Polyurethane resin, elastic molded product, method for producing polyurethane resin, and prepolymer composition

Abstract

To provide a polyurethane resin which has excellent mechanical strength and can suppress formation of air bubbles, and to provide an elastic molding, a method for producing the polyurethane resin, and a prepolymer composition which enables production of the polyurethane resin.SOLUTION: A polyurethane resin contains a reaction product of a prepolymer composition and a chain extender, wherein the prepolymer composition contains an isocyanate group terminal prepolymer and an isocyanate monomer, the isocyanate group terminal prepolymer contains a reaction product of a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane, and a polyol component containing macropolyol, the isocyanate monomer contains bis(isocyanatomethyl)cyclohexane, a weight average molecular weight of the isocyanate group terminal prepolymer is 7,000 or more and 14,000 or less, and isocyanate group concentration of the prepolymer composition is 15.0 mass% or more and 20.0 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyurethane resin, an elastic molded article, a method for producing a polyurethane resin, and a prepolymer composition. [Background technology]

[0002] The polyurethane resin has, for example, a soft segment formed by the reaction of a polyisocyanate and a macropolyol, and a hard segment formed by the reaction of a polyisocyanate and a chain extender.

[0003] More specifically, a polyurethane resin obtained by the following method is known: First, 1,4-bis(isocyanatomethyl)cyclohexane is reacted with a polyester polyol to obtain an isocyanate-terminated prepolymer having an isocyanate group content of 17.74 mass%, and then the isocyanate-terminated prepolymer is reacted with 1,4-butanediol to obtain a polyurethane resin (see, for example, Patent Document 1 (Synthesis Example 24, Example 20)). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 069802 Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the application, polyurethane resins are required to have both excellent mechanical strength and the ability to suppress entrapment of air bubbles. However, the polyurethane resin of Patent Document 1 may not be able to sufficiently suppress entrapment of air bubbles.

[0006] The present invention relates to a polyurethane resin that has excellent mechanical strength and is capable of suppressing entrapment of air bubbles, an elastic molded article, a method for producing such a polyurethane resin, and a prepolymer composition from which such a polyurethane resin can be obtained. [Means for solving the problem]

[0007] The present invention [1] comprises a polyurethane resin comprising a reaction product of a prepolymer composition and a chain extender, wherein the prepolymer composition comprises an isocyanate group-terminated prepolymer and an isocyanate monomer, the isocyanate group-terminated prepolymer comprises a reaction product of a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane and a polyol component containing a macropolyol, the isocyanate monomer comprises bis(isocyanatomethyl)cyclohexane, the weight average molecular weight of the isocyanate group-terminated prepolymer is 7000 or more and 14000 or less, and the isocyanate group concentration of the prepolymer composition is 15.0 mass% or more and 20.0 mass% or less.

[0008] The present invention [2] includes an elastic molded article containing the polyurethane resin described in [1] above.

[0009] The present invention [3] includes a method for producing a polyurethane resin, comprising: a first step of synthesizing an isocyanate-terminated prepolymer by reacting a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane with a polyol component containing a macropolyol at an equivalent ratio (NCO / OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component exceeding 1.0; a second step of mixing the isocyanate-terminated prepolymer with an isocyanate monomer containing bis(isocyanatomethyl)cyclohexane to prepare a prepolymer composition containing the isocyanate-terminated prepolymer and the isocyanate monomer; and a third step of reacting the prepolymer composition with a chain extender to synthesize a polyurethane resin.

[0010] The present invention [4] includes a prepolymer composition comprising an isocyanate group-terminated prepolymer and an isocyanate monomer, wherein the isocyanate group-terminated prepolymer comprises a reaction product of a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane and a polyol component containing a macropolyol, wherein the weight-average molecular weight of the isocyanate group-terminated prepolymer is 7,000 or more and 14,000 or less, the isocyanate monomer contains bis(isocyanatomethyl)cyclohexane, and the isocyanate group concentration is 15.0 mass% or more and 20.0 mass% or less. [Effects of the Invention]

[0011] In the polyurethane resin and elastic molded article of the present invention, the prepolymer composition includes an isocyanate-terminated prepolymer and an isocyanate monomer. The isocyanate-terminated prepolymer includes a reaction product of a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane and a polyol component containing a macropolyol. The isocyanate monomer includes bis(isocyanatomethyl)cyclohexane. The isocyanate-terminated prepolymer has a weight-average molecular weight within a predetermined range. The prepolymer composition also has an isocyanate group concentration within a predetermined range. That is, the prepolymer composition contains an isocyanate-terminated prepolymer with a relatively high weight-average molecular weight and bis(isocyanatomethyl)cyclohexane, and the prepolymer composition has a relatively high isocyanate group concentration.

[0012] Therefore, the polyurethane resin and elastic molded article of the present invention have excellent mechanical strength and can suppress entrapment of air bubbles.

[0013] In the method for producing a polyurethane resin of the present invention, a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane is first reacted with a polyol component containing a macropolyol at an equivalent ratio (NCO / OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component of greater than 1.0 to synthesize an isocyanate-terminated prepolymer. In other words, this process produces an isocyanate-terminated prepolymer with a relatively high weight-average molecular weight.

[0014] In the method for producing a polyurethane resin of the present invention, the isocyanate-terminated prepolymer is then mixed with an isocyanate monomer containing bis(isocyanatomethyl)cyclohexane to prepare a prepolymer composition containing the isocyanate-terminated prepolymer and the isocyanate monomer. In other words, in this step, a prepolymer composition having a relatively high isocyanate group concentration is obtained.

[0015] In the method for producing a polyurethane resin of the present invention, the prepolymer composition is then reacted with a chain extender to obtain a polyurethane resin.

[0016] According to such a method, a polyurethane resin having excellent mechanical strength can be obtained, and the inclusion of air bubbles in the polyurethane resin can be suppressed.

[0017] The prepolymer composition of the present invention includes an isocyanate-terminated prepolymer and an isocyanate monomer. The isocyanate-terminated prepolymer includes a reaction product of a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane and a polyol component containing a macropolyol. The isocyanate monomer includes bis(isocyanatomethyl)cyclohexane. The weight-average molecular weight of the isocyanate-terminated prepolymer is within a predetermined range, and the isocyanate group concentration of the prepolymer composition is within a predetermined range.

[0018] Therefore, according to the prepolymer composition of the present invention, a polyurethane resin having excellent mechanical strength can be obtained, and the entrapment of air bubbles in the polyurethane resin can be suppressed. DETAILED DESCRIPTION OF THE INVENTION

[0019] The polyurethane resin of the present invention includes a reaction product of a prepolymer composition and a curing agent (described later). Preferably, the polyurethane resin is a reaction product of the prepolymer composition and a curing agent (described later). That is, the polyurethane resin is preferably a cured urethane product obtained by reacting and curing the prepolymer composition with the curing agent (described later).

[0020] The prepolymer composition includes an isocyanate-terminated prepolymer and an isocyanate monomer. Preferably, the prepolymer composition consists of an isocyanate-terminated prepolymer and an isocyanate monomer.

[0021] The isocyanate-terminated prepolymer comprises a reaction product of a polyisocyanate component and a polyol component. Preferably, the isocyanate-terminated prepolymer comprises a reaction product of a polyisocyanate component and a polyol component.

[0022] The polyisocyanate component contains bis(isocyanatomethyl)cyclohexane as an essential component. Examples of bis(isocyanatomethyl)cyclohexane include 1,3-bis(isocyanatomethyl)cyclohexane and 1,4-bis(isocyanatomethyl)cyclohexane. From the viewpoint of improving the mechanical strength of the polyurethane resin, 1,4-bis(isocyanatomethyl)cyclohexane, which has a symmetrical structure, is preferably used.

[0023] 1,4-bis(isocyanatomethyl)cyclohexane has two stereoisomers: cis-1,4-bis(isocyanatomethyl)cyclohexane and trans-1,4-bis(isocyanatomethyl)cyclohexane. Hereinafter, cis-1,4-bis(isocyanatomethyl)cyclohexane may be referred to as the cis 1,4 isomer. Trans-1,4-bis(isocyanatomethyl)cyclohexane may be referred to as the trans 1,4 isomer. The total amount of the trans 1,4 isomer and the cis 1,4 isomer is 100 mol%.

[0024] In 1,4-bis(isocyanatomethyl)cyclohexane, the content of trans 1,4 isomer is, for example, 60 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 85 mol% or more. In addition, in 1,4-bis(isocyanatomethyl)cyclohexane, the content of trans 1,4 isomer is, for example, 99.8 mol% or less, preferably 99 mol% or less, more preferably 96 mol% or less, and even more preferably 90 mol% or less.

[0025] In 1,4-bis(isocyanatomethyl)cyclohexane, the content of cis-1,4 isomer is, for example, 0.2 mol% or more, preferably 1 mol% or more, more preferably 4 mol% or more, and even more preferably 10 mol% or more. In 1,4-bis(isocyanatomethyl)cyclohexane, the content of cis-1,4 isomer is, for example, 40 mol% or less, preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less.

[0026] When the content of the trans 1,4 isomer and the content of the cis 1,4 isomer are within the above ranges, a polyurethane resin having excellent mechanical strength can be obtained.

[0027] Bis(isocyanatomethyl)cyclohexane is available, for example, as a commercial product. Bis(isocyanatomethyl)cyclohexane can also be produced from bis(aminomethyl)cyclohexane by a known isocyanation method. Examples of the isocyanation method include a cold-hot two-stage phosgenation method, a salt formation method, and a non-phosgene method.

[0028] Furthermore, bis(isocyanatomethyl)cyclohexane may be modified to the extent that the excellent effects of the present invention are not impaired. Examples of modified products include uretdione-modified products, isocyanurate-modified products, iminooxadiazinedione-modified products, biuret-modified products, allophanate-modified products, polyol adducts, oxadiazinetrione-modified products, and carbodiimide-modified products.

[0029] The polyisocyanate component may contain other polyisocyanates (preferably diisocyanates) as optional components within the range that does not impair the excellent effects of the present invention.

[0030] The other polyisocyanates are isocyanates other than bis(isocyanatomethyl)cyclohexane. Examples of the other polyisocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates (other than bis(isocyanatomethyl)cyclohexane), aromatic polyisocyanates, and araliphatic polyisocyanates. Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 1,2-propane diisocyanate, 1,2-butane diisocyanate, 2,3-butane diisocyanate, 1,3-butane diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanatomethyl caproate. Examples of alicyclic polyisocyanates include isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), and methylenebis(cyclohexyl isocyanate) (H 12 Examples of aromatic polyisocyanates include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), toluidine diisocyanate (TODI), paraphenylene diisocyanate, and naphthalene diisocyanate (NDI). Examples of aromatic aliphatic polyisocyanates include xylylene diisocyanate (XDI) and tetramethylxylylene diisocyanate (TMXDI). Furthermore, other polyisocyanates may be modified as described above, provided that the excellent effects of the present invention are not impaired. These may be used alone or in combination of two or more.

[0031] The content of the other polyisocyanates is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 0% by mass, relative to the total amount of the polyisocyanate components. The content of bis(isocyanatomethyl)cyclohexane is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass, relative to the total amount of the polyisocyanate components. That is, the polyisocyanate component is particularly preferably composed of bis(isocyanatomethyl)cyclohexane.

[0032] The polyol component contains a macropolyol as an essential component.

[0033] Macropolyols are organic compounds with two or more hydroxyl groups in the molecule and a relatively high molecular weight. A relatively high molecular weight means that the number average molecular weight exceeds 400.

[0034] Examples of the macropolyol include polyether polyol, polyester polyol, polycarbonate polyol, polyurethane polyol, epoxy polyol, vegetable oil polyol, polyolefin polyol, acrylic polyol, and vinyl monomer-modified polyol. Preferred examples of the macropolyol include polyether polyol, polyester polyol, and polycarbonate polyol.

[0035] Examples of polyether polyols include polyoxyalkylene polyols, such as polyoxyalkylene (C2-3) polyols and polytetramethylene ether polyols.

[0036] Examples of polyester polyols include condensation polyester polyols and ring-opening polyester polyols. Examples of condensation polyester polyols include adipate-based polyester polyols and phthalic acid-based polyester polyols. Examples of ring-opening polyester polyols include lactone-based polyester polyols, more specifically polycaprolactone. La Examples include methacrylate polyols.

[0037] An example of the polycarbonate polyol is a ring-opening polymer of ethylene carbonate using a low-molecular-weight polyol as an initiator, as described below.

[0038] These macropolyols can be used alone or in combination of two or more. From the viewpoint of suppressing the entrapment of air bubbles, the macropolyol is more preferably a polyester polyol, even more preferably a ring-opening polyester polyol, still more preferably a lactone-based polyester polyol, and particularly preferably a polycaprolactone. La In view of mechanical properties, the macropolyol is more preferably a polyether polyol, and even more preferably a polytetramethylene ether polyol.

[0039] The number average molecular weight of the macropolyol exceeds 400, preferably 500 or more, more preferably 650 or more, and even more preferably 1000 or more. The number average molecular weight of the macropolyol is, for example, 5000 or less, preferably 3000 or less, more preferably 2000 or less, and even more preferably 1500 or less. The average number of functional groups (average number of hydroxyl groups) of the macropolyol is, for example, 2 or more. The average number of functional groups (average number of hydroxyl groups) of the macropolyol is, for example, 6 or less, preferably 4 or less, more preferably 3 or less, and even more preferably 2.5 or less.

[0040] The polyol component may optionally include a low molecular weight polyol.

[0041] A low-molecular-weight polyol is an organic compound having two or more hydroxyl groups in the molecule and having a relatively low molecular weight. A relatively low molecular weight means that the number-average molecular weight is 400 or less. That is, the molecular weight of a low-molecular-weight polyol is, for example, 400 or less, preferably 300 or less. The molecular weight of a low-molecular-weight polyol is usually 40 or more.

[0042] Examples of low-molecular-weight polyols include 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. Examples of trihydric alcohols include glycerin and trimethylolpropane. Examples of tetrahydric or higher alcohols include pentaerythritol and diglycerin. Examples of low-molecular-weight polyols include polymers obtained by addition polymerization of alkylene (C2-C3) oxide with dihydric to tetrahydric alcohols to give a number-average molecular weight of 400 or less. These may be used alone or in combination.

[0043] The content of the low molecular weight polyol is, for example, 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less, and particularly preferably 0% by mass, based on the total amount of the polyol components. The content of the macro polyol is, for example, 90% by mass or more, preferably 95% by mass or more, more preferably 99% by mass or more, and particularly preferably 100% by mass, based on the total amount of the polyol components. That is, the polyol component is particularly preferably composed of a macro polyol.

[0044] The isocyanate-terminated prepolymer is synthesized in the first step described below, and then mixed with an isocyanate monomer (described below) in the second step described below, thereby resulting in the isocyanate-terminated prepolymer being contained in the prepolymer composition.

[0045] The content of the isocyanate-terminated prepolymer in the prepolymer composition is appropriately set within a range that does not impair the excellent effects of the present invention. More specifically, the content of the isocyanate-terminated prepolymer relative to the total amount of the prepolymer composition is, for example, 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more. Furthermore, the content of the isocyanate-terminated prepolymer relative to the total amount of the prepolymer composition is, for example, 90% by mass or less, preferably 80% by mass or less, and more preferably 70% by mass or less.

[0046] The weight-average molecular weight of the isocyanate-terminated prepolymer is 7,000 or more, preferably 8,000 or more, and more preferably 9,000 or more. The weight-average molecular weight of the isocyanate-terminated prepolymer is 14,000 or less, preferably 13,000 or less, and more preferably 12,000 or less. The weight-average molecular weight can be measured by known gel permeation chromatography (GPC) (the same applies hereinafter).

[0047] The weight-average molecular weight of the isocyanate-terminated prepolymer is the weight-average molecular weight of the portion of the prepolymer composition described below excluding the isocyanate monomer. That is, in a GPC chart, the peak derived from the isocyanate-terminated prepolymer and the peak derived from the isocyanate monomer are separated, and the molecular weight is calculated as the peak derived from the isocyanate-terminated prepolymer. Details of the GPC measurement conditions are described below in the examples.

[0048] The isocyanate group concentration of the isocyanate group-terminated prepolymer is, for example, 15.0% by mass or more, preferably 15.5% by mass or more, and more preferably 16.0% by mass or more. The isocyanate group concentration of the isocyanate group-terminated prepolymer is, for example, 20.0% by mass or less, preferably 19.5% by mass or less, and more preferably 19.0% by mass or less. The isocyanate group concentration (isocyanate group content) can be determined by known measurement methods. Examples of measurement methods include titration with di-n-butylamine and FT-IR analysis (the same applies below).

[0049] The isocyanate monomer contains the above-mentioned bis(isocyanatomethyl)cyclohexane as an essential component. Preferably, the isocyanate monomer contains the same type of bis(isocyanatomethyl)cyclohexane as the polyisocyanate component used as a raw material for the isocyanate group-terminated prepolymer.

[0050] More specifically, the isocyanate monomer is preferably 1,4-bis(isocyanatomethyl)cyclohexane, and the content ratio of the trans-1,4 isomer and the cis-1,4 isomer in the 1,4-bis(isocyanatomethyl)cyclohexane is preferably within the above-mentioned range.

[0051] The isocyanate monomer may also contain other polyisocyanates as optional components, i.e., isocyanates other than bis(isocyanatomethyl)cyclohexane.

[0052] The content of other polyisocyanates relative to the total amount of isocyanate monomers is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 0% by mass. Furthermore, the content of bis(isocyanatomethyl)cyclohexane relative to the total amount of isocyanate monomers is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass. That is, the isocyanate monomer is particularly preferably composed of bis(isocyanatomethyl)cyclohexane.

[0053] The isocyanate monomer is mixed with the isocyanate group-terminated prepolymer in the second step described below, for example, so that the isocyanate monomer is contained in the prepolymer composition.

[0054] The content of the isocyanate monomer in the prepolymer composition is appropriately set within a range that does not impair the excellent effects of the present invention. More specifically, the content of the isocyanate monomer relative to the total amount of the prepolymer composition is, for example, 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more. Furthermore, the content of the isocyanate monomer relative to the total amount of the prepolymer composition is, for example, 50% by mass or less, preferably 45% by mass or less, and more preferably 40% by mass or less.

[0055] The weight average molecular weight of the prepolymer composition is, for example, 7000 or more, preferably 8000 or more, and more preferably 9000 or more. When the weight average molecular weight of the prepolymer composition is above the lower limit, a polyurethane resin in which entrapment of air bubbles is suppressed can be obtained.

[0056] The weight average molecular weight of the prepolymer composition is, for example, not more than 14,000, preferably not more than 13,000, and more preferably not more than 12,000. When the weight average molecular weight of the prepolymer composition is below the upper limit, a polyurethane resin having excellent mechanical strength (hardness, etc.) can be obtained.

[0057] The isocyanate group concentration of the prepolymer composition is 15.0% by mass or more, preferably 15.5% by mass or more, and more preferably 16.0% by mass or more. When the isocyanate group concentration of the prepolymer composition is above the lower limit, a polyurethane resin having excellent hardness can be obtained.

[0058] The isocyanate group concentration of the prepolymer composition is 20.0% by mass or less, preferably 19.5% by mass or less, and more preferably 19.0% by mass or less. If the isocyanate group concentration of the prepolymer composition is below the upper limit, a polyurethane resin having excellent tensile strength and elongation can be obtained.

[0059] The isocyanate group concentration of the prepolymer composition is measured as the isocyanate group concentration of a mixture containing the isocyanate group-terminated prepolymer and the isocyanate monomer. Measurement methods include, for example, titration with di-n-butylamine and FT-IR analysis.

[0060] The chain extender is a curing agent for the prepolymer composition. Examples of the chain extender include low molecular weight polyols and low molecular weight polyamines. A preferred chain extender is a low molecular weight polyol. By using a low molecular weight polyol, a polyurethane resin having excellent mechanical strength can be obtained.

[0061] Examples of low-molecular-weight polyols include the above-mentioned low-molecular-weight polyols. More specifically, examples of low-molecular-weight polyols include the above-mentioned dihydric alcohols, trihydric alcohols, and tetrahydric or higher alcohols. These can be used alone or in combination of two or more.

[0062] The low-molecular-weight polyol is preferably a dihydric alcohol or a trihydric alcohol, more preferably a dihydric alcohol, and even more preferably 1,4-butanediol. That is, the low-molecular-weight polyol preferably contains 1,4-butanediol, and more preferably consists of 1,4-butanediol. This allows for the production of a polyurethane resin with excellent mechanical strength.

[0063] The method for producing the polyurethane resin will be described in detail below.

[0064] In this method, first, an isocyanate group-terminated prepolymer is synthesized (first step), then a prepolymer composition is prepared (second step), and then a polyurethane resin is synthesized (third step).

[0065] More specifically, in this method, first, the polyisocyanate component and the polyol component are reacted in a predetermined ratio to synthesize an isocyanate group-terminated prepolymer (first step).

[0066] The blending ratio of the polyisocyanate component and the polyol component is adjusted so that the isocyanate groups in the polyisocyanate component are in excess relative to the hydroxyl groups in the polyol component.

[0067] More specifically, in the first step, the equivalent ratio R1(NCO / OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component exceeds 1.0, preferably is 1.1 or more, and more preferably is 1.3 or more. Furthermore, the equivalent ratio R1(NCO / OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component is, for example, 2.5 or less, preferably 2.0 or less. When the blending ratio of the polyisocyanate component to the polyol component is within the above range, the weight-average molecular weight of the isocyanate-terminated prepolymer can be made relatively high.

[0068] In the first step, examples of the reaction method include bulk polymerization and solution polymerization. In bulk polymerization, for example, the polyisocyanate component and the polyol component are reacted under a nitrogen gas flow. The reaction temperature is, for example, 50°C or higher. The reaction temperature is, for example, 250°C or lower, preferably 200°C or lower. The reaction time is, for example, 0.5 hours or higher, preferably 1 hour or higher. The reaction time is, for example, 15 hours or lower. In solution polymerization, the polyisocyanate component and the polyol component are reacted in the presence of a known organic solvent. The reaction temperature is, for example, 50°C or higher. The reaction temperature is, for example, 120°C or lower, preferably 100°C or lower. The reaction time is, for example, 0.5 hours or higher, preferably 1 hour or higher. The reaction time is, for example, 15 hours or lower. If necessary, for example, a known urethanization catalyst can be added. The addition ratio of the urethanization catalyst is appropriately determined depending on the purpose and application.

[0069] This produces a reaction mixture containing an isocyanate-terminated prepolymer. The isocyanate group concentration in the reaction mixture is, for example, 2.0% by mass or more, preferably 3.0% by mass or more. The isocyanate group concentration in the reaction mixture is, for example, 6.0% by mass or less, preferably 5.0% by mass or less. If necessary, unreacted polyisocyanate components can be removed from the reaction mixture by a known method.

[0070] Next, in this method, the reaction mixture containing the isocyanate group-terminated prepolymer is mixed with the isocyanate monomer to prepare a prepolymer composition (second step).

[0071] The blending ratio of the isocyanate group-terminated prepolymer and the isocyanate monomer is adjusted so that the isocyanate group concentration of the prepolymer composition falls within the above range.

[0072] More specifically, the equivalent ratio R2(NCO / OH) of the total amount of isocyanate groups of the polyisocyanate component used in the first step and the isocyanate groups of the isocyanate monomer used in the second step to the hydroxyl groups in the polyol component used in the first step is, for example, 3.0 or more, preferably 4.0 or more. Also, the equivalent ratio R2(NCO / OH) of the total amount of isocyanate groups of the polyisocyanate component used in the first step and the isocyanate groups of the isocyanate monomer used in the second step to the hydroxyl groups in the polyol component used in the first step is, for example, 10.0 or less, preferably 6.0 or less, more preferably 5.5 or less.

[0073] This prepares a prepolymer composition containing an isocyanate group-terminated prepolymer and an isocyanate monomer containing bis(isocyanatomethyl)cyclohexane.

[0074] In the prepolymer composition, the ratio of the isocyanate group-terminated prepolymer to the isocyanate monomer is, for example, within the above-mentioned range. The weight average molecular weight of the isocyanate group-terminated prepolymer is also within the above-mentioned range. The isocyanate group concentration of the prepolymer composition is also within the above-mentioned range.

[0075] Thereafter, in this method, the prepolymer composition is reacted with a chain extender (third step).

[0076] More specifically, the blending ratio of the prepolymer composition and the chain extender is such that the equivalent ratio R3(NCO / OH) of the isocyanate groups in the prepolymer composition to the hydroxyl groups in the chain extender (low molecular weight polyol) is, for example, 0.90 or more, preferably 1.00 or more, and the equivalent ratio R3(NCO / OH) of the isocyanate groups in the prepolymer composition to the hydroxyl groups in the chain extender (low molecular weight polyol) is, for example, 1.33 or less, preferably 1.25 or less.

[0077] In the third step, examples of the reaction method include the bulk polymerization and solution polymerization. In bulk polymerization, the reaction temperature is, for example, 50°C or higher, preferably 100°C or higher, and more preferably 120°C or higher. The reaction temperature is, for example, 250°C or lower, preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 150°C or lower. The reaction time is, for example, 0.5 hours or higher, preferably 1 hour or higher. The reaction time is, for example, 24 hours or lower, preferably 20 hours or lower, and more preferably 18 hours or lower. In solution polymerization, the reaction temperature is, for example, 50°C or higher. The reaction temperature is, for example, 120°C or lower, preferably 100°C or lower. The reaction time is, for example, 0.5 hours or higher, preferably 1 hour or higher. The reaction time is, for example, 24 hours or lower. If necessary, for example, a known urethane catalyst can be added. The proportion of the urethanization catalyst added is appropriately determined depending on the purpose and application.

[0078] This results in a polyurethane resin containing a reaction product of the prepolymer composition and the chain extender. Preferably, the mixture of the prepolymer composition and the chain extender is degassed as needed, cured in a preheated mold, and then demolded. This results in a polyurethane resin molded into a desired shape.

[0079] The polyurethane resin can also be heat-treated. The heat treatment temperature is, for example, 50°C or higher, preferably 80°C or higher. The heat treatment temperature is, for example, 200°C or lower, preferably 150°C or lower. The heat treatment time is, for example, 30 minutes or longer, preferably 1 hour or longer. The heat treatment time is, for example, 30 hours or shorter, preferably 20 hours or shorter.

[0080] The polyurethane resin can be cured. The curing temperature is, for example, 10°C or higher, preferably 20°C or higher. The curing temperature is, for example, 50°C or lower, preferably 40°C or lower. The curing time is, for example, 1 hour or longer, preferably 10 hours or longer. The curing time is, for example, 50 days or shorter, preferably 30 days or shorter.

[0081] The polyurethane resin may contain known additives as needed. That is, the polyurethane resin may be a polyurethane resin composition. Examples of additives include antioxidants, heat stabilizers, light stabilizers, UV absorbers, antiblocking agents, mold release agents, pigments, dyes, lubricants, fillers, hydrolysis inhibitors, rust inhibitors, and bluing agents. The amount and timing of addition of the additives are appropriately determined depending on the purpose and application.

[0082] The polyurethane resin has excellent mechanical strength and can suppress the entrapment of air bubbles.

[0083] That is, in the above polyurethane resin, the prepolymer composition includes an isocyanate-terminated prepolymer and an isocyanate monomer. The isocyanate-terminated prepolymer includes a reaction product of a polyisocyanate component including bis(isocyanatomethyl)cyclohexane and a polyol component including a macropolyol. The isocyanate monomer includes bis(isocyanatomethyl)cyclohexane. The isocyanate-terminated prepolymer has a weight-average molecular weight within a predetermined range. The prepolymer composition has an isocyanate group concentration within a predetermined range. That is, the prepolymer composition includes an isocyanate-terminated prepolymer with a relatively high weight-average molecular weight and bis(isocyanatomethyl)cyclohexane, and the prepolymer composition has a relatively high isocyanate group concentration.

[0084] Therefore, the polyurethane resin has excellent mechanical strength and can suppress entrapment of air bubbles. More specifically, in the polyurethane resin, the prepolymer composition contains an isocyanate monomer and has a relatively high isocyanate group concentration, so that the hard segment concentration of the polyurethane resin can be relatively high, thereby improving the mechanical strength. Furthermore, in the polyurethane resin, the weight-average molecular weight of the isocyanate group-terminated prepolymer is relatively high, so that the viscosity of the prepolymer composition is relatively high, and thus entrapment of air bubbles can be suppressed.

[0085] In the above-mentioned polyurethane resin production method, a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane is first reacted with a polyol component containing a macropolyol at an equivalent ratio (NCO / OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component exceeding 1.0 to synthesize an isocyanate-terminated prepolymer. That is, in this first step, an isocyanate-terminated prepolymer having a relatively high weight-average molecular weight is obtained.

[0086] In the method for producing the polyurethane resin, the isocyanate-terminated prepolymer is then mixed with an isocyanate monomer containing bis(isocyanatomethyl)cyclohexane to prepare a prepolymer composition containing the isocyanate-terminated prepolymer and the isocyanate monomer. That is, in this second step, a prepolymer composition having a relatively high isocyanate group concentration is obtained.

[0087] In the method for producing a polyurethane resin, the prepolymer composition is then reacted with a chain extender to obtain a polyurethane resin in the third step.

[0088] According to such a method, a polyurethane resin having excellent mechanical strength can be obtained, and the inclusion of air bubbles in the polyurethane resin can be suppressed.

[0089] In particular, when the first and second steps are combined into one process to produce a prepolymer composition, simply adding a large excess of the polyisocyanate component relative to the polyol component results in a low weight-average molecular weight of the isocyanate-terminated prepolymer. This results in a relatively low viscosity of the prepolymer composition. As a result, it is not possible to suppress the entrapment of air bubbles in the polyurethane resin.

[0090] In contrast, in the above-mentioned method, the weight-average molecular weight of the isocyanate-terminated prepolymer is relatively high, and therefore the viscosity of the prepolymer composition is relatively high, which makes it possible to suppress the entrapment of air bubbles in the polyurethane resin.

[0091] The prepolymer composition includes an isocyanate-terminated prepolymer and an isocyanate monomer. The isocyanate-terminated prepolymer includes a reaction product of a polyisocyanate component including bis(isocyanatomethyl)cyclohexane and a polyol component including a macropolyol. The isocyanate monomer includes bis(isocyanatomethyl)cyclohexane. The weight-average molecular weight of the isocyanate-terminated prepolymer is within a predetermined range, and the prepolymer composition has an isocyanate group concentration within a predetermined range.

[0092] Therefore, the prepolymer composition can provide a polyurethane resin having excellent mechanical strength, and can also suppress the entrapment of air bubbles in the polyurethane resin.

[0093] As a result, the polyurethane resin and prepolymer composition described above are suitable for use in various industrial fields that require mechanical strength and suppression of entrapped air bubbles. Such industrial fields include, for example, elastic molded products, paints, coating agents, and adhesives. Elastic molded products are preferred.

[0094] Examples of the elastic molded article include polyurethane elastomers. Examples of polyurethane elastomers include TPU (thermoplastic polyurethane resin) and TSU (thermosetting polyurethane resin). Examples of the elastic molded article preferably include TSU (thermosetting polyurethane resin).

[0095] Elastic molded articles can be obtained by molding polyurethane resins using known molding methods, such as cast molding, thermocompression molding, injection molding, extrusion molding, and spinning. The molded shapes can be, for example, plates, fibers, strands, films, sheets, pipes, bottles, hollow bodies, boxes, and buttons.

[0096] Such elastic molded articles contain the polyurethane resin described above, and therefore have excellent mechanical strength and are able to suppress the inclusion of air bubbles, making them suitable for a variety of uses. Applications of elastic molded products include, for example, transparent hard plastics, waterproofing materials, potting agents, inks, binders, films, sheets, bands, belts, shoe press belts, tubes, blades, speakers, sensors, outsoles, yarns, fibers, nonwoven fabrics, cosmetics, shoe supplies, heat insulation materials, sealing materials, tapes, encapsulants, solar power generation components, robot components, android components, wearable components, clothing supplies, sanitary products, cosmetics, furniture supplies, food packaging components, sporting goods, leisure goods, medical supplies, nursing care products, housing components, acoustic components, lighting components, vibration-damping components, soundproofing components, daily necessities, miscellaneous goods, cushions, bedding, stress absorbing materials, stress relaxation materials, automotive interior materials, automotive exterior materials, railway components, aircraft components, optical components, office equipment components, miscellaneous goods surface protection materials, semiconductor encapsulants, self-repairing materials, health appliances, eyeglass lenses, toys, packing, cable sheaths, wire harnesses, telecommunications cables, automotive wiring, computer wiring, industrial products, shock absorbing materials, semiconductor products, and bridge bearings. [Example]

[0097] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited thereto. Note that "parts" and "%" are by mass unless otherwise specified. Furthermore, specific numerical values such as blending ratios (content ratios), physical property values, and parameters used in the following description can be substituted with the corresponding upper limit values (numeric values defined as "equal to or less than") or lower limit values (numeric values defined as "equal to or more than" or "exceeding") of the blending ratios (content ratios), physical property values, parameters, etc. described in the above "Modes for Carrying Out the Invention."

[0098] 1. Raw materials <Polyisocyanate component, isocyanate monomer> Preparation Example 1 1,4-bis(isocyanatomethyl)cyclohexane 1,4-bis(isocyanatomethyl)cyclohexane (1,4-H6XDI) was obtained in accordance with the description of Production Example 3 in International Publication WO2019 / 069802. The purity of 1,4-H6XDI was measured by gas chromatography and found to be 99.9%. The color was measured by APHA and found to be 5. 13 The ratio of trans isomer to cis isomer measured by C-NMR was 86 mol % of the trans isomer and 14 mol % of the cis isomer.

[0099] <Polyol component> PTMEG-650: Polytetramethylene ether glycol, number average molecular weight (Mn) 650 PTMEG-1000: Polytetramethylene ether glycol, number average molecular weight (Mn) 1000 PTMEG-2000: Polytetramethylene ether glycol, number average molecular weight (Mn) 2000 PTMEG-3000: Polytetramethylene ether glycol, number average molecular weight (Mn) 3000 PCL-1000: Polycarbonate La Dimethicone, number average molecular weight (Mn) 1000 PCL-2000: Polycarbonate LaDimethicone, number average molecular weight (Mn) 2000

[0100] <Chain extender> 1,4-BD: 1,4-butanediol

[0101] 2. Prepolymer composition and polyurethane resin Examples 1 to 5 and Comparative Examples 1 to 8 (1) First step The polyisocyanate component and the polyol component were reacted under a nitrogen atmosphere according to the formulation and conditions shown in Table 1. The following additives were then added to the reaction mixture. The amounts of the additives relative to the total amount of the reaction mixture are shown below. Tin octoate (urethane catalyst) 0.0005% by mass Diisononyl adipate (diluent for stannous octoate) 0.012% by mass Tridecyl phosphite (antioxidant) 0.002% by mass

[0102] This resulted in a reaction mixture containing an isocyanate-terminated prepolymer. In Table 1, the equivalent ratio R1 indicates the equivalent ratio R1(NCO / OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component.

[0103] (2)Second process An isocyanate monomer was added to the reaction mixture according to the formulation shown in Table 1 to obtain a prepolymer composition. The following additives were then added to the reaction mixture. The amounts of the additives relative to the total amount of the reaction mixture are shown below. The proportions of the isocyanate-terminated prepolymer and the isocyanate monomer in the prepolymer composition were calculated based on the charge ratios. The results are shown in the table. Hindered amine antioxidant 0.50% by mass Phosphite ester antioxidant 0.30% by mass

[0104] In Table 1, the equivalent ratio R2 indicates the equivalent ratio (NCO / OH) of the total amount of isocyanate groups of the polyisocyanate component used in the first step and the isocyanate groups of the isocyanate monomer used in the second step, relative to the hydroxyl groups in the polyol component used in the first step. In Comparative Examples 1 to 4, the second step was omitted.

[0105] (3) Third step A prepolymer composition and a chain extender were prepared according to the formulations shown in Table 1 and heated to 60°C. The following additives were added to the prepolymer composition and mixed for 60 seconds. The amounts of the additives added relative to the polyurethane resin are shown below. Tin octylate (urethane catalyst) 0.03 parts by weight / 100 parts by weight of polyurethane resin Diisononyl adipate (diluent for stannous octoate) 1.47 parts by weight / 100 parts by weight of polyurethane resin Adekastab LA-72 (ADEKA Corporation, light resistance stabilizer) 0.3 parts by weight / Polyurethane resin 100 parts by weight The prepolymer composition and the chain extender were mixed for 60 seconds and degassed under reduced pressure at room temperature for 60 seconds. The mixture was then poured into a mold at 110°C and reacted at 110°C for 16 hours, and then aged at 23°C for 3 weeks. This yielded a polyurethane resin. In Example 5, the reaction temperature was 135° C. and the reaction time was 4 hours.

[0106] 3. Evaluation <Prepolymer composition> (1) Weight average molecular weight The prepolymer composition was subjected to GPC measurement using a gel permeation chromatograph equipped with a differential refractometer, and the weight-average molecular weight of the isocyanate-terminated prepolymer was measured based on the results. That is, in the GPC chart, the peak attributable to the isocyanate-terminated prepolymer and the peak attributable to the isocyanate monomer were separated, and the weight-average molecular weight of the peak attributable to the isocyanate-terminated prepolymer was calculated. In comparative examples in which the second step was omitted, the weight-average molecular weight of the reaction solution from the first step was measured instead of the prepolymer composition.

[0107] Specifically, 0.05 g of the prepolymer composition (sample) was dissolved in 1 to 2 mL of methanol in a glass bottle and left at room temperature for about three days. This resulted in the sample being converted into methyl urethane. If the sample was not soluble in methanol, dichloromethane (cosolvent) was added to dissolve the sample.

[0108] The sample was then heated to 50°C while blowing N2 onto it to volatilize the solvent containing methanol. This resulted in a solid sample. The sample was dissolved in N,N'-dimethylformamide (DMF) to obtain a 0.625% by mass solution. The resulting solution was subjected to GPC measurement under the following conditions.

[0109] (1) Analytical equipment: HLC-8220GPC (Tosoh Corporation) (2) Pump: Attached to the device (3) Detector: Attached to the device: RI detector (4) Eluent: DMF (LiBr 0.86g / L) (5) Separation column: SuperAWM-H x 3 Manufacturer: Tosoh Corporation Product code: 19320 (6) Measurement temperature: 40℃ (7) Flow rate: Sample pump 0.6 mL / min, reference pump 0.6 mL / min (8) Sample injection volume: 20 μL (9) Analysis equipment: Analysis software GPC-8020mII (Tosoh Corporation) System correction (10) Standard material name: Polystyrene

[0110] (2) Isocyanate group concentration The isocyanate group concentration of the prepolymer composition was measured in accordance with the n-dibutylamine method of JIS K 1556 (2006). In a comparative example in which the second step was omitted, the isocyanate group concentration of the reaction liquid of the first step was measured instead of the prepolymer composition.

[0111] (3) Viscosity The viscosity of the prepolymer composition at 60°C was measured using a cone-plate viscometer in accordance with JIS K 5600-2-3 (2014) at a temperature of 60°C, a 40P plate, and a rotation speed of 188 rpm.

[0112] <Polyurethane resin> (1)D hardness The Shore D hardness of the polyurethane resin was measured in accordance with JIS K 7312 (1996).

[0113] (2) Tensile properties The tensile properties of the polyurethane resin were measured using a universal tensile tester (Intesco 205N) in accordance with JIS K 7312 (1996). Specifically, the polyurethane resin was cut to obtain No. 3 dumbbell-shaped test pieces. The 100% to 300% modulus (MPa), tensile strength (MPa), and elongation at break (%) were measured at a tension speed of 500 mm / min.

[0114] (3) Compression set The compression set of the polyurethane resin was measured in accordance with JIS K 7312 (1996).

[0115] (4) Air bubbles trapped in the molded body The polyurethane resin was visually inspected to evaluate whether or not air bubbles had been trapped. The evaluation criteria are as follows: There were 11 or more visible bubbles within a 1:5 cm cube. 2: There were 6 to 10 visible bubbles within a 5 cm cube. 3: There were 3 to 5 visible bubbles within a 5 cm cube. 4: There were one to two visible air bubbles within a 5 cm cube. 5: There were no visible air bubbles within the 5cm cube.

[0116] [Table 1]

Claims

1. comprising the reaction product of a prepolymer composition and a chain extender; the prepolymer composition comprises an isocyanate group-terminated prepolymer and an isocyanate monomer; The isocyanate-terminated prepolymer comprises a reaction product of a polyisocyanate component including bis(isocyanatomethyl)cyclohexane and a polyol component including a macropolyol having a number average molecular weight of more than 400; the isocyanate monomer comprises bis(isocyanatomethyl)cyclohexane; the weight average molecular weight of the isocyanate group-terminated prepolymer is 7,000 or more and 14,000 or less; The polyurethane resin, wherein the prepolymer composition has an isocyanate group concentration of 15.0% by mass or more and 20.0% by mass or less.

2. An elastic molded article comprising the polyurethane resin of claim 1.

3. A method for producing the polyurethane resin of claim 1, comprising: a first step of synthesizing an isocyanate-terminated prepolymer by reacting a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane with a polyol component containing a macropolyol having a number average molecular weight of more than 400 at an equivalent ratio (NCO / OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component of more than 1.0; a second step of mixing the isocyanate group-terminated prepolymer with an isocyanate monomer including bis(isocyanatomethyl)cyclohexane to prepare a prepolymer composition including the isocyanate group-terminated prepolymer and the isocyanate monomer; a third step of reacting the prepolymer composition with a chain extender to synthesize a polyurethane resin; A method for producing a polyurethane resin, comprising:

4. It contains an isocyanate group-terminated prepolymer and an isocyanate monomer, The isocyanate-terminated prepolymer comprises a reaction product of a polyisocyanate component including bis(isocyanatomethyl)cyclohexane and a polyol component including a macropolyol having a number average molecular weight of more than 400; the weight average molecular weight of the isocyanate group-terminated prepolymer is 7,000 or more and 14,000 or less; the isocyanate monomer comprises bis(isocyanatomethyl)cyclohexane; A prepolymer composition having an isocyanate group concentration of 15.0% by mass or more and 20.0% by mass or less.

Images