WO2023048033A1 - Method for producing polyurethane resin, and polyurethane resin - Google Patents

Abstract

A polyisocyanate ingredient including bis(isocyanatomethyl)cyclohexane is reacted with a polyol ingredient including a macropolyol in such a proportion that the equivalent ratio (NCO/OH) exceeds 1.0 to thereby obtain a prepolymer composition including an isocyanate-group-terminated prepolymer. The prepolymer composition is reacted with a chain extender to synthesize a polyurethane resin. Antioxidants are added in the prepolymer production step and/or the chain extension step. The antioxidants include a both-hindered phenolic antioxidant and a phosphite-based antioxidant. The proportion of the both-hindered phenolic antioxidant is 0.30-1.00 part by mass per 100 parts by mass of the prepolymer composition. The reaction between the prepolymer composition and the chain extender is conducted at a temperature of 120-140°C.

Description

Method for producing polyurethane resin, and polyurethane resin

The present invention relates to a method for producing a polyurethane resin and a polyurethane resin.

A polyurethane resin has, for example, soft segments formed by the reaction of polyisocyanate and macropolyol, and hard segments formed by the reaction of polyisocyanate and a chain extender.

More specifically, polyurethane resins obtained by the following methods are known. That is, first, 1,4-bis(isocyanatomethyl)cyclohexane and polytetramethylene ether glycol are reacted to obtain an isocyanate group-terminated prepolymer. Next, the isocyanate group-terminated prepolymer and 1,4-butanediol are each preheated to 80° C. and mixed. Further, Irganox 245 (manufactured by BASF, a heat stabilizer) is added to 0.5 phr. Then, the mixture is injected into a mold and cured at 130° C. for 4 hours to obtain a thermoplastic polyurethane resin (see, for example, Patent Document 1 (manufacturing example 1)).

JP 2020-164570 A

However, the polyurethane resin obtained by the above method may not have sufficient mechanical properties. In addition, the polyurethane resin obtained by the above method does not have sufficient discoloration resistance and crack resistance, and may not have an excellent appearance.

The present invention is a polyurethane resin production method for producing a polyurethane resin having both excellent mechanical properties and excellent appearance, and a polyurethane resin.

The present invention [1] comprises a polyisocyanate component containing bis(isocyanatomethyl)cyclohexane and a polyol component containing a macropolyol, wherein the equivalent ratio of isocyanate groups in the polyisocyanate component to hydroxyl groups in the polyol component (NCO/OH ) is reacted at a rate exceeding 1.0 to obtain a prepolymer composition containing an isocyanate group-terminated prepolymer, and the prepolymer composition is reacted with a chain extender to synthesize a polyurethane resin. and an antioxidant is added in the prepolymer preparation step and/or the chain elongation step, and the antioxidant is a hindered phenol-based compound having a structure represented by the following formula (1) It contains an antioxidant and a phosphorous acid-based antioxidant, and the proportion of the hindered phenol-based antioxidant is 0.30 parts by mass or more and 1.00 parts by mass with respect to 100 parts by mass of the prepolymer composition. and the reaction temperature between the prepolymer composition and the chain elongating agent in the chain elongating step is 120° C. or higher and 140° C. or lower.

（式中、Ｒ１およびＲ２は、同一または相異なって、炭素数３～６の１価の分岐鎖状炭化水素基を示す。）

(In the formula, R1 and R2 are the same or different and represent a monovalent branched hydrocarbon group having 3 to 6 carbon atoms.)

The present invention [2] provides the method for producing a polyurethane resin according to [1] above, wherein the hindered phenol-based antioxidant has one structure represented by the formula (1) in one molecule, contains.

The present invention [3] includes the method for producing a polyurethane resin according to [1] or [2] above, wherein the hindered phenol antioxidant has a structure represented by the following formula (2): .

（式中、Ｒ１およびＲ２は、同一または相異なって、炭素数３～６の１価の分岐鎖状炭化水素基を示す。Ｒ３は、炭素数１～６の２価の炭化水素基を示す。Ｒ４は、炭素数１～３０の１価の炭化水素基を示す。）

(In the formula, R1 and R2 are the same or different and represent a monovalent branched hydrocarbon group having 3 to 6 carbon atoms. R3 represents a divalent hydrocarbon group having 1 to 6 carbon atoms. .R4 represents a monovalent hydrocarbon group having 1 to 30 carbon atoms.)

The present invention [4] includes the method for producing a polyurethane resin according to [3] above, wherein R4 in the formula (2) represents a monovalent hydrocarbon group having 10 to 20 carbon atoms.

The present invention [5] has an elongation at break of 500% or more as measured in accordance with JIS K 7312 (1996), and a permanent compression set of 30% as measured in accordance with JIS K 7312 (1996). is less than, the Taber abrasion amount measured at a load of 1 kg, a rotation speed of 60 rpm and 1000 rotations is less than 100 mg, the b ^* value measured after ultraviolet irradiation for 400 hours is less than 5, and heated at 110 ° C. for 800 hours The elongation at break measured after heating exceeds 60% with respect to the elongation at break measured before the heating.

In the method for producing a polyurethane resin of the present invention, the antioxidant contains a hindered phenol-based antioxidant having a structure represented by the above formula (1) and a phosphite-based antioxidant. Also, the ratio of the hindered phenol-based antioxidant having the structure represented by the above formula (1) is adjusted within a predetermined range. Furthermore, the reaction temperature between the prepolymer composition and the chain extender is adjusted within a predetermined range.

Therefore, in the method for producing a polyurethane resin of the present invention, a polyurethane resin having both excellent mechanical properties and excellent appearance can be obtained.

In addition, the polyurethane resin of the present invention has both excellent mechanical properties and excellent appearance.

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 and a chain extender (described later) are reacted to produce a polyurethane resin. Each step will be described in detail below.

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

More specifically, in the prepolymer preparation step, an isocyanate group-terminated prepolymer is synthesized by reacting a polyisocyanate component and a polyol component at a predetermined ratio described later (prepolymer synthesis step).

The polyisocyanate component contains bis(isocyanatomethyl)cyclohexane as an essential component. Bis(isocyanatomethyl)cyclohexane includes, for example, 1,3-bis(isocyanatomethyl)cyclohexane and 1,4-bis(isocyanatomethyl)cyclohexane. From the viewpoint of improving the mechanical properties of the polyurethane resin, 1,4-bis(isocyanatomethyl)cyclohexane, which has a symmetrical structure, is preferred. Thus, bis(isocyanatomethyl)cyclohexane preferably contains 1,4-bis(isocyanatomethyl)cyclohexane.

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 cis-1,4-isomer. In addition, trans-1,4-bis(isocyanatomethyl)cyclohexane is sometimes referred to as trans-1,4-isomer. The total amount of trans-1,4-isomer and cis-1,4-isomer is 100 mol %.

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, still more preferably , 85 mol % or more. 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. , more preferably 90 mol % or less.

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. , 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 further Preferably, it is 15 mol % or less.

If the content of trans-1,4-isomer and the content of cis-1,4-isomer are within the above ranges, a polyurethane resin with excellent mechanical properties can be obtained.

Bis(isocyanatomethyl)cyclohexane, for example, is available as a commercial product. Moreover, bis(isocyanatomethyl)cyclohexane can be produced from bis(aminomethyl)cyclohexane by a known isocyanation method. The isocyanate-forming method includes, for example, a cold/heat two-stage phosgenation method, a salt formation method, and a non-phosgene method.

In addition, bis(isocyanatomethyl)cyclohexane may be modified as long as it does not impair the excellent effects of the present invention. Modified compounds include, for example, uretdione modified products, isocyanurate modified products, iminooxadiazinedione modified products, biuret modified products, allophanate modified products, polyol adducts, oxadiazinetrione modified products and carbodiimide modified products.

In addition, the polyisocyanate component can contain other polyisocyanates (preferably diisocyanates) as optional components within a range that does not impair the excellent effects of the present invention.

Other polyisocyanates are isocyanates other than bis(isocyanatomethyl)cyclohexane. Other polyisocyanates include, for example, aliphatic polyisocyanates, alicyclic polyisocyanates (excluding bis(isocyanatomethyl)cyclohexane), aromatic polyisocyanates, and araliphatic polyisocyanates. Examples of aliphatic polyisocyanates include pentamethylene diisocyanate (PDI) and hexamethylene diisocyanate (HDI). Alicyclic polyisocyanates include, for example, isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), and methylene bis(cyclohexyl isocyanate) (H ₁₂ MDI). Aromatic polyisocyanates include, for example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), toluidine diisocyanate (TODI), and naphthalene diisocyanate (NDI). Araliphatic polyisocyanates include, for example, xylylene diisocyanate (XDI) and tetramethylxylylene diisocyanate (TMXDI). Further, the other polyisocyanate may be the above-described modified product as long as it does not impair the excellent effects of the present invention. These can be used alone or in combination of two or more.

The content of the other polyisocyanate is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less, particularly preferably 10% by mass or less, from the viewpoint of mechanical properties with respect to the total amount of the polyisocyanate component. is 0% by mass. In addition, 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, relative to the total amount of the polyisocyanate component. % or more, particularly preferably 100% by mass. Thus, the polyisocyanate component particularly preferably consists of bis(isocyanatomethyl)cyclohexane.

The polyol component contains macropolyol as an essential component.

A macropolyol is an organic compound with a relatively high molecular weight that has two or more hydroxyl groups in its molecule. Relatively high molecular weight indicates a number average molecular weight greater than 400, preferably 500 or greater.

Examples of macropolyols include polyether polyols, polyester polyols, polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, and vinyl monomer-modified polyols. Macropolyols preferably include polyether polyols, polyester polyols and polycarbonate polyols.

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

Examples of polyester polyols include condensed polyester polyols and ring-opened polyester polyols. Examples of condensed polyester polyols include adipate-based polyester polyols and phthalic acid-based polyester polyols. Ring-opened polyester polyols include, for example, lactone-based polyester polyols, more specifically polycaproctone polyols.

Polycarbonate polyols include, for example, ring-opening polymers of ethylene carbonate using a low-molecular-weight polyol, which will be described later, as an initiator.

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

As the macropolyol, polyether polyol is more preferable, and polytetramethylene ether polyol is more preferable.

The number average molecular weight of the macropolyol exceeds 400, preferably 500 or more, more preferably 650 or more, and still more preferably 1000 or more. Also, the number average molecular weight of the macropolyol is, for example, 5000 or less, preferably 3000 or less, more preferably 2000 or less. Moreover, 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 still more preferably 2.5 or less. Also, the average number of functional groups (average number of hydroxyl groups) of the macropolyol is most preferably two.

The polyol component can contain a low-molecular-weight polyol as an optional component.

A low-molecular-weight polyol is a relatively low-molecular-weight organic compound that has two or more hydroxyl groups in its molecule. A relatively low molecular weight indicates a number average molecular weight of 400 or less, preferably 300 or less. That is, the molecular weight of the low-molecular-weight polyol is, for example, 400 or less, preferably 300 or less. Moreover, the molecular weight of the low-molecular-weight polyol is usually 40 or more.

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

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, relative to the total amount of the polyol component. In addition, the content of the macropolyol 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 with respect to the total amount of the polyol component. . That is, the polyol component particularly preferably consists of macropolyols.

The mixing ratio of the polyisocyanate component and the polyol component is adjusted so that the isocyanate groups in the polyisocyanate component are excessive relative to the hydroxyl groups in the polyol component.

More specifically, in the prepolymer synthesis step, the equivalent ratio R1 (NCO/OH) of isocyanate groups in the polyisocyanate component to hydroxyl groups in the polyol component exceeds 1.0, preferably 1.1. 1.3 or more, more preferably 1.3 or more. Also, 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.

In the prepolymer synthesis step, reaction methods include, for example, bulk polymerization and solution polymerization.

In bulk polymerization, for example, a polyisocyanate component and a polyol component are reacted under a nitrogen stream. The reaction temperature is, for example, 50° C. or higher. Also, the reaction temperature is, for example, 250° C. or lower, preferably 200° C. or lower. Also, the reaction time is, for example, 0.5 hours or longer, preferably 1 hour or longer. Also, the reaction time is, for example, 15 hours or less.

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

In the prepolymer synthesis step, for example, the above reaction is carried out until the isocyanate group concentration (NCO%) of the reaction product liquid (prepolymer composition) reaches a predetermined value (described later).

In addition, a known urethanization catalyst may be added in the prepolymer synthesis step. Urethane catalysts include, for example, organometallic catalysts, amine catalysts and potassium salts. These can be used alone or in combination of two or more. As the urethanization catalyst, an organometallic catalyst is preferably used.

Examples of organometallic catalysts include organotin catalysts, organolead catalysts, organonickel catalysts, organocopper catalysts and organobismuth catalysts. These can be used alone or in combination of two or more. The organometallic catalyst preferably includes an organotin catalyst.

Examples of organotin catalysts include tin acetate, tin octylate, tin oleate, tin laurate, monobutyltin trioctate, dibutyltin diacetate, dimethyltin dilaurate, dibutyltin dilaurate, dibutyltin dimercaptide, dibutyltin maleate, and dibutyltin. Dineodecanoate, dioctyltin dimercaptide, dioctyltin dilaurate, and dibutyltin dichloride. These can be used alone or in combination of two or more. The organotin catalyst preferably includes dibutyltin dilaurate.

The amount of the urethanization catalyst to be added is not particularly limited, and is appropriately set according to the purpose and application. Moreover, the timing of adding the urethanization catalyst is not particularly limited. For example, a urethanization catalyst can be added to the polyisocyanate component and/or the polyol component in the prepolymer synthesis step. Further, in the prepolymer synthesis step, a urethanization catalyst can be added during mixing of the polyisocyanate component and the polyol component. Also, a urethanization catalyst can be added to the mixture (reaction mixture) of the polyisocyanate component and the polyol component.

Alternatively, a plurality of these may be combined to add the urethanization catalyst at a plurality of timings. Moreover, the method of adding the urethanization catalyst is not particularly limited, and for example, it may be added all at once or may be added in portions.

As a result, a reaction product liquid between the polyisocyanate component and the polyol component is obtained.

The reaction product liquid contains, for example, an isocyanate group-terminated prepolymer that is a reaction product of a polyisocyanate component and a polyol component, and a polyisocyanate component that is an unreacted raw material.

In the reaction product liquid, 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.

If necessary, part of the unreacted polyisocyanate component (unreacted raw material) can be removed from the reaction product liquid by a known method.

Then, in the prepolymer preparation step, the reaction product liquid (the reaction product liquid in the prepolymer synthesis step) can be obtained as a prepolymer composition.

In addition, in the prepolymer preparation step, for example, an isocyanate monomer can be further added to the reaction product liquid in the prepolymer synthesis step (monomer addition step).

Examples of isocyanate monomers include the above-mentioned bis(isocyanatomethyl)cyclohexane and other polyisocyanates. These can be used alone or in combination of two or more. The isocyanate monomer preferably includes the same polyisocyanate as the polyisocyanate component used in the prepolymer synthesis step. More specifically, the isocyanate monomer preferably includes bis(isocyanatomethyl)cyclohexane.

The addition ratio of the isocyanate monomer to the reaction product liquid in the prepolymer synthesis step is appropriately set according to the purpose and application.

For example, the equivalent of the total amount of the isocyanate groups of the polyisocyanate component used in the prepolymer synthesis step and the isocyanate groups of the isocyanate monomers used in the monomer addition step to the hydroxyl groups in the polyol component used in the prepolymer synthesis step The ratio R2 (NCO/OH) is, for example, 3.0 or more, preferably 4.0 or more.

Also, the equivalent of the total amount of the isocyanate groups of the polyisocyanate component used in the prepolymer synthesis step and the isocyanate groups of the isocyanate monomer used in the monomer addition step with respect to the hydroxyl groups in the polyol component used in the prepolymer synthesis step The ratio R2 (NCO/OH) is, for example, 10.0 or less, preferably 6.0 or less, more preferably 5.5 or less.

Thereby, in the prepolymer preparation step, a mixture of the reaction product liquid of the prepolymer synthesis step and the isocyanate monomer can be obtained as a prepolymer composition.

The isocyanate group concentration of the prepolymer composition is, for example, 1% by mass or more, preferably 5% by mass or more, and more preferably 15% by mass or more. Also, the isocyanate group concentration of the prepolymer composition is, for example, 30% by mass or less, preferably 25% by mass or less, and more preferably 20% by mass or less. The isocyanate group concentration (isocyanate group content) can be obtained by a known measuring method. Measurement methods include, for example, titration with di-n-butylamine and FT-IR analysis (same below).

Although details will be described later, an antioxidant may be added in the prepolymer preparation step.

(3) Chain elongation step Next, in this method, the prepolymer composition and a chain elongation agent are reacted to synthesize a polyurethane resin (chain elongation step).

A chain extender is a curing agent for the prepolymer composition. Examples of chain extenders include low-molecular-weight compounds containing a plurality (preferably two) of active hydrogen groups (hydroxyl group, amino group). Low molecular weight compounds more specifically include low molecular weight polyols and low molecular weight polyamines. Chain extenders preferably include low molecular weight polyols. A polyurethane resin having excellent mechanical properties can be obtained by using a low-molecular-weight polyol.

Low-molecular-weight polyols include the above-mentioned low-molecular-weight polyols. More specifically, low molecular weight polyols include, for example, the above dihydric alcohols, the above trihydric alcohols, and the above tetrahydric or higher alcohols. These can be used alone or in combination of two or more.

The low-molecular-weight polyol preferably includes dihydric alcohols and trihydric alcohols, more preferably dihydric alcohols, and still more preferably 1,4-butanediol. That is, the low molecular weight polyol preferably comprises 1,4-butanediol, more preferably consists of 1,4-butanediol. Thereby, a polyurethane resin having excellent mechanical properties can be obtained.

The mixing ratio of the prepolymer composition and the chain extender is such that the equivalent ratio R3 (NCO/active hydrogen group) of the isocyanate group in the prepolymer composition to the active hydrogen group in the chain extender is, for example, 0.85. Above, it is preferably 0.90 or more, more preferably 0.95 or more, still more preferably 1.00 or more, and most preferably 1.05 or more. In addition, the equivalent ratio R3 (NCO/active hydrogen group) of the isocyanate group in the prepolymer composition to the active hydrogen group in the chain extender is, for example, 1.40 or less, preferably 1.30 or less, more preferably is 1.20 or less, more preferably 1.10 or less.

Also, preferably, in the chain elongation step, the temperature of the prepolymer composition is adjusted by heating (preheating) before blending the prepolymer composition and the chain elongating agent. In the chain elongation step, the temperature of the prepolymer composition is, for example, less than 80°C, preferably 75°C or less, more preferably 70°C or less. Also, the temperature of the prepolymer composition is, for example, 30° C. or higher, preferably 40° C. or higher, more preferably 50° C. or higher.

Also, preferably, in the chain elongation step, the temperature of the chain elongation agent is also adjusted by heating (preheating) before blending the prepolymer composition and the chain elongation agent. In the chain elongation step, the temperature of the chain elongation agent is preferably lower than the temperature of the prepolymer composition. More specifically, 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 higher, preferably 30°C or higher, more preferably 35°C or higher.

Then, in the chain elongation step, for example, the prepolymer composition and the chain elongation agent are mixed in the above ratio and heated. This yields a polyurethane resin comprising the reaction product of the prepolymer composition and the chain extender.

The reaction temperature (curing temperature) in the chain elongation step is 120°C or higher, preferably 125°C or higher, more preferably 130°C or higher. In addition, the reaction temperature (curing temperature) in the chain elongation step is 140° C. or lower, preferably 138° C. or lower, more preferably 135° C. or lower.

If the reaction temperature in the chain elongation step is above the above lower limit, excellent mechanical properties (particularly abrasion resistance) can be obtained. Also, if the reaction temperature in the chain elongation step is below the above upper limit, an excellent pot life can be obtained.

The reaction time (curing time) in the chain elongation step is, for example, 1 hour or longer, preferably 2 hours or longer. The reaction time (curing time) in the chain elongation step is, for example, 24 hours or less, preferably 12 hours or less, more preferably 6 hours or less.

If the reaction time in the chain elongation step is within the above range, a polyurethane resin having both excellent mechanical properties and excellent appearance can be obtained.

In addition, the above-described urethanization catalyst may be added in the chain elongation step.

The amount of the urethanization catalyst to be added is not particularly limited, and is appropriately set according to the purpose and application. Moreover, the timing of adding the urethanization catalyst is not particularly limited. For example, a urethanization catalyst can be added to the prepolymer composition and/or the chain extender in the chain extension step. Also, in the chain elongation step, a urethanization catalyst can be added during mixing of the prepolymer composition and the chain elongation agent.

Alternatively, a plurality of these may be combined to add the urethanization catalyst at a plurality of timings. Moreover, the method of adding the urethanization catalyst is not particularly limited, and for example, it may be added all at once or may be added in portions.

Although details will be described later, an antioxidant may be added in the chain elongation step.

Further, when the polyurethane resin is a polyurethane elastomer, in the chain elongation step, the mixture of the prepolymer composition and the chain elongation agent is preferably defoamed as necessary and heat-cured in a preheated mold. and removed from the mold. As a result, a cast polyurethane elastomer molded into a desired shape is obtained as a polyurethane resin.

Also, in this method, the polyurethane resin can be heat-treated, if necessary. The heat treatment temperature is, for example, 50° C. or higher, preferably 80° C. or higher. Also, the heat treatment temperature is, for example, 200° C. or lower, preferably 150° C. or lower. Also, the heat treatment time is, for example, 30 minutes or longer, preferably 1 hour or longer. Also, the heat treatment time is, for example, 30 hours or less, preferably 20 hours or less.

In addition, polyurethane resin can be cured. The curing temperature is, for example, 10°C or higher, preferably 20°C or higher. Also, the curing temperature is, for example, 50° C. or lower, preferably 40° C. or lower. Also, the curing time is, for example, 1 hour or longer, preferably 10 hours or longer. Also, the curing time is, for example, 50 days or less, preferably 30 days or less.

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

(3) Antioxidant In the method for producing a polyurethane resin described above, an antioxidant is added in one or both of the prepolymer preparation step and the chain elongation step.

The antioxidant contains, as essential components, a hindered phenol-based antioxidant having a structure represented by the following formula (1) and a phosphite-based antioxidant.

（式中、Ｒ１およびＲ２は、同一または相異なって、炭素数３～６の１価の分岐鎖状炭化水素基を示す。）

(In the formula, R1 and R2 are the same or different and represent a monovalent branched hydrocarbon group having 3 to 6 carbon atoms.)

In the structure shown in formula (1) above, both of the two ortho-positions to the hydroxyl group of the phenol skeleton are substituted with monovalent branched hydrocarbon groups having 3 to 6 carbon atoms.

In the following, the structure represented by the above formula (1) may be referred to as a double hindered phenol structure. Moreover, the hindered phenol-based antioxidant having the structure represented by the above formula (1) may be referred to as both hindered phenol-based antioxidants.

In the structure shown in formula (1) above, R1 and R2 are the same or different and represent a monovalent branched hydrocarbon group having 3 to 6 carbon atoms. Examples of C 3-6 monovalent branched hydrocarbon groups include isopropyl, isobutyl, s-butyl, t-butyl and neopentyl.

The monovalent branched hydrocarbon group having 3 to 6 carbon atoms represented by R1 and R2 is preferably t-butyl from the viewpoint of mechanical properties and appearance.

The monovalent branched hydrocarbon groups having 3 to 6 carbon atoms represented by R1 and R2 may be different from each other, but are preferably the same. More preferably both R1 and R2 denote t-butyl.

In both hindered phenol-based antioxidants, the number of structures represented by the above formula (1) is not particularly limited. That is, one molecule of both hindered phenol-based antioxidants may have one structure represented by the above formula (1), or may have two or more structures.

In both hindered phenol-based antioxidants, the number of structures represented by the above formula (1) (the number of both hindered phenol structures) is preferably 4 or less, more preferably 3, from the viewpoint of mechanical properties and appearance. 2 or less, more preferably 1 or less.

That is, both hindered phenol-based antioxidants particularly preferably have one structure represented by the above formula (1) in one molecule. Such both hindered phenolic antioxidants preferably have a structure represented by the following formula (2).

（式中、Ｒ１およびＲ２は、同一または相異なって、炭素数３～６の１価の分岐鎖状炭化水素基を示す。Ｒ３は、炭素数１～６の２価の炭化水素基を示す。Ｒ４は、炭素数１～３０の１価の炭化水素基を示す。）

(In the formula, R1 and R2 are the same or different and represent a monovalent branched hydrocarbon group having 3 to 6 carbon atoms. R3 represents a divalent hydrocarbon group having 1 to 6 carbon atoms. .R4 represents a monovalent hydrocarbon group having 1 to 30 carbon atoms.)

In formula (2) above, R1 and R2 have the same meanings as R1 and R2 in formula (1) above.

In the above formula (2), R3 represents a divalent hydrocarbon group having 1 to 6 carbon atoms. Examples of the divalent hydrocarbon group having 1 to 6 carbon atoms include a linear divalent hydrocarbon group having 1 to 6 carbon atoms and a branched divalent hydrocarbon group having 3 to 6 carbon atoms. is mentioned. Examples of divalent hydrocarbon groups having 1 to 6 carbon atoms include methylene, ethylene, trimethylene, tetramethylene, pentamethylene and hexamethylene. Examples of the divalent branched hydrocarbon group having 3 to 6 carbon atoms include propylene (1,2-propylene).

The divalent hydrocarbon group having 1 to 6 carbon atoms represented by R3 is preferably a linear divalent hydrocarbon group having 1 to 6 carbon atoms, more preferably, from the viewpoint of mechanical properties and appearance. includes a divalent linear hydrocarbon group having 2 to 4 carbon atoms, more preferably ethylene.

In the above formula (2), R4 represents a monovalent hydrocarbon group having 1 to 30 carbon atoms. Examples of monovalent hydrocarbon groups having 1 to 30 carbon atoms include monovalent linear hydrocarbon groups having 1 to 30 carbon atoms and monovalent branched hydrocarbon groups having 3 to 30 carbon atoms. is mentioned. Examples of monovalent linear hydrocarbon groups having 1 to 30 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, and pentadecyl. , hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl and triacontyl. Examples of monovalent branched hydrocarbon groups having 3 to 30 carbon atoms include isopropyl, isobutyl, s-butyl, t-butyl, isopentyl, neopentyl, 2-ethylhexyl and 3,3,5-trimethylhexyl. , isooctyl, isononyl, 2-hexyldecyl and isodecyl.

The monovalent hydrocarbon group having 1 to 30 carbon atoms represented by R4 preferably includes a monovalent hydrocarbon group having 10 to 20 carbon atoms, more preferably carbon, from the viewpoint of mechanical properties and appearance. Examples include monovalent linear hydrocarbon groups of number 10 to 20, more preferably octadecyl.

More specifically, the double-hindered phenol-based antioxidant includes an antioxidant having one double-hindered phenol structure, and an antioxidant having a plurality of (two or more) double-hindered phenol structures. .

Antioxidants having one structure of both hindered phenols include, for example, antioxidants having a structure represented by the above formula (2), more specifically, for example, 3-(4-hydroxy- octyl 3,5-diisopropylphenyl)propionate and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

Antioxidants having one double hindered phenol structure also include antioxidants that do not have the structure represented by the above formula (2). Antioxidants not having the structure represented by formula (2) include, for example, dibutylhydroxytoluene (BHT).

Antioxidants having a plurality of double hindered phenol structures include, for example, an antioxidant having two double hindered phenol structures, an antioxidant having three double hindered phenol structures, and an antioxidant having double hindered phenol structures. Antioxidants having four are mentioned.

Antioxidants having two hindered phenol structures include, for example, bis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionic acid]thiobisethylene. Antioxidants having three hindered phenol structures include, for example, 1,3,5-tris(3,5-di-t-butyl-4-hydroxyphenylmethyl)-2,4,6-trimethylbenzene is mentioned. Antioxidants having four hindered phenol structures include, for example, bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]2,2-bis[[[3- (3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]oxy]methyl]propane-1,3-diyl.

Both hindered phenol-based antioxidants can be used alone or in combination of two or more.

The double-hindered phenol-based antioxidant preferably includes an antioxidant having one double-hindered phenol structure and an antioxidant having two double-hindered phenol structures, more preferably double-hindered phenol-based antioxidants. Antioxidants having one dophenol structure, more preferably antioxidants having a structure represented by the above formula (2), more preferably 3-(4-hydroxy-3,5 -diisopropylphenyl)octyl propionate and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)octadecyl propionate, particularly preferably 3-(3,5-di-tert- Octadecyl butyl-4-hydroxyphenyl)propionate.

Both hindered phenolic antioxidants are commercially available. Commercial products of both hindered phenol-based antioxidants include, for example, Irganox 1135 (both hindered phenol structure number 1, manufactured by BASF), Irganox 1076 (both hindered phenol structure number 1, manufactured by BASF), Irganox 1035 (both hindered phenol 2 structures, manufactured by BASF), Adekastab AO-330 (3 structures of both hindered phenols, manufactured by ADEKA), and Irganox 1010 (4 structures of both hindered phenols, manufactured by BASF).

As commercial products of both hindered phenol-based antioxidants, preferably Irganox 1135 (both hindered phenol structure number 1, manufactured by BASF), Irganox 1076 (both hindered phenol structure number 1, manufactured by BASF) and Irganox 1035 (both hindered phenol Structure number 2, manufactured by BASF), more preferably Irganox 1135 (both hindered phenol structure number 1, manufactured by BASF) and Irganox 1076 (both hindered phenol structure number 1, manufactured by BASF), more preferably Irganox 1076 (both hindered phenol structures: 1, manufactured by BASF).

The blending ratio of both hindered phenol-based antioxidants is 0.30 parts by mass or more, preferably 0.40 parts by mass or more, more preferably 0.45 parts by mass with respect to 100 parts by mass of the prepolymer composition. That's it. The blending ratio of both hindered phenol-based antioxidants is 1.00 parts by mass or less, preferably 0.80 parts by mass or less, more preferably 0.60 parts by mass, based on 100 parts by mass of the prepolymer composition. Part by mass or less.

If the blending ratio of both hindered phenol-based antioxidants exceeds the above lower limit, excellent heat resistance and light resistance can be obtained, and deterioration of appearance can be suppressed. Further, if the blending ratio of both hindered phenol-based antioxidants is below the above upper limit, the decrease in hardness and modulus can be suppressed.

If the blending ratio of both hindered phenol-based antioxidants is within the above range, a polyurethane resin having both excellent mechanical properties and excellent appearance can be obtained.

Also, a double-hindered phenol-based antioxidant and a single-hindered phenol-based antioxidant can be used in combination. That is, the antioxidant can contain a single hindered phenolic antioxidant as an optional component.

A hindered phenol-based antioxidant is, for example, a hindered phenol-based antioxidant that does not have the structure represented by the above formula (1) but has the structure represented by the following formula (3).

（式中、Ｒ１は、炭素数３～６の１価の分岐鎖状炭化水素基を示す。Ｒ５は、水素原子、または、炭素数１～６の１価の直鎖状炭化水素基を示す。）

(In the formula, R1 represents a monovalent branched hydrocarbon group having 3 to 6 carbon atoms.R5 represents a hydrogen atom or a monovalent linear hydrocarbon group having 1 to 6 carbon atoms. .)

In the above formula (3), R1 has the same meaning as R1 in the above formula (1).

In the above formula (3), R5 represents a monovalent linear hydrocarbon group having 1 to 6 carbon atoms. Examples of C 1-6 monovalent linear hydrocarbon groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl and n-hexyl.

In the one-sided hindered phenol-based antioxidant, the number of structures represented by the above formula (3) is not particularly limited. That is, one molecule of the single-hindered phenol-based antioxidant may have one structure represented by the above formula (3), or may have two or more structures.

Examples of single hindered phenolic antioxidants include 3,6-dioxaoctane-1,8-diolbis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate]. .

Single hindered phenolic antioxidants are commercially available. Commercially available products of the single hindered phenolic antioxidant include, for example, Irganox 245 (manufactured by BASF).

The blending ratio of the one-sided hindered phenolic antioxidant is not particularly limited, and is appropriately set according to the purpose and application. Preferably, the antioxidant does not include mono-hindered phenolic antioxidants.

That is, the antioxidant preferably consists of a hindered phenol-based antioxidant and a phosphorous acid-based antioxidant.

Examples of phosphite-based antioxidants include aliphatic phosphites, alicyclic phosphites, and aromatic phosphites. Examples of aliphatic phosphites include triethylphosphite, tributylphosphite, tris(2-ethylhexyl)phosphite, tridecylphosphite, trilaurylphosphite, tris(tridecyl)phosphite, tristearylphosphite, Distearyl pentaerythrityl diphosphite, didodecyl pentaerythritol diphosphite, ditridecyl pentaerythritol diphosphite, and tripentaerythritol triphosphite. Alicyclic phosphites include, for example, hydrogenated bisphenol A phosphite polymers. Examples of aromatic phosphites include triphenylphosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, diphenyldecylphosphite, diphenyl(tridecyl)phosphite, phyto, dinonylphenylpentaerythritol diphosphite, tetraphenyltetratridecylpentaerythrityl tetraphosphite, tetraphenyldipropylene glycol diphosphite, and 4,4′-butylidene-bis(3-methyl-6-t -butylphenyl-ditridecyl)phosphite. These can be used alone or in combination of two or more. Phosphite-based antioxidants preferably include aromatic phosphites, and more preferably include tetraphenyldipropylene glycol diphosphite.

Phosphite-based antioxidants are commercially available. Commercially available phosphorous acid antioxidants include, for example, JPP-100 (manufactured by Johoku Kagaku Kogyo Co., Ltd.).

The mixing ratio of the phosphite-based antioxidant is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, more preferably 0.10 parts by mass with respect to 100 parts by mass of the prepolymer composition. Department or above. Further, the phosphite-based antioxidant is, for example, 1.00 parts by mass or less, preferably 0.70 parts by mass or less, more preferably 0.50 parts by mass with respect to 100 parts by mass of the prepolymer composition. It is below.

In addition, the blending ratio of the phosphite-based antioxidant is less than the blending ratio of both hindered phenol-based antioxidants. The mixing ratio of the phosphite-based antioxidant is, on a mass basis, for example, 0.9 times or less, preferably 0.7 times or less, more preferably 0.7 times or less, with respect to the mixing ratio of both hindered phenol-based antioxidants. is 0.5 times or less. In addition, the mixing ratio of the phosphite-based antioxidant is, on a mass basis, for example, 0.1 times or more, preferably 0.2 times or more, with respect to the mixing ratio of both hindered phenol-based antioxidants. be.

The timing of adding the antioxidant is not particularly limited. For example, antioxidants can be added to the polyisocyanate component and/or the polyol component during the prepolymer preparation process. Also, in the prepolymer preparation step, an antioxidant can be added when the polyisocyanate component and the polyol component are mixed. Also, an antioxidant can be added to the mixture (reaction mixture) of the polyisocyanate component and the polyol component.

Also, in the chain elongation step, an antioxidant can be added to the prepolymer composition and/or the chain elongation agent. Also, in the chain elongation step, an antioxidant can be added during mixing of the prepolymer composition and the chain elongator.

Also, a plurality of these may be combined to add the antioxidant at a plurality of timings. Moreover, the method of adding the antioxidant is not particularly limited, and for example, it may be added all at once or may be added in portions.

Also, the timing of adding the hindered phenol-based antioxidant and the timing of adding the phosphorous acid-based antioxidant may be the same or different. Preferably, the hindered phenol antioxidant and the phosphite antioxidant are added at the same time.

Further, the antioxidant may be added to either the prepolymer preparation step or the chain elongation step. Preferably, the antioxidant is not added in the chain elongation step, and the antioxidant is added in the prepolymer preparation step. agent is added.

Furthermore, the polyurethane resin can contain known additives in addition to antioxidants, if necessary. Examples of additives include heat stabilizers, light stabilizers, ultraviolet absorbers, antiblocking agents, release agents, pigments, dyes, lubricants, fillers, hydrolysis inhibitors, rust inhibitors and bluing agents. .

Additives preferably include light stabilizers. Light stabilizers such as hindered amine light stabilizers such as tetrakis(1,2,2,6,6,-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate , tetrakis(2,2,6,6,-tetramethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, and bis(1,2,2,6,6-pentamethyl-4 - piperidyl) sebacate. These can be used alone or in combination of two or more.

The amount of additive added is appropriately set according to the purpose and application.

Also, the timing of adding the additive is not particularly limited. For example, additives can be added to the polyisocyanate component and/or the polyol component during the prepolymer preparation process. In addition, additives can be added during the mixing of the polyisocyanate component and the polyol component in the prepolymer preparation step. Additives can also be added to the mixture (reaction mixture) of the polyisocyanate component and the polyol component.

Additives can also be added to the prepolymer composition and/or the chain elongation agent in the chain elongation step. Also, in the chain elongation step, additives can be added at the time of mixing the prepolymer composition and the chain elongation agent.

(4) Polyurethane resin The polyurethane resin obtained by the method for producing a polyurethane resin described above has both excellent mechanical properties and an excellent appearance.

That is, in the method for producing a polyurethane resin described above, the antioxidant contains a hindered phenol-based antioxidant having a structure represented by the above formula (1) and a phosphite-based antioxidant. Also, the ratio of the hindered phenol-based antioxidant having the structure represented by the above formula (1) is adjusted within a predetermined range. Furthermore, the reaction temperature between the prepolymer composition and the chain extender is adjusted within a predetermined range.

Therefore, the polyurethane resin production method described above yields a polyurethane resin that has both excellent mechanical properties and an excellent appearance.

In addition, the above polyurethane resin has both excellent mechanical properties (elongation properties, compression set, and wear resistance) and excellent appearance (yellowing resistance and crack resistance).

More specifically, the Shore A hardness of the polyurethane resin is, for example, 97A or higher, preferably 98A or higher. The Shore A hardness of the polyurethane resin is, for example, 100A or less, preferably 99A or less. Note that the Shore A hardness is measured according to JIS K 7312 (1996) as described later as an example.

Also, the Shore D hardness of the polyurethane resin is, for example, 52D or more, preferably 53D or more. The Shore D hardness of the polyurethane resin is, for example, 60D or less, preferably 58D or less. Note that the Shore D hardness is measured according to JISK 7312 (1996), as described later as an example.

Also, the 100% modulus of the polyurethane resin is, for example, 8 MPa or more, preferably 18 MPa or more. Moreover, the 100% modulus of the polyurethane resin is, for example, 30 MPa or less, preferably 25 MPa or less. The 100% modulus is measured according to JIS K 7312 (1996), as described later as an example.

Also, the 300% modulus of the polyurethane resin is, for example, 10 MPa or more, preferably 25 MPa or more. Moreover, the 300% modulus of the polyurethane resin is, for example, 40 MPa or less, preferably 30 MPa or less. The 300% modulus is measured according to JIS K 7312 (1996), as described later as an example.

Also, the tensile strength of the polyurethane resin is, for example, 45 MPa or more, preferably 50 MPa or more. Further, the tensile strength of the polyurethane resin is, for example, 70 MPa or less, preferably 60 MPa or less. Incidentally, the tensile strength is measured according to JIS K 7312 (1996) as described later as an example.

Further, the elongation at break of the polyurethane resin is, for example, 500% or more, preferably 550% or more. Further, the elongation at break of the polyurethane resin is, for example, 1000% or less, preferably 800% or less. In addition, the elongation at break is JIS K as described later as an example.
7312 (1996).

Also, the compression set of the polyurethane resin is, for example, 15% or more, preferably 20% or more. Moreover, the compression set of the polyurethane resin is, for example, less than 30%, preferably 25% or less. The compression set is measured according to JIS K 7312 (1996), as described later as an example.

Also, the Taber abrasion amount of the polyurethane resin (the Taber abrasion amount measured at a load of 1 kg, a rotation speed of 60 rpm and 1000 rotations) is, for example, 0 mg or more, preferably 1 mg or more. Also, the Taber abrasion amount of the polyurethane resin (the Taber abrasion amount measured at a load of 1 kg, a rotational speed of 60 rpm and 1000 rpm) is, for example, less than 100 mg, preferably 80 mg or less. The amount of Taber wear is measured by the method described later as an example.

Further, the discoloration resistance of polyurethane resin is evaluated, for example, by the yellowness (b ^* value) of the polyurethane resin after ultraviolet irradiation.

For example, the b ^* value measured after UV irradiation for 400 hours is, for example, less than 5, preferably less than 3, and more preferably less than 1. The b ^* value measured after 400 hours of ultraviolet irradiation is, for example, −10 or more, preferably −5 or more. The b ^* value is measured by the method described later as an example.

In addition, the crack resistance of a polyurethane resin is evaluated, for example, by the retention rate of elongation at break before and after a heat resistance test.

For example, the breaking elongation measured after heating at 110° C. for 800 hours is, for example, more than 60%, preferably 80% or more, relative to the breaking elongation measured before the heating.
Also, the breaking elongation measured after heating at 110° C. for 800 hours is, for example, 100% or less, preferably 98% or less of the breaking elongation measured before the heating.
The retention rate of elongation at break is measured by the method described later as an example.

As a result, the above polyurethane resin is suitable for use in various industrial fields that require both mechanical properties and appearance. Such industrial fields include, for example, polyurethane elastomers, paints, coatings and adhesives. Polyurethane elastomers are preferred.

Examples of polyurethane elastomers include TPU (thermoplastic polyurethane elastomer) and TSU (thermosetting polyurethane elastomer). Polyurethane elastomers preferably include TSU (thermosetting polyurethane elastomer). TSU (Thermoset Polyurethane Elastomer) is a cast molded product.

Because the polyurethane elastomer contains the above polyurethane resin, it has excellent mechanical properties and appearance. Therefore, polyurethane elastomers are suitably used in various applications. Applications of polyurethane elastomers include, for example, transparent hard plastics, waterproof materials, potting agents, inks, binders, films, sheets, bands, belts, shoe press belts, tubes, rollers, blades, speakers, sensors, outsoles, threads. , textiles, non-woven fabrics, cosmetics, shoes, heat insulating materials, sealing materials, tape materials, sealing materials, solar power generation components, robot components, android components, wearable components, clothing products, sanitary products, cosmetic products, furniture products, food products Packaging materials, sporting goods, leisure goods, medical supplies, nursing care products, housing materials, acoustic materials, lighting materials, anti-vibration materials, sound-insulating materials, daily necessities, miscellaneous goods, cushions, bedding, stress-absorbing materials, stress-relieving materials, automobile interiors materials, automobile exterior materials, railway components, aircraft components, optical components, OA equipment components, miscellaneous goods surface protection components, semiconductor sealing materials, self-healing materials, health appliances, eyeglass lenses, toys, packing, cable sheaths, wire harnesses, Telecommunications cables, automotive wiring, computer wiring, industrial products, shock absorbers, semiconductor products and bridge bearings.

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

1. Raw material <Polyisocyanate component>
Production Example 1 1,4-bis(isocyanatomethyl)cyclohexane 1,4-bis(isocyanatomethyl)cyclohexane (1,4-H ₆ XDI) was obtained. The purity of 1,4-H ₆ XDI was measured by gas chromatography and found to be 99.9%. Also, the hue was 5 by APHA measurement. Further, the ratio of trans-isomer to cis-isomer measured by ¹³ C-NMR measurement was 86 mol% of trans-isomer and 14 mol% of cis-isomer.

TDI: tolylene diisocyanate PPDI: 1,4-phenylene diisocyanate

<Polyol component>
・PTMEG-1000: polytetramethylene ether glycol, number average molecular weight (Mn) 1000
・PTMEG-2000: polytetramethylene ether glycol, number average molecular weight (Mn) 2000

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

<Urethane catalyst>
・DBTDL: dibutyltin dilaurate

<Double Hindered Phenolic Antioxidant>
· Irganox 1076: 3-(3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propionate, antioxidant represented by the above formula (2), both hindered phenol structures number 1, manufactured by BASF · Irganox 1010: Bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]2,2-bis[[[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl ] Oxy]methyl]propane-1,3-diyl, both hindered phenol structures 4, manufactured by BASF Irganox 1035: bis [3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionic acid] Thiobisethylene, both hindered phenol structure number 2, manufactured by BASF Irganox 1135: 3-(4-hydroxy-3,5-diisopropylphenyl) octyl propionate, antioxidant represented by the above formula (2), both hindered 1 phenolic structure, manufactured by BASF

<Single Hindered Phenolic Antioxidant>
・Irganox 245: 3,6-dioxaoctane-1,8-diolbis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], manufactured by BASF

<Phosphite-based antioxidant>
・ JPP-100: Tetraphenyl dipropylene glycol diphosphite, Johoku Chemical Industry Co., Ltd.

<Hindered amine light stabilizer>
・ ADEKA STAB LA-72: bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, manufactured by ADEKA

2. Prepolymer Compositions and Polyurethane Resins Examples 1-10 and Comparative Examples 1-8
(1) Prepolymer preparation process Prepolymer synthesis process The polyisocyanate components and polyol components listed in Tables 1 to 4 were mixed under a nitrogen atmosphere, and the isocyanate group concentration (isocyanate group concentration after the prepolymer synthesis step) was adjusted to Table 1 to The reaction was allowed to reach the values listed in Table 4.

The equivalent ratio R1 (NCO/OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component is shown in the table.

Monomer Addition Step To the reaction product liquid in the prepolymer synthesis step, the same isocyanate monomer as the polyisocyanate component used in the prepolymer synthesis step was added.

As a result, a mixture of the reaction product liquid containing the isocyanate group-terminated prepolymer and the isocyanate monomer was obtained as a prepolymer composition.

The equivalent of the total amount of the isocyanate groups of the polyisocyanate component used in the prepolymer synthesis step and the isocyanate groups of the isocyanate monomers used in the monomer addition step with respect to the hydroxyl groups in the polyol component used in the prepolymer synthesis step The ratio R2 (NCO/OH) is given in the table. Also, the isocyanate group concentration of the prepolymer composition (isocyanate group concentration after the monomer addition step) is shown in the table.

Furthermore, an antioxidant was added to the prepolymer composition according to the formulations shown in Tables 1 to 4.

(3) Chain elongation step With respect to 100 parts by mass of the prepolymer composition, 0.03 parts by mass of dibutyltin dilaurate (urethanization catalyst, DBTDL) is added, and if necessary, In the formulation, a light stabilizer was added and the prepolymer composition was preheated to 60°C and the chain extender was preheated to 40°C.

Then, the prepolymer composition and the chain extender were blended at the equivalent ratio R3 shown in Tables 1 to 4, mixed for 60 seconds, and degassed under reduced pressure at room temperature for 60 seconds. After that, the mixture was poured into a mold, cured under the curing conditions shown in Tables 1 to 4, and then cured at 23° C. for 3 weeks. A polyurethane resin was thus obtained. More specifically, a cast polyurethane elastomer was obtained by the above cast molding.

In addition, in Comparative Example 8, the pot life was short, and the polyurethane resin was not obtained because it cured during casting.

In Tables 1 to 4, the equivalent ratio R3 indicates the equivalent ratio R3 (NCO/active hydrogen group) of the isocyanate group in the prepolymer composition to the active hydrogen group in the chain extender.

Examples 11-12 and Comparative Examples 9-19
(1) Prepolymer preparation process The polyisocyanate component and polyol component described in Tables 5 and 6 are mixed under a nitrogen atmosphere, and the isocyanate group concentration (isocyanate group concentration after the prepolymer synthesis step) is described in Tables 5 and 6. The reaction was allowed to reach the value.

The equivalent ratio R1 (NCO/OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component is shown in the table.

As a result, a reaction product liquid containing an isocyanate group-terminated prepolymer was obtained as a prepolymer composition.

Furthermore, an antioxidant was added to the prepolymer composition according to the formulations shown in Tables 5 and 6.

(2) Chain elongation step With respect to 100 parts by mass of the prepolymer composition, 0.03 parts by mass of dibutyltin dilaurate (urethanization catalyst, DBTDL) is added, and if necessary, In the formulation, a light stabilizer was added and the prepolymer composition was preheated to 60°C and the chain extender was preheated to 40°C.

Then, the prepolymer composition and the chain extender were blended at the equivalent ratio R3 shown in Tables 5 and 6, mixed for 60 seconds, and degassed under reduced pressure at room temperature for 60 seconds. The mixture was then poured into a mold, cured under the curing conditions listed in Tables 5 and 6, and then cured at 23°C for 3 weeks. A polyurethane resin was thus obtained. More specifically, a cast polyurethane elastomer was obtained by the above cast molding.

In Tables 5 and 6, the equivalent ratio R3 indicates the equivalent ratio R3 (NCO/active hydrogen group) of the isocyanate group in the prepolymer composition to the active hydrogen group in the chain extender.

3. Evaluation <Polyurethane resin (cast polyurethane elastomer>

(1) A hardness and D hardness Shore A hardness and Shore D hardness of polyurethane resin were measured according to JIS K 7312 (1996).

(2) Tensile properties The tensile properties of the polyurethane resin were measured using a universal tensile tester (205N manufactured by Intesco) in accordance with JIS K 7312 (1996). That is, the polyurethane resin was cut to obtain a No. 3 dumbbell test piece. Then, 100% to 300% modulus (MPa), tensile strength (MPa) and elongation (elongation at break, %) were measured under conditions of tensile speed of 500 mm/min.

(3) Compression set The compression set of the polyurethane resin was measured according to JIS K 7312 (1996).

(4) Abrasion resistance (Taber abrasion amount)
The abrasion resistance of polyurethane resin was evaluated by the following method. That is, the surface of the polyurethane resin is abraded using a Taber abrasion tester (manufactured by Toyo Seiki Seisakusho) and an abrasion wheel H-22 under the conditions of a load of 1 kg and a rotation speed of 60 rpm and 1000 rpm, and the difference in mass before and after the test is measured. bottom. In addition, it was evaluated that the smaller the mass, the better the wear resistance.

(5) Discoloration Resistance Using a colorimeter (manufactured by Minolta Minolta, model: CR-200), the degree of yellowness of the surface of the polyurethane resin was measured. Also, the yellowness (b ^* value) was measured in the L ^* a ^* b ^* color space.

In the above measurements, the yellowness (b ^* value) of the polyurethane resin immediately after curing and the yellowness (b ^* value) of the polyurethane resin after curing and UV irradiation were measured.

In addition, UV irradiation complies with JIS D 0205 (1987) and WAL-2S. The environmental conditions for the ultraviolet irradiation were 50% humidity and 63°C panel temperature. Moreover, the ultraviolet irradiation time was 400 hours.

Each degree of yellowness (b ^* value) was evaluated according to the following criteria.

1 point: 7 ≤ b ^*
2 points: 5≤b ^* <7
3 points: 3≤b ^* <5
4 points: 1≤b ^* <3
5 points: b ^* <1

(6) Crack resistance (elongation retention rate)
The elongation retention rate of the polyurethane resin was measured according to JIS K 7312 (1996) using a universal tensile tester (205N manufactured by Intesco). That is, the polyurethane resin was cut to obtain a No. 3 dumbbell test piece. Then, the elongation (elongation at break, %) was measured under the condition of a tensile speed of 500 mm/min.

In the above measurements, the elongation (%) of the polyurethane resin after curing and before the heat resistance test (immediately after curing) and the elongation (%) of the polyurethane resin after curing and the heat resistance test were measured. In the heat resistance test, the polyurethane resin was heated at 110°C for 800 hours.

Then, the retention rate of elongation (%) was calculated by the following formula and evaluated according to the following criteria.
Elongation retention (%) = [elongation after heat resistance test (%)/elongation before heat resistance test (%)] × 100

1 point: elongation retention rate ≤ 20%
2 points: 20% <elongation retention rate ≤ 40%
3 points: 40% < elongation retention ≤ 60%
4 points: 60% <elongation retention rate ≤ 80%
5 points: 80% < elongation retention rate

Although the above invention has been provided as an exemplary embodiment of the present invention, this is merely an illustration and should not be construed as limiting. Variations of the invention that are obvious to those skilled in the art are intended to be included in the following claims.

The method for producing a polyurethane resin and the polyurethane resin of the present invention are suitably used in the fields of polyurethane elastomers, paints, coating agents and adhesives.

Claims (5)

A polyisocyanate component containing bis(isocyanatomethyl)cyclohexane and a polyol component containing a macropolyol are mixed so that the equivalent ratio (NCO/OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component exceeds 1.0. A prepolymer preparation step of obtaining a prepolymer composition containing an isocyanate group-terminated prepolymer by reacting at a ratio of
and a chain elongation step of reacting the prepolymer composition with a chain elongation agent to synthesize a polyurethane resin,
An antioxidant is added in the prepolymer preparation step and/or the chain elongation step,
The antioxidant comprises a hindered phenol-based antioxidant having a structure represented by the following formula (1) and a phosphorous acid-based antioxidant,
The proportion of the hindered phenol-based antioxidant is 0.30 parts by mass or more and 1.00 parts by mass or less with respect to 100 parts by mass of the prepolymer composition,
In the chain elongation step,
A method for producing a polyurethane resin, wherein the reaction temperature between the prepolymer composition and the chain extender is 120°C or higher and 140°C or lower.

(In the formula, R1 and R2 are the same or different and represent a monovalent branched hydrocarbon group having 3 to 6 carbon atoms.) The method for producing a polyurethane resin according to claim 1, wherein the hindered phenol-based antioxidant has one structure represented by the formula (1) in one molecule. 2. The method for producing a polyurethane resin according to claim 1, wherein the hindered phenol-based antioxidant has a structure represented by the following formula (2).

(In the formula, R1 and R2 are the same or different and represent a monovalent branched hydrocarbon group having 3 to 6 carbon atoms. R3 represents a divalent hydrocarbon group having 1 to 6 carbon atoms. .R4 represents a monovalent hydrocarbon group having 1 to 30 carbon atoms.) The method for producing a polyurethane resin according to claim 3, wherein R4 in the formula (2) represents a monovalent hydrocarbon group having 10 to 20 carbon atoms. Elongation at break measured in accordance with JIS K 7312 (1996) is 500% or more,
Compression set measured in accordance with JIS K 7312 (1996) is less than 30%,
The amount of Taber wear measured at a load of 1 kg, a rotation speed of 60 rpm and 1000 rotations is
is less than 100 mg;
The b ^* value measured after 400 hours of UV irradiation is less than 5,
A polyurethane resin, wherein the breaking elongation measured after heating at 110° C. for 800 hours exceeds 60% of the breaking elongation measured before the heating.