Polyurethane resin manufacturing method

Abstract

To provide a method for producing a polyurethane resin for producing a polyurethane elastomer having both excellent mechanical properties and excellent appearance.SOLUTION: A polyurethane resin is synthesized by reacting, in a ratio that an equivalent ratio (NCO / OH) exceeds 1.0, a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane and a polyol component containing macropolyol, to obtain a prepolymer composition containing an isocyanate group terminal prepolymer, and reacting the prepolymer composition with a chain extender. In a prepolymer preparation step and / or chain extension step, an organic tin catalyst is added, and a ratio of the organic tin catalyst is 50 ppm or more with respect to the total amount of the prepolymer composition, in the chain extension step, a temperature of the prepolymer composition is lower than 80°C, and an equivalent ration (NCO / active hydrogen group) is 1.01-1.42, and a reaction temperature of the prepolymer composition and the chain extender is 100-140°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a polyurethane resin. [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 and polytetramethylene ether glycol are reacted to obtain an isocyanate-terminated prepolymer. Next, 150 parts by mass of the isocyanate-terminated prepolymer and 7.62 to 8.71 parts by mass of 1,4-butylene glycol are preheated to 80°C and mixed. The equivalent ratio (NCO / active hydrogen groups) is 1.12 to 1.28. Furthermore, 0.0008 parts by mass of dibutyltin dilaurate is added to the mixture, which is then poured into a mold and cured at 110°C for 24 hours to obtain a polyurethane elastomer (see, for example, Patent Document 1 (Synthesis Example 1 and Examples 1 to 5)). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-231585 Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned method for producing a polyurethane elastomer can provide a polyurethane elastomer having excellent mechanical properties.

[0006] However, in the above-mentioned method for producing a polyurethane elastomer, the temperature of the isocyanate-terminated prepolymer is high, so the surface of the polyurethane elastomer cures relatively quickly, while the amount of catalyst added is relatively small, so the interior of the polyurethane elastomer cures relatively slowly.

[0007] As a result, in the above-mentioned method for producing a polyurethane elastomer, uneven curing of the polyurethane elastomer occurs, and the surface of the polyurethane elastomer may peel off when demolded, resulting in poor appearance.

[0008] The present invention is a method for producing a polyurethane resin that has both excellent mechanical properties and an excellent appearance. [Means for solving the problem]

[0009] The present invention [1] comprises a prepolymer preparation step in which a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane is 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 exceeds 1.0 to obtain a prepolymer composition containing an isocyanate group-terminated prepolymer, and a chain extension step in which the prepolymer composition is reacted with a chain extender to synthesize a polyurethane resin, and the prepolymer preparation step and / or or a method for producing a polyurethane resin, wherein in the chain extension step, an organotin catalyst is added and the proportion of the organotin catalyst is 50 ppm or more relative to the total amount of the prepolymer composition; in the chain extension step, the temperature of the prepolymer composition is less than 80°C; the equivalent ratio of the isocyanate groups in the prepolymer composition to the active hydrogen groups in the chain extender (NCO / active hydrogen groups) is 1.01 or more and 1.42 or less; and the reaction temperature of the prepolymer composition and the chain extender is 100°C or more and 140°C or less.

[0010] The present invention [2] includes the method for producing a polyurethane resin according to the above [1], wherein the bis(isocyanatomethyl)cyclohexane includes 1,4-bis(isocyanatomethyl)cyclohexane.

[0011] The present invention [3] includes the method for producing a polyurethane resin according to the above [1] or [2], wherein the bis(isocyanatomethyl)cyclohexane includes trans-1,4-bis(isocyanatomethyl)cyclohexane. [Effects of the Invention]

[0012] In the method for producing a polyurethane resin of the present invention, the temperature of the isocyanate-terminated prepolymer is relatively low in the chain extension step, thereby suppressing the curing rate of the surface of the polyurethane resin, and the proportion of the organotin catalyst is relatively high, thereby improving the curing rate inside the polyurethane resin. In addition, the equivalent ratio (NCO / active hydrogen group) and reaction temperature in the chain extension step are adjusted within predetermined ranges.

[0013] Therefore, in the method for producing a polyurethane resin of the present invention, uneven curing is suppressed, and as a result, a polyurethane resin having both excellent mechanical properties and excellent appearance can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0014] In the method for producing a polyurethane resin of the present invention, first, a polyisocyanate component and a polyol component are reacted to prepare a prepolymer composition. Next, the prepolymer composition is reacted with a chain extender (described later) to produce a polyurethane resin. Each step will be described in detail below.

[0015] (1) Prepolymer preparation process In this method, first, a polyisocyanate component and a polyol component are reacted in a predetermined ratio to prepare a prepolymer composition containing an isocyanate group-terminated prepolymer (prepolymer preparation step).

[0016] 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 properties, low-temperature softening property, and low heat generation property of the polyurethane resin, 1,4-bis(isocyanatomethyl)cyclohexane, which has a symmetrical structure, is preferably used. That is, the bis(isocyanatomethyl)cyclohexane preferably contains 1,4-bis(isocyanatomethyl)cyclohexane.

[0017] 1,4-bis(isocyanatomethyl)cyclohexane has cis-1,4-bis(isocyanatomethyl)cyclohexane and trans-1,4-bis(isocyanatomethyl)cyclohexane as stereoisomers. That is, bis(isocyanatomethyl)cyclohexane preferably contains 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. Furthermore, 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%.

[0018] 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.

[0019] 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.

[0020] 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 properties can be obtained.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] The other polyisocyanates are isocyanates other than bis(isocyanatomethyl)cyclohexane. Examples of the other polyisocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates (excluding bis(isocyanatomethyl)cyclohexane), aromatic polyisocyanates, and araliphatic polyisocyanates. Examples of the aliphatic polyisocyanates include pentamethylene diisocyanate (PDI) and hexamethylene diisocyanate (HDI). Examples of the alicyclic polyisocyanates include isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), and methylenebis(cyclohexylisocyanate) (HDI). 12 Examples of aromatic polyisocyanates include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), toluidine diisocyanate (TODI), 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.

[0025] The content of the other polyisocyanates is, from the viewpoint of mechanical properties, 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. Furthermore, from the viewpoint of mechanical properties, the content of bis(isocyanatomethyl)cyclohexane is, from the viewpoint of mechanical properties, 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.

[0026] The polyol component contains a macropolyol as an essential component.

[0027] Macropolyols are organic compounds having two or more hydroxyl groups in the molecule and having a relatively high molecular weight, where a number average molecular weight of more than 400, preferably 500 or more, is used.

[0028] 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.

[0029] Examples of polyether polyols include polyoxyalkylene polyols, such as polyoxyalkylene (C2-3) polyols and polytetramethylene ether polyols.

[0030] 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.

[0031] 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.

[0032] These macropolyols can be used alone or in combination of two or more.

[0033] From the viewpoint of resistance to oxidation and deterioration, 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 Examples include methacrylate polyols.

[0034] Furthermore, from the viewpoint of lowering the glass transition temperature and improving the low-temperature softening property, the macropolyol is more preferably a polyether polyol, and even more preferably a polytetramethylene ether polyol.

[0035] 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, and more preferably 2000 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. The average number of functional groups (average number of hydroxyl groups) of the macropolyol is most preferably 2.

[0036] The polyol component may optionally include a low molecular weight polyol.

[0037] 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, preferably 300 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] More specifically, in the prepolymer preparation 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 1.1 or more, more preferably 1.3 or more, and 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.

[0042] In the prepolymer preparation process, reaction methods include, for example, bulk polymerization and solution polymerization.

[0043] In bulk polymerization, for example, a polyisocyanate component and a 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 longer, preferably 1 hour or longer. The reaction time is, for example, 15 hours or shorter.

[0044] 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. 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 longer, preferably 1 hour or longer. The reaction time is, for example, 15 hours or shorter.

[0045] In the prepolymer preparation step, the above reaction is carried out until the isocyanate group concentration (NCO%) of the resulting prepolymer composition reaches a predetermined value (described below).

[0046] In the prepolymer preparation step, a urethanization catalyst may be added, as will be described later.

[0047] As a result, a prepolymer composition is obtained as a reaction product liquid between the polyisocyanate component and the polyol component.

[0048] The prepolymer composition (liquid reaction product) contains, for example, an isocyanate-terminated prepolymer, which is a reaction product of a polyisocyanate component and a polyol component, and the polyisocyanate component, which is an unreacted raw material.

[0049] In the prepolymer composition, the content of the isocyanate group-terminated prepolymer (reaction product) and the content of the unreacted polyisocyanate component (unreacted raw material) are not particularly limited as long as they are within the range of the isocyanate group concentration described below.

[0050] If necessary, a portion of the unreacted polyisocyanate component (unreacted raw material) can be removed from the prepolymer composition by a known method. If necessary, the unreacted polyisocyanate component (unreacted raw material) can be further added to the prepolymer composition.

[0051] The isocyanate group concentration of the prepolymer composition is, for example, 1% by mass or more, preferably 3% by mass or more, and more preferably 5% by mass or more. The isocyanate group concentration of the prepolymer composition is, for example, 20% by mass or less, preferably 15% by mass or less, and more preferably 10% by mass or less. The isocyanate group concentration (isocyanate group content) can be determined by a known measurement method. Examples of measurement methods include titration with di-n-butylamine and FT-IR analysis (the same applies below).

[0052] (2) Chain elongation process Next, in this method, the prepolymer composition is reacted with a chain extender to synthesize a polyurethane resin (chain extension step).

[0053] The chain extender is a curing agent for the prepolymer composition. Examples of the chain extender include low-molecular-weight compounds containing multiple (preferably two) active hydrogen groups (hydroxyl groups, amino groups). More specifically, low-molecular-weight compounds include low-molecular-weight polyols and low-molecular-weight polyamines. A preferred chain extender is low-molecular-weight polyol. By using a low-molecular-weight polyol, a polyurethane resin with excellent mechanical properties can be obtained.

[0054] 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.

[0055] 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 properties.

[0056] The blending ratio of the prepolymer composition and the chain extender is such that the equivalent ratio R2 (NCO / active hydrogen groups) of the isocyanate groups in the prepolymer composition to the active hydrogen groups in the chain extender is 1.01 or more, preferably 1.05 or more, more preferably 1.10 or more, and particularly preferably 1.20 or more. Also, the equivalent ratio R2 (NCO / active hydrogen groups) of the isocyanate groups in the prepolymer composition to the active hydrogen groups in the chain extender is 1.42 or less, preferably 1.35 or less, and more preferably 1.30 or less.

[0057] When the equivalent ratio (NCO / active hydrogen group) in the chain extension step is within the above range, a polyurethane resin having excellent mechanical properties (especially tensile properties and abrasion resistance) and excellent appearance can be obtained.

[0058] In the chain extension step, the temperature of the prepolymer composition is adjusted to be below a predetermined temperature before the prepolymer composition and the chain extender are mixed. Preferably, the temperature of the prepolymer composition is adjusted by heating (preheating).

[0059] In the chain extension step, the temperature of the prepolymer composition is less than 80° C., preferably 75° C. or less, more preferably 70° C. or less. The temperature of the prepolymer composition is, for example, 30° C. or more, preferably 40° C. or more, more preferably 50° C. or more.

[0060] In the chain extension step, if the temperature of the prepolymer composition is below the above upper limit, uneven curing is suppressed, and as a result, a polyurethane resin having both excellent mechanical properties and excellent appearance is obtained.

[0061] In the chain extension step, the temperature of the prepolymer composition is preferably lower than the reaction temperature (curing temperature) described below. The difference between the temperature of the prepolymer composition and the reaction temperature (curing temperature) is, for example, 10°C or more, preferably 20°C or more, and more preferably 30°C or more. The difference between the temperature of the prepolymer composition and the reaction temperature (curing temperature) is, for example, 100°C or less, preferably 90°C or less, and more preferably 80°C or less.

[0062] In the chain extension step, the temperature of the chain extender is also preferably adjusted to be below a predetermined temperature before the prepolymer composition and the chain extender are mixed together. Preferably, the temperature of the chain extender is adjusted by heating (preheating).

[0063] In the chain extension step, the temperature of the chain extender is, for example, less than 80° C., preferably 70° C. or less, more preferably 50° C. or less. The temperature of the chain extender is, for example, 25° C. or more, preferably 30° C. or more, more preferably 35° C. or more.

[0064] In the chain extension step, if the temperature of the chain extender is below the above upper limit, uneven curing is further suppressed, and as a result, a polyurethane resin having both excellent mechanical properties and excellent appearance can be obtained.

[0065] In the chain extension step, the temperature of the chain extender is preferably lower than the reaction temperature (curing temperature) described below. The difference between the temperature of the chain extender and the reaction temperature (curing temperature) is, for example, 20°C or more, preferably 30°C or more, and more preferably 40°C or more. The difference between the temperature of the prepolymer composition and the reaction temperature (curing temperature) is, for example, 120°C or less, preferably 110°C or less, and more preferably 100°C or less.

[0066] Furthermore, in the chain extension step, the temperature of the chain extender (after preheating) is preferably lower than the temperature of the prepolymer composition (after preheating). The difference between the temperature of the chain extender and the temperature of the prepolymer composition is, for example, 5°C or more, preferably 10°C or more, and more preferably 15°C or more. The difference between the temperature of the chain extender and the temperature of the prepolymer composition is, for example, 80°C or less, preferably 60°C or less, and more preferably 40°C or less.

[0067] In the chain extension step, for example, the prepolymer composition and the chain extender are mixed in the above-mentioned ratio and heated to obtain a polyurethane resin containing a reaction product of the prepolymer composition and the chain extender.

[0068] The reaction temperature (curing temperature) in the chain extension step is 100°C or higher, preferably 105°C or higher, and more preferably 110°C or higher.

[0069] When the reaction temperature in the chain extension step is above the lower limit, unevenness in curing is suppressed, and as a result, a polyurethane resin having both excellent mechanical properties and excellent appearance is obtained.

[0070] The reaction temperature (curing temperature) in the chain extension step is 140°C or lower, preferably 138°C or lower, and more preferably 135°C or lower.

[0071] If the reaction temperature in the chain extension step is below the above upper limit, an appropriate curing time can be ensured, and as a result, a polyurethane resin having both excellent mechanical properties and excellent appearance can be obtained.

[0072] The reaction time (curing time) in the chain extension step is, for example, 0.5 hours or more, preferably 1 hour or more, and for example, 24 hours or less, preferably 20 hours or less, more preferably 18 hours or less.

[0073] If the reaction time in the chain extension step is within the above range, unevenness in curing is further suppressed, and as a result, a polyurethane resin having both excellent mechanical properties and excellent appearance can be obtained.

[0074] In particular, from the viewpoint of tensile properties, the reaction temperature is relatively low and the reaction time is relatively long. More specifically, from the viewpoint of tensile properties, the reaction temperature is more preferably 130° C. or less, and particularly preferably 120° C. or less. The reaction time is more preferably 5 hours or more, and particularly preferably 10 hours or more.

[0075] From the viewpoint of wear resistance, the reaction temperature is relatively high and the reaction time is relatively short. More specifically, from the viewpoint of wear resistance, the reaction temperature is more preferably 120° C. or higher, and particularly preferably 125° C. or higher. The reaction time is more preferably 10 hours or shorter, and particularly preferably 6 hours or shorter.

[0076] In the chain extension step, a urethanization catalyst may be added, which will be described later.

[0077] When the polyurethane resin is a polyurethane elastomer, the mixture of the prepolymer composition and the chain extender is preferably degassed as necessary, heat-cured in a preheated mold, and then demolded to obtain a cast polyurethane elastomer molded into a desired shape as the polyurethane resin in the chain extension step.

[0078] In this method, the polyurethane resin can be heat-treated as needed. 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.

[0079] 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.

[0080] 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 of additive added is appropriately determined depending on the purpose and application.

[0081] The timing of adding the additives is not particularly limited. For example, the additives can be added to the polyisocyanate component and / or the polyol component in the prepolymer preparation process. Alternatively, the additives can be added when the polyisocyanate component and the polyol component are mixed in the prepolymer preparation process. Alternatively, the additives can be added to the mixture (reaction mixture) of the polyisocyanate component and the polyol component.

[0082] In the chain extension step, additives can be added to the prepolymer composition and / or the chain extender, or when the prepolymer composition and the chain extender are mixed in the chain extension step.

[0083] The polyurethane resin obtained by the above method includes a reaction product of a prepolymer composition and a chain extender, and preferably consists of a reaction product of a prepolymer composition and a chain extender. That is, the polyurethane resin is preferably a cured urethane product obtained by reacting and curing the prepolymer composition and the chain extender.

[0084] (3) Urethane catalyst In the above-mentioned method for producing a polyurethane resin, a urethanization catalyst is added in either or both of the prepolymer preparation step and the chain extension step.

[0085] The urethane catalyst contains an organotin catalyst as an essential component, that is, the organotin catalyst is added in the prepolymer preparation step and / or the chain extension step.

[0086] Examples of organotin catalysts include tin acetate, tin octoate, tin oleate, tin laurate, monobutyltin trioctoate, dibutyltin diacetate, dimethyltin dilaurate, dibutyltin dilaurate, dibutyltin dimercaptide, dibutyltin maleate, dibutyltin dineodecanoate, dioctyltin dimercaptide, dioctyltin dilaurate, and dibutyltin dichloride. These can be used alone or in combination of two or more. A preferred organotin catalyst is dibutyltin dilaurate.

[0087] The amount of the organotin catalyst added is adjusted as a mass ratio relative to the prepolymer composition (including the isocyanate group-terminated prepolymer and, if necessary, the unreacted polyisocyanate component).

[0088] More specifically, the amount of the organotin catalyst added (if added multiple times, the total amount) is 50 ppm or more, preferably 70 ppm or more, more preferably 90 ppm or more, even more preferably 100 ppm or more, and particularly preferably 120 ppm or more, relative to the total amount of the prepolymer composition.

[0089] When the amount of the organotin catalyst added is above the lower limit, unevenness in curing is suppressed, and as a result, a polyurethane resin having both excellent mechanical properties and excellent appearance is obtained.

[0090] The amount of the organotin catalyst added (if added multiple times, the total amount) is, for example, 5000 ppm or less, preferably 1000 ppm or less, more preferably 500 ppm or less, even more preferably 400 ppm or less, and particularly preferably 300 ppm or less, relative to the total amount of the prepolymer composition.

[0091] In the amount of organotin catalyst added, ppm refers to the number of parts by mass of organotin catalyst per 1,000,000 parts by mass of the prepolymer composition (including the isocyanate-terminated prepolymer and, if necessary, unreacted polyisocyanate components).

[0092] The urethanization catalyst may also contain a catalyst other than the organotin catalyst. Examples of catalysts other than the organotin catalyst include organometallic catalysts containing metals other than tin, amine catalysts, and potassium salts, and preferably organometallic catalysts containing metals other than tin. Examples of such organometallic catalysts include organolead catalysts, organonickel catalysts, organocopper catalysts, and organobismuth catalysts.

[0093] In the urethanization catalyst, the content of the catalyst other than the organotin catalyst is not particularly limited and is set appropriately depending on the purpose and application.

[0094] Preferably, the urethanization catalyst does not contain any catalyst other than the organotin catalyst, i.e., the urethanization catalyst preferably consists of the organotin catalyst.

[0095] The timing of adding the urethanization catalyst is not particularly limited. For example, the urethanization catalyst can be added to the polyisocyanate component and / or the polyol component in the prepolymer preparation step. Alternatively, the urethanization catalyst can be added when the polyisocyanate component and the polyol component are mixed in the prepolymer preparation step. Alternatively, the urethanization catalyst can be added to the mixture (reaction mixture) of the polyisocyanate component and the polyol component.

[0096] In the chain extension step, a urethanization catalyst can be added to the prepolymer composition and / or the chain extender, or when the prepolymer composition and the chain extender are mixed in the chain extension step.

[0097] Furthermore, a combination of these may be used, and the urethanization catalyst may be added at different times. The method for adding the urethanization catalyst is not particularly limited, and may be, for example, added all at once or in portions.

[0098] The urethanization catalyst may be added in either the prepolymer preparation step or the chain extension step. Preferably, the urethanization catalyst is not added in the prepolymer preparation step, but is added in the chain extension step.

[0099] (4) Polyurethane resin The polyurethane resin obtained by the above-mentioned method for producing a polyurethane resin has excellent mechanical properties and an excellent appearance.

[0100] In other words, in the above-mentioned polyurethane resin production method, the temperature of the isocyanate-terminated prepolymer is relatively low in the chain extension step, thereby suppressing the curing rate of the polyurethane resin surface, and the proportion of the organotin catalyst is relatively high, thereby improving the curing rate inside the polyurethane resin. In addition, the equivalent ratio (NCO / active hydrogen group) and reaction temperature in the chain extension step are adjusted within predetermined ranges.

[0101] Therefore, in the above-mentioned method for producing a polyurethane resin, unevenness in curing is suppressed, and as a result, a polyurethane resin having both excellent mechanical properties and excellent appearance is obtained.

[0102] As a result, the polyurethane resin is suitable for use in various industrial fields where both mechanical properties and appearance are required, such as polyurethane elastomers, paints, coating agents, and adhesives. Polyurethane elastomers are preferred.

[0103] Examples of polyurethane elastomers include TPU (thermoplastic polyurethane elastomer) and TSU (thermosetting polyurethane elastomer).Preferably, TSU (thermosetting polyurethane elastomer) is used as polyurethane elastomer.TSU (thermosetting polyurethane elastomer) is a cast molding product.

[0104] Since the polyurethane elastomer contains the polyurethane resin, it has excellent mechanical properties and appearance, and is therefore suitable for use in a variety of applications. Applications of polyurethane elastomers include, for example, transparent hard plastics, waterproofing materials, potting agents, inks, binders, films, sheets, bands, belts, shoe press belts, tubes, rollers, blades, speakers, sensors, outsoles, threads, 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]

[0105] 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."

[0106] 1.Raw materials <Polyisocyanate component> 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.

[0107] TDI: a mixture of 2,4- and 2,6-toluene diisocyanate isomers (2,4 / 2,6 isomer ratio 80:20, manufactured by Mitsui Chemicals, Inc., trade name: Cosmonate T-80)

[0108] <Polyol component> PTMEG-1000: Polytetramethylene ether glycol, number average molecular weight (Mn) 1000 PTMEG-2000: Polytetramethylene ether glycol, number average molecular weight (Mn) 2000 PCL-1000: Polycarbonate La Dimethicone, number average molecular weight (Mn) 1000 PCL-2000: Polycarbonate La Dimethicone, number average molecular weight (Mn) 2000

[0109] <Chain extender> 1,4-BD: 1,4-butanediol MOCA: 3,3'-dichloro-4,4'-diaminodiphenylmethane

[0110] <Urethanization catalyst> DBTDL: Dibutyltin dilaurate

[0111] 2. Prepolymer composition and polyurethane resin Examples 1 to 4 and Comparative Examples 1 to 16 (1) Prepolymer preparation process The polyisocyanate component and the polyol component were reacted at an equivalent ratio R1 shown in Tables 1 and 2 (the equivalent ratio (NCO / OH) for Examples 1 to 4 and Comparative Examples 1 to 7 and 9 to 15 was 3.5, the equivalent ratio (NCO / OH) for Comparative Example 8 was 2.1, and the equivalent ratio (NCO / OH) for Comparative Example 16 was 2.3) at 80°C for 5 hours under a nitrogen atmosphere until the isocyanate group concentration reached the value shown in Tables 1 and 2. Thereafter, the following additives were added to the reaction mixture. The amount of additive mixed relative to the total amount of the reaction mixture is shown below.

[0112] Hindered phenol antioxidant (product name Irganox 1076, manufactured by BASF) 0.5% by mass Phosphite ester antioxidant (product name JPP-100, manufactured by Johoku Chemical Industry Co., Ltd.) 0.3% by mass

[0113] As a result, a reaction mixture containing an isocyanate-terminated prepolymer was obtained as a prepolymer composition. In Tables 1 and 2, 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.

[0114] (2) Chain elongation process The prepolymer composition and the chain extender were preheated to the temperatures shown in Tables 1 and 2, respectively.

[0115] Next, dibutyltin dilaurate (DBTDL) was added to the prepolymer composition in an amount relative to the prepolymer composition as shown in Tables 1 and 2. Furthermore, the following additives were added to the prepolymer composition. The prepolymer composition was then mixed for 60 seconds.

[0116] Adekastab LA-72 (ADEKA Corporation, light resistance stabilizer) 0.3 parts by weight / polyurethane resin 100 parts by weight

[0117] Next, the prepolymer composition and chain extender were blended at the equivalent ratio R2 shown in Tables 1 and 2, mixed for 60 seconds, and degassed under reduced pressure at room temperature for 60 seconds. The mixture was then poured into a mold and cured under the curing conditions shown in Tables 1 and 2, followed by aging at 23°C for 3 weeks. This resulted in a polyurethane resin. More specifically, a cast polyurethane elastomer was obtained by the above-mentioned cast molding. In Tables 1 and 2, the equivalent ratio R2 indicates the equivalent ratio R2 (NCO / active hydrogen groups) of the isocyanate groups in the prepolymer composition to the active hydrogen groups in the chain extender. In addition, the equivalent ratio R2 in Tables 1 and 2 is (NCO / OH), but in Comparative Examples 8 and 16, it is (NCO / NH 2 ) means

[0118] In addition, Comparative Example 7 and Comparative Example 15 However, the pot life was short and the mixture hardened during casting, so no polyurethane resin was obtained.

[0119] 3. Evaluation <Polyurethane resin>

[0120] (1)A hardness The Shore A hardness of the polyurethane resin was measured in accordance with JIS K 7312 (1996).

[0121] (2) Tensile properties The tensile properties of the polyurethane resin were measured using a universal tensile testing machine (Intesco 205N) in accordance with JIS K 7312 (1996). Specifically, the polyurethane resin was cut to obtain No. 3 dumbbell 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.

[0122] (3) Rebound elasticity The impact resilience of the polyurethane resin was measured in accordance with JIS K 7311 (1995).

[0123] (4) Compression set The compression set of the polyurethane resin was measured in accordance with JIS K 7312 (1996).

[0124] (5) Abrasion resistance (Taber abrasion) The abrasion resistance of the polyurethane resin was evaluated by the following method. Specifically, the surface of the polyurethane resin was abraded using a Taber abrasion tester (manufactured by Toyo Seiki Seisakusho) with an abrasion wheel H-22 under conditions of a load of 1 kg and rotation speeds of 60 rpm and 1000 rpm, and the difference in mass before and after the test was measured. The smaller the mass, the better the abrasion resistance was evaluated.

[0125] (6) Low heat generation (loss coefficient: tanδ) The loss factor (tan δ) of the polyurethane resin was calculated as an index of low heat buildup. More specifically, the dynamic viscoelasticity spectrum of the polyurethane resin was measured using a dynamic viscoelasticity measuring device (IT Measurement & Control Co., Ltd., Model: DVA-220) under the following conditions: measurement start temperature -100°C, heating rate 5°C / min, tensile mode, gauge length 20 mm, static / dynamic stress ratio 1.8, and measurement frequency 10 Hz. The loss factor (tan δ) at 60°C was then calculated.

[0126] (7) Low-temperature softening (glass transition temperature: Tg) As an index of low-temperature softening property, the temperature at which the loss modulus becomes maximum in the dynamic viscoelastic spectrum was calculated as the glass transition temperature (Tg).

[0127] (8) Appearance The appearance of the polyurethane resin was visually observed and evaluated according to the following criteria. ◯: No cracks, fissures or peeling were observed. ×: Cracks, fissures or peeling were observed.

[0128] [Table 1]

[0129] [Table 2]

Claims

1. a prepolymer preparation step of 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 to obtain a prepolymer composition containing an isocyanate group-terminated prepolymer; a chain extension step of reacting the prepolymer composition with a chain extender to synthesize a polyurethane resin, an organotin catalyst is added in the prepolymer preparation step and / or the chain extension step; the proportion of the organotin catalyst is 50 ppm or more relative to the total amount of the prepolymer composition; In the chain extension step, the chain extender comprises a low-molecular-weight polyol having a number average molecular weight of 400 or less, the temperature of the prepolymer composition before blending the prepolymer composition with the chain extender is less than 80°C; an equivalent ratio (NCO / active hydrogen group) of the isocyanate group in the prepolymer composition to the active hydrogen group in the chain extender is 1.01 or more and 1.42 or less; a reaction temperature between the prepolymer composition and the chain extender after blending the prepolymer composition and the chain extender is 100°C or higher and 140°C or lower.

2. The method for producing a polyurethane resin according to claim 1, wherein the bis(isocyanatomethyl)cyclohexane includes 1,4-bis(isocyanatomethyl)cyclohexane.

3. The method for producing a polyurethane resin according to claim 1 or 2, wherein the bis(isocyanatomethyl)cyclohexane includes trans-1,4-bis(isocyanatomethyl)cyclohexane.

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