MXPA98009047A - Composition of polyurethane thermoplastic su - Google Patents

Abstract

The present invention provides a thermoplastic polyurethane (TPU) composition comprising a blend capable of adhering to a thermoplastic substrate material wherein the blend of the thermoplastic polyurethane comprises: a) from 3 to 200 parts of a styrene / alpha-methylstyrene terpolymer / acrylonitrile / alkyl acrylate of 1 to 6 carbon atoms with a glass transition temperature (Tg) of less than 0 ° C, b) 100 parts of a thermoplastic polyurethane produced from a diisocyanate, a diol of 2 to 10 carbon atoms , and a polyol based on polyether and / or polyester, c) from 0 to 50 parts of different additives, including lubricants, pigments, stabilizers, and

Description

"SOFT THERMOPLASTIC POLYURETHANE COMPOSITION" 1. FIELD OF THE INVENTION The invention relates to a mild thermoplastic polyurethane (TPU) composition, and more particularly, to a low Shore A hardness TPU composition, that is, soft, having high abrasion resistance. 2. BACKGROUND OF THE INVENTION Rigid thermoplastic materials such as ABS, nylon 6 loaded and filled with glass and polycarbonate, are used for a variety of engineering and / or structural applications such as power tool housings, and baggage grips or handles, gear shifts, automotive pedals, etc. For many of these applications, there is a need to cover over or bond these articles to a soft elastomeric layer. This layer serves to provide an ergonomic, comfortable feel, reduced slippage and increased abrasion resistance. Ideally, this combination of "hard" and "soft" materials is produced through a thermoforming operation such as co-injection molding, multi-layer extrusion or blow molding. U.S. Patent No. 5,149,979 is directed to a shaped article and method for making this article. The article consists of a base produced from a first thermoplastic polymer. An attachment produced from a second thermoplastic polymer is welded to the upper part of the base. One or both of the first polymer and the second polymer should contain from 5 percent to 75 percent by weight, based on the mixture, of an olefin homopolymer and / or copolymer. Typical examples would include an engineered thermoplastic power tool body with a handle grip produced from an elastomer such as TPU, Santoprene or the like. Unfortunately, the article disclosed in the "979 Patent" provides insufficient abrasion resistance in the elastomeric portion as well as being too hard for most uses that would require an elastomeric overlay. Until now, most of the thermoplastic elastomers with the required softness (<Shore A 90) to be useful as a soft coating, including propylene and EPDM polymers based on ethylene, styrenic block co-ter- or copolymers and plasticized PVC had insufficient adhesion to the rigid thermoplastic substrate unless they were fixed using separate adhesives or mechanical interlacing. Unfortunately, these TPEs have insufficient abrasion resistance for engineering applications. Even with the desired Shore hardness, good adhesion and abrasion resistance, plasticized TPU (TPU mixed with phthalate esters such as DOP) is unacceptable due to the tendency of the plasticizer to migrate to the thermoplastic substrate and cause cracking. effort. 2. COMPENDIUM OF THE INVENTION The present invention provides a thermoplastic polyurethane (TPU) composition comprising a blend capable of adhering to a thermoplastic substrate material wherein the thermoplastic polyurethane blend comprises: a) from 3 to 200 parts of a styrene / alpha-methylstyrene terpolymer / acrylonitrile / alkyl acrylate of 1 to 6 carbon atoms, with a glass transition temperature (Tg) lower than 0 ° C; b) 100 parts of a thermoplastic polyurethane produced from a diisocyanate, a diol of 2 to 10 carbon atoms and a polyol based on polyether and / or polyester; and c) from 0 to 50 parts of different additives including lubricants, pigments, stabilizers, etc. 4. DESCRIPTION OF THE PREFERRED MODALITIES The present invention is a TPU compound having a Shore A hardness of < 90. Preferably, Shore A hardness is less than or equal to 80 and greater than 65. The TPU compound comprises: a) from 3 to 200 parts of a styrene / alpha-methylstyrene / acrylonitrile / alkyl acrylate terpolymer from 1 to 6 carbon atoms, with a glass transition temperature less than 0 ° C; b) 100 parts of a thermoplastic polyurethane produced from a diisocyanate, a diol of 2 to 10 carbon atoms and a polyol based on polyether and / or polyester; and c) from 0 to 50 parts of lubricants, pigments, stabilizers, etc. The resulting composition has a Shore A hardness of < 90. The relative hardness of elastic materials such as rubber or soft plastic can be determined with an instrument called the Shore A durometer. If the indenter completely penetrates the sample, a reading of 0 is obtained, and if penetration does not occur, a reading of 100 results. The reading is dimensionless. The aforementioned materials are combined together in a melting process, preferably using a twin screw extruding apparatus. Optionally, one or more ultraviolet ray stabilizers, one or more compatibilizers and one or more additives that are selected from the group consisting of lubricants and inhibitors, stabilizers against hydrolysis, thermal stabilizers, flame retardants, dyes, pigments, fillers or fillers Inorganic and / or organic and reinforcing agents can be added to the composition. The TPUs usable in accordance with the present invention can be prepared by reacting a) organic diisocyanates, preferably aromatics, in particular 4, '-diphenylmethane diisocyanate, with b) polyhydroxy compounds, preferably essentially linear polyhydroxy compounds having molecular weights from 500 to 8000, in particular polyalkylene glycol polyadipates having from 2 to 6 carbon atoms in the alkylene residue, and molecular weights from 500 to 6000, or polytetrahydrofuran containing hydroxyl having a molecular weight of 500 to 8000, and c) diols as chain lengthening agents having molecular weights of from 60 to 400, in particular, 1, -butanediol. in the presence of d) catalysts and, optionally e) auxiliaries and / or f) additives at elevated temperatures. Organic diisocyanates suitable for use in the manufacture of the TPUs of the invention are, for example, aliphatic, cycloaliphatic and preferably aromatic diisocyanates. Specific examples are: aliphatic diisocyanates, such as 1,6-hexamethylene diisocyanate, 2-methyl-lx 5-pentamethylene diisocyanate, 2-ethyl-1,4-butylene diisocyanate and mixtures of at least two of these aliphatic diisocyanates , cycloaliphatic diisocyanates such as isophorone diisocyanate, 1-cyclohexane diisocyanate, 1-methyl-2,4-cyclohexane diisocyanate and l-methyl-2,6-cyclohexane diisocyanate, and the corresponding isomer mixtures, 4-diisocyanate, 4'-, 2,4'- or 2,2'- or 2'-2-dicyclohexylmethane, and the corresponding isomeric mixtures, and preferably aromatic diisocyanates such as 2,4'-toluylene diisocyanate, diisocyanate mixtures of 2, 4- and 2,6-toluylene, 4,4'-2,4'- and 2,2'-diphenylmethane diisocyanate, mixtures of 2x4'- and 4x4'-diphenylmethane diisocyanate, 4,4'- diisocyanates and or 2,4'-diphenylmethane modified with urethane, 4,4 '-diisocyanato-1,2-diphenylmethane, mixtures of 4,4'-, 2,4'- and 2,2'-diisocyanato-1,2-diphenylmethane or, preferably those having a content of 4,4'-diisocyanate-1,2, diphenylethane of at least 95 weight percent, and 1,5-naphthalene diisocyanate. Preference is given to the use of the diphenylmethane diisocyanate isomer mixtures having a content of 4,4'-diphenylmethane diisocyanate greater than 96 weight percent, and in particular to the essentially pure 4,4'-diphenylmethane diisocyanate. Preferred polyhydroxy compounds having molecular weights of 500 to 8000 are the polyetherols, and in particular the polyesterols. However, it is also possible to use other hydroxyl-containing polymers containing ether or ester groups as connecting members, for example, polyacetals, such as polyoxymethylenes and in particular water-soluble formulas e.g. formal polybutanediol and formal poly-hexanediol and polycarbonate, in particular, those formed of diphenyl carbonate and 1,6-hexanediol prepared by transesterification. The polyhydroxy compound should at least be predominantly linear, i.e., difunctional within the meaning of the isocyanate reaction. The polyhydroxy compounds mentioned can be used as individual components or in the form of mixtures. Suitable polyetherols can be prepared from one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene residue, in a conventional manner, for example, by anionic polymerization with alkali metal hydroxides, such as sodium hydroxide. or potassium hydroxide, or the alkali metal alcoholates, such as sodium methoxide, sodium ethoxide, potassium ethoxide or potassium isopropoxide, as catalysts and in the presence of at least one initiator molecule containing from 2 to 3, preference 2 reactive hydrogen atoms, or by cationic polymerization with Lewis acids, such as antimony pentachloride, boron fluoride etherate, etc. or bleaching earth, as catalysts. Preferred alkylene oxides are, for example, tetrahydrofuran, 1,3-propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, and in particular ethylene oxide and 1,2-propylene oxide. The alkylene oxides can be used individually, alternatively in succession or as mixtures. Suitable initiator molecules are for example: water, organic dicarboxylic acids such as succinic acid, adipic acid and / or glutaric acid, alkanolamines such as ethanolamine, N-alkylalkanolamines, N-alkylalkanolamines, e.g. N-methyl and N-ethyl-diethanolamine, and preferably dihydric alcohols which may contain ether linkages, e.g. ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, 2-methyl-1, 5-pentanediol and 2-ethyl- 1,4-butanediol. The starter molecules can be used individually or as mixtures. Preference is given to the use of polyetherols of 1,2-propylene oxide and ethylene oxide wherein more than 50 percent, preferably 60 percent to 80 percent, or OH groups are primary hydroxyl groups and where at least some of the ethylene oxide units are present as a terminal block. These polyetherols can be obtained, for example, by polymerizing the initiator molecule first, the 1,2-propylene oxide, and then the ethylene oxide, or first all the 1,2-propylene oxide mixed with a certain amount of the ethylene oxide. and then the rest of the ethylene oxide or step by step first a certain amount of the ethylene oxide and then all the 1,2-propylene oxide and then the rest of the ethylene oxide. Other preferred possibilities with hydroxyl-containing tetrahydrofuran polymerization products.

Essentially linear polyetherols have molecular weights of 500 to 8000, preferably 600 to 6000, in particular 800 to 3500. The polyoxytetra ethylene glycols preferably have molecular weights of 500 to 2800. They can be used not only individually but also in the form of mixes one with the other. Suitable polyesterols can be prepared, for example, from dicarboxylic acids from 2 to 12, and preferably from 4 to 6 carbon atoms and the polyhydric alcohols. Suitable dicarboxylic alcohols are for example: aliphatic dicarboxylic acids, such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, and sebasic acid, and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid. The dicarboxylic acids can be used individually as mixtures, for example, in the form of a mixture of succinic acid, glutaric acid and adipic acid. To prepare the polyesterols it may be advantageous to use, instead of the dicarboxylic acids, the corresponding dicarboxylic acid derivatives such as dicarboxylic monoesters or diesters having from 1 to 4 carbon atoms in the alcohol residue, dicarboxylic anhydrides or dicarbonyl dichlorides. Examples of polyhydric alcohols are glycols of 2 to 10, preferably 2 to 6 carbon atoms such as ethylene glycol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, 2, 2-dimethylpropan-l, 3-diol, 1,3-propanediol and dipropylene glycol. Depending on the properties desired, the polyhydric alcohols can be used alone or optionally mixed with one another. It is also possible to use esters of carbonic acid with the mentioned diols, in particular those having from 4 to 6 carbon atoms such as 1-butanediol and / or 1,6-hexanediol, the condensation products of omega-hydroxycarboxylic acids , vg omega-hydroxycaproic acid and preferably the polymerization products of lactones, for example, substituted or unsubstituted omega-caprolactones. Preferred polyesterols are ethanediol polyadipates, 1,4-butanediol polyadipates, ethanediol / 1,4-butanediol polyadipates, 1,6-hexanediol / neopentyl glycol polyadipates, polyadipates and 1,6-hexanediol / polycaprolactones, 4- butanediol The polyesterols have molecular weights of 500 to 6000, preferably 800 to 3500. Suitable chain elongation agents having molecular weights of 60 to 400, preferably 60 to 300, are preferably aliphatic diols of 2 to 12 atoms carbon, preferably 2 to 4 or 6 carbon atoms, eg ethanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, and in particular 1, -butanediol. However, it is also possible to use diesters of terephthalic acid with glycols of 2 to 4 carbon atoms, e.g. bisethylene glycol terephthalate, 1,4-butanediol terephthalate and hydroxyalkylene hydroquinone ethers, e.g. 1, 4-bi (beta-hydroxyethyl) -hydroquinone, and also, polytetra ethylene glycols having molecular weights of 162 to 378. To adjust the hardness index, the forming components can be varied within relatively large molar ratios keeping in mind that the Hardness increases with the increased level of chain lengthening agents. To prepare relatively soft TPUs, which are especially preferred for use in the present invention, for example, those having a Shore A hardness of less than 90, it is advantageous to use the essentially difunctional polyhydroxy compounds (b) and the diols ( c) in a molar ratio of 1: 1 to 1: 4.5, preferably from 1: 5 to 2.4: 0 so that the resulting mixtures of (b) and (c) have an equivalent hydroxy weight greater than 200 , in particular from 239 to 450, as long as it is greater than 200, in particular from 239 to 450.

The catalysts suitable in particular for the reaction between the NCO groups of the diisocyanates (a) and the hydroxyl groups of the components (b) and (c) formers, are the customary tertiary amines such as triethylamine, dimethycyclohexylamine, N-methylmorpholine, N, '-dimethylpiperazine, diazabicyclo [2.2. -2] octane and the like, in particular organic metal compounds such as titanium esters, iron compounds, tin compounds, e.g. tin diacetate, tin dioctoate, tin dilaurate and dialkyltin salts of the aliphatic carboxylic acids such as dibutyltin diacetate, dibutyltin dilaurate and the like. The catalysts are used in a customary manner in amounts of 0.001 to 0.1 part by weight per 100 parts by weight of the mixture of the polyhydroxy compounds and the diols. In addition to the catalysts, the forming TPU components may also contain auxiliaries and / or additives. Examples are lubricants, inhibitors, hydrolysis stabilizers, flame retardants, colorants, pigments, inorganic and / or organic fillers or fillers and reinforcing agents. To prepare TPUs, the forming components, i.e., the diisocyanate compound, the polyhydroxy compound and one or more chain elongation agents are produced to react in the presence of a catalyst and in the presence or absence of auxiliaries and / or additives in amounts such that the ratio of the equivalence of the NCO groups of diisocyanate of hydroxyl groups of the polyhydroxy compounds and the chain elongation agent is from 0.95 to 1.10: 1, preferably from 0.98 to 1.08: 1. , in particular from 1.0 to 1.05: 1. TPUs which are usable in accordance with the present invention and which generally contain from 8 percent to 20 percent by weight, preferably from 8 percent to 16 percent by weight based on the total weight of urethane groups and have a melt flow index at 190 ° C under 21.6 kilograms from 1 to 500, preferably from 1 to 200, can be prepared by the extrusion apparatus technique or the belt technique by intermittent or continuous mixing of the components, by reacting the mixture in an extrusion apparatus or on a support belt at a temperature of 60 ° C to 250 ° C, preferably 70 ° C to 150 ° C and then granulating the resulting TPU. The technique of the reactor extrusion apparatus, as is well known in the art, is especially preferred. It may be advantageous to heat the resulting TPU to a temperature of 80 ° C to 120 ° C, preferably 100 ° C to 110 ° C for a period of 1 to 24 hours before further processing. One or more of the acrylate-based rubbers of the composition usually comprises a terpolymer. An example of an illustrative commercially obtainable material is Sunigum® from Goodyear Chemicals1. They can use one or more UV stabilizers as additives that will preferentially absorb and dissipate the energy by releasing the excited molecules from the excess energy and releasing it as heat. Generally, preferred stabilizers for use herein will be effective within the range of 300 to 360 nanometers. An example of suitable ultraviolet and thermal stabilizers are the o-hydroxybenzophenone derivatives, o-hydroxyphenyl salicylates, 2- (o-hydroxyphenyl) -benzotriazoles and hindered phenols. It has been found in particular, the ultraviolet ray stabilizing compositions of the claimed invention surprisingly confer thermal stability without the opacification and yellowing found in many of the UV stabilized compositions of the prior art. 1 Sunigum® is a registered trademark of Goodyear Chemical.

The hindered amine light stabilizers are also suitable for use herein as ultraviolet stabilizers. Ultraviolet ray stabilizers are those that have active ingredients that are stabilizers of spherically hindered benzotriazole type. It will be appreciated that many ultraviolet stabilizers with concentrates containing other materials in addition to the active ingredient. The active ingredients, particularly preferred for use as the ultraviolet ray stabilizers are 2- (2-hydroxy-3,5-di-tert-amylphenyl) -2H-benzotriazole, propionate of 1,6-hexanediylbis (3-benzotriazole-N) -yl) -4-hydroxy-5-tert-butyl) phenyl and mixtures thereof. In particular, one or more of the especially preferred ultraviolet ray stabilizers for use in the present invention will be the stabilizer concentrates containing the above-mentioned especially preferred active ingredients. These stabilizer concentrates will preferably also contain thermoplastic polyurethanes (TPU) and 1,3,5-triglycidyl isocyanurate. These concentrates of the ultraviolet ray stabilizer are discussed in Patent Number DE 4211335 A, the disclosure of which is incorporated herein by reference. Especially preferred ultraviolet stabilizer concentrates will contain from about 40 percent to 80 weight percent thermoplastic polyurethanes, from 10 percent to 30 percent by weight of 1, 3, 5-triglycidyl-isocyanurate, and from 10 percent at 30 weight percent 2- (2-hydroxy-3,5-di-tert-amyl-phenyl) -2H-benzotriazole, 1,6-hexanediylbis (3-benzotriazole-N-yl) -4- propionate hydroxy-5-tert-butyl) phenyl and mixtures thereof. In addition, the thermoplastic polyurethane compositions of the invention optionally also contain one or more compatibilizing polymers. These compatibilizing polymers generally comprise copolymers formed of styrene, alpha-methylstyrene, acrylonitrile, methacrylonitrile, butadiene, acrylate and mixtures thereof. Preferred compatibilizers are poly (styrene-acrylonitrile) and ABS. Poly (styrene-acrylonitrile) is especially preferred. Finally, the thermoplastic polyurethane compositions of the invention may optionally also contain additives that are selected from the group consisting of lubricants, inhibitors, anti-hydrolysis stabilizers, fire retardant agents, colorants, pigments, inorganic and / or organic fillers or fillers, and reinforcing agents. Particularly preferred additives are dyes and pigments.

Titanium dioxide is a commonly used pigment. Of course, those skilled in the art will appreciate that the incorporation of these dyes and pigments depends on the desired appearance of the end-use application. With respect to the aforementioned components of the thermoplastic polyurethane compositions of the invention, these compositions preferably contain from 50 percent to 100 percent of one or more thermoplastic polyurethanes, from more than 10 percent to 40 percent of one or more more acrylate-based rubbers, and from 0.1 percent to 5.0 percent of active ingredients of one or more of the UV stabilizers as they are based on the total combined weight of the components. More preferably, the thermoplastic polyurethane compositions of the invention will contain from 60 percent to 80 percent of one or more thermoplastic polyurethanes, from more than 20 percent to 40 percent of one or more acrylate-based rubbers and 1 percent to 4 percent of the active ingredient of one or more UV stabilizers, as they are based on the total combined weight of the components. If the thermoplastic polyurethane composition of the invention also comprises a compatibilization polymer, this polymer must be present in an amount of 1 percent to 10 percent, as it is based on the total weight of the combined components. More preferably, the thermoplastic polyurethane composition comprising a compatibilizing polymer will contain less than 5 percent of the polymer and most preferably will comprise from 2 percent to 4 percent of the compatibilizing polymer. It will be appreciated that additives will be present in amounts that depend on the desired final properties of the composition. It will be appreciated that in the present invention, the thermoplastic polyurethane composition is a mixture wherein the predominant matrix consists of thermoplastic polyurethane. Scattered in that matrix, there are particles of one or more acrylate-based rubbers. If present, the compatibilizing polymer will serve as the interface between the acrylate-based rubber particles and the TPU matrix. Ultraviolet stabilizers will also be interdispersed within the TPU of the matrix.

Claims (14)

R E I V I N D I C A C I O N E S:

1. A thermoplastic polyurethane composition comprising: a) from 3 to 200 parts of a styrene / alpha-methylstyrene / acrylonitrile / alkyl acrylate terpolymer of 1 to 6 carbon atoms with a lower glass transition temperature (Tg) 0 ° C; and b) 100 parts of a thermoplastic polyurethane produced from a diisocyanate, a diol having from 2 to 10 carbon atoms, and a polyol based on polyether and / or polyester; wherein the thermoplastic polyurethane blend has a Shore A hardness of less than or equal to 90.

2. The thermoplastic polyurethane composition of claim 1, further comprising one or more compatibilizing polymers.

3. The thermoplastic polyurethane composition of claim 1, wherein the thermoplastic polyurethane composition is prepared using polyhydroxy compounds which are selected from the group consisting of polyetherols and polyesterols.

4. The thermoplastic polyurethane composition of claim 3, wherein the thermoplastic polyurethane composition is prepared using polyetherols.

5. The thermoplastic polyurethane composition of claim 1, wherein the thermoplastic polyurethane composition is prepared using aromatic isocyanates.

6. The thermoplastic polyurethane composition of claim 1, wherein the thermoplastic polyurethane composition is prepared using diphenylmethane diisocyanate. The thermoplastic polyurethane composition of claim 1, wherein the acrylate terpolymer has a Tg less than 0 degrees centigrade. The thermoplastic polyurethane composition of claim 7, wherein the acrylate terpolymer has from 40 percent to 85 percent alkyl acrylate of 1 to 6 carbon atoms. The thermoplastic polyurethane composition of claim 1, further comprising an ultraviolet ray stabilizer consisting of one or more materials having an active ingredient that is selected from the group consisting of benzotriazole type stabilizers and type stabilizers. phenol prevented. The thermoplastic polyurethane composition of claim 9, wherein the ultraviolet ray stabilizer comprises an active ingredient that is selected from the group consisting of 2- (2-hydroxy-3,5-di-ter-amyl-phenyl) -2H-benzotriazole, propionate of 1,6-hexanediylbis (3-benzotriazol-N-yl) -4-hydroxy-5-tert-butyl) phenyl and mixtures thereof. The thermoplastic polyurethane composition of claim 2, wherein the composition comprises from 1 percent to 10 percent of a compatibilizing polymer, as based on the total weight of the components in the thermoplastic polyurethane composition. The thermoplastic polyurethane composition of claim 11, wherein the composition comprises less than 5 percent of a compatibilizing polymer as based on the total weight of the components of the thermoplastic polyurethane composition. The thermoplastic polyurethane composition of claim 12, wherein the composition comprises from 2 percent to 4 percent of a compatibilizing polymer as based on the total weight of the components in the thermoplastic polyurethane composition. 14. The thermoplastic polyurethane composition of claim 2, wherein the compatibilizing polymer is an acrylonitrile / styrene copolymer.