JP3204340B2 - Method for producing polyurethane resin - Google Patents

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 resin having excellent properties as synthetic leather.

[0002]

2. Description of the Related Art At present, polyurethane resin solutions are widely used for synthetic leather by a wet film forming method.

[0003] As a method, relatively low concentration (20%
The following coagulation bath of an aqueous solution of a polyurethane resin solvent is applied, and recovery of a used low-concentration polyurethane resin solvent is performed by each processing manufacturer.

In general, despite the fact that a high-concentration aqueous solution coagulation bath is preferable for enhancing the physical properties (flexibility, tensile strength, etc.) of a wet film, the reason why a low-concentration aqueous solution coagulation bath is used is that the current coagulation bath is used. This is because in the case of the polyurethane resin composition, the rate of solvent removal from the polyurethane resin solution in the high-concentration solvent coagulation bath is slow and cannot be sufficiently removed, so that a smooth film cannot be formed. Therefore, the fact is that a low-concentration aqueous solution coagulation bath is reluctantly used as a wet film formation method.

On the other hand, the main physical properties required of these polyurethane resins are hydrolysis resistance, light resistance, solvent resistance and the like. The polyurethane resin composition is determined by balancing these required physical properties with required prices. Have been. For example,
In the so-called general field, where the raw material of the polycarbonate intermediate having high hydrolysis resistance but excellent in hydrolysis resistance cannot be applied, in order to maintain the hydrolysis resistance, only the polyester diol intermediate is applied alone. It is difficult, and usually a polyalkylene ether glycol intermediate is used in combination, and is mixed and used according to various required physical properties.

[0006]

The higher the solvent concentration in the wet coagulation bath, the higher the performance of the film formed and the more advantageous in terms of solvent recovery after coagulation treatment. There is a strong demand for a polyurethane resin having good film-forming properties even when the content exceeds 20%. In particular, the appearance of inexpensive non-polycarbonate polyurethane resins applicable to general fields is expected.

The present invention relates to a non-polycarbonate having excellent surface smoothness, uniform porosity and good hydrolysis resistance of a film-formed sheet during wet film formation even in a coagulation bath of a solvent solution having a solvent concentration of 20% or more.
An object of the present invention is to provide a method for producing a carbonate type solution type polyurethane resin.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies on the above problems, and as a result, by specifying the molecular weight and the like of a specific polyol component, a film forming sheet for wet film formation in an aqueous solution of a high-concentration solvent is determined. It has been found that a polyurethane resin having excellent surface smoothness and the like can be obtained, and the present invention has been achieved.

That is, the present invention provides a method for producing a polyurethane resin by wet-forming a polyurethane resin in an aqueous solvent solution, preferably an aqueous solvent solution having a solvent concentration of 20% or more, wherein the polyol component has a molecular weight of 50%.
0 to 1800 polyalkylene-ether glycol per 400 moles of the polyalkylene glycol.
Molecular weight 1 obtained by reacting 600 parts of polylactone
A method for producing a polyurethane resin, characterized by using a block copolymer of 000 to 3600. Preferably, polytetramethylene ether terglycol or its copolyether terglycol is used as the polyalkylene ether terglycol. The present invention relates to a method for producing a solution-type polyurethane resin, wherein polycaprolactone is used as the polylactone. Particularly, this is a method for producing a solution-type polyurethane resin which is excellent in surface smoothness and uniform porosity of a film-formed sheet during wet film-forming in a high-concentration solvent aqueous solution and has good hydrolysis resistance.

The polyurethane resin used in the present invention is generally obtained by reacting a polyol with a polyisocyanate and, if necessary, a polyamine. As the polyol used in the present invention, a copolymer of a high molecular weight polyol (molecular weight: about 400 to about 6000) and a low molecular weight polyol (molecular weight: less than 400) is used. That is, the present invention is characterized in that a specific block copolymer of polyalkylene ether glycol and polylactone is used as a high molecular weight polyol component.

Examples of the polyalkylene ether glycol include ethylene oxide and propylene oxide (1,1).
2- and 1,3-), butylene oxide (1,2-,
One, two or more (random and / or block) addition reaction products of 2,3- and 1,4-).
In particular, a ring-opening polymer and an addition polymer of 1,4-butylene oxide (= tetrahydrofuran) alone or two or more alkylene oxides (C _{2 to} C ₄ ) containing the same are preferred.

Examples of the polylactone include one or more ring-opening polymers such as valerolactone, methylvalerolactone, ε-caprolactone, and trimethylcaprolactone. Instead of ε-caprolactone, its ring-opened product, oxycaproic acid, can be used. In particular, a ring-opening polymer or a condensation polymer of ε-caprolactone or oxycaproic acid is preferably used.

The polyalkylene ether terglyco-
The method for producing the block copolymer of toluene and polylactone is not particularly limited, but generally, the polyalkylene ether terglycol is used without solvent in the presence of a catalyst such as tetraisopropyl titanate or tetrabutyl titanate. And various lactone monomers as described above at a predetermined ratio of 150 ° C.
It can be obtained by reacting at 220 ° C.

The reason is that a polyurethane resin obtained by using a specific block copolymer of a polyalkylene ether glycol and a polylactone as a high molecular weight polyol component has a particularly high solvent concentration of the polyurethane resin (20% or more). ) It is not known whether or not the film has excellent surface smoothness and uniform porosity during wet film formation in an aqueous coagulation bath, but one of them is polyalkylene ether glycol. Block copolymers have a more uniform polymer structure when compared at the same polyalkylene ether terglycol / polylactone ratio as compared to a polyurethane resin obtained using a mere blend of polyester and polylactone. Not only is the method of removing the organic solvent uniform, but also the use of the specific block It is assumed to be attributed to better uniform.

The amount of the block copolymer of polyalkylene ether glycol and polylactone used is 100 to 30% by weight, preferably 100 to 30% by weight of the high molecular weight polyol component.
50 wt% is used. When the amount is 30 wt% or less, the effect of improving the wet film forming property is insufficient.

The polymer polyol component which can be used other than the block copolymer of the present invention includes two O
Although it preferably has an H group, it is also possible to use a limited amount of a compound having a high functionality. In this case, however, care must often be taken to include some of the monofunctional reactants so that the urethane prepolymer produced retains its thermoplasticity.

Examples of other polymer polyols include:
There are hydroxy-terminated polyesters, polycarbonates, polyester carbonates, polyethers, polyether carbonates, polyester amides, etc. Of these, polyesters, polycarbonates and polyesters are exemplified. Is preferred.

Examples of the polyester polyol include a reaction product of a divalent alcohol and a dibasic carboxylic acid. Instead of the free dicarboxylic acids, the corresponding anhydrides or diesters of lower alcohols or mixtures thereof can also be used for the preparation of the polyesters.

The divalent alcohol is not particularly limited, but ethylene glycol, 1,3- and 1,2-propylene glycol, 1,4- and 1,3- and 2,3-
Butylene glycol, 1,6-hexane glycol,
1,8-octanediol, neopentyl glycol,
Cyclohexanedimethanol, 1,4-bis- (hydroxymethyl) -cyclohexane, 2-methyl-1,3-
Propanediol, 2,2,4-trimethyl-1,3-
Pentanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, dibutylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. No.

The dibasic carboxylic acids can be aliphatic, cycloaliphatic, aromatic and / or heterocyclic and can be unsaturated or substituted, for example, by halogen atoms. These carboxylic acids include, but are not limited to,
For example, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimetic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrahydroisophthalic anhydride, hexahic anhydride Hydroisophthalic acid, endomethylene tetrahydrophthalic anhydride, glutaric anhydride,
Maleic anhydride, maleic acid, fumaric acid, dimer fatty acids such as oleic acid, dimethyl terephthalate and mixed terephthalates are mentioned.

[0021] These polyester polyols can also have a portion of the carboxy terminal groups. For example, ε-
Lactones such as caprolactone, or polyesters of hydroxycarboxylic acids such as ε-hydroxycaproic acid can also be used.

Polycarbonate having a hydroxy group
For example, 1,3-propanediol, 1,
Diols such as 4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol and / or polytetramethylene glycol and phosgene, diallyl carbonate (E.g., diphenyl carbonate) or a reaction product with a cyclic carbonate (e.g., propylene carbonate).

The polyetherpolyol includes a starting compound having a reactive hydrogen atom and, for example, ethylene oxide,
Examples include alkylene oxides such as propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, and epichlorohydrin, or reaction products with a mixture of these alkylene oxides.

Starting compounds having a reactive hydrogen atom include water, bisphenol A and polyester polyols.
And the above-mentioned divalent alcohols for producing alcohols. Examples of low molecular weight polyols include divalent alcohols used for producing the above-mentioned polyester polyols.
Le.

The polyisocyanate used in the present invention includes an organic diisocyanate represented by the formula: R (NCO) ₂ (where R is any divalent organic group).

Examples thereof include, but are not limited to, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (= isophorone diisocyanate), bis- (4-isocyanatocyclohexyl) methane (= hydrogenated) MDI), 2- and 4-
Isocyanatocyclohexyl-2'-isocyanatocyclohexylmethane, 1,3- and 1,4-bis- (isocyanatomethyl) -cyclohexane, bis- (4-isocyanato-3-methylcyclohexyl) methane, 1,3
-And 1,4-tetramethylxylidene diisocyanate-
G, 2,4- and / or 2,6-diisocyanatotoluene, 2,2'-, 2,4'- and / or 4,4'-
Diisocyanatodiphenylmethane, 1,5-naphthalenediisocyanate, p- and m-phenylene diisocyanate, dimeryl diisocyanate, xylylene diisocyanate, diphenyl-4,4'- Diisocyanate and the like.

The production conditions of the urethane polymer or urethane prepolymer are not particularly limited, but are usually from 0 to
At 120 ° C., preferably 40 to 100 ° C., in the presence of a suitable organic solvent, these urethanizing raw materials are stirred and mixed without a catalyst or using a known urethanizing catalyst or by adding a reaction retarder. can get. Further, in the case of polymerization, at or near the end point of the reaction, a compound having a monofunctional active hydrogen can be added to substantially eliminate unreacted isocyanate groups.

The NCO / OH equivalent ratio is usually 0.95 to 1.05 in the case of polymerization and 1.05 to 2.5 in the case of prepolymerization. On the other hand, in the present invention, an organic diamine is optionally used as a chain extender for the urethane prepolymer.

The organic diamine is not particularly restricted but includes, for example, diaminoethane, 1,2- or 1,3-diaminopropane, 1,2- or 1,3- or 1,4-diaminobutane, 1,5 -Diaminopentane, 1,6-diaminohexane, piperazine, N, N'-bis- (2-aminoethyl) piperazine, 1-amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane (= isophoronediamine ), Bis- (4-aminocyclohexyl) methane, bis- (4-amino-3-butylcyclohexyl) methane, 1,2-, 1,3- and 1,4-diaminocyclohexane, 1,3-diaminopropane, etc. Hydrazine, amino acid hydrazide, hydrazide of semi-carbazide carboxylic acid, bis (hydrazide) and bis (semicarbazide) It can also be used.

The conditions for the chain extension reaction using an organic diamine are not particularly limited, but the reaction is usually carried out at a temperature of 80 ° C. or lower, preferably 0 to 70 ° C., under good stirring conditions. An organic solvent is used for the production of the polyurethane resin of the present invention. However, in order to enable wet film formation, it is usually necessary to use a solvent that is soluble in water.

Examples thereof include, but are not limited to, dimethylformamide, diethylformamide, dimethylacetamide, formylmorpholine, hexamethylphosphoramide, dimethylsulfoxide and the like. These organic solvents may be used in their entirety at the beginning of the urethanization reaction, or may be partially used in the middle of the reaction.

The concentration of the polyurethane resin solution is as follows:
Although not limited, usually 15 to 40% is applied in consideration of economy and workability. The wet film forming conditions are not limited, but are usually 0 to 100 ° C., preferably room temperature to 70 ° C., using water or a mixture of water and a solvent of a polyurethane resin as a coagulating liquid. Is immersed in a coagulation liquid for a predetermined time to form a film. The higher the concentration of the solvent in the coagulation bath, the more advantageous in the recovery of the polyurethane resin solvent after the coagulation treatment, and the polyurethane resin solution obtained in the present invention has good film formation even at a high solvent concentration (more than 20%). Maintain their sexuality.

In the process for producing a polyurethane resin of the present invention, a stabilizer such as an antioxidant, a lubricant, a non-solvent, a pigment, a filler, an antistatic agent and other additives may be added at any time of the reaction, if necessary. Can be added.

[0034]

Next, embodiments of the present invention will be described with reference to specific examples, but the present invention is not limited to these examples. The parts and percentages in the examples relate to weight unless otherwise specified.

Reference Example 1 Polytetramethylene ether glycol (hereinafter referred to as PTMG)
Abbreviated as) / polycaprolactone (hereinafter abbreviated as PCL) block copolymer (hereinafter abbreviated as PTMG / PCL) -1 of a stirrer, thermometer, N ₂ inlet and air-condenser - four openings equipped with a Place the flask in the mantle heater,
In a flask, 1500 parts of PTMG (molecular weight 1500) and 1000 parts of ε-caprolactone monomer (hereinafter abbreviated as ε-CL) are charged, and N ₂ blow and stirring are started.
After the mixture was uniformly mixed, 0.075 parts of tetrabutyl titanate (based on the total charged amount of 30 ppm) was added, heating was started, and the temperature was raised to 190 ° C. After that, 19
The mantle heater was removed by holding at 0 ° C. for 7 hours, cooled by air cooling to about 80 ° C., and the product was taken out.
The OH number of the product was 44.8 (molecular weight 2504).

Reference Example 2 Production of polytetramethylene ether terglycol / polyvalerolactone (hereinafter abbreviated as PVL) block copolymer (hereinafter abbreviated as PTMG / PVL) -1 PTMG / PVL-1 was produced in exactly the same manner as in Reference Example 1 except that 1000 parts of valerolactone monomer was used instead of 1000 parts of -CL. The OH number of the product was 44.9 (molecular weight: 2499).

REFERENCE EXAMPLE 3 Polypropylene ether glycol / polycaprolactone (hereinafter abbreviated as PPG) block copolymer (hereinafter referred to as P)
Production of PG / PCL) -1 In Reference Example 1, PTMG (molecular weight 1500) 150
Instead of 0 parts, add PPG (molecular weight 1000) to 1000
PPG / P in exactly the same manner as in Reference Example 1 except that parts were charged and the amount of tetrabutyl titanate was reduced to 0.06 parts.
CL-1 was produced. The OH number of the product was 56.2 (molecular weight 1996).

[Reference Examples 4 to 13] In the same manner as in Reference Examples 1 and 3, various block copolymers comprising the polyether having the composition shown in Table 1 and the amount of CL added per mole thereof were produced. did.

Tables 1 and 2 summarize the block copolymers of Reference Examples 4 to 13.

[0040]

[Table 1]

[0041]

[Table 2] Example 1 1252 parts of PTMG / PCL block copolymer-1 obtained in Reference Example 1 and ethylene glycol 1
To 50 parts of the mixture are added 730 parts of diphenylmethane diisocyanate in 6396 parts of dimethylformamide to 70 parts.
At 10 ° C. for 10 hours to give a polyurethane solution (resin concentration 2
5.0%, viscosity 38,000 cps / 25 ° C.).

The polyurethane solution had a resin concentration of 20%.
Add dimethylformamide so that the thickness is about 1m
m was cast on a glass plate and immersed in a 50 ° C. aqueous solution containing 50% dimethylformamide for coagulation. Next, the solvent was sufficiently removed in warm water and dried in a hot air drier to obtain a porous layer sheet.

The surface of the sheet has good smoothness,
The apparent specific gravity was 0.472, and when the sheet cross section was observed, it had uniformly dispersed fine pores. Further, when the film-formed sheet was placed in a wet heat test machine at 70 ° C./95% relative humidity and taken out after 4 weeks, the surface condition showed almost no change, and the 100% modulus of the test piece cut out therefrom was It was reduced by 20% as compared with that before the wet heat test.

Example 2 PTMG obtained in Reference Example 4
/ 1302 parts of PCL-2 and ethylene glycol 15
To 7.5 parts of the mixture was added diphenylmethane diisocyanate.
760 parts in dimethylformamide 6658 parts
The mixture was reacted at 10 ° C. for 10 hours to obtain a polyurethane solution (resin concentration: 25.1%, viscosity: 34,000 cps / 25 ° C.).

When this polyurethane solution was sheeted under the same wet film forming conditions as in Example 1, the surface smoothness was good, the apparent specific gravity was 0.475, and the sheet cross section was uniform. It had dispersed fine pores.

Further, when the film-formed sheet was observed after the same wet heat test as in Example 1, the surface condition showed almost no change.
The 100% modulus of the test piece cut out therefrom was 23% lower than that before the wet heat test.

Example 3 PTMG obtained in Reference Example 1
1252 parts of / PCL block-1 and 222 parts of isophorone diisocyanate were kept in 632 parts of dimethylformamide at 70 ° C. for 4 hours to obtain an isocyanate-terminated urethane prepolymer.

Next, 3051 parts of dimethylformamide was added, and the mixture was cooled to 40 ° C. while being uniformly mixed.
A mixture of 96.6 parts of 4'-diaminodicyclohexylmethane, 6.4 parts of di-n-butylamine and 1.6 parts of methanol was added with vigorous stirring, and the temperature was raised to 50 ° C. by using heat generation. Thereafter, the temperature was further maintained for one hour. Thereafter, the temperature was raised to 70 ° C., kept at 70 ° C. for 2 hours, and then cooled to room temperature, and the polyurethane solution (resin concentration 30.0%, viscosity 2
5,000 cps / 25 ° C.).

When this polyurethane solution was sheeted under the same wet film forming conditions as in Example 1, the surface smoothness was good, the apparent specific gravity was 0.485, and the sheet cross section was uniform. It had dispersed fine pores.

Further, when the film-formed sheet was observed after the same wet heat test as in Example 1, the surface condition showed almost no change.
The 100% modulus of the cut specimen was 15% less than that before the wet heat test.

Example 4 PTMG obtained in Reference Example 2
/ 1249 parts of PVL-1 and 150 parts of ethylene glycol
Part of the mixture, diphenylmethane diisocyanate 73
0 parts was reacted in 6387 parts of dimethylformamide at 70 ° C. for 10 hours to prepare a polyurethane solution (resin concentration 25.
0%, viscosity 32,000 cps / 25 ° C.).

When this polyurethane solution was sheeted under the same wet film forming conditions as in Example 1, the surface smoothness was good, the apparent specific gravity was 0.475, and the sheet cross section was uniform. It had dispersed fine pores.

Further, when the film-formed sheet was observed after the same wet heat test as in Example 1, the surface condition showed almost no change.
The 100% modulus of the test piece cut out therefrom was 22% lower than that before the wet heat test.

Example 5 The PPG obtained in Reference Example 3
A mixture of 998 parts of PCL-1 and 112 parts of ethylene glycol was reacted with 577 parts of diphenylmethane diisocyanate in 5061 parts of dimethylformamide at 70 ° C. for 10 hours to obtain a polyurethane solution (resin concentration: 25.1%,
(Viscosity 33,000 cps / 25 ° C.).

When this polyurethane solution was sheeted under the same wet film forming conditions as in Example 1, the surface smoothness was good, the apparent specific gravity was 0.472, and the sheet cross section was uniform. It had dispersed fine pores.

Further, when the film-formed sheet was observed after the same wet heat test as in Example 1, the surface condition showed almost no change.
The 100% modulus of the test piece cut out was 25% lower than that before the wet heat test.

Example 6 Dimethylformamide was added to the polyurethane solution obtained in Example 1 so that the resin concentration was 20%, and the solution was cast on a glass plate so as to have a thickness of about 1 mm. It was immersed and coagulated in an aqueous solution at 40 ° C. containing 20% dimethylformamide. Next, the solvent was sufficiently removed in warm water and dried in a hot air drier to obtain a porous layer sheet.

The surface of the sheet has good smoothness,
The apparent specific gravity was 0.392, and when the sheet cross section was observed, it had uniformly dispersed fine pores. Furthermore,
When the film-formed sheet was observed after the wet heat test as in Example 1, the surface condition showed almost no change, and the 100% modulus of the test piece cut out therefrom was reduced by 24% as compared with that before the wet heat test. Had become.

Example 7 The polyurethane solution obtained in Example 2 was treated with 50% dimethylformamide containing 35% dimethylformamide.
A sheet was formed under the same wet film forming conditions as in Example 6 except that the solidification was carried out in an aqueous solution at a temperature of 0 ° C. The surface smoothness was good, the apparent specific gravity was 0.398, and the sheet cross section was observed. , And had uniformly dispersed fine pores.

Further, when the film-formed sheet was observed after the same wet heat test as in Example 1, the surface condition showed almost no change.
The 100% modulus of the test piece cut out was 25% lower than that before the wet heat test.

Examples 8 to 10 In the same manner as in Examples 1 to 7, various block copolymers and ethylene glycol were mixed as shown in Tables 1 and 2, and dimethylformamide was added. After uniform dissolution, a predetermined amount of diphenylmethane diisocyanate was further added, and the mixture was reacted at 70 ° C. for 10 hours to obtain a polyurethane solution as shown in Tables 3 and 4.

When these polyurethane solutions were formed into sheets under the same wet film forming conditions as in Example 1, the film-formed sheets were as shown in Tables 3 and 4, respectively. Further, when the film-formed sheet was observed after the wet heat test in the same manner as in Example 1, the sheet state was as shown in Tables 3 and 4, respectively.

[0063]

[Table 3]

[0064]

[Table 4] The M reduction rate in the table represents a 100% modulus reduction rate.
The wet film formation conditions were as follows: Comparative Example 8 was a 20% DMF aqueous solution / 4
0 ° C., Comparative Example 9 is 35% DMF aqueous solution / 50 ° C., while others are 50% DMF aqueous solution / 50 ° C.

Comparative Example 1 In Example 1, PTMG
/ PCL-1 was replaced with 1252 parts of a molecular weight of 1500
562.5 parts of PTMG and PCL37 having a molecular weight of 3000
5 parts and mixed with ethylene glycol reduced from 150 parts to 103 parts, 730 parts to 540 parts
63 parts of diphenylmethane diisocyanate
A polyurethane solution (resin concentration: 25.0%, viscosity: 37,00) was reacted in dimethylformamide reduced from 96 parts to 4741 parts under exactly the same reaction conditions as in Example 1.
0 cps / 25 ° C.).

When this polyurethane solution was sheeted under the same wet film forming conditions as in Example 1, the surface became an uneven surface with fine cracks, and the apparent specific gravity became 0.528.
The cross section of the sheet was mixed with non-uniform large and small pores.

[Comparative Example 2] PTMG obtained in Reference Example 8
1294 parts of / PCL-6 and ethylene glycol 16
To 5.6 parts of the mixture was added diphenylmethane diisocyanate.
760 parts in 6659 parts of dimethylformamide.
At 10 ° C. for 10 hours to give a polyurethane solution (resin concentration 2
4.8%, viscosity 31,000 cps / 25 ° C.).

When this polyurethane solution was sheeted under the same wet film forming conditions as in Example 1, the surface was partially smooth, but mostly had wrinkled irregularities. Was 0.510, and although micropores were partially observed in the sheet cross section, pores of non-uniform size were mostly generated.

[Comparative Example 3] PTMG obtained in Reference Example 9
/ PCL-7 with 1297 parts and ethylene glycol 162
Parts of the mixture, diphenylmethane diisocyanate 76
0 parts in dimethylformamide 6657 parts at 70 ° C. for 10 hours to give a polyurethane solution (resin concentration 25.
1%, viscosity 32,500 cps / 25 ° C.).

When this polyurethane solution was sheeted under the same wet film forming conditions as in Example 1, the surface was partially smooth, but mostly had wrinkle-like uneven surfaces. The specific gravity was 0.520, and although fine pores were partially observed in the sheet cross section, pores of non-uniform size were mostly generated.

[Comparative Example 4] PTM obtained in Reference Example 10
1292 parts of G / PCL-8 and ethylene glycol 16
To 8.3 parts of the mixture was added diphenylmethane diisocyanate
760 parts in 6661 parts of dimethylformamide.
At 10 ° C. for 10 hours to give a polyurethane solution (resin concentration 2
4.9%, viscosity 33,500 cps / 25 ° C.).

When this polyurethane solution was sheeted under the same wet film forming conditions as in Example 1, the surface was smooth in part, but was mostly wrinkled. ,
The apparent specific gravity was 0.518, and although fine pores were partially observed on the sheet cross section, most of the pores had an uneven size.

Comparative Examples 5 to 9 In the same manner as in Comparative Examples 2 to 4, as shown in Tables 3 and 4, various block copolymers and ethylene glycol were mixed, and dimethylformamide was added. Then, a predetermined amount of diphenylmethane diisocyanate was added, and the mixture was reacted at 70 ° C. for 10 hours to obtain a polyurethane solution as shown in Tables 3 and 4.

These polyurethane solutions were used in Comparative Examples 5 to 7
In Comparative Examples 8 and 9, which were formed into sheets under the same wet film forming conditions as in Examples 6 and 7, respectively, they were in the same film-forming sheet state as shown in Tables 3 and 4.

The wet heat test of the film-formed sheet was not performed due to the poor sheet condition.

[0076]

The polyurethane resin obtained by the present invention can be used even in an aqueous solution coagulation bath having a high polyurethane resin solvent concentration (more than 20%), which was difficult with conventional products. -It has excellent surface smoothness and uniform porosity, and is advantageous for solvent recovery after coagulation treatment.
Its hydrolysis resistance is also good. From these facts, the polyurethane resin obtained by the present invention is particularly suitable for non-polycarbonate wet porous layer applications.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 18/00-18/87 D06N 3/14

Claims (4)

(57) [Claims] 1. A method for producing a polyurethane resin by wet-forming a film of the polyurethane resin in an aqueous solution of a solvent, wherein the polyol component has a molecular weight of 500 to 180.
0 to 400 to 2 per mol of the polyalkylene-ether glycol.
Molecular weight 1 obtained by reacting 600 parts of polylactone
A method for producing a polyurethane resin, comprising using a block copolymer of 000 to 3600. 2. The method for producing a polyurethane resin according to claim 1, wherein polytetramethylene ether glycol is used as the polyalkylene ether glycol. 3. The method for producing a polyurethane resin according to claim 1, wherein polycaprolactone is used as the polylactone. 4. The method for producing a polyurethane resin according to claim 1, wherein the solvent concentration of the aqueous solvent solution is 20% or more.