JP2526974B2 - Method for producing foamed synthetic resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a foamed synthetic resin such as polyurethane foam, and particularly to the production of a foamed synthetic resin characterized by the use of a specific foaming agent. It is about the method.

[Prior Art] To produce an expanded 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, a foam stabilizer and a foaming agent. Is widely practiced. Examples of active hydrogen compounds include polyhydroxy compounds and polyamine compounds. As the foam stabilizer, a polydimethylsiloxane-polyoxyalkylene block copolymer, so-called silicone foam stabilizer is widely used. Examples of the foamed synthetic resin obtained include polyurethane foam, polyisocyanurate foam, and polyurea foam. Further, examples of the foamed synthetic resin having a relatively low foaming include microcellular polyurethane elastomer and microcellular polyurethane urea elastomer.

Various compounds are known as a foaming agent for producing the foamed synthetic resin, but trichlorofluoromethane (R-11) is mainly used. Also, usually R-
Water is used together with 11. Further, when foaming is performed by the floss method or the like, dichlorodifluoromethane (R
-12) is also used. Various proposals have been made that other fluorine-containing halogenated hydrocarbons having a relatively low boiling point can be used as a blowing agent.
Except for -11 and R-12, it is not yet widely used. It has also been proposed to use other low-boiling halogenated hydrocarbon-based blowing agents such as methylene chloride in place of the fluorine-containing halogenated hydrocarbon-based blowing agent.

[Problems to be Solved by the Invention] R-11, which has been widely used in the past, generally has low solubility in active hydrogen compounds such as polyols, and a mixed component system containing both tends to cause a problem of phase separation. There is a problem that the range of active hydrogen compounds that can be used is limited. When phase separation occurs in a mixed system with an active hydrogen compound, R-11, which has a high specific gravity, accumulates at the bottom of the storage container to form an inhomogeneous mixed solution, and the reaction equivalent with the polyisocyanate compound is changed, resulting in normal foaming. I can't get a body.
Poor solubility, even if it is not clearly divided into two phases, is likely to lead to poor mixing with the polyisocyanate compound during polymerization and foam production by foaming, residual unreacted components, and generation of coarse bubbles called voids.

On the other hand, the silicone foam stabilizer, polydimethylsiloxane-polyoxyalkylene block copolymer, has a hydrophilic portion and a hydrophobic portion, has the effect of a surfactant, and has the function of adjusting the shape of the foam of the foam. It is a thing.
It is generally considered that the larger the content of polydimethylsiloxane in this compound, the finer the bubbles and the lower the thermal conductivity. Here, the polydimethylsiloxane content represents the weight% of polydimethylsiloxane in one molecule of polydimethylsiloxane-polyoxyalkylene block copolymer. However, an increase in the polydimethylsiloxane content leads to an increase in the hydrophobic portion of the polydimethylsiloxane-polyoxyalkylene block copolymer, which deteriorates the solubility of the halogenated hydrocarbon-based blowing agent in the active hydrogen compound, Will promote the phenomenon of phase separation.
When the content of polydimethylsiloxane exceeds 35%, white turbidity begins to occur in the system liquid in which the active hydrogen compound, catalyst, foam stabilizer and foaming agent are mixed. This white turbidity is a state in which phase separation begins to occur in fine units. Further, when a foam stabilizer having a high polydimethylsiloxane content is used, the foam is broken during foaming. For this reason, it is impossible to use a foam stabilizer having a polydimethylsiloxane content higher than a certain level. For these reasons, it is desired to develop a foaming agent having high solubility with active hydrogen compounds and silicone foam stabilizers.

[Means for Solving the Problems] The present invention provides the following inventions made to solve the above-mentioned problems.

A method for producing a foamed synthetic resin 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 silicone foam stabilizer and a foaming agent, comprising: A polydimethylsiloxane-polyoxyalkylene block copolymer-based silicone foam stabilizer having a polydimethylsiloxane content of 35% by weight or more is used as an agent, and 1,1-dichloro-1-fluoroethane is used as at least a part of the foaming agent. A method for producing a foamed synthetic resin, which is characterized by being used.

The blowing agent 1,1-dichloro-1-fluoroethane in the present invention is a compound having a boiling point of 32 ° C., and the 1,1-dichloro-1-fluoroethane is soluble in active hydrogen compounds such as polyols and water. It has high solubility in active hydrogen compounds in the coexistence and high solubility in fluorine-containing halogenated hydrocarbon foaming agents such as R-11 and R12 and silicone foam stabilizers, and the above-mentioned halogenated hydrocarbon foaming agents and active hydrogen compounds. The problems due to the solubility between the two can be reduced.

Water is often used in combination with the halogenated hydrocarbon blowing agent. Examples of the blowing agent other than water that can be used in combination include low-boiling halogenated hydrocarbons other than the above, low-boiling hydrocarbons, and inert gases. 1,1-dichloro-1-
The low-boiling-point halogenated hydrocarbons other than fluoroethane include halogenated hydrocarbons containing no fluorine atom such as methylene chloride and fluorine-containing halogenated hydrocarbons other than the above. Low-boiling hydrocarbons include butane and hexane, and inert gases include air and nitrogen. The 1,1-dichloro-1-fluoroethane in the present invention can be used alone or in combination with other foaming agents.

As described above, 1,1-dichloro-1-fluoroethane not only has high solubility in active hydrogen compounds or mixtures of active hydrogen compounds and silicone foam stabilizers, but also R-11, R-12, etc. It also has a high solubility for other halogenated hydrocarbon blowing agents. Therefore, 1,1-dichloro-1-fluoroethane has the effect of increasing the compatibility between the two. That is, an additive (that is, a compatibilizer) for enhancing the solubility of a foaming agent having a low solubility in an active hydrogen compound and a silicone foam stabilizer having a high content of polydimethylsiloxane (and a mixture thereof with water). Can be used as When 1,1-dichloro-1-fluoroethane is used as a compatibilizer, R-11 and R-12 are preferable as the foaming agent having low solubility. Also, its usage is 1,1
1,1-dichloro-based on the total of dichloro-1 fluoroethane and a halogenated hydrocarbon blowing agent having low solubility
An amount of at least 2% by weight of 1-fluoroethane, preferably 5 to 100% by weight, particularly 15 to 70% by weight is preferred.

The active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group is 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 kinds of the compounds. Especially 2
The above-mentioned compound having a hydroxyl group, a mixture thereof, or a mixture containing the compound as a main component and further containing polyamine or the like is preferable. 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. As a polyol,
Examples include polyether polyols, polyester polyols, polyhydric alcohols, hydroxyl group-containing diethylene polymers. In particular, it is preferable to use only one or more polyether polyols, or to use them in combination with polyester polyols, polyhydric alcohols, polyamines, alkanolamines and other active hydrogen compounds.
Polyether-based polyols include polyhydric alcohols,
Polyether-based polyols obtained by adding cyclic ethers, particularly alkylene oxides such as propylene oxide and ethylene oxide, to saccharides, alkanolamines and other initiators are preferable. Further, as the polyol, it is also possible to use a polyol composition, which is called a polymer polyol or a graft polyol, in which fine particles of vinyl polymer are dispersed mainly in a polyether polyol. Polyester polyols include polyhydric alcohols, polyhydric carboxylic acid condensation polyols and cyclic ester ring-opening polymer polyols, and polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol,
Examples include glycerin, trimethylolpropane, pentaerythritol, diethanolamine and triethanolamine. As the compound having two or more phenolic hydroxyl groups, when a phenol-based condensation product is combined with excess formaldehyde in the presence of an alkali catalyst, a resol-type initial condensate or a resol-type initial condensate is reacted in a non-aqueous system. Examples thereof include a benzylic type initial condensate, and a novolak type initial condensate obtained by reacting excess phenols with formaldehydes in the presence of an acid catalyst. The molecular weight of these precondensates is preferably 200 to 10,000. Here, the phenols mean those in which one or more carbon atoms of the skeleton forming the benzene ring are directly bonded to a hydroxyl group, and also include those having other substituted bonding groups in the same structure. Typical examples include phenol, cresol, bisphenol A, resorcinol and the like. Formaldehydes are not particularly limited, but formalin and paraformaldehyde are preferable. The hydroxyl value of the polyol or the mixture of active hydrogen compounds is often selected from the range of about 20 to 1000 according to the purpose.

Examples of the polyisocyanate compound include aromatic, alicyclic, or aliphatic polyisocyanates having two or more isocyanate groups, mixtures of two or more thereof, and modified polyisocyanates obtained by modifying them. Specifically, for example, tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate (common name: crude MDI),
Examples include 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 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 or a tertiary amine catalyst such as triethylenediamine that accelerates the reaction between the active hydrogen-containing group and the isocyanate group is used. Further, a multimerization catalyst for reacting isocyanate groups such as a metal carboxylate is used depending on the purpose. As other optional additives, for example, fillers,
There are stabilizers, colorants, flame retardants, etc.

By using these raw materials, polyurethane foam, urethane-modified polyisocyanate foam, microcellular polyurethane elastomer, microcellular polyurethane urea elastomer, microcellular polyurea elastomer, and other foam synthetic resins can be obtained. Polyurethane foams are roughly classified into rigid polyurethane foams, semi-rigid polyurethane foams, and flexible polyurethane foams. The present invention is particularly useful in the production of rigid polyurethane foams, urethane-modified polyisocyanurate foams, and other rigid foams, which is a field in which a large amount of halogenated hydrocarbon-based blowing agents is used. Among them, it is particularly useful for producing a rigid polyurethane foam obtained by using a polyol or a mixture of polyols having a hydroxyl value of about 200 to 900 and an aromatic polyisocyanate compound. When manufacturing these rigid foams, the halogenated hydrocarbon-based blowing agent is often used in an amount of 5 to 150% by weight, particularly 20 to 60% by weight, based on the active hydrogen compound. It is also possible to use water up to 10% by weight based on the active hydrogen compound. On the other hand, flexible polyurethane foam and semi-rigid polyurethane foam,
Even in the case of Mycelular Cellular Elastomer, the halogen-valent hydrocarbon type blowing agent is 5 to 150% of the active hydrogen compound.
%, Especially 20-60% by weight is often used. In addition, water is added to it in the case of flexible polyurethane foam.
10% by weight, 0-5 for microcellular elastomers
It is preferable to use it together in a weight percentage. It is considered that the 1,1-dichloro-1-fluoroethane in the present invention is also effective in the production of foams using other halogenated hydrocarbon blowing agents.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

 The polyols used in the examples are as follows.

Polyol a: Polyether polyol having a hydroxyl value of 325 obtained by reacting phthalic anhydride with butanediol and further reacted with ethylene oxide Polyol b: Polyol having a hydroxyl value of 315 obtained by reacting phthalic anhydride with diethylene glycol Polyol c: Metatoluenediamine Polyether polyol having a hydroxyl value of 450 obtained by reacting ethylene oxide and propylene oxide [Example] Table 1 shows the results of the solubility of the foaming agent and the silicone foam stabilizer in the present invention in the above polyols.

The solubility was evaluated in a state in which 2 g of a silicone foam stabilizer having a polydimethylsiloxane content of 45% and 100 g of a halogenated hydrocarbon-based foaming agent described below were added to 100 g of a polyol, and the mixture was left standing after stirring.

R-141b represents 1,1-dichloro-1-fluoroethane.

 R-11 100% R-11 95%, R-141b 5% R-11 90%, R-141b 10% R-11 80%, R-141b 20% R-11 50%, R-141b 50% Judgment The criteria are as follows.

<Solubility> ○: Transparent, homogeneous liquid △: White turbidity (phase separation occurs in a fine range) ×: Clear separation into two phases The evaluation of foaming of the above-mentioned polyol by the method of the present invention was carried out as follows.

Comparative example: polyol a, polyol b, polyol c
With normal polydimethylsiloxane content of 30% by weight
Foaming was carried out using 1,1-dichloro-1-fluoroethane as the foaming agent, using the silicone foam stabilizer of (1).

Examples: polyol a, polyol b, polyol c
Was used to foam with a silicone foam stabilizer having a polydimethylsiloxane content of 40% by weight and 1,1-dichloro-1-fluoroethane as a foaming agent.

Comparative example: polyol a, polyol b, polyol c
With normal polydimethylsiloxane content of 30% by weight
Foaming was performed using the silicone foam stabilizer of No. 1 and a mixture of 1,1-dichloro-1-fluoroethane and R-11 in a 1: 1 ratio as a foaming agent.

Example: Polyol a and polyol b were used with a silicone foam stabilizer having a polydimethylsiloxane content of 50% by weight, and 1,1-dichloro-1-fluoroethane R-11 was used as a foaming agent in a ratio of 1: 1. Foaming was performed using the mixture.

The foaming method is as follows. The results are shown in Table 2.

<Foaming method> 2 parts of a silicone-based foam stabilizer, 1 part of water, and N, N-dimethylcyclohexylamine as a catalyst, the necessary amount for making the gel time 45 seconds, with respect to 100 parts by weight of polyol, 1,1-
A mixture of dichloro-1-fluoroethane and polymethylene polyphenylisocyanate (MD Chemicals Co., Ltd., trade name PAPI 135) are mixed at a liquid temperature of 20 ° C. to obtain 200 mm × 200 mm × 200 m
It was put in a m wooden box, foamed and evaluated. The amount of the foaming agent used was adjusted so that the foam core density was 30 ± 1 kg / m ³ .

The criteria for determining the foam appearance in Table 2 are as follows.

<Regarding the shape of the foam> A: Good foam shape B: Cellular cracks are observed and shrinkage is observed C: Cellular cracks are observed and the shrinkage is extremely large [Effect of the invention] Halogenated hydrocarbon system of the present invention The foaming agent has a low solubility with respect to active hydrogen compounds and a silicone foam stabilizer having a high polydimethylsiloxane content, and a low solubility with active hydrogen compounds such as R-11 and a silicone foam stabilizer having a high polydimethylsiloxane content. , A foaming agent having a high solubility with respect to active hydrogen compounds and a silicone foam stabilizer having a high content of polymethylsiloxane, and a low solubility of a silicone foam stabilizer having a high content of active hydrogen compounds such as R-11 and a polydimethylsiloxane. It has an excellent effect of solving the problems such as phase separation of.

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Claims (4)

(57) [Claims] 1. A method for producing a foamed synthetic resin 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 silicone foam stabilizer and a foaming agent. , The silicone foam stabilizer has a polydimethylsiloxane content of 35
Foaming synthesis characterized by using a polydimethylsiloxane-polyoxyalkylene block copolymer-based silicone foam stabilizer in an amount of at least wt% and using 1,1-dichloro-1-fluoroethane as at least a part of the foaming agent. Resin manufacturing method. 2. The method according to claim 1, wherein a silicone foam stabilizer having a polydimethylsiloxane content of 50% by weight or more is used as the foam stabilizer. 3. The process according to claim 1, wherein the blowing agent comprises 1,1-dichloro-1-fluoroethane and water and / or another low boiling halogenated hydrocarbon-based blowing agent. 4. The method according to claim 1, wherein the foamed synthetic resin is a rigid polyurethane foam.