JPH0912669A - Polyurethane solution, polyurethane molding, and their production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stable polyurethane soln. which is prevented from coloration and viscosity change by reacting a mixture contg. a hydroxylic chain extender with an org. diisocyanate in a polar solvent in the presence of a specific compd. and a urethane-forming catalyst. SOLUTION: In producing a polyurethane soln. by reacting a mixture comprising a straight-chain compd. having two hydroxylic active hydrogen atoms and a mol.wt. of 250-4,000 and a hydroxylic chain extender with an org. diisocyanate in a polar solvent, the reaction is conducted in the presence of a urethane- forming catalyst and a hindered phenol (meth)acrylate represented by formula I [wherein R1 is a 1-4C alkyl; R2 and R3 are each a group represented by formula II (wherein R' is a 1-5C alkyl or phenyl); and R4 is H or methyl]. Thus, a polyurethane soln. can be produced without detriment to the productivity or merchandise value, though a chain extender having hydroxylic active hydrogen atoms is used. A molding obtd. by removing the polar solvent from the soln. has excellent physical properties and is suitable for producing a fiber or film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyurethane solution and a polyurethane molded product by a batch method.
Specifically, a molecular weight of 250 having two hydroxyl group active hydrogens
~ 4000 linear linear molecular diols (hereinafter referred to as polymeric diols), hydroxyl chain extenders and organic diisocyanates are reacted to produce transparent and stable polyurethane solutions with no coloration and excellent physical properties. And a method for producing a polyurethane molded article.

[0002]

2. Description of the Related Art Conventionally, from polyurethane solutions having substantially no crosslinked structure to elastic fibers, elastic films, various molded articles in the form of elastomers, surface coatings of artificial leather and various coatings, impregnating agents, etc. Various articles having excellent rubbery elasticity have been produced. In addition, it has the characteristics of higher mechanical strength and superior durability compared to natural rubber. This polyurethane solution is produced by reacting an organic diisocyanate with a diol having a relatively high molecular weight and a chain extender in a polar solvent, and then the solvent is removed to produce a molded article. The method using this solution can handle a system with high fluidity at room temperature compared to the method of molding by heating and melting solid polyurethane as it is, so it is generally easier to handle, and it is simpler in terms of equipment and process. There is a feature that can be manufactured.

However, when a compound having a hydroxyl group active hydrogen is used as the chain extender, the reactivity between the hydroxyl group and the isocyanate group is milder than that of the amine active hydrogen, and the final step of producing a polyurethane solution. However, the problem is that the number of hydroxyl groups and isocyanate groups at the ends of the reaction decreases, and the reaction time becomes very long due to an increase in viscosity, resulting in very poor productivity. As an example of using a hydroxyl chain extender in a solvent, JP-A-48-58095 discloses an example of reacting 1,4-butanediol with an organic diisocyanate in dioxane. It is described that dioxane is added after the reaction for time and the reaction is further performed for 5 hours.

Further, it is generally known that a urethane-forming catalyst such as a tertiary amine is used in combination when reacting a hydroxyl group active hydrogen with an isocyanate compound. Since the reaction time has a substantially linear relationship with the addition amount of the catalyst, the reaction time can be arbitrarily set by adjusting the amount of the catalyst. However, when producing a polyurethane solution, it is necessary to carry out the reaction in a polar solvent, and in the presence of an amine in the polar solvent, the polyurethane solution is colored, or the produced polyurethane solution thickens and becomes cloudy. This will significantly reduce the commercial value of the polyurethane solution.

The acrylic acid ester-containing hindered phenol used in the present invention is a known compound for synthetic rubber and synthetic resin applications, and is used as an antioxidant by being mixed into the synthetic rubber and synthetic resin after the synthetic reaction. To be
For example, Japanese Patent Application Laid-Open No. 58-84835 discloses a method for stabilizing oxidation of synthetic rubber, and Japanese Patent Application Laid-Open No. 59-71341 discloses a method for improving thermal oxidation stability and heat resistance stability of a synthetic resin. Japanese Patent Application Laid-Open No. 62-18445 discloses a method for improving the heat resistance of a butadiene-based polymer, and Japanese Patent Application Laid-Open Nos. 63-275684 and 277292 disclose a method for stabilizing a rubber latex adhesive against oxidation due to heat. Disclosed, Japanese Patent Laid-Open Nos. 1-168643 and 1-170
626, JP-A-1-172434 discloses a method for stabilizing a butadiene-based polymer, but it is a method for preventing oxidation due to heat by adding it to a molded polymer and is used in combination with a urethane-forming catalyst. Or
There is no description that it is added before the polyurethane synthesis reaction to suppress coloration and prevent thickening.

[0006]

The problem to be solved by the present invention is to improve the low productivity as described above, without lowering the commercial value of the polyurethane solution, and to provide a molding solution and a surface coating solution. As a coating solution, impregnating agent, or adhesive solution, it is transparent and has good stability, and there is no coloring or thickening.
This is to prevent deterioration of physical properties even when a polyurethane solution having good productivity is obtained and a solvent is removed to produce a molded product.

[0007]

Means for Solving the Problems As a result of intensive studies made by the present inventors in order to solve the above-mentioned problems, the problematic coloring results from the formation of a coloring substance by the reaction of an isocyanate compound and a polar solvent. It was found that an amine compound promotes the reaction. Suppressing side reactions other than this urethanization reaction and mixing hindered phenols containing acryl ester in order to maintain the activity of amine compounds for urethanization reaction causes problems such as coloring and viscosity change phenomena. The present invention has been completed by finding the surprising finding that a stable polyurethane solution can be produced without causing the above phenomenon and that the physical properties of the molded product are improved rather than lowered.

That is, the present invention provides the following (1) to (6).
It is as follows. (1) When a polyurethane solution is produced by reacting a mixture of a linear molecule having two hydroxyl group active hydrogens having a molecular weight of 250 to 4000 and a hydroxyl group extender in a polar solvent with an organic diisocyanate, Formula (I)

Embedded image [In the formula, R ₁ is an alkyl group having 1 to 4 carbon atoms, R ₂ and R ₃ are each independently —C (CH ₃ ) ₂ —R ′ (where R ′ is an alkyl group having 1 to 5 carbon atoms). Or a phenyl group), and R ₄ represents a hydrogen atom or a methyl group. ] The polyurethane solution characterized by adding and reacting both the hindered phenol containing the acrylic ester represented by these, and a urethanization catalyst. (2) In the general formula (I), R ₁ is a methyl group, R ₂ and R ₃
Is a tert-amyl group, R ₄ is a hydrogen atom, that is, the acrylic ester-containing hindered phenol represented by the general formula (I) is 2- (1- (2-hydroxy-3,5).
-Di-tert-pentylphenyl) ethyl) -4,6
-The polyurethane solution according to (1), which is di-tert-pentylphenyl acrylate. (3) A polyurethane molded product produced by removing the polar solvent from the polyurethane solution according to (1) or (2) by a wet or dry method. (4) When a polyurethane solution is produced by reacting a mixture of a linear molecule having two hydroxyl group active hydrogens having a molecular weight of 250 to 4000 with a hydroxyl group extender in a polar solvent and an organic diisocyanate, A method for producing a polyurethane solution, which comprises adding both a hindered phenol containing an acrylic ester represented by the formula (I) and a urethanization catalyst, and then reacting them. (5) In formula (I), R ₁ is a methyl group, R ₂ and R ₃
Is a tert-amyl group, R ₄ is a hydrogen atom, that is, the acrylic ester-containing hindered phenol represented by the general formula (I) is 2- (1- (2-hydroxy-3,5).
-Di-tert-pentylphenyl) ethyl) -4,6
-The method for producing a polyurethane solution according to (4), which is di-tert-pentylphenyl acrylate. (6) A method for producing a polyurethane molded article, which comprises removing the polar solvent from the polyurethane solution according to (1) or (2) by a wet or dry method.

The method for producing the polyurethane solution in the present invention is produced by the following two production methods similar to known methods. The first is the first step of producing an isocyanate-terminated prepolymer by the reaction of a polymeric diol and an organic diisocyanate, by dissolving the isocyanate-terminated prepolymer in a solvent and then charging a hydroxyl chain extender. A two-step synthetic method comprising a second step for carrying out a chain extension reaction,
The second is a one-stage reaction method in which a mixture of a polymer diol and a chain extender and an organic diisocyanate are reacted in a polar solvent.

The first step in the production of the polyurethane solution by the two-step synthesis method in the present invention is produced by reacting an excessive amount of organic diisocyanate in an equivalent ratio to the polymeric diol. The equivalent ratio of the organic diisocyanate to the polymeric diol is preferably 1.1 to 2.4, more preferably 1.4.
~ 2.0. When the equivalent weight is used, the molecular weight becomes substantially infinite in the first step, which may make subsequent production impossible, which is not preferable.

It does not matter which of the organic diisocyanate and the polymeric diol is charged at one time or which is charged in the first step as long as the reaction is carried out at a time sufficiently shorter than the time for the reaction to proceed. However, when the organic diisocyanate is added dropwise to the polymer diol little by little or is continuously charged by a metering pump or the like, the molecular weight will be practically infinite if charged for a long time, and care must be taken.

The reaction temperature in the first step is preferably 30 to 1
20 ° C, more preferably 50 to 80 ° C, 30 ° C
If the reaction temperature is lower, the reaction time will be longer, which is not industrially preferable, and if the reaction temperature is higher than 120 ° C., a large amount of side reactions such as the formation of alohanate bonds will occur, resulting in an increase in viscosity and gelation. It is not preferable because it may cause

In the one-step synthesis method of the present invention, a polymer diol, a chain extender and a polar solvent are mixed, and then an organic diisocyanate is added dropwise or inserted all at once to carry out a reaction to produce a polyurethane solution. . The sum of the equivalents of the polymeric diol and the hydroxyl chain extender and the equivalent of the organic diisocyanate are preferably 1.1 to 0.9. The reaction temperature may be any temperature at which the reaction proceeds mildly, but is 30 to 100 ° C, preferably 50 to 80 ° C.

The organic diisocyanate used in the present invention may be an organic diisocyanate usually used in polyurethane chemistry. For example, 2,4-
Tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate,
2,2'-diphenylmethane diisocyanate, 1,6
-Hexamethylene diisocyanate, naphthylene diisocyanate, or mixtures thereof. Preferably used, because of the physical properties of the molded product,
It is 4,4'-diphenylmethane diisocyanate (hereinafter referred to as MDI) containing 2,4'- and 2,2'-diphenylmethane diisocyanate. The MDI may be obtained as a solid or may be obtained and used in a molten state, but the MDI in a molten state is preferable because the melting operation can be omitted.

Examples of the polymer diol used in the present invention include polyether glycol, polyester glycol, copolymers and mixtures thereof.
If the molecular weight is less than 250, the elastic performance is poor, and if it exceeds 4000, it becomes difficult to produce polyether glycol or polyester glycol. The main types of suitable polyether glycols are polyalkylene ethers such as polytetramethylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, polyhexamethylene glycol and the like. Further, a random copolymer produced from a mixture of monomers used in producing these or a block copolymer produced by changing the production method can also be used. Polytetramethylene glycol is more preferably used than the physical properties of the molded product.

Polyester glycol is known as
It is obtained by polycondensation of a dibasic acid and a low molecular glycol.
Dibasic acids include succinic acid, adipic acid, speric acid,
Sebacic acid, terephthalic acid, hexahydroterephthalic acid, azelaic acid, etc. are used, and as low molecular glycols, ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol,
Neopentyl glycol, 1,6-hexamethylene glycol, cyclohexane-1,4-diol and the like can be used.

The solvent used in the present invention includes N, N-dimethylformamide, N, N-diethylformamide, N-methylformanilide, N-formylpiperidine, N, N-dimethylacetamide and N, which are known in polyurethane chemistry. , N-diethylacetamide, N, N
-N-substituted amides such as dimethylpropionamide, N-methyl-α-pyrrolidone, N-methyl-α-piperidone, N-methylcaprolactam, N-tetramethylurea, N-acetyl-α-pyrrolidone, N-acetyl- α
-N-substituted ureas such as piperidone and N-acetylcaprolactam, N-substituted thioureas such as N-tetramethylthiourea, dimethyl sulfoxide, tetramethylene sulfoxide, diethyl sulfoxide, diisopropyl sulfoxide, di-n-propyl sulfoxide, diisobutyl sulfoxide, di- Examples thereof include sulfoxods such as -n-butyl sulfoxide, and N-substituted phosphorylamides such as hexamethylphosphorylamide and hexaethylphosphorylamide. Further, since water in the solvent reacts with organic diisocyanate, it is desirable to dehydrate and purify using a dehydrating agent such as distillation or molecular sieves.

The hydroxyl chain extender in the present invention may be any one having a primary or secondary hydroxyl group capable of reacting with an isocyanate group, but low molecular diols, alkanolamines and the like may also be used. it can. The low molecular weight diol has two primary or secondary hydroxyl groups capable of reacting with an isocyanate, and a relatively low molecular weight diol having a molecular weight of 200 or less is used. For example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,5-pentanediol, 2,2 Known in polyurethanes such as dimethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,6-hexanediol. Compounds. Examples of the alkanolamine include ethanolamine, propanolamine and isopropanolamine.

The hindered phenol containing an acrylic acid ester in the molecule used in the present invention is, for example, 2-
tert-butyl-6- (3-tert-butyl-2-
Hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2- (1- (2-hydroxy-3,5
-Ditert-pentylphenyl) ethyl) -4,6-
Ditert-pentylphenyl acrylate, 2,4-
Ditert-butyl-6- (3,5-ditert-butyl-2-hydroxybenzyl) -phenyl acrylate, 2,4-ditert-pentyl-6- (3,5-ditert-butyl-2-hydroxy Benzyl) phenyl acrylate, 2- (1- (2-hydroxy-3,5-
Ditert-butylphenyl) ethyl) -4,6-dit
ert-butylphenyl acrylate, 2- (1- (2
-Hydroxy-3-tert-pentyl-5-tert
-Butylphenyl) ethyl) -4-tert-pentyl-6-tert-butylphenyl acrylate, 2-
(1- (2-hydroxy-3-tert-pentyl-5
-Tert-butylphenyl) ethyl) -4-tert
-Butyl-6-tert-pentylphenyl acrylate, and the like. The amount of hindered phenol containing acrylic acid ester in the molecule is 50ppm to 50000ppm with respect to the nonvolatile content of the polyurethane solution.
Is preferable, and when the amount is less than 50 ppm, the effect does not appear,
The effect does not change even if added in excess of 50,000 ppm. More preferably, it is 150 ppm to 30,000 ppm.

The hindered phenol containing an acrylic acid ester in the molecule used in the present invention may be added before the reaction of the organic diisocyanate with the chain extender in a polar solvent. It may be added to the solvent, or may be added to the raw material organic diisocyanate or polymer diol. The nonvolatile content is a value obtained by dividing the weight of the polymer obtained by removing the polar solvent from the polyurethane solution by the weight of the polyurethane solution, and is also called the polymer concentration. According to the method of the present invention, a spinning dope,
A polyurethane solution having a polymer concentration of 10% to 60%, which can be suitably used as a film or a solution for molding, can be produced.

As the urethanization catalyst used in the present invention, known tertiary amines and metal catalysts are used. Examples of tertiary amines include triethylenediamine, trimethylamine, triethylamine, diazabicyclooctane, N-methylmorpholine and N. -Ethylmorpholine, tetramethylethylenediamine, tetramethylpropanediamine, tetramethylhexanediamine, pentamethyldiethylenetriamine, bis (N, N-dimethylaminoethyl) ether, 2- (N- (dimethylaminoethoxyethyl) -N-methylamino) ) Ethanol and the like, and examples of the metal catalyst include dibutyltin dilaurate, stannas octoate, lead octylate and the like. In the present invention, known additives, for example,
Dyes, pigments, antioxidants, matting agents, antistatic agents, UV absorbers and the like can be added to the obtained polyurethane solution. In the present invention, as a method for removing the solvent when producing a molded product from the polyurethane solution, the polyurethane solution is put in water or a water / organic solvent mixed system,
A method of removing the solvent by dissolving may be used, or a method of putting the polyurethane solution in a vacuum at high temperature and removing the solvent by evaporation may be used. The shape of the molded article in the present invention can be formed into a film, a sheet, or a filament by a molding method.

[0022]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but these examples do not limit the present invention. Table 1 shows the results of Examples and Comparative Examples. In the examples, all parts and ratios are by weight unless otherwise specified.

The physical properties of the examples and comparative examples were measured by the following methods and devices. Measurement of physical properties of film: Tensile strength and elongation of the film were measured by Tensilon at 25 ° C. (elongation speed was 300 mm / min / min). Stress retention rate: The stress retention rate is calculated according to the following procedure. The test piece is stretched by 300%, left for 1 minute, then returned to its original position and left for 3 minutes. Repeat this to calculate the ratio of the stress after 5 minutes left for 1 minute and the stress at 1st 300% elongation by the following formula (JIS
L-1096 was applied). Stress retention = 100 × (TT ′) / T (T: stress at 300% elongation for the first time, T ′: stress after standing for 1 minute at the fifth time)

[0024]

[Table 1]

Comparative Example 1 In a reactor equipped with a torque meter, 800 parts of polytetramethylene glycol (hereinafter referred to as PTMEG) having a number average molecular weight of 1850, 234 parts of 1,4-butanediol (manufactured by Tosoh Corp.) and dehydration were used. N, N-dimethylacetamide (hereinafter referred to as DMAc) (Mitsubishi Gas Chemical Co., Inc.)
(Manufactured by K.K.) 3821 parts were charged and stirred. After stirring, 4,
4'-diphenylmethane diisocyanate (hereinafter 44M
99.3% and 2,4'-diphenylmethane diisocyanate (hereinafter referred to as 24MDI) 0.7.
% MDI (manufactured by Mitsui Toatsu Chemicals, Inc.) was added dropwise, and the reaction was carried out at 60 ° C. or lower. When the reaction was carried out after confirming by IR whether or not the isocyanate group remained, a transparent polyurethane solution was obtained at 60 ° C. for 3 hours after the completion of the addition of MDI. The polymer concentration after the reaction was 30%. The viscosity of this polyurethane solution immediately after production was 9200 cps at 25 ° C., and the hue was AP.
It was HA20.

After casting the produced polyurethane solution on a glass plate, it was dried at 100 ° C. for 6 hours to prepare a film having a thickness of 100 μm and subjected to a physical property test. As for the physical properties of the film, the tensile strength is 630 kg per square centimeter, the elongation is 580%, and the stress retention is 69.
%, And the physical properties were sufficiently high. Further, regarding the stability of the polyurethane solution, gelation and turbidity were not observed even after 4 weeks at 25 ° C.

Comparative Example 2 A reactor similar to Comparative Example 1 was charged in a reactor having a number average molecular weight of 1850.
800 parts TMEG, 234 parts 1,4-butanediol (manufactured by Tosoh Corporation), DMAc (Mitsubishi Gas Chemical Co., Inc.)
(Manufactured by K.K.) 3821 parts and triethylamine 0.6 parts were charged and stirred. After completion of stirring, 44MDI 99.3% and 24MD
MDI (manufactured by Mitsui Toatsu Chemicals, Inc.) consisting of 0.7%
642 parts was added dropwise, and the reaction was carried out at 60 ° C or lower.
When the reaction was carried out after confirming that the isocyanate group remained by IR, a transparent polyurethane solution was obtained by carrying out the reaction at 60 ° C. for 1 hour after the completion of the addition of MDI. It was confirmed that the reactivity was improved by about 3 times as compared with the case where no polar solvent containing no amine was used. The polymer concentration after the reaction was 30%. The viscosity of this polyurethane solution immediately after production was 8500 cp at 25 ° C.
and the hue was APHA450.

After casting the produced polyurethane solution on a glass plate, it was dried at 100 ° C. for 6 hours to prepare a film having a thickness of 100 μm, and the film was subjected to a physical property test. As for the physical properties of the film, the tensile strength is 560 kg per square centimeter, the elongation is 520%, and the stress retention rate is 61.
%, And the physical properties were not satisfactory. Further, regarding the stability of the polyurethane solution, gelation did not occur at 25 ° C. for 4 weeks, but turbidity that could be visually confirmed occurred after 2 weeks.

Example 1 The same reactor as in Comparative Example 1 was charged with PT having a number average molecular weight of 1850.
800 parts of MEG, 234 parts of 1,4-butanediol (manufactured by Tosoh Corporation), DMAc (Mitsubishi Gas Chemical Co., Inc.)
Manufactured) 3821 parts, triethylamine 0.9 parts, 2- (1
-(2-Hydroxy-3,5-ditert-pentylphenyl) ethyl) -4,6-ditert-pentylphenylacrylate (trade name: Sumilizer GS; manufactured by Sumitomo Chemical Co., Ltd.) 0.4 part And stirred. After stirring,
44MDI 99.3% and 24MDI 0.7%,
642 parts of MDI (manufactured by Mitsui Toatsu Chemicals, Inc.) was added dropwise, and the reaction was carried out at 60 ° C or lower. When the reaction was carried out after confirming that the isocyanate group remained by IR, a transparent polyurethane solution was obtained by carrying out the reaction at 60 ° C. for 1 hour after the completion of the addition of MDI. That is, the activity of the amine for the urethanization reaction hardly changed. The polymer concentration after the reaction was 30%.
The viscosity of this polyurethane solution immediately after production is 90 at 25 ° C.
It was 00 cps and the hue was APHA20.

Further, after casting the produced polyurethane solution on a glass plate, it was dried at 100 ° C. for 6 hours to prepare a film having a thickness of 100 μm and subjected to a physical property test. As for the physical properties of the film, the tensile strength is 630 kg per square centimeter, the elongation is 580%, and the stress retention is 69.
%, The physical properties were sufficiently high, and the physical properties were higher than those of Comparative Example 3 using a new polar solvent. Further, regarding the stability of the polyurethane solution, gelation and turbidity were not observed even after 4 weeks at 25 ° C.

Example 2 2- (1- (2-hydroxy-) used in Example 1
3,5-ditert-pentylphenyl) ethyl)-
Instead of 4,6-ditert-pentylphenyl acrylate, 2-tert-butyl-6- (3-tert
-Butyl-2-hydroxy-5-methylbenzyl) -4
A polyurethane solution was prepared and cast into a film in exactly the same manner except that methylphenyl acrylate (trade name: Sumilizer GM; manufactured by Sumitomo Chemical Co., Ltd.) was used. The reaction is 60 ℃ after completion of MDI addition
When the reaction was carried out for 1 hour, absorption of isocyanate group was not observed by IR. The viscosity of the polyurethane solution immediately after production was 8600 cps at 25 ° C., and the hue was AP.
It was HA20. The tensile strength of the film is 6
30 kg per square centimeter, elongation was 600%, stress retention was 71%, and the physical properties were sufficiently high, and the physical properties were higher than those of Comparative Example 3 using a new polar solvent.

Example 3 A polyurethane solution was prepared and cast into a film in exactly the same manner except that diazabicyclooctane was used in place of the triethylamine used in Example 1. The reaction is 45 at 60 ° C after the addition of MDI.
By reacting for a minute, absorption of isocyanate group was not seen by IR. The viscosity of the polyurethane solution immediately after production was 9200 cps at 25 ° C., and the hue was APHA.
20. The tensile strength of the film is 650.
kg / square centimeter, elongation was 580%, stress retention was 70%, and the physical properties were sufficiently high.

[0033]

According to the present invention, even if a chain extender having a hydroxyl group active hydrogen is used, productivity is not reduced, and
A polyurethane solution can be produced without lowering the commercial value, and the molded product obtained by removing the polar solvent exhibits excellent physical properties, and is therefore suitable as a production method for producing synthetic fibers and films. Is.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location D06M 15/564 D06M 15/564 (72) Inventor Hiroshi Takayanagi 1190, Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (6)

[Claims] 1. A method for producing a polyurethane solution by reacting a mixture of a linear molecule having a molecular weight of 250 to 4000 having two hydroxyl group active hydrogens and a hydroxyl group chain extender with an organic diisocyanate in a polar solvent. , The general formula (I): [In the formula, R ₁ is an alkyl group having 1 to 4 carbon atoms, R ₂ and R ₃ are each independently —C (CH ₃ ) ₂ —R ′ (where R ′ is an alkyl group having 1 to 5 carbon atoms). Or a phenyl group), and R ₄ represents a hydrogen atom or a methyl group. ] The polyurethane solution characterized by adding and reacting both the hindered phenol containing the acrylic ester represented by these, and a urethanization catalyst. 2. In the general formula (I), R ₁ is a methyl group, R ₂ and R ₃ are tert-amyl groups, and R ₄ is a hydrogen atom, that is, containing an acrylic ester represented by the general formula (I). Hindered phenol is 2- (1- (2-hydroxy-
3,5-di-tert-pentylphenyl) ethyl)-
The polyurethane solution according to claim 1, which is 4,6-di-tert-pentylphenyl acrylate. 3. A polyurethane molded article produced by removing the polar solvent from the polyurethane solution according to claim 1 or 2 by a wet or dry method. 4. A process for producing a polyurethane solution by reacting a mixture of a linear molecule having a molecular weight of 250 to 4000 having two hydroxyl group active hydrogens and a hydroxyl group chain extender with an organic diisocyanate in a polar solvent. A method for producing a polyurethane solution, comprising adding both a hindered phenol containing an acrylic acid ester represented by the general formula (I) and a urethanization catalyst, and then reacting them. 5. In the general formula (I), R ₁ is a methyl group, R ₂ and R ₃ are tert-amyl groups, and R ₄ is a hydrogen atom, that is, containing an acrylic ester represented by the general formula (I). Hindered phenol is 2- (1- (2-hydroxy-
3,5-di-tert-pentylphenyl) ethyl)-
The method for producing a polyurethane solution according to claim 4, which is 4,6-di-tert-pentylphenyl acrylate. 6. A method for producing a polyurethane molded article, which comprises removing the polar solvent from the polyurethane solution according to claim 1 or 2 by a wet or dry method.