JP2001342237A - Method of producing rigid foam synthetic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing rigid foam synthetic resin that shows excellent storage stability, when the raw materials are stored, and gives the open-cell cellular synthetic resin of high dimensional stability. SOLUTION: The polyol mixture of >=380 average hydroxyl value comprising (A) 5-25 mass % of the polyol that has <=5 mass % of the EO content, <=15 mass % of the primary hydroxyl in the whole hydroxyl, >=2 average number of functional groups and 20-120 average hydroxyl group value, (B) 40-80 mass % of the nitrogen-containing polyol that is formed with a nitrogen atom- including polymerization initiator and has >=3 average number of functional groups and 300-850 average hydroxyl group value and (C) 5-30 mass % of the polyol having >=2-3 average number of functional groups and 300-1,500 average hydroxyl group value, is reacted with a polyisocyanate in the presence of 6-14 mass %, based on the 100 mass %, of an aqueous foaming agent, a foam stabilizer and a catalyst whereby the objective rigid foam synthetic resin is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a rigid foamed synthetic resin such as a rigid polyurethane foam,
The present invention relates to the production of a hard foamed synthetic resin characterized by using a large amount of water as a foaming agent.

[0002]

2. Description of the Related Art It is widely practiced to produce a rigid foamed synthetic resin by reacting a hydroxyl compound and a polyisocyanate compound in the presence of a catalyst or the like. As the hydroxyl compound, a polyhydroxy compound is mainly used. Examples of the obtained rigid foamed synthetic resin include rigid urethane foam and rigid polyisocyanurate foam. The state of the cells of the hard foam synthetic resin includes closed cells and open cells. The closed-cell foam has closed cells, each of which is closed, and can be filled with a blowing agent having a low thermal conductivity such as halogenated hydrocarbons, and has excellent heat insulating performance. In the open-cell foam, individual cells are connected and have air permeability. For this reason, the open-cell foam has low heat insulating performance but is excellent in dimensional stability under severe temperature conditions. These foams are properly used depending on the application. However, since it is difficult to stably produce an open-cell foam, a closed-cell foam is more common.

On the other hand, various compounds are known as a foaming agent for producing a foamed synthetic resin, and HCFC-141b, which is one kind of chlorinated fluorinated hydrocarbon, is mainly used.
Is used. Some of the chlorinated fluorinated hydrocarbons used as a blowing agent may leak into the atmosphere and cause ozone depletion, so it is proposed to use more water as a blowing agent as an alternative. Have been.
Water has been used as an important secondary blowing agent in rigid polyurethane foams, but HCFC-1 has been used as a main blowing agent in rigid polyurethane foams.
It was difficult to use 41b at a high ratio that could replace it.

[0004] A foamed synthetic resin using a large amount of water has a problem that the synthetic resin becomes brittle because the ratio of urea bonds generated by the reaction between water and isocyanate increases. Even if the rigid foamed synthetic resin containing a large amount of water has good initial performance, it has a problem that it is gradually deformed when left at room temperature for a long time. Therefore, it is conceivable to use an open-cell foam synthetic resin in applications where thermal insulation performance is not important.

[0005] As a method for producing an open-celled hard foamed synthetic resin, a short-chain polyol is mixed with a long-chain polyol, a special silicone foam stabilizer is used, or a hydrophobic hydroxyl compound is mixed. There is a way to do that. However, in the method described in JP-A-06-25975 in which a long-chain polyol is mixed with a short-chain polyol, a long-chain polyol is used in an amount of 30% by mass or more in order to form open cells. have. Further, when a special silicone foam stabilizer or a hydroxy compound having a hydrophobic property is mixed and used, there is a problem that the mixed raw material becomes cloudy and easily separated, so that the prepared raw material cannot be stably stored. Also, when trying to make open cell hard foam synthetic resin by using a lot of water as a foaming agent, the balance between the foaming reaction and the resinification reaction is out of order, the foaming state becomes unstable, and foam breakage and collapse easily occur, There are drawbacks such as the failure to obtain a good open-cell foam synthetic resin. If a large amount of a catalyst or a foam stabilizer is used to prevent this, closed cells are formed and it is difficult to stably obtain an open-cell foam synthetic resin. Generalization of open-cell synthetic resin also requires means for solving these problems.

[0006]

The present invention has excellent storage stability without using a special silicone foam stabilizer or a hydrophobic hydroxyl compound in a raw material liquid, and uses a large amount of water as a foaming agent. Even if the open-celled foamed synthetic resin does not collapse, the obtained open-celled foamed synthetic resin has excellent dimensional stability, and a method for producing a hard foamed synthetic resin capable of easily obtaining an open-celled foam. The purpose is to provide.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it has been found that the above-mentioned problems can be solved by using a specific polyol mixture, thereby completing the present invention. Was. That is, the present invention is a polyol and a polyisocyanate compound blowing agent,
In the method for producing a rigid foamed synthetic resin by reacting in the presence of a foam stabilizer and a catalyst, (A)
Content of structural units based on ethylene oxide in the molecule is 5% by mass or less, primary hydroxyl groups are 15% or less of all hydroxyl groups,
The average number of functional groups is 2 or more, and the average hydroxyl value is 20 to 120 m
gKOH / g of a polyol containing 5 to 25% by mass, (B) a nitrogen-containing polyol produced by an initiator containing a nitrogen atom, having an average number of functional groups of 3 or more, and an average hydroxyl value of 300 to 850 mgKOH / g; And (C) the average number of functional groups is 2-3 and the average hydroxyl value is 300-1500 mg.
A polyol mixture composed of 5 to 30% by mass of a KOH / g polyol and having an average hydroxyl value of 380 mgKOH / g or more is used.
Provided is a method for producing an open-cell, rigid foam synthetic resin, characterized in that 6 to 14 parts by mass is used per 0 parts by mass.

Further, the present invention provides the method for producing a rigid foamed synthetic resin, wherein the polyol (A) is at least one selected from water, glycerin, trimethylolpropane, diglycerin, pentaerythritol, sorbitol and sucrose. Disclosed is a method for producing a rigid foam synthetic resin which is a polyether polyol obtained by reacting an alkylene oxide with an agent. Further, the present invention provides the method for producing a rigid foamed synthetic resin, wherein the nitrogen-containing polyol (B) is at least one selected from polyamines, alkanolamines, and Mannich reaction products of phenols, alkanolamines and aldehydes. Provided is a method for producing a rigid foam synthetic resin which is a polyether polyol obtained by reacting an initiator with an alkylene oxide.

Further, the present invention provides the method for producing a rigid foamed synthetic resin, wherein the polyol (C) is ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, trimethylolpropane, or at least one selected from them.
Disclosed is a method for producing a rigid foam synthetic resin which is a polyether polyol obtained by reacting an alkylene oxide with at least one kind of polyhydric alcohol or at least one kind selected from the polyhydric alcohol and water. further,
The present invention relates to the method for producing a rigid foam synthetic resin,
Provided is a method for producing a rigid foamed synthetic resin in which the closed cell ratio of the foamed synthetic resin is 50% or less.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is characterized in that a polyol mixture containing a polyol (A), a nitrogen-containing polyol (B) and a polyol (C) in a specific ratio is used as the polyol. Polyol (A),
As (B) and (C), polyhydric alcohols, polyether polyols, polyester polyols, hydroxyl group-containing diene polymers and the like can be used. As the polyether polyol, a polyether polyol obtained by adding at least one selected from a cyclic ether, particularly propylene oxide, ethylene oxide, and butylene oxide, to a polyhydric alcohol, a saccharide, an alkanolamine, or another initiator is preferable. Further, a polyol composition in which fine particles of a vinyl polymer are dispersed in a polyol mainly containing a polyether polyol called a polymer polyol can also be used.

[0011] Polyester polyols include polyhydric alcohols, polyhydric carboxylic acid condensed polyols and cyclic ester ring-opening polymer type polyols. Polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and the like.
Examples include glycerin, trimethylolpropane, pentaerythritol, diethanolamine, triethanolamine and the like. In the present invention, it is particularly preferable to use a polyhydric alcohol or a polyether polyol as the polyol (A), the nitrogen-containing polyol (B) and the polyol (C). Each of the polyol (A), the nitrogen-containing polyol (B) and the polyol (C) may be a single polyol or a mixture of two or more polyols produced separately.

The polyol (A) has a content of a structural unit based on ethylene oxide in the molecule of 5% by mass or less,
Primary hydroxyl groups are 15% or less of all hydroxyl groups, and the average number of functional groups is 2
As described above, the polyol has an average hydroxyl value of 20 to 120 mgKOH / g. Preferred polyols (A) include water, glycerin, and trimethylol in which the content of the constituent units based on ethylene oxide in the molecule is 5% by mass or less, the primary hydroxyl group is 15% or less of all the hydroxyl groups, the average number of functional groups is 2 or more, and Examples thereof include polyether polyols having an average hydroxyl value of 20 to 120 mgKOH / g obtained by reacting at least one initiator selected from propane, diglycerin, pentaerythritol, sorbitol and sucrose with an alkylene oxide. In the polyol (A), the content of the structural unit based on ethylene oxide in the molecule is 5% by mass or less, and preferably 2% by mass or less. If it exceeds 5% by mass, the activity is high and it is difficult to form open cells. In the present invention, the content ratio of the structural unit based on ethylene oxide indicates the mass% of the structural unit based on ethylene oxide with respect to the total mass of the polyol including the initiator. Furthermore, in the polyol (A), the primary hydroxyl groups in the molecule are 15% or less of the total hydroxyl groups, and preferably 5% or less. If it exceeds 15%, the activity becomes high and the cells become closed cells. The average hydroxyl value of the polyol (A) is 1
If it exceeds 20 mgKOH / g, it becomes difficult to form open cells. The average hydroxyl value of the polyol (A) is 25 to 25.
100 mgKOH / g is preferred, and 30 to 80 mgKO
H / g is particularly preferred. A more preferred range of the average number of functional groups is 2 to 6.

The content ratio of the polyol (A) in the polyol mixture is 5 to 25% by mass based on the total amount of the polyols (A), (B) and (C). 25
When used in excess of mass%, the cells are likely to be roughened, and the strength of the open-cell foam synthetic resin is extremely reduced. The content of the polyol (A) is preferably from 10 to 25% by mass,
Particularly preferred is 15 to 25% by mass. The nitrogen-containing polyol (B) is produced by an initiator containing a nitrogen atom, has an average number of functional groups of 3 or more, and has an average hydroxyl value of 300 to 850 mgK.
OH / g nitrogen-containing polyol. Preferred examples of the nitrogen-containing initiator used for producing the suitable nitrogen-containing polyol (B) include polyamines, alkanolamines, and Mannich reaction products of phenols, alkanolamines and aldehydes, and the like. Can be
The polyamine preferably has 2 to 5 amino groups in one molecule, and particularly preferably 2 to 3 amino groups. Specific examples thereof include ethylenediamine and tolylenediamine. Further, the alkanolamine preferably has a total of 2 to 5 amino groups and hydroxyl groups in one molecule,
Those having 3 to 5 are particularly preferred. Specific examples thereof include monoethanolamine, diethanolamine, and triethanolamine. Specific examples of Mannich reaction products of phenols, alkanolamines and aldehydes include nonylphenol, monoethanolamine, and reaction products of formaldehyde.

As the nitrogen-containing polyol (B), the average number of functional groups obtained by reacting an alkylene oxide with an initiator containing a nitrogen atom is 3 or more, and the average hydroxyl value is 300 to 85.
A nitrogen-containing polyether polyol of 0 mgKOH / g is preferred. A more preferred range of the average number of functional groups is 3 to 5. The average hydroxyl value is 300 to 700 mg KOH.
/ G is preferred, and 300 to 550 mgKOH / g is particularly preferred. If the average hydroxyl value is less than 300 mgKOH / g, the compressive strength of the open-cell foamed synthetic resin does not appear, and 850
If it exceeds mgKOH / g, it is difficult to handle due to high viscosity.
Easy to become closed cells. The content ratio of the nitrogen-containing polyol (B) is 40 to 80% by mass, more preferably 45 to 75% by mass, and preferably 50 to 70% by mass, based on the total amount of the polyols (A), (B) and (C). % By weight is particularly preferred.

The polyol (C) has an average number of functional groups of 2
And a polyol having an average hydroxyl value of 300 to 1500 mgKOH / g. The polyol (C) is characterized in that it does not contain a nitrogen atom. Suitable polyols (C) include water, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol,
Average hydroxyl value obtained by reacting alkylene oxide with at least one polyhydric alcohol selected from glycerin and trimethylolpropane or at least one selected from the polyhydric alcohol and water as an initiator, 300 to 1500 mgKOH / g Of polyether polyols. When the average hydroxyl value of the polyol (C) is less than 300 mgKOH / g, it becomes difficult to form open cells. The average hydroxyl value of the polyol (C) is 500
~ 1200 mgKOH / g, preferably 500-100
0 mg KOH / g is particularly preferred. The content ratio of the polyol (C) in the polyol mixture is 5 to 3 with respect to the total amount of the polyols (A), (B) and (C).
0 mass%, preferably 10 to 25 mass%.

In the present invention, the polyol mixture composed of the polyols (A), (B) and (C) has an average hydroxyl value of 380 mgKOH / g or more. Three
If it is less than 80 mgKOH / g, the strength of the open-cell foamed synthetic resin is difficult to obtain. The average hydroxyl value of the polyol mixture is
400-800 mgKOH / g is more preferable, and 410
Particularly preferred is -600 mg KOH / g. In the present invention, an active hydrogen compound other than the polyols (A), (B) and (C) can be used in combination. Examples of the active hydrogen compound include a compound having two or more phenolic hydroxyl groups and an aminated polyol.

As the compound having two or more phenolic hydroxyl groups, a resol-type initial condensate in which a phenol is condensed and bound with an excess of formaldehyde in the presence of an alkali catalyst, when synthesizing a resol-type initial condensate, There are benzylic ether type precondensates reacted in an aqueous system, and novolak type precondensates obtained by reacting excess phenols with formaldehydes in the presence of an acid catalyst. The molecular weight of these precondensates is preferably from 200 to 10,000. Here, the phenols mean those in which one or more carbon atoms of a skeleton forming a benzene ring are directly bonded to a hydroxyl group, and include those having another substituent in the same structure. Representative phenols include phenol, cresol, bisphenol A, resorcinol and the like. The formaldehyde is not particularly limited, but formalin and paraformaldehyde are preferred. The present invention relates to the use of water as a blowing agent in polyol 100.
Use 6 to 14 parts by mass with respect to parts by mass. Especially 6-12
It is preferable to use it by mass%. Further, in the present invention, it is preferable to use water as a sole foaming agent,
Depending on the purpose, a low boiling halogenated hydrocarbon may be used in combination as a foaming agent.

The low-boiling halogenated hydrocarbon is not particularly limited, but includes 1,1-dichloro-1-fluoroethane (HCFC-141b), chlorodifluoromethane (HCFC-22), 1,1,1,2. -Tetrafluoroethane (HFC-134a), 1-chloro-1,1-difluoroethane (HCFC-142b), 1,1-dichloro-2,2,3,3,3-pentafluoropropane (HCFC-225ca), 1,3-dichloro-1,
1,2,2,3-pentafluoropropane (HCFC-
225cb), pentafluoroethane (HFC-12
5), 1,1,2-trifluoroethane (HFC-14
3), 1,1,1-trifluoroethane (HFC-14
3a), 1,1,1,2,3,3-hexafluoropropane (HFC-236ea) and its isomers,
1,2,2,3-pentafluoropropane (HFC-2
45ca) and isomers thereof, 1,1,1,4,4,4
-Hexafluorobutane (HFC-356mff),
1,1,1,3,3-pentafluoropropane (HFC
-245fa), 1,1,1,3,3-pentafluorobutane (HFC-365mff) and the like. In addition, a low boiling halogenated hydrocarbon containing no fluorine such as methylene chloride can be used in combination as a blowing agent. Although it is not preferable to use halogenated hydrocarbons as a blowing agent in view of environmental issues, the technology of the present invention increases the number of parts of water to be used without reducing the performance of the foamed synthetic resin. Can be greatly reduced. When a low-boiling halogenated hydrocarbon is used in combination as the blowing agent, the usage ratio of the low-boiling halogenated hydrocarbon is preferably 0 to 500 parts by mass with respect to 100 parts by mass of water.

In addition, hydrocarbons such as butane, pentane and hexane, and inert gases such as air and nitrogen can be used together as a foaming agent. When using an inert gas as a foaming agent, the usage ratio of the inert gas is preferably from 0 to 500 parts by mass with respect to 100 parts by mass of water. Examples of the polyisocyanate compound include aromatic, alicyclic, and aliphatic polyisocyanates having two or more isocyanate groups, and modified polyisocyanates obtained by modifying them. One type of polyisocyanate compound may be used, or a mixture of two or more types may be used.

Specifically, for example, tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate (commonly known as Crude M)
DI), xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and other polyisocyanates, and urethane-modified, nurate-modified, urea-modified, and carbodiimide-modified products thereof. The polyisocyanate compound is represented by 100 times the number of isocyanate groups to the total number of active hydrogens of the polyol and other active hydrogen compounds (usually, 100
The value expressed in times is called the isocyanate index) 50-3
00, preferably 80 to 150, particularly preferably 85 to
It is desirable to use it so as to be in the range of 120.

When reacting a polyol with a polyisocyanate compound, it is usually necessary to use a catalyst. Examples of the catalyst include a metal compound catalyst such as an organotin compound that promotes the reaction between an active hydrogen-containing group and an isocyanate group, and a tertiary amine catalyst such as triethylenediamine. In addition, a multimerization catalyst for reacting isocyanate groups with each other, such as a metal carboxylate, is used depending on the purpose. The amount of the catalyst used may be appropriately selected, but is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyol.

Further, in the present invention, a foam stabilizer for forming good air bubbles is used. Examples of the foam stabilizer include a silicone-based foam stabilizer and a fluorine-containing compound-based foam stabilizer. The amount of the foam stabilizer may be appropriately selected, but is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyol. In addition, as a compounding agent which can be optionally used as a raw material, for example, there are a filler, a stabilizer, a coloring agent, a flame retardant and the like.
The reaction temperature condition of the present invention is not particularly limited as long as it is a temperature at which open cells can be foamed, but is usually preferably in the range of 0 to 50 ° C, particularly preferably in the range of 15 to 40 ° C. According to the present invention, even if a large amount of water is used as a foaming agent, the foamed synthetic resin of open cells does not collapse, and a special silicone foam stabilizer with low solubility and without using a hydrophobic polyol are excellent. The raw material storage stability is improved, and an open-cell synthetic resin foam can be easily obtained. The foamed synthetic resin produced in the present invention is an open cell and has a closed cell ratio of 50%.
It is preferable to be as follows. ADVANTAGE OF THE INVENTION According to this invention, the rigid foam synthetic resin of the open cell of the closed cell rate of 0-50% can be easily prepared according to the objective. By setting the closed cell ratio to 50% or less, the characteristics of the open-celled rigid foam synthetic resin, such as improvement of dimensional stability and reduction of the foaming pressure, can be further brought out.

[0023]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. In Examples and Comparative Examples, parts mean parts by mass.

Examples 1 to 5 1.5 parts of a foaming agent, a general-purpose silicone foam stabilizer and an amine catalyst (necessary amount for a gel time of about 35 seconds) based on the polyols (100 parts in total) in the combinations shown in Table 1 Was mixed. This mixed solution and crude MDI were mixed with isocyanate groups: active hydrogen groups = 1: 1 (isocyanate index 100).
And mixed at a liquid temperature of 20 ° C., and put into a 200 × 200 × 200 mm wooden box to foam. The density (kg / m ³ ), compressive strength (PM
a), closed cell rate (%) and dimensional stability at 70 ° C. and 95% relative humidity were evaluated. The results are shown in Table 1.

[0025]

[Table 1]

Note: The abbreviations of polyols in Table 1 indicate the following. A1: Functional group number 3 obtained by reacting propylene oxide with glycerin as an initiator, hydroxyl value 35 mg KO
H / g, a polyether polyol having a constitutional unit based on ethylene oxide of 0% and a primary hydroxyl group of 0% of all hydroxyl groups. A2: Functional group 3 obtained by reacting propylene oxide with glycerin as an initiator, hydroxyl value 56 mg KO
H / g, a polyether polyol having a constitutional unit based on ethylene oxide of 0% and a primary hydroxyl group of 0% of all hydroxyl groups. A3: reacting sorbitol with propylene oxide,
Then, a polyether polyol having 6 functional groups, a hydroxyl value of 56 mgKOH / g, a structural unit based on ethylene oxide of 5%, and a primary hydroxyl group of 35% of all hydroxyl groups obtained by an ethylene oxide reaction.

B1: The number of functional groups obtained by reacting propylene oxide with ethylenediamine is 4, and the hydroxyl value is 500.
mg KOH / g polyether polyol. B2: The number of functional groups obtained by reacting propylene oxide with ethylenediamine is 4, and the hydroxyl value is 300 mgKOH /
g of polyether polyol. B3: The number of functional groups obtained by reacting propylene oxide with tolylenediamine is 4, and the hydroxyl value is 350 mgKOH /
g of polyether polyol. B4: Functional group 3 obtained by reacting propylene oxide with monoethanolamine, hydroxyl value 500 mg KO
H / g polyether polyol. B5: average functional group 3.5 obtained by reacting propylene oxide with a reaction product of nonylphenol, monoethanolamine and formaldehyde, and a hydroxyl value of 460 mgK
OH / g polyether polyol. C1: Dipropylene glycol Note) The additives in Table 1 are as follows. Flame retardant: tris (β-chloropropyl) phosphate Foam stabilizer: Silicone foam stabilizer, manufactured by Nippon Unicar, SZ-
1646 Catalyst: N, N, N ', N'-tetramethylhexamethylenediamine, Tosoh Corporation, MR

Comparative Examples 1 to 3 In the same manner as in the Examples, a foaming agent and a general-purpose silicone foam stabilizer were added to a combination of polyols (100 parts in total) shown in Table 2.
5 parts and the amine catalyst (the amount required for a gel time of about 35 seconds) were mixed. This mixed solution and crude MDI were mixed at an isocyanate group: active hydrogen group = 1: 1 (isocyanate index: 100) at a liquid temperature of 20 ° C., and 200 × 200
It was put into a wooden box of 200 mm and foamed.
Density of the obtained polyurethane foam (kg / m ³ ),
Compressive strength (PMa ), Closed cell rate (%), 70 ° C., and dimensional stability at 70 ° C. and 95% relative humidity. Table 2 shows the results.

[0029]

[Table 2]

[0030]

According to the present invention, it is possible to produce an open-cell foam synthetic resin having good dimensional stability without separation during storage of a polyol formulation or the like.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiromitsu Takeyasu 3-474-2 Tsukakoshi, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Asahi Glass Co., Ltd. (72) Hirotsugu Hotta 2--8-8 Yaesu, Chuo-ku, Tokyo Yaesu Building F-term in Asahi Glass Urethane Co., Ltd. KC18 KD12 KD24 NA02 NA03 QA02 QC01

Claims (5)

[Claims] 1. A method for producing a rigid foam synthetic resin by reacting a polyol with a polyisocyanate compound in the presence of a foaming agent, a foam stabilizer and a catalyst, wherein the polyol (A) is a structural unit based on ethylene oxide in the molecule. Is 5% by mass or less, and primary hydroxyl groups are 1% of all hydroxyl groups.
5% or less, average number of functional groups is 2 or more, average hydroxyl value is 20
5 to 25% by mass of a polyol of 〜120 mg KOH / g,
(B) produced by an initiator containing a nitrogen atom, having an average number of functional groups of 3 or more and an average hydroxyl value of 300 to 850 mg KO
H / g of a nitrogen-containing polyol of 40 to 80% by mass, and (C) an average number of functional groups of 2 to 3 and an average hydroxyl value of 300 to 300
5 to 30% by mass of a polyol of 1500 mgKOH / g,
Using a polyol mixture having an average hydroxyl value of 380 mg KOH / g or more, and using water as a foaming agent in an amount of 6 to 14 parts by mass with respect to 100 parts by mass of the polyol mixture. Method. 2. Polyol (A) is water, glycerin,
The method for producing a rigid foam synthetic resin according to claim 1, which is a polyether polyol obtained by reacting an alkylene oxide with at least one initiator selected from trimethylolpropane, diglycerin, pentaerythritol, sorbitol and sucrose. 3. The nitrogen-containing polyol (B) is obtained by reacting an alkylene oxide with at least one initiator selected from a polyamine, an alkanolamine, and a Mannich reaction product of a phenol, an alkanolamine and an aldehyde. The method for producing a rigid foam synthetic resin according to claim 1 or 2, which is a polyether polyol. 4. The polyol (C) is at least one polyhydric alcohol selected from ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, and trimethylolpropane, or at least one selected from the polyhydric alcohol and water. A polyether polyol obtained by reacting an alkylene oxide with one kind of an initiator.
3. The method for producing a rigid foam synthetic resin according to any one of the above items 3. 5. The method for producing a rigid foam synthetic resin according to claim 1, wherein the closed cell rate of the foam synthetic resin is 50% or less.