JP2019001952A - Carboxy group-containing polycarbonate polyurethane resin composition and method for producing the same - Google Patents

Abstract

To simply provide a polyurethane that has improved functions such as hygroscopicity, adhesiveness and water dispersion, and has high durability and flexibility.SOLUTION: A carboxy group-containing polycarbonate polyurethane resin composition is obtained by the chain elongation of a prepolymer compound obtained by the reaction of a carboxy group-containing polycarbonate polyol, which is obtained by the reaction between a tetracarboxylic acid or an anhydride thereof and polycarbonate polyol, with polyisocyanate.SELECTED DRAWING: None

Description

  The present invention relates to a novel carboxy group-containing polycarbonate system obtained by chain-extending a prepolymer obtained by the reaction of a carboxy group-containing polycarbonate polyol and a polyisocyanate obtained by reacting a tetracarboxylic acid or an anhydride thereof with a polycarbonate polyol. The present invention relates to a polyurethane resin composition and a method for producing the same.

  Polyurethane is composed of a crystalline hard segment having a strong cohesive force and an amorphous soft segment having a low cohesive force, and exhibits a specific function such as high elastic modulus (Non-patent Document 1). As the polyol forming the soft segment, polyether polyol, polyester polyol, polycarbonate polyol, or the like is used. Polyurethanes using polycarbonate polyols are excellent in terms of overall durability such as light resistance, heat resistance and hydrolysis resistance, but tend to be inferior in flexibility.

  As a method for controlling the physical properties of polyurethane, it is known to introduce a functional group. For example, it is known to introduce a carboxy group (Patent Document 1). When a carboxy group is introduced into polyurethane, functions such as hygroscopicity, adhesiveness, water dispersibility, water resistance, and film thickening are improved (Patent Documents 2 and 3). However, when a carboxy group is directly introduced with a low molecular weight carboxy group-containing polyol such as dimethylolpropionic acid (DMPA), the hard segment is increased by reaction with polyisocyanate. For this reason, the flexibility tends to be further impaired. Such polyurethane resins are generally not suitable for applications requiring flexibility such as synthetic leather and textile printing.

  As an example in which a carboxy group is introduced into a polyurethane soft segment, a polycaprolactone diol is synthesized by ring-opening polymerization of dihydroxycarboxylic acid and caprolactone, and a polyurethane is produced by reacting with polyisocyanate (Patent Document 4).

JP-A-3-50224 Japanese Patent Laid-Open No. 4-198361 JP2013-60582A JP-A-6-313024

Sanyo Chemical News (1) 2012 Spring No. 471

However, the conventionally known methods for introducing carboxy have an effect of reducing the hard segment, but as a result of containing many ester bonds inferior in hydrolysis resistance in the molecule, satisfactory physical properties cannot be obtained. There was a problem.
An object of the present invention is to easily provide a highly durable and flexible polyurethane having improved functions such as hygroscopicity, adhesiveness and water dispersibility.

（式中、Ｒ^１は、炭素数１〜２０のテトラカルボン酸からカルボキシ基を除いた基であり、Ｒ^２は、数平均分子量４，８００以下のポリカーボネートジオールから水酸基を除いた基であり、ｎは１〜１０の整数である）で表され、数平均分子量１０，０００以下である、前記［１］記載のカルボキシ基含有ポリカーボネート系ポリウレタン樹脂組成物。
［３］前記テトラカルボン酸又はその無水物がジフェニルテトラカルボン酸又はその無水物である、前記［１］又は［２］記載のカルボキシ基含有ポリカーボネート系ポリウレタン樹脂組成物。
［４］有機溶媒中、有機アミン触媒存在下、１２０℃以下でテトラカルボン酸無水物とポリカーボネートポリオールの反応を固形分濃度２０％以上の濃度で行う工程、次いでポリイソシアネートの反応によりプレポリマー化合物を合成する工程、次いで鎖伸長剤により鎖伸長する工程を含む、カルボキシ基含有ポリカーボネート系ポリウレタン樹脂組成物のワンポット製造方法。 In order to solve these problems, as a result of intensive studies, the above-mentioned problems include the following [1] to [4], and the carboxy group obtained by the reaction of tetracarboxylic acid or its anhydride and polycarbonate polyol. It has been found that the problem can be solved by a carboxy group-containing polycarbonate-based polyurethane resin composition obtained by chain-extending a prepolymer obtained by the reaction of a containing polycarbonate diol and a polyisocyanate.
[1] Carboxy group-containing polycarbonate-based polyurethane resin obtained by chain-extending a prepolymer compound obtained by reaction of carboxy group-containing polycarbonate polyol obtained by reaction of tetracarboxylic acid or its anhydride and polycarbonate polyol with polyisocyanate Composition.
[2] The carboxy group-containing polycarbonate polyol is represented by the following general formula (1):

(In the formula, R ¹ is a group obtained by removing a carboxy group from a tetracarboxylic acid having 1 to 20 carbon atoms, R ² is a group obtained by removing a hydroxyl group from a polycarbonate diol having a number average molecular weight of 4,800 or less, n is an integer of 1 to 10, and the number average molecular weight is 10,000 or less, the carboxy group-containing polycarbonate polyurethane resin composition according to [1].
[3] The carboxy group-containing polycarbonate polyurethane resin composition according to [1] or [2], wherein the tetracarboxylic acid or an anhydride thereof is diphenyltetracarboxylic acid or an anhydride thereof.
[4] A step of reacting a tetracarboxylic acid anhydride with a polycarbonate polyol in an organic solvent in the presence of an organic amine catalyst at a temperature of 120 ° C. or lower at a solid content concentration of 20% or higher, and then reacting the polyisocyanate with a prepolymer compound. A one-pot manufacturing method of a carboxy group-containing polycarbonate-based polyurethane resin composition, comprising a step of synthesizing and then a step of chain extension with a chain extender.

  Since the carboxy group is introduced as a soft segment by using a carboxy group-containing polycarbonate polyol in the polyurethane resin composition of the present invention, the ratio of hard segments is suppressed and softened. On the other hand, since most of the soft segment molecular chains are carbonate bonds, the durability is high. Moreover, the method for preparing the polyurethane resin composition of the present invention can be carried out in one pot and is simple.

  Next, the embodiment of the present invention will be described in the order of the carboxy group-containing polycarbonate-based polyurethane resin composition of the present invention and the production method thereof.

<Carboxy group-containing polycarbonate-based polyurethane resin composition>
The carboxy group-containing polycarbonate polyurethane resin composition of the present invention is obtained by chain-extending a prepolymer obtained by the reaction of a carboxy group-containing polycarbonate polyol and a polyisocyanate obtained by a reaction of a tetracarboxylic acid or an anhydride thereof and a polycarbonate polyol. can get. Details of each component are as follows.
The polymer compound as in the present invention is a product having a number of structures obtained by reaction of a plurality of types of raw material compounds. Therefore, a polymer compound is not uniquely indicated by its structure even if a large number of structures included can be described by a general formula. In addition, it is difficult to directly measure and specify the physical properties by instrumental analysis or the like and to distinguish them from existing compounds. Therefore, in the present invention, the “polyurethane resin composition” is specified by a production method as necessary.

[Tetracarboxylic acid]
The tetracarboxylic acid that is a raw material of the polyurethane resin composition of the present invention is a compound having four carboxy groups in one molecule, and may be an acid anhydride obtained by causing a dehydration reaction. As an organic group which remove | excluding the carboxy group from tetracarboxylic acid, the substituent may be included, a C6-C30 aromatic hydrocarbon group, a C3-C30 alicyclic hydrocarbon group, carbon number. Examples thereof include, but are not limited to, an aliphatic group having 1 to 30 and / or a group consisting of a heterocyclic ring having 1 to 30 carbon atoms. Here, the carbon number includes the carbon number of the substituent. Preferred examples of the tetracarboxylic acid or its anhydride that can be used include pyromellitic dianhydride and diphenyltetracarboxylic dianhydride, and more preferably 3,3 ′, 4,4′-diphenyltetracarboxylic. Acid dianhydride (BPDA).

[Polycarbonate polyol]
The polycarbonate polyol preferably has a number average molecular weight of 450 to 4800, more preferably 450 to 4000. When the number average molecular weight is less than the above range, the mass ratio of the alkylene chain derived from the polycarbonate in the carboxy group-containing polycarbonate polyol may decrease, and the flexibility of the cured film may decrease. The acid value of the polycarbonate polyol is decreased, and the crosslink density of the cured film may be decreased. As the polycarbonate polyol, polycarbonate diol is preferable. As the diol compound in the polycarbonate diol, an aliphatic diol or an alicyclic diol is preferably used. Examples thereof include a diol having a linear or side chain having 2 to 10 carbon atoms. For example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9 -Nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-methyl-1,8-octanediol And alicyclic diols such as 1,4-cyclohexanedimethanol. Among these diols, 1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol, which are less volatile at high temperatures and under vacuum during polymerization of polycarbonate diol, are preferred. Polycarbonate polyols may be used alone or in combination.

式中、Ｒ^１、Ｒ^２及びｎは、前記と同義である。カルボキシ基含有ポリカーボネートポリオールの数平均分子量は、原料となるポリカーボネートポリオールの分子量によって変動するが、１０，０００以下であることが好ましい。 When synthesized using one kind of tetracarboxylic acid or its anhydride and one kind of polycarbonate diol, the carboxy group-containing polycarbonate polyol can be represented by the following general formula (1).

In the formula, R ¹ , R ² and n are as defined above. The number average molecular weight of the carboxy group-containing polycarbonate polyol varies depending on the molecular weight of the polycarbonate polyol as a raw material, but is preferably 10,000 or less.

[Polyisocyanate]
The polyisocyanate compound is not particularly limited, but a diisocyanate compound having two isocyanate groups per molecule is preferable.
Specifically, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, 4,4′-diphenylenemethane diisocyanate (MDI), 2,4-diphenylmethane diisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane Aromatic polyisocyanate compounds such as 1,5-naphthylene diisocyanate, m-isocyanatophenylsulfonyl isocyanate, p-isocyanatophenylsulfonyl isocyanate; ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (H I), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, bis (2-isocyanatoethyl) Aliphatic polyisocyanate compounds such as fumarate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate; isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (Hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis (2-isocyanatoethyl) -4-cyclohexene-1,2-dicarboxylate, 2 5-norbornane diisocyanate, alicyclic polyisocyanate compounds such as 2,6-norbornane diisocyanate. These polyisocyanate compounds may be used alone or in combination of two or more.

[Chain extender]
The chain extender is not particularly limited. For example, hydrazine, ethylenediamine, 1,4-tetramethylenediamine, 2-methyl-1,5-pentanediamine, 1,6-hexamethylenediamine, 1,4-hexamethylenediamine , Polyamine compounds such as 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 1,3-bis (aminomethyl) cyclohexane, xylylenediamine, piperazine, 2,5-dimethylpiperazine, diethylenetriamine, triethylenetetramine, Examples thereof include polyol compounds such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,6-hexanediol, water, and the like. Among these, primary diamine compounds are preferable. These may be used alone or in combination of two or more.

<Method for producing carboxy group-containing polycarbonate-based polyurethane resin composition>
(Method for producing carboxy group-containing polycarbonate polyol)
For example, a carboxy group-containing polycarbonate polyol can be synthesized by an esterification reaction of a tetracarboxylic acid or an anhydride thereof and a polycarbonate polyol at 120 ° C. or lower in the presence of an organic amine catalyst. The tetracarboxylic acid or its anhydride and the polycarbonate polyol that can be used are as described above.

  As the organic amine catalyst used in the esterification reaction, those known to those skilled in the art can be used, for example, pyridine, picoline, trimethylamine, triethylamine, triethylenediamine, N, N-dimethylbenzylamine, N-methylmorpholine, 1 , 8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4.3.0] -5-nonene, N, N-dimethylaminopyridine and the like. Particularly preferred is triethylamine. The amount of the organic amine catalyst used is preferably 0.001 to 5 mol, more preferably 0.01 mol to 3 mol, per 1 mol of tetracarboxylic acid or dianhydride thereof.

This reaction is usually carried out by adding tetracarboxylic anhydride, polycarbonate polyol, or an organic solvent that does not react with isocyanate groups used in prepolymerization. Examples of organic solvents that can be used include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone, methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, and butyl acetate. , Organic acid esters such as methyl propionate, ethyl propionate, propyl propionate and butyl propionate, aromatic organic solvents such as benzene and toluene, N, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, etc. Can do. These organic solvents may be used alone or in combination of two or more.
The solvent can be added in such an amount that the resulting solid content concentration is 1 to 100%.

  The esterification reaction is usually performed at 0 to 120 ° C. If it is carried out at 120 ° C. or higher, side reactions such as esterification of carboxylic acid, formation of vinyl group by dehydration of hydroxyl group, and formation of ether group by decarbonylation of carbonate group proceed, which is not preferable. The reaction temperature is preferably 10 to 100 ° C.

(Prepolymerization reaction)
Prepolymerization is performed by adding polyisocyanate to the carboxy group-containing polycarbonate diol obtained by the esterification reaction. The solid content concentration of the carboxy group-containing polycarbonate diol used is preferably 20% or more from the reaction rate, the concentration of the intended practical polyurethane liquid, and the like, and it is used by concentrating in advance if necessary. An organometallic catalyst is usually added to the prepolymerization reaction, but it may not be added. As the organometallic catalyst, a tin catalyst is preferable. Particularly preferred as a tin catalyst is dibutyltin dilaurate. Since a tin catalyst is concerned about safety, it is preferable to use it at 0.24% or less. Particularly preferably, it is 0.1% or less. The reaction temperature is 0 to 120 ° C, preferably 10 to 100 ° C.

  In the prepolymerization reaction, the same or other polyol can be added to adjust the molecular weight, acid value, etc. of the prepolymer. The polyol is not particularly limited, and examples thereof include polyester polyol, polycarbonate diol, aliphatic diol, alicyclic diol, aromatic diol, and polyfunctional polyol. Aliphatic diols, alicyclic diols, and polycarbonate diols can be used to increase the breaking energy in tension and the water resistance of the coating film.

  The types of polyisocyanate and polycarbonate diol used for prepolymerization are as described above. The amount of polyisocyanate to be used is preferably NCO / OH molar ratio in the prepolymerization reaction and is 2.0 / 1.0 to 1.1 / 1.0.

(Chain elongation reaction (polyurethane))
The obtained prepolymer is chain-extended with a chain extender to form polyurethane. The chain extender used is as described above. In this reaction, a solvent can be used. As the solvent, the organic solvent or water mentioned in the prepolymerization can be used. When water is used, a base such as triethylamine is used for dispersion. The reaction temperature is preferably 10 to 100 ° C. Preferably, it is 10-80 degreeC.

(One-pot synthesis of carboxy group-containing polycarbonate polyurethane resin composition (high concentration method))
In the synthesis of carboxy group-containing polycarbonate diols, acid dianhydrides have a high melting point and are often insoluble in solvents. In order to dissolve acid dianhydrides and react in a homogeneous system, a large amount of solvent is used. Therefore, it was necessary to design and react at a solid content concentration as low as 5% or less. Therefore, in order to obtain a polyurethane resin composition having a practical concentration, first, a low concentration carboxy group-containing polycarbonate diol is synthesized, and then the solvent is distilled off from the reaction solution to obtain a high concentration carboxy group containing polycarbonate diol solution. Then, it was necessary to carry out a urethanization reaction. This method requires a vacuum concentration step of the solvent, has poor production efficiency, and has a problem in that the water concentration is high because the water is concentrated during the concentration, and there are many side reactions during the urethanization reaction.
In the synthesis of a carboxy group-containing polycarbonate diol, even when the acid dianhydride is almost insoluble in the solvent at the beginning, it is gradually dissolved by reaction using an organic amine catalyst, resulting in uniform and low moisture content. It was found that a high-concentration carboxy group-containing polycarbonate diol solution can be obtained with good quality. This eliminates the need for a solvent distillation step, enables continuous prepolymerization and chain extension, and constructed a one-pot synthesis method from esterification of tetracarboxylic acid to polyurethane.
That is, in the presence of an organic amine catalyst, synthesis of a carboxy group-containing polycarbonate polyol by reaction of tetracarboxylic acid or its anhydride and polycarbonate polyol at a temperature of 120 ° C. or less is carried out at a solid content concentration of 20% or more, followed by pre-reaction by reaction of polyisocyanate. A carboxy group-containing polycarbonate-based polyurethane resin composition can be produced in one pot by synthesizing a polymer compound and extending the chain.
The concentration of the solid component during the synthesis of the carboxy group-containing polycarbonate polyol is 20% or more, preferably 30% or more, more preferably 40% or more. In other embodiments, the production of the carboxy group-containing polycarbonate polyol is described above. It is the same as the method.

  Hereinafter, although the specific aspect of this invention is explained in full detail by an Example and a comparative example, this invention is not intended to be limited to these.

Synthesis of carboxylic acid-containing polycarbonate diol by reaction of tetracarboxylic anhydride and polycarbonate polyol Example 1 BPDA-UH50 adduct DMAP salt solution (BPDA: UH50 = 1: 2 (molar ratio), solid content concentration 5%)
BPDA 2.9 g, ETERNACOLL UH-50 (registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 500; hydroxyl value 224 mg KOH / g; polycarbonate diol obtained by reacting 1,6-hexanediol and dimethyl carbonate) 10 0.5 g and 2.4 g of N, N-dimethyl-4-aminopyridine (DMAP) were dissolved in 294 g of NMP and reacted at room temperature for 5 hours in a nitrogen atmosphere. The increase in molecular weight was monitored by GPC measurement, and the completion of the reaction was confirmed to obtain a target solution having a solid content concentration of 5%.
The acid value was 3.7 mgKOH / g, and the OH value was 4.0 mgKOH / g (both solutions).

Example 2 BPDA-UH50 adduct DMAP salt solution (BPDA: UH50 = 1: 2 (molar ratio), solid content concentration 43%)
The BPDA-UH50 adduct solution of Example 1 (molar ratio 1: 2, solid content concentration 5%) was evaporated under reduced pressure (0.1 hPa, 35 ° C.) to obtain the desired product having a solid content concentration of 43%. . ^{From 1} H-NMR (CDCl ₃ ), the signal of the methylene group adjacent to the ester bond (δ = 4.33 ppm) generated by the reaction between the polycarbonate diol and BPDA, and the signal of the methylene group adjacent to the terminal hydroxy group of the polycarbonate diol. Comparison of the integration ratio with (δ = 3.6 ppm) confirmed the production of the target product.

Example 3 BPDA-UH50 adduct TEA salt solution (BPDA: UH50 = 1: 2 (molar ratio), solid content concentration 5%)
BPDA 0.33 g, ETERNACOLL UH-50 (registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 500; hydroxyl value 224 mg KOH / g; polycarbonate diol obtained by reacting 1,6-hexanediol and dimethyl carbonate) 1 .1 g and 0.3 g of TEA were dissolved in 32 g of NMP and reacted at room temperature for 6 hours under an argon atmosphere. A target solution having a solid content concentration of 5% was obtained.

Example 4 BPDA-UH50 adduct TEA salt solution (BPDA: UH50 = 1: 2 (molar ratio), solid content concentration 50%)
BPDA 0.3 g, ETERNACOLL UH-50 (registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 500; hydroxyl value 224 mg KOH / g; polycarbonate diol obtained by reacting 1,6-hexanediol and dimethyl carbonate) 1 0.0 g and 0.3 g of TEA were suspended in 1.6 g of NMP and stirred at room temperature under an argon atmosphere. Although it was in a suspended state at the beginning of the reaction, it gradually dissolved and became a homogeneous solution. After reacting for 8 hours, a target solution having a solid content concentration of 50% was obtained.

Example 5 BPDA-UH200 adduct TEA salt solution (BPDA: UH200 = 1: 2 (molar ratio), solid content concentration 50%)
BPDA 1.5 g, ETERNACOLL UH-200 (registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 2,000; hydroxyl value 56.1 mg KOH / g; obtained by reacting 1,6-hexanediol with dimethyl carbonate Polycarbonate diol) 20.5 g and TEA 1.0 g were suspended in 23.4 g of NMP and stirred at room temperature in an argon atmosphere. Although it was in a suspended state at the beginning of the reaction, it gradually dissolved and became a homogeneous solution. After reacting for 8 hours, a target solution having a solid content concentration of 50% was obtained.
The acid value was 11.9 mgKOH / g, and the OH value was 14.5 mgKOH / g (both solutions).

Example 6 BPDA-UH200 adduct TEA salt solution (BPDA: UH200 = 1: 2 (molar ratio), solid content concentration 75%)
4.2 g of BPDA, ETERNACOLL UH-200 (registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 2,000; hydroxyl value 56.1 mg KOH / g; obtained by reacting 1,6-hexanediol with dimethyl carbonate (Polycarbonate diol) (83 g) was suspended in NMP (25 g) and stirred in an oil bath at 45 ° C. under an argon atmosphere. A solution of TEA 3 g-NMP 6 g was added to this suspension and reacted. Although it was in a suspended state at the beginning of the reaction, it gradually dissolved and became a homogeneous solution. After reacting for 7 hours, a target solution having a solid content concentration of 75% was obtained.
The acid value was 13.6 mgKOH / g and the OH value was 28.6 mgKOH / g (both solutions).

Example 7 Synthesis of BPDA-UH200-polyurethane (one-pot production method of carboxylic acid-containing polycarbonate-based polyurethane resin composition)
4.2 g of BPDA, ETERNACOLL UH-200 (registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 2,000; hydroxyl value 56.1 mg KOH / g; obtained by reacting 1,6-hexanediol with dimethyl carbonate 83.5 g of polycarbonate diol) and 2.9 g of TEA were suspended in 30 g of NMP, heated and stirred at 40 ° C. for 7 hours under a nitrogen atmosphere, and BPDA-UH200 adduct TEA salt solution (BPDA: UH200 = 1: 2 (molar ratio)) Solid content concentration 75%) was obtained. The temperature was raised to 60 ° C., 8.3 g of IPDI and 0.08 g of DBTDL were added, and the mixture was reacted at 80 ° C. for 8 hours to obtain a prepolymer. After cooling to room temperature, 3.2 g of 35% MPMD solution (NMP) was gradually added to obtain the target carboxy group-containing polycarbonate-based polyurethane resin BPDA-UH200-polyurethane. The weight average molecular weight was 265,000.

Comparative Example 1 Polyurethane ETERRNACOLL UH-200 using dimethylolpropanoic acid as it is (registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 2000; hydroxyl value 56.1 mgKOH / g; 1,6-hexanediol and dimethyl carbonate 56.5 g of polycarbonate diol obtained by the reaction) and 11.2 g of NMP were heated and stirred at 60 ° C. After adding 15.6 g of isophorone diisocyanate, the mixture was heated at 80 ° C. for 1 hour, and 3.1 g of dimethylolpropanoic acid was added and heated at 90 ° C. for 3.5 hours to obtain a prepolymer containing both terminal isocyanate groups.
The temperature was returned to room temperature, 423 g of NMP was added, 6.2 g of 35% 5-methylpentamethylenediamine (NMP solution) was gradually added, chain extension was performed, and a carboxy group-containing polycarbonate polyurethane resin composition was obtained. The weight average molecular weight was 168,000.

[Manufacture of polyurethane film]
A good coating layer was obtained by applying the polyurethane resin composition of Example 7 and Comparative Example 1 on a glass plate as a coating composition and drying at 80 ° C. for 3 hours and 120 ° C. for 3 hours. The obtained coating layer was peeled off to prepare a polyurethane film. The film thickness of the obtained polyurethane film is 0.1 mm. Table 1 shows the tensile properties of each polyurethane film.

From Table 1, it can be seen that the polyurethane using the carboxy group-containing polycarbonate diol obtained by the reaction of the tetracarboxylic acid anhydride and the polycarbonate diol has improved flexibility as compared with the conventionally used polyurethane introduced with a carboxy group.
According to the present invention, a polyurethane having improved flexibility, weather resistance, hygroscopicity and the like can be obtained. Therefore, the polyurethane resin composition of the present invention is useful as a raw material for artificial leather, synthetic leather and the like.

Claims (4)

  A carboxy group-containing polycarbonate-based polyurethane resin composition obtained by chain-extending a prepolymer compound obtained by a reaction of a carboxy group-containing polycarbonate polyol obtained by a reaction of tetracarboxylic acid or an anhydride thereof and a polycarbonate polyol with a polyisocyanate. The carboxy group-containing polycarbonate polyol is represented by the following general formula (1):

(In the formula, R ¹ is a group obtained by removing a carboxy group from a tetracarboxylic acid having 1 to 20 carbon atoms, R ² is a group obtained by removing a hydroxyl group from a polycarbonate diol having a number average molecular weight of 4,800 or less, The carboxy group-containing polycarbonate-based polyurethane resin composition according to claim 1, wherein n is an integer of 1 to 10 and has a number average molecular weight of 10,000 or less.   The carboxyl group-containing polycarbonate-based polyurethane resin composition according to claim 1 or 2, wherein the tetracarboxylic acid or an anhydride thereof is diphenyltetracarboxylic acid or an anhydride thereof.   A step of reacting a tetracarboxylic acid anhydride and a polycarbonate polyol in an organic solvent in the presence of an organic amine catalyst at a temperature of 120 ° C. or less at a solid content concentration of 20% or more, and then a step of synthesizing a prepolymer compound by a reaction of polyisocyanate. Then, the one-pot manufacturing method of the carboxyl group-containing polycarbonate-type polyurethane resin composition including the process of extending | stretching with a chain extender.