JP2023100865A - Thermosetting polyurethane elastomer-forming composition, and industrial machine component using the same - Google Patents

Abstract

To provide a thermosetting polyurethane elastomer-forming composition suppressed in reduction of mechanical strength under a high temperature, and having excellent heat resistance and durability while using a raw material which is inexpensive, and high safety, and an industrial machine component using the same.SOLUTION: A thermosetting polyurethane elastomer-forming composition includes: an isocyanate group-terminated urethane prepolymer composed of diphenylmethane diisocyanate and a polyol having an ether unit or an ester unit; and a hydroxyl group-terminated curing agent composed of ethylene glycol and a triol having an ester unit or an ether unit and a number average molecular weight of 300-1,000. The content of the ethylene glycol is 0.7-1.3 mmol/g to a total amount of the thermosetting polyurethane elastomer-forming composition, and the content of the triol is 0.01-0.1 mmol/g to a total amount of the thermosetting polyurethane elastomer-forming composition.SELECTED DRAWING: None

Description

The present invention relates to a thermosetting polyurethane elastomer-forming composition and industrial machine parts using the same.

Thermosetting polyurethane elastomers have high modulus, high breaking strength, low wear, and low strain, so they have very high durability and are suitably used as components of industrial machinery.
As a component of the thermosetting polyurethane elastomer-forming composition, 4,4'-diamino-3,3'-dichlorodiphenylmethane (hereinafter abbreviated as "MOCA"), which is an amino terminal curing agent whose amino group acts as an active hydrogen group. ) are widely used. However, MOCA has been pointed out to be carcinogenic.

Therefore, Patent Document 1 describes trimethylene-bis(4-aminobenzoate), polytetramethylene oxide-di-P-aminobenzoate, 4,4-diamino-3,3, which have extremely low carcinogenic risk, as amino group terminal curing agents. -diethyl-5,5-dimethyldiphenylmethane, 4,4-methylenebis-(2,6-diethylaniline).

JP 2007-146093 A

However, in the thermosetting polyurethane elastomer-forming composition according to Patent Document 1, the viscosity of the obtained thermosetting polyurethane elastomer is higher than that containing MOCA, the dynamic heat generation amount is large, and the durability is poor. Not enough. In addition, the composition for forming a thermosetting polyurethane elastomer according to Patent Document 1 is expensive, so it is currently not widely used.
Accordingly, one aspect of the present invention is a thermosetting polyurethane elastomer-forming composition that suppresses a decrease in mechanical strength at high temperatures and has excellent heat resistance and durability while using inexpensive and highly safe raw materials. is directed to the provision of Another aspect of the present invention is to provide an industrial machine part that uses the thermosetting polyurethane elastomer-forming composition to suppress a decrease in mechanical strength at high temperatures and has excellent heat resistance and durability. It is

One aspect of the present invention is shown in (1) to (3) below.
(1): A thermosetting polyurethane elastomer-forming composition comprising an isocyanate group-terminated urethane prepolymer (A) and a hydroxyl group-terminated curing agent (B),
The isocyanate group-terminated urethane prepolymer (A) contains at least
diphenylmethane diisocyanate (A1); and
and a polyol (A2) having an ether unit,
The hydroxyl group terminal curing agent (B) contains at least
ethylene glycol (B1);
and a triol (B2) having a number average molecular weight of 300 or more and 1000 or less having an ester unit,
The content of the ethylene glycol (B1) is 0.7 mmol/g or more and 1.3 mmol/g or less with respect to the total amount of the thermosetting polyurethane elastomer-forming composition,
A thermosetting polyurethane elastomer-forming composition, wherein the content of the triol (B2) is 0.01 mmol/g or more and 0.1 mmol/g or less relative to the total amount of the thermosetting polyurethane elastomer-forming composition.

(2): A thermosetting polyurethane elastomer-forming composition comprising an isocyanate group-terminated urethane prepolymer (A) and a hydroxyl group-terminated curing agent (B),
The isocyanate group-terminated urethane prepolymer (A) contains at least
diphenylmethane diisocyanate (A1); and
and a polyol (A3) having an ester unit,
The hydroxyl group terminal curing agent (B) contains at least
ethylene glycol (B1);
and a triol (B3) having an ether unit and a number average molecular weight of 300 or more and 1000 or less,
The content of the ethylene glycol (B1) is 0.7 mmol/g or more and 1.3 mmol/g or less with respect to the total amount of the thermosetting polyurethane elastomer-forming composition,
A thermosetting polyurethane elastomer-forming composition, wherein the content of the triol (B3) is 0.01 mmol/g or more and 0.1 mmol/g or less relative to the total amount of the thermosetting polyurethane elastomer-forming composition.

(3): A cured product obtained by curing the thermosetting polyurethane elastomer-forming composition described in (1) or (2) at 90° C. or higher and 150° C. or lower has a JIS-A hardness of 80 or higher and 98. and a storage modulus (E′) at 100° C. of 40 MPa or more.

One aspect of the present invention is to provide a thermosetting polyurethane elastomer-forming composition that suppresses a decrease in mechanical strength at high temperatures and has excellent heat resistance and durability while using inexpensive and highly safe raw materials. can provide. Another aspect of the present invention is to provide an industrial machine part that uses the thermosetting polyurethane elastomer-forming composition to suppress a decrease in mechanical strength at high temperatures and has excellent heat resistance and durability. can do.

[Thermosetting polyurethane elastomer-forming composition]
A thermosetting polyurethane elastomer-forming composition according to one aspect of the present invention comprises an isocyanate group-terminated urethane prepolymer (A) and a hydroxyl group-terminated curing agent (B), and has the following (i) or (ii): Fulfill.

(i): The isocyanate group-terminated urethane prepolymer (A) comprises at least diphenylmethane diisocyanate (A1) and a polyol (A2) having an ether unit, and the hydroxyl group-terminated curing agent (B) comprises at least ethylene glycol. (B1) and a triol (B2) having a number average molecular weight of 300 or more and 1000 or less having an ester unit, and the content of ethylene glycol (B1) is 0.7 mmol/g or more and 1.3 mmol/g or less, and the content of the triol (B2) is 0.01 mmol/g or more and 0.1 mmol/g or less with respect to the total amount of the thermosetting polyurethane elastomer-forming composition; is.

(ii): The isocyanate group-terminated urethane prepolymer (A) comprises at least diphenylmethane diisocyanate (A1) and an ester unit-containing polyol (A3), and the hydroxyl group-terminated curing agent (B) comprises at least ethylene glycol. (B1) and a triol (B3) having an ether unit and having a number average molecular weight of 300 or more and 1000 or less, and the content of ethylene glycol (B1) is 0.7 mmol/g or more and 1.3 mmol/g or less, and the content of the triol (B3) is 0.01 mmol/g or more and 0.1 mmol/g or less with respect to the total amount of the thermosetting polyurethane elastomer-forming composition; is.

The thermosetting polyurethane elastomer-forming composition according to this embodiment increases the cohesion of the hard segment composed of diphenylmethane diisocyanate (A1) and ethylene glycol (B1), thereby increasing the mechanical strength of the cured product at high temperatures. can suppress the decrease in In order to increase the cohesive strength of the hard segment more efficiently, it is necessary to deteriorate the compatibility of the hard segment with the soft segment. Therefore, in the case of the above (i), that is, when using an isocyanate group-terminated urethane prepolymer (A) composed of diphenylmethane diisocyanate (A1) and a polyol (A2) having an ether unit, the number average molecular weight having an ester unit of 300 or more It is preferable to use a triol (B2) having a molecular weight of 1000 or less as a component of the hydroxyl terminal curing agent (B). In the case of the above (ii), that is, when using an isocyanate group-terminated urethane prepolymer (A) composed of diphenylmethane diisocyanate (A1) and a polyol (A3) having an ester unit, the number average molecular weight having an ether unit of 300 or more It is preferable to use a triol (B3) having a molecular weight of 1000 or less as a constituent component of the hydroxyl terminal curing agent (B).

Next, the constituent components of the thermosetting polyurethane elastomer-forming composition according to this embodiment will be described in more detail.

<Isocyanate group-terminated urethane prepolymer (A)>
The isocyanate group-terminated urethane prepolymer (A) consists of diphenylmethane diisocyanate (A1) and a polyol (A2) having an ether unit, or diphenylmethane diisocyanate (A1) and a polyol (A3) having an ester unit, consists of

<<Diphenylmethane diisocyanate (A1)>>
Diphenylmethane diisocyanate (A1) includes 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 2,2'-diphenylmethane diisocyanate, and one or more of these can be used. Diphenylmethane diisocyanate (A1) is not particularly limited, but 4,4'-diphenylmethane diisocyanate is particularly preferred from the viewpoint of suppressing deterioration of mechanical properties at high temperatures.
Diphenylmethane diisocyanate (A1) can also be used in combination with other polyisocyanates. However, diphenylmethane diisocyanate (A1) is preferably contained in an amount of 60% by mass or more, more preferably 80% by mass or more, relative to the total amount of isocyanate in the isocyanate group-terminated urethane prepolymer (A). .

<<Other polyisocyanates>>
Other polyisocyanates include, for example, hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, cyclohexyl diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated trimethylxylylene diisocyanate, 2-methylpentane-1, Aliphatic and alicyclic diisocyanates such as 5-diisocyanate, 3-methylpentane-1,5-diisocyanate, 2,4,4-trimethylhexamethylene-1,6-diisocyanate; 4,4′-diphenyldimethylmethane diisocyanate, Aromatic diisocyanates such as 4,4′-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, paraphenylene diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate; ortho-xylylene diisocyanate, meta-xylylene diisocyanate Non-yellowing diisocyanates such as isocyanate, paraxylylene diisocyanate, tetramethylxylylene diisocyanate; urethane modified products thereof, urea modified products, carbodiimide modified products, uretonimine modified products, uretdione modified products, isocyanurate modified products, allophanate modified products; etc.

<<polyol (A2) having an ether unit>>
The polyol (A2) having an ether unit is not particularly limited, but from the viewpoint of mechanical properties and glass transition temperature, at least one selected from polyols having an average functional group number of 2 to 3 and a number average molecular weight of 250 to 5000 Kinds are preferred.
Specific examples of the polyol (A2) having an ether unit include the following polyether polyols (A2-1) and (A2-2).

(A2-1): ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol , 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol , cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc. Polyols; Low-molecular-weight polyamines such as ethylenediamine, propylenediamine, toluenediamine, metaphenylenediamine, diphenylmethanediamine, and xylylenediamine; starting compounds having two or more, preferably two to three, active hydrogen groups such as Polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide as agents.
(A2-2): alkyl glycidyl ethers such as methyl glycidyl ether; aryl glycidyl ethers such as phenyl glycidyl ether; cyclic ether monomers such as tetrahydrofuran; and polyether polyols obtained by ring-opening polymerization.

In addition, the polyol (A2) having an ether unit is polyolefin polyol, acrylic polyol, silicone polyol, castor oil-based polyol, fluorine-based polyol, monomer polyol, used alone or in combination of two or more, as long as the performance is not reduced. be able to. These polyols are described later.

<<Polyol (A3) having an ester unit>>
The polyol (A3) having an ester unit is not particularly limited, but from the viewpoint of mechanical properties and glass transition temperature, at least one selected from polyols having an average functional group number of 2 to 3 and a number average molecular weight of 250 to 5000 Kinds are preferred.

Specific examples of the polyol (A3) having an ester unit include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, and suberic acid. , glutaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α,β-diethylsuccinic acid, maleic acid , dicarboxylic acids such as fumaric acid; or their anhydrides; , 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3 - dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis(β -Hydroxyethyl)benzene, xylylene glycol, glycerin, trimethylolpropane, and one or more low-molecular-weight polyols having a molecular weight of 500 or less, such as pentaerythritol, and a polyol obtained from a polycondensation reaction. Polyester-amide polyols obtained by replacing part of the low-molecular-weight polyol with low-molecular-weight polyamines such as hexamethylenediamine, isophoronediamine and monoethanolamine or low-molecular-weight aminoalcohols can also be used.

Also, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,5-pentanediol, 6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane- 1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, glycerin, trimethylolpropane, penta Cyclic esters such as ε-caprolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone and δ-valerolactone using one or more polyols selected from low molecular weight polyols having a molecular weight of 500 or less such as erythritol as an initiator Polycaprolactone polyols obtained by ring-opening addition of can also be used.

A polycarbonate polyol can also be used as the polyol (A3) having an ester unit. Specific examples of polycarbonate polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5 - pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, Neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, glycerin , trimethylolpropane, pentaerythritol and other low-molecular-weight polyols, and dialkyl carbonates such as dimethyl carbonate and diethyl carbonate; alkylene carbonates such as ethylene carbonate and propylene carbonate; diphenyl carbonate, dinaphthyl carbonate and dianthryl carbonate. , diphenanthryl carbonate, diindanyl carbonate, tetrahydronaphthyl carbonate, and other diaryl carbonates;

In addition, the polyol (A3) having an ester unit includes polyolefin polyol, acrylic polyol, silicone polyol, castor oil-based polyol, fluorine-based polyol, and monomer polyol, either alone or in combination of two or more, as long as the performance does not deteriorate. can do. These polyols can also be used in combination with the above-mentioned polyol (A2) having an ether unit, as long as the performance is not lowered.

<<Polyolefin Polyol>>
Specific examples of polyolefin polyols include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene.

<<Acrylic Polyol>>
Examples of acrylic polyols include acrylic acid esters and/or methacrylic acid esters [hereinafter referred to as (meth)acrylic acid esters], acrylic acid hydroxy compounds having one or more hydroxyl groups that can be reactive sites in the molecule, and/or methacrylic acid. A hydroxy compound (hereinafter referred to as a (meth)acrylic acid hydroxy compound) and a polymerization initiator are copolymerized using thermal energy, light energy such as ultraviolet rays or electron beams, and acrylic monomers.

<<<(meth)acrylic acid ester>>>
Specific examples of (meth)acrylic acid esters include alkyl esters having 1 to 20 carbon atoms. Specific examples of such (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and pentyl (meth)acrylate. , hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, etc. (meth) acrylic acid alkyl esters; esters of (meth)acrylic acid with alicyclic alcohols such as cyclohexyl (meth)acrylate; (meth)acrylate allyl esters such as phenyl (meth)acrylate and benzyl (meth)acrylate; can be mentioned. Such (meth)acrylic acid esters can be used alone or in combination of two or more.

<<<(meth)acrylic acid hydroxy compound>>>
(Meth)acrylic acid hydroxy compounds include, for example, those having one or more hydroxyl groups in the molecule that can act as reaction points with polyisocyanates such as diphenylmethane diisocyanate (A1). Specifically, hydroxy acrylic compounds such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 3-hydroxy-2,2-dimethylpropyl acrylate, pentaerythritol triacrylate; 2-hydroxyethyl hydroxy methacrylate compounds such as methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 3-hydroxy-2,2-dimethylpropyl methacrylate, and pentaerythritol trimethacrylate; These hydroxy acrylate compounds and/or hydroxy methacrylate compounds can be used alone or in combination of two or more.

<<<polymerization initiator>>>
The polymerization initiator can include thermal polymerization initiators and photopolymerization initiators, and is appropriately selected depending on the polymerization method.

Examples of thermal polymerization initiators include peroxydicarbonates such as di-2-ethylhexylperoxydicarbonate; t-butyl peroxybenzoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisopropyl carbonate, peroxyesters such as hexylperoxyisopropyl carbonate; ketals; and the like.

Examples of photopolymerization initiators include acetophenone, methoxyacetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, α-hydroxy-α,α'-dimethylacetophenone, Acetophenones such as 2-hydroxy-2-cyclohexylacetophenone, 2-methyl-1[4-(methylthio)phenyl]-2-monfolinopropanone-1; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl butyl ether benzoin ethers such as benzophenone, 2-chlorobenzophenone, p,p'-dichlorobenzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone, 4-(2-hydroxyethoxy)phenyl(2-hydroxy ketones such as 2-propyl)ketone; thioxanthone such as thioxanthone, 2-chlorothioxanthone and 2-methylthioxanthone; phosphine oxides such as bisacylphosphine oxide and benzoylphosphine oxide; ketals such as benzyl dimethyl ketal quinones such as camphane-2,3-dione and phenanthrenequinone;

<<Silicone Polyol>>
Specific examples of silicone polyols include vinyl group-containing silicone compounds obtained by polymerizing γ-methacryloxypropyltrimethoxysilane, etc., and α,ω-dihydroxypolydimethylsiloxane, α, having at least one terminal hydroxyl group in the molecule. , and ω-dihydroxypolydiphenylsiloxane.

<<castor oil-based polyol>>
Specific examples of castor oil-based polyols include, for example, linear or branched polyester polyols obtained by reacting castor oil fatty acids with polyols. Dehydrated castor oil, partially dehydrated castor oil, and hydrogenated castor oil to which hydrogen is added can also be used.

<<fluorinated polyol>>
A specific example of the fluorine-based polyol is a linear or branched polyol obtained by a copolymerization reaction of a fluorine-containing monomer and a monomer having a hydroxyl group as essential components. Here, the fluorine-containing monomer is preferably a fluoroolefin such as tetrafluoroethylene, chlorotrifluoroethylene, trichlorofluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride, trifluoromethyltrifluoroethylene. etc. Examples of monomers having a hydroxyl group include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether and cyclohexanediol monovinyl ether; hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether; vinyl hydroxyalkyl crotonate; hydroxyl group-containing vinyl carboxylates, such as; monomers having hydroxyl groups, such as allyl esters; and the like.

<<monomer polyol>>
Specific examples of monomer polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5- Pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neo Pentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc. mentioned.

<<Reaction control agent (C)>>
The isocyanate group-terminated prepolymer (A) is not particularly limited as long as it can be prepared from diphenylmethane diisocyanate (A1) and a polyol (A2) having an ether unit or a polyol (A3) having an ester unit. Further, a reaction inhibitor (C) may be added as necessary.

The reaction inhibitor (C) is not particularly limited. Specific examples of the reaction inhibitor (C) include phosphite-based, acidic phosphate-based, polyoxyethylene alkyl ether phosphate-based, and the like. Examples of the phosphite ester include triphenyl phosphate, tridecyl phosphate, dibutyl hydrogen phosphate, and the like. Acidic phosphates include butyl acid phosphate, 2-ethylhexyl acid phosphate, isodecyl acid phosphate and the like. Polyoxyethylene alkyl ether phosphates include di(C12-15) pareth-2 phosphate, di(C12-15) pareth 4 phosphate, di(C12-15) pareth 6 phosphate, di(C12 -15) -Paleth 8 phosphate, di(C12-15)-Paleth 10 phosphate, phosphoric acid (mono, di) polyethylene glycol (3EO) C10-14 alcohol, polyoxyethylene tridecyl ether phosphate, phosphorus Acid (mono, di) polyethylene glycol (4EO) 4-nonylphenyl and the like.

<<NCO content>>
The NCO content of the isocyanate group-terminated urethane prepolymer (A) is preferably 5% by mass or more and 25% by mass or less. When the NCO content is 5% by mass or more and 25% by mass or less, it is possible to highly suppress the viscosity of the prepolymer from becoming excessively high, and the flowability during casting is improved, and during storage and use. Since the property stability becomes better, it becomes easier to obtain stable industrial machine parts, and the occurrence of molding defects can be suppressed.

<<Method for producing isocyanate group-terminated urethane prepolymer (A)>>
The method for producing the isocyanate group-terminated urethane prepolymer (A) is not particularly limited, but the following production method is preferred.
Diphenylmethane diisocyanate (A1) and reaction inhibitor (C) are put into a stirring vessel and stirred, and then a polyol (A2) having an ether unit or a polyol (A2) having an ester unit is added while maintaining the temperature in the vessel at 40 to 70 ° C. Add A3) and stir. Further, if necessary, an antioxidant and an antifoaming agent are added and stirred. Subsequently, while maintaining the temperature in the stirring vessel at 70 to 90° C., the urethanization reaction proceeds for about 2 to 5 hours, whereby an isocyanate group-terminated urethane prepolymer (A) can be obtained.

<Hydroxyl Terminal Curing Agent (B)>
The hydroxyl group-terminated curing agent (B) includes ethylene glycol (B1) and a triol (B2) having a number average molecular weight of 300 or more and 1000 or less having an ester unit or a triol (B3) having a number average molecular weight of 300 or more and 1000 or less having an ether unit. , consisting of

<<ethylene glycol (B1)>>
Ethylene glycol (B1) is preferably contained in an amount of 0.7 mmol/g or more and 1.3 mmol/g or less based on the total amount of the thermosetting polyurethane elastomer-forming composition. If it is less than 0.7 mmol, the amount of hard segments is so small that sufficient hardness and mechanical strength cannot be obtained even at room temperature. If it exceeds 1.3 mmol, the hard segment content is too large and the cohesive force is too strong, so that the resulting thermosetting polyurethane elastomer is brittle and causes poor appearance such as cracking, and sufficient mechanical strength cannot be obtained.

<<triol (B2) having an ester unit, triol (B3) having an ether unit>>
As the triol (B2) having a number average molecular weight of 300 or more and 1000 or less having an ester unit of the hydroxyl terminal curing agent (B), and the triol (B3) having a number average molecular weight of 300 or more and 1000 or less having an ether unit, the above-mentioned polyol having an ether unit (A2) and a polyol (A3) having an ester unit can be arbitrarily selected and used. Among them, it is preferable to use polypropylene triol or polycaprolactone triol having a number average molecular weight of 400 or more and 700 or less.

The triol (B2) having a number average molecular weight of 300 or more and 1000 or less having an ester unit or the triol (B3) having a number average molecular weight of 300 or more and 1000 or less having an ether unit is added to the total amount of the thermosetting polyurethane elastomer-forming composition. The content is preferably 0.01 mmol/g or more and 0.1 mmol/g or less.

If it is less than 0.01 mmol/g, the cross-linking density is low and molecular migration becomes easy, and the cohesive force of the hard segments becomes too strong. sufficient mechanical strength cannot be obtained. If it exceeds 0.1 mmol/g, the cross-linking density becomes too high and molecular migration is suppressed, so that the cohesive force of the hard segments decreases, resulting in a large decrease in mechanical strength at high temperatures.

In addition, when the number average molecular weight of the triols (B2) and (B3) is less than 300, the number of parts added becomes extremely small, making it difficult to introduce a sufficient amount of ether units or ester units, and sufficient effects of unit introduction are exhibited. become unable. When the number average molecular weight of the triols (B2) and (B3) exceeds 1000, the compatibility with ethylene glycol (B1) deteriorates and separation is observed, so storage stability as a hydroxyl terminal curing agent (B) is not obtained. Gender is difficult to assure.

In addition, the hydroxyl group-terminated curing agent (B) includes the aforementioned polyolefin polyols, acrylic polyols, silicone polyols, castor oil-based polyols, fluorine-based polyols, and monomer polyols, either alone or in combination, as long as the performance is not reduced. can do.

<<catalyst (D)>>
A catalyst (D) may be added to the hydroxyl group-terminated curing agent (B) as necessary. Although the catalyst (D) is not particularly limited, the urethanization catalyst for polyurethane (D1) is preferable from the viewpoint of improving mechanical properties and moldability.
If necessary, the polyurethane nurate catalyst (D2) and the polyurethane allophanat catalyst (D3) may be used together or alone. Potassium salts and quaternary ammonium salts are preferred as the polyurethane nurating catalyst (D2). N,N,N'-trimethylaminoethylethanolamine and N,N-dimethylaminoethoxyethanol are preferred as the allophanatizing catalyst (D3) for polyurethane.

<<<urethane catalyst for polyurethane (D1)>>>
The urethanization catalyst for polyurethane (D1) used in the urethanization reaction can be appropriately selected and used from conventionally known catalysts, such as amine catalysts, imidazole catalysts, diazacycloamine salt catalysts, metal-based catalysts, and the like.

Specific examples of amine catalysts include triethylenediamine, 2-methyltriethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylpropylenediamine, N,N , N′,N″,N″-pentamethyldiethylenetriamine, N,N,N′,N″,N″-pentamethyl-(3-aminopropyl)ethylenediamine, N,N,N′,N″,N″- Pentamethyldipropylenetriamine, N,N,N',N'-tetramethylhexamethylenediamine, bis(2-dimethylaminoethyl)ether, dimethylethanolamine, dimethylisopropanolamine, dimethylaminoethoxyethanol, N,N-dimethyl -N'-(2-hydroxyethyl)ethylenediamine, N,N-dimethyl-N'-(2-hydroxyethyl)propanediamine, bis(dimethylaminopropyl)amine, bis(dimethylaminopropyl)isopropanolamine and the like. .

Specific examples of imidazole catalysts include 1-methylimidazole, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole, 1-dimethylaminopropylimidazole, N,N-dimethylhexanolamine, N-methyl-N '-(2-hydroxyethyl)piperazine, 1-(2-hydroxyethyl)imidazole, 1-(2-hydroxypropyl)imidazole, 1-(2-hydroxyethyl)-2-methylimidazole, 1-(2-hydroxy propyl)-2-methylimidazole and the like.

Specific examples of diazacycloamine salt-based catalysts include 1,8-diazabicyclo(5,4,0)-undecene-7 or 1,5-diazahicyclo(4,3,0)-nonene-5 and octylic acid. , oleic acid, p-toluenesulfonic acid, formic acid, phenolic acid, orthophthalic acid, acetic acid, maleic acid, or boric acid.

Specific examples of metal-based catalysts include organic catalysts such as stannus diacetate, stannus dioctoate, stannus dioleate, stannus dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, and dioctyltin dilaurate. Examples include tin catalysts, nickel octylate, nickel naphthenate, cobalt octylate, cobalt naphthenate, bismuth octylate, bismuth naphthenate and the like.

In addition, these polyurethane urethanization catalysts (D1) can be used alone or in combination of two or more. The amount of the urethanization catalyst for polyurethane (D1) used is 0.001% by mass or more and 0.5% by mass with respect to the total mass of the isocyanate group-terminated urethane prepolymer (A) and the hydroxyl group-terminated curing agent (B). % or less, and more preferably 0.005% by mass or more and 0.10% by mass or less from the viewpoint of ease of reaction control.

<<<Polyurethane nurate catalyst (D2)>>>
The polyurethane nurating catalyst (D2) used in the nurating reaction can be appropriately selected from conventionally known catalysts and used. Examples thereof include ammonium carbonate, hydroxyalkylammonium hydroxide, organic weak acid salt, and alkali metal salt of carboxylic acid.

Specific examples of tertiary amines include triethylamine, N-ethylpiperidine, N,N'-dimethylpiperazine, N-ethylmorpholine, Mannich bases of phenolic compounds, and the like.

Specific examples of quaternary ammonium hydrogencarbonates include tetramethylammonium hydrogencarbonate, methyltriethylammonium hydrogencarbonate, ethyltrimethylammonium hydrogencarbonate, propyltrimethylammonium hydrogencarbonate, butyltrimethylammonium hydrogencarbonate, pentyltrimethyl ammonium hydrogen carbonate, hexyltrimethylammonium hydrogen carbonate, heptyltrimethylammonium hydrogen carbonate, octyltrimethylammonium hydrogen carbonate, nonyltrimethylammonium hydrogen carbonate, decyltrimethylammonium hydrogen carbonate, undecyltrimethylammonium hydrogen carbonate, dodecyltrimethyl ammonium hydrogen carbonate, tridecyltrimethylammonium hydrogen carbonate, tetradecyltrimethylammonium hydrogen carbonate, heptadecyltrimethylammonium hydrogen carbonate, hexadecyltrimethylammonium hydrogen carbonate, heptadecyltrimethylammonium hydrogen carbonate, octadecyltrimethylammonium hydrogen carbonate salt, (2-hydroxypropyl)trimethylammonium hydrogencarbonate, hydroxyethyltrimethylammonium hydrogencarbonate, 1-methyl-1-azania-4-azabicyclo[2.2.2]octanium hydrogencarbonate, 1,1-dimethyl -4-methylpiperidinium hydrogen carbonate and the like.

Quaternary ammonium carbonates include tetramethylammonium carbonate, methyltriethylammonium carbonate, ethyltrimethylammonium carbonate, propyltrimethylammonium carbonate, butyltrimethylammonium carbonate, pentyltrimethylammonium carbonate, hexyltrimethylammonium carbonate. , heptyltrimethylammonium carbonate, octyltrimethylammonium carbonate, nonyltrimethylammonium carbonate, decyltrimethylammonium carbonate, undecyltrimethylammonium carbonate, dodecyltrimethylammonium carbonate, tridecyltrimethylammonium carbonate, tetradecyltrimethylammonium carbonate salt, heptadecyltrimethylammonium carbonate, hexadecyltrimethylammonium carbonate, heptadecyltrimethylammonium carbonate, octadecyltrimethylammonium carbonate, (2-hydroxypropyl)trimethylammonium carbonate, hydroxyethyltrimethylammonium carbonate, 1-methyl -1-azania-4-azabicyclo[2,2,2]octanium carbonate, 1,1-dimethyl-4-methylpiperidinium carbonate and the like.

Hydroxyalkylammonium hydroxides include hydroxides such as trimethylhydroxypropylammonium, trimethylhydroxypropylammonium and triethylhydroxyethylammonium.

Alkali metal salts of carboxylic acids include alkali metal salts of carboxylic acids such as acetic acid, propionic acid, butyric acid, caproic acid, capric acid, valeric acid, octylic acid, myristic acid and naphthenic acid.

Moreover, these isocyanurate-forming catalysts for polyurethane (D2) can be used alone or in combination of two or more. The amount of the isocyanurate catalyst (D2) used is 0.001% by mass or more and 0.5% by mass with respect to the total mass of the isocyanate group-terminated urethane prepolymer (A) and the hydroxyl group-terminated curing agent (B). The following range is preferable, and from the viewpoint of ease of reaction control, the range of 0.005% by mass or more and 0.10% by mass or less is more preferable.

<<<Polyurethane allophanatization catalyst (D3)>>>
The allophanatization catalyst for polyurethane (D3) used in the allophanatization reaction can be appropriately selected from conventionally known catalysts, and for example, metal salts of carboxylic acids and alkanolamines can be used.

Specific examples of carboxylic acids include saturated aliphatic carboxylic acids such as acetic acid, propionic acid, butyric acid, caproic acid, octylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and 2-ethylhexanoic acid; cyclohexanecarboxylic acid, saturated monocyclic carboxylic acids such as cyclopentanecarboxylic acid; saturated multicyclic carboxylic acids such as bicyclo(4.4.0)decane-2-carboxylic acid; mixtures of the above-mentioned carboxylic acids such as naphthenic acid; oleic acid, linoleic acid , linolenic acid, soybean oil fatty acid, unsaturated aliphatic carboxylic acids such as tall oil fatty acids; aromatic aliphatic carboxylic acids such as diphenylacetic acid; benzoic acid, monocarboxylic acids such as aromatic carboxylic acids such as toluic acid; isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, curtaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexyldicarboxylic acid, Polycarboxylic acids such as α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α,β-diethylsuccinic acid, maleic acid, fumaric acid, trimellitic acid, pyromellitic acid, etc. mentioned.

Examples of metals constituting metal salts of carboxylic acids include alkali metals such as lithium, sodium and potassium; alkaline earth metals such as magnesium, calcium and barium; other typical metals such as tin and lead; manganese, iron, cobalt, transition metals such as nickel, copper, zinc and zirconium;
Specific examples of alkanolamine include N,N,N,N'-trimethylaminoethylethanolamine and N,N-dimethylaminoethoxyethanol.

The amount of allophanatization catalyst (D3) used is 0.001% by mass or more and 0.5% by mass or less with respect to the total mass of isocyanate group-terminated urethane prepolymer (A) and hydroxyl group-terminated curing agent (B). It is preferably used in the range of 0.005% by mass or more and 0.10% by mass or less from the viewpoint of ease of reaction control.

<Other ingredients>
In the thermosetting polyurethane elastomer-forming composition according to this embodiment, an antioxidant, an antifoaming agent, an ultraviolet absorber, or the like is further introduced as an additive into the thermosetting polyurethane elastomer-forming composition, if necessary. can be used

[Method for Producing Cured Product (Molded Product) of Thermosetting Polyurethane Elastomer-Forming Composition]
In this embodiment, using the thermosetting polyurethane elastomer-forming composition described above, a curing treatment (specifically, a treatment for accelerating curing by heating) is performed in a mold to urethanize, and A thermoset polyurethane elastomer molding with nurated, allophanatized linkages is produced.
In this case, the method for producing the thermosetting polyurethane elastomer molding according to one aspect of the present invention using the thermosetting polyurethane elastomer-forming composition according to one aspect of the present invention includes the following steps ( A method comprising 1) to (4) is preferred.

Step (1):
An isocyanate group-terminated prepolymer (A) and a hydroxyl group-terminated curing agent (B) are uniformly mixed to prepare a thermosetting polyurethane elastomer-forming composition. However, when the catalyst (D) is not included in the hydroxyl terminal curing agent (B) in advance, the catalyst (D) is added separately. If air bubbles are found due to entrainment of air, the bubbles are removed by vacuum defoaming or the like. This step preferably uses a dedicated polyurethane casting machine.

Step (2):
The thermosetting polyurethane elastomer-forming composition mixed in step (1) is immediately poured into the preheated mold (casting), and the polyurethane elastomer-forming composition is heat cured in the mold. A treatment is performed (specifically, a curing reaction is performed by heating). In this case, the temperature of the mold is preferably in the range of 90° C. or higher and 150° C. or lower from the viewpoint that the urethanization reaction can be easily and reliably carried out.

Step (3):
After the thermosetting polyurethane elastomer-forming composition is cured, the cured product (that is, the thermosetting polyurethane elastomer molded product) is removed from the mold (mold removal). The time required from casting to demolding is not particularly limited. A range of 1 to 12 hours is preferred due to the need for increased force. Further, even during the curing reaction, if the green strength is sufficiently high enough to be demolded, the mold may be demolded and heat curing may be continued for a predetermined time.

Step (4):
After curing, the thermosetting polyurethane elastomer molding (industrial machinery part) is demolded, and then preferably aged at room temperature for one week.

In addition, the compounding molar ratio (hereinafter abbreviated as "α value") obtained from the NCO group content of the NCO-terminated prepolymer and the OH group ( _NH2 group) content of the active hydrogen group-terminated curing agent at the time of casting, OH group (NH ₂ group)/NCO group is preferably in the range of 0.8 to 1.2, and more preferably in the range of 0.9 to 1.1. If it is 0.8 or more, it is suppressed that the crosslink density becomes too high due to nurate formation or allophanat formation due to excess isocyanate, so aggregation of hard segments tends to occur due to molecular migration, and mechanical strength at high temperatures is improved. Decrease is suppressed. Moreover, when it is 1.2 or less, the amount of the unreacted hydroxyl group-terminated curing agent is reduced, so that deterioration of physical properties, insufficient curing, and the like can be suppressed to a higher degree.

[Industrial machinery parts]
An industrial machine part according to one aspect of the present invention is a cured product obtained by curing the thermosetting polyurethane elastomer-forming composition described above at 90° C. or higher and 150° C. or lower, and has a JIS-A hardness of 80 or higher. 98 or less, and a storage modulus (E') at 100°C of 40 MPa or more.
Specific examples of industrial machinery parts include rolls, rollers, and conductive belts. In particular, suitable examples include industrial machine articles that are exposed to high temperatures during use, or that rise in temperature and require excellent mechanical strength and durability.

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these. In Examples and Comparative Examples, "%" means "% by mass".

Examples 1-6, Comparative Examples 1-10, Reference Examples 1-2
Various polyisocyanates (A1), reaction inhibitors (C), and antioxidants were charged and stirred in a 5 L stirring vessel filled with nitrogen according to the blending ratios shown in Tables 1, 2, and 3. After that, various polyols (A2, A3) were added and stirred according to the blending ratio while maintaining the temperature in the stirring vessel at 40 to 70°C. Subsequently, an antifoaming agent is added according to the compounding ratio, and the urethanization reaction is allowed to proceed for about 2 to 5 hours while maintaining the temperature in the stirring vessel at 70 to 90° C., thereby producing various isocyanate group-terminated urethane prepolymers (A). Obtained.

In addition, at the blending ratios shown in Tables 1, 2, and 3, various polyols (B1 to B4) and various catalysts (D) according to the blending ratio were put into a 5 L stirring vessel filled with nitrogen and stirred. Various hydroxyl group terminal curing agents (B) were obtained by mixing and stirring for about 1 to 3 hours while maintaining the internal temperature at 40 to 70°C.

Next, according to the formulations (blending ratios) shown in Tables 4, 5, and 6, an isocyanate group-terminated urethane prepolymer (A) preheated at 70 to 90° C. and a hydroxyl group-terminated prepolymer preheated at 40 to 120° C. By mixing the curing agent (B) or the amino group terminal curing agent (amine curing agent (B5)) with a two-liquid mixing urethane casting machine, the thermosetting polyurethane elastomer formability according to one aspect of the present invention A composition was prepared. Immediately, this composition was injected into a mold for forming a flat sheet with a thickness of 2 mm, which had been preheated to a curing temperature (120°C), and cured by heating for the specified time shown in Tables 4-6. It was removed from the mold (demolding). After that, it was cured in a constant temperature room at 25° C. for 1 week to obtain a polyurethane elastomer molding (sheet) according to one aspect of the present invention.

The abbreviations of raw materials used in Tables 1, 2 and 3 are as follows.
"Isocyanate"
(1) MDI; Millionate MT (manufactured by Tosoh Corporation), 4,4'-MDI, NCO content = 33.5%
(2) TDI: Coronate T-100 (manufactured by Tosoh Corporation), 2,4-TDI, NCO content = 48.2%

"Polyol"
(3) PTMG-3000; PTMG-3000 (manufactured by Mitsubishi Chemical Corporation), polytetramethylene glycol, hydroxyl value = 37.4 KOHmg/g
(4) PTMG-2000; PTMG-2000 (manufactured by Mitsubishi Chemical Corporation), polytetramethylene glycol, hydroxyl value = 56.1 KOHmg/g
(5) PTMG-1000; PTMG-1000 (manufactured by Mitsubishi Chemical Corporation), polytetramethylene glycol, hydroxyl value = 112.2 KOHmg/g
(6) PBA-2600; Nippon 135 (manufactured by Tosoh Corporation), polybutylene adipate, hydroxyl value = 43.2 KOHmg/g
(7) PEBA-1000; Nippon 141 (manufactured by Tosoh Corporation), polyethylene butylene adipate, hydroxyl value = 112.2 KOHmg/g
(8) PCL-300 (f = 3); Plaxel 303 (manufactured by Daicel), polycaprolactone triol, hydroxyl value = 561 KOHmg/g
(9) PCL-550 (f = 3); Plaxel 305 (manufactured by Daicel), polycaprolactone triol, hydroxyl value = 306 KOHmg/g
(10) PCL-850 (f = 3); Plaxel 308 (manufactured by Daicel), polycaprolactone triol, hydroxyl value = 198 KOHmg/g
(11) PCL-1250 (f = 3); Plaxel 312 (manufactured by Daicel), polycaprolactone triol, hydroxyl value = 134.7 KOHmg/g
(12) PPG-600 (f = 3); Sannics GP-600 (manufactured by Sanyo Chemical Industries, Ltd.), polyoxypropylene glyceryl ether, hydroxyl value = 281 KOHmg / g
(13) EG; ethylene glycol (manufactured by Mitsubishi Chemical Corporation), hydroxyl value = 1,808 KOHmg/g
(14) 1,4-BG; 1,4-butanediol (manufactured by Mitsubishi Chemical Corporation), hydroxyl value = 1,245 KOHmg/g
(15) 1,6-HG; 1,6-hexanediol (manufactured by Ube Industries, Ltd.), hydroxyl value = 950 KOHmg/g
(16) TMP; trimethylolpropane (Mitsubishi Gas Chemical Co., Ltd.), hydroxyl value = 1,247 KOHmg/g
(17) MOCA; 4,4'-diamino-3,3'-dichlorodiphenylmethane (manufactured by Ihara Chemical Industry Co., Ltd.), hydroxyl value (amino group) = 420 KOHmg/g

"catalyst"
(18) TOYOCAT B-41; manufactured by Tosoh Corporation, amine-based temperature-sensitive catalyst (19) TOYOCAT RX-5; manufactured by Tosoh Corporation, trimethylaminoethylethanolamine

"Others/Additives"
(20) PS-236; Phospholan PS-236 (reaction inhibitor, manufactured by Akzo Nobel), mono-di(C10-12) pareth-5 phosphate (21) I-1010; Irganox 1010 (antioxidant, BASF Japan) pentaerythritol tetrakis [3-(3',5'-di-t-butyl-4'-hydroxyphenyl) propionate]
(22) BYK-052; antifoaming agent manufactured by BYK-Chemie Japan

Tables 4, 5 and 6 show the characteristic values of the obtained molded sheets. Moreover, the characteristic evaluation method is as follows.

(1) JIS-A hardness: Measured using an A-type hardness tester according to JIS K7312.

(2) Tensile strength (TB), elongation (EB); measured according to JIS K7312.

(3) Tg, E′: Measurement was carried out under the following conditions using a thermal analyzer DMS6100 manufactured by Hitachi High-Tech Science Co., Ltd. (former name: Seiko Electronics Industry Co., Ltd.). The temperature showing the maximum value of tan δ (loss tangent) was defined as Tg (glass transition temperature). The E' (storage modulus) value at 100°C and 140°C was used as an index of heat resistance. For reference, a thermosetting polyurethane elastomer obtained from an isocyanate group-terminated urethane prepolymer made of TDI and an amino group-terminated curing agent, which is a conventional technique having excellent heat resistance, has an E' of about 60 MPa when it reaches 100°C, and 140°C. It shows about 60 MPa even when it reaches.
Sample shape: 20mm x 5mm x 2mm
Heating rate; -70°C to 250°C, 3°C/min
Measurement mode; Tensile Measurement frequency; 10Hz

(4) Molding Appearance (Visual Evaluation): The surfaces of the molded sheets obtained were visually observed and sorted according to the following three stages.
A: When the entire surface layer is uniform and smooth B: When 10% or more and less than 30% of surface layer peeling occurs C: When 30% or more and less than 60% of surface layer peeling occurs in the case of

According to Examples 1 to 8, the isocyanate group-terminated urethane prepolymer made of a unique MDI and a unique hydroxyl group-terminated curing agent, while using inexpensive and highly safe raw materials, have a high E' value at high temperatures. It was possible to suppress the decrease in mechanical strength and improve the heat resistance.

Comparative Examples 1 and 2 are examples in which a chain extender other than the essential component ethylene glycol (B1) was used. The resulting molded article had a low E' value at high temperatures and insufficient heat resistance, which was not sufficient for use in industrial machine parts requiring heat resistance.

Comparative Example 3 is an example in which the content of the triol (B2) having a number average molecular weight of 300 or more and 1000 or less exceeds 0.10 mmol/g with respect to the total amount of the thermosetting polyurethane elastomer-forming composition. By increasing the mixing ratio of the triol (B2) having a number average molecular weight of 300 or more and 1000 or less, the compatibility of the hydroxyl group-terminated curing agent (B) deteriorated, resulting in cloudiness. In addition, the resulting molded product had a slightly low hardness, a low E' value at high temperatures, and insufficient heat resistance, which was not sufficient for use in industrial machinery parts that require heat resistance. .

Comparative Example 4 is an example in which the content of the triol (B2) having a number average molecular weight of 300 or more and 1000 or less is less than 0.01 mmol/g with respect to the total amount of the thermosetting polyurethane elastomer-forming composition. The resulting molded article had cracks in some places and had a poor appearance, and the tensile strength and elongation at break were extremely low and not at a level sufficient for use in industrial machinery parts.

Comparative Example 5 is an example in which ethylene glycol (B1) and triols (B2, B3) having a number average molecular weight of 300 or more and 1000 or less and having an average molecular weight of less than 300 are used. The E' value at high temperatures was low and the heat resistance was insufficient, and the level was not sufficient for use in industrial machinery parts requiring heat resistance.

Comparative Example 6 is an example in which ethylene glycol (B1) and triols (B2, B3) having a number average molecular weight of 300 to 1000 and having an average molecular weight of 1000 or more are used. The hydroxyl group-terminated curing agent (B) caused turbidity and deteriorated compatibility due to the introduction of a triol having a large molecular weight. The obtained molded product had a rather poor appearance with fine cracks observed in some places, and its tensile strength and elongation at break were low and not at a level sufficient for use in industrial machinery parts.

Comparative Example 7 is an example in which the content of ethylene glycol (B1) is less than 0.70 mmol/g with respect to the total amount of the thermosetting polyurethane elastomer-forming composition. The resulting molded product had a slightly low hardness, a low E' value at high temperatures, and insufficient heat resistance, which was not sufficient for use in industrial machinery parts requiring heat resistance.

Comparative Example 8 is an example in which the content of ethylene glycol (B1) exceeds 1.30 mmol/g with respect to the total amount of the thermosetting polyurethane elastomer-forming composition. As the mixing ratio of ethylene glycol (B1) increased, the compatibility of the hydroxyl-terminated curing agent (B) deteriorated, resulting in cloudiness. In addition, the resulting molded product had a slightly low hardness, a low E' value at high temperatures, and insufficient heat resistance, which was not sufficient for use in industrial machinery parts that require heat resistance. .

Comparative Example 9 is an example of using an isocyanate group-terminated urethane prepolymer (A) having an ether unit and a hydroxyl group-terminated curing agent (B) having an ether unit. The resulting molded article had a low E' value at high temperatures and insufficient heat resistance, which was not sufficient for use in industrial machine parts requiring heat resistance.

Comparative Example 10 is an example in which an isocyanate group-terminated urethane prepolymer (A) having an ester unit and a hydroxyl group-terminated curing agent (B) having an ester unit are used. The resulting molded article had a low E' value at high temperatures and insufficient heat resistance, which was not sufficient for use in industrial machine parts requiring heat resistance.

Reference Examples 1 and 2 are existing examples in which an isocyanate group-terminated urethane prepolymer composed of tolylene diisocyanate and 4,4'-diamino-3,3'-dichlorodiphenylmethane are used as amino group-terminated curing agents. The E' value under high temperature is high and the heat resistance is high, but there is a carcinogenic risk.

According to Examples 1 to 6 , the isocyanate group-terminated urethane prepolymer made of a unique MDI and a unique hydroxyl group-terminated curing agent, while using inexpensive and highly safe raw materials, have a high E' value at high temperatures. It was possible to suppress the decrease in mechanical strength and improve the heat resistance.

Comparative Example 8 is an example in which the content of ethylene glycol (B1) exceeds 1.30 mmol/g with respect to the total amount of the thermosetting polyurethane elastomer-forming composition.

Claims (3)

A thermosetting polyurethane elastomer-forming composition comprising an isocyanate group-terminated urethane prepolymer (A) and a hydroxyl group-terminated curing agent (B),
The isocyanate group-terminated urethane prepolymer (A) contains at least
diphenylmethane diisocyanate (A1); and
and a polyol (A2) having an ether unit,
The hydroxyl group terminal curing agent (B) contains at least
ethylene glycol (B1);
and a triol (B2) having a number average molecular weight of 300 or more and 1000 or less having an ester unit,
The content of the ethylene glycol (B1) is 0.7 mmol/g or more and 1.3 mmol/g or less with respect to the total amount of the thermosetting polyurethane elastomer-forming composition,
A thermosetting polyurethane elastomer-forming composition, wherein the content of the triol (B2) is 0.01 mmol/g or more and 0.1 mmol/g or less relative to the total amount of the thermosetting polyurethane elastomer-forming composition. A thermosetting polyurethane elastomer-forming composition comprising an isocyanate group-terminated urethane prepolymer (A) and a hydroxyl group-terminated curing agent (B),
The isocyanate group-terminated urethane prepolymer (A) contains at least
diphenylmethane diisocyanate (A1); and
and a polyol (A3) having an ester unit,
The hydroxyl group terminal curing agent (B) contains at least
ethylene glycol (B1);
and a triol (B3) having an ether unit and a number average molecular weight of 300 or more and 1000 or less,
The content of the ethylene glycol (B1) is 0.7 mmol/g or more and 1.3 mmol/g or less with respect to the total amount of the thermosetting polyurethane elastomer-forming composition,
A thermosetting polyurethane elastomer-forming composition, wherein the content of the triol (B3) is 0.01 mmol/g or more and 0.1 mmol/g or less relative to the total amount of the thermosetting polyurethane elastomer-forming composition. A cured product obtained by curing the thermosetting polyurethane elastomer-forming composition according to claim 1 or 2 at 90° C. or higher and 150° C. or lower has a JIS-A hardness of 80 or higher and 98 or lower, and An industrial machine part having a storage modulus (E′) at 100° C. of 40 MPa or more.