is preferably continuous as this facilitates continuous transportation of the particles. In a continuous process the flow rate is suitably of the order of 10 to 25 kg/m2/hr and preferably 17 to 22 kg/m2/hr e.g. 20 kg/m2/hr.
Suitably the average residence time in the drying zone is less than 5 minutes. A residence time of less than 4 minutes is especially preferred with as low a residence time as possible being most preferred.
Agitation of the precursor and neutralising agent (hereinafter referred to as the feedstocks) in the heating zone generally provides efficient heat transfer and facilitate removal of water. Agitation reduces the contact time between the feedstocks and the wall of the drying zone which, together with efficient heat transfer, reduces the likelihood of xe2x80x98hot spotsxe2x80x99 forming which may lead to thermal decomposition. Moreover, improved drying is secured thus allowing a shorter residence time/increased throughput in the drying zone.
To avoid thermal decomposition, the temperature of the drying zone preferably does not exceed 170xc2x0 C.
The process of the present invention permits the formation of particles having a high bulk density for example in excess of 550 g/cm3.
The material is cooled in a cooling zone which is suitably operated at a temperature not in excess of 50xc2x0 C. and preferably not in excess of 40xc2x0 C. e.g. 30xc2x0 C. Desirably there is agitation within the cooling zone to provide efficient cooling of the material therein. By actively cooling the particles, the possibility of thermal decomposition occurring due to the particles being heated to a high temperature is reduced.
In addition to the precursor acid and neutralising agent feedstocks, pre-neutralised surfactants eg. PAS, LAS and LES may be fed into the drying zone as a separate feedstock and/or as an admixture with the neutralising agent and/or the precursor acid.
The process of the invention may be carried out in any suitable apparatus however it is preferred that a flash reactor is employed. Suitable flash reactors include e.g. the Flash Drier system available from VRV SpA Impianti Industriali. The drying zone may have a heat transfer area of at least 10 m2. The cooling zone desirably has a heat transfer area of at least 5 m2.
Optionally two or more drying zones may be employed before the cooling zone as desired. A single apparatus may be employed to provide the drying zone and cooling zone as desired or alternatively separate apparatus for example a drier and a cooling fluid bed may be employed.
Suitably the drying zone is substantially circular in cross section and is thus defined by a cylindrical wall. Preferably the said wall is heated by means of a heating jacket through which water, steam or oil may be fed. The inside of the said wall is preferably maintained at a temperature of at least 130xc2x0 C. and especially at least 140xc2x0 C. Preferably the drying zone has an evaporation rate of 3 to 25, and especially 5 to 20 kg water per m2 of heat surface per hour.
The cooling zone is preferably defined by a cylindrical wall. Where the process is continuous, the apparatus is suitably arranged such that the drying zone and cooling zone are substantially horizontally aligned to facilitate efficient drying, cooling and transport of the material through the drying and cooling zones in a generally horizontal direction.
Suitably the drying zone and preferably the cooling zone have agitation means therein which agitates and transports the surfactant paste and forming granules through the said zones. The agitation means preferably comprises a series of radially extending paddles and/or blades mounted on an axially mounted rotatable shaft. Desirably the paddles and/or blades are inclined in order to effect transportation and preferably have a clearance from the inner wall of no more than 10 mm, for example 5 mm.
We have found that the present invention has especial applicability in the production of detergent particles comprising PAS. PAS is presently available on the market in fine powder form or in noodle form. The fine powder is generally dusty, having a significant quantity of particles of less than 150 microns. PAS noodles are generally produced by extruding dried PAS which has the appearance of soap chips and typically have a very large particle size and a very low porosity leading to poor dissolution characteristics. To increase the level of detergent active material in a detergent composition it is known to post-dose detergent particles to provide a composition having a high level of active material.
However, PAS in fine powder form and PAS noodles are generally not suitable for post-dosing into a detergent composition as the composition particles and the post-dosed particles are generally of different particle size and thus tend to segregate and be unsightly. The process according to the present invention enables detergent particles having a high level of detergent active material and suitable porosity and particle size characteristics to be obtained.
Accordingly a third aspect of the invention provides detergent particles comprising at least 60% by weight of the particle of an anionic surfactant, preferably PAS, and not more than 15% by weight of the particle of water, the particles being obtainable by a process according to the first or second aspect of the invention.
According to a fourth aspect of the invention there is provided detergent particles comprising an anionic surfactant, preferably PAS in an amount of at least 60% by weight of the particle, wherein the particles have a porosity of 5 to 50% volume of the particle and a particle size distribution such that at least 80% of the particles have a particle size of 180 to 1500 microns, preferably 250 to 1200 microns and less than 10% and preferably less than 5% of the particles have a particle size less than 180 xcexcm.
We have found that the dissolution characteristics of particles comprising PAS may be improved by reducing the Krafft temperature of the PAS active to below 13xc2x0 C., the Krafft temperature for PAS which is conventionally employed in detergent products.
Accordingly, a further aspect of the invention provides detergent particles comprising PAS, preferably at a level of at least 60%, more preferably at least 70% and especially at least 85% by weight of the particle, wherein the PAS has a Krafft temperature below 13xc2x0 C. and the average particle size is from 180 to 1500 xcexcm.
Preferably the particles are produced by a process according to the invention as herein described.
Suitably at lease 50% and especially at least 70% of the PAS has a linear alkyl chain.
Preferably the Krafft temperature is below 10xc2x0 C. and more preferably below 5xc2x0 C. as the solubility of the PAS is significantly superior at temperatures above the Krafft temperature.
The Krafft temperature of the PAS may be reduced by any suitable means.
It has been surprisingly found that by employing a narrow alkyl chain length distribution, the Krafft temperature thereof may be reduced. Preferably at least 90% and preferably at least 95% of the PAS active has a chain length of C12 to C16 and especially, for example EMPICOL LXV100 (tradename) ex Albright and Wilson.
The Krafft temperature may also be reduced by employing a branched detergent active, preferably an alkyl benzene sulphonate, alcohol sulphate, Guerbet alcohol sulphate, secondary alcohol sulphate, secondary alkyl sulphonates, secondary and preferably premixing together with a linear alcohol sulphate. Branched chain surfactants may assist in foam generation which is desirable for the consumer in some markets.
Examples of suitable branched surfactants include PETRELAB 550, LIAL 123 AS (ex DAC).
The Krafft temperature of the PAS may be reduced by employing a quaternary ammonium counterion for up to 50 mole %, preferably up to 30 mole % and especially up to 20 mole % of the detergent active in particles. Preferably the quaternary ammonium counterion is selected from ammonium and quaternised mono, di or tri alkanol amine, for example ethanol amines.
Examples of suitable materials include the TEXAPON (tradename) range of surfactants ex Henkel.
The Krafft temperature may be lowered by employing, a narrow chain length distribution, a branched chain surfactant or a quaternary ammonium counterion, preferably a combination of these factors is employed to achieve further improvement in the solubility of the detergent particles.
Suitably the anionic surfactant in the detergent particles according to the third and fourth aspects of the invention is present in an amount of at least 65% preferably at least 85% and desirably at least 90% by weight of the particles. The particles may also comprise water in an amount of 1 to 20%, preferably 1 to 15% and more preferably 1 to 10% by weight of the particles. The water in the particle provides improved granule integrity thus reducing the level of the fine particles.
Suitably at least 80%, preferably 90% and more preferably 95% of the particles have a mean particle size of 300 to 1000 microns and more preferably 400 to 900 microns.
Desirably the detergent particles have an aspect ratio not in excess of 2 and more preferably are generally spherical in order to reduce segregation from other particles in a formulated detergent composition and to enhance the visual appearance of the powder.
Suitably the PAS surfactant has a chain length of C10 to C22 preferably C12 to C18 and more preferably a narrow range of C12 to C14, Coco PAS is particularly desirable.
The detergent particle may comprise mixtures of PAS with other surfactants and/or non surfactant components as desired.
Suitable other surfactants may comprise alkyl benzene sulphonates, oxo alcohol sulphates for example C11 to C15 and C13 to C15 alcohol sulphates, secondary alcohol sulphates and sulphonates, unsaturated surfactants for example sodium oleate, oleyl sulphates, xcex1-olefin sulphonate, or mixtures thereof.
Especially preferred are PAS rich particles, that is particles in which the amount of PAS exceeds the amount of any other surfactant or non-surfactant and more preferably exceeds the total amount of all other surfactant and non-surfactant components.
Generally the sodium salt of the surfactants will be employed however, mono, di or tri alkanolamine and/or ammonium counterions which provide a structurexe2x80x94weakening effect may be used as desired to improve low temperature solubility of the particles.
Other non-surfactant components which may be present in the detergent particles include dispersion aids, preferably polymeric dispersion aids and more preferably urea, sugars, polyalkyleneoxides; and builders as hereinafter described.
If desired the detergent particles may comprise an organic and/or inorganic salt. Suitable materials in salts, preferably sodium, of tripolyphosphate, citrates, carbonates, sulphates, chlorides.
It is especially preferred that a salt be present in the particle when the anionic surfactant comprises LAS.
The salt may be present at a level of up to 40% and preferably up to 30% by weight of the particles.
The detergent particles may be post-dosed directly to a base powder obtained from any conventional detergent production process including a non tower process in which the components of the detergent composition are mixed and a spray drying process optionally followed by a post tower densification. As the detergent particles produced by the present invention may be post-dosed to such powders a significant degree of formulation flexibility is obtained and the level of active material in the fully formulated composition may be very high as desired. A further advantage is that a base powder which is substantially free of detergent active compounds may be produced as the detergent active compounds may be introduced substantially wholly as post-dosed particles.
Accordingly a fifth aspect of the invention provides a detergent composition comprising detergent particles according the third or fourth aspects of the invention and a base powder.
The option of reducing the level of detergent active material in a base powder is especially advantageous where the base powder is produced by a spray drying process as a lower level of detergent active compound in the spray drying process permits a higher throughput to be secured thus increasing overall production efficiency.
Compositions according to the fifth aspect of the invention generally contain, in addition to the detergent-active compound, a detergency builder and optionally bleaching components and other active ingredients to enhance performance and properties.
Detergent compositions of the invention may contain, in addition to the post-dosed detergent particles, one or more detergent-active compounds (surfactants) which may be chosen from soap and non-soap anionic, cationic, nonionic, amphoteric and zwitterionic detergent-active compounds, and mixtures thereof. Many suitable detergent-active compounds are available and are fully described in the literature, for example, in xe2x80x9cSurface-Active Agents and Detergentsxe2x80x9d, Volumes I and II, by Schwartz, Perry and Berch. The preferred detergent-active compounds that can be used are soaps and synthetic non-soap anionic and nonionic compounds.
Anionic surfactants are well-known to those skilled in the art. Examples include alkylbenzene sulphonates, particularly linear alkylbenzene sulphonates having an alkyl chain length of C8-C15; primary and secondary alkyl sulphates, particularly C12-C15 primary alkyl sulphates; alkyl ether sulphates; olefin sulphonates; alkyl xylene sulphonates; dialkyl sulphosuccinates; and fatty acid ester sulphonates. Sodium salts are generally preferred.
Nonionic surfactants that may be used include the primary and secondary alcohol ethoxylates, especially the C8-C20 aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol, and more especially the C10-C15 primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol. Non-ethoxylated nonionic surfactants include alkylpolyglycosides, glycerol monoethers, and polyhydroxyamides (glucamide).
The total amount of surfactant present in the detergent composition is suitably from 5 to 40 wt % although amounts outside this range may be employed as desired.
The detergent compositions of the invention generally also contain a detergency builder. The total amount of detergency builder in the compositions is suitably from 10 to 80 wt %, preferably from 15 to 60 wt %. The builder may be present in an adjunct with other components or, if desired, separate builder particles containing one or more builder materials may be employed.
Inorganic builders that may be present include sodium carbonate, if desired in combination with a crystallisation. seed for calcium carbonate, as disclosed in GB 1 437 950 (Unilever); crystalline and amorphous aluminosilicates, for example, zeolites as disclosed in GB 1 473 201 (Henkel), amorphous aluminosilicates as disclosed in GB 1 473 202 (Henkel) and mixed crystalline/amorphous aluminosilicates as disclosed in GB 1 470 250 (Procter and Gamble); and layered silicates as disclosed in EP 164 514B (Hoechst). Inorganic phosphate builders, for example, sodium orthophosphate, pyrophosphate and tripolyphosphate, may also be present, but on environmental grounds those are no longer preferred.
Zeolite builders may suitably be present in an amount of from 10 to 60 wt % and preferably an amount of from 15 to 50 wt %. The zeolite used in most commercial particulate detergent compositions is zeolite A. Advantageously, however, maximum aluminium zeolite P (zeolite MAP) described and claimed in EP 384 070A (Unilever) may be used. Zeolite MAP is an alkali metal aluminosilicate of the P type having a silicon to aluminium ratio not exceeding 1.33, preferably not exceeding 1.15, and more preferably not exceeding 1.07.
Organic builders that may be present include polycarboxylate polymers such as polyacrylates, acrylic/maleic copolymers, and acrylic phosphinates; monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono-, di- and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxymalonates, dipicolinates, hydroxyethyliminodiacetates, alkyl- and alkenylmalonates and succinates; and sulphonated fatty acid salts. A copolymer of maleic acid, acrylic acid and vinyl acetate is especially preferred as it is biodegradable and thus environmentally desirable. This list is not intended to be exhaustive.
Especially preferred organic builders are citrates, suitably used in amounts of from 5 to 30 wt %, preferably from 10 to 25 wt %; and acrylic polymers, more especially acrylic/maleic copolymers, suitably used in amounts of from 0.5 to 15 wt %, preferably from 1 to 10 wt %. The builder is preferably present in alkali metal salt, especially sodium salt, form.
Suitably the builder system comprises a crystalline layered silicate, for example, SKS-6 ex Hoechst, a zeolite, for example, zeolite A and optionally an alkali metal citrate.
Detergent compositions according to the invention may also contain a bleach system, desirably a peroxy bleach compound, for example, an inorganic persalt or organic peroxyacid, capable of yielding hydrogen peroxide in aqueous solution. The peroxy bleach compound may be used in conjunction with a bleach activator (bleach precursor) to improve bleaching action at low wash temperatures. An especially preferred bleach system comprises a peroxy bleach compound (preferably sodium percarbonate optionally together with a bleach activator), and a transition metal bleach catalyst as described and claimed in EP 458 397A, EP 458 398A and EP 509 787A (Unilever).
The compositions of the invention may contain alkali metal, preferably sodium, carbonate, in order to increase detergency and ease processing. Sodium carbonate may suitably be present in an amount from 1 to 60 wt %, preferably from 2 to 40 wt %. However, compositions containing little or no sodium carbonate are also within the scope of the invention.
Powder flow may be improved by the incorporation of a small amount of a powder structurant, for example, a fatty acid (or fatty acid soap), a sugar, an acrylate or acrylate/maleate polymer, or sodium silicate which is suitably present in an amount of from 1 to 5 wt %.
Other materials that may be present in detergent compositions of the invention include sodium silicate; antiredeposition agents such as cellulosic polymers; fluorescers; inorganic salts such as sodium sulphate; lather control agents or lather boosters as appropriate; proteolytic and lipolytic enzymes; dyes; coloured speckles; perfumes; foam controllers; and fabric softening compounds. This list is not intended to be exhaustive.
The base composition is suitably prepared by spraying drying a slurry of compatible heat-insensitive ingredients, and then spraying on, admixing and/or postdosing those ingredients unsuitable for processing via. the slurry. The detergent particles produced according to the process of the present invention are post-dosed to the base composition by conventional methods.
Detergent compositions of the invention preferably have a bulk density of at least 500 g/l, more preferably at least 550 g/liter, more preferably at least 700 g/liter.
Such powders may be prepared either by spray-drying, by post-tower densification of spray-dried powder, or by wholly non-tower methods such as dry mixing and granulation. A high-speed mixer/granulator may advantageously be used for such mixing. Processes using high-speed mixer/granulators are disclosed, for example, in EP 340 013A, EP 367 339A, EP 390 251A and EP 420 317A (Unilever).
The invention is illustrated by the following non-limiting Examples.

Production of anionic surfactant granules by in situ neutralization

Lever Brothers Company, division of Conopco, Inc.