A reactive injection molding resinous composition

Abstract: A reactive injection moulding resinous composition comprise a polyamine component and a polyisocyanate component, in which: the polyamine component comprises: (1) a polyoxyalkylene polyamine having an average molecular weight of 1,000 to 10,000 and containing 2 or more aliphatic amino groups in its molecule; (2) a polyoxyalkylene polyamine product (A) obtained by mixing (i) a polyoxyalkylene polyepoxy compound having an average molecular weight of 1,000 to 10,000 and containing 2 or more epoxy groups in its molecule and (ii) an aromatic diamine having a molecular weight of 108 to 400, so that the equivalents of amino groups are in excess of the equivalents of epoxy groups, and reacting the mixture; (3) a polyoxyalkylene polyamine product (B) obtained by mixing (iii) a polyoxyalkylene polyepoxy compound having an average molecular weight of 270 to 1,000 and containing more than 2 epoxy groups in its molecule and (ii) an aromatic diamine having a molecular weight of 108 to 400, so that the equivalent of amino groups are in excess the equivalents of epoxy groups, and reacting the mixture; and (4) an aromatic diamine (as a chain extender) having an average molecular weight of 122 to 400 and having at least one alkyl or thioalkyl substituent at ortho to a respective amino group; and (I) the polyisocyanate component comprises: (5) an aromatic polyisocyanate compound having an average molecular weight of 174 to 1,500 and containing 2 or more isocyanate groups in its molecule; (6) an aliphatic polyisocyanate compound having an average molecular weight of 158 to 1,500 and containing 2 or more isocyanate groups; and (7) a liquid polyisocyanate prepolymer product obtained by mixing an aromatic or aliphatic polyisocyanate compound having an average molecular weight of 158 to 1,500 and containing 2 or more isocyanate groups in its molecule with a liquid polydiene compound having an average molecular weight of 1,000 to 5,000 and containing in its molecule 2 or more reactive functional groups selected by hydroxyl, amino, carboxyl and epoxy groups, so that the isocyanate groups are in excess of the reactive functional groups, and reacting the mixture.

Description: The present invention relates to a reactive injection molding resinous composition and more specifically, it concerns a resinous composition which is excellent in molding properties and is capable of resulting in an injection-molded polyurethane product having both excellent heat resistance and impact strength. Recently, production of urethane bumpers or the like in a mold by means of reactive injection molding is being watched with keen interest and various proposals have been made as stated, for example, in US-A-4,254,069: US-A-3,838,076, US-A-4,216,543: US-A-4,246,363: and US-A-4,269,945. In this area, a specifically attractive one is the method of Japanese Patent Publication (unexamined) 188643/83, wherein a mixture of end-amine bearing polyether having an average molecular weight of 1,500 or more, end-amine bearing chain extender and polyisocyanate is reacted in a closed mold to give an elastic injection-molding which is excellent in mechanical strength, heat resistance and other desired properties. Similarly, EP-A-0278334 discloses compositions for producing polyurethanes and comprising polyisocyanate, together with, as reactive components the reaction product of a polyepoxide and an excess of diamine. Recently, as an automobile decorative material, various plastics have been examined and some are actually used in certain areas. Since a polyurethane molding obtained by the reaction of polyalkylene polyol and polyisocyanate in a mold has many problems such that polyurethane is rather poor in heat resistance, is expensive and has certain limits in its coating, public interests are prone to move, from polyurethane/polyurea, to polyurea which has excellent heat resistance. However, reaction speed between end-amine bearing polyether and polyisocyanate is much higher than the reaction speed between polyether polyol and polyisocyanate, and therefore, in the case of such polyurea molding, the reaction mixture must be filled in a mold within a very short period of time, say 1 second or less. This, in turn, may give rise to certain difficulties in both respects of apparatus and materials to be used. That is, there are problems of efficient control in the optimum speed and in the viscosity of the injected material. The principal object of substituting polyurea for polyurethane for use as an automobile exterior panel is to simplify the automobile production line by enabling the simultaneous application and then baking of baking enamel on the assembly for both steel and plastic components. Therefore, such molding should preferably withstand well thermal deformation at the baking temperature in an electro-deposition coating line. However, polyurea materials with excellent heat resistance properties tend to be more brittle than polyurethane, and therefore, have lower impact resistance. Therefore, an essential feature of the work is the development of new reactive injection molding resinous composition that will give both excellent heat resistance and impact resistance. Summary of the Invention According to the present invention, the abovementioned object can be attained with a reactive injection molding resinous composition comprising a polyamine component and a polyisocyanate component, in which: the polyamine component comprises: (1) a polyoxyalkylene polyamine of the formula R(NH₂) n , in which R is polyoxyalkylene and n is an integer of two or more, and having an average molecular weight of 1,000 to 10,000; (2) a polyoxyalkylene polyamine (A) obtained by reacting (i) a polyoxyalkylene polyepoxy compound having a number average molecular weight of more than 1,000 to 10,000 and containing 2 or more epoxy groups in its molecule and (ii) an aromatic diamine having a molecular weight of 108 to 400, in relative amounts such that the equivalents of amino groups are in excess of the equivalents of epoxy groups; (3) a polyoxyalkylene polyamine (B), obtained by reacting (iii) a polyoxyalkylene polyepoxy compound having a number average molecular weight of 270 to less than 1,000 and containing more than 2 epoxy groups in its molecule and (ii) an aromatic diamine having a molecular weight of 108 to 400, in relative amounts such that the equivalent of amino groups are in excess of the equivalents of epoxy groups; and (4) an aromatic diamine (as a chain extender) having an average molecular weight of 122 to 400 and having at least one alkyl or thioalkyl substituent at ortho to a respective amino group; and the polyisocyanate component comprises: (5) an aromatic polyisocyanate compound having an average molecular weight of 174 to 1,500 and containing 2 or more isocyanate groups in its molecule; (6) an aliphatic polyisocyanate compound having an average molecular weight of 158 to 1,500 and containing 2 or more isocyanate groups; and (7) a liquid polyisocyanate prepolymer obtained by reacting an aromatic or aliphatic polyisocyanate compound having an average molecular weight of 158 to 1,500 and containing 2 or more isocyanate groups in its molecule with a liquid polydiene compound having an average molecular weight of 1,000 to 5,000 and containing in its molecule 2 or more reactive functional groups selected by hydroxyl, amino, carboxyl and epoxy groups, in relative amounts such that the isocyanate groups are in excess of the reactive functional groups; the ratio of the average amino equivalent of polyamine components (1) to (4) to the average isocyanate equivalent of polyisocyanate components (5) to (7) being from 1:0.7 to 1:1.5; and wherein the aliphatic polyisocyanate compound (6) forms at most 20% by weight of the total polyisocyanate component. The polyamine components used in the present reactive injection molding resinous composition are composed of the above-mentioned 4 groups. The first group of polyamine component is a polyoxy alkylene polyamine (1) represented by the formula: R(NH₂) n in which R is polyoxyalkylene and n in an integer of 2 or more, which is advantageously obtained by effecting amination of end hydroxyl groups of polyoxyalkylene polyol having an average molecular weight of 1,000 to 10,000. The polyoxyalkylene polyol used as the starting material may be advantageously prepared by effecting ring polymerization of an alkylene oxide on an active hydrogen containing compound by a conventional means. As the active hydrogen containing compounds, mentions are given to the compounds bearing such groups as hydroxyl, carboxyl, amine, hydrazine, imine, amide, guanidine, sulfonamide, urea, thiourea, mercapto, thiophenol and thiocarboxyl groups. Examples of such compounds are diols such as ethyleneglycol, 1,2-propyleneglycol, 1,3-propyleneglycol, 1,3-butanediol, 1,4-butanediol, 1,2-butanediol, 2,3-butanediol, 3-chloro-1,2-propyleneglycol, 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 1,2-octanediol, 1,3-octanediol, 1,4-octanediol, 1,6-octanediol, 1,8-octanediol, 1,10-decanediol and the like; triols such as glycerin, 1,2,6-hexanetriol, 1,1,1-trimethylolethane and 1,1,1-trimethylol propane; polyols such as erythritol, pentaerythritol, pentite, sorbitol, xylite, arabibite and mannitol; trialkanolamines such as triethanolamine, triisopropanolamine and tributanolamine; amines such as methylamine, ethylamine, isopropylamine, butylamine, benzylamine, aniline, toluidine, naphthylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, 1,3-butanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,2-hexanediamine, 1,3-hexanediamine, 1,4-hexanediamine, 1,5-hexanediamine, 1,6-hexanediamine, phenylenediamine, toluenediamine and naphthalenediamine; toluenediamines; nonreducing sugar or derivatives thereof such as cane sugar, alkylglucoside (ethylglucoside and the like), glycolglucosides (e.g. ethyleneglycolglucoside, propyleneglycolglucoside, glyceringlucoside and 1,2,6-hexanetriolglucoside); polyphenols such as 2,2-bis (4-hydroxyphenyl propane, bis (4-hydroxyphenyl) methane, condensation products of phenol and formaldehyde, novolak resin, condensation products of phenolic compound and acrolein (e.g. 1,1,3-tris (hydroxyphenyl) propane), condensation products of phenolic compound and glyoxal, glutaraldehyde or other dialdehyde (e.g. 1,1,2,2-tetrakis (hydroxyphenyl) ethane); condensation products of aromatic amines such as aniline and toluidine, phenols such as phenol, cresol and the like, and aldehydes such as formaldehyde; phosphoric acids such as phosphoric acid, phosphorous acid, polyphosphoric acid (e.g. tripolyphosphoric acid and polymethaphosphoric acid); polytetramethyleneglycol; glycerides such as castor oil and halogenides thereof. One or more of the above-mentioned compounds may satisfactorily be used. Amongst them, particular preference is given to one or more of the members selected from glycerin, trimethylolpropane, pentaerythritol, sorbitol, ethylenediamine, diethylenetriamine, cane sugar and 2,2-bis (4-hydroxyphenyl) propane. The most preferable members are glycerin, trimethylol propane, pentaerythritol, mixtures of cane sugar and glycerin and ethylenediamine. The second group of polyamine component is a polyoxy alkylene polyamine product (A) obtained by reacting an excess amount of specific aromatic diamine (ii) with a specific polyoxy alkylene polyepoxy compound (i). Such polyoxyalkylene polyepoxy compound (i) can be obtained by effecting epoxidation of polyoxyalkylene polyol (stated in for example, Japanese Patent Publication (unexamined) 31513/78, Brit Patent 1286676 and US Patent 3,445,525 with epichlorohydrin, the compound (i) having a number average molecular weight of about 1,000 to 10,000 and containing in its molecule 2 or more epoxy groups. Various polyepoxy compounds belonging to this class have been marketed, as, for example, DENACOL EX-2000 (polyoxypropylene glycol diglycidyl ether, epoxy equivalent about 1,100g, trade mark of Nagase Kasei Kogyo K.K.) and DENACOL EX-400 (polyoxypropylene glycol diglycidyl ether, epoxy equivalent about 2,270g, trade mark of Nagase Kasei Kogyo K.K.). Examples of the aromatic diamines (ii) are 1-methyl-3,5-dimethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, 1,3,5-triethyl-2,6-diaminobenzene, 3,5,3',5'-tetraethyl-4,4'-diaminodiphenylmethane, 3,5-diethylthio-2,4-toluenediamine and 3,5-dimethylthio-2,6-toluenediamine. Particularly preferable diamine compounds are 1-methyl-3,5-diethyl-2,6-diaminobenzene, 1-methyl-3.5-diethyl-2,4-diaminobenzene and mixtures thereof. The molecular weights of these diamines are in the range of 108 to 400. The abovementioned polyoxyalkylene polyepoxy compounds and aromatic diamines are reacted in such ratios that amino groups in excess of epoxy groups in terms of equivalent amounts and therefore, the reaction product includes, besides the desired polyoxyalkylene polyamine (2), certain amounts of unreacted aromatic diamines. The third group of polyamine components is a polyoxyalkylene polyamine product (B) obtained by the reaction of excess amounts of particular aromatic diamines (ii) and particular polyoxyalkylene polyepoxy compounds (iii). The polyoxyalkylene polyepoxy compound (iii) should have a number average molecular weight of about 270-1,000, preferably 270-500, and contain in its molecule more than 2 epoxy groups. Such compounds (iii) may be obtained by effecting epoxidation of end groups of polyoxyalkylene polyol compounds with epichlorohydrin as disclosed in, for example, Japanese Patent Publication (unexamined) 31513/78; GB 1,286,676; and US Patent 3,445,525. Various products are available in the market such as DENACOL EX-321 (trimethylol propane polyglycidyl ether, epoxy equivalent about 145, trademark, Nagase Kasei Kogyo K.K.), DENACOL EX-411 (pentaerythritol polyglycidyl ether, epoxy equivalent about 231, trademark of Nagase Kasei Kogyo K.K.), and DENACOL EX-301 [triglycidyl tris (2-hydroxyethyl) isocyanurate, epoxy equivalent about 242, trademark of Nagase Kasei Kogyo K.K.], and all of these products are successfully and advantageously used in the present invention. Examples of the aromatic diamine (ii) are 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene (both of them may sometimes be called diethyltoluene diamine or DETDA), 1,3,5-triethyl-2,6-diaminobenzene, 3,5,3',5'-tetraethyl-4,4'-diaminodiphenyl methane, 3,5-diethyl thio-2,4-toluenediamine and 3,5-dimethyl thio-2,6-toluenediamine, and include the same members as stated herein before. Particularly preferable members are 1-methyl-3,5-diethyl-2,6-diaminobenzene, 1-methyl-3,5-diehtyl-2,4-diaminobenzene or mixtures thereof. These diamines have an average molecular weight of 108-400. The abovementioned polyoxyalkylene polyepoxy compounds and diamines are reacted with each other in such weight ratios that amino groups become in excess of epoxy groups in terms of equivalent amount and therefore, the resulted product includes, besides the desired main product of polyoxyalkylene polyamine (3), certain amounts of unreacted aromatic diamines used. In this invention, as the forth polyamine component and as a chain extender, is used an aromatic diamine (4) having at least one alkyl or thioalkyl substituent at the ortho position of the respective amino group. Examples of such aromatic diamines are 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diehtyl-2,6-diaminobenzene (both of them are sometimes called diethyltoluene diamine or DETDA), 1,3,5-triethyl-2,6-diaminobenzene, 3,5,3',5'-tetraethyl-4,4'-diaminodiphenylmethane, 3,5-diethyl thio-2,4-toluenediamine and 3.5-dimethyl thio-2,6-toluenediamine Particularly preferred members are 1-methyl-3,5-diethyl-2,6-diaminobenzene, 1-methyl-3,5-diethyl-2,4-diaminobenzene or mixtures thereof. In this invention, the following three polyisocyanates are used as the hardening component for the abovementioned (1)-(4) polyamines. The first group of polyisocyanates is an aromatic polyisocyanate compound (5) customarily used in the preparation of polyurea or polyurethane resin, i.e. an aromatic polyisocyanate having in its molecule 2 or more isocyanate groups and having an average molecular weight of 174-1,500. Typical examples are p-phenylene diisocyanate, polymethylene polyphenyl isocyanate, 2,6-toluenediisocyanate, dianisidine diisocyanate, bitolylene diisocyanate, naphthalene-1,4-diisocyanate, bis (4-isocyanate phenyl) methane, bis (3-methyl-3-isocyanatephenyl) methane and 4,4'-diphenylpropane diisocyanate. Particularly preferred members are methylene bis (4-phenyl isocyanate) in the form of pure MDI, MDI prepolymer or modified MDI. The second group of polyisocyanates is an aliphatic polyisocyanate compound (6) having an average molecular weight of 158-1,500 and containing 2 or more isocyanate groups. Typical examples are dicyclohexyl methane-4,4'-diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, their isocyanurated derivatives and their carbodimidized modified products. Particularly preferred aliphatic polyisocyanates are pure hexamethylene diisocyanate, hexamethylene diisocyanate perpolymer and modified hexamethylene diisocyanate. The other group of the polyisocyanate component is a liquid polyisocyanate prepolymer product (7) obtained by mixing and reacting an aromatic or aliphatic polyisocyanate compound having an average molecular weight of 158-1,500 and containing in its molecule 2 or more isocyanate groups and a liquid polydiene compound having an average molecular weight of 1,000-5,000 and containing in its molecule 2 or more reactive functional groups selected from hydroxyl, amino, carboxyl and epoxy groups so that isocyanate groups become in excess of the said reactive functional groups. The polyisocyanate compound to be pre-reacted with the said polydiene compound may be any members selected from liquid organic polyisocyanates customarily used for the preparation of polyurethane or polyurea or isocyanate prepolymers obtained by the partial reaction of organic polyisocyanates and polyether polyols or polyamines, providing there is contained in the molecule 2 or more isocyanate groups having an average molecular weight of 158-1,500, preferably 158-500. Examples of aromatic polyisocyanates are p-phenylene diisocyanate, polymethylene polyphenylisocyanate, 2,6-toluene diisocyanate, dianisidine diisocyanate, bitolylene diisocyanate, naphthalene-1,4-diisocyanate, bis (4-isocyanate phenyl) methane, bis (3-methyl-3 isocyanate phenyl) methane and 4,4'-diphenyl propane diisocyanate. Examples of aliphatic polyisocyanates are dicyclohexyl methane-4,4'-diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, and their isocyanurated derivatives and carbodiimidized modified products. Particularly preferred members are such aromatic polyisocyanates such as the pure MDI form of methylene bis (4-phenyl isocyanate), MDI, MDI prepolymer and modified pure MDI, and such aliphatic polyisocyanates as pure hexamethylene diisocyanate, hexamethylene diisocyanate prepolymer and modified hexamethylene diisocyanate. The liquid polydiene compound having at the both ends NCO-reactive functional groups, to be reacted with the abovementioned polyisocyanate for the preparation of polyisocyanate prepolymer (7), should have an average molecular weight of 1,000-5,000. Many compounds coming under this category have been known and we available in the market, including polybutadiene R45-HT (trademark of Idemitsu Ahko K.K., ω -polybutadieneglycol, average molecular weight about 2,800, OH equivalent about 1,220g), Nisso PBG-1000 (trademark of Nihon Soda K.K., α,ω -polybutadieneglycol, average molecular weight about 1,350 OH equivalent about 742g) and Highcar CTBN 1,300x31 (trademark of Ube Kosan K.K., α,ω -dicarboxylpolybutadiene-acrylonitrile copolymer, average molecular weight about 3,500, bound AN 17%, COOH equivalent 1,822g, average functional group number 1,9/mol). Other examples are polyolefinic polyols such as Epol (trademark of Idemitsu Sekiyu Chem. Co., hydrogenated polyisopreneglycol, average molecular weight about 2,500, OH equivalent about 1,110) and hydrogenated polybutadiene resin such as, for example, Nisso PB-GI-1000 (trademark of Nihon Soda K.K.) and various modified products thereof. The abovementioned polyisocyanate and liquid polybutadiene are reacted so that isocyanate groups are in excess, preferably 2 times or more and most preferably 5 times or more excess, of NCO-reactive functional groups in terms of equivalent amount. Thus formed polyisocyanate prepolymer may, therefore, contain, besides the reaction product of polyisocyanate-polybutadiene-polyisocyanate, an excess amount of polyisocyanate compound used as the starting material. The principal object of this invention is to provide a resinous composition for injection molding use which is excellent in molding properties and capable of resulting in a polyurea injection-molded product being excellent in both thermal resistance and impact strength at low temperatures. To attain the abovementioned object, the inventors have found the following are very important for in the practical point of view. (1) Equivalent amount ratios of average amino groups of polyamine components (1)-(4) to average isocyanate groups of polyisocyanate components (5)-(7) should be 1:0.7 - 1: 1.5, preferably 1:0.95 - 1:1.25 and most preferably 1:1.01 - 1:1.10. (2) In order to obtain a cured product which is well resistive to cracking in a mold and excellent in thermal resistance, the content of polyoxyalkylene polyamine included in the polyoxyalkylene polyamine product (B) should preferably be in a range of 3.0-10.0 weight % of the total weight of the composition. (3) To attain a cured product which is particularly excellent in impact strength, the polydiene chain content included in (7) should preferably be at least 6.5% by weight of the total resin weight and the aromatic ring content included in (1)-(7) should preferably be at most 40% by weight of the total resin weight. (4) In order to obtain a cured product which is particularly excellent in thermal resistance, the aromatic ring content included in (1)-(7) should preferably be at least 30% by weight of the total resin weight and the polyoxyalkylene polyamine content included in (3) be at least 3.0% by weight of the total resin weight. (5) To secure an appropriate flowability of the composition, it is desired to increase the amounts of (1) and (4) among the polyamine components (1)-(4). However, with the increase in the amount of component (4), there is an accompanying increase in aromatic ring content in the total system, resulting in an undesired decrease in impact strength of the molded product. Therefore, under the circumstances, it is preferred to increase the amount of polyoxyalkylene polyamine (1) having aliphatic amino groups as high an amount as possible. However, this always gives the additional problem that when subjected to injection molding, the curing speed, i.e. reaction speed of the mixture of polyamine components and polyisocyanate components, will become too high, giving an undesired decrease in mold-filling properties of the composition. The polyamine component (1) may be increased up to 50% by weight of the total polyamine components (1)-(4), but from the standpoint of thermal resistance of the molded product, it should preferably be 30% or less of the total polyamine components. (6) In order to control the curing speed at the time of injection molding within an appropriate range, it is highly recommended to use an appropriate amount of aliphatic polyisocyanate (6) and isocyanate component. To lower the curing speed, the amount of aliphatic polyisocyanate should preferably be increased as high as possible among the polyisocyanate components (5)-(7). However, to adjust the aromatic ring content at the desired level for the attainment of appropriate curing and heat resistant properties, the aliphatic polyisocyanate component (6) should be at most 20% by weight of the total polyisocyanate components. The present resinous composition comprises particular polyamine components and polyisocyanate components. Since the curing is achieved at comparatively slow speed, the present composition is characterized by having a considerably long flowability retention time, as long as 1.3 seconds or more, and hence, workability and molding properties are greatly improved compared with the conventional polyurea composition. At the stage of impingement-mixing of the principal component and hardener component and curing of the thus obtained mixture, there occurs phase separation due to the poor compatibility. In this invention, making use of the abovementioned phenomenon, it is possible to obtain an elastomeric product having sea-and-island structures, the said sea being mainly composed of polyurea components and the islands being mainly composed of polydiene components, characterized by having improved heat distortion resistance at higher temperatures and improved impact resistance at lower temperatures. For the actual use of the present resinous composition in a reactive injection molding, other additives such as surfactant, foam stabilizer, fire-retardant, plasticizer, dyestuff, filler, fungicide, bactericide, various reinforcing materials and inner mold release agent may be advantageously used as desired. Thus, the present resinous composition has an improved workability and molding property as an injection molding material, and can result in an injection-molded product which is free from the disadvantages possessed by the heretofore known injection-molded products and is excellent in thermal resistance. Therefore, the injection-molded products can be advantageously applied with a common, baking-type coating composition and hence, the present composition is specifically useful in the automobile and other industries. The invention shall be now more fully explained in the following Examples. In this specification and claims, the term "aromatic ring content in the total weight of the cured resin" shall mean the ratio of total aromatic ring weight/total weight of polyamine and polyisocyanate, the aromatic ring weight being the weight of benzene ring and hydrogen atoms directly bonded there to. The polydiene chain content in the cured resin shall mean the ratio of total polydiene chain weight/total weight of the cured resin, providing taking the diene series compound, which is still unmodified with isocyanate compound, as a polydiene chain. The polyoxyalkylene polyamine content in the polyamine product (B) is defined, in this specification, as being equal to the difference between the polyoxyalkylene polyamine product (B) and the remaining aromatic diamine used. Manufacturing Examples 1-3 Preparation of liquid polyisocyanate: α,ω-polybutadieneglycol (polybutadiene R45-HT) and diphenylmethane diisocyanate (Millionate MTL, Nippon Polyurethane Kogyo K.K. NCO equivalent about 145 g) were reacted in a weight ratio of 50:50 (equivalent ratio of OH groups : isocyanate groups of 1:8.4), at 80°C for 3 hours to obtain a liquid polyisocyanate (a) (viscosity 10,000 cps, 25°C). Hydrogenated polyisopreneglycol (Epol) and diphenyl methanediisocyanate (Millionate MTL) were reacted, in a weight ratio of 25:100 (equivalent ratio of OH groups : NCO groups of 1:30), at 80°C for 3 hours to obtain a liquid polyisocyanate (b) (viscosity 200 cps, 25°C). Separately, α,ω-polybutadieneglycol (polybutadiene R45-HT) and hexamethylene diisocyanate (HDI, Nippon Polyurethane Kogyo K.K., NCO equivalent = about 84 g) were mixed in a weight ratio of 290:100 (equivalent ratio of OH groups : NCO groups of 1:5) and reacted at 80°C for 3 hours to obtain a liquid polyisocyanate (c) (viscosity 6,000 cps, 25°C). Manufacturing Examples 4-8 Preparation of polyoxyalkylene polyamines: Polyoxyprophleneglycol diglycidylether (DENACOL EX-2000) and diethyltoluenediamine (Ethacure 100, Ethyl Corp.) were reacted, in a weight ratio of 1,100:360 (equivalent ratio of epoxy groups : amine active hydrogen of 1:8), at 140°C for 6 hours to obtain a polyoxyalkylene polyamine (1) (Sample No. 1) (viscosity 3,100 cps, 25°C). Various polyoxyalkylene polyamines (Sample No. 2 to 5)were prepared in the same way, using the epoxy compounds and diamine compounds shown in Table 2. Example 1 Polyamine mixture (A) consisting of 20 parts by weight of Jeffermine D-2000, 25 parts by weight of polyamine sample (1), 50 parts by weight of polyamine sample (3) and 5 parts by weight of Ethacure 100, and polyisocyanate mixture (B) consisting of 51 parts by weight of Millionate MTL, 15 parts by weight of Coronate EH and 70 parts by weight of polyisocyanate sample (a) were, while impingement-mixing in a weight ratio of A:B of 100:136, placed into a mold and subjected to an injection-molding under the following conditions: mold size length 400mm width 300mm thickness 3mm material temperature 57±2°C injection pressure 150±20 kg/cm² injection speed about 330 cc/sec. mold temperature 120±2°C After elapsing 1 minute, the molded product was taken out the mold and cured at 140°C±2°C for 30 minutes Properties of the thus obtained product were evaluated, following the test methods hereinafter stated, and the test results were shown in Table 3. Examples 2-8 and Comparative Examples 1-7 Using the materials shown in Table 3 and following the procedures stated in Example 1, various injection-molded products were prepared and evaluated as in Example 1. Test results are shown in Table 3. Evaluation methods 1. Molding property-1 Mold filling property of resinous composition was evaluated with the following standards. ○ keep and adequate flowability capable of being filled in a mold for 1.3 seconds counting from the start of material filling X substantial loss of flowability within 1.3 seconds from the start of material filling, resulting in the failure of adequate filling in a mold. 2. Molding property-2 Resinous composition was placed in a mold and subjected to an injection-molding. After elapsing 1 minute, the injection molded product was taken out the mold and the presence of cracks in the molded product was examined. ○ no cracks X cracks 3. Flowability Viscosity of polyamine component and polyisocyanate component each was measured by using BH-type viscometer (Tokyo Keiki K.K.) ○ less than 3,500 cps at 25°C X 3,500 cps or more at 25°C 4. Heat-sag resistance Heat resistance test was carried out following ASTM D 3,769 excepting changing over-hang length to 152mm and test temperature to 190°C. ○ less than 6mm of heat-sagging value ▵ 6mm or more, but less than 10mm X 10mm or more 5. Impact strength test Apparatus of JIS K 5400 (Impact resistance test method B) was used. Test specimen was cut from the molded resin plate (about 100x100x3mm). Impact deformation tester was horizontally fixed on a concrete rest, to which a hammer die having a radius of 6.35± 0.03mm and a receptacle were secured. A test specimen previously cooled to -30°C was placed between the hammer die and the receptacle, and a weight (about 1kg weight) was also used to fall, from the height of about 40cm, on said hammer die. Then, the test specimen was carefully taken out and the presence of cracks was examined. ○ no cracks ▵ cracks, but maintain the original form of test specimen X crush out

Claims: A reactive injection moulding resinous composition comprising a polyamine component and a polyisocyanate component, in which: the polyamine component comprises: (1) a polyoxyalkylene polyamine of the formula R(NH₂) n , in which R is polyoxyalkylene and n is an integer of two or more, and having an average molecular weight of 1,000 to 10,000; (2) a polyoxyalkylene polyamine (A) obtained by reacting (i) a polyoxyalkylene polyepoxy compound having a number average molecular weight of more than 1,000 to 10,000 and containing 2 or more epoxy groups in its molecule and (ii) an aromatic diamine having a molecular weight of 108 to 400, in relative amounts such that the equivalents of amino groups are in excess of the equivalents of epoxy groups; (3) a polyoxyalkylene polyamine (B), obtained by reacting (iii) a polyoxyalkylene polyepoxy compound having a number average molecular weight of 270 to less than 1,000 and containing more than 2 epoxy groups in its molecule and (ii) an aromatic diamine having a molecular weight of 108 to 400, in relative amounts such that the equivalent of amino groups are in excess of the equivalents of epoxy groups; and (4) an aromatic diamine, as a chain extender, having an average molecular weight of 122 to 400 and having at least one alkyl or thioalkyl substituent at ortho to a respective amino group; and the polyisocyanate component comprises: (5) an aromatic polyisocyanate compound having an average molecular weight of 174 to 1,500 and containing 2 or more isocyanate groups in its molecule; (6) an aliphatic polyisocyanate compound having an average molecular weight of 158 to 1,500 and containing 2 or more isocyanate groups; and (7) a liquid polyisocyanate prepolymer obtained by reacting an aromatic or aliphatic polyisocyanate compound having an average molecular weight of 158 to 1,500 and containing 2 or more isocyanate groups in its molecule with a liquid polydiene compound having an average molecular weight of 1,000 to 5,000 and containing in its molecule 2 or more reactive functional groups selected by hydroxyl, amino, carboxyl and epoxy groups, in relative amounts such that the isocyanate groups are in excess of the reactive functional groups; the ratio of the average amino equivalent of polyamine components (1) to (4) to the average isocyanate equivalent of polyisocyanate components (5) to (7) being from 1:0.7 to 1:1.5; and the aliphatic polyisocyanate compound (6) forming at most 20% by weight of the total polyisocyanate component. A composition according to claim 1 wherein the polyoxyalkylene polyamine in the polyoxyalkylene polyamine (B) forms 3.0 - 10.0 weight % of the total weight of the composition. A composition according to claim 1 or claim 2 wherein the polydiene chain in the liquid polyisocyanate prepolymer (7) forms at least 6.5% by weight of the total weight of the composition and the total weight of aromatic ring contained in the structures of (1) to (7) is at most 40% by weight of the total weight of the composition. A composition according to any one of the preceding claims wherein the polyoxyalkylene polyamine (1) forms at most 30% by weight of the total polyamine components (1) to (4).

Inventors: ISHIBASHI HIDEO, IZUMO TAKAHARU, YAMAMOTO SATOSHI, ISHIBASHI, HIDEO, IZUMO, TAKAHARU, YAMAMOTO, SATOSHI
Applicants: NIPPON PAINT CO LTD, NIPPON PAINT CO., LTD.
Application year: 1990
Main classification: C08G18
IPC codes: C08G18, B29C45