JPH01225612A - Preparation of expanded synthetic resin - Google Patents

Abstract

PURPOSE:To prepare a good expanded synthetic resin without causing clouding and foam breaking, by reacting an active hydrogen compd. with a polyisocyanate compd. in the presence of a specified silicone foam stabilizer and a specified foaming agent. CONSTITUTION:An expanded synthetic resin is prepared by reacting an active hydrogen compd. (A) having 2 or more active hydrogen-contg. functional groups capable of reacting with an NCO group (e.g., polyether polyol obtd. by adding an alkylene oxide) with a polyisocyanate compd. (B) (e.g., polymethylenepolyphenyl isocyanate) in the presence of a silicone foam stabilizer (C) and a foaming agent (D). Said stabilizer C is a foam stabilizer of polydimethylsiloxane-polyoxyalkylene block copolymer contg. 35wt.% or more polydimethylsiloxane and said agent D is a foaming agent, at least part of which is 1,1-dichloro-1-fluoroethane. As said agent D exhibits high solubility in said compd. A and agent C, a good expanded synthetic resin can be obtd. thereby without causing clouding in the mixed liq. and foam breaking in expanding.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for producing a foamed synthetic resin such as a polyurethane foam, and in particular a method for producing a foamed synthetic resin characterized by the use of a specific blowing agent. It is about the method.

[Prior Art] Producing a foamed 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 blowing agent. is widely practiced. Examples of active hydrogen compounds include polyhydroxy compounds and polyamine compounds. As the foam stabilizer, polydimethylsiloxane-polyoxyalkylene block copolymers, so-called silicone foam stabilizers, are widely used. Examples of the foamed synthetic resin that can be obtained include polyurethane foam,
Examples include polyisocyanurate foam and polyurea foam. In addition, examples of foamed synthetic resins with relatively low foaming include microcellular polyurethane elastomer and microcellular polyurethane urea elastomer.

Although various compounds are known as blowing agents for producing the above-mentioned foamed synthetic resin, trichlorofluoromethane (R-11) is mainly used. Also 1 normal R-
Water is further used in combination with 11. Furthermore, when foaming is carried out by the froth method etc., dichlorodifluoromethane (R
-12) is used in combination. Furthermore, various proposals have been made that other fluorine-containing halogenated hydrocarbons with relatively low boiling points can be used as blowing agents, but with the exception of the above-mentioned 11 and R-12, they are still not widely used. However, the use of other low-boiling point halogenated hydrocarbon blowing agents such as methylene chloride in place of the fluorine-containing halogenated hydrocarbon blowing agent has also been proposed.

[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 phase separation problems. There was a problem of narrowing the range of usable active hydrogen compounds. When phase separation occurs in a mixed system with an active hydrogen compound, R-11 with heavy specific gravity accumulates at the bottom of the storage container.
Because the mixture becomes inhomogeneous, the reaction equivalence with the polyisocyanate compound is disrupted, making it impossible to obtain a normal foam. Even if there is no clear separation into two phases, poor solubility can lead to foaming due to polymerization and foaming. During body production, this tends to lead to poor mixing with the polyisocyanate compound, residual unreacted components, and the generation of rough foam called voids.

On the other hand, polydimethylsiloxane-polyoxyalkylene block copolymer, which is a silicone foam stabilizer, has a hydrophilic part and a hydrophobic part, and has the effect of a surfactant.
It has the effect of adjusting the shape of the bubbles in the foam. - It is believed that the higher the polydimethylsiloxane content of this compound used in the shell, the finer the bubbles and the lower the thermal conductivity. Here, the polydimethylsiloxane content is polydimethylsiloxane-
Represents the weight percent of polydimethylsiloxane in one molecule of polyoxyalkylene block copolymer, but
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 blowing agent in active hydrogen compounds and increases the aforementioned This will promote the phenomenon of phase separation. When the polydimethylsiloxane content exceeds 35%, the system liquid containing the active hydrogen compound, catalyst, foam stabilizer, and blowing agent begins to become cloudy. This cloudiness is a state in which phase separation has begun to occur in minute units. Furthermore, if a foam stabilizer with a high polydimethylsiloxane content is used, foam breakage occurs during foaming. For this reason, it has been impossible to use a foam stabilizer with a polydimethylsiloxane content higher than a certain level. For these reasons, it is desired to develop a foaming agent that has high solubility with active hydrogen compounds and silicone foam stabilizers.

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

2 active hydrogen-containing functional groups that can react with isocyanate groups
A method for producing a foamed synthetic resin by reacting an active hydrogen compound having the above and a polyisocyanate compound in the presence of a silicone foam stabilizer and a blowing agent, wherein the polydimethylsiloxane content as the silicone foam stabilizer is 35% by weight. A foamed synthetic resin characterized by using the above polydimethylsiloxane-polyoxane alkylene block copolymer silicone foam stabilizer and using 1,1-dichloro-1-fluoroethane as at least a part of the foaming agent. Production method.

1,1-dichloro-1-fluoroethane, which is a blowing agent in the present invention, is a compound with a boiling point of 32°C;
-Dichloro-! - Fluoroethane has high solubility in active hydrogen compounds such as polyols, solubility in active hydrogen compounds in the coexistence of water, and R-11 and R-1.
It has high solubility in fluorine-containing halogenated hydrocarbon blowing agents such as No. 2 and silicone foam stabilizers, and reduces problems caused by the solubility between the above-mentioned halogenated hydrocarbon blowing agents and active hydrogen compounds. I can do it.

Water is often used in combination with the halogenated hydrocarbon blowing agent. Examples of blowing agents other than waterside that can be used in combination include low-boiling halogenated hydrocarbons other than those mentioned above, low-boiling hydrocarbons, and inert gases. 1. l-dichloro-1-
Examples of low-boiling halogenated hydrocarbons other than fluoroethane include halogenated hydrocarbons that do not contain fluorine atoms, such as methylene chloride, and fluorine-containing halogenated hydrocarbons other than those mentioned above. Low-boiling hydrocarbons include butane and hexane, and inert gases include air and nitrogen. 1,1-dichloro-1-fluoroethane in the present invention can be used alone or in combination with other blowing agents.

As mentioned 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 has high solubility in active hydrogen compounds or mixtures of active hydrogen compounds and silicone foam stabilizers. It also has high solubility in 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 (i.e., a compatibilizer) for increasing the solubility of a foaming agent that has low solubility in active hydrogen compounds and silicone foam stabilizers containing a large amount of polydimethylsiloxane (and mixtures thereof with water). It can be used as When using 1.1-dichloro-1-fluoroethane as a compatibilizer, R-11 and R-12 are preferred as blowing agents with low solubility, and the amount used is 1.1-dichloro-1-fluoroethane. 1 for the total of fluoroethane and low-solubility halogenated hydrocarbon blowing agent
．． The amount of 1-dichloro-1-fluoroethane is at least 2% by weight, preferably from 5 to 100% by weight, especially 15
An amount of ~70% by weight is preferred.

2 active hydrogen-containing functional groups that can react with isocyanate groups
The active hydrogen compound having the above is a compound having two or more active hydrogen-containing functional groups such as a hydroxyl group or an amino group, or a mixture of two or more such compounds. Particularly preferred are compounds having two or more hydroxyl groups, mixtures thereof, or mixtures containing the same as the main component and further containing polyamine or the like. As the compound having two or more hydroxyl groups, widely used polyols are preferred, but compounds having two or more phenolic hydroxyl groups (for example, phenol resin initial condensate) can also be used. Polyols include polyether polyols, polyester polyols,
Examples include polyhydric alcohols and diethylene polymers containing hydroxyl groups. In particular, the polyether polyols are preferably composed of one or more polyether polyols, or are preferably used in combination with polyester polyols, polyhydric alcohols, polyamines, alkanolamines, and other active hydrogen compounds. Preferred are polyether polyols obtained by adding a cyclic ether, particularly an alkylene oxide such as propylene oxide or ethylene oxide, to a polyhydric alcohol, saccharide, alkanolamine, or other initiator. Further, as the polyol, it is also possible to use a polyol composition called a polymer polyol or a graft polyol, in which fine particles of a vinyl polymer are dispersed in a mainly polyether polyol. Examples of polyester polyols include polyhydric alcohols, polycarboxylic acid condensation polyols, and cyclic ester ring-opening polymer polyols; examples of polyhydric alcohols include ethylene glycol, propylene glycol,
These include diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, pentaerythritol, jetanolamine, and triethanolamine. Compounds having two or more phenolic hydroxyl groups include resol-type initial condensates in which phenols are condensed and bonded with excess formaldehyde in the presence of an alkali catalyst; There are benzylic-type precondensates made by reacting excess phenols with formaldehyde in the presence of an acid catalyst, and novolac-type precondensates. The molecular weight of these initial condensates is preferably 200 to 1000G. Here, 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 within the same structure. Typical examples include phenol, cresol, and bisphenol A-rusorcinol. Further, the formaldehyde is not particularly limited, but formalin and formaldehyde are preferable. The hydroxyl value of the polyol or the mixture of active hydrogen compounds is often selected from about 20 to 1000 depending on the purpose.

Examples of polyisocyanate compounds 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 polyphenylisocyanate (common name: crude MDI),
Examples include polyisocyanates such as xylylene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate, as well as prepolymer-type modified products, nurate-modified products, and urea-modified products thereof.

When reacting active hydrogen compounds and polyisocyanate compounds, the use of catalysts is usually required. As a catalyst,
Metal compound catalysts such as organotin compounds and tertiary amine catalysts such as triethylenediamine are used to promote the reaction between active hydrogen-containing groups and isocyanate groups. Further, a polymerization catalyst that causes isocyanate groups to react with each other, such as a carboxylic acid metal salt, is used depending on the purpose. Other optional additives include fillers, stabilizers, colorants, flame retardants, and the like.

Using these raw materials, polyurethane foam, urethane-modified polyisocyanerate foam, microcellular polyurethane elastomer, microcellular polyurethane urea elastomer, microcellular polyurea elastomer, and other foamed synthetic resins can be obtained.

Polyurethane foam can be roughly divided into rigid polyurethane foam, semi-rigid polyurethane foam, and flexible polyurethane foam.

It is particularly useful in the production of rigid polyurethane foams, urethane-modified polyisocyanurate foams, and other rigid foams, which are fields in which halogenated hydrocarbon blowing agents are used in large quantities. Among them, the hydroxyl value is 200
It is particularly useful in the production of rigid polyurethane foams obtained using polyols or mixtures of polyols and aromatic polyisocyanate compounds. When producing these rigid foams, the halogenated hydrocarbon blowing agent is often used in an amount of 5 to 150% by weight, especially 20 to 60% by weight, based on the active hydrogen compound. 10% by weight relative to the compound
It is also possible to use up to On the other hand, in the case of flexible polyurethane foam, semi-rigid polyurethane foam, and microcellular elastomer, the halogenated hydrocarbon blowing agent is 5 to 150% by weight based on the active hydrogen compound.
In particular, it is often used in an amount of 20 to 60% by weight. Furthermore, in the case of flexible polyurethane foam, water is added to the
In the case of a microcellular elastomer, it is preferable to use 0 to 5% by weight. It is believed that 1,1-dichloro-1-fluoroethane in the present invention is also effective in producing foams using other halogenated hydrocarbon blowing agents.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

The polyols used in the examples are as follows.

Polyoluminum: Hydroxyl value 32 made by reacting phthalic anhydride with butanediol and then reacting with ethylene oxide.
Polyether polyol of No. 5 Polyol B: Polyol with a hydroxyl value of 315 made by reacting phthalic anhydride and diethylene glycol Polyol C: A hydroxyl value of 45 made by reacting metatoluenediamine with ethylene oxide and propylene oxide
0 polyether polyol [Example] Table 1 shows the solubility results of the blowing agent and silicone foam stabilizer in the present invention in the above polyols.

The solubility is 2 g of silicone foam stabilizer with a polydimethylsiloxane content of 45% per 100 g of polyol, and the following ■ ~
The liquids to which 100 g of the halogenated hydrocarbon blowing agent (1) had been added were stirred and then left to stand for evaluation.

Note that R-141b represents 1.1-dichloro-1-fluoroethane.

■ R-11100% ■ R-1195%, R-141b 5% ■ R-1
190%, R-141b In%■ R-1180%
, R-141b 20% ■ R-1150%, R-
141b The criteria for 50% judgment are as follows.

(About solubility) O: Transparent, homogeneous liquid △: Cloudy (state where phase separation has occurred in a minute range) Foaming evaluation was conducted as follows.

Comparative example ■: polyol a, polyol b, polyol C
using a silicone foam stabilizer containing 30% by weight of ordinary polydimethylsiloxane,
Foaming was carried out using dichloro-1-fluoroethane.

Example ■: Polyol a, polyol B, polyol C
Foaming was carried out using a silicone foam stabilizer containing 40% by weight of polydimethylsiloxane and 1,1-dichloro-1-fluoroethane as a foaming agent.

Comparative example ■: polyol a, polyol b, polyol C
Using a silicone foam stabilizer with a regular polydimethylsiloxane content of 30% by weight, 1.1-
Foaming was carried out using a mixture of dichloro-1-fluoroethane and R-11 in a ratio of 1:1.

Example 2: Polyol a and polyol b were used, a silicone foam stabilizer containing 50% by weight of polydimethylsiloxane was used, and 1,1-dichloro-! was used as the foaming agent. - Foaming was carried out using a 1:1 mixture of fluoroethane and R-11.

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

Foaming method> For 100 parts by weight of polyol, 2 parts of silicone foam stabilizer, 1 part of water, the necessary amount of N,N-dimethylcyclohexylamine as a catalyst for a gel time of 45 seconds, 1
．． A mixture of 1-dichloro-1-fluoroethane and polymethylene polyphenylisocyanate (MD Kasei ■
Product name PAP I I 35) was mixed at a liquid temperature of 20°C,
It was put into a wooden box measuring 200 mm x 200 mm x 200 mm, and was foamed for evaluation. The amount of foaming agent used was adjusted so that the foam core density was 30±1 kg/m''.

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

(About the shape of the foam) A: Good foam shape B: Cell roughness is observed and shrinkage C: Cell roughness is observed and shrinkage is extremely large [Effects of the invention] Halogenated hydrocarbon type in the present invention Foaming agents include silicone foam stabilizers with high solubility in active hydrogen compounds and high polydimethylsiloxane content, and foaming agents with low solubility with active hydrogen compounds such as R-11 and silicone foam stabilizers with high polydimethylsiloxane content. A silicone foam stabilizer with a high solubility and a high content of active hydrogen compounds and polymethylsiloxane, and a silicone foam stabilizer with a high content of an active hydrogen compound and polydimethylsiloxane such as a foaming agent with a low solubility. It has an excellent effect of solving problems such as phase separation.

Claims (1)

[Claims] 1. A foamed 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 silicone foam stabilizer and a foaming agent. In the manufacturing method, the content of polydimethylsiloxane as a silicone foam stabilizer is 35% by weight.
Using the above polydimethylsiloxane-polyoxane alkylene block copolymer silicone foam stabilizer,
A method for producing a foamed synthetic resin, characterized in that 1,1-dichloro-1-fluoroethane is used as at least a part of the foaming agent. 2. Polydimethylsiloxane content is 50 as a foam stabilizer
2. The method of claim 1, wherein at least % by weight of silicone foam stabilizer is used. 3. The method according to claim 1, wherein the blowing agent consists of 1,1-dichloro-1-fluoroethane and water and/or other low-boiling halogenated hydrocarbon blowing agents. 4. The foamed synthetic resin is a rigid polyurethane foam.
The method according to claim 1.