JPH01225608A - 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. 35% or more polydimethylsiloxane and said agent D is a foaming agent, at least part of which is dibromofluoromethane. 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 copolymer foam stabilizers, so-called silicone foam stabilizers, are widely used. Examples of the foamed synthetic resins that can be obtained include polyurethane foam, polyisocyanurate foam, and polyurethane 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, usually R
Water is further used in combination with -11. Furthermore, when foaming is carried out by the froth method, etc., dichlorodifluoromethane (which is a gas at room temperature and pressure), which has a lower boiling point (gaseous at normal temperature and pressure)
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 R-11 and R-12 mentioned above, they are still widely used. It has not yet reached the point where it will be done. Furthermore, the use of other low-boiling point halogenated hydrocarbon blowing agents such as methylene chloride in place of the fluorine-containing halogenated hydrocarbon blowing agents 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.
Since the mixture becomes heterogeneous, the reaction equivalence with the polyisocyanate compound is disturbed, and a normal foam cannot be obtained. Even if there is no clear separation into two phases, poor solubility tends to lead to poor mixing with the polyisocyanate compound, residual unreacted components, and generation of rough foam called voids during the production of foams by polymerization and foaming.

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. Generally, it is thought that the higher the content of polydimethylsiloxane in this compound, the finer the bubbles and the lower the thermal conductivity. Here, the polydimethylsiloxane content represents the average weight percent of polydimethylsiloxane in one molecule of the 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 blowing agent in active hydrogen compounds.

11; This promotes the phase separation phenomenon described in 1. When the polydimethylsiloxane content exceeds 35% by weight, 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
In 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 foaming agent, the polyisocyanate compound having a polydimethylsiloxane content of 35% or more is used as the silicone foam stabilizer. 1. A method for producing a foamed synthetic resin, which comprises using a dimethylsiloxane-polyoxydialkylene block copolymer foam stabilizer, and using a foaming agent at least partially composed of dibromodifluoromethane.

Dibromodifluoromethane, which is a blowing agent in the present invention, is a compound with a boiling point of 24.5°C. High solubility in fluorine-containing halogenated hydrocarbon blowing agents such as -11 and R-12 and silicone foam stabilizers, resulting from the solubility between the halogenated hydrocarbon blowing agents and active hydrogen compounds. Problems can be reduced.

Water is often used in combination with a halogenated hydrocarbon blowing agent (O;j). Other blowing agents that can be used in conjunction with waterside include:
Examples include low-boiling halogenated hydrocarbons, low-boiling hydrocarbons, and inert gases other than those mentioned above. Examples of low-boiling halogenated hydrocarbons other than dibromodifluoromethane include halogenated hydrocarbons that do not contain a fluorine atom, 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. Dibromodifluoromethane in the present invention can be used alone or in combination with other blowing agents.

As mentioned above, dibromodifluoromethane 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 such as -12. Therefore, dibromodifluoromethane 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 dibromodifluoromethane is used as a compatibilizing agent, preferred blowing agents with low solubility are T-11 and R-12.

The amount used is such that dibromodifluoromethane is at least 2% by weight, preferably 5 to 100% by weight, particularly 15 to 80% by weight
The amount is preferable.

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, it is preferable to use only one or more types of polyether polyols, or to use them as a main component in combination with polyester polyols, polyhydric alcohols, polyamines, alkanolamines, and other active hydrogen compounds. The polyether polyol is preferably a polyether polyol 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. Polyester polyols include polyhydric alcohols, polycarboxylic acid condensation polyols, and cyclic ester ring-opening polymer polyols. 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 with excess formaldehyde in the presence of an alkaline catalyst; There are benzylic-type initial condensates made by reacting with 1, and novolac-type initial condensates made by reacting excess phenols with formaldehyde in the presence of Tf as an acid catalyst. The molecular weight of these initial condensates is preferably 200 to 1000.

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. As a matter of fact, phenol.

Examples include cresol, bisphenol A, and resorcinol. Further, formaldehydes are not particularly limited, but formalin and paraformaldehyde are preferred. The hydroxyl value of the polyol or the mixture of active hydrogen compounds is about 20~
It is often selected from over 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 (commonly known as 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 an active hydrogen compound and a polyisocyanate compound, 1 the use of a catalyst 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 Mizukidai radicals and isocyanate groups. Further, a polymerization catalyst for reacting isocyanate species such as carboxylic acid metal salts with each other is used depending on the purpose. Other optional additives include, for example, fillers, stabilizers, colorants, and flame retardants.

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

Polyurethane foam can be broadly divided into rigid polyurethane foam, semi-rigid polyurethane foam, and flexible polyurethane foam. The present invention 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 these, it is particularly useful in the production of rigid polyurethane foams obtained by using polyols or polyol mixtures having a hydroxyl value of 200 to 900 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, particularly 20 to 60% by weight, based on the active hydrogen compound. It is also possible to use up to 10% by weight of water, based on the active hydrogen compound. On the other hand, in the case of flexible polyurethane foam, semi-rigid polyurethane foam, and microcellular elastomer, the halogenated hydrocarbon blowing agent is used in an amount of 5 to 150% by weight, especially 20 to 60% by weight, based on the active hydrogen compound. There are many. Furthermore, it is preferable to use 4 to 10% by weight of water in the case of a flexible polyurethane foam, and 0 to 5% by weight in the case of a microcellular elastomer. The dibromodifluoromethane of the present invention is also considered to be 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 325 made by reacting phthalic anhydride with butanediol and then reacting with ethylene oxide.
polyether polyol polyol B: polyol with a hydroxyl value of 315 made by reacting phthalic anhydride and diethyl glycol Polyol C: polyether polyol with a hydroxyl value of 450 made by reacting metatoluenediamine with ethylene oxide and propylene oxide [Example] Table 1 shows the solubility and foaming results of the foaming agent and silicone foam stabilizer in the present invention in the above polyol.

Solubility was evaluated by adding 2 g of a silicone foam stabilizer with a polydimethylsiloxane content of 45% by weight and 100 g of halogenated hydrocarbon foaming agents listed below to 100 g of polyol, stirring the solution and then allowing it to stand still. did.

Foaming evaluation was performed as follows. For 100 parts by weight of polyol, 2 parts of silicone foam stabilizer with a polydimethylsiloxane content of 45% by weight, 1 part of water, and N and N as catalysts.
- Necessary amount of dimethylcyclohexylamine to give a gel time of 45 seconds, a mixture of the following halogenated hydrocarbon blowing agents (■ to ■) and polymethylene polyphenylisocyanate (MD Kasei ■ Product name PAP I 135)
) were 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. In addition, 9! The amount of foaming agent used was adjusted so that the foam core density was 30±I kg/m3. The percentages in the following blowing agent compositions are by weight, R-12
82 represents dibromodifluoromethane.

■ R-11100% ■ R-1195%, R-12B2 5% ■ R-1
190%, R-1282In%■ R-1180%, R
-12B2 20%■ R-1150%, R-12B
2 The criteria for 50% judgment are as follows.

Regarding solubility〉 O: Transparent, homogeneous liquid Δ: Cloudy (phase separation has occurred in a minute range) ×: Regarding the shape of a foam that clearly separates into two phases〉 A: With a good foam shape B: The cell shape is uneven and some voids are observed C: There is uneven mixing and voids are seen everywhere Table 1 [Effects of the Invention] The halogenated hydrocarbon blowing agent in the present invention is active hydrogen Silicone foam stabilizers with high solubility in compounds and high polydimethylsiloxane content, and high solubility in foaming agents that have low solubility with active hydrogen compounds such as (1) and silicone foam stabilizers with high polydimethylsiloxane content. ,
Problems such as phase separation between a silicone foam stabilizer with a high content of active hydrogen compounds and polymethylsiloxane and a foaming agent with low solubility from a silicone foam stabilizer with a high content of active hydrogen compounds and polydimethylsiloxane such as R-11. It has an excellent effect of solving the problem.

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, a polydimethylsiloxane-polyoxyalkylene block copolymer foam stabilizer having a polydimethylsiloxane content of 35% or more is used as a silicone foam stabilizer, and at least a portion of the blowing agent is dibromodifluoromethane. A method for producing a foamed synthetic resin, characterized by using a 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 dibromodifluoromethane is used in combination with water and/or another low-boiling halogenated hydrocarbon blowing agent as the blowing agent. 4. The foamed synthetic resin is a rigid polyurethane foam.
The method according to claim 1.