JP2023070576A - polyurethane elastomer - Google Patents

Abstract

To provide a polyurethane elastomer excellent in bending resistance and compression set.SOLUTION: The polyurethane elastomer contains a reaction product of: a prepolymer component containing an isocyanate group-terminated prepolymer; and a curing agent. The isocyanate group-terminated prepolymer contains a reaction product of a polyisocyanate component and a polyol component containing a polyether polyol. The prepolymer component has an isocyanate group concentration of 6.0 mass% or less. The curing agent contains halogenated diethyltoluenediamine.SELECTED DRAWING: None

Description

The present invention relates to polyurethane elastomers.

Polyurethane elastomers have hard segments formed by reaction of polyisocyanate and low-molecular-weight polyol and soft segments formed by reaction of polyisocyanate and high-molecular-weight polyol. Polyurethane elastomers are rubber elastic bodies and are widely used in various industrial fields.

More specifically, polyurethane elastomers obtained by the following methods are known. That is, in this method, first, tolylene diisocyanate, polyoxytetramethylene glycol and polycaprolactone polyol are reacted to obtain an isocyanate group-terminated prepolymer. Next, the isocyanate group-terminated prepolymer is reacted with 3,3'-dichloro-4,4-diaminodiphenylmethane (MOCA) to obtain a polyurethane elastomer (see Patent Document 1, for example).

JP 2004-123767 A

On the other hand, depending on the application of the polyurethane elastomer, it may be required to improve durability. More specifically, improvements in flex resistance and compression set of polyurethane elastomers may be required.

The present invention is a polyurethane elastomer excellent in flex resistance and compression set.

The present invention [1] is a polyurethane elastomer containing a reaction product of a prepolymer component containing an isocyanate group-terminated prepolymer and a curing agent, wherein the isocyanate group-terminated prepolymer comprises a polyisocyanate component and a polyether polyol. wherein the prepolymer component has an isocyanate group concentration of 6.0% by mass or less, and the curing agent comprises a halogenated diethyltoluenediamine. .

The present invention [2] includes the polyurethane elastomer according to [1] above, wherein the polyether polyol includes polytetramethylene ether polyol.

In the polyurethane elastomer of the present invention, the isocyanate group-terminated prepolymer contained in the prepolymer component includes a reaction product of a polyisocyanate component and a polyol component including polyether polyol. Also, the isocyanate group concentration of the prepolymer component is 6.0% by mass or less. and the curing agent comprises halogenated diethyltoluenediamine. Such polyurethane elastomers are excellent in flex resistance and compression set.

Polyurethane elastomers are TPU (thermoplastic polyurethane resin) or TSU (thermosetting polyurethane resin). Preferably, the polyurethane elastomer is TSU (thermosetting polyurethane resin). Polyurethane elastomers comprise the reaction product of a prepolymer component and a curing agent (discussed below).

The prepolymer component contains an isocyanate group-terminated prepolymer as a main component. The proportion of the main component is 90% by mass or more, preferably 95% by mass or more, relative to the total amount of the prepolymer component. Moreover, the ratio of the main component is usually 100% by mass or less with respect to the total amount of the prepolymer components.

The isocyanate group-terminated prepolymer is a reaction product of a polyisocyanate component and a polyol component.

Polyisocyanate components include, for example, polyisocyanate monomers and polyisocyanate derivatives.

Polyisocyanate monomers include, for example, aromatic polyisocyanates, aliphatic polyisocyanates and araliphatic polyisocyanates. Aromatic polyisocyanates include, for example, diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), toluidine diisocyanate (TODI), paraphenylene diisocyanate, and naphthalene diisocyanate (NDI). Aliphatic polyisocyanates include, for example, chain aliphatic polyisocyanates and alicyclic polyisocyanates. Chain aliphatic polyisocyanates include, for example, ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI) and hexamethylene diisocyanate (HDI). Alicyclic polyisocyanates include, for example, isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), methylenebis(cyclohexylisocyanate) ( _H12MDI ), and bis(isocyanatomethyl)cyclohexane ( _H6XDI ). . Aroaliphatic polyisocyanates include, for example, xylylene diisocyanate (XDI) and tetramethylxylylene diisocyanate (TMXDI). Polyisocyanate monomers can be used alone or in combination of two or more.

Examples of polyisocyanate derivatives include modified products obtained by modifying polyisocyanate monomers by known methods. Modifications include, for example, uretdione modifications, isocyanurate modifications, allophanate modifications, polyol modifications, biuret modifications, urea modifications, oxadiazinetrione modifications and carbodiimide modifications. These can be used alone or in combination of two or more.

Polyisocyanate components can be used alone or in combination of two or more. The polyisocyanate component preferably includes a polyisocyanate monomer, more preferably a diisocyanate monomer. Further, the polyisocyanate monomer more preferably includes an aromatic polyisocyanate, more preferably includes diphenylmethane diisocyanate (MDI) and tolylene diisocyanate (TDI), and particularly preferably tolylene diisocyanate (TDI ). When tolylene diisocyanate (TDI) is used, particularly good flex resistance and compression set are obtained if the curing agent (described below) contains a halogenated diethyltoluenediamine.

Tolylene diisocyanates include, for example, 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate. These can be used alone or in combination of two or more. Preferable examples of tolylene diisocyanate include combined use of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate. As tolylene diisocyanate, 2,4-tolylene diisocyanate is also preferably used alone. Particularly good mechanical properties are obtained when these are used.

As tolylene diisocyanate, a combination of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate is particularly preferred. When 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate are used in combination, the content of 2,4-tolylene diisocyanate is, for example, 40% by mass or more, preferably , 60% by mass or more. Also, the content of 2,4-tolylene diisocyanate is, for example, 90% by mass or less. Also, the content of 2,6-tolylene diisocyanate is, for example, 10% by mass or more. Also, the content of 2,6-tolylene diisocyanate is, for example, 60% by mass or less, preferably 40% by mass or less.

The polyol component contains polyether polyol as an essential component. Polyether polyols are macropolyols. A macropolyol is an organic compound having two or more hydroxyl groups in its molecule and having a relatively high molecular weight. The number average molecular weight of the macropolyol is, for example, 400 or more and 20,000 or less. The number average molecular weight can be calculated by a known method from the hydroxyl equivalent and the average number of hydroxyl groups. Also, the number average molecular weight can be measured as a polystyrene-equivalent molecular weight by gel permeation chromatography (the same applies hereinafter).

Polyether polyols include, for example, polyoxyalkylene polyols. Polyoxyalkylene polyols include, for example, polyoxyalkylene (C2-3) polyols and polytetramethylene ether polyols.

Examples of polyoxyalkylene (C2-3) polyols include polyoxyethylene polyols, polyoxypropylene polyols, polyoxytriethylene polyols, and polyoxyethylene/polyoxypropylene polyols (random or block copolymers). be done.

Polytetramethylene ether polyols include, for example, ring-opening polymers (crystalline polytetramethylene ether glycol) obtained by cationic polymerization of tetrahydrofuran. Polytetramethylene ether polyols also include, for example, amorphous polytetramethylene ether glycol. In amorphous polytetramethylene ether glycol, tetrahydrofuran is copolymerized with alkyl-substituted tetrahydrofuran and/or dihydric alcohol. In addition, the crystallinity indicates the property of being solid at 25°C. Amorphous indicates the property of being liquid at 25°C.

Polyether polyols can be used alone or in combination of two or more. Polyether polyols preferably include polytetramethylene ether polyols.

The number average molecular weight of the polyether polyol is, for example, 400 or more, preferably 500 or more, more preferably 1000 or more. Further, the number average molecular weight of the polyether polyol is, for example, 15,000 or less, preferably 13,000 or less, more preferably 12,000 or less, still more preferably 10,000 or less, still more preferably 8,000 or less, and particularly preferably 5,000 or less. be.

The average number of hydroxyl groups of the polyether polyol is, for example, 2.0 or more. Also, the average number of hydroxyl groups of the polyether polyol is, for example, 6.0 or less, preferably 4.0 or less, more preferably 3.0 or less.

The polyol component can optionally contain polyols other than polyether polyols (hereinafter referred to as other polyols). Other polyols include other macropolyols and low molecular weight polyols.

Other macropolyols are macropolyols other than polyether polyols. Other macropolyols include, for example, polyester polyols, polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols and vinyl monomer modified polyols. Other macropolyols can be used alone or in combination of two or more.

Low-molecular-weight polyols are relatively low-molecular-weight organic compounds having two or more hydroxyl groups in the molecule. The molecular weight of the low-molecular-weight polyol is, for example, 40 or more and less than 400, preferably 300 or less. Low molecular weight polyols include, for example, dihydric alcohols, trihydric alcohols, and tetrahydric or higher alcohols. Examples of dihydric alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5- Pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol and dipropylene glycol are included. Trihydric alcohols include, for example, glycerin and trimethylolpropane. Tetrahydric or higher alcohols include, for example, pentaerythritol and diglycerin. Further, as the low-molecular-weight polyol, a polymer obtained by addition-polymerizing alkylene (C2-3) oxide to a dihydric to tetrahydric alcohol so as to have a number average molecular weight of less than 400 can be mentioned. These can be used alone or in combination of two or more.

Other polyols can be used alone or in combination of two or more. From the viewpoint of flex resistance and compression set, the content of other polyols is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less, relative to the total amount of polyol components. , more preferably 10% by mass or less, particularly preferably 0% by mass.

That is, the content of the polyether polyol is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more, relative to the total amount of the polyol component. , particularly preferably 100% by mass. In other words, the polyol component preferably consists of polyether polyols.

An isocyanate group-terminated prepolymer is obtained, for example, by reacting a polyisocyanate component and a polyol component in a predetermined ratio (prepolymer step).

The blending ratio of the polyisocyanate component and the polyol component is adjusted so that the isocyanate groups are excessive relative to the hydroxyl groups. More specifically, the equivalent ratio of isocyanate groups in the polyisocyanate component to hydroxyl groups in the polyol component (isocyanate groups/hydroxyl groups) is, for example, 1.5 or more, preferably 1.8 or more, more preferably 2 or more, more preferably 2.5 or more. In addition, the equivalent ratio of isocyanate groups in the polyisocyanate component to hydroxyl groups in the polyol component (isocyanate groups/hydroxyl groups) is, for example, 10 or less, preferably 7 or less, more preferably 5 or less, and still more preferably 4. .5 or less.

Polymerization methods include, for example, bulk polymerization and solution polymerization. In bulk polymerization, for example, the polyisocyanate component and the polyol component are reacted under a stream of nitrogen. The reaction temperature is, for example, 50° C. or higher. Also, the reaction temperature is, for example, 250° C. or lower, preferably 200° C. or lower. Also, the reaction time is, for example, 0.5 hours or longer, preferably 1 hour or longer. Also, the reaction time is, for example, 15 hours or less. In solution polymerization, a polyisocyanate component and a polyol component are reacted in the presence of a known organic solvent. The reaction temperature is, for example, 50° C. or higher. Also, the reaction temperature is, for example, 120° C. or lower, preferably 100° C. or lower. Also, the reaction time is, for example, 0.5 hours or longer, preferably 1 hour or longer. Also, the reaction time is, for example, 15 hours or less.

Moreover, a known urethanization catalyst can be added as necessary. Urethane-forming catalysts include, for example, amines and organometallic compounds. The addition ratio of the urethanization catalyst is appropriately set according to the purpose and application.

Thereby, a reaction mixture containing an isocyanate group-terminated prepolymer is obtained. Moreover, the reaction mixture obtained by the above reaction can contain unreacted polyisocyanate (isocyanate monomer) in addition to the isocyanate group-terminated prepolymer. Unreacted polyisocyanate is removed from the reaction mixture by known removal methods, if desired. Removal methods include, for example, distillation and extraction.

The prepolymer component may be a component containing an isocyanate group-terminated prepolymer and unreacted polyisocyanate. The prepolymer component may also be a component containing an isocyanate group-terminated prepolymer and containing no unreacted polyisocyanate. The prepolymer component is preferably a component containing an isocyanate group-terminated prepolymer and containing no unreacted polyisocyanate. That is, the prepolymer component preferably consists of an isocyanate group-terminated prepolymer.

Such a prepolymer component can be obtained, for example, by reacting a polyisocyanate component and a polyol component in an equivalent ratio and reaction conditions that do not produce unreacted polyisocyanate. Such a prepolymer component can also be obtained by removing unreacted polyisocyanate from the above reaction mixture.

The isocyanate group concentration of the prepolymer component is, for example, 1% by mass or more, preferably 1.5% by mass or more, and more preferably 2.0% by mass or more. Further, the isocyanate group concentration of the prepolymer component is 6.0% by mass or less, preferably 5.0% by mass or less, more preferably 4.2% by mass or less, further preferably 4.0% by mass or less, Especially preferably, it is 3.0% by mass or less. The isocyanate group concentration (isocyanate group content) can be determined by a known method such as titration with di-n-butylamine or FT-IR analysis.

When the isocyanate group concentration of the prepolymer component is below the above upper limit, especially excellent flex resistance and compression set can be obtained if the curing agent (described later) contains halogenated diethyltoluenediamine. Moreover, when the isocyanate group concentration of the prepolymer component is within the above range, an excellent pot life can be obtained.

Then, the polyurethane elastomer is obtained by reacting the prepolymer component and the curing agent (chain elongation step).

The curing agent contains halogenated diethyltoluenediamine as an essential component. The use of halogenated diethyltoluenediamine provides polyurethane elastomers with excellent flex resistance and compression set.

Halogenated diethyltoluenediamine is a halide of diethyltoluenediamine. Diethyltoluenediamine includes 2,4-diethyltoluenediamine and 2,6-diethyltoluenediamine. These can be used alone or in combination of two or more.

That is, halogenated diethyltoluenediamine is a compound in which a hydrogen atom directly bonded to a benzene ring of diethyltoluenediamine is substituted with a halogen atom. The halogenated diethyltoluenediamine includes a compound in which the 6-position hydrogen of 2,4-diethyltoluenediamine is substituted with a halogen atom. Halogenated diethyltoluenediamine includes a compound in which the 4-position hydrogen of 2,6-diethyltoluenediamine is substituted with a halogen atom.

Halogen atoms include, for example, fluorine, chlorine, bromine and iodine. A halogen atom can be used alone or in combination of two or more. Halogen atoms preferably include chlorine and bromine, more preferably chlorine.

Halogenated diethyltoluenediamines include, for example, 4-chloro-3,5-diethyltoluene-2,6-diamine, 6-chloro-3,5-diethyltoluene-2,4-diamine, 4-bromo-3, 5-diethyltoluene-2,6-diamine and 6-bromo-3,5-diethyltoluene-2,4-diamine. These can be used alone or in combination of two or more. Preferred halogenated diethyltoluenediamines include 4-chloro-3,5-diethyltoluene-2,6-diamine and 6-chloro-3,5-diethyltoluene-2,4-diamine, and more A combination of 4-chloro-3,5-diethyltoluene-2,6-diamine and 6-chloro-3,5-diethyltoluene-2,4-diamine is preferred.

The curing agent can optionally contain other polyamines. Other polyamines are polyamine compounds other than halogenated diethyltoluenediamine.

Other polyamines include, for example, aromatic polyamines, araliphatic polyamines, aliphatic polyamines and cycloaliphatic polyamines.

Aromatic polyamines include, for example, aromatic diamines. Examples of aromatic diamines include 2,4-diethyltoluenediamine, 2,6-diethyltoluenediamine, dimethylthiotoluenediamine, 4,4'-diphenylmethanediamine, and 3,3'-dichloro-4,4'-diphenylmethane. Diamine (MOCA), 4,4'-methylenebis(n-sec-butylaniline), 4,4'-methylenebis(2,6-diethylaniline), 4,4'-diamino-3,3'-diethyl-5 ,5′-dimethyldiphenylmethane and tetrachloro-4,4′-diaminodiphenylmethane. Moreover, a commercial item is also mentioned as an aromatic polyamine. Commercially available products include, for example, Etacure 100 (mixture of 2,4-diethyltoluenediamine and 2,6-diethyltoluenediamine, manufactured by Albemarle), Etacure 300 (dimethylthiotoluenediamine, manufactured by Albemarle), Etacure 420 (4 , 4′-methylenebis(n-sec-butylaniline), manufactured by Albemarle), Lonza Cure M-DEA (4,4′-methylenebis(2,6-diethylaniline), manufactured by Lonza), Cure Hard MED-J ( 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane) and TCDAM (tetrachloro-4,4'-diaminodiphenylmethane, manufactured by Ihara Chemical Co., Ltd.).

Araliphatic polyamines include, for example, araliphatic diamines. Araliphatic diamines include, for example, 1,3-xylylenediamine and 1,4-xylylenediamine.

Alicyclic polyamines include, for example, alicyclic diamines. Alicyclic diamines include, for example, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, bis-(4-aminocyclohexyl)methane, diaminocyclohexane, 3,9-bis(3-aminopropyl )-2,4,8,10-tetraoxaspiro[5,5]undecane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-bis(aminoethyl ) cyclohexane and 1,4-bis(aminoethyl)cyclohexane.

Aliphatic polyamines include, for example, aliphatic diamines. Aliphatic diamines include, for example, ethylenediamine, propylenediamine, pentamethylenediamine, hexamethylenediamine, hydrazine, 1,2-diaminoethane, 1,2-diaminopropane and 1,3-diaminopentane.

Other polyamines can be used alone or in combination of two or more. The content of other polyamines is appropriately adjusted within a range that does not impair the excellent effects of the present invention. From the viewpoint of pot life, the content of other polyamines is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 10% by mass or less, relative to the total amount of the curing agent. It is 0% by mass. That is, the curing agent preferably does not contain other polyamines.

The curing agent can optionally contain a low molecular weight polyol. Low-molecular-weight polyols include the low-molecular-weight polyols described above as polyol components. These can be used alone or in combination of two or more. From the viewpoint of flex resistance and compression set, the content of the low-molecular-weight polyol is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 20% by mass, relative to the total amount of the curing agent. Below, more preferably 10% by mass or less, particularly preferably 0% by mass. That is, the curing agent preferably does not contain low molecular weight polyols.

That is, the content of the diethyltoluenediamine halide is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass, relative to the total amount of the curing agent. % or more, particularly preferably 100% by mass. In other words, the curing agent preferably consists of halogenated diethyltoluenediamine.

The mixing ratio of the prepolymer component and the curing agent is adjusted as the equivalent ratio of the active hydrogen groups of the curing agent to the isocyanate groups of the prepolymer component. The active hydrogen group is a hydroxyl group and/or an amino group, preferably an amino group.

More specifically, for example, the equivalent ratio (active hydrogen group/isocyanate group) of the active hydrogen group (amino group) of the curing agent to the isocyanate group in the prepolymer component is, for example, 0.75 or more, preferably 0. 0.9 or more, for example, 1.3 or less, preferably 1.2 or less.

Also, the reaction between the prepolymer component and the curing agent employs, for example, bulk polymerization and/or solution polymerization. The reaction temperature is, for example, room temperature or higher, preferably 50° C. or higher. Moreover, the reaction temperature is, for example, 200° C. or lower, preferably 150° C. or lower. Also, the reaction time is, for example, 5 minutes or longer, preferably 1 hour or longer. Also, the reaction time is, for example, 72 hours or less, preferably 48 hours or less. When mixing the prepolymer component and the curing agent, if necessary, a urethanization catalyst can be added in an appropriate proportion.

This results in a polyurethane elastomer comprising the reaction product of the prepolymer component and the curing agent.

Also preferably, the mixture of prepolymer component and curing agent is optionally degassed, cured in a preheated mold and demolded. Thereby, a polyurethane elastomer molded into a desired shape is obtained.

Polyurethane elastomers can also be heat treated. The heat treatment temperature is, for example, 50° C. or higher, preferably 80° C. or higher. Also, the heat treatment temperature is, for example, 200° C. or lower, preferably 150° C. or lower. Also, the heat treatment time is, for example, 30 minutes or longer, preferably 1 hour or longer. Also, the heat treatment time is, for example, 30 hours or less, preferably 20 hours or less.

Also, the polyurethane elastomer can be cured. The curing temperature is, for example, 10°C or higher, preferably 20°C or higher. Also, the curing temperature is, for example, 50° C. or lower, preferably 40° C. or lower. Also, the curing time is, for example, 1 hour or longer, preferably 10 hours or longer. Also, the curing time is, for example, 20 days or less, preferably 10 days or less.

The polyurethane elastomer may optionally contain known additives in addition to the reaction product of the prepolymer component and the curing agent. That is, the polyurethane elastomer may be a polyurethane elastomer composition.

Additives include, for example, antioxidants, heat stabilizers, ultraviolet absorbers, light stabilizers, antiblocking agents, release agents, pigments, dyes, lubricants, fillers, hydrolysis inhibitors, rust inhibitors, and bluing. agents. The amount and timing of addition of the additive are appropriately set according to the purpose and application.

In the above polyurethane elastomer, the isocyanate group-terminated prepolymer contained in the prepolymer component contains a reaction product of a polyisocyanate component and a polyol component containing polyether polyol. Also, the isocyanate group concentration of the prepolymer component is 6.0% by mass or less. and the curing agent comprises halogenated diethyltoluenediamine. Such polyurethane elastomers are excellent in flex resistance and compression set. Furthermore, the above polyurethane elastomers also have excellent mechanical properties.

Therefore, polyurethane elastomers can be molded into arbitrary shapes. And the molded article is suitably used in various industrial fields. A method for molding the polyurethane elastomer is not particularly limited. Examples of molding methods include heat compression molding, injection molding, extrusion molding, and melt spinning molding. Shapes after molding include, for example, pellets, plates, fibers, strands, films, sheets, pipes, bottles, hollows, boxes, and buttons.

Applications of molded articles are not particularly limited, but examples include transparent hard plastics, coating materials, adhesives, adhesives, waterproof materials, potting agents, inks, binders, films, sheets, bands, belts, tubes, blades, Speakers, sensors, outsoles, threads, fibers, non-woven fabrics, cosmetics, shoes, heat insulating materials, sealing materials, tape materials, sealing materials, photovoltaic power generation components, robot components, android components, wearable components, clothing products, sanitary products , cosmetics, furniture, food packaging materials, sporting goods, leisure goods, medical supplies, nursing care products, housing materials, acoustic materials, lighting materials, anti-vibration materials, sound insulation materials, daily necessities, miscellaneous goods, cushions, bedding, stress absorption materials, stress relaxation materials, automotive interior materials, automotive exterior materials, railway materials, aircraft materials, optical materials, OA equipment materials, sundry surface protection materials, semiconductor sealing materials, self-healing materials, health equipment, eyeglass lenses, toys, Packings, cable sheaths, wire harnesses, telecommunication cables, automotive wiring, computer wiring, industrial goods, shock absorbers and semiconductor goods.

Next, the present invention will be described based on Examples and Comparative Examples, but the present invention is not limited by these. "Parts" and "%" are based on mass unless otherwise specified. In addition, specific numerical values such as the mixing ratio (content ratio), physical property values, and parameters used in the following description are the corresponding mixing ratios ( content ratio), physical properties, parameters, etc. be able to.

Preparation Example 1 (Preparation of prepolymers 1 to 7)
Prepolymers 1 to 7 (commercially available) shown below were prepared.
Prepolymer 1: Hyprene (registered trademark) L-80 (TDI/polyoxytetramethylene ether glycol-based prepolymer, NCO = 2.9%, manufactured by Mitsui Chemicals)
Prepolymer 2: Hyprene (registered trademark) L-100 (TDI/polyoxytetramethylene ether glycol-based prepolymer, NCO = 4.3%, manufactured by Mitsui Chemicals)
Prepolymer 3: Takenate (registered trademark) L-2760 (TDI/polyoxytetramethylene ether glycol-based prepolymer, NCO = 6.4%, manufactured by Mitsui Chemicals)
Prepolymer 4: Takenate (registered trademark) L-1170 (TDI/polyoxypropylene glycol-based prepolymer, NCO = 2.5%, manufactured by Mitsui Chemicals)
Prepolymer 5: Hyprene (registered trademark) U-62 (TDI/polyoxypropylene glycol-based prepolymer, NCO = 4.5%, manufactured by Mitsui Chemicals)
Prepolymer 6: Cyanaprene (registered trademark) A-8QM (TDI/polyester polyol-based prepolymer, NCO = 3.1%, manufactured by Mitsui Chemicals)
Prepolymer 7: Cyanaprene (registered trademark) D-5QM (TDI/polyester polyol-based prepolymer, NCO = 5.0%, manufactured by Mitsui Chemicals)

Examples 1-4 and Comparative Examples 1-12
The prepolymers listed in Tables 1-4 were heated to 80°C. Also, the curing agents listed in Tables 1 to 4 were heated to 120°C. Then, the prepolymer component and the curing agent were mixed at a ratio such that the equivalent ratio (active hydrogen group/NCO) was 0.95. Then, these mixtures were poured into a mold preheated to 110° C. and cured in an oven at 110° C. for 2 hours to obtain a polyurethane elastomer. Also, the polyurethane elastomer was demolded from the mold. The polyurethane elastomer was then heat treated in an oven at 110° C. for 16 hours. Thus, a sheet-shaped polyurethane elastomer was obtained.

As molds, a sheet-shaped mold with a thickness of 2 mm and a button-shaped mold with a diameter of 29 mm and a thickness of 12 mm were used.
<Evaluation>
(1) Pot life The time from the start of mixing the prepolymer component and the curing agent to the loss of fluidity was measured.

(2) Flexibility A sheet-shaped polyurethane elastomer having a thickness of 2 mm was used. Polyurethane elastomer test pieces were prepared according to JIS K 6260 (2010). In addition, a hole with a diameter of 2.5 mm was made in the test piece. After that, the test piece was bent 150,000 times at a speed of 300 times/minute using a De Mattia bending tester (manufactured by Ueshima Seisakusho, model: FT-1503). Then, the number of bending times until cracks occurred in the test piece was measured.

(3) Hardness A button-shaped polyurethane elastomer having a diameter of 29 mm and a thickness of 12 mm was used. Shore A hardness of the polyurethane elastomer was measured according to JIS K 7312 (1996).

(4) Impact resilience A button-shaped polyurethane elastomer having a diameter of 29 mm and a thickness of 12 mm was used. The impact resilience of the polyurethane elastomer was measured according to JIS K 7311 (1995).

(5) Tensile strength A sheet-shaped polyurethane elastomer having a thickness of 2 mm was used. The tensile strength of the polyurethane elastomer was measured according to JIS K 7312 (1996). A No. 3 dumbbell-shaped test piece was used. Moreover, the tensile speed was set to 500 mm/min.

(6) Elongation A sheet-shaped polyurethane elastomer having a thickness of 2 mm was used. The elongation at break of the polyurethane elastomer was measured according to JIS K 7312 (1996). A No. 3 dumbbell-shaped test piece was used. Moreover, the tensile speed was set to 500 mm/min.

(7) Tear Strength A sheet-shaped polyurethane elastomer having a thickness of 2 mm was used. The tear strength of the polyurethane elastomer was measured according to JIS K 7312 (1996). An angle-shaped test piece was used. Moreover, the tear speed was set to 500 mm/min.

(8) Compression set A button-shaped polyurethane elastomer having a diameter of 29 mm and a thickness of 12 mm was used. The compression set of the polyurethane elastomer was measured according to JIS K 6262 (2013). The measurement temperature was 70° C., the compression ratio was 25%, and the compression time was 24 hours.

The details of the abbreviations in the table are described below.
MOCA: 3,3′-dichloro-4,4′-diphenylmethanediamine Ethacure 100: A mixture of 2,4-diethyltoluenediamine and 2,6-diethyltoluenediamine, Albemarle Ethacure 300: 3,5-bis( A mixture of methylthio)-2,6-toluenediamine and 3,5-bis(methylthio)-2,4-toluenediamine, Albemarle P-25: Ronzacure P-25, 4-chloro-3,5-diethyl Mixture of toluene-2,6-diamine and 6-chloro-3,5-diethyltoluene-2,4-diamine, prepolymer manufactured by Lonza: prepolymer component obtained in Preparation Example NCO concentration: prepolymer component The isocyanate group concentration of 6.0% by mass
PTMEG: polytetramethylene ether glycol PPG: polyoxypropylene glycol PES: polyester polyol

<Discussion>
In Example 1 and Comparative Examples 10 to 12, the polyol component contains polyether polyol, and the isocyanate group concentration of the prepolymer component is 6.0% by mass or less. In such cases, the polyurethane elastomer of Example 1 (curing agent P-25) exhibits superior flex resistance and compression resistance compared to the polyurethane elastomers of Comparative Examples 10-12 (curing agent MOCA, Etacure 100 and Etacure 300). It has permanent set.

Also in Example 2 and Comparative Examples 13 to 15, the polyol component contains polyether polyol, and the isocyanate group concentration of the prepolymer component is 6.0% by mass or less. In such cases, the polyurethane elastomer of Example 2 (curing agent P-25) exhibits superior flex resistance and compression resistance compared to the polyurethane elastomers of Comparative Examples 13-15 (curing agent MOCA, Etacure 100 and Etacure 300). It has permanent set.

That is, under the above conditions, if the curing agent contains the halogenated diethyltoluenediamine, superior flex resistance and compression set are obtained compared to the case where the curing agent does not contain the halogenated diethyltoluenediamine. be done.

On the other hand, in Comparative Examples 1 to 4, the polyol component did not contain polyether polyol. In such a case, the flex resistance of the polyurethane elastomer of Comparative Example 1 (curing agent P-25) was the same as that of the polyurethane elastomers of Comparative Examples 2 to 4 (curing agent MOCA, Etacure 100 and Etacure 300). degree.

Furthermore, in Comparative Examples 6 to 9, the isocyanate group concentration of the prepolymer component exceeded 6.0% by mass. In such a case, the compression set of the polyurethane elastomer of Comparative Example 6 (curing agent P-25) was the same as that of the polyurethane elastomers of Comparative Examples 7 to 9 (curing agent MOCA, Etacure 100 and Etacure 300). degree.

Claims (2)

A polyurethane elastomer comprising a reaction product of a prepolymer component comprising an isocyanate group-terminated prepolymer and a curing agent,
The isocyanate group-terminated prepolymer contains a reaction product of a polyisocyanate component and a polyol component containing a polyether polyol,
The isocyanate group concentration of the prepolymer component is 6.0% by mass or less,
A polyurethane elastomer, wherein the curing agent comprises a halogenated diethyltoluenediamine. 2. The polyurethane elastomer of claim 1, wherein said polyether polyol comprises polytetramethylene ether polyol.