A process is disclosed for manufacturing a lubricant composition comprising combining a superabsorbent polymer with a material for decreasing friction between moving surfaces. The superabsorbent polymer absorbs from about 25 to greater than 100 times its weight in water and may comprise a polymer of acrylic acid, an acrylic ester, acrylonitrile or acrylamide, including co-polymers thereof or starch graft co-polymers thereof or mixtures thereof. A product produced by the process includes the material for decreasing friction comprising a petroleum lubricant containing an additive, water containing an additive, synthetic lubricant, grease, solid lubricant or metal working lubricant, wherein the synthetic lubricant, grease, solid lubricant or metal working lubricant optionally contain an additive. A process comprising controlling the delivery of a lubricant to at least one of two moving surfaces in order to decrease friction between said moving surfaces, is also disclosed. This process includes applying the lubricant composition to at least one of the surfaces. The lubricant composition in this instance comprises a superabsorbent polymer combined with a material for decreasing friction between moving surfaces, wherein the material for decreasing friction comprises a petroleum lubricant, water, synthetic lubricant, grease, solid lubricant or metal working lubricant, and optionally an additive.

The field of the invention is lubricants and especially lubricant compositions comprising a superabsorbent polymer in combination with a lubricant material.
Lubricant materials function by separating moving surfaces to minimize friction and wear. Archeological evidence dating to before 1400 B.C. shows the use of tallow to lubricate chariot wheel axles. Leonardo da Vinci discovered the fundamental principles of lubrication and friction, but lubrication did not develop into a refined science until the late 1880""s in Britain when Tower produced his studies on railroad car journal bearings in 1885. In 1886 Reynolds developed this into a theoretical basis for fluid film lubrication.
Lubrication principles vary from the separation of moving surfaces by a fluid lubricant through boundary lubrication, to dry sliding. In many respects, these principals are coextensive.
In fluid film lubrication, the load on moving surfaces is supported entirely by the fluid between the surfaces which is a film under pressure. The pressure on the film develops through the motion of the surfaces, which in turn delivers the lubricant into a converging wedge-shaped zone. The behavior of the moving surfaces is totally dependent on the fluidity or viscous behavior of the lubricant. Film pressure and power loss are dependent on the viscosity of the lubricant as well as the configuration of the moving surfaces, and lubricant shear strength. Hydrodynamic or squeeze-film action cannot provide adequate load support in some instances for bearings lubricated with oil or water. Pumping the lubricant into the moving surfaces sometimes provides the necessary hydrodynamic or squeeze-film properties for bearings used for handling heavy loads in low speed equipment. This practice is especially common with low viscosity lubricants such as water. It would therefore be advantageous to provide additives to these types of lubricants to overcome these difficulties.
Oil film lubricants on surfaces are limited in their lubricating capabilities and as such have load limits. Asperities or high spots-on the moving surfaces will in turn support the load when the load limit of the lubricant is reached so that the lubrication moves from full-film to mixed-film to complete boundary lubrication with an increase in coefficient of friction between the moving surfaces. High load, low speed, low viscosity lubricants, misalignment, high surface roughness or an inadequate supply of lubricant causes this change from full-film to boundary lubrication. Chemical additives, however, can reduce resultant wear and friction.
Surface contact through asperities on the moving surfaces can result in tearing of the surfaces and is especially a problem with increasing loads. Plastic deformation, temperature buildup and welding of the surfaces with eventual seizure of the surfaces occurs as a result. This problem is especially prevalent in hypoid gears used in automobile differentials. Extreme pressure lubricants combat welding of the surfaces in these circumstances and contain organic compounds that react at these elevated temperatures and form high-melting inorganic lubricant films on the surfaces. Sulfur, chlorine, phosphorous and lead compounds in these additives provide low shear strength layers that minimize surface tearing, or coat the moving surfaces to prevent- fusing. Since extreme pressure additives function by chemical action, they are not used where the metal surfaces will be severely eroded. Increasing the lubricant or oil viscosity by means of an additive, lowering the unit bearing loading, improving the finish on the moving surfaces and use of external pressurization offer alternatives to extreme-pressure additives.
Dry rubbing or dry sliding involving solid-to-solid contact occurs in fluid lubrication systems as for example in machine start-up, run-in misalignment or inadequate clearance, reversal of direction of moving surfaces, or any unforeseen or unplanned interruptions in lubricant delivery. Conventional lubricants such as greases or oils also are not used on moving surfaces in extreme temperature, high vacuum, radiation or contamination environments. Dry lubricants applied as thin coatings or as particulate materials in these environments reduce wear and friction of moving surfaces. These films or particulate materials may comprise or incorporate solid or particulate carbon-graphite, lead babbitt, bronze, aluminum, polyethylene or polytetrafluoroethylene solid or particulate materials in a binder where the film or particulates are adhered to one or both of the moving surfaces. The effectiveness of the dry lubricant film or particulates is controlled to some degree by the binder where solid or particulate lubricants are employed as well as conditions of use such as the load, surface temperatures generated during use, speed of the moving surfaces, hardening, fatigue, welding, recrystallization, oxidation and hydrolysis. It would be an advantage therefore to have a binder that is strongly adherent and resistant to some of the conditions generated while in use.
In elastohydrodynamic lubrication carrying the load on rolling contacts in ball and roller bearings, gear teeth, cams or friction drives, minimizes lubrication problems. Focusing the load on a small contact area on these moving surfaces results in high elastic contact stresses. Lubricant films help support the load which is described as xe2x80x9celastohydrodynamic,xe2x80x9d because of the close relationship between the formation of a thin hydrodynamic fluid lubricant film and elastic deformation.
The lubricant viscosity and film conditions at the entry of the contact zone in these systems generally fix the lubricant film thickness which is substantially uniform over most of its length along the contact. It is believed that high contact pressures lead to excessive lubricant viscosity and pressure distribution close to the Hertz pattern for simple static elastic contact theory. It has also been noted that only a slight reduction in film thickness results with increasing loads with pronounced contact deformation. In plotting contact pressure in psi (pounds per square inch) against distance and direction of lubricant flow, it appears that optimum lubricity is obtained with a sharp pressure spike at the exit portion of the lubricant film; however, this does not take into account changes in temperature, relaxation time or other variables in the lubricating system. It would therefore be an advantage to provide an additive that would enhance viscosity and film formation and retention under these and other conditions.
Load capacity with a full elastohydrodynamic film is limited by fatigue strength of the moving surfaces in rolling contact systems. The working of grain boundaries beneath the contact surface, where shear stress is at a maximum, generates damage. Fatigue cracks occur within this heavily stressed zone with repeated stress cycles. Particles are loosened, which is characterized as surface flaking, and represents the depth of the zone of maximum shear stress. The fatigue cracks are started by focal points of oxide particles and stringers of impurities.
Where the lubricant film thickness becomes less than the surface finish of the moving or rolling surfaces, under high load, low speed or low lubricant viscosity, boundary lubrication comes into play which is dependent upon the chemical nature of the lubricant. The drop in fatigue life can be avoided under such conditions as well as surface wear with the proper lubricant additives.
Petroleum based lubricants are extensively used because of their wide availability and consequent low cost. Petroleum lubricants are well known in the art and generally comprise low viscosity and low density paraffins having relatively high freezing points. When combined with oxidation inhibitors to obtain high temperature stability, oxidation resistance is improved and sludging tendency is minimized.
Aromatic petroleum lubricants such as napthenes are generally oxidation stable but form insoluble sludges at high temperatures. Naphthenic oils have low pour point, low oxidation stability and properties between paraffins and aromatics. They are also present in paraffin lubricants to a small degree. Naphthenic oils, however, or naphthenes are used by themselves in combination with oxidation inhibitors. It therefore would be advantageous to provide additives that minimize these difficulties.
Representative petroleum lubricating oils include SAE types 10W, 20W, 30, 40, 50, 10W-30, 20W-40, 75, 80, 90 140, 250 and so-called automatic transmission fluids.
Various additives mixed with lubricating materials help meet the requirements of modern automobile engines, high-speed machinery, high-pressure hydraulic systems, torque converters, aircraft engines, turbine engines, steam engines, steam turbines, electric motors, hydraulic systems and the like.
Petroleum lubricants and other so-called oil-type lubricants employ sulfur, nitrogen or phosphorous type organic compounds, and alkylphenols as antioxidants or oxidation inhibitors. Hydroperoxides initially formed in the oil during oxidation lead to the subsequent production of organic acids and other oxygen containing organic compounds. Antioxidants either inhibit the formation of, or complex, hydroperoxides to minimize the formation of acids, sludge and varnish.
Some commonly employed oxidation inhibitors for steam turbines, electric motors and hydraulic systems include 2-naphthol, di-t-butyl-p-cresol and phenyl-1-naphthylamine. Thiophosphates such as zinc, barium, and calcium thiophosphate are also widely used as antioxidants in lubricating oils for automobile and truck engines.
Alkylsuccinic type acids and other mildly polar organic acids or organic amines are employed as rust inhibitors as well as organic phosphates, polyhydric alcohols, sodium sulfonates and calcium sulfonates.
Many antiwear compounds, generally well known in the art, improve boundary film lubrication, and are classified into seven main groups. The first comprises compounds containing oxygen, such as fatty acids, esters and ketones; the second comprises compounds containing sulfur or combinations of sulfur and oxygen; the third comprises organic chlorine compounds such as chlorinated wax; the fourth includes organic sulfur compounds such as sulphurized fats and sulphurized olefins; the fifth comprises compounds containing both chlorine and sulfur; the sixth, compounds containing organic phosphorous compounds such as tricresyl phosphate, thiophosphates, and phosphites; and the seventh, organic lead compounds such as tetraethyl lead. The use of olefins for lubricating aluminum moving surfaces and iodine for high temperature alloys has also been described in the art.
Antiwear agents employed in boundary lubricants include mildly polar organic acids such as alkylsuccinic type acids and organic amines. Tritresyl phosphate or zinc dialkyldithiophosphate additives are employed in lubricants for hydraulic pumps, gears and torque converters whereas severe rubbing conditions encountered in high load metal-to-metal moving surfaces require lubricants and especially oil type lubricants containing active sulfur, chlorine and lead compounds. These extreme-pressure additives enter into a chemical reaction to form compounds on the surface of the metal moving parts such as lead sulfide, iron chloride or iron sulfide.
Detergents and dispersants are employed in lubricants and function by adsorption on any insoluble particles formed by the moving or sliding contact of two or more surfaces, and maintain the particles in suspension in the lubricant. This minimizes deposits on the moving surfaces and enhances the cleanliness of the moving surfaces. Detergents such as alkyl methacrylate polymers having polar nitrogen groups in the side chain are generally employed and are well known in the art.
The addition of pour-point depressants such as polymethacrylates or wax with naphthalene or wax phenol condensation products also improves the properties of lubricants.
Many lubricants also contain viscosity-index improvers such as polyisobutylenes, polymethacrylates and poly(alkylstyrenes) having a molecular weight of from about 5000 to 20,000. The addition of foam inhibitors such as methyl silicone polymers in lubricating fluids and especially oil type lubricants reduces frothing.
Another class of lubricants comprises synthetic oils such as low molecular weight polymerized olefins, ester lubricants, polyglycols and silicones, all of which are widely known in the art. Other synthetic oils include tricresyl phosphate, silicones, other organic phosphates, polyisobutylene, polyphenyl ethers, silicates, chlorinated aromatics, and fluorocarbons.
The silicone lubricants generally comprise low molecular weight polymers or di-organo substituted silicon oxide where the organo groups are ethyl groups, phenyl groups or mixtures thereof and are formulated either as room temperature liquids having the viscosity of oil or compounded into greases. The chlorophenyl methyl silicone oils are especially suitable.
Organic esters generally comprise diesters based on the condensation of long chain diacids having from about 6 to about 10 carbon atoms such as adipic, azelaic or sebacic acid with branched-chain alcohols having from about 8 to about 9carbon atoms. Higher temperature lubricants employed for turbines and especially jet engines comprise esters of trimethylolpropane or pentaerytheritol with these acids. Polymethacrylates thickening agents, sometimes added in amounts up to about 5%, increase the viscosity of these fluids, which is somewhat lower than petroleum oils.
The polyglycol lubricants comprise those based on polypropylene glycol prepared from propylene oxide and contain terminal hydroxyl groups. These are water insoluble lubricants. Mixtures of prbpylene and ethylene oxides in the polymerization process will produce a water soluble polymer, also used as a lubricant. Liquid or oil type polyglycols have lower viscosities and molecular weights of about 400, whereas 3,000 molecular weight polyglycols are viscous polymers at room temperature. The use of mono- or polyhydric, such as dihydric, alcohols in the ethylene oxide and/or propylene oxide polymerization results in the formation of mono- or diethers which yield a different class of polyglycols. Esterifying the hydroxyl groups in the polyols with low or high molecular weight acids, i.e., those having up to about 18 carbon atoms gives another variety of polyglycol lubricants.
The polyglycols are employed in various industrial hydraulic fluid applications. They generally do not dissolve rubber and find use as rubber lubricants or as textile fiber lubricants in textile processing. Because they decompose into volatile products at high temperatures they also find use in once-through lubrication systems such as in jet aircraft engines and other high temperature operations that would result in depositing carbonaceous materials on the moving surfaces and consequent operational and maintenance difficulties. Combining water soluble polyglycols with water provides compositions for use in hydraulic applications such as die casting machines, furnace controls, electric welders, and navy hydraulic catapults, as well as equipment handling for missiles.
The phosphate lubricants find use in fire resistance applications and generally comprise triaryl or trialkyl phosphates. Fire resistance applications include die casting machines, aircraft hydraulic fluids, air compressor lubricants and various naval and industrial systems. Blending the phosphates with chlorinated biphenyls provides hydraulic stability.
Polymerization of isobutylene containing smaller amounts of 1-butene and 2-butene provides polybutylene lubricants ranging in viscosity from 5 to over 600 centistokes at 210xc2x0 F. with a chain length of from about 20 to greater than about 100 carbon atoms. Polyisobutylenes find application in high temperature apparatus such as conveyors, ovens, dryers and furnaces since they decompose and oxidize substantially to entirely volatile by-products leaving no carbon residue contrary to petroleum based lubricants. They find use in electrical transformers, cables, and refrigerator compressors with the higher viscosity grades employed as viscosity-index additives in petroleum lubricants.
Polyphenyl ethers or polyphenoxy polymers, with the ether group in the three phenyl -position in the polymer chain find use in high temperature applications such as jet engines and hydraulic systems since they exhibit temperature stability at about 500xc2x0 F.
Silicate ester high temperature hydraulic fluids generally comprise tetra(2-ethylhexyl) and tetra(2-ethylbutyl) silicates as well as the so-called dimer silicates such as hexa(2-ethylbutoxy) disiloxane.
Chlorinated bi-phenyl fluids provide fire resistance for lubricating fluids and hydraulic fluids.
Fluorocarbons such as polychlorotrifluoroethylene and copolymers of perfluoroethylene perfluoropropylene non-solid lubricants provide high oxidation resistance in lubricating liquid oxygen and hydrogen peroxide manufacturing and handling equipment.
Greases comprise high viscosity lubricating fluids, made by combining a petroleum or synthetic lubricating fluid with a thickening agent. The thickeners generally comprise fatty-acid soaps of lithium, calcium, strontium, sodium, aluminum, silica gel, and barium. The grease formulation may also include coated clays such as bentonite and hectorite clays coated with quaternary ammonium compounds. Sometimes carbon black is added as a thickener to improve high-temperature properties of petroleum and synthetic lubricant greases. The addition of organic pigments and powders which include arylurea compounds indanthrene, ureides, and phthalocyanines provide high temperature stability.
Grease additives generally fall into the same category as the additives employed in petroleum lubricants including amine, phenolic, phosphite, sulfur, and selenium oxidation inhibitors. Amine deactivators are also employed where copper staining would be a problem or where copper would tend to promote catalytic oxidation. Amine salts, metal sulfonates, metal naphthenates, esters, and nonionic surfactants provide added water resistance, and some protection against salt-spray corrosion.
Greases employed in gear applications or sliding surface applications contain extreme-pressure additives such as lead soaps, sulfur, chlorine and phosphorous additives as described above. Adding solid powders such as graphite, molybdenum disulfide, asbestos, talc, and zinc oxide provides boundary lubrication.
Glycerol stabilizes the soap structure when used in combination with small amounts of water as well as dimethylsilicone oil to minimize foaming.
Formulating the foregoing synthetic lubricants with thickners provides specialty greases and include, without limitation, polyglycol, diester, silicone-diester, polyester, and silicone lubricants. Nonmelting thickeners are especially preferred such as copper phthalocyanine, arylureas, indanthrene, and organic surfactant coated clays. The organic esters and the silicone greases are generally employed in military applications especially for high temperature use.
The mechanical properties of greases have been measured and those materials having a NLGI number from 0 to 6 characterize these greases.
Solid lubricants include inorganic compounds, organic compounds, and metal in the form of films or particulate materials to provide barrier-layer type of lubrication for sliding surfaces. These materials are substantially solid at room temperature and above, but in some instances will be substantially liquidus above room temperature.
The inorganic compounds include materials such as cobalt chloride, molybdenum disulfide, graphite, tungsten disulfide, mica, boron nitride, silver sulfate, cadmium chloride, cadmium iodide, borax and lead iodide. These compounds exemplify the so-called layer-lattice solids in which strong covalent or ionic forces form bonds between atoms in an individual layer while weaker Van der Waal""s forces form bonds between the layers. They generally find use in high temperature applications because of their high melting points, high thermal stabilities in vacuum, low evaporation rates, and good radiation resistance. Especially suitable materials include formulated graphite and molybdenum disulfide. Both molybdenum disulfide and graphite have layer-lattice structures with strong bonding within the lattice and weak bonding between the layers. Sulfur-molybdenum-sulfur lattices form strong bonds whereas weak sulfur-sulfur bonds between the layers allow easy sliding of the layers over one another. Molybdenum disulfide and graphite are therefore especially important solid inorganic lubricants.
The particulate solid materials are formulated as colloidal dispersions in either water, wax, wax emulsions, petroleum oil, castor oil, mineral spirits. The solid non-particulate materials may be employed as solutions in solvents selected to dissolve the solids to form a substantially liquidus composition at room temperature. These solutions in turn can be made into emulsions as described herein, especially water emulsions. Where solvents are unavailable or difficult or expensive to use, the solid lubricants are used as particulates.
The emulsions, as that term is used herein, are either water in oil or oil in water emulsions, or oil in oil emulsions where the solution is either the continuous or discontinuous phase. Water dispersions are used for lubricating dies, tools, metal-working molds, oxygen equipment and in wire drawing.
Graphite-water dispersion used as a lubricant lose water due to evaporation, which is a disadvantage. Mixing the graphite with cadmium oxide or molybdenum disulfide overcomes this.
Other suitable inorganic materials that do not have the layer-lattice structure include basic white lead or lead carbonate, zinc oxide, and lead monoxide.
Dispersing the inorganic compounds in various liquids such as lower molecular weight alcohols, glycols, petroleum oils, synthetic oils, and water, provides compositions used in airframe lubrication, fastenings such as nuts and bolts or screws, gears, wire drawing, and lubricating fittings.
Solid organic lubricant compounds comprise high melting organic powders such as phenanthrene, copper phthalocyanine, and mixtures with inorganic compounds and/or other lubricants. Copper phthalocyanine admixed with molybdenum disulfide comprises a good roller bearing lubricant.
The metal lubricants generally comprise soft metals such as gallium, indium, thallium, lead, tin, gold, silver, copper and the Group VIII noble metals, ruthenium, rhodium, palladium, osmium, iridium, and platinum. Forming these metal lubricants into particulate dispersions in a fluid and especially a liquid such as a liquid lubricant as described herein including petroleum oils, synthetic oils, and water provides easily applied lubricant compositions. Chalcogenides of the non-noble metals may also be employed, especially the oxides, selenides, or sulfides.
Combining the solid lubricants with various binders keeps them in place on the moving surface. Binders are especially necessary in dry lubricant applications employing solid or particulate lubricants, and are sometimes described as bonded solid lubricants. Various thermosetting and thermoplastic and curable binder systems include phenolic, vinyl, acrylic, alkyd, polyurethane, silicone, and epoxy resins. It would be an advantage, however, to provide a novel binder that performed in the same way or improved on the function of these binders.
These types of coatings find application as lubricants for fasteners and bolt assemblies. The solid lubricants employed in the latter application usually include silver, nickel, copper, molybdenum disulfide, lead, or graphite.
Metal working is another important area of lubrication metal working which generally comprises operations involving machining, grinding, honing, lapping, stamping, blanking, drawing, spinning, extruding, molding, forging, and rolling. The lubricants employed generally comprise water, mineral oils, fatty oils, and fatty acids, waxes, soaps, various chemical compounds, minerals, and synthetic lubricants as described herein. Some of the foregoing materials will be at a disadvantage because they do not have the proper sticking properties or viscosity properties to remain in place on the metal surfaces during working and accordingly have to be formulated to assure that they will be in place during the metal working operation. The addition of synthetic polymers to these lubricants would overcome some of these disadvantages.
Lubricants are also described by Kirk-Othmer Encyclopedia of Chemical Technology, Second Edition, pp. 559-595 which is incorporated herein by reference.
For the purpose of the present invention, all of the foregoing lubricant compounds or composition will be referred to as materials for decreasing friction between moving surfaces or lubricants.
From the foregoing, it should be apparent that there is a need for additional materials that will provide the same advantages as those of the related art as well as additional advantages and also materials that will overcome some of the various disadvantages of the related art.
Accordingly, the present invention is directed to a novel composition which includes a material for decreasing friction between moving surfaces as well as a method for lubricating a surface.
These and other advantages are obtained according to the present invention, which is the provision of a composition and a process to enhance the various advantages of the related art and which also substantially obviate one or more of the limitations and disadvantages of the described prior compositions of matter and processes.
The description which follows sets forth additional features and advantages of the invention, apparent not only from the description, but also by practicing the invention. The written description and claims hereof particularly point out the objectives and other advantages of the invention and show how they may be realized and obtained.
To achieve these and other advantages, and in accordance with the purpose of the invention, as embodied and broadly described, the invention comprises a lubricant composition of matter comprising a superabsorbent polymer combined with a material for decreasing friction between moving surfaces or a lubricant as described herein. Where the lubricant is water or a petroleum oil, the composition also includes an additive such as described herein including without limitation, an oxidation inhibitor, a rust inhibitor, antiwear agent, detergent-dispersant, pour-point depressant, viscosity-index improver or foam inhibitor, especially those described herein.
The invention also comprises a method of lubricating a surface comprising coating the surface with a lubricating composition comprising a superabsorbent polymer combined with a material for decreasing friction between moving surfaces as described herein; however, the method of the invention includes the use of water or oil as lubricants as well as other lubricants either with or without additives as described herein. In a further embodiment, the invention relates to the controlled delivery of a lubricant to a surface in order to decrease friction between moving surfaces, by applying the lubricant composition of the invention to at least one of such surfaces.
The invention also comprises a process for manufacturing the aforesaid lubricant composition for decreasing friction between moving surfaces: by combining a lubricant with a superabsorbent polymer. In those instances where the various components of the lubricant composition react with one another and their identity in the final composition is difficult or impossible to partially or completely ascertain, a product is produced according to the invention which is made by the inventive process. The invention, therefore, also relates to a novel product produced by the process of the invention.
The invention also relates to a process comprising controlling the delivery of a lubricant to at least one of two moving surfaces in order to decrease friction between said moving surfaces, comprising applying a lubricant composition or product produced according to the process of the invention to at least one of said surfaces. It is intended that applying the lubricant composition or the product produced according to the invention to at least one of the surfaces is to include those instances where one, some, or all of the surfaces are stationary, or one, some, or all of the surfaces are moving, but in any event, such surfaces are or will be frictionally engaged with one another.
Applicant intends that controlling the delivery of the lubricant to a surface includes phenomena where the lubricant is incrementally withdrawn, incrementally, released, incrementally, delivered or incrementally applied from the lubricant composition of matter or the product produced by the process of the invention. In another embodiment, controlling delivery can be effected by one of the surfaces skimming a microscopic layer, and in some instances one or more molecular layers of the lubricant composition or product produced by the process of the invention from at least one other surface and leaving the remainder of the composition or product on at least one other surface.
In another aspect of the invention, the various lubricants can act as plasticizers for the superabsorbent polymer, especially the organic lubricants and particularly those organic lubricants that are liquids at about 15 to about 30xc2x0 C. Where the lubricants comprise the so-called MORFLEX(copyright), CITROFLEX(copyright), and AROSURF(copyright) compounds, as those compounds are defined herein, they especially include various lubricant additives as defined herein.
Throughout the written description and claims, the lubricant composition is described as a superabsorbent polymer combined with a material for decreasing friction between moving surfaces or lubricant, by which it is intended that the superabsorbent polymer and the lubricant either form a solution, a dispersion, or an emulsion including both water in oil emulsions as well as oil in water emulsions, and oil in oil emulsions wherein a solution is emulsified, and where the solution can be the continuous phase or the discontinuous phase.
The superabsorbent polymer employed according to the invention, absorbs from about 25 to greater than 100 times its weight in water and comprises a polymer of acrylic acid, an acrylic ester, acrylonitrile or acryladmide, including copolymers thereof or starch graft copolymers thereof, or mixtures thereof, where the mixtures contain from 2 to about 3 or 4 superabsorbent polymers.
Superabsorbent polymers that may be employed in the present invention comprise those generally described and those specifically set forth by Levy in U.S. Pat. Nos. 4,983,389, 4,985,251, and particularly those described in U.S. Pat. No. 4,983,389, in column 9, lines 37-48, column 10, lines 40-68, and column 11, lines 1-21 as well as those also described in U.S. Pat. No. 4,985,251, column 9, lines 1-30. The various U.S. patents to Levy, are incorporated herein by reference for their teachings relative to the superabsorbent polymers.
Other superabsorbent polymers include AQUASORB(copyright) which are copolymers of acrylamide and sodium acrylate or the potassium or ammonium salts thereof; AQUASORB(copyright) which are acrylamide-sodium polyacrylate cross-linked copolymers; AQUASTORE(copyright) which is an ionic polyacrylamide, and cross-linked modifiied polyacrylamides, TERRA-SORB(trademark) which is a hydrolyzed starch-polyacrylonitrile; SANWET(copyright) which is a starch-graft-sodium-polyacrylate, or a polyurethane with starch-graft-sodium polyacrylate, starch-graft-sodium polyacrylate, starch, polyer with 2-propenoic acid, sodium salt, WATER LOCK(copyright) which is a poly-2-propenoic acid, sodium salt, and a starch-g poly (2-propenamide-co-2-propenoic acid, sodium salt) or mixed sodium and aluminum salts or potassium or a 2-propenoic acid, sodium salt or polyacrylamide-co-sodium acrylate); AQUAKEEP(copyright) which is a polyacrylic acid, sodium salt, AGRI-GEL(copyright) which is an acrylonitrile starch graft copolymer, SGP(copyright) 502S which is a starch-g-poly (acrylamide-co-sodium acrylate; STOCKOSORB(copyright) which comprise acrylate/acrylamide copolymers, acrylate/polyvinyl alcohol copolymers, and polyacrylates, and the various sodium and potassium salts thereof, FAVORP(copyright) C which is a potassium polyacrylate/polyacrylamide copolymer; XU 40346.00 from Dow Chemical which is a partial sodium slat of cross-linked polypropenoic acid; ASAP(trademark) 1000 which is a reaction product of lightly cross-linked sodium polyacrylate in water with hydrophobic amorphous silicon dioxide, and acrylic acid, ARIDALL(copyright) which are sodium or potassium polyacrylates that may be lightly cross-linked, SANWET(copyright) which is a starch grafted sodium polyacrylate, NORSOCRYL(copyright) which is a poly(sodium acrylate) homopolymer, and ALCOSORB(trademark) which is a copolymer of acrylamide and sodium acrylate, and the various superabsorbent polymers described by Takeda et al. U.S. Pat. No. 4,525,527; Mikita et al. U.S. Pat. No. 4,552,938; U.S. Pat. No. 4,618,631; Mikita et al. U.S. Pat. No. 4,654,393; Alexander et al. U.S. Pat. No. 4,677,174; Takeda et al. U.S. Pat. No. 4,612,250; Mikita et al. U.S. Pat. No. 4,703,067; and Brannon-Peppas, Absorbent Polymer Technoloy, 1990. Other superabsorbent polymers may be employed which are further described by Buchholz et al., Superabsorbent Polymers. Science and Technology, 1994 ACS. All of the foregoing are incorporated herein by reference.
The invention also includes the addition of other materials to the superabsorbent polymer to enhance its loading characteristics, and includes hygroscopic materials such as acrylic acid copolymers (e.g., PEMULEN(copyright)TR-1), and the various inorganic or organic art known equivalents thereof, especially the organic hygroscopic materials. Other organic hygroscopic materials in this respect include glycerol, and the various soaps, especially those described herein, and may also be employed, as well as mixtures of hygroscopic materials, especially the 2 to about 3, or about 4 component mixtures.
Mixtures of these hygroscopic materials with the superabsorbent polymers may also be employed, especially the 2 to about 3, or about 4 component mixtures.
In one embodiment, the material for decreasing friction comprises a petroleum lubricant containing an additive, water containing an additive, synthetic lubricant, grease, solid lubricant or metal working lubricant, wherein said synthetic lubricant, grease, solid lubricant or metal working lubricant optionally contain an additive. Lubricating oils include either a petroleum oil or synthetic oil or synthetic organic liquid as described herein including without limitations petroleum lubricants including the paraffins, aromatics, naphthenic oils, the synthetic oils, including the silicones, organic esters, polyglycols, phosphates, polyisobutylenes, polyphenol ethers, silicates, chlorinated aromatics, and fluorocarbons all as described herein.
The greases, solid lubricants, and metal working lubricants are also as described herein.
Various mixtures of each of the foregoing lubricants may be used including mixtures of 2 to about 3 or about 4 lubricants.
As noted before, additives described herein are also employed according to the invention. The composition of matter includes additives where petroleum oil or water is used as a lubricant, whereas the method of the invention of lubricating a surface includes the use of superabsorbent polymers in combination with the lubricants described herein, with or without the additives.
The material for decreasing friction between moving surfaces or lubricant employed according to the present invention also includes water or combinations of water and oil whether petroleum oils or synthetic oils as those materials are described herein. When water is used in combination with oil, it generally is employed as an emulsion whether a water in oil emulsion or an oil in water emulsion, both of which are well known in the art and are manufactured by methods that are similarly well known.
The invention also relates to a superabsorbent polymer combined with a solid or particulate inorganic lubricant such as those described herein including mixtures of solid or particulate inorganic lubricants especially mixtures of 2 to about 3 or about 4 solid or particulate inorganic lubricants.
In one embodiment, these inorganic lubricants comprise graphite, the chalcogenides of molybdenum, antimony, niobium, and tungsten, where the chalcogens comprise oxygen, sulfur, selenium, and tellurium and especially molybdenum disulfide, cobalt chloride, antimony oxide, niobium selenide, tungsten disulfide, mica, boron nitride, silver sulfate, cadmium chloride, cadmium iodide, borax, basic white lead, lead carbonate, lead iodide, asbestos, talc, zinc oxide, carbon, babbit, bronze, brass, aluminum, gallium, indium, thallium, thorium, copper, silver, gold, mercury, lead, tin, indium, or the Group VIII noble metals.
Chalcogenides of the non-noble metals may also be employed, especially the oxides, selenides or sulfides. In another embodiment the inorganic solid or particulate material comprises a phosphate such as a zinc phosphate, iron phosphate, or manganese phosphate, or mixtures thereof. Mixtures of the solid or particulate lubricants can be used, especially the 2 component 3 or about 4 component mixtures.
The superabsorbent polymers are also combined with a solid or particulate organic lubricant including mixtures of the organic lubricant and especially 2 to about 3 or about 4 component mixtures.
The solid or particulate organic lubricant comprises phenanthrene, copper phthalocyanine, a fluoroalkylene homopolymer or copolymer such as polytetrafluoroethylene, polyhexafluoroethylene, or copolymers of perfluoroethylene and perfluoropropylene. Homopolymers of polyvinylidene fluoride or copolymers of polyvinylidehe fluoride and hexafluoropropylene may also be employed as well as other fluorinated polymers which are well-known in the art. The solid or particulate organic lubricant may also include alkylene homopolymers or copolymers such as polymers of ethylene, propylene, isopropylene butylene, and isobutylene and the various copolymers thereof especially the 2 or 3 component copolymers thereof. The solid or particulate organic lubricant may also include a paraffinic hydrocarbon wax. Various mixtures of the solid or particulate organic lubricants may also be employed, especially the 2 to about 3 or about 4 component mixtures.
Combinations of the solid or particulate inorganic lubricant and the solid or particulate organic lubricant can also be employed, especially the 2 to about 3 or 4 component combinations. Both the solid or particulate inorganic lubricant and the solid or particulate organic lubricant may also be combined with room temperature liquid materials for decreasing friction between moving surfaces such as oil lubricants and/or synthetic lubricants as described herein or water or combinations of water and oil (including the synthetic lubricants) as described herein.
The solid or particulate inorganic lubricant or solid or particulate organic lubricant can also be used in combination with the superabsorbent polymers either as a mixture of powdered super absorbent polymer with solid or particulate organic lubricant or where the superabsorbent polymer is admixed with water or oil or both as described herein.
The superabsorbent polymer is also combined with a material for decreasing friction which comprises a metal working lubricant containing water or an emulsion of oil and water where the oil is either a petroleum oil or synthetic oil but especially a mineral oil and the emulsion comprises either a water in oil or an oil in water emulsion, the petroleum oils, and synthetic oils having been described herein. The metal working lubricant containing water may also comprise a solid or particulate inorganic or organic lubricant and water where the solid or particulate lubricants are as described herein.
The lubricant compositions of the present invention and the lubricant compositions used according to the method of the invention may comprise room temperature liquid compositions having SAE viscosities as described herein or may have the consistency of grease as that term and those consistencies are described herein.
Throughout the written description and claims, the lubricant is described as a material for decreasing friction between moving surfaces by which it is meant that the material comprises either a compound or composition of matter or mixtures of a compound and a composition of matter.
The average particle size of the particulate inorganic lubricant or organic lubricant or the superabsorbent polymer may be anywhere from about  less than 0.5 microns to about 300 microns or about 0.001 in. to about 0.3 in. and especially from about 0.005 in. to about 0.2 in. The superabsorbent polymer (as well as the lubricant composition) may also be in the form of flakes or sheets.
The lubricant composition can be either a liquid, including a viscous liquid, or gel, or a solid, whether rigid, semi-rigid or flexible at room temperature. Solid lubricant compositions also include a powdered lubricant composition. One of the outstanding features of the lubricant composition is that it can be shaped by any conventional molding or extruding process to form discs, sheets, rods, blocks, powders, or filaments, and especially solid lubricant compositions that can be formed to the contours of the surface or surfaces that are being lubricated.
Additionally, multiple dry films of the same or different lubricant composition may also be prepared, i.e. laminar structure lubricants where the layers of the laminate are anywhere from about 2 to about 25 mils thick. These laminates may also have some laminar layers based only on the superabsorberit polymer, or the lubricant, and the balance on the lubricant composition. Additionally, the same or different lubricant composition laminar layers may be used.
The superabsorbent polymer is used in combination with the lubricant in an amount anywhere from about 0.001 wt % to about 99 wt %, and especially from about 0.1 wt % to about 85 wt %, or from about 0.2 wt % to about 75 wt %, based on the combination of lubricant (with or without lubricant additives, or other additives) and superabsorbent polymer. In one experiment, the superabsorbent polymer is combined with about 350 times its weight of powdered graphite. Powders having an average particle size of about minus 325 mesh are taken up by some of the superabsorbent powders.
The lubricant and additives, when employed, are combined with the superabsorbent polymer by swelling the polymer either by itself or dispersed with the lubricant (and additives when employed), either in water or in a high humidity environment, e .g. 80% R.H.
Prior to, or after exposing the superabsorbent polymer to water or humidity, the polymer, in the form of a powder, flakes or granules is mixed with the lubricant in a conventional mixer, such as a HOBART(trademark) H mixer until a uniform dispersion is obtained. This process may be facilitated by employing a solvent or dispersant for the lubricant, preferably in some instances, one that will be easily driven off from the lubricant composition of the invention, such as a ketone, especially the lower alkyl ketones e.g. acetone MEK, MIBK, DIBK, and the like.
The lubricant then combines with, is entrapped by or is taken up by the superabsorbent polymer that has been swollen with water or in high humidity. The lubricant composition is then dried to remove the water, for example by placing it in a 27-38% R.H. environment, or under vacuum or at elevated temperatures. This removes substantially all of the water introduced in the first part of the process.
The lubricant composition, prior to removal of water as described herein, or after removal of water is shaped by molding or extruding, and in the case of forming powdered or granular lubricants, is ground to mesh in a conventional regrinding mill after the water has been removed.
Another outstanding feature of the lubricant compositions is their ability, under pressure to release the lubricant as a film or drop, or droplets, such as microdroplets and to recapture the released lubricant after pressure is released or ceases. The superabsorbent polymers of the lubricant compositions in this regard were discovered to have sponge like properties, even though no sponge like characteristics, such as porosity is visible to the naked or unaided eye, when examining the lubricant compositions. However, other matrix compositions can be formulated to have porous characteristics that are plainly visible.
A lubricant composition is made in the foregoing manner employing graphite, as noted above, or a 2 mol ethoxylate of isostearyl alcohol (AROSURF(copyright) 66 E2). Although the latter is used as a surfactant, it also has some lubricating characteristics and is to be considered as a lubricant as well for the purpose of the present invention.
Other solid fillers, adjuvants and diluents can be used in combination with the lubricants employed in the lubricant composition of the present invention, including surfactants, liquid extenders, solvents and the like.


The lead or lag relationship between the stator and rotor of a stepper motor is monitored on a continuing basis by an incremental encoder, in feed-back relation, and adjusts the lead or lag to within optimum range values to thereby prevent motor stalls and motor cogging.

This invention relates to stepper motors such as described within U.S. Pat. No. 6,967,425 entitled "Multi-Functional Electric Stepper Motor Assembly Having Increased Motor Torque" and U.S. Pat. No. 6,879,128 entitled "Method and Apparatus For Independently Controlling Each Phase of a Multi-Phase Step Motor", which patents are incorporated herein for purposes of reference.
One problem generally associated with such stepper motors is the possibility of motor stall when the torque generated by the associated load exceeds the motor rating.
A further problem occurs when the associated load causes the motor rotor to lead or lag the motor stator to such an extent as to cause the rotor to jump from one stable position to a new stable position, which is known as "cogging".
When such stepper motors are employed in commercial applications, the torque load generated by the associated equipment is estimated and the rating of stepper motors employed is then selected to exceed the estimated load by as high as fifty percent to defer the onset of such stalling or cogging.
One approach used to defer the occurrence of motor cogging is described within U.S. Pat. No. 5,250,867 entitled "Permanent Magnet Brushless DC Motor Having Reduced Cogging" wherein the motor stator is custom configured.
To employ a motor of equivalent load rating, a feedback circuit including a digital signal processor, such as that described within U.S. Pat. No. 6,121,744 entitled "Control Apparatus for Position Control Motor" and U.S. Pat. No. 7,081,730 entitled "Motor Controller System for Large Dynamic Range of Motor Operation" is usually required.
In most applications, the feedback circuit for preventing stalling is incorporated within the servo-motor circuit, per se, and cannot be used with existing motors
One purpose of the instant invention is to provide a simple arrangement whereby the position of the motor rotor to the motor stator is monitored and controlled on a continuing basis to defer the onset of stalling or cogging at all times of motor operation.
A further purpose of the invention is to provide an add-on rotor-stator control circuit for use with an existing motor arrangement when additional or changing loads are applied, as well as enabling an existing motor to accommodate a load which may from time to time exceed the rating of the motor.

Method and apparatus for eliminating stall and cogging in multi-phase stepping motors


An improved film cartridge construction comprised of several basic components (12, 14, 16 and 18) which are releasably connected to form a film cartridge 10, 88 or 90) and which can be recombined to form a wide variety of toys (114 and 126) and other articles 96 and 104).

It has long been known, in the photographic field, that packaging film cartridges has numerous advantages over conventional reels or cassette-packaged film, both in loading and processing. Thus, with cartridge film, the cartridge is loaded by simply dropping the cartridge into the camera, whereas with cassette or reel type film, it is necessary to securely attach the leading edge of the film to the windup spool and to thread the film into the camera. Furthermore, film cartridges can be removed and replaced at any time, even when partially exposed, whereas reel and cassette film cannot. Therefore, cartridge film has been widely accepted. On the other hand, conventional film cartridges are loaded with film at the film manufacturer and, in order to process the film, the cartridge must be broken to remove the film, leaving the fragments of the cartridge to be discarded. However, with current interest in environmental protection and concern over disposition of the vast amounts of waste which mankind is continuously creating, it is highly desirable to minimize or eliminate the waste produced by the film cartridge fragments. One step toward reduction of such waste is found in my prior patent, U.S. Pat. No. 4,887,111, issued Dec. 12, 1989, which discloses a film cartridge which is formed of a plurality of interchangeable parts which can be recombined for reuse as other film cartridges. This is a considerable step toward reducing waste from film cartridge fragments. Nevertheless, it is believed that further progress toward waste reduction is needed. Thus, none of the prior art film cartridges have been entirely satisfactory.

Convertible film cartridge and toy device


Methods to generate, and devices to use, an adaptive tone curve generation operation are disclosed. Tone curves so generated have been found to produce stable tone mapping in a wide range of operational environments, including during multi-exposure fused images (e.g., during high dynamic range image fusion). In general, techniques are disclosed that use a content-load histogram in combination with image capture device noise information to adaptively bound a tone curve's slope and, therefore, the resulting tone curve. As used here, a content-load histogram is a histogram that captures spatial, color or other information carried by an image's pixels at various gray levels.

This disclosure relates generally to the field of image processing and, more particularly, to various techniques to generate noise-constrained tone curves for use in real-time image processing.
Tone mapping is the process of remapping gray levels from a first or input image to different levels in a second or output image. Tone mapping is generally used to adjust the input image to more closely match the visual appearance anticipated by the human eye on a particular output device, and/or to better preserve image information when mapping an input image to a smaller output dynamic range. Global tone mapping refers to the situation where there is a single tone curve that maps input gray levels to output gray levels. Local tone mapping refers to the case where a single gray level in the input image maps to multiple gray levels in the output image depending on the spatial location and configuration of the input image. Tone mapping is used in almost all image processing pipelines, but is of particular importance when rendering high dynamic range images for a limited dynamic range output device (e.g., created for example by fusing multiple exposures). Illustrative devices having a limited output dynamic range include most consumer desktop and portable displays.


Disclosed is a container covering apparatus that permits one-handed unrolling and rolling of a cover over a container. Generally, the apparatus includes a roller and a rollable cover connected to the roller. Preferably, the cover is normally biased towards the unrolled position. The apparatus further includes a crank assembly having a crankshaft, a releasable locking mechanism, and a brake. The locking mechanism is engaged when the crankshaft is rotated in a first direction. When the crankshaft is rotated in the opposing second direction, the locking mechanism is disengaged, and the operator may engage the brake. In another embodiment, a covering apparatus including a crankshaft operatively coupled to a roller mechanism is disclosed. The crankshaft handle includes an arm portion and a gripping portion. The gripping portion is moveable between a first and second position. The handle is provided with a cam mechanism that biases the gripping portion into the first or the second position when in an intermediate position.

Open-topped cargo compartments, such as dump trucks, short vehicle trailers, storage bins and the like, are subject to having material stored therein fall or blow out. This can be particularly dangerous while the compartment is being transported. For instance, if portions of the load fall out onto a roadway (e.g., trucks or trailers hauling sand, gravel, dirt or similar materials), traffic accidents can occur, as well as damage to other vehicles and littering of the roadway. Wind effects can intensify the risk of inadvertent material loss. For instance, lightweight materials, such as plant clippings being taken to a landfill, mulch materials, or harvested plants like cotton, are susceptible to gusty winds, which may blow portions of the contents out of the vehicle or bin.
In many places, laws and regulations require the tops of such containers to be covered before they can be transported on public roadways to prevent material being blown out of the containers. Even where there are no laws regarding covering a load, it is beneficial for the driver to cover the load to reduce the possibility of damage to other property from escaping materials. Thus, tarpaulins are commonly used to cover the loads during transport. In addition, tarpaulins are often used to keep environmentally sensitive materials, such as asphalt, wheat, and the like dry and warm or cool during static storage as well as during transport.
Manually placing a tarpaulin onto an open-top container is both time-consuming and expensive. For this reason, the prior art has provided manual and automated tarpaulin covering systems. A typical manual drive system includes a tarpaulin disposed in a rolled fashion on a roller bar, and a crank box, which is disposed at a height that permits an operator to access and operate the device easily. If the roller is disposed at too great a height to be accessed directly, the covering system may include a chain drive that operatively connects the crank box and the roller bar. In such event, the crank box and roller bar typically are equipped with sprocket gears that engage a chain loop, thereby permitting the operator to roll and unroll the tarpaulin by operation of the crank box. In other embodiments, the crank box includes a crankshaft that is coaxial with the roller or that otherwise engages the roller without using a chain loop. In either case, the tarpaulin typically is normally biased towards its unrolled position, i.e., towards the position in which the tarpaulin covers the contents of the container. Often, the bias is created by way of a pair of spring-biased arms that are operatively connected to an end of the tarpaulin and that are biased towards the rear of the vehicle. The crank box may be equipped with a ratchet mechanism to lock the roller bar in position to prevent the tarpaulin from unrolling under the force of the spring-biased arms. The apparatus further may be provided with a brake system to prevent run-away opening when the ratchet mechanism is unlocked.
U.S. Pat. 5,129,698, to Cohrs at al. purports to disclose a system with lever operated locking and brake means in which the tarp cover system includes pawl and ratchet locking means for locking a tarp roll in a partially or fully rolled-up condition, in combination with dual levers. The levers are initially squeezed by one hand of the operator to release the pawl and ratchet locking means, and are subsequently pivoted by the same hand to brake the unwinding of the cover. The ratchet wheel is mounted on the crank shaft of the operating means, whereby the roller is continuously locked against inadvertent unrolling even when in a partially rolled condition.
The invention seeks to provide an improved covering apparatus. In preferred embodiments, the invention seeks to provide a covering apparatus that is operable using a single operator crankshaft handle, and that permits one-handed operation both to roll and to unroll the cover.


A thin film, intagliated phosphor screen structure includes an optical fiber bundle in which each of the fibers has its glass core etched below the level of its cladding sheath at the internal surface of the screen, and a phosphor layer is deposited as a thin film which fills in the core recesses. Preferably, the upper surfaces of the phosphor layers are formed with a spherical or parabolic shape, which is obtained by surface tension when the phosphor film is annealed. The upper surfaces of the phosphor layers may also be finished by polishing. An aluminum reflective layer may also be coated on the phosphor layer. The bottom walls of the cores are preferably etched to be convex or concave to provide a lens effect. The intagliated phosphor screen can transmit 90% to 95% or more of the light generated in the phosphor layers, for an output gain factor of 5 or more over conventional phosphor screens.

Luminescent phosphor screens are used in cathode ray tubes, for example, television display tubes, electron display devices, imaging devices, for example, image intensifier tubes, etc. Typically, a thin layer of phosphor material containing a luminescence activator is supported on a substrate. The phosphor layer is activated by impingement of an electron beam, and the resulting luminescence is transmitted through the glass substrate to the front of the display.
Phosphor screens, such as those used in image tubes, are made with phosphor powders. The powder is applied to a substrate glass plate or an optical fiber bundle by and one of several known methods, such as settling, brushing, spraying, etc. However, the use of powdered phosphors has numerous disadvantages. The powdered phosphors are not very adherent to the substrate. Typically, some sort of binder must be used to hold the phosphor particles to the substrate, which complicates the production process. Also, the powder is difficult to apply uniformly, leading to low process yields of acceptable units. The powders also have a high surface area which absorbs large amounts of gas from the phosphor constituents. This high outgassing characteristic is extremely undesirable for use in vacuum tubes where pressures of 10.sup.-10 torrs are achieved. Powdered phosphors also have a low optical resolution due to scattering off of the particles.
One proposal has attempted to apply powdered phosphors into intagliated (etched) recesses or wells formed in the core glass of the individual fibers of an optical fiber bundle in order to increase the resolution of the screen. Such an intagliated powdered-phosphor screen is described, for example, in "Intagliated Phosphor Screen Image Tube Project", by Richard J. Hertal, ITT Aerospace/Optical Division, prepared for NASA under Contract NAS5-26417, May 1982. However, this structure has a complicated manufacturing process and all of the other disadvantages of powdered phosphors.
Non-particulate, solid phosphor films have been used in display panel technology. The phosphor layer may be formed as a monocrystalline layer grown on a substrate by liquid phase epitaxy (LPE), or as a thin film deposited by evaporation, sputtering, or vapor deposition (MOCVD/MOVPE) techniques. Such phosphor layers have a relatively high thermal loadability, high resolution, and a low outgassing characteristic in a vacuum tube. However, the solid phosphor films suffer from low optical efficiency, making them undesirable for certain applications, such as image tube screens. The low optical efficiency of solid phosphor films is caused by large internal reflection losses within the film.
U.S. Pat. No. 4,264,408 entitled METHODS FOR APPLYING PHOSPHORS PARTICULARLY ADAPTED FOR INTAGLIATED PHOSPHOR SCREENS issued on Apr. 28, 1981 to J. D. Benham and assigned to The International Telephone and Telegraph Corporation, the assignee herein. This patent depicts a method for applying dry powder particles on an intagliated array of fibers. A thin layer of a heated thermoplastic is formed on the surface of the substrate to uniformly coat the etched pits. The thin layer is then heated to receive phosphor particles which become embedded in the plastic. The plastic layer is removed and the screen is then secured with a binder to fix the particles within the etched pits.
The problem of internal reflection losses in solid phosphor films is illustrated schematically in FIG. 1. An electron beam e.sup.- impinges on the phosphor layer through a metal layer, e.g. aluminum, which is optional in some applications. The electron beam activates an activator element, for example, copper in zinc-sulfide based phosphors, or cerium in yttrium-aluminum-garnet phosphors, which causes electrons to be released and photons from the nearby phosphor material to be emitted with a luminescence effect in all directions. Due to the difference in index of refraction between the phosphor layer and the substrate layer, such as glass, light rays which are incident at an angle greater than the critical angle CA are reflected laterally and become trapped and dissipated within the film. Another form of light loss is attributable to reflections from the substrate layer even within the cone (indicated by the dashed lines) of the critical angle CA, which increases as the light rays approach the critical angle.
As an example, the internal reflection loss due to the refraction difference for ZnS based phosphors grown on Corning type 7056 glass substrate can be in the range of 70% to 80% of the light emitted. Within the acceptance angle, the reflection loss can be another 10% to 25%, for a total loss of about 90% to 95% of the radiated energy. Such high losses result in lower phosphor efficiencies as compared to powdered phosphors. The result is that thin film phosphors have had limited application heretofore.
Some researchers have proposed forming reticulated structures in the phosphor layer to break up the waveguide effect and enhance light output. For example, U.S. Pat. No. 4,298,820 to Bongers et al. discloses the technique of etching V-shaped grooves in square patterns in the surface of the phosphor layer to obtain improved phosphor efficiency by a factor of 1.5. However, the etching process used in Bongers has been found to be impractical for large volume production.
Etching the activated portion of the phosphor layer, with reticulations in the form of trapezoid- or truncated-cone-shaped mesas and overcoating with a reflective aluminum film to form light confining surfaces, has been proposed in the article entitled "Reticulated Single-Crystal Luminescent Screen", by D. T. C. Huo and T. W. Huo, Journal of Electrochemical Society, Vol. 133, No. 7, pp. 1492-97, July 1986, and in "RF Sputtered Luminescent Rare Earth Oxysulfide Films", by Maple and Buchanan, Journal of Vacuum Technology, Vol. 10, No. 5, pg. 619, Sep./Oct. 1973. These trapezoidal mesas improve the light output by a factor of about 2, whereas a factor of 6 or higher would represent output of most of the emitted light. The light output factor could be increased if the mesa size could be made less than 5 microns and the shape made with the optimum reflection angle. However, such a small mesa size requires high lithography resolution and is limited by diffraction from the lithography mask. Crystalline phosphors will also preferentially etch along crystalline planes which are different from the optimum slope angle for the trapezoid shape. Thus, application of trapezoidal mesas and reticulated layers has also been limited.

Thin film intagliated phosphor screen structure


The invention provides a process for making a let-down of glass fiber reinforced composite comprising a polymer matrix and from 5 wt. % to about 60 wt. % of reinforcing fibers long fibers. The fibers are incorporated in the let-down as a concentrate of pultruded composite of substantially parallel fibers and thermoplastic polyamide where fiber length equals pellet length. The fibers in the let-down have improved dispersion and orientation in the final thermoplastic polymer matrix thereby providing substantially improved physical properties from the forming of the fiber reinforced pellet with a modified pellet polymer matrix. The long fibers are incorporated as a concentrate pellet in the final matrix polymer by mixing pellets with the final polymer compound in a heated extrusion mixing zone used to convey a composite melt into a shaping zone, whereby the mixing under heat and rotational shear disperses the long fiber-reinforced pellets into the let-down matrix polymer.

The invention relates to thermoplastic fiber reinforced composites utilized in molding and extrusion, and in particular, composites having as a matrix resin polyamide polymers.
There has been growing interest in the use of long fiber reinforced thermoplastic composites as materials of construction because of the excellent physical properties inherent in a reinforcing network of fibrous materials such as glass, carbon, boron and alumina fibers embedded in a thermoplastic, as opposed to a thermosetting polymer matrix. Improvements in thermoplastic pultrusion techniques have occurred since the early 80""s for directly impregnating thermoplastic high polymers with a high degree of wet-but of continuous fiber rovings so that chopped pellets of 10 mm and longer can be used in let downs with thermoplastic resin compounds. Chopped pellets of good quality now can readily incorporated in molding compounds which are fed directly into extruders feeding injection molds or extrusion dies.
Long fiber reinforced composites of high temperature engineering resins, e.g., polyarylethers, especially polyetherketones and polyethersulphones are also known. For example, carbon fiber reinforced polycarbonate, and polyetheretherketone composite materials have found increasing commercial application. Polypropylene and nylon have generated the highest commercial volumes to date among the thermoplastics, especially directed to automotive end-uses.
Resin structures reinforced with long ( greater than 5 mm) fibers have superior processing properties and often better physical properties at the same degree of fiber loading, as compared to those reinforced with short (2 mm) fibers. The long fiber compounds are generally manufactured by a so-called pultrusion method in which a continuous reinforcing fiber bundle is impregnated with a thermoplastic resin while pulling fiber roving bundles through a cross-head extruder and then through a die (U.S. Pat. No. 3,993,726), or a continuous reinforcing fiber bundle is immersed in a thermoplastic resin melt to wet it while it is drawn and then pulled through a die.
The following patents relate to the formation of long fiber reinforced pultrusion composites: U.S. Pat. Nos. 4,541,884, 4,549,920, 4,559,262, 4,892,600, 5,019,450, 5,213,889.
U.S. Pat. No. 3,993,726 describes a process for the continuous production of articles of thermoplastic resin reinforced with long fibers of glass. According to the method described, the roving is impregnated with a mixture of wetting thermoplastic resin and reinforcing thermoplastic resin in a crosshead die fed by an extruder. The fibers are impregnated by first expanding the fibers of the roving and coating the expanded fibers in a crosshead die and passing the fibers and the thermoplastic mixture through a bar zone so that the material thoroughly penetrates into each fiber. This system is not completely satisfactory, since the wetting polymer dilutes in the other polymer and physical properties are lost.
U.S. Pat. No. 4,937,208 discloses a process for producing thermoplastic resins reinforced with long fibers in which rovings are impregnated with a wetting thermoplastic polymer by means of a die and a baffle zone, then taking up the impregnated rovings in a second die where they are then covered with a thermoplastic polymer. As explained, the wetting thermoplastic polymer must be compatible with the coating thermoplastic polymer. Suggested combinations disclosed were grafted high-density polyethylenexe2x80x94low-density polyethylene, grafted high-density polyethylenexe2x80x94ethylene-vinyl acetate (EVA) copolymer, grafted EVAxe2x80x94polyvinyl chloride, grafted polypropylenexe2x80x94polypropylene, sequenced poly(ether-amide) copolymerxe2x80x94polyamide functonalized polyamide (for example xcex1,xcexa9-diamines, xcex1,xcexa9-diacids, xcex1-amine-xcexa9-acid, monoamine)xe2x80x94polyamide, modified EVAxe2x80x94EVA or low-density polyethylene (PEbd).
U.S. Pat. No. 4,783,349 discloses a method of producing a fiber reinforced structure by melt impregnation of continuous fibers with a thermoformable polymer melt comprising pre-wetting the filaments of the fibers with a composition containing a melt plasticizer for the thermoformable polymer, prior to introducing the pre-wetted fibers into the melt, optionally removing the plasticizer when the composition contains a polymer miscible with plasticizer to leave polymer coated filaments and introducing the pre-wetted filaments into a polymer melt, optionally a polymer melt containing a metal plasticizer for the melt and preferably removing the plasticizer from the composition by volatilization. The pre-wetted polymer coated filaments can be let down into a compounding extruder running with the primary thermoplastic or processed directly in an injection molding apparatus being fed with a blend of fiber-reinforced, and non fiber-reinforced compound for use in processes other than direct melt impregnation. They can be used in the process known as film stacking impregnation or in processes involving initial impregnation using particulate polymers or alternatively in conventional extrusion compounding.
Nylon polymers have also been stabilized by incorporating stabilizing materials directly into the polymer chain. For example, epsilon-caprolactam may be polymerized in the presence of water, carboxylic acids and hindered piperidine derivatives (polyalkylpiperidines) to form a modified nylon 6 polymer that is stabilized against heat and light degradation. Such a stabilized polymer is described in PCT Application WO 95/28443 published Oct. 26, 1995.
Difficulties in the pultrusion of engineering resins, e.g. polyamide, result from the poor wet-out of the fibers. This problem is not so severe in the case of polypropylene. Some approaches to improving the pultrusion of polypropylene have been disclosed whereby the reinforcing fiber roving is treated in a separate step with a wetting thermoplastic polymer or solution thereof, such as a with a polyolefin modified by grafting with an ethylenically unsaturated polycarboxylic acid. However, this method requires a selection of specialized wetting polymers which must be substantially compatible with the matrix polymer, as well as a limit in the highest flexural or tensile modulus, generally, not to mention the cost and environmental impact of such a method. Recently, higher melt-flow polypropylene products have become the standard material for the one-pass pultrusion at high (30 vol. %) fiber loadings.
For a variety of reasons, such as the need to reduce costs and to fabricate lighter structures, improved flexural and tensile modulus are desired from less costly polymer composites. The limitations of flowability for fiber-reinforced composites present problems particularly in the injection molding of large surface area articles using a composite wherein the fiber content exceeds 15, 20 and even greater than 30 volume percent. Desirable thermoplastic materials, such as polyamides, in particular the phthalamide-types which otherwise provide inherently high modulus, and physical properties at high in-service temperatures have limits on moldability, especially in light of the molding tonnage available to molders. The high volume content of fibers results in relatively little polymer being available at the surfaces of the work pieces to be joined. Differences in the dispersion patterns of the long fibers results in variations in resulting physical properties of the molded composite.
In the manufacture of long fiber reinforced pellets of conventional engineering resins having acceptable end-use physical properties have melt viscosities in excess of 100 Ns/m2. Adequate wetting of the fibers in a pultrusion process with a melt of such high viscosity is not easily achieved. Problems of fiber roving breakage, lowering of line speeds to promote wet-out, and polymer degradation are possible. Any attempts to improve production by reducing the pultrusion matrix polymer melt viscosity, such as by increasing the melt temperature runs a greater risk of operating in an unstable thermal window. Other methods to reduce melt viscosity of the pultrusion matrix polymer by blending the matrix polymer with higher melt-flow materials is accompanied by undesired loss in physical properties, greater complexity and/or cost.
For molding or extrusion of shaped articles from long-fiber reinforced composites in which a fiber-reinforced concentrate is let down with additional matrix resin compound, there is a second added work history experienced by the fiber reinforced concentrate. This results inevitably in fiber breakage (attrition) and an inherent loss in flexural and tensile moduli, and/or impact strength. Improvements in the resulting physical properties of the final composite are sought.
It would be desirable to improve the physical properties of long fiber reinforced thermoplastic composites made by the method of letting down long fiber concentrates wihout resorting to harsh conditions, or blending with polymeric flow improvers therefore.
The invention provides a process for making a letdown of glass fiber reinforced composite comprising a polymer matrix and from 5 wt. % to about 60 wt. % of reinforcing fibers long fibers. The fibers are incorporated in the let-down as a concentrate of pultruded composite of substantially parallel fibers and thermoplastic polyamide where fiber length equals pellet length. The fibers in the let-down have improved dispersion and surprisingly greater, as opposed to less orientation in the final thermoplastic polymer matrix relative to prior art long fiber composite, thereby providing substantially improved physical properties from the forming of the fiber reinforced pellet with a modified pellet polymer matrix. The long fibers are incorporated as a concentrate pellet in the final matrix polymer by mixing pellets with the final polymer compound in a heated extrusion mixing zone used to convey a composite melt into a shaping zone, whereby the mixing under heat and rotational shear disperses the long fiber-reinforced pellets into the let-down matrix polymer.
The long fiber reinforced pellets comprise a modified pellet polymer matrix according to (a) or (b),
(a) the pellet matrix polymer is modified in the polymer polymerizing process by introducing an effective amount of a compound according to (A)-(I) or where applicable, a hydrolyzate thereof, with precursors of the matrix polymer, and method
(B) whereby the long fiber pellet is formed with a pellet matrix polymer that contains an effective amount of compounds selected from (B)xe2x80x94(XX) in intimate contact with the continuous fiber during the formation of the long fiber pellets.

Method for improving fiber dispersion and orientation in let-downs of long fiber reinforced composites


A trim element includes a body defining an outer surface of the trim element, at least part of the body being deformable and having a deformable guide surface extending in a first direction. The trim element further includes at least one actuating element having an actuating segment extending non-rectilinearly in the first direction. The actuating segment cooperates with the guide surface in an actuating area, the guide surface adopting the shape of the actuating segment in the actuating area. The actuating segment is movable relative to the body in the first direction such that the actuating area is movable and the body deforms when the actuating element is moved in the first direction.

Trim elements with a deformable outer surface are known. Such trim elements for example make it possible to modify the position of a support surface, such as an armrest, protruding from the outer surface, or to modify the appearance of the outer surface based on specific uses of the vehicle.
Such a modification of the shape of the outer surface can be obtained by arranging inflatable elements below the outer surface and controlling the inflation of these elements to create a raised area opposite an inflated element.
Such a pneumatic system is, however, not satisfactory for several reasons.
It is in fact difficult to obtain the desired rigidity of the outer surface over an inflated element, which makes the system relatively unsuitable for forming a support surface. Furthermore, the feel of the outer surface is not satisfactory, since it is not uniform over the entire outer surface, the latter being rigid in the non-inflated areas and less rigid over an inflated element.
Furthermore, while a pneumatic system is suitable for forming raised areas protruding from the outer surface, it is less practical for forming hollow areas.

Trim element comprising a deformable outer surface


The present invention relates to a process for the production of derived timber products by applying a storage-stable binder to materials containing lignocellulose and heating this mixture under pressure. These storage-stable binders comprise a polyisocyanate and an amine catalysts. The invention also relates to these storage-stable binders.

This invention relates to a process for the production of derived timber products. This process comprises applying a binder to lignocellulose containing materials and heating this mixture under pressure. Suitable binders are storage-stable and comprise a polyisocyanate and an amine catalyst.
Derived timber products, for example chipboard, laminated board or other moldings are usually produced by hot pressing the inorganic or organic raw material, for example a mass of wood chips, wood fibers and/or other material containing lignocellulose, in a xe2x80x9cmixed gluingxe2x80x9d process with polyisocyanates and water, optionally polyols or other binders such as urea/formaldehyde or phenol/formaldehyde resins. Using polyisocyanates as the binder improves the stability and moisture performance of the products and enhances the mechanical properties thereof. As disclosed, for example, in DE-OS 21 09 686, polyisocyanates furthermore possess wide-ranging processing advantages.
Catalysts of the type known per se from polyurethane chemistry, for example those stated in DE-OS 28 54 384, pp. 26-29 and 31-33, may in principle also be used in prior art processes (c.f. for example DE-AS 27 11 958) in order to shorten pressing times. This is of particular importance in xe2x80x9cone-daylightxe2x80x9d presses. However, when catalysts are used, due to the immediate onset of catalyst action on the reactive NCO groups, unwanted foaming and premature setting generally occur during mixing of the components and storage of the isocyanate-glued chips. Consequently, it is generally necessary to dispense with the use of catalysts and accept longer pressing times.
EP-A 133 680 discloses a process for the production of derived timber products using polyurethanes as binders, in which tertiary or quaternary ammonium phosphonates or quaternary ammonium phosphates are used as heat-activated catalysts. However, the reduction in pressing time observable when these catalysts are used is not sufficient for economic performance of the process. Sufficiently short pressing times likewise cannot be achieved with the processes described in DE-OS 42 29 396 and DE-OS 34 38 735 for the production of chipboard or fiber board using polyisocyanates as the binder.
DE-OS 196 03 330 describes a process for the production of derived timber products using polyisocyanates as the binder which also use a latent catalyst system, in which the catalysts used are ammonium salts which are obtained by reacting amines with malonic acid. These activated binders effectively reduce pressing times and also function at elevated chip temperature. However, due to the deficient storage stability thereof in isocyanates, the catalyst must be added separately to the isocyanate directly before gluing. This separate addition entails additional plant costs and possible sources of error in the production process.
There was accordingly a need for a single component polyisocyanate binder containing catalyst which remains stable at elevated temperature over an extended period and permits pressing times to be shorted during hot pressing. Binder systems based on polyisocyanate and amine catalysts have now been discovered which are ideally suited to this purpose.
The present invention provides a process for the production of derived timber products comprising
(a) applying a storage-stable binder comprising one or more polyisocyanates and one or more amine catalysts to materials containing lignocellulose; and
(b) heating the product of (a) under pressure, thereby forming the resultant derived timber products.
Suitable amine catalysts to be used according to the invention preferably comprise those compounds which contain dimorpholino groups. Dimorpholinodiethyl ether and dimorpholinopolyethylene glycol are particularly preferred amine catalysts for the present invention. Dimorpholino compounds have already variously been suggested as storage-stable additives to moisture-curing MDI prepolymers or PMDI/epoxy resins (see, for example, EP-A 226 287, EP-A 668 302, EP-A 732 385, U.S. Pat. No. 5,075,405, EP-A 811 645 and/or WO 94/18265, the disclosures of which are herein incorporated by reference). EP-A 668 302 is believed to correspond to U.S. Pat. No. 5,550,191 which, at column 4, lines 45-69, discloses MDI prepolymers. More specifically, this reference discloses that the polyisocyanate and polyol, polyamino or polymercapto components are combined proportions so as to yield a urethane prepolymer characterized by an isocyanate content of from about 0.25 to 15%, preferably to about 10%, and most preferably from 1.5 to 5%. EP-A 732 385 is believed to correspond to U.S. Pat. No. 5,616,625 which, at column 5, lines 25-48 describes that the polyisocyanate and polyol, polyamino or polymercapto components are combined proportions so as to yield a urethane prepolymer characterized by an isocyanate content of from about 0.25 to 15%, preferably to about 10%, and most preferably from 1.5 to 5%. EP-A 811 645 is believed to correspond to U.S. Pat. No. 6,090,307 which, at column 3, lines 36-38, discloses prepolymer components having NCO group contents of between 4 and 20%, preferably between 6 to 18% and in particular between 7 and 13% by weight. However, the use of dimorpholino compounds in unmodified isocyanates for the production of storage-stable binders which are suitable for the production of derived timber products by hot pressing was not previously known.
The binders of the present invention generally contain from 0.01 to 30% by weight of catalyst, based on 100% by weight of the isocyanate. In a preferred variant, they contain 0.02 to 2% by weight, particularly preferably 0.05 to 1% by weight, based on 100% by weight of the isocyanate.
Addition of the catalyst to the isocyanate and subsequent mixing must proceed in the absence of moisture. The mixed binder system may be stored at temperatures of up to 40xc2x0 C. for at least two months, and may also briefly be exposed to temperatures of up to 60xc2x0 C. without there being any impairment of the binder properties.
Suitable isocyanate components which may be considered for the performance of the process according to the invention comprise aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, as have been described by W. Siefken in Justus Liebigs Annalen der Chemie, 562, pp. 75-136, for example those of the formula
Q(NCO)n
wherein:
n: represents a number from 2 to 4, preferably 2; and
Q represents an aliphatic hydrocarbon residue having 2 to 18 carbon atoms, preferably 6 to 10 carbon atoms, a cycloaliphatic hydrocarbon residue having 4 to 23 carbon atoms, preferably 5 to 13 carbon atoms, an aromatic hydrocarbon residue having 6 to 25 carbon atoms, preferably 6 to 13 carbon atoms, or an araliphatic hydrocarbon residue having 8 to 15 carbon atoms, preferably 8 to 13 carbon atoms.
Some examples of suitable polyisocyanates for the present invention, include compounds such as, for example, 4,4xe2x80x2-diphenylmethane diisocyanate, 1,3- and 1,4-phenylene diisocyanate, 2,4- and 2,6-tolylene diisocyanate and any desired mixtures of these isomers, 2,4xe2x80x2- and/or 4,4xe2x80x2-diphenylmethane diisocyanate, and any desired mixtures of these isomers or the polymeric types from this series.
Industrially readily available polyisocyanates are generally preferred. Such polyisocyanates include, for example, 2,4- and 2,6-tolylene diisocyanate and any desired mixtures of these isomers (xe2x80x9cTDIxe2x80x9d), and particularly preferably polyphenylpolymethylene polyisocyanates, as are produced by aniline/formaldehyde condensation and subsequent phosgenation (xe2x80x9ccrude MDIxe2x80x9d). The polyisocyanates used may optionally also be modified. More highly cyclic isocyanates of the diphenylmethane diisocyanate series (pMDI grades) are particularly preferably used.
The process according to the invention may also be performed using prepolymers comprising terminal isocyanate groups (i.e. NCO-terminated prepolymer) and having an average molecular weight of approx. 275 to 2000, as are obtained in a manner known per se by reacting relatively high molecular weight or low molecular weight polyols with an excess of a suitable polyisocyanate.
Polyols which may be used in the preparation of the prepolymers include, for example, any relatively high molecular weight polyols conventionally used in polyurethane chemistry, in particular compounds comprising two to eight hydroxyl groups, especially those of molecular weights from 400 to 10,000, preferably from 550 to 5,000. Suitable examples of such compounds include polyesters, polyethers, poly-thioethers, polyacetals, polycarbonates and polyesteramides which comprise as a rule two to eight, but preferably two to four, hydroxyl groups, as are known per se for the production of homogeneous and cellular polyurethanes.
Suitable raw materials containing lignocellulose, which may be bound with the polyisocyanate/activator formulation according to the invention, include, for example, wood, bark, cork, bagasse, straw, flax, bamboo, esparto grass, rice husks, sisal and coconut fibers. The material may here assume the form of pellets, strands, chips, fibers or flour, and may have a water content of, for example, from 0 to 35% by weight, preferably of from 5 to 25% by weight, based on the 100% by weight of the lignocellulose containing material. The material is combined with the binder in a quantity of 1 to 100% by weight of binder, preferably of 2 to 12% by weight of binder, based on 100% by weight of the lignocellulose containing material. Generally, the lignocellulose containing material and the binder are combined under the action of pressure and heat, and are pressed into boards or moldings.
Multi-ply boards or moldings may also be produced in a similar manner from veneers, paper or fabrics. Multilayer boards or moldings made from veneers with central cores of strips, battens or bars, known as xe2x80x9cwood core boardxe2x80x9d, may be produced according to the invention by treating the veneers as described above with the isocyanate/activator formulation, and then pressing them with the central plies, generally at elevated temperature and elevated pressure. Temperatures of 80 to 250xc2x0 C., in particular of 100 to 220xc2x0 C., are preferably maintained during this process. The initial pressing pressure is also in this case preferably between 5 and 150 bar. The pressure generally declines towards 0 bar over the course of the pressing operation.
The polyisocyanate/activator formulations may also be used according to the invention in combination with the above-described polyhydroxyl compounds in an NCO/OH ratio of 1.1:1 to 10:1, and preferably of 1.5:1 to 5:1. It is possible in this case to use the two components separately or as a reactive mixture. Such combinations of polyisocyanate and polyhydroxyl compounds have practical significance as binders such as, for example, for binding cork scrap. It is also possible to add per se known blowing agents in a quantity of approx. 0.5 to 30% by weight, based on 100% by weight of the the binder composition (or impregnating agent). It is also possible to add other additives which influence foaming or the chemical reaction between polyisocyanates, lignocellulose containing material and any optionally present polyhydroxyl compounds. Such additives include, for example, stabilisers, which may be added in a quantity of 0.05 to 10% by weight, based on 100% by weight of the binder composition (or impregnating agent).
The polyisocyanate/activator formulations to be used as binders according to the invention may also be combined with, for example, the aqueous solutions of condensation products prepared from formaldehyde with urea and/or melamine and/or phenol hitherto predominantly used in the derived timber products industry (mixed gluing), as well as with other hitherto less commonly used binders and impregnating agents, such as, for example, spent sulfite liquor (lignin sulfonate or other industrial lignin solutions from wood pulping), or tanning agent type compounds such as tannin, where a mixing ratio (by weight) of the binders according to the invention with these additional binders of between 1:10 and 10:1, preferably of between 1:5 and 5:1, may be maintained and wherein the binders according to the invention and the additional binders may be used either separately or also as a mixture.
Such combinations are particularly advantageous in the production of multilayer boards having special properties. The outer layers may, for example, be combined with conventional adhesives (alone or together with the polyisocyanate binder) and one or more internal layers may be combined with the polyisocyanate binder to be used according to the invention (alone or together with conventional adhesives) and then pressed together.
Due to their outstanding mechanical properties, the boards or moldings based on raw materials containing lignocellulose or other organic and/or inorganic raw materials and produced according to the invention are primarily suitable for use in construction. In order to impart the resistance to fungal attack, insect infestation or the action of fire which is generally required for such boards or moldings, conventional commercial additives, for example, aqueous polyethylene emulsions of organic or inorganic protective agents, may be added in pure form or as a solution in a quantity of approx. 0.05 to 30% by weight, preferably of 0.5 to 20% by weight, based on 100% by weight of the binder composition. Solvents which may be considered are water or organic solvents, residual oils from petroleum processing, chlorinated hydrocarbons and the like. The quality of the gluing is not generally impaired as a consequence. Advantageously, unlike in phenol/formaldehyde resin glued boards, neither salt efflorescence nor xe2x80x9cbleedingxe2x80x9d occur in the materials produced according to the invention.
Due to the elevated adhesive power of the binders according to the invention, the moldings impregnated or bound therewith frequently have a tendency to adhere to the surfaces of the hot presses or molds. This may be avoided by release agents, which are added to the binder. Another solution involves applying the release agents in pure form or as a solution onto the metallic surfaces which come into contact with the pressed articles or onto the surface of the molding. External release agents which may be considered are any substances hitherto proposed for this purpose. Preferred compounds according to DE-OS 23 25 926 are, however, those which catalyse isocyanurate formation in isocyanates such as, for example, phenol Mannich bases, derivatives of hexahydrotriazine or alkali metal salts of carboxylic acids and/or soaps, optionally in solution, such as, for example, aqueous diethylene glycol. Another approach to preventing adhesion involves arranging a release layer between the pressed article and metallic surface of the press, wherein the release layer may consist of webs, films or comminuted forms of various raw materials (for example plastics, paper, wood, metal). As has already repeatedly been mentioned, substantial improvements, with regard both to mechanical properties and to processing, may be achieved in chipboard production with the isocyanate binders to be used according to the invention in comparison with conventional binders based on phenol/-formaldehyde or urea/formaldehyde resins. In the case of wood chipboard, it is accordingly possible either to achieve an increase in flexural rigidity of up to 50% (combined with an improvement in other mechanical properties) when using the same quantity of the presently required isocyanate binder as required for phenol/formaldehyde or urea/formaldehyde resins. Alternatively, it is possible to achieve identical mechanical properties as result from phenol/formaldehyde or urea/formaldehyde resins while using the presently required isocyanate binders in an amount of from 25 to 70% less.

Storage-stable isocyanate binders containing latent catalysts


A glazing comprising a sheet of glass, a film of damping material, and a rigid sheet, the assembly being laminated and comprising one or more exciters fastened to the glazing.

The present invention relates to glazing units used as sound generators.
Most audiovisual equipment available on the market (television sets, computers, mobile phones) comprise an image display screen and at least one sound generator. The display screen is usually coated with a protective glazing, customarily formed by a single or laminated glass panel. In the majority of cases the sound generator comprises one or more loudspeakers separated from the screen. The separated arrangement of the loudspeakers and the screen results in a bulky arrangement.
To reduce the bulkiness it has been proposed to use the screen itself as resonator, on which one or more exciters are mounted, the entire assembly forming the sound generator.
However, so far the practical implementation of such audiovisual screens has encountered numerous difficulties associated with the production of glazing exhibiting all the required qualities. Thus, in the "Magic Sound®" technology of Glas Platz GmbH & Co., the glazing is a glass panel with a thickness of scarcely 0.3 mm. The use of a glass panel with such a small thickness is determined by the acoustic properties of the glass. With respect to mechanical resistance, in particular impact resistance, it is not appropriate for the production of screens of large dimensions (computer or television screens).
In the "SoundVu" technology of NXT plc, it is proposed to produce the sound generating glazing from polymer material with suitable acoustic properties, in particular polycarbonate. However, in use such glazing units have very poor optical qualities and a poor mechanical resistance, primarily to scratches
The invention aims to remedy the problems and disadvantages of known glazing units.
More particularly, the invention aims to provide a sound generating glazing that combines good acoustic properties, an excellent optical quality and good mechanical properties, in particular a good impact resistance and good scratch resistance.