JP2002201249A - Method for producing rigid plastic foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a rigid polyurethane foam or a urethane modified rigid polyisocyanurate foam whereby a normal foam can be obtained even under conditions in which the atmospheric temperature during foam production is low in the case in which HCFC-141b is used as a blowing agent. SOLUTION: There is provided a method for producing a rigid polyurethane foam or a urethane-modified rigid polyisocyanurate foam, which process comprises reacting an active-hydrogen-containing compound with a polyisocyanate compound in the presence of a low-boiling halohydrocarbon blowing agent, wherein the blowing agent used is a mixture of 1-75 wt.% HFC-245fa with 99-25 wt.% HCFC-141b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a rigid polyurethane foam or a urethane-modified rigid polyisocyanurate foam, and more particularly to a rigid polyurethane foam or a urethane-modified rigid foam characterized by using a specific blowing agent. The present invention relates to a method for producing a polyisocyanurate foam.

[0002]

2. Description of the Related Art A rigid polyurethane foam or a polyisocyanate compound is reacted with an active hydrogen-containing compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group in the presence of a foam stabilizer, a catalyst and a foaming agent. The production of urethane-modified rigid polyisocyanurate foams is widely practiced. Various compounds are known as foaming agents for producing the rigid polyurethane foam or urethane-modified rigid polyisocyanurate foam, but 1,1-dichloro-1-fluoroethane (HCFC-141b) is mainly used. . Usually, water is used together with HCFC-141b.

[0003]

When HCFC-141b is used as a foaming agent, depending on the ambient temperature at the time of producing a rigid polyurethane foam or a urethane-modified rigid polyisocyanurate foam due to the high boiling point of the foaming agent. Insufficient foaming makes it difficult to obtain a normal foam. SUMMARY OF THE INVENTION The present invention has been made to solve the problems at the time of producing this rigid polyurethane foam or urethane-modified rigid polyisocyanurate foam, and has solved the problems by using a specific foaming agent.

[0004]

That is, a first invention of the present application is to provide a polyisocyanate compound comprising an active hydrogen-containing compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group and a low boiling halogenated hydrocarbon. In a method for producing a rigid polyurethane foam or a urethane-modified rigid polyisocyanurate foam by reacting in the presence of a system-based foaming agent, 1 to 75% by weight of HFC-245fa and 99 to 25% by weight of HCFC-141b are used as foaming agents. % Of a rigid polyurethane foam or a urethane-modified rigid polyisocyanurate foam characterized by using a mixture with a foam stabilizer and an active hydrogen-containing compound containing a catalyst. -50% by weight, and reacting the mixture with a polyisocyanate compound. A method for producing a rigid polyurethane foam or a urethane-modified rigid polyisocyanurate foam according to the first aspect of the present invention, wherein the third aspect uses the liquid temperature of the reaction solution containing a foaming agent at 10 ° C. or higher. This is a method for producing the rigid polyurethane foam or urethane-modified rigid polyisocyanurate foam of the first or second invention. Here, HFC-245fa
Is a hydrofluorocarbon represented by the structural formula (CHF ₂ CH ₂ CF ₃ ), and HCFC-141b is a hydrochlorofluorocarbon represented by the structural formula (CH ₃ CCl ₂ F).

Hereinafter, the present invention will be described in detail. HCFC
When -141b is used as a foaming agent, the rise of foaming tends to be delayed when the ambient temperature during production of the rigid polyurethane foam or urethane-modified rigid polyisocyanurate foam is low. This is thought to be due to the high boiling point of the blowing agent. In the production of a rigid polyurethane foam or a urethane-modified rigid polyisocyanurate foam, the role of a physical foaming agent such as HCFC-141b is that the foaming agent is vaporized by heat of reaction during polymerization of an active hydrogen compound and a polyisocyanate compound, This is to promote foaming of the hard plastic.

However, when the ambient temperature is lowered, a time lag occurs before the reaction heat required for vaporization is generated at the beginning of the reaction, during which the resinification reaction proceeds, and it is considered that a normal foam cannot be obtained. The present inventors have found that it is possible to use a low-boiling-point halogenated hydrocarbon blowing agent, HFC-245fa, in combination with HCFC-141b as a physical blowing agent to promote a foaming reaction. Alternatively, they have found that they are effective in producing urethane-modified rigid polyisocyanurate foams, and have reached the present invention. Further, it has been found that when the temperature of the reaction solution is 10 ° C. or higher, preferably 20 ° C. or higher, the effect of the low-boiling-point foaming assisted halogenated hydrocarbon is remarkably exhibited.

In the present invention, HFC-, a low-boiling halogenated hydrocarbon blowing agent used as one component of the blowing agent, is used.
The mixing amount of 245fa is 1 to 75% by weight, preferably 10%.
-60% by weight, more preferably 20-50% by weight. If the amount is less than 1% by weight, the foaming effect as a foaming agent cannot be exhibited, and if it exceeds 75% by weight, foaming of the foam is hindered by bumping of the low boiling point foaming agent. Examples of the active hydrogen-containing compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group include a compound having two or more active hydrogen-containing functional groups such as a hydroxyl group and an amino group, or a mixture of two or more of the compounds. Is mentioned. Particularly, a compound having two or more hydroxyl groups or a mixture thereof, or a mixture containing the compound as a main component and further containing a polyamine or the like is preferable. As the compound having two or more hydroxyl groups, a polyol widely used is preferable.

[0008] Polyols include polyether polyols, polyester polyols, polyhydric alcohols,
Examples thereof include polyamines and alkanolamines, and the combination use of these polyols and other active hydrogen compounds is preferred. As the polyether polyol, a polyether polyol obtained by adding a cyclic ether, particularly an alkylene oxide such as propylene oxide or ethylene oxide, to a polyhydric alcohol, a saccharide, an alkanolamine, a polyamine, or another initiator is preferable. Examples of the polyester-based polyol include a polyhydric alcohol-polycarboxylic acid condensation-based polyol and a cyclic ester ring-opening polymerization-based polyol.Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and the like.
Glycerin, trimethylolpropane, pentaerythritol, diethanolamine, triethanolamine and the like can be mentioned.

Examples of the polyisocyanate compound include aromatic, alicyclic and aliphatic polyisocyanates having two or more isocyanate groups, mixtures of two or more of them, and modified poly obtained by modifying them. Isocyanates. Specifically, for example, polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and their prepolymer-modified, nurate-modified, and urea-modified products And the like.

[0010] When reacting an active hydrogen compound with a polyisocyanate compound, it is usually necessary to use a catalyst. As the catalyst, a metal compound catalyst such as an organotin compound which promotes the reaction between the active hydrogen-containing group and the isocyanate group, or a tertiary amine catalyst such as triethylenediamine is used. In addition, a multimerization catalyst such as a metal carboxylate for reacting isocyanate groups with each other is used depending on the purpose. In addition, foam stabilizers to form good cells are often used. As the foam stabilizer, a silicone-based foam stabilizer is mainly exemplified. Other optional additives include, for example, fillers, stabilizers, coloring agents, and flame retardants.

Using these raw materials, a rigid polyurethane foam and a rigid urethane-modified isocyanurate foam can be obtained. The present invention is a rigid polyurethane foam which is a field in which a large amount of a halogenated hydrocarbon-based blowing agent is used,
Particularly useful in the production of urethane-modified rigid polyisocyanurate foams. Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0012]

EXAMPLES The evaluation of the blowing agent according to the invention in rigid polyurethane foams was carried out using examples and comparative examples.
The polyols used are as follows. Polyol A: Polyol having a hydroxyl value of 400 obtained by reacting propylene oxide with triethanolamine Polyol B: Polyol having a hydroxyl value of 450 obtained by reacting propylene oxide with shoe rose The evaluation of the foaming state was performed according to the following evaluation criteria. . ：: Good foaming, good foam rising ○ △: Good foaming, slightly delaying foam rising △: Long foaming, slow foam rising △ ×: Long foaming time , Form rises slowly

[0013]

Example 1 To a mixture of 50 parts by weight of polyol A and 50 parts by weight of polyol B, 2 parts by weight of a silicone-based foam stabilizer, 1 part by weight of water, and 1 part by weight of a DPG solution of triethylenediamine as a catalyst: 1 part by weight Table as parts and foaming agent
The reaction solution obtained by mixing the foaming agent shown in No. 1 with polymethylene polyphenyl isocyanate (commonly called Crude MDI) was mixed at a predetermined liquid temperature, and 200 mm × 20 at an ambient temperature of 10 ° C.
It was put into a 0 mm × 100 mm wooden box and foamed to obtain a foam. Table 1 shows the obtained results.

Comparative Example 1 A foam was obtained in the same manner as in Example 1 except that the foaming agent was changed as shown in Table 1. Table 1 shows the obtained results.

[0014]

[Table 1]

[0015]

According to the present invention, a normal rigid polyurethane foam or urethane-modified rigid polyisocyanurate foam can be produced even at a low ambient temperature.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F074 AA78 BA53 BA95 CA25 DA02 4J034 CA03 CA14 DF01 DG01 DG03 DG04 HA07 HC03 HC12 HC22 HC46 HC52 HC61 HC63 HC71 JA02 JA14 JA32 NA02 NA05 QB16 QC01

Claims (3)

[Claims] 1. A hard polyurethane comprising reacting an active hydrogen-containing 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 low-boiling halogenated hydrocarbon-based blowing agent. In a method for producing a foam or a urethane-modified rigid polyisocyanurate foam, HFC-2 is used as a blowing agent.
1 to 75% by weight of 45fa and 99 of HCFC-141b
A method for producing a rigid polyurethane foam or a urethane-modified rigid polyisocyanurate foam, characterized by using a mixture of the polyurethane resin and a urethane-modified rigid polyisocyanurate foam. 2. The hard material according to claim 1, wherein a foaming agent is mixed with an active hydrogen-containing compound containing a foam stabilizer and a catalyst in an amount of 2 to 50% by weight, and the mixture is reacted with a polyisocyanate compound. A method for producing a polyurethane foam or a urethane-modified rigid polyisocyanurate foam. 3. The temperature of a reaction solution containing a foaming agent is 10 ° C.
The method for producing a rigid polyurethane foam or a urethane-modified rigid polyisocyanurate foam according to claim 1 or 2, which is used as described above.