JPH05295067A - Polyurethane elastomer and its production - Google Patents

Abstract

PURPOSE:To produce the subject elastomer excellent in mechanical properties with an excellent workability without causing a problem about the safety and the sanitation by making a specified diol and a specified triol as curing agents react with a polyisocyanate and a polyol. CONSTITUTION:The objective elastomer is obtained by making curing agents composed of (B) a diol (preferably p-xylylene glycol, etc.) of the formula (A1 and A2 are each a bond,-O-, etc.; R1 and R2 are each a 1 to 6C alkylene; X1 and X2 are each H or a hydroxyalkyl) and (C) a triol (e.g. trimethylol propane) having 60 to 500 hydroxyl equivalent react on (A) a polyisocyanate (preferably 4,4'-diphenylmethane diisocyanate) and a polyol (preferably polypropylene glycol or polytetramethylene ether glycol) or a terminal NCO group-containing prepolymer synthesized from those compounds.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyurethane elastomer having excellent mechanical strength and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Polyurethane elastomers are widely used in various industrial rolls, belts, office equipment parts, etc. due to their excellent mechanical, thermal and chemical properties. As a method of producing such a polyurethane elastomer, there is a method of reacting a prepolymer having an isocyanate group at an end obtained by reacting an excess polyisocyanate with a polyol, and a curing agent. 4,4'-methylenebis-2-chloroaniline (hereinafter referred to as MOCA) is widely used as the curing agent. Polyurethane elastomers produced using such MOCA as a curing agent show excellent mechanical and thermal properties, but in recent years, the carcinogenicity of MOCA has been a concern, and its use due to occupational health and safety problems. Has come to be restricted. Under these circumstances, MOC
Various curing agents replacing A have been studied, and for example, bis (β-hydroxyethoxy) benzene (hereinafter, BHEB
Called. ), P-xylylene glycol (hereinafter P-
It is called XG. ), Bis (β-hydroxyethyl) terephthalate (hereinafter referred to as BHET), and the like have been proposed. However, the melting point of these compounds is higher than the melting point of MOCA (about 98 ° C.), and when the compound is mixed with the prepolymer, crystals of the curing agent may precipitate, resulting in poor mixing. In order to prevent it, each of the above components must be kept at a high temperature, which causes a problem in workability. Further, the elastomer obtained by using these curing agents has high hardness, and it is difficult to obtain a rubber elastic body having appropriate elasticity. Further, in order to solve the problem of workability of the above curing agent, it is proposed to use, for example, a mixture of BHEB and 1,4-butanediol (hereinafter referred to as 1,4-BG) as a curing agent. However, in such a production method, the mechanical properties of the polyurethane elastomer are deteriorated, and the problem still remains. Furthermore, for example, B
It is considered that a low molecular weight triol such as trimethylolpropane (hereinafter referred to as TMP) is mixed with HEB or the like and used as a curing agent, but as a result of the study by the present inventors, it was obtained by adding TMP. Tear strength of polyurethane elastomers decreases, and tangent loss (tan
It became clear that the dynamic performance such as roll running durability deteriorates as the value of δ) increases. Based on the above findings, the inventors of the present invention have conducted extensive studies and as a result, reacted a polyisocyanate and a polyol or a prepolymer obtained by reacting them with a diol such as BHEB and a triol having a hydroxyl equivalent of 60 to 500. As a result, it was found that a polyurethane elastomer having excellent mechanical properties can be produced with no problems in safety and hygiene and workability, and as a result of further studies, the present invention has been completed.

[0003]

Means for Solving the Problems That is, the present invention comprises (1) a polyisocyanate and a polyol, or a prepolymer having an isocyanate group at the terminal obtained by reacting them (hereinafter referred to as component (1)), 2)
General formula

[Chemical 4] (In the formula, A ₁ and A ₂ are the same or different and each is a bond, —O
-Or -CO.O-, R ₁ and R ₂ are the same or different and represent alkylene having 1 to 6 carbon atoms, and X ₁ and X ₂ are the same or different and represent H or hydroxyalkyl. ) (Hereinafter, referred to as diol (2)) and (3) a triol having a hydroxyl equivalent of 60 to 500 (hereinafter, referred to as triol (3)) are reacted with each other, A curing agent composition for a polyurethane elastomer containing the polyurethane elastomer, the diol (2) and the triol (3). In the present invention, a polyisocyanate, a polyol and a curing agent are mixed and reacted at the same time, a so-called one-shot method, and a prepolymer having an isocyanate group at the terminal obtained by previously reacting a polyisocyanate and a polyol and a curing agent. The so-called prepolymer method of reacting is used, but the prepolymer method is particularly preferably used.

The polyisocyanate used in the present invention is not particularly limited, and for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and a mixture thereof (for example, a weight ratio of 80/20,
65/35), 4,4′-diphenylmethane diisocyanate, m-phenylene diisocyanate, p-
Phenylene diisocyanate, xylylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate ester, 1,4-cyclohexylene diisocyanate, 3,
3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, tetramethylxylylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1 , 5-naphthalene diisocyanate,
Aromatic, aromatic alicyclic, aliphatic and alicyclic polyisocyanates such as 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, etc. Examples include polyisocyanates that are usually used in the production of polyurethane resins, such as carbodiimide modified products, biuret modified products, dimers, and trimers, and these may be used alone or as a mixture of two or more kinds. Of these,
Preferably, an aliphatic polyisocyanate or an aromatic polyisocyanate is used, and in particular, from the viewpoint of mechanical strength of the resulting polyurethane elastomer, an aromatic polyisocyanate is preferable, and among them, 4,4′-diphenylmethane diisocyanate is particularly preferable. It is preferably used.

As the polyol used in the present invention,
For example, ethylene glycol, diethylene glycol,
Low molecular weight diols such as triethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexanediol, diethylene glycol and dipropylene glycol,
Polyether polyol obtained by adding one or more kinds of alkylene oxide such as ethylene oxide, propylene oxide and butylene oxide and cyclic ether such as tetrahydrofuran to one or more kinds of the low molecular weight diol, One or more low molecular weight diols, malonic acid, maleic acid,
Polyester polyol obtained by condensing one or more dibasic acids such as succinic acid, adipic acid, tartaric acid, pimelic acid, sebacic acid, oxalic acid, phthalic acid, terephthalic acid and isophthalic acid, ε-caprolactone , Polyols obtained by ring-opening cyclic ester such as γ-valerolactone, polybutadiene diol having hydroxyl group at the terminal, and other polyols usually used in the production of polyurethane resin can be mentioned. Used as a mixture of two or more species. Of these, polyester diols such as polypropylene glycol, polytetramethylene ether glycol, polyethylene adipate and polypropylene adipate, polyester polyols obtained by ring-opening ε-caprolactone, and mixtures of these with the aforementioned low molecular weight diols are preferably used. .. The molecular weight of these polyols is usually about 300 to 10,000, preferably about 350 to 5,000.

The prepolymer having an isocyanate group at the terminal used in the present invention is produced by reacting the above polyol with an excess amount of the above polyisocyanate. For example, a polyisocyanate is stirred under a nitrogen stream, and a polyol is added thereto at a reaction temperature of 85.
A prepolymer having an isocyanate group at the terminal is obtained by gradually adding while maintaining the temperature at a temperature not exceeding 50 ° C. and then performing a reaction at about 80 ° C. for about 1 to several hours. If necessary, the unreacted polyisocyanate monomer may be removed from the reaction solution by using a means such as distillation or extraction. Usually, the use ratio of the polyisocyanate and the polyol used as the component (1) and the use ratio of the polyisocyanate and the polyol used for producing the prepolymer are all 1.3 to NCO / OH equivalent ratio. It is about 3.0, preferably about 1.8 to 2.2. In the production method of the present invention, a curing agent composition for a polyurethane elastomer containing a diol (2) and a triol (3) is used as a curing agent to react with the component (1). The diol (2) used in the present invention is represented by the following general formula.

[Chemical 5] (In the formula, A ₁ and A ₂ are the same or different and each is a bond, —O
-Or -COO-, R ₁ and R ₂ are the same or different and represent alkylene having 1 to 6 carbon atoms, and X ₁ and X ₂ are the same or different and represent H or hydroxyalkyl. In the above formula, the alkylene having 1 to 6 carbon atoms represented by R ₁ and R ₂ is a linear or branched one, and specific examples thereof include methylene, ethylene, trimethylene, tetramethylene, pentamethylene. Methylene, hexamethylene, ethylethylene, propylene and the like can be mentioned, and among these, those having 1 to 4 carbon atoms are preferable. The hydroxyalkyl represented by X ₁ and X ₂ is a alkylene to which a hydroxyl group is bonded, and the alkylene portion is a straight or branched chain having 1 to 6 carbon atoms. Specific examples of the alkylene include the alkylenes represented by R ₁ and R ₂ described above.

Specific examples of the diol include, for example,
1,2-, 1,3-, 1,4-bis (β-hydroxyethyl) benzene and mixtures thereof, 1,2-, 1,3
-, 1,4-bis (β-hydroxypropyl) benzene and mixtures thereof, 1- (β-hydroxypropyl) -2- (β-hydroxyethyl) benzene, 1-
(Β-Hydroxypropyl) -3- (β-hydroxyethyl) benzene, 1- (β-hydroxypropyl)-
4- (β-hydroxyethyl) benzene and a mixture thereof, ο-, m-, p-xylylene glycol and a mixture thereof, one or more of bifunctional phenols such as resorcinol and hydroquinone, and ethylene oxide , Propylene oxide, butylene oxide, and other addition polymers obtained by adding one or more alkylene oxides, terephthalic acid, isophthalic acid, phthalic acid, 4,4'-, 2,4- and 2,2 It is obtained by dehydration condensation of one or more aromatic dibasic acids such as'-biphenylcarboxylic acid and one or more low molecular weight diols used as the component (1) having 1 to 10 carbon atoms. A compound etc. are mentioned. These diols are used alone or as a mixture of two or more kinds. Of these, those having a terminal hydroxy substituent at the para position among bis (β-hydroxyethoxy) benzene, bis (β-hydroxyethyl) terephthalate, xylylene glycol, bis (β-hydroxyethyl) benzene and the like are preferable. Is used.

The triol (3) used in the present invention is a triol having a hydroxyl equivalent of 60 to 500, preferably 60 to 300, and more preferably 60 to 200. If the hydroxyl equivalent is less than 60, the resulting polyurethane elastomer may have a decreased tear strength or dynamic performance, and if it exceeds 500, the mechanical strength (especially tensile strength) of the polyurethane elastomer may be reduced. Etc.) may decrease. Specific examples of the triol (3) include, for example, one or more low molecular weight triols such as trimethylolpropane, glycerin and triisopropanolamine, and one alkylene oxide such as ethylene oxide, propylene oxide and butylene oxide. Alternatively, a trifunctional polyether triol obtained by randomly or block-wise addition of two or more kinds, one or more kinds of the above low molecular weight triols, and one of cyclic esters such as ε-caprolactone and γ-valerolactone. Or a trifunctional polyester triol obtained by adding two or more kinds thereof, a hydroxyl group-containing fatty acid ester which is a condensate of one or more kinds of the above low molecular weight triols and one or more kinds of hydroxyl group-containing fatty acids (For example, castor oil) These are used alone or as a mixture of two or more kinds. The diol (2) and triol (3) in the present invention are preferably used together in a weight ratio of 1: 0.05 to 1.5, more preferably 1: 0.1.
It is used together at a ratio in the range of to 1.0. If the proportion of the diol is higher than this range, the melting point of the curing agent composition will not be sufficiently lowered, and problems may occur in workability.
On the other hand, if the proportion of triol is higher than this range,
The mechanical properties (for example, tensile strength, tear strength, etc.) of the obtained polyurethane elastomer may deteriorate. The melting point of the curing agent composition is preferably 105 ° C. or lower, more preferably 100 ° C. or lower, in view of the preheating temperature of the prepolymer and workability.

In addition to the diol (2) and the triol (3), the curing agent composition of the present invention contains 1 or more other divalent or higher valent polyols and divalent or higher valent polyamines as long as the characteristics of the present invention are not deteriorated. One kind or two or more kinds can be blended. Examples of such polyols include diols having 1 to 10 carbon atoms among low molecular weight diols used as the component (1), low molecular weight triols such as trimethylolpropane, glycerin, and triisopropanolamine. Examples of polyamines include 1,2-ethane-bis- (ο-chloraniline),
1,3-propane-bis- (ο-chloroaniline), trimethylene glycol-di-p-aminobenzoate,
4-methyl-3,5-diaminobenzoic acid methyl ester, 4,4'-methylenedianthranilic acid ester (eg, dimethyl form, diethyl form, diisopropyl form, etc.),
Bis (2-methyl-4-aminophenyl) methane, bis (3-methyl-4-aminophenyl) methane, bis (2
Examples include conventionally known MOCA substitute amines or polyamines having no suspected carcinogenicity, such as -ethyl-4-aminophenyl) methane, bis (3-ethyl-4-aminophenyl) methane, and 4,4'-diaminodiphenylmethane. .. The total amount of the diol (2) and the triol (3) contained in the curing agent composition for a polyurethane elastomer of the present invention is about 60% by weight or more, preferably about 80% by weight or more, based on the entire curing agent composition. Preferably 100
% By weight. Regarding the reaction ratio of the component (1), the diol (2) and the triol (3) used in the present invention, the hydroxyl group and the isocyanate group in all the components are OH / NCO (equivalent ratio) = 0.8 to 1.20. The ratio is preferably 0.9 to 1.10. If this ratio deviates from the above range, the mechanical strength of the obtained polyurethane elastomer may decrease.

In the production of the polyurethane elastomer of the present invention, if necessary, a curing catalyst and various additives such as an antioxidant, an ultraviolet absorber, a coloring inhibitor, a hydrolysis inhibitor, an antifungal agent, a flame retardant, A filler, a filler (for example, calcium carbonate, silica, talc, etc.), a plasticizer (for example, dioctyl phthalate, etc.), an organic solvent, a colorant and the like can also be appropriately used. Examples of the curing catalyst include organic metal salts such as dibutyltin dilaurylate and stannas octoate; quaternary ammonium salts such as triethylbenzylammonium chloride and tetramethylammonium chloride; triethylamine, tripropylamine, tributylamine, benzyldimethylamine. , Tertiary amines such as N-ethylmorpholine, 2-methylimidazole and 2-methyl-4-ethylimidazole; halogenated metals such as aluminum chloride, ferric chloride, boron trifluoride and zinc chloride; adipic acid, Examples thereof include organic acids such as salicylic acid and benzoic acid and the like, and curing catalysts usually used in the production of polyurethane resins. The amount of the curing catalyst used is appropriately selected, but is usually about 5% by weight or less, preferably 0.01 to
It is about 1% by weight. In the present invention, excess polyisocyanate and polyol, or a prepolymer having an isocyanate at the end obtained by reacting them, that is, component (1) is heated in advance and cured by heating and melting separately. By adding the agent composition, stirring and mixing to obtain a molten mixture, and if necessary defoaming under reduced pressure, injecting this into a mold, heating at about 100 to 140 ° C., curing and demolding A polyurethane elastomer is obtained. The curing catalyst and additives can be added at an appropriate stage before curing, for example, a prepolymer production process, a heating and melting process of the curing agent composition, and a mixing process of the component (1) and the curing agent composition. ..

In the present invention, by using the diol (2) and the triol (3) together as a curing agent, the melting point of the curing agent is lower than that when the diol (2) is used alone. Therefore, in the manufacturing process, the preheating of the component (1) and the melting of the curing agent can be performed at a relatively low temperature.
Specifically, the preheating temperature of the component (1) and the melting temperature of the curing agent are appropriately set according to the melting points, the softening points and the like of the component (1) and the curing agent. For example, the preheating temperature of the component (1) Is about 80 to 120 ° C., preferably about 80 to 100 ° C.,
The melting temperature of the curing agent is about 90 to 130 ° C., preferably 9
It is about 0 to 120 ° C., and can be preheated and melted at a temperature about 5 to 30 ° C. lower than when the diol (2) is used alone. Further, prior to the above step, it is preferable to preheat the component mold to, for example, about 100 to 140 ° C. in order to improve the uniformity of the polyurethane elastomer. Polyurethane elastomer is usually 1
After being cured by heating for several hours to several hours, it can be released from the mold, and thereafter, a curing reaction is further performed at the above curing temperature for about 4 to 24 hours, and if necessary, it may be aged at room temperature for about 3 to 7 days. it can. The polyurethane elastomer obtained by the present invention has excellent mechanical, thermal and chemical properties, and is widely and advantageously used in the field of the market where MOCA-curable polyurethane elastomers are currently used. Further, the polyurethane elastomer obtained by the present invention has a small tan δ value and, at the same time, a very small loss compliance (J ″) value,
Since it has excellent dynamic performance, it is particularly advantageously used in fields requiring dynamic performance such as various industrial rolls and belts.

[0012]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these Examples. In the examples,
"Parts" and "%" are based on weight. Example 1 [Production of prepolymer] Polytetramethylene ether glycol having an average molecular weight of 1000 (manufactured by Mitsubishi Kasei Co., PTM)
50 parts of 4,4′-diphenylmethane diisocyanate was added to 100 parts of EG1000), and the reaction was carried out while stirring at 80 ° C. for 4 hours under a nitrogen stream to obtain a prepolymer having an isocyanate group content of 5.6% and a viscosity of 1700 cps (80 ° C.). polymer
(A) was obtained. [Production of Polyurethane Elastomer] 100 parts of the prepolymer (A) obtained by the above method was preheated to 100 ° C., and this was mixed with 70 parts of bis (β-hydroxyethoxy) benzene (BHEB) and a hydroxyl equivalent of 130 parts. 30 parts of methylol propane-based trifunctional polyether polyol (ACTCOL IR-96, manufactured by Takeda Pharmaceutical Co., Ltd.) was mixed with 13.5 parts of a curing agent that had been melt-mixed at 120 ° C. in advance, and the mixture was mixed for 1 minute. It was stirred. After degassing for 1 minute under reduced pressure, 1
It was poured into a stainless steel mold preheated to 10 ° C. and cured at the same temperature for 20 hours to obtain a polyurethane elastomer. The obtained polyurethane elastomer showed good rubber elasticity at room temperature.

Examples 2 to 7 By using the prepolymer (A) obtained in Example 1 and the curing agent having the composition shown in [Table 1], a polyurethane elastomer was obtained in the same manner as in Example 1. Comparative Example 1 In the same manner as in Example 1 except that the prepolymer (A) obtained in Example 1 and the curing agent having the composition shown in [Table 2] were used and preheating of the prepolymer was 120 ° C. A polyurethane elastomer was obtained. Further, when preheating of the prepolymer (A) was set to 100 ° C. as in the examples, BHEB crystals were precipitated during mixing with the curing agent, resulting in poor mixing, and a polyurethane elastomer available for practical use was obtained. I couldn't do it. Comparative Example 2 Similar to Example 1 except that the prepolymer (A) obtained in Example 1 and the curing agent having the composition shown in [Table 2] were used and the preheating temperature of the prepolymer was 120 ° C. A polyurethane elastomer was obtained by the method. Further, when the preheating temperature of the prepolymer is 100 ° C. as in the example,
Crystals of p-xylylene glycol (P-XG) were precipitated during mixing, resulting in poor mixing, and a polyurethane elastomer that could be put to practical use could not be obtained. Comparative Examples 3 and 4 Using the prepolymer (A) obtained in Example 1 and the curing agent having the composition shown in [Table 2], a polyurethane elastomer was obtained in the same manner as in Example 1.

Reference Example 1 Commercially available prepolymer having an isocyanate group at the end (Takenate L-2710, isocyanate group content 4.
2%, 100 parts by Takeda Pharmaceutical Co., Ltd., and 4,4'-methylenebis-2-chloroaniline (MOC) as a curing agent.
A polyurethane elastomer was obtained in the same manner as in Example 1 except that 12 parts of A) was used. The results obtained by measuring the various physical properties of the polyurethane elastomers obtained in the first reaction of Examples 1 to 8 and Comparative Examples 1 to 4 and Reference Example 1 are also shown in [Table 1] and [Table 2].

[Table 1]

[Table 2] Note) 1) Polycaprolactone-based trifunctional polyester polyol, hydroxyl equivalent 130, manufactured by Daicel, Inc. 2) Polycaprolactone-based trifunctional polyester polyol, hydroxyl equivalent 184, manufactured by Daicel, 3) According to JISK6301, using A-type spring hardness tester. Measurement 4) According to JISK6301, measured with No. 3 dumbbell 5) According to JISK6301, measured with B-type dumbbell 6) 100 ° C tan δ measured with a viscoelastic spectrometer at a frequency of 10 Hz and a heating rate of 5 ° C / min Indicates. 7) The line pressure when rotating at a peripheral speed of 300 m / min with a roll running test machine and increasing the line pressure from 60 kg / cm by 20 kg / cm every hour and bursting is shown. 8) Measured with a viscoelastic spectrometer. The J ″ value at a temperature obtained by adding 100 ° C. to the glass transition temperature (Tg) is shown. From [Table 1] and [Table 2], the curing agent composition of the present invention containing a diol and a triol (for example, BHEB +
ACTCOL IR-96, P-XG + ACTCOL IR
-96, BHEB + Plaxel 305, BHEB + Plaxel 308 are each diol (for example, BH).
(EB, P-XG) alone has a lower melting point than that of the curing agent, and therefore, even if the preheating temperature of the prepolymer is lowered, crystals do not precipitate, so that it is clear that workability is excellent. .. Further, the polyurethane elastomer obtained by using the curing agent composition of the present invention has mechanical properties such as tensile strength and tear strength as compared with the case of using a mixture of BHEB and 1,4-BG and a mixture of BHEB and TMP. It is clear that the tan δ value at 100 ° C. is small and the durability in the roll running test is also excellent.

[0015]

The curing agent composition for polyurethane elastomers containing the specific diol (2) and the triol (3) having a hydroxyl equivalent of 60 to 500 of the present invention is a curing agent containing only the diol (2). Has a lower melting point,
It is not necessary to raise the preheating temperature of each component when producing a polyurethane elastomer, and it is excellent in workability,
Further, according to the method for producing a polyurethane elastomer of the present invention using the same, a polyurethane elastomer having excellent mechanical properties such as tensile strength and tear strength can be obtained. Therefore, for example, various industrial rolls, belts, office equipment parts, etc. It is widely and advantageously used for the production of elastic bodies in the fields requiring excellent mechanical, thermal and chemical properties.

Claims (6)

[Claims] 1. A polyisocyanate and a polyol, or a prepolymer having an isocyanate group at a terminal obtained by reacting them, and (2) a compound represented by the general formula: (In the formula, A ₁ and A ₂ are the same or different and each is a bond, —O
-Or -COO-, R ₁ and R ₂ are the same or different and represent alkylene having 1 to 6 carbon atoms, and X ₁ and X ₂ are the same or different and represent H or hydroxyalkyl. ) And a (3) hydroxyl group equivalent triol having a hydroxyl group equivalent of 60 to 500 are reacted with each other. 2. The method for producing a polyurethane elastomer according to claim 1, wherein the triol is a polyether triol obtained by randomly or block-wise addition of trimethylolpropane and alkylene oxide. 3. The method for producing a polyurethane elastomer according to claim 1, wherein the weight ratio of the diol to the triol is 1: 0.05 to 1.5. 4. A polyisocyanate and a polyol, or a prepolymer having an isocyanate group at a terminal obtained by reacting them, and (2) a compound represented by the general formula: (In the formula, A ₁ and A ₂ are the same or different and each is a bond, —O
-Or -COO-, R ₁ and R ₂ are the same or different and represent alkylene having 1 to 6 carbon atoms, and X ₁ and X ₂ are the same or different and represent H or hydroxyalkyl. ) A polyurethane elastomer obtained by reacting a diol represented by the formula (4) and a triol (3) having a hydroxyl group equivalent of 60 to 500. 5. A general formula: (In the formula, A ₁ and A ₂ are the same or different and each is a bond, —O
-Or -COO-, R ₁ and R ₂ are the same or different and represent alkylene having 1 to 6 carbon atoms, and X ₁ and X ₂ are the same or different and represent H or hydroxyalkyl. ) And a curing agent composition for a polyurethane elastomer containing a diol and a triol having a hydroxyl equivalent of 60 to 500. 6. A weight ratio of diol and triol of 1: 0.
The curing agent composition according to claim 5, which is contained in a proportion of 05 to 1.5.