Hydrolysis stabilizer for ester group-containing resin and process for hydrolysis stabilization of ester group-containing resin using said hydrolysis stabilizer

Abstract: A hydrolysis stabilizer for an ester group-containing resin, which comprises as a main component a carbodiimide having at least two carbodiimide groups in the molecule and resulting from 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate or a mixture of 4,4'-dicyclohexylmethane diisocyanate and isophorone diisocyanate, or from a mixture of tetramethylxylylene diisocyanate with 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate or a mixture of 4,4'-dicyclohexylmethane diisocyanate and isophorone diisocyanate; and a process for the hydrolysis stabilization of an ester group-containing resin, which comprises mixing a polyester type resin with the above hydrolysis stabilizer.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a hydrolysis stabilizer for an ester group-containing resin and a process for the hydrolysis stabilization of an ester group-containing resin using said hydrolysis stabilizer. More particularly, it relates to a hydrolysis stabilizer for an ester group-containing resin which stabilizer does not generate a bad odor when kneaded with the resin at a high temperature, has an excellent compatibility and reactivity with a resin to which the stabilizer is added, even at a low temperature and exhibits thereby an excellent hydrolysis stabilizing effect and comprises a carbodiimide as a main component, and to a process for the hydrolysis stabilization of an ester group-containing resin using the above hydrolysis stabilizer. Description of Related Art Ester group-containing resins (referred to hereinafter as ester type resins in some cases), for example, polyester polyurethane (PU), polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and the like have excellent elasticity and moldability, and hence, have been employed in various uses. However, for example, the above-mentioned polyester polyurethane resin is usually obtained by urethanizing a diisocyanate such as 4,4'-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI) with a difunctional polyester polyol, so that it has many ester groups in the molecule. Accordingly, it is known that there are such problems that not only is this ester group easily hydrolyzed with moisture to cause reduction of molecular weight, but also the acidic carboxyl group formed by this hydrolysis accelerates the hydrolysis of the ester linkage, so that the strength is reduced and the reduction of strength makes it impossible for the resin per se to resist the strain caused during the curing of the resin, whereby cracking and further reduction of strength are caused. In order to prevent such deterioration of physical properties, it has been tried to add various additives during the molding of a polyester polyurethane resin to trap the carbozyl groups and alcohol groups formed by the hydrolysis, thereby preventing hydrolysis from further proceeding. The above additives include, for example, oxazolines, epoxy compounds, aromatic polycarbodiimides, aliphatic monocarbodiimides. These additives are usually in the form of powder and used in such a manner that they are dry blended with resin pellets or mixed in a given amount with the resin by use of a measuring hopper during molding or spinning, and then, the resulting mixture is melt-kneaded at a given temperature (250-300°C in the case of polyethylene terephthalate). However, the above-mentioned epoxy compounds and oxazolines have no sufficient effect of improving the hydrolysis resistance, increase the melt viscosity of the resin and deteriorate the moldability, so that they have no practical usability. Moreover, the above aromatic carbodiimides are usually thermosetting, and hence, their carbodiimide groups cross-link upon heating and when they are kneaded with the resin, the viscosity of the resulting mixture increases or they become lump-like and are ununiformly dispersed in the resin, and hence, in some cases, no desirable effect of hydrolysis stabilization can be obtained. For the purpose of preventing the above-mentioned problems of aromatic carbodiimides when heated, there have been developed various aromatic carbodiimides having a group of high steric hindrance in the ortho-position to the carbodiimide group. However, these aromatic carbodiimides are pyrolyzed by a heat applied when they are melt-kneaded with a polyester polyurethane resin, and in addition, generate remarkably unpleasant odor due to the vaporization of impurities or starting materials, resulting in a deterioration of working atmosphere. Furthermore, the gas generated contains aromatic amines and hence is very dangerous in view of not only bad odor but also toxicity, and hence, there is such a problem that a large scale deodorizing or ventilating apparatus becomes necessary. Moreover, as aliphatic carbodiimides, the use of dicyclohexylcarbodiimide is well known; however, this dicyclohexylcarbodiimide reacts easily with water to be converted to dicyclohexylurea, and hence, has a problem in that close attention must be paid for preventing moisture in the storage of dicylohexylcarbodiimide. Therefore, it is inadequate to use in industry. Furthermore, a monocarbodiimide is a low molecular weight compound and when added to a polyester polyurethane resin, it bleeds out of the resin, so that it has such a problem that the hydrolysis resistance is not sufficient. SUMMARY OF THE INVENTION It is an object of the present invention to overcome the above disadvantages of the prior art and provide a hydrolysis stabilizer for an ester group-containing resin such as polyester polyurethane resin which stabilizer has an excellent compatibility with said resin, can be easily added without any trouble to said resin during the synthesis and melt-kneading of said resin, has a high molecular weight and, therefore, can sufficiently exhibit the effect of hydrolysis stabilization of the said resin. It is another object of the present invention to provide a process for the hydrolysis stabilizer of an ester group-containing resin using the above hydrolysis stabilizer. According to the present invention, there is provided a hydrolysis stabilizer for an ester group-containing resin, which comprises as a main component a carbodiimide having at least two carbodiimide groups in the molecule and resulting from 4,4'-dicyclohezylmethane diisocyanate represented by the formula (I): or isophorone diisocyanate represented by the formula (II): or a mixture of 4,4'-dicyclohexylmethane diisocyanate of the formula (I) with isophorone diisocyanate of the formula (II) wherein the carbodiimide is end-blocked with a carboxylic acid, an acid anhydride or a monoisocyanate, or, a carbodiimide having at least two carbodiimide groups in the molecule and resulting from a mixture of tetramethylxylylene diisocyanate represented by the formula (III): with 4,4'-dicyclohexylmethane diisocyanate represented by the formula (I), isophorone diisocyanate represented by the formula (II) or a mixture of 4,4'-dicyclohexylmethane diisocyanate of the formula (I) and isophorone diisocyanate of the formula (II) wherein the carbodiimide is end-blocked with a carboxylic acid, an acid anhydride or a monoisocyanate. According to the present invention, there is further provided a process for the hydrolysis stabilization of an ester group-containing resin which comprises mixing a polyester resin with a carbodiimide having at least two carbodiimide groups in the molecule and resulting from 4,4'-dicyclohexylmethane diisocyanate represented by the formula (I): or isophorone diisocyanate represented by the formula (II): or a mixture of 4,4'-dicyclohexylmethane diisocyanate of the formula (I) with isophorone diisocyanate of the formula (II) wherein the carbodiimide is end-blocked with a carboxylic acid, an acid anhydride or a monoisocyanate, or, a carbodiimide having at least two carbodiimide groups in the molecule and resulting from a mixture of tetramethylxylylene diisocyanate represented by the formula (III): with 4,4'-dicyclohexylmethane diisocyanate represented by the formula (I), isophorone diisocyanate represented by the formula (II) or a mixture of 4,4'-dicyclohexylmethane diisocyanate of the formula (I) and isophorone diisocyanate of the formula (II) wherein the carbodiimide is end-blocked with a carboxylic acid, an acid anhydride or a monoisocyanate. DETAILED DESCRIPTION OF THE INVENTION The present hydrolysis stabilizer for an ester group-containing resin comprises as a main component: (1) a carbodiimide having at least two carbodiimide groups in the molecule and resulting from 4,4'-dicyclohexylmethane diisocyanate represented by the above formula (I) (referred to hereinafter as HMDI in some cases), or, isophorone diisocyanate represented by the above formula (II) (referred to hereinafter as IPDI in some cases), or, a mixture of HMDI and IPDI, wherein the carbodiimide is end-blocked with a carboxylic acid, an acid anhydride or a monoisocyanate, or (2) a carbodiimide having at least two carbodiimide groups in the molecule and resulting from a mixture of tetramethylxylylene diisocyanate represented by the above formula (III) (referred to hereinafter as TMXDI in some cases) with HMDI, IPDI or a mixture of HMDI and IPDI, wherein the carbodiimide is end-blocked with a carboxylic acid, an acid anhydride or a monoisocyanate. Said carbodiimide can be produced by subjecting (1) HMDI, IPDI or a mixture of HMDI and IPDI, or (2) a mixture of TMXDI with HMDI, IPDI or a mixture of HMDI and IPDI, as the starting materials to carbodiimidization reaction accompanied by decarboxylation reaction. The above carbodiimidization reaction is effected in the presence of a suitable carbodiimidization catalyst, and as the carbodiimidization catalyst which can be used, organic phosphorus compounds are preferable, and phosphorene oxides are particularly preferable in view of activity. Specifically, there are mentioned 3-methyl-1-phenyl-2-phosphorene-1-oxide, 3-methyl-1-ethyl-2-phosphorene-1-oxide, 1,3-dimethyl-2-phosphorene -1-oxide, 1-phenyl-2-phosphorene-1-oxide, 1-ethyl-2-phosphorene-1-oxide, 1-methyl-2-phosphorene-1-oxide and double bond isomers thereof. Among them, 3-methyl-1-phenyl-2-phosphorene-1-oxide, which is easily commercially available, is particularly preferable. The above carbodiimidization reaction can be carried out by a known method, for example, by adding the above-mentioned catalyst to (1) HMDI, IPDI or a mixture of HMDI and IPDI, or (2) a mixture of TMXDI with HMDI, IPDI or a mixture of HMDI and IPDI in the absence of a solvent or to a solution of (1) or (2) in a solvent inert thereto, in a proportion of 0.1 to 10% by weight (a larger amount is possible when the economy is neglected), preferably 0.5 to 5% by weight, based on the total weight of the isocyanates in the atmosphere of an inert gas such as nitrogen or with bubbling of the inert gas, and then heating the resulting mixture with stirring at a reaction temperature within the range of from 150°C to 200°C, thereby allowing a carbodiimidization reaction accompanied by decarboxylation reaction to proceed. The reaction time for the above reaction is varied depending upon the reaction temperature, the kind and amount of the catalyst, and when, for example, HMDI is used as the starting material and 3-methyl-1-phenyl-2-phosphorene-1-oxide is added in a proportion of 1% by weight based on the total weight of the isocyanates and the reaction is effected at a reaction temperature of 180°C, it is possible to obtain in about 20 hours a carbodiimide compound resulting from HMDI, and even when IPDI is used as the starting material the same applies. When, for example, a mixture of TMXDI and HMDI is used as the starting material, it is possible to obtain a carbodiimide compound resulting from the mixture of TMXDI and HMDI similarly to the above. Incidentally, the proceeding of the reaction may be confirmed by observing the absorption of isocyanate group at 2258 cm -1 in an infrared absorption spectrum or confirmed by a titration method. In the above reaction, when (1) HMDI, IPDI or a mixture of HMDI and IPDI, or (2) a mixture of TMXDI with HMDI, IPDI or a mixture of HMDI and IPDI is used, a carbodiimide represented by the following formula (IV) can be obtained: OCN-(R 1 -NCN) n -R 2 -NCO wherein R 1 and R 2 may be the same as or different from each other and each represents the residue of TMXDI, HMDI or IPDI freed from NCO group; and the polymerization style of the above isocyanates may be a random polymerization or a block polymerization; and n is an integer of 2 or more. The carbodiimide which is the main component of the present hydrolysis stabilizer for an ester group-containing resin, is a product obtained by end-blocking a carbodiimide having terminal isocyanate groups obtained by the above-mentioned method, with a carboxylic acid, an acid anhydride or a monoisocyanate. When the terminal isocyanate of the carbodiimide is blocked with a monoisocyanate, a carbodiimide represented by the following formula (V) can be obtained: R 3 -NCN-(R 5 -NCN) m -R 4 wherein R 3 and R 4 may be the same as or different from each other and each represents the residue of the monoisocyanate freed from NCO group; m is an integer of 1 or more; and R 5 represents the residue of the diisocyanate used in the reaction similarly to R 1 and R 2 . Incidentally, the proportion (mole ratio) of the diisocyanate [(1) HMDI, IPDI or a mixture of HMDI and IPDI or (2) a mixture of TMXDI with HMDI, IPDI or a mixture of HMDI and IPDI] to the monoisocyanate is 1 2 - 30 : 2 , preferably 4 : 2 - 19 : 2, and when the diisocyanate and the monoisocyanate are used in a proportion of 3 : 2, the number of carbodiimide units in one molecule, namely n, becomes 4 and when the proportion is 19 2, n becomes 20. When the terminals of the carbodiimide are blocked with the monoisocyanate, it is favorable, for obtaining a carbodiimide having the desired molecular weight, that the diisocyanate and the monoisocyanate are previously mixed to effect carbodiimidization, because it is possible to control the amount of the monocarbodiimide produced by condensation of the monoisocyanate molecules with each other. The monoisocyanate used for blocking the terminals of the carbodiimide includes n-butyl isocyanate, tert-butyl isocyanate, isobutyl isocyanate, ethyl isocyanate, n-propyl isocyanate, cyclohexyl isocyanate, n-octyl isocyanate , and these may be used alone or in admixture of two or more. Moreover, when the terminals of a carbodiimide are blocked with a monofunctional compound having a group capable of reacting with the isocyanate group, for example, a carboxylic acid or an acid anhydride, a carbodiimide represented by the formula (VI) can be obtained: R 6 -X-(R 1 -NCN) p -R 2 -X-R 7 wherein R 6 and R 7 may be the same as or different from each other and each represents the residue of the monofunctional compound having a group capable of reacting with an isocyanate group, for example, a carboxylic acid or an acid anhydride, formed by reaction with the isocyanate; X represents a bond formed by the reaction of the monofunctional compound having a group capable of reacting with the isocyanate group with the isocyanate; and p is an integer of 2 or more. When the terminals of a carbodiimide are blocked with a monofunctional compound having a group capable of reacting with an isocyanate group, for example, a carboxylic acid or an acid anhydride, the reaction between the isocyanate and the end-blocking agent may be effected before the carbodiimidization or may be effected after the carbodiimidization to a suitable degree of polymerization by adding the end-blocking agent in an amount equivalent to the residual isocyanate. The present hydrolysis stabilizer for an ester group-containing resin comprises the above-mentioned carbodiimide as a main component, and in the actual use, the above carbodiimide may be used as a single component or may be used in combination with an appropriate adjuvant. The present process for the hydrolysis stabilization of an ester group-containing resin comprises mixing the above-mentioned carbodiimide with the ester type resin. The mixing method is not critical and any appropriate mixing method can be adopted. The proportion of the above carbodiimide to the ester group-containing resin is 0.01 to 5% by weight, preferably 0.3 to 1% by weight, and when the proportion is less than 0.01% by weight, the amount of the carbodiimide bond for the ester group becomes small, the hydrolysis stabilization effect cannot be said to be sufficient. When the proportion exceeds 5% by weight, the carbodiimide exhibits its plasticizing effect on the ester group-containing resin and adversely affects the physical properties of the resin. Incidentally, as carbodiimides having particularly preferable hydrolysis resistance, there can be mentioned carbodiimides having a degree of polymerization of 5 to 30 obtained. from HMDI and a monoisocyanate, for example, cyclohexyl isocyanate; carbodiimides having a degree of polymerization of 5 to 30 derived from a mixture of HMDI : TMXDI = 10 : 1 - 1 : 10 and end-blocked with a monoisocyanate such as cyclohexyl isocyanate etc. Document DE-OS 195 25 235 A1 discloses a urea-modified carbodiimide as well as a process for the production thereof. The carbodiimide is used as a hydrolysis stabiliser. The carbodiimide is end-blocked by primary or secondary organic aliphatic amines in order to introduce urea-bonds into the carbodiimide. JP-A-07-017939 discloses isocyanate-terminated carbodiimides having a degree of polymerization (n) of 0 to 10 and an improved compatibility. However, this isocyanate is low in reactivity owing to steric hindrance and when the carbodiimide is mixed with the ester group-containing resin, the reaction of the isocyanate with the carboxyl or hydroxyl group present at the ends of the ester group-containing resin is slow and the isocyanate remains as such in the ester group-containing resin even after the melt-kneading. Therefore, there is such a problem that this isocyanate reacts with moisture to generate carbon dioxide, whereby voids and the like are formed in the ester group-containing resin. On the other hand, in the case of the present hydrolysis stabilizer for an ester group-containing resin, the reactivity of the terminal isocyanate group of the carbodiimide resulting from HMDI, IPDI or a mixture of HMDI and IPDI which is the main component of the hydrolysis stabilizer, is sufficiently high even when the carbodiimide results from a mixture of TMXDI with HMDI, IPDI or a mixture of HMDI and IPDI. When the carbodiimide is melt-kneaded with the ester group-containing resin, the terminal isocyanate groups are consumed by the reaction with the carboxyl or hydroxyl group present at the ends of the ester group-containing resin, and there is substantially no case where the isocyanate remains as such in the ester group-containing resin after the melt-kneading. Therefore, there is no problem of voids due to carbon dioxide. Furthermore, JP-A-07-017939 discloses carbodiimides in which the terminal isocyanates are blocked with an alcohol or an amine. However, as described above, this carbodiimide is low in reactivity because of steric hindrance, and in order to obtain the desired hydrolysis stabilizing effect, it is necessary that the carbodiimide be added in an amount as large as possible within the limited addition amount range (when the amount of the carbodiimide added is too large, there appears a plasticizing effect on the ester group-containing resin). Accordingly, the blocking of the terminal isocyanate group with an alcohol or an amine results in an increase of molecular weight and also a decrease of the above-mentioned addition amount, and hence, is not desirable in view of the hydrolysis stabilizing effect. On the other hand, in the case of the present hydrolysis stabilizer for an ester group-containing resin, the reactivity of the terminal isocyanate group of the carbodiimide which is the main component of the stabilizer, is sufficiently high as described above, and hence, even when the terminal isocyanate group is blocked with an alcohol or an amine to increase the molecular weight, a sufficient hydrolysis stabilizing effect is exhibited without increasing the addition amount so much. DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples are shown below to explain the present invention in more detail. Examples marked with an asterisk are not falling within the scope of the invention. Synthesis of carbodiimides Synthesis Example 1 (*) To 300 g of HMDI was added, as a carbodiimidization catalyst, 1.5 g of 3-methyl-1-phenyl-2-phosphorene-1-oxide (referred to hereinafter as carbodiimidization catalyst), and they were subjected to a condensation reaction at 180°C for 10 hours in a nitrogen atmosphere to obtain a carbodiimide resulting from HMDI (degree of polymerization = 3). Synthesis Examples 2 to 4 (*) The same procedure as in Synthesis Example 1 was repeated, except that the reaction time was changed as shown in Table 1 to obtain carbodiimides as shown in Table 1. Synthesis Example Reaction time (hr) Polymerization degree 2 (*) 15 10 3 (*) 27 20 4 (*) 35 30 Synthesis Example 5 (*) To 300 g of HMDI was added 1.5 g of the carbodiimidization catalyst and they were subjected to a reaction at 185°C for 5 hours while nitrogen was bubbled thereinto, to obtain a carbodiimide resulting from HMDI (degree of polymerization = 10). Synthesis Examples 6 to 8 (*) The same procedure as in Synthesis Example 1 was repeated, except that the reaction time was changed as shown in Table 2 to obtain carbodiimides shown in Table 2. Synthesis Example Reaction time (hr) Polymerization degree 6 16 10 7 28 20 8 38 30 Synthesis Example 9 To a mixture of 236 g of HMDI with 25.0 g of cyclohexyl isocyanate (referred to hereinafter as CHI) was added 2.60 g of the carbodiimidization catalyst, and they were subjected to a reaction at 185°C for 19 hours while nitrogen was bubbled thereinto, to obtain a carbodiimide resulting from HMDI and CHI (degree of polymerization = 10). Synthesis Examples 10 to 14 The starting materials and the reaction conditions were changed as shown in Table 3 to obtain carbodiimides shown in Table 3 in which CHI means a cyclohexyl isocyanate. Synthesis Example 10 11 12 13 14 Diisocyanate Amount (g) HMDI 498 HMDI 760 IPDI 200 IPDI 400 IPDI 622 Monoisocyanate Amount (g) CHI 25 CHI 25 CHI 25 CHI 25 CHI 25 Catalyst amount (g) 5.2 7.8 2.3 4.3 6.2 Reaction time (hr) 20 48 21 27 52 Polymerization degree 20 30 10 20 30 Synthesis Example 15 (*) To 288 g of HMDI was added 20 g of cyclohexylamine and they were stirred at 100°C for one hour while nitrogen was bubbled thereinto and subsequently 2.9 g of the carbodiimidization catalyst was added thereto, after which the resulting mixture was subjected to a reaction at 185°C for 30 hours, to obtain a carbodiimide resulting from HMDI and having terminal urea bonds (degree of polymerization = 10). Synthesis Examples 16 to 30 The end-blocking agent was changed to an alcohol, an amine, a carboxylic acid or an acid anhydride as shown in Tables 4, 5 and 6, and in the same manner as in Synthesis Example 15, there were obtained carbodiimides having a urea bond, a urethane bond, an imido bond or an amido bond in the molecular chain as shown in Tables 4, 5 and 6. Synthesis Example 16 (*) 17 (*) 18 (*) 19 20 Diisocyanate Amount (g) HMDI 498 IPDI 245 IPDI 467 HMDI 288 HMDI 498 Blocking agent Cyclohexylamine Do. Do. Cyclohexylcarboxylic acid Do. Amount (g) 20 20 20 26 26 Catalyst amount (g) 5.5 2.5 4.7 2.9 5.5 Reaction time (hr) 52 30 50 32 48 Polymerization degree 20 10 20 10 20 Synthesis Example 21 22 23 24 25 (*) Diisocyanate Amount (g) HMDI 288 HMDI 498 HMDI 288 HMDI 498 HMDI 288 Blocking agent Phthalic anhydride Do. Benzoic acid Do. Dibutylamine Amount (g) 30 30 24 24 26 Catalyst amount (g) 2.9 5.5 2.9 5.5 2.9 Reaction time (hr) 35 52 31 50 32 Polymerization degree 10 20 10 20 10 Synthesis Example 26 (*) 27 28 29 30 Diisocyanate HMDI IPDI IPDI IPDI IPDI Amount (g) 498 245 467 245 467 Blocking agent Dibutyl-amine Cyclohexyl-carboxylic acid Do. Phthalic anhydride Do. Amount (g) 26 26 26 30 30 Catalyst amount (g) 5.5 2.5 4.7 2.5 4.7 Reaction time (hr) 48 30 50 30 50 Polymerization degree 20 10 20 10 20 Example 1 A polybutylene terephthalate [PBT] manufactured by DAINIPPON INK & CHEMICALS INC. (Product No. BT-1000) was melt-kneaded with 1% by weight of the present hydrolysis stabilizer for an ester group-containing resin which comprised as the main component one of the carbodiimides obtained in Synthesis Examples 1 to 30, by means of a twin screw extruder and injection molded into JIS-K6301 Dumbbell No. 4. The sample thus obtained was immersed in hot water at 95°C and the tensile strength of the sample was measured by a tensile tester every time shown in Table 7. The results are shown in Tables 7 to 9 [incidentally, in Tables 7 to 9, the numerals in the uppermost section refer to Synthesis Example Nos. in which the carbodiimide was synthesized, and the term "blank" means a sample in which no present hydrolysis stabilizer for an ester group-containing resin was used (the same applies hereinafter)]. t/day blank 1(*) 2(*) 3(*) 4(*) 5(*) 6(*) 7(*) 8(*) 9 0 610 610 610 610 620 610 610 610 610 610 10 410 520 540 540 540 520 530 530 540 570 15 250 400 420 430 430 400 420 420 420 460 20 150 200 230 230 230 190 220 230 230 260 30 100 150 170 170 170 140 170 170 170 190 (Kg/cm 2 ) t/day 10 11 12 13 14 15(*) 16(*) 17(*) 18(*) 19 0 610 620 610 610 610 610 610 610 610 610 10 580 590 560 570 570 580 580 560 560 560 15 470 480 450 460 460 470 470 450 450 450 20 260 270 250 260 260 260 270 250 250 240 30 200 200 190 190 200 200 200 180 190 170 (Kg/cm 2 ) t/day 20 21 22 23 24 25(*) 26(*) 27 28 29 30 0 610 610 610 610 610 600 600 610 600 610 610 10 560 560 570 560 560 570 570 550 560 560 560 15 450 450 450 450 450 460 460 440 450 440 450 20 250 250 250 240 250 260 270 240 240 240 250 30 180 180 180 170 180 190 200 170 170 170 170 (Kg/cm 2 ) Example 2 To a urethane elastomer manufactured by Nisshinbo Industries, Inc. (Reference No. F-30) was added 1% by weight of the present hydrolysis stabilizer for an ester group-containing resin comprising as the main component one of the carbodiimides obtained in Synthesis Examples 1 to 30, and the resulting mixture was molded into a film by a cast method, after which the film was punched to JIS-K6301 Dumbbell No. 4. The sample thus obtained was immersed in hot water at 95°C and the tensile strength of the sample was measured by a tensile tester every time shown in Tables 10 to 12. The results are shown in Tables 10 to 12. t/day blank 1(*) 2(*) 3(*) 4(*) 5(*) 6(*) 7(*) 8(*) 9 0 870 880 880 890 890 870 880 880 880 870 3 520 650 660 660 660 640 650 650 660 710 7 140 570 580 590 590 560 570 570 570 590 10 - 510 520 530 530 500 510 500 510 530 15 - 190 200 200 200 110 110 200 210 210 (Kg/cm 2 ) t/day 10 11 12 13 14 15(*) 16(*) 17(*) 18(*) 19 20 0 880 880 880 880 880 870 870 870 870 870 870 3 710 720 710 710 710 710 710 700 700 710 710 7 600 600 590 590 600 350 350 320 350 580 580 10 530 530 520 540 540 320 340 300 310 500 500 15 240 250 200 190 200 110 130 100 120 190 200 (Kg/cm 2 ) t/day 21 22 23 24 25(*) 26(*) 27 28 29 30 0 870 870 870 870 880 880 870 870 870 870 3 700 710 710 710 710 720 670 670 670 640 7 560 570 570 570 570 580 530 550 540 550 10 500 510 500 510 510 510 470 480 510 510 15 180 190 170 180 170 180 140 170 170 180 (Kg/cm 2 ) -: destructed Example 3 A polybutylene terephthalate [PBT] elastomer manufactured by DAINIPPON INK & CHEMICALS, INC. (Product No. GRILUX [registered trademark] EH-700) and 0.5% by weight of the present hydrolysis stabilizer for an ester group-containing resin comprising as the main component one of the carbodiimides obtained in Synthesis Examples 1 to 30 were melt-mixed and extruded using a twin screw extruder and then formed into a film of about 500 µm using a T-die, after which the film thus obtained was injection molded into JIS-K6301 Dumbbell No. 4. The sample thus obtained was immersed in hot water at 95°C and the tensile strength was measured by a tensile tester every time shown in Tables 13 to 15. The results are shown in Tables 13 to 15. t/day blank 1(*) 2(*) 3(*) 4(*) 5(*) 6(*) 7(*) 8(*) 9 10 0 350 350 350 350 350 350 350 350 350 350 350 10 330 350 350 350 350 340 340 340 350 350 350 15 310 340 350 350 350 330 340 340 340 350 350 20 290 320 330 340 340 320 330 340 340 350 350 30 220 320 330 330 340 310 320 330 330 340 340 (Kg/cm 2 ) t/day 11 12 13 14 15(*) 16(*) 17(*) 18(*) 19 20 21 0 350 350 350 350 350 350 350 350 350 350 350 10 350 350 350 350 350 350 350 350 340 340 340 15 350 350 350 350 350 350 350 340 340 340 340 20 350 340 340 340 350 350 340 340 330 330 320 30 340 330 340 340 340 340 330 330 320 320 310 (Kg/cm 2 ) t/day 22 23 24 25(*) 26(*) 27 28 29 30 0 350 350 350 350 350 350 350 350 350 10 340 340 340 350 350 340 340 340 340 15 340 330 330 340 340 330 330 320 330 20 320 310 320 330 340 320 320 310 310 30 310 300 310 320 320 300 300 300 300 (Kg/cm 2 ) Example 4 A polyethylene terephthalate [PET] resin manufactured by KANEBO LTD. (Product No. EFG-7) and 0.5% by weight of the present hydrolysis stabilizer for an ester group-containing resin comprising as the main component one of the carbodiimides obtained in Synthesis Examples 1 to 30 were melt-mixed and extruded using a twin screw extruder and then formed into a film of about 500 µm using a T-die, after which the film thus obtained was injection molded into JIS-K6301 Dumbbell No. 4. The sample thus obtained was immersed in hot water at 95°C and the tensile strength was measured by a tensile tester every time shown in Tables 16 to 18. The results are shown in Tables 16 to 18. t/day blank 1(*) 2(*) 3(*) 4(*) 5(*) 6(*) 7(*) 8(*) 9 10 0 630 630 630 630 630 630 630 630 630 630 630 10 640 650 650 640 650 650 650 650 650 650 640 30 590 650 650 650 650 650 650 650 650 650 650 60 460 630 640 640 640 620 630 640 640 650 650 (Kg/cm 2 ) t/day 11 12 13 14 15(*) 16(*) 17(*) 18(*) 19 20 21 0 630 630 630 630 630 630 630 630 630 630 630 10 650 640 650 650 650 650 650 650 650 650 650 30 650 650 650 650 650 650 650 650 650 650 650 60 650 620 630 630 640 650 620 620 600 600 600 (Kg/cm 2 ) t/day 22 23 24 25(*) 26(*) 27 28 29 30 0 630 630 630 630 630 630 630 630 630 10 650 650 650 650 650 650 650 650 650 30 650 650 650 650 650 650 650 650 650 60 620 600 600 640 640 600 600 600 600 (Kg/cm 2 ) Synthesis of carbodiimides Synthesis Examples 31 to 39 To one of the diisocyanate mixtures shown in Tables 19 and 20 was added 1.5% by weight, based on the total weight of the isocyanates, of the carbodiimidization catalyst and the resulting mixture was heated at 185°C to be subjected to a reaction until the degree of polymerization (n) became 10. Synthesis Example 31(*) 32(*) 33(*) 34(*) 35(*) 36(*) Diisocyanate Amount (g) HMDI 65.5 HMDI 131.0 HMDI 196.5 IPDI 55.6 IPDI 111.1 IPDI 166.7 TMXDI 183.0 TMXDI 122.0 TMXDI 61.0 TMXDI 183.0 TMXDI 122.0 TMXDI 61.0 Monoisocyanate Not used Not used Not used Not used Not used Not used Catalyst amount (g) 3.7 3.8 3.9 3.6 3.5 3.4 Reaction time (hr) 30 25 20 30 26 20 Polymerization degree 10 10 10 10 10 10 Synthesis Example 37(*) 38(*) 39(*) Diisocyanate Amount (g) HMDI 65.5 HMDI 131.0 HMDI 196.5 IPDI 166.7 IPDI 111.1 IPDI 55.6 Monoisocyanate Not used Not used Not used Catalyst amount (g) 3.5 3.6 3.8 Reaction time (hr) 20 19 19 Polymerization degree 10 10 10 Synthesis Examples 40 to 48 To one of the mixtures shown in Tables 21 and 22 was added cyclohexyl isocyanate so that the degree of polymerization (n) becomes 10 (diisocyanate : monoisocyanate = 9 : 2 by mole), and the carbodiimidization catalyst was added in a proportion of 1.5% by weight based on the total weight of the isocyanates, after which the resulting mixture was heated at 185°C to be subjected to a reaction until the peak of the isocyanate disappeared in the infrared absorption (IR) spectrum. Synthesis Example 40 41 42 Diisocyanate HMDI 65.5 HMDI 131.0 HMDI 196.5 Amount (g) TMXDI TMXDI TMXDI 183.0 122.0 61.0 Monoisocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Amount (g) 27.8 27.8 27.8 Catalyst amount (g) 4.1 4.2 4.3 Reaction time (hr) 28 24 19 Polymerization degree 10 10 10 Synthesis Example 43 44 45 46 47 48 IPDI IPDI IPDI HMDI HMDI HMDI Diisocyanate 55.6 111.1 166.7 65.5 131.0 196.5 Amount (g) TMXDI TMXDI TMXDI IPDI IPDI IPDI 183.0 122.0 61.0 166.7 111.1 55.6 Monoisocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Amount (g) 27.8 27.8 27.8 27.8 27.8 27.8 Catalyst amount (g) 4.0 3.9 3.8 3.5 3.6 3.8 Reaction time (hr) 30 25 20 21 20 20 Polymerization degree 10 10 10 10 10 10 Synthesis Examples 49 to 57 To one of the mixtures shown in Tables 23 and 24 was added cyclohexylamine so that the degree of polymerization (n) became 10 (diisocyanate : amine = 11 : 2 by mole), and the carbodiimidization catalyst was added in a proportion of 1.5% by weight based on the total weight of the isocyanates, after which the resulting mixture was heated at 185°C to be subjected to a reaction until the peak of the isocyanate disappeared in IR. Synthesis Example 49(*) 50(*) 51(*) 52(*) 53(*) 54(*) Diisocyanate Amount (g) HMDI 65.5 HMDI 131.0 HMDI 196.5 IPDI 55.6 IPDI 111.1 IPDI 166.7 TMXDI 183.0 TMXDI 122.0 TMXDI 61.0 TMXDI 183.0 TMXDI 122.0 TMXDI 61.0 Amine Cyclohexyl amine Cyclohexyl amine Cyclohexyl amine Cyclohexyl amine Cyclohexyl amine Cyclohexyl amine Amount (g) 22.0 22.0 22.0 22.0 22.0 22.0 Catalyst amount (g) 3.7 3.8 3.9 3.6 3.5 3.4 Reaction time (hr) 29 25 19 30 25 20 Polymerization degree 9 9 9 9 9 9 Synthesis Example 55(*) 56(*) 57(*) Diisocyanate Amount (g) HMDI 65.5 HMDI 131.3 HMDI 196.5 IPDI 166.7 IPDI 111.1 IPDI 55.6 Amine Cyclohexyl amine Cyclohexyl amine Cyclohexyl amine Amount (g) 22.0 22.0 22.0 Catalyst amount (g) 3.5 3.6 3.8 Reaction time (hr) 19 22 20 Polymerization degree 9 9 9 Synthesis Examples 58 to 66 To one of the mixtures shown in Tables 25 and 26 was added cyclohexyl isocyanate so that the degree of polymerization (n) became 20 (diisocyanate : monoisocyanate = 19 : 2 by mole) and the carbodiimidization catalyst was added in a proportion of 1.5% by weight based on the total weight of the isocyanates, after which the resulting mixture was heated at 185°C to be subjected to a reaction until the peak of the isocyanate disappeared in IR. Synthesis Example 58 59 60 HMDI HMDI HMDI Diisocyanate 65.5 131.0 196.5 Amount (g) TMXDI TMXDI TMXDI 183.0 122.0 61.0 Monoisocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Amount (g) 13.2 13.2 13.2 Catalyst amount (g) 3.9 4.0 4.1 Reaction time (hr) 30 24 21 Polymerization degree 20 20 20 Synthesis Example 61 62 63 64 65 66 Diisocyanate Amount (g) IPDI 55.6 IPDI 111.1 IPDI 166.7 HMDI 65.5 HMDI 131.0 HMDI 196.5 TMXDI 183.0 TMXDI 122.0 TMXDI 61.0 IPDI 166.7 IPDI 111.1 IPDI 55.6 Monoisocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Cyclohexyl isocyanate Amount (g) 13.2 13.2 13.2 13.2 13.2 13.2 Catalyst amount (g) 3.8 3.7 3.6 3.7 3.8 4.0 Reaction time (hr) 29 24 20 23 19 20 Polymerization degree 20 20 20 20 20 20 Synthesis Examples 67 to 75 To one of the mixtures shown in Tables 27 and 28 was added cyclohexylamine so that the degree of polymerization (n) became 20 (diisocyanate : amine = 21 : 2 by mole), and the carbodiimidization catalyst was added in a proportion of 1.5% by weight based on the total weight of the isocyanates, after which the resulting mixture was heated at 185°C to be subjected to a reaction until the peak of the isocyanate disappeared in IR. Synthesis Example 67(*) 68(*) 69(*) 70(*) 71(*) 72(*) Diisocyanate Amount (g) HMDI 65.5 HMDI 131.0 HMDI 196.5 IPDI 55.6 IPDI 111.1 IPDI 166.7 TMXDI 183.0 TMXDI 122.0 TMXDI 61.0 TMXDI 183.0 TMXDI 122.0 TMXDI 61.0 Amine Cyclohexyl amine Cyclohexyl amine Cyclohexyl amine Cyclohexyl amine Cyclohexyl amine Cyclohexyl amine Amount (g) 10.4 10.4 10.4 10.4 10.4 10.4 Catalyst amount (g) 3.7 3.8 3.9 3.6 3.5 3.4 Reaction time (hr) 52 50 48 51 50 50 Polymerization degree 19 19 19 19 19 19 Synthesis Example 73(*) 74(*) 75(*) Diisocyanate Amount (g) HMDI 65.5 HMDI 131.0 HMDI 196.5 IPDI 166.7 IPDI 111.1 IPDI 55.6 Amine Cyclohexyl amine Cyclohexyl amine Cyclohexyl amine Amount (g) 10.4 10.4 10.4 Catalyst amount (g) 3.5 3.6 3.8 Reaction time (hr) 47 48 48 Polymerization degree 19 19 19 synthesis Examples 76 to 84 To one of the mixtures shown in Tables 29 and 30 was added cyclohexylcarboxylic acid so that the degree of polymerization (n) became 9 (diisocyanate : cyclohexylcarboxylic acid = 10 : 2 by mole), and the carbodiimidization catalyst was added in a proportion of 1.5% by weight based on the total weight of the isocyanates, after which the resulting mixture was heated at 185°C to be subjected to a reaction until the peak of the isocyanate disappeared in IR. Synthesis Example 76 77 78 HMDI HMDI HMDI Diisocyanate 65.5 131.0 196.5 Amount (g) TMXDI TMXDI TMXDI 183.0 122.0 61.0 Carboxylic acid Cyclohexyl carboxylic acid Cyclohexyl carboxylic acid Cyclohexyl carboxylic acid Amount (g) 28.5 28.5 28.5 Catalyst amount (g) 3.7 3.8 3.9 Reaction time (hr) 30 25 20 Polymerization degree 9 9 9 Synthesis Example 79 80 81 82 83 84 IPDI IPDI IPDI HMDI HMDI HMDI Diisocyanate 55.6 111.1 166.7 65.5 131.0 196.5 Amount (g) TMXDI TMXDI TMXDI IPDI IPDI IPDI 183.0 122.0 61.0 166.7 111.1 55.6 Carboxylic acid Cyclohexyl carboxylic acid Cyclohexyl carboxylic acid Cyclohexyl carboxylic acid Cyclohexyl carboxylic acid Cyclohexyl carboxylic acid Cyclohexyl carboxylic acid Amount (g) 28.5 28.5 28.5 28.5 28.5 28.5 Catalyst amount (g) 3.6 3.5 3.4 3.5 3.6 3.8 Reaction time (hr) 30 26 20 20 19 19 Polymerization degree 9 9 9 9 9 9 Synthesis Examples 85 to 92 To one of the mixtures shown in Tables 31 and 32 was added phthalic anhydride so that the degree of polymerization (n) became 9 (diisocyanate : phthalic anhydride = 10 : 2 by mole), and the carbodiimidization catalyst was added in a proportion of 1.5% by weight based on the total weight of the isocyanates, after which the resulting mixture was heated at 185 °C to be subjected to a reaction until the peak of the isocyanate disappeared in IR. Synthesis Example 85 86 87 88 89 90 Diisocyanate Amount (g) HMDI 65.5 HMDI 131.0 HMDI 196.5 IPDI 55.6 IPDI 111.1 IPDI 166.7 TMXDI 183.0 TMXDI 122.0 TMXDI 61.0 TMXDI 183.0 TMXDI 122.0 TMXDI 61.0 Acid anhydride Phthalic anhydride Phthalic anhydride Phthalic anhydride Phthalic anhydride Phthalic anhydride Phthalic anhydride Amount (g) 32.9 32.9 32.9 32.9 32.9 32.9 Catalyst amount (g) 3.7 3.8 3.9 3.6 3.5 3.4 Reaction time (hr) 28 24 19 30 25 20 Polymerization degree 9 9 9 9 9 9 Synthesis Example 90 91 92 Diisocyanate Amount (g) HMDI 65.5 HMDI 131.0 HMDI 196.5 IPDI 166.7 IPDI 111.1 IPDI 55.6 Acid anhydride Phthalic anhydride Phthalic anhydride Phthalic anhydride Amount (g) 32.9 32.9 32.9 Catalyst amount (g) 3.5 3.6 3.8 Reaction time (hr) 21 20 20 Polymerization degree 9 9 9 Example 5 A polybutylene terephthalate [PBT] manufactured by DAINIPPON INK & CHEMICALS, INC. (Product No. BT-1000) and 1% by weight of the present hydrolysis stabilizer for an ester group-containing resin comprising as the main component one of the carbodiimides obtained in Synthesis Examples 31 to 92 were melt-kneaded using a twin screw extruder and then injection molded into JIS-K6301 Dumbbell No. 4. The sample thus obtained was immersed in hot water at 95°C and the tensile strength was measured by a tensile tester every time shown in Tables 33 to 38. The results are shown in Tables 33 to 38. t/day 31(*) 32(*) 33(*) 34(*) 35(*) 36(*) 37(*) 38(*) 39(*) 40 41 0 610 620 620 610 620 620 620 620 620 620 620 10 540 550 540 540 530 530 540 530 520 570 580 15 410 420 420 420 430 420 430 420 430 450 460 20 230 240 230 250 240 240 230 230 240 250 260 30 180 170 180 170 170 180 180 180 170 180 190 (Kg/cm 2 ) t/day 42 43 44 45 46 47 48 49(*) 50(*) 51(*) 52(*) 0 610 610 610 610 620 610 620 610 610 620 610 10 580 590 570 580 570 590 590 530 560 540 540 15 470 470 480 470 460 470 480 430 440 420 420 20 270 270 460 270 250 270 280 240 250 250 240 30 190 180 190 200 190 180 180 170 180 180 170 (Kg/cm 2 ) t/day 53(*) 54(*) 55(*) 56(*) 57(*) 58 59 60 61 62 63 0 610 620 610 620 610 610 610 610 620 610 610 10 560 540 530 540 560 560 570 580 570 590 590 15 440 420 450 450 440 470 480 470 460 470 470 20 250 250 240 240 230 270 260 270 250 270 270 30 180 180 180 170 170 180 190 200 190 180 180 (Kg/cm 2 ) t/day 64 65 66 67(*) 68(*) 69(*) 70(*) 71(*) 72(*) 73(*) 74(*) 0 610 610 610 620 610 620 610 610 620 610 620 10 570 680 570 540 530 540 560 590 540 530 540 15 480 470 480 420 450 450 440 470 420 450 450 20 260 260 260 250 240 240 230 270 250 240 240 30 190 180 190 180 180 170 170 180 180 180 170 (Kg/cm 2 ) t/day 75(*) 76 77 78 79 80 81 82 83 84 85 0 610 600 610 610 600 610 600 610 600 610 600 10 570 520 520 530 530 530 520 530 520 520 530 15 470 420 430 430 440 430 430 420 430 430 430 20 250 220 230 210 220 230 230 240 230 230 230 30 180 130 140 130 140 150 150 130 140 140 140 (Kg/cm 2 ) t/day 86 87 88 89 90 91 92 0 610 600 610 610 610 610 610 10 530 530 520 530 530 520 520 15 440 430 430 440 430 430 440 20 220 230 230 220 230 230 240 30 140 150 150 140 150 150 150 (Kg/cm 2 ) Example 6 To a urethane elastomer manufactured by Nisshinbo Industries Inc. (Product No. F-30) was added 1% by weight of the present hydrolysis stabilizer for an ester group-containing resin comprising as the main component one of the carbodiimides obtained in Synthesis Examples 31 to 92 and then the resulting mixture was formed into a film by a cast method, after which the film was punched to obtain JIS-K6301 Dumbbell No. 4. The sample thus obtained was immersed in hot water at 95°C and the tensile strength was measured by a tensile tester every time shown in Tables 39 to 44. The results are shown in Tables 39 to 44. t/day 31(*) 32(*) 33(*) 34(*) 35(*) 36(*) 37(*) 38(*) 39(*) 40 41 0 890 890 880 880 870 880 890 880 890 890 880 3 650 640 650 670 650 640 650 640 650 710 700 7 580 590 590 580 600 590 580 590 580 600 600 10 530 530 540 530 520 520 510 520 520 530 510 15 180 170 160 150 160 170 160 150 140 200 210 (Kg/cm 2 ) t/day 42 43 44 45 46 47 48 49(*) 50(*) 51(*) 52(*) 0 870 870 870 860 870 860 880 870 870 870 880 3 680 690 670 680 690 700 680 650 640 650 650 7 600 590 580 570 580 590 580 600 590 580 590 10 510 510 500 480 500 500 490 520 520 510 540 15 210 190 200 210 200 210 200 160 170 160 160 (Kg/cm 2 ) t/day 53(*) 54(*) 55(*) 56(*) 57(*) 58 59 60 61 62 63 0 870 880 890 880 890 870 870 870 870 860 870 3 640 650 670 650 650 670 680 690 670 680 690 7 590 580 590 600 590 580 600 590 580 570 580 10 520 510 520 520 540 500 510 510 500 480 500 15 170 160 150 160 170 200 210 190 200 210 200 (Kg/cm 2 ) t/day 64 65 66 67(*) 68(*) 69(*) 70(*) 71(*) 72(*) 73(*) 74(*) 0 860 860 890 870 860 890 890 880 890 890 890 3 700 680 650 670 680 650 650 650 670 650 650 7 590 570 590 600 580 590 590 580 590 590 590 10 500 480 540 490 500 540 540 510 520 540 540 15 210 210 170 170 180 170 170 160 150 180 170 (Kg/cm 2 ) t/day 75(*) 76 77 78 79 80 81 82 83 84 85 0 860 860 890 870 860 890 880 890 870 860 890 3 680 680 650 670 680 650 650 650 670 680 650 7 580 570 590 600 580 590 580 590 600 580 590 10 500 480 540 490 500 540 510 540 490 500 540 15 180 210 170 170 180 170 160 170 170 180 170 (Kg/cm 2 ) t/day 86 87 88 89 90 91 92 0 860 890 890 870 860 890 890 3 680 650 650 670 680 650 650 7 570 590 590 600 580 590 590 10 480 540 540 490 500 540 540 15 210 170 170 170 180 170 170 (Kg/cm 2 ) Example 7 To a polybutylene terephthalate [PBT] elastomer manufactured by DAINIPPON INK & CHEMICALS, INC. (Product No. GRILUX [registered trademark] EH-700) was added 0.5% by weight of the present hydrolysis stabilizer for an ester group-containing resin comprising as the main component one of the carbodiimides obtained in Synthesis Examples 31 to 92 and the resulting mixture was melt-mixed and extruded using a twin screw extruder and then formed into a film of about 500 µm using a T-die, after which the film thus obtained was injection molded to obtain JIS-K6301 Dumbbell No. 4. The sample thus obtained was immersed in hot water at 95°C and the tensile strength was measured by a tensile tester every time shown in Tables 45 to 50. The results are shown in Tables 45 to 50. t/day 31(*) 32(*) 33(*) 34(*) 35(*) 36(*) 37(*) 38(*) 39(*) 40 41 0 350 350 350 350 350 350 350 350 350 350 350 5 340 340 350 340 350 340 340 340 340 350 350 10 330 340 340 340 340 330 330 330 330 340 340 20 320 330 320 330 320 320 320 320 320 340 340 30 310 320 310 320 310 310 310 310 310 330 330 (Kg/cm 2 ) t/day 42 43 44 45 46 47 48 49(*) 50(*) 51(*) 52(*) 0 350 350 350 350 350 350 350 350 350 350 350 5 350 340 350 340 340 340 340 350 350 350 350 10 340 330 340 330 340 340 330 340 340 340 340 20 330 320 330 320 330 340 320 330 330 330 330 30 330 310 330 320 320 330 310 320 320 320 320 (Kg/cm 2 ) t/day 53(*) 54(*) 55(*) 56(*) 57(*) 58 59 60 61 62 63 0 350 350 350 350 350 350 350 350 350 350 350 5 340 350 340 350 340 340 340 340 350 350 350 10 330 340 330 340 340 330 330 330 340 340 340 20 320 330 320 330 330 320 330 320 330 330 330 30 310 320 310 320 320 310 310 310 320 320 320 (Kg/cm 2 ) t/day 64 65 66 67(*) 68(*) 69(*) 70(*) 71(*) 72(*) 73(*) 74(*) 0 350 350 350 350 350 350 350 350 350 350 350 5 340 340 340 340 340 340 340 340 340 340 340 10 330 340 340 340 330 330 330 340 340 330 340 20 320 330 340 330 330 320 320 330 330 330 330 30 320 320 330 330 310 310 300 310 320 310 320 (Kg/cm 2 ) t/day 75(*) 76 77 78 79 80 81 82 83 84 85 0 350 350 350 350 350 350 350 350 350 350 350 5 340 340 350 340 340 340 340 350 350 340 340 10 330 330 340 340 330 330 330 340 340 340 330 20 330 320 330 330 320 330 320 330 330 330 320 30 320 310 320 320 310 310 310 320 320 320 310 (Kg/cm 2 ) t/day 86 87 88 89 90 91 92 0 350 350 350 350 350 350 350 5 340 350 340 340 340 340 350 10 330 340 340 330 330 330 340 20 320 330 330 320 330 320 330 30 310 320 320 310 310 310 320 (Kg/cm 2 ) Example 8 A polyethylene terephthalate [PET] resin manufactured by KANEBO LTD. (Product No. EFG-7) and 0.5% by weight of the present hydrolysis stabilizer for an ester group-containing resin comprising as the main component one of the carbodiimides obtained in Synthesis Examples 31 to 92 were melt-mixed and extruded using a twin screw extruder and then formed into a film of about 500 µm using a T-die, after which the film thus obtained was injection molded to obtain JIS-K6301 Dumbbell No. 4. The sample thus obtained was immersed in hot water at 95°C and the tensile strength was measured by a tensile tester every time shown in Tables 51 to 56. The results are shown in Tables 51 to 56. t/day 31(*) 32(*) 33(*) 34(*) 35(*) 36(*) 37(*) 38(*) 39(*) 40 41 0 630 630 630 630 630 630 630 630 630 630 630 10 650 640 650 650 640 650 650 650 640 640 650 30 650 650 640 650 650 650 640 640 640 650 650 60 620 620 640 620 620 630 640 630 630 640 640 (Kg/cm 2 ) t/day 42 43 44 45 46 47 48 49(*) 50(*) 51(*) 52(*) 0 630 630 630 630 630 630 630 630 630 630 630 10 650 650 640 650 650 650 650 650 640 650 650 30 640 650 650 650 640 650 650 650 640 640 650 60 630 630 640 640 630 640 630 640 620 610 610 (Kg/cm 2 ) t/day 53 (*) 54 (*) 55 (*) 56 (*) 57 (*) 58 59 60 61 62 63 0 630 630 630 630 630 630 630 630 630 630 630 10 640 640 650 650 650 650 640 650 650 650 650 30 650 640 650 650 650 640 650 650 650 640 640 60 630 620 620 630 620 610 610 620 610 610 610 (Kg/cm 2 ) t/day 64 65 66 67(*) 68(*) 69(*) 70(*) 71(*) 72(*) 73(*) 74(*) 0 630 630 630 630 630 630 630 630 630 630 630 10 640 640 640 650 650 640 650 650 650 650 650 30 640 650 650 650 650 640 650 650 650 650 650 60 640 630 640 610 610 600 610 610 630 610 620 (Kg/cm 2 ) t/day 75(*) 76 77 78 79 80 81 82 83 84 85 0 630 630 630 630 630 630 630 630 630 630 630 10 650 640 640 650 650 640 650 650 650 640 650 30 640 650 650 650 650 640 650 650 650 640 650 60 610 630 640 610 610 600 610 610 610 600 610 (Kg/cm 2 ) t/day 86 87 88 89 90 91 92 0 630 630 630 630 630 630 630 10 640 650 650 640 650 650 650 30 650 650 650 640 650 650 650 60 640 610 610 600 610 610 610 (Kg/cm 2 ) As described above, the present hydrolysis stabilizer for an ester-containing resin has an excellent compatibility with the ester group-containing resin and can be added to the resin without causing any trouble when the resin was synthesized and melt-kneaded. Moreover, since the hydrolysis stabilizer has a high molecular weight, it can sufficiently exhibit the hydrolysis stabilizing effect on the resin. The present process for the hydrolysis stabilization of an ester group-containing resin comprises mixing the above-mentioned hydrolysis stabilizer with the ester group-containing resin, and hence, can be easily carried out.

Claims: A hydrolysis stabilizer for an ester group-containing resin, which comprises as a main component a carbodiimide having at least two carbodiimide groups in the molecule and resulting from 4,4' - dicyclohexylmethane diisocyanate represented by the formula (I): or isophorone diisocyanate represented by the formula (II): or a mixture of 4,4'-dicyclohexylmethane diisocyante of the fromula (I) and isophorone diisocyanate of formula (II), wherein the carbodiimide is end-blocked with a carboxyl acid, an acid anhydride or a monoisocyanate. A hydrolysis stabilizer for an ester group-containing resin according to claim 1, wherein the carbodiimide has an average degree of polymerization of 2 to 30. A hydrolysis stabilizer for an ester group-containing resin, which comprises as a main component a carbodiimide having at least two carbodiimide groups in the molecule and resulting from a mixture of tetramethylxylylene diisocyanate represented by the fromula (III): with 4,4' ― dicyclohexylmethane diisocyanate represented by the formula (I): or isophorone diisocyanate represented by the formula (II): or a mixture of 4,4' - dicyclohexylmethane diisocyanate of the formula (I) and isophorone diisocyanate of the formula (II), wherein the carbodiimide is end-blocked with a carboxylic acid, an acid anhydride or a monoisocyanate. A hydrolysis stabilizer for an ester group-containing resin according to claim 3 wherein the carbodiimide has an average degree of polymerization of 2 to 30. A process for the hydrolysis stabilization of an ester group-containing resin, which comprises mixing the ester group-containing resin with a carbodiimide having at least two carbodiimide groups in the molecule and resulting from 4,4' - dicyclohexylmethane diisocyanate represented by the formula (I) or isophorone diisocyanate represented by the formula (II): or a mixture of 4,4' - dicyclohexylmethane diisocyanate of the formula (I) and isophorone diisocyanate of the formula (II), wherein the carbodiimide is end-blocked with a carboxylic acid, an acid anhydride or a monoisocyanate. A process for the hydrolysis stabilization of an ester group-containing resin according to claim 5, wherein the carbodiimide has an average degree of polymerization of 2 to 30. A process for the hydrolysis stabilization of an ester group-containing resin which comprises mixing the ester group-containing resin with a carbodiimide having at least two carbodiimide groups in the molecule and resulting from a mixture of tetramethylxylylene diisocyanate represented by the formula (III): with 4,4' ― dicyclohexylmethane diisocyanate represented by the formula (I): or isophorone diisocyanate represented by the formula (II): or a mixture of 4,4'-dicyclohexylmethane diisocyanate of the formula (I) and isophorone diisocyanate of the formula (II), wherein the carbodiimide is end-blocked with a carboxylic acid, an acid anhydride or a monoisocyanate. A process for the hydrolysis stabilization of an ester group-containing resin according to claim 7, wherein the carbodiimide has an average degree of polymerization of 2 to 30.

Inventors: HORIE NAOFUMI, IMASHIRO YASUO, TAKAHASHI IKUO, YAMANE TAKESHI, HORIE, NAOFUMI, IMASHIRO, YASUO, TAKAHASHI, IKUO, YAMANE, TAKESHI, Horie, Naofumi, Nisshinbo Industries Inc., Imashiro, Yasuo, Nisshinbo Industries Inc., Takahashi, Ikuo, Nisshinbo Industries Inc., Yamane, Takeshi, Nisshinbo Industries Inc.
Applicants: NISSHIN SPINNING, NISSHINBO INDUSTRIES, INC.
Application year: 1997
Main classification: C08L75
IPC codes: C08L79, C08K5, C08L67, C08L75