JPH0370724A - Polyurethane resin - Google Patents

Abstract

PURPOSE:To obtain a polyurethane resin excellent in dissolution resistance to fluorocarbons by adding a lactone and alkylene oxide in a specific proportion to a specific alcohol, etc., and reacting the resultant polyoxyalkylene polyol with a polyisocyanate. CONSTITUTION:A lactone (e.g. beta-propiolactone) in an amount of 0.125-1.0mol based on hydroxyl groups of an alcohol (e.g. glycerol) having 3-6mol hydroxyl groups and 1.0-3.0mol alkylene oxide (e.g. ethylene oxide) are added to the aforementioned alcohol having the hydroxyl groups or a polyoxyalkylene polyol preferably using an amine catalyst expressed by formula I or II (R1 is H, 1-6C alkyl, etc.; R2 is 1-6C alkyl, etc.) and/or an alkali hydroxide catalyst and the resultant polyoxyalkylene polyol is preferably mixed and reacted with a polyisocyanate (preferably phenylene diisocyanate, etc.) to afford a polyurethane resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel polyurethane resin having excellent resistance to fluorocarbon dissolution.

More specifically, HCFC-123 and HCF, which are hydrochlorofluorocarbons (hereinafter abbreviated as HCFC)
This invention relates to a new polyurethane resin that is resistant to melting against C-14lb.

[Prior Art] Traditionally, when producing urethane foam, fluorocarbons, especially chlorofluorocarbons (hereinafter referred to as CFCs), have been used as a foaming means.
CFC-11 and CFC-12 (abbreviated as "CFC-11" and "CFC-12") are used, but these have been cited as substances that decompose the ozone layer and promote the greenhouse effect, and recently their production and use have been regulated. There is. Therefore, as a blowing agent, C
HCFC-123 and HCFC-1 have a shorter lifetime in the atmosphere than FC-II and CFC-12 and decompose quickly.
41b has been attracting attention as an alternative. However, these fluorocarbons have strong resin-dissolving power and tend to deteriorate the physical properties of urethane foam. In particular, for products that require insulation, such as electric refrigerators, it has become necessary to improve the urethane resin because it dissolves the closed cells in the urethane foam, significantly reducing its insulation effect.

[Problems to be Solved by the Invention] The purpose of the present invention is to use HCFC-123 and HCFC-1, which have strong resin-dissolving power, as a blowing agent during the production of rigid urethane foam.
The object of the present invention is to provide a novel hard urethane resin with excellent resistance to fluorocarbon dissolution, such that the foam properties are the same as those of conventional materials even when 141b is used.

[Means to solve the problem]

In order to achieve the above object, the present inventors made extensive studies and finally arrived at the present invention.

That is, the present invention provides an alcohol or polyoxyalkylene polyol (a
) obtained by mixing and reacting polyoxyalkylene polyol (A) with 0.125 to 1.0 mol of lactone and 1.0 to 3.0 mol of alkylene oxide added per hydroxyl group and polyisocyanate. It is a polyurethane resin characterized by:

The polyhydric alcohol or polyoxyalkylene polyol (a) used in the present invention has 3 to 8 moles of hydroxyl groups per molecule, and this hydroxyl group and lactone react to form an ester bond, and further alkylene By reacting the oxides, a polyoxyalkylene polyol (A) having an ester skeleton can be synthesized.

Polyhydric alcohols used in the present invention include glycerin, l-limethylolpropane, 1,2.6-hexandriol, triethanolamine, pentaerythritol, tetramethylolcyclohexane, methylglucoside, 2,2,6.6- Examples of the polyoxyalkylene polyol (a) include tetrakis(hydroxyl)cyclohexanol, sorbitol, mannitol, and dulcilitol. It is also possible to use more than one species in combination.

Lactones used in the present invention include β-propiolactone, T-butyrolactone, δ-valerolactone, ε-
Examples include caprolactone.

Examples of the alkylene oxide used in the present invention include ethylene oxide, propylene oxide, butylene oxide, etc., and these may be used alone or two or more types may be used simultaneously.

The polyoxyalkylene polyol (A) used in the present invention is a polyhydric alcohol or polyoxyalkylene polyol (A) having 3 to 8 moles of hydroxyl groups per molecule.
0.125 to 1.0 mol of lactone and 1.0 to 3.0 mol of alkylene oxide are added per hydroxyl group of a).

When the number of hydroxyl groups per molecule is less than 3 moles, the strength of the resin tends to become brittle when made into a polyurethane resin. On the other hand, if the number of hydroxyl groups per molecule exceeds 8 moles, the number of ester bonds per molecule increases, and as a result, the viscosity of the polyoxyalkylene polyol (A) becomes high, making it difficult to handle and resulting in poor workability.

If less than 0.125 mol of lactone is reacted per hydroxyl group, the solubility resistance to HCFC will be lost, whereas if it exceeds 1.0 mol, unreacted lactone will remain, so it can be obtained by reacting with polyisocyanate. Polyurethane resin becomes brittle.

If less than 1.0 alkylene oxide is reacted per water fli, the mixing and dispersibility with isocyanate will be poor and it will be impossible to produce the desired polyurethane resin. Moreover, if it exceeds 3.0, the dissolution resistance to HCFC will be lost.

In the present invention, the catalyst used for adding lactone and alkylene oxide to the hydroxyl group of polyhydric alcohol or polyoxyalkylene polyol (a) is:
The amine compound is an amine compound represented by the following general formula (L) or (2).

NR, R, R1... (1) R+ Rt N (CHt)n NR+ Rz
・・・(2) (In the above formula, R1 is an alkyl group from +1.C1 to C1 and CHtCLOII, CLCH(C1
h) OH, R2 represents an alkyl group from CI to C4 and C11ICLOLCLCH(CL)011;

Moreover, n is an integer of 1-6. ) Examples of amine compounds include diptylamine, ethylene cyanide, tetramethylenediamine, monoethanolamine, jetanolamine, triethanolamine,
isopropanolamine, triethylamine, tri-n
-propylamine, di-n-propylamine, n-propylamine, n-amylamine, N,N-dimethylethanolamine, isobutylamine, isoamylamine, methyldiethylamine, and the like.

Further, examples of the alkali hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, and the like. Each of the above catalysts can be used alone or in combination of two or more.

The polyisocyanates used in the present invention include phenyl diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate, polymethylene polyphenyl polyisocyanate (MDI-CR'), etc. Those used in can be used alone or in combination of two or more.

When reacting polyoxyalkylene polyol (A) and polyisocyanate, the equivalent ratio between the two (number of hydroxyl groups in polyoxyalkylene polyol (A)/number of polyisocyanate groups) is preferably 0.9 to 1.2.

If the equivalence ratio between polyoxyalkylene polyol (A) and polyisocyanate is less than 0.9, unreacted polyisocyanate will remain. Also, the equivalence ratio is 1.2
On the other hand, if it exceeds this range, a large amount of unreacted polyoxyalkylene polyol will remain, so the above range is preferable.

Polyoxyalkylene polyol (A) used in the present invention
The manufacturing method is to charge polyhydric alcohol or polyoxyalkylene polyol (a), lactone and catalyst in an autoclave and react, then gradually add alkylene oxide and react.The reaction temperature is 90°C.
~130°C is preferred.

If the reaction temperature is less than 90°C, the reaction will not proceed, and
When the temperature exceeds 130°C, side reactions occur, which is not preferable.

〔Example〕

The present invention will be explained below with reference to Examples.

The hydroxyl value (OH value) and viscosity were measured in accordance with JIS 1557. In addition, the fluorocarbon absorption rate is 100 fluorocarbons.
The cured product was immersed in water, and the weight increase after 24 hours was measured.

Example 1 Polyoxyalkylene polyol (a) having a number average molecular weight (hereinafter abbreviated as Mn) of 150 and an average number of functional groups (hereinafter abbreviated as f) of 3.0 (Mitsui Toatsu Chemical ■ brand name MN-150)
731 g and 419 g of T-butyrolactone were charged into a No. 21 autoclave, and the autoclave was purged with nitrogen and then heated to 120°C. Add and mix 7174.3 g of triethyl, and further,
282 g of propylene oxide was gradually charged.

After reacting for 3 hours, propylene oxide in the system was removed. OH number 532+wgKOH/g, viscosity 1700c
p/25°C polyoxyalkylene polyol (A-
1) 1417g was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． 00g and MDI-CR (MD I manufactured by Mitsui Toatsu Chemical Co., Ltd.)
-CR200) 15.50g and Kaolizer No.

A cured product of polyurethane resin was prepared by mixing 0.12 g of 1 (manufactured by Kao) and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

Example 2 Mn150, f3. o polyoxyalkylene polyol (a) (Mitsui Toatsu Chemical ■product brand MN-150) 53
1 g and 304 g of T-butyrolactone were charged into a No. 22 autoclave, and after purging with nitrogen, the temperature was raised to 120°C.

7574.4 g of triethyl was added and mixed, and further, 616 g of propylene oxide was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed. OH
Polyoxyalkylene polyol (A-2) 1420 with a value of 406 mgKOH/g and a viscosity of 810 cp/25°C
I got g.

Obtained polyoxyalkylene polyol (A) 12
．． 00g and MDI-CR (MD I manufactured by Mitsui Toatsu Chemical Co., Ltd.)
-CR200) 11.83g and Kaolizer No.

A cured product of polyurethane resin was prepared by mixing 0.12 g of 1 (manufactured by Kao FSJ) and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1 in the same manner as in Example 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

Example 3 Mn150, f3. o polyoxyalkylene polyol (a) (Mitsui Toatsu Chemical ■product brand MN-150) 37
6 g and 215 g of T-butyrolactone were charged into an autoclave No. 21, and after purging with nitrogen, the temperature was raised to 120°C.

7472.2 g of triethyl and 2.2 g of potassium hydroxide
g was added and mixed, and further 872 g of propylene oxide was added.
was gradually introduced. After reacting for 3 hours, propylene oxide in the system was removed, neutralized with acetic acid, and filtered under reduced pressure. OH number 273+igKOR/g, viscosity 1
20cp/25℃ polyoxyalkylene polyol (
A-3) 1444g was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． OOg and MDI-CR (Mitsui Toatsu Chemical ■ MD [-
CR200) 7.95g and Kaolizer No.

A cured product of polyurethane resin was prepared by mixing 0.12 g of 1 (manufactured by Kao ■) and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1 in the same manner as in Example 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

Example 4 Polyoxyalkylene polyol (a) with M n 150, f 3.0 (Mitsui Toatsu Chemicals brand name MN-150) 2
81g and 483g of T-butyrolactone in 21! After the autoclave was purged with nitrogen, the temperature was raised to 120°C.

Triethyl alcohol 2. Ig and potassium hydroxide2.
Add and mix 1g of propylene oxide 652
g was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed, neutralized with acetic acid, and filtered under reduced pressure. 1401 g of polyoxyalkylene polyol (A-4) having an OH value of 231 mg KO) I/g and a viscosity of 18500 cp/25°C was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． OOg and MDI-CR (MD I manufactured by Mitsui Toatsu Chemical Co., Ltd.)
-CR200) 6.73g and Kaolizer No.

1 (manufactured by Kao ■) 0.12. A cured polyurethane resin was prepared by mixing and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1 in the same manner as in Example 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

Example 5 526 g of triethanolamine and 304 g of T-butyrolactone were charged into a 22 autoclave, and after purging with nitrogen, the temperature was raised to 120°C. 7574.4 g of triethyl was added and mixed, and further, 614 g of propylene oxide was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed. OH number 421 gKOH/g, viscosity 1
1431 g of polyoxyalkylene polyol (A-5) of 8100 cp/25°C was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． OOg and MD I-CR (MD manufactured by Mitsui Toatsu Ka1!
I-CR200) 12.26g and Kaolizer N. .

A cured product of polyurethane resin was prepared by mixing 0.12 g of 1 (manufactured by Kao ■) and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1 in the same manner as in Example 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

Example 6 Polyoxyalkylene polyol (a) with M n 472 and r6.0 (Mitsui Toatsu Chemical @) brand name So-470)
1,124 g and 205 g of T-butyrolactone were placed in a No. 21 autoclave, and after purging with nitrogen, the temperature was raised to 120°C. 4.4 g of triethylamine was added and mixed, and then 138 g of propylene oxide was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed. O
H number 540mgKOH/g, viscosity 20500cp/25
Polyoxyalkylene polyol (A-6) 145 °C
2g was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． 00g and MDI-CR (MD I manufactured by Mitsui Toatsu Chemical Co., Ltd.)
-CR200) 15.73g and Canalizer No.

A cured product of polyurethane resin was created by mixing 0.12 g of 1 (manufactured by Kao ■) and reacting at room temperature.The obtained polyurethane resin was immersed in the Freon shown in Table 1 in the same manner as in Example 1, The Freon absorption rate was measured after 24 hours. The results are shown in Table 1.

Example 7 Mn730, f8.0 polyoxyalkylene polyol (a) (Mitsui Toatsu Chemicals brand SU-730) 12
33 g and 145 g of γ-butyrolactone were placed in a No. 21 autoclave, and after purging with nitrogen, the temperature was raised to 1207C.

4.4 g of dimethylethanolamine was added and mixed, and further, 98 g of propylene oxide was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed. OH value 507mgKO■/g, viscosity 19700cp/
Polyoxyalkylene polyol (A-7) at 25°C
) 1455g was obtained.

Obtained polyoxyalkylene polyol (A)! 2
．． OOg! :MD I-CR (M made by Mitsui Toatsu Chemical Co., Ltd.)
DI-CR200) 14.77g and Canalizer No.

A cured product of polyurethane resin was prepared by mixing 0.12 g of 1 (manufactured by Kao ■) and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1 in the same manner as in Example 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

Example 8 Polyoxyalkylene polyol (a) with M n 730 and r 8.0 (Mitsui Toatsu Chemical brand 5tl-730)
804 and 379 g of T-butyrolactone were charged into an autoclave No. 21, and after replacing with nitrogen and N, the temperature was raised to 120''C.

2.2 g of triethylamine and 2.2 g of potassium hydroxide
Add and mix 256 g of propylene oxide.
was gradually introduced. After reacting for 3 hours, propylene oxide in the system was removed, neutralized with acetic acid, and filtered under reduced pressure. OH value 337 sogKO! (7g, viscosity 3
1410 g of polyoxyalkylene polyol (A-8) of 4700 cp/25°C was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． OOg and MDI-CR (MD I manufactured by Mitsui Toatsu Chemical Co., Ltd.)
-CR200) 9.82g and Canalizer No.

A cured product of polyurethane resin was prepared by mixing 0.12 g of 1 (manufactured by Kao ■) and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1 in the same manner as in Example 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

Example 9 Polyoxyalkylene polyol (a) with Mn 150 and f 3.0 (Mitsui Toatsu Chemical Co., Ltd. brand name 1'IIN-150)
) 632 and 480 g of ε-caprolactone were charged into an autoclave No. 21, and the autoclave was purged with nitrogen and then heated to 120°C.

7174.1 g of triethyl was added and mixed, and further, 244 g of propylene oxide was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed. OH
Polyoxyalkylene polyol (A-9) 1349 with a value of 511 mg 10R/g and a viscosity of 9900 cp/25°C
I got g.

Obtained polyoxyalkylene polyol (A) 12
．． 00g and MDI-CR (MD I manufactured by Mitsui Toatsu Chemical Co., Ltd.)
-CR200) 14.88g and Canalizer No.

A cured product of polyurethane resin was prepared by mixing 0.12 g of 1 (manufactured by Kao ■) and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1 in the same manner as in Example 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

Example 10 Polyoxyalkylene polyol (a) with M n 150.13.0 (Mitsui Toatsu Chemical Company name MN-150) 7
65 g and 439 g of γ-butyrolactone were charged into a No. 21 autoclave, and after reducing the pressure, the temperature was raised to 120°C. 4.3 g of triethylamine was added and mixed, and further, 224 g of ethylene oxide was gradually charged. After reacting for 3 hours, ethylene oxide in the system was removed.

OH number 589mgKON/g, viscosity 1100cp/25
Polyoxyalkylene polyol (A-10) in °C
1418g was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． OOg and MDI-CR (MD I manufactured by Mitsui Toatsu Chemical Co., Ltd.)
-CR200) 17.16g and Canalizer No.

A cured product of polyurethane resin was prepared by mixing 0.12 g of 1 (manufactured by Kao ■) and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1 in the same manner as in Example 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

Comparative Example I M n 150, f3.0 polyoxyalkylene polyol (a) (Mitsui Toatsu Chemical ■ Brand? IIN-150
) 806 and 462 g of γ-butyrolactone were charged into an autoclave No. 21, and after purging with nitrogen, the temperature was raised to 120°C.

4.3 g of triethylamine was added and mixed, and then 155 g of propylene oxide was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed. OH
Value 622mgKOH/g, viscosity 2200cp/25”C
Polyoxyalkylene polyol (A-11) 14
10g was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． OOg and MDI-CR (Mitsui Toatsu Chemical @1!MDI
-CR200) 18.12g and Canalizer No.
.

1 (manufactured by Kao ■) was mixed and reacted, but the desired cured product was not obtained.

Comparative Example 2 Polyoxyalkylene polyol (a) with Mn 150.13.0 (Mitsui Toatsu Chemicals brand name MN-150) 443
g and 762 g of γ-butyrolactone were charged into a 2j2 autoclave, and the temperature was raised to 120° C. after replacing the autoclave with nitrogen.

4.1 g of triethylamine was added and mixed, and then 171 g of propylene oxide was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed. OH
Value 357+mgKOH/g, viscosity 7500cp/25'
C polyoxyalkylene polyol (A-12) 1
352g was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． 00g and MDI-CR (MD I manufactured by Mitsui Toatsu Chemical Co., Ltd.)
-CR200) IO, 40g and canalizer No.

0.12 g of (manufactured by Kao ■) was mixed and reacted, but the desired cured product was not obtained.

Comparative Example 3 Polyoxyalkylene polyol (a) with M n 150 and r 3.0 (Mitsui Toatsu Chemicals brand name MN-150) 1
032 g and 59 g of γ-butyrolactone were placed in a No. 21 autoclave, and after purging with nitrogen, the temperature was raised to 120°C.

6.6 g of triethylamine was added and mixed, and further, 399 g of propylene oxide was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed. OH
Value 756mgK011/g, viscosity 1030cp/25'
C polyoxyalkylene polyol (A-13) 1
460g was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． OOg and MDI-CR (MD r manufactured by Mitsui Toatsu Chemical Co., Ltd.)
-CR200) 22.02g and Canalizer No.

A cured product of polyurethane resin was prepared by mixing 0.12 g of 1 (manufactured by Kao ■) and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1 in the same manner as in Example 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

Comparative Example 4 Polyoxyalkylene polyol (a) with M n 150 and f 3.0 (Mitsui Toatsu Chemicals brand name MN-150) 2
62 g and 150 g of γ-butyrolactone were placed in a No. 21 autoclave, and after purging with nitrogen, the temperature was raised to 120°C.

2.2 g of triethylamine and 2.2 g of potassium hydroxide
Add and mix propylene oxide 1063 g.
g was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed, neutralized with acetic acid, and filtered under reduced pressure. 1468 g of polyoxyalkylene polyol (A-14) having an OH value of 202 mg K011/g and a viscosity of 540 cp/25°C was obtained.

Obtained polyoxyalkylene polyol (A) 12
．． OOg and MDI-CR (MD I manufactured by Mitsui Toatsu Chemical Co., Ltd.)
-CR200) 5.88g and Kaolizer No.

A cured product of polyurethane resin was prepared by mixing 0.12 g of (manufactured by Kao ■) and reacting at room temperature.

The obtained polyurethane resins were immersed in the fluorocarbons shown in Table 1 in the same manner as in Example 1, and the fluorocarbon absorption rate was measured after 24 hours. The results are shown in Table 1.

〔Effect of the invention〕

- Polyhydric alcohols or polyoxyalkylene polyols used in hard urethane foams (
A polyurethane resin produced from a polyoxyalkylene polyol (A) obtained by reacting a lactone and an alkylene oxide with a polyisocyanate exhibited excellent dissolution resistance to fluorocarbons.

Claims (1)

[Scope of Claims] 0.125 to 1.0 mol of lactone and 1.0 to 3 mol of alkylene oxide per hydroxyl group of alcohol or polyoxyalkylene polyol (a) having 3 to 8 mol of hydroxyl groups per molecule. A polyurethane resin characterized in that it is obtained by mixing and reacting a polyoxyalkylene polyol (A) added with .0 mole and a polyisocyanate. 2. Claim 1, wherein the polyoxyalkylene polyol (A) is obtained by reaction using an amine catalyst and/or an alkali hydroxide catalyst represented by the general formula (1) or (2).
Polyurethane resin as described. NR_1R_1R_2...(1) R_1R_2N(CH_2)NR_1R_2...(2)
(In the above formula, R_1 is H, an alkyl group from C_1 to C_6, and CH_2CH_2OH, CH_2CH(CH_3
)OH, R_2 is an alkyl group from C_1 to C_6 and CH_2CH_2OH, CH_2CH (CH_
3) Indicates OH. Moreover, n is 1-6. ) 3. When reacting polyoxyalkylene polyol (A) and polyisocyanate, the equivalent ratio of both (number of hydroxyl groups in polyoxyalkylene polyol (A)/number of polyisocyanate groups) is 0.9 to 1.2. The polyurethane resin according to claim 1, characterized in that: 4. A claim characterized in that the polyisocyanate is composed of one or more compounds selected from the group consisting of phenyl diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and polymethylene polyphenyl polyisocyanate. The polyurethane resin according to item 1.