JPH0830104B2 - 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-polyalkylene oxide block copolymer, a 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 large specific gravity, accumulates at the bottom of the storage container and becomes a heterogeneous mixed solution, so the reaction equivalent amount with the polyisocyanate compound is deviated and normal It is not possible to obtain a foam.
Poor solubility, even if it is not clearly divided into two phases, tends to result in poor mixing with the polyisocyanate compound during the production of a foam due to polymerization and 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 effect of adjusting the foam shape of the foam. It is a thing.
It is generally considered that the smaller the surface tension of a surfactant, the finer the bubbles and the lower the thermal conductivity. The present inventors have conducted various studies to obtain a foam stabilizer having a low surface tension, and as a result, by adding a fluorine atom to the molecule of the silicone foam stabilizer, the surface tension can be dramatically reduced. , And found to reduce the thermal conductivity. However, the addition of fluorine leads to an increase in the hydrophobic portion of the polydimethylsiloxane-polyoxyalkylene block copolymer, deteriorating the solubility of the halogenated hydrocarbon-based blowing agent in the active hydrogen compound and causing the above-mentioned phase It will promote the phenomenon of separation. In our experiments, generally, when the fluorine content exceeds 5%, the system liquid in which the active hydrogen compound, the catalyst, the foam stabilizer and the foaming agent are mixed begins to become cloudy. This white turbidity is a state in which phase separation begins to occur in fine units. Further, when a foam stabilizer having a high fluorine content is used, the foam is broken during foaming. However, with a fluorosilicone having a fluorine content of less than 5%, the reduction in surface tension reduction is insufficient. Therefore, it is very difficult to use the fluorosilicone foam stabilizer. For these reasons, it is desired to develop a foaming agent having high solubility with active hydrogen compounds and fluorosilicone foam stabilizers.

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

In the 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 foam stabilizer and a foaming agent, Fluorine content 5
% Or more, a fluorosilicone type foam stabilizer having a surface tension of 10 to 30 dyn / cm is used, and at least a part of the foaming agent is 1,1-
A method for producing a foamed synthetic resin, which comprises using a foaming agent which is dichloro-1-fluoroethane.

The foaming agent 1,1-dichloro-1-fluoroethane in the present invention is a compound having a boiling point of 27.1 ° C.
Dichloro-1-fluoroethane is soluble in active hydrogen compounds such as polyols and in the presence of water, and is soluble in active hydrogen compounds and fluorine-containing halogenated hydrocarbon blowing agents such as R-11 and R-12 and silicones. The solubility of the foam stabilizer is high, and the problems caused by the solubility between the halogenated hydrocarbon-based foaming agent and the active hydrogen compound 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-
Examples of low-boiling 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 is not only highly soluble in active hydrogen compounds or mixtures of active hydrogen compounds and fluorosilicone foam stabilizers, but also in R-11 and R-12. It also has high solubility in other halogenated hydrocarbon blowing agents such as. Therefore 1,1
-Dichloro-1-fluoroethane has the effect of increasing the compatibility between the two. That is, it is used as an additive (that is, a compatibilizer) for increasing the solubility of an active hydrogen compound, a fluorosilicone foam stabilizer having a high fluorine content (and a mixture thereof with water) having a low solubility. can do. When 1,1-dichloro-1-fluoroethane is used as a compatibilizer, R is a low-solubility foaming agent.
-11 and R-12 are preferred. The amount of 1,1-dichloro-1-fluoroethane and 1,1-dichloro-1-fluoroethane based on the total amount of the low-solubility halogenated hydrocarbon blowing agent are low.
An amount of at least 2% by weight of -fluoroethane, preferably 5 to 100% by weight, particularly 15 to 70% by weight is preferred.

In the present invention, the fluorosilicone foam stabilizer is a polydiorganosiloxane-polyoxyalkylene block copolymer foam stabilizer, and the polydiorganosiloxane block has a fluorine atom.
That is, a polydiorganosiloxane block containing a diorganosiloxane unit in which at least one of two monovalent organic groups bonded to a silicon atom is a monovalent organic group containing a fluorine atom, and a polyoxyalkylene. A silicone having a block. The polydiorganosiloxane block may consist of only fluorine-containing diorganosiloxane units or may have other diorganosiloxane units (particularly dimethylsiloxane units).
The polyoxyalkylene block may be bonded to one of the fluorine-containing diorganosiloxane units, but is preferably bonded to a diorganosiloxane unit containing no fluorine atom. A preferable fluorine-containing diorganosiloxane unit is a unit represented by the following formula [I].

R _f : a polyfluoroalkyl group having 1 or more carbon atoms.

R ¹ : an alkylene group having 1 to 6 carbon atoms.

R ² : A monovalent organic group.

R _f is preferably a perfluoroalkyl group having 1 to 8 carbon atoms, and particularly preferably a perfluoroalkyl group having 2 to 6 carbon atoms. As R ¹ , an alkylene group having 1 to 4 carbon atoms is preferable, and an ethylene group is particularly preferable. R ² is preferably a fluorine-containing alkyl group, an alkyl group or a phenyl group similar to the —R ¹ —Rf group, preferably an alkyl group having 1 to 4 carbon atoms, particularly a methyl group. Of the units of the above formula [I] in the polydiorganosiloxane block, a part of R ² may be a polyoxyalkylene block, but the polyoxyalkylene block is preferably a diorganosiloxane unit containing no fluorine atom. Exists in.

In the present invention, the fluorosilicone foam stabilizer has a fluorine content of 5% by weight or more, preferably 10% by weight.
The above are used. Particularly preferred fluorine content is 20
It is more than weight%. The surface tension of the fluorosilicone foam stabilizer is preferably 10 to 30 dyn / cm, and particularly preferably 10 to 20 dyn / cm.

The active hydrogen compound having two or more active hydrogen content functional groups capable of reacting with an isocyanate group is a compound having two or more active hydrogen content 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 a compound having two or more phenolic hydroxyl groups, a non-aqueous system is used when synthesizing a resole-type initial condensate or a resole-type initial condensate obtained by condensation-bonding phenols with excess formaldehyde in the presence of an alkali catalyst. 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, and resoncinol. 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 foam is roughly classified into rigid polyurethane foam, semi-rigid polyurethane foam, and rigid polyurethane foam. 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 elastomer, the halogenated hydrocarbon-based foaming 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 and ethylene oxide Polyether polyol having hydroxyl value of 450 reacted with propylene oxide [Example] Solubility and foaming results of the foaming agent and the silicone foam stabilizer in the present invention with respect to the above-mentioned polyols are shown in Table 1.

Fluorosilicone foam stabilizer with a fluorine content of 25% by weight and a surface tension of 15 dyn / cm per 100 g of polyol ^* 2
g, 100 g of the following halogenated hydrocarbon-based foaming agents were added to each of the liquids, and the liquids were stirred and evaluated in a state of standing.

* [C ₄ F ₉ CH ₂ CH ₂ (CH ₃ ) SiO] units, [(CH ₃ ) ₂ SiO] units, [CH ₃ R ³ SiO] units, and (C
Fluorosilicone having H ₃ ) ₃ Si end groups (R ³ is a polyoxyalkylene block).

 The evaluation of foaming was performed as follows.

To 100 parts by weight of polyol, 2 parts of fluorosilicone type foam stabilizer, 1 part of water, N, N-dimethylcyclohexylamine as a catalyst, necessary amount for gel time of 45 seconds, the following halogenated hydrocarbon type Liquid mixed with foaming agent and polymethylene polyphenyl isocyanate (MD
Kasei Co., Ltd. trade name PAPI135) is mixed at a liquid temperature of 20 ° C.
It was put into a wooden box of × 200 nm × 200 mm, foamed and evaluated. The amount of foaming agent used is 30 ±
Adjusted to 1 kg / m ³ . In the following foaming agent composition,% represents% by weight, and 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% R -11 20%, R-141b 80% R-11 10%, R-141b 90% The criteria for judgment are as follows.

(Solubility) ○: Transparent, homogeneous liquid △: White turbidity (phase separation occurs in a fine range) ×: Clear separation into two phases <Foam shape> A: Good foam shape Yes B: Some non-uniform cell shape and some voids are seen.

C: There is uneven mixing, and voids are found everywhere. [Effects of the Invention] The halogenated hydrocarbon-based foaming agent in the present invention is a fluorosilicone foam stabilizer having a high solubility and fluorine content in active hydrogen compounds, and a fluorosilicone foam foam having a high fluorine content and active hydrogen compounds such as R-11. R-, which has a high solubility in a foaming agent and a high content of active hydrogen compounds and a fluorine content, and R-
It has an excellent effect of solving problems such as phase separation of a foaming agent having low solubility with an active hydrogen compound such as 11 or a fluorosilicone foam stabilizer having a high fluorine content.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C08L 75:08

Claims (4)

[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 foam stabilizer and a foaming agent. A fluorosilicone foam stabilizer having a fluorine content of 5% or more and a surface tension of 10 to 30 dyn / cm is used as the foam stabilizer, and at least a part of the foaming agent is 1,1-dichloro-1-fluoroethane. A method for producing a foamed synthetic resin, comprising: 2. The method according to claim 1, wherein a fluorosilicone foam stabilizer having a fluorine content of 10% or more and a surface tension of 10 to 20 dyn / cm is used as the foam stabilizer. 3. The method according to claim 1, wherein 1,1-dichloro-1-fluoroethane is used in combination with water and / or another low-boiling halogenated hydrocarbon-based blowing agent as the blowing agent. 4. The method according to claim 1, wherein the foamed synthetic resin is a rigid polyurethane foam.