JPH06306137A - Production of rigid foamed synthetic resin - Google Patents

Abstract

PURPOSE:To produce an open-celled foamed synthetic resin having a high dimensional stability without causing the ozone destruction problem by reacting a specific active hydrogen compd. component with a polyisocyanate compd. in the presence of water as the blowing agent, a catalyst and a silicone foam stabilizer. CONSTITUTION:A component comprising 20-90wt.% active hydrogen compd. with a mean functionality of 4 or higher and a mean hydroxyl value of 300 mgKOH/g or higher and 80-10wt.% active hydrogen compd. with a mean functionality of 4 or lower and a mean hydroxyl value of 200mgKOH/g or lower is used as the active hydrogen compd. component and water in an amt. of 3-10wt.% of the above component is used as the blowing agent in the process for producing a rigid foamed synthetic resin by reacting the active hydrogen compd. component comprising active hydrogen compds. each having at least two isocyanate-reactive active hydrogen groups with a polyisocyanate compd. in the presence of the blowing agent, a catalyst, and a silicone foam stabilizer. Thus, it is obtd. an open-celled foamed synthetic resin with a high dimensional stability while using water, which releases carbon dioxide, as a blowing agent not destroying the ozone layer.

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 rigid foam synthetic resin such as a rigid polyurethane foam, and more particularly to the production of a rigid foam synthetic resin characterized by the use of a specific foaming agent.

[0002]

2. Description of the Related Art It has been widely practiced to produce a rigid foam synthetic resin by reacting an active hydrogen compound having two or more active hydrogen-containing groups capable of reacting with an isocyanate group with a polyisocyanate compound in the presence of a catalyst or the like. There is. A polyhydroxy compound is mainly used as the active hydrogen compound. Examples of the obtained hard foam synthetic resin include hard urethane foam and hard polyisocyanurate foam.

There are closed cells and open cells as the states of cells of the hard foam synthetic resin. Each of the closed-cell foam cells is sealed, and a foaming agent having a low thermal conductivity such as trichlorofluoromethane (R-11) can be enclosed therein, and the foam has excellent heat insulation performance.

The open-cell foam has air permeability because individual cells are connected to each other. For this reason, the open-cell foam has low heat insulation performance, but has excellent dimensional stability under severe temperature conditions. These foams are used properly according to the application.

Various compounds are known as a foaming agent for producing a foamed synthetic resin, but R-11 has been mainly used. Further, water was usually used together with R-11. Furthermore, when foaming is performed by the froth method or the like, dichlorodifluoromethane (R-12) having a lower boiling point (a gas under normal temperature and pressure) has been used together with these.

Also, various proposals have been made that other chlorinated fluorinated hydrocarbons having a relatively low boiling point can be used as a blowing agent. However, the above R-11 and R-
Except for 12, it is not yet widely used. It has also been proposed to use other halogenated hydrocarbon-based blowing agents such as methylene chloride in place of the chlorinated fluorinated hydrocarbon-based blowing agent.

[0007]

A part of the chlorinated fluorinated hydrocarbon used as a foaming agent leaks to the atmosphere, so its use may not be a cause of ozone layer depletion. I'm afraid there isn't. Therefore, there is an increasing need to reduce the amount of such chlorinated fluorinated hydrocarbon blowing agents used or to replace them with other blowing agents.

As a method for solving the above problems, it has been proposed to use a large amount of water as a foaming agent. Water is a primary blowing agent in flexible polyurethane foams and an important secondary blowing agent in rigid polyurethane foams. However, it is difficult to use the fluorinated chlorinated hydrocarbons used as the main blowing agent in rigid polyurethane foam in a high enough ratio to replace them.

A foamed synthetic resin containing a large amount of water has a problem that it is gradually deformed when left at room temperature for a long period of time even if its initial performance is good. In order to use water as a foaming agent which replaces the conventional fluorinated chlorinated hydrocarbon type foaming agent, it is necessary to develop a technique for solving these problems.

In order to cope with poor dimensional stability of a foam by a formulation using a large amount of water as a foaming agent, it is conceivable to connect the foam to each other in applications where heat insulation performance is not important. However, current hard urethane resin communication technology has a problem in handling the prescription. A special silicone foam stabilizer is required to make it open, or an active hydrogen compound having hydrophobicity is mixed and used. Therefore, the mixed raw materials cannot be stored for a long time because the mixed raw materials become cloudy or separated. The generalization of open-ended prescription also requires a means to solve this problem.

[0011]

The present invention has been made to solve the above-mentioned problems, that is, to provide an active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group and a polyisocyanate compound. In the method for producing a rigid foam synthetic resin by reacting in the presence of a foaming agent, a catalyst and a silicon foam stabilizer, (A) the average number of functional groups is 4 or more and the average hydroxyl value is 300 m as an active hydrogen compound.
20 to 90% by weight of gKOH / g or more and (B) average number of functional groups of 4 or less, average hydroxyl value of 200 mg
KOH / g or less is used in an amount of 80 to 10% by weight and water is used as a blowing agent in an amount of 3 to 10% by weight based on the active hydrogen compound. is there.

In the present invention, the active hydrogen compound (A) has an average number of functional groups of 4 or more and an average hydroxyl value of 300 mg.
20 to 90% by weight of KOH / g or more and (B)
Average number of functional groups is 4 or less, average hydroxyl value is 200mgKOH
80 to 10% by weight of less than / g is used.

The active hydrogen compound is preferably a compound having two or more active hydrogen-containing functional groups such as a hydroxyl group and an amino group. As the compound having two or more hydroxyl groups, a widely used polyol is preferable, but a compound having two or more phenolic hydroxyl groups (for example, a phenol resin initial condensation product) can also be used.

Examples of polyols include polyether polyols, polyester polyols, hydroxyl group-containing diethylene-based polymers and the like.

Polyether polyols include polyhydric alcohols, sugars, alkanolamines, other initiators, and cyclic ethers, especially propylene oxide (P
O), ethylene oxide (EO), and a polyether polyol obtained by adding butylene oxide are preferable.
Further, a polyol composition in which fine particles of vinyl polymer are dispersed in a polyol mainly composed of a polyether polyol called a polymer polyol or a graft polyol can also be used.

Polyester polyols include polyhydric alcohols, polyhydric carboxylic acid condensation polyols and cyclic ester ring-opening polymer type polyols, and polyhydric alcohols include ethylene glycol, propylene glycol,
Examples include diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, pentaerythritol, diethanolamine and triethanolamine.

As the compound having two or more phenolic hydroxyl groups, when a phenol is condensed with excess formaldehyde in the presence of an alkali catalyst to synthesize a resol type initial condensate or a resol type initial condensate, There are a benzylic ether type precondensate reacted in an aqueous system and a novolak type precondensate obtained by reacting excess phenols with formaldehyde in the presence of an acid catalyst. The molecular weight of these initial condensates is preferably 200 to 10,000. Here, the phenols mean those in which one or more carbon atoms of the skeleton forming a benzene ring are directly bonded to a hydroxyl group, and also include those having other substituent bonding groups in the same structure. Typical phenols include phenol, cresol, bisphenol A, resorcinol and the like. Formaldehydes are not particularly limited, but formalin and paraformaldehyde are preferable.

In the present invention, the active hydrogen compound (A),
It is particularly preferred to use a polyether polyol as (B). (A) As the active hydrogen compound having an average number of functional groups of 4 or more and an average hydroxyl value of 300 mgKOH / g or more, as described in Japanese Patent Application No. 4-173924, at least one selected from sucrose, sorbitol, and methyl glucoside. Average hydroxyl value obtained by reacting an initiator containing PO with 300 to 550 mgKOH
/ G of polyether polyol is preferred.

As the active hydrogen compound (B) having an average number of functional groups of 4 or less and an average hydroxyl value of 200 mgKOH / g or less, at least one selected from glycerin, trimethylolpropane, diglycerin, pentaerythritol and propylene glycol is PO or PO. A polyether polyol obtained by reacting EO is preferable. In particular, polyether polyol having a hydroxyl value of 10 to 150 mgKOH / g is preferable. Hydroxyl value 20-130mgKOH /
More preferably g. Further, the active hydrogen compound (B) preferably has a polymer chain based on EO in the molecule, and in this case, it is preferable that the proportion of EO is 20% by weight or more.

In addition to the active hydrogen compounds (A) and (B), a small amount of polyhydric alcohol, polyamine, alkanolamine or the like may be used in combination.

According to the technique of the present invention, an open-cell foam can be obtained without using a special silicone foam stabilizer having a low solubility or a hydrophobic active hydrogen compound. With the technique according to the present invention, a foamed synthetic resin having a closed cell ratio of 50 to 0% can be prepared according to the purpose. When the closed cell ratio is less than 50%, it is possible to bring out the features of the open-celled rigid foam synthetic resin, such as improved dimensional stability and reduced foaming pressure.

In the present invention, it is preferable to use water as a foaming agent in an amount of 3 to 10% by weight based on the active hydrogen compound. It is particularly preferable to use 5 to 10% by weight. Further, although the technique of the present invention can be used for a formulation in which water is used as the sole foaming agent, a compound having a low boiling point halogenated hydrocarbon can be used in combination as the foaming agent.

The low-boiling halogenated hydrocarbon is not particularly limited, but it is 1,1-dichloro-2,2,2-trifluoroethane (R-123), 1,1-dichloro-1-.
Fluoroethane (R-141b), chlorodifluoromethane (R-22), 1,1,1,2-tetrafluoroethane (R-134a), 1-chloro-1,1-difluoroethane (R-142b), 1 , 1-dichloro-2,
2,3,3,3-pentafluoropropane (R-225
ca), 1,3-dichloro-1,1,2,2,3-pentafluoropropane (R-225cb), pentafluoroethane (R-125), 1,1,2-trifluoroethane (R-143). ), 1,1,1-trifluoroethane (R-143a), 1,1-difluoroethane (R-1)
52a), tetrafluoropropane, 1,1,1,2,
3,3-hexafluoropropane (R-236ea) and its isomers, 1,1,2,2,3-pentafluoropropane (R-245ca) and its isomers, 1,
1,1,4,4,4-hexafluorobutane (R-35
6 mff) and its isomers, and the like, include halogenated hydrocarbons containing hydrogen atoms called alternative CFCs.

In addition, halogenated hydrocarbons containing no fluorine such as methylene chloride, hydrocarbons such as butane, pentane and hexane, and inert gases such as air and nitrogen can be used together as a foaming agent.

The polyisocyanate compound includes aromatic, alicyclic or aliphatic polyisocyanates having two or more isocyanate groups and modified polyisocyanates obtained by modifying them. As the polyisocyanate compound, one type may be used, or a mixture of two or more types may be used.

Specifically, for example, tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate (common name: Crude MD)
I), polyisocyanates such as xylylene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate, and their prepolymer-type modified products, nurate modified products, and urea modified products.

When reacting the active hydrogen compound and the polyisocyanate compound, it is usually necessary to use a catalyst. As the catalyst, a metal compound-based catalyst such as an organic tin compound that accelerates the reaction between the active hydrogen-containing group and the isocyanate group,
A tertiary amine catalyst such as triethylenediamine is used. Further, a multimerization catalyst for reacting isocyanate groups such as carboxylic acid metal salt is used depending on the purpose.

Further, a foam stabilizer for forming good bubbles is often used. Examples of the foam stabilizer include a silicone-based foam stabilizer and a fluorine-containing compound-based foam stabilizer. In addition, examples of the compounding agent that can be optionally used include a filler, a stabilizer, a coloring agent, and a flame retardant.

The foamed synthetic resin produced by the present invention is open-celled, and the closed cell ratio is preferably 50% or less. A closed cell ratio of 35% or less is particularly preferable. More preferably, it is 20% or less.

[0030]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Parts are parts by weight. Rigid polyurethane foams were produced according to the invention. Examples 1-2 are comparative examples, Examples 3-
32 is an embodiment. The polyols A to G used are shown in Table 1.

[0031]

[Table 1]

The combinations of polyols shown in Table 2 (total 1
Amount of the foaming agent shown in Table 3 to 100 parts),
1.5 parts of a silicone foam stabilizer for continuous formulation and an amine catalyst (a necessary amount for obtaining a gel time of about 65 seconds) were mixed. This mixture and crude MDI (index 11
0) is mixed at a liquid temperature of 20 ° C., and 200 × 200 × 200 m
It was put in a wooden box of m and foamed.

The density (k) of the obtained polyurethane foam
g / m ³ ), compressive strength (kg / cm ² ), closed cell ratio (%), and room temperature dimensional stability were evaluated. The evaluation results are shown in Table 4 ~
Summarize in 7. However, the room-temperature dimensional stability was represented by the presence or absence of deformation of the sample that was left at room temperature for 1 week after foaming.

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

[Table 6]

[0039]

[Table 7]

[0040]

INDUSTRIAL APPLICABILITY According to the present invention, a specific CFC having a risk of ozone depletion is replaced with a blowing agent having a risk of ozone depletion, such as water releasing carbon dioxide, to produce a continuous foam synthetic resin having good dimensional stability. Is what you can do.

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[Procedure amendment]

[Submission date] June 16, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 4

[Correction method] Change

[Correction content]

Claims (5)

[Claims] 1. A hard foam synthetic resin is produced by reacting an active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group with a polyisocyanate compound in the presence of a foaming agent, a catalyst and a silicon foam stabilizer. In the method described above, the active hydrogen compound (A) having an average number of functional groups of 4 or more and an average hydroxyl value of 300 mgKOH / g or more is 2
0 to 90% by weight and (B) 80 to 1 having an average number of functional groups of 4 or less and an average hydroxyl value of 200 mgKOH / g or less.
0% by weight and 3 to 10% by weight of water as a blowing agent with respect to the active hydrogen compound are used to produce a rigid foam synthetic resin having open cells. 2. A hydroxyl value of 150 to 10 mgKOH / g obtained by reacting an active hydrogen compound (A) with an alkylene oxide to at least one selected from glycerin, trimethylolpropane, diglycerin, pentaerythritol and propylene glycol. 2. The method according to claim 1, which is the polyether polyol. 3. The method according to claim 1, wherein water is used as a foaming agent in an amount of 5 to 10% by weight based on the active hydrogen compound. 4. An average hydroxyl value of 150 obtained by reacting an active hydrogen compound (A) with at least one compound selected from glycerin, trimethylolpropane, diglycerin, pentaerythritol and propylene glycol with ethylene oxide and propylene oxide. ~ 10 mg
The production method according to claim 1, wherein the polyether polyol is KOH / g, and the proportion of ethylene oxide in the molecule is 20% by weight or more. 5. The method according to claim 1, wherein the foamed synthetic resin has a closed cell ratio of 50% or less.