JPH01240512A - Production of expanded synthetic resin - Google Patents

Abstract

PURPOSE:To obtain the subject excellent resin without a fear of destroying ozonosphere, by using dichloromethane and low-boiling hydrocarbon as a foaming agent in combination and reacting an active hydrogen compound with a polyisocyanate compound. CONSTITUTION:Dichloromethane and a hydrocarbon having <=100 deg.C, preferably 10-55 deg.C boiling point (preferably n-pentane or 2-methylbutane) are used in combi nation as a foaming agent to react an active hydrogen compound (e.g., a polyether based polyol) having >=2 active hydrogen-containing functional groups reactive with an isocyanate and a polyisocyanate (e.g., tolylene diisocyanate). Thereby, the aimed resin is obtained.

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] It is widely practiced to produce 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 and a blowing agent. ing. Examples of active hydrogen compounds include polyhydroxy compounds and polyamine compounds. Examples of the resulting foamed synthetic resin include polyurethane foam, 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, usually R-
In addition to No. 11, water is also used in combination. Furthermore, when foaming is carried out by the froth method etc., dichlorodifluoromethane (R
-12) is used in combination. Various proposals have been made that other relatively low-boiling chlorinated fluorinated hydrocarbons can be used as blowing agents;
With the exception of No. 11 and R-12, they have not yet come into widespread use. It has also been proposed to use other low boiling point halogenated hydrocarbon blowing agents, such as methylene chloride, in place of the chlorinated fluorinated hydrocarbon blowing agents.

[Problem to be solved by the invention] Chlorinated fluorinated hydrocarbons, such as R-11 and R-12, which have been widely used in the past and are extremely stable in the atmosphere at °C, reach the ozone layer above the atmospheric layer without being decomposed. There, it was thought that it would be decomposed by the action of ultraviolet rays, etc., and that the decomposed products could destroy the ozone layer. Chlorinated fluorinated hydrocarbons such as those mentioned above used as blowing agents,
Because some of it leaks into the atmosphere, there are concerns that its use could be part of the cause of ozone layer depletion. Therefore, in place of R-11 and R-12, foaming agents that are less likely to cause ozone layer depletion are being developed. As a result, the inventors investigated the use of dichloromethane as a low-boiling halogenated hydrocarbon blowing agent. Since dichloromethane is a compound with a boiling point of 39.8° C. and contains hydrogen but does not contain fluorine, it is thought that there is little risk of the above-mentioned ozone layer depletion.

Furthermore, since its boiling point is relatively close to R-11, R-11
It can be cited as a very promising candidate for a blowing agent to replace . However, this dichloromethane has high solubility in active hydrogen compounds such as polyols and in the coexistence of water, and has a high solubility in conventional R-1.
It may be difficult to manufacture foams in the same manner as in Example 1. If the blowing agent has high solubility, it will not only dissolve into active hydrogen compounds such as polyols, but also dissolve into the foamed synthetic resin, causing softening, shrinkage, and cell irregularity in the foam, and even causing the foam to burst. There are many things that happen. Moreover, it also causes economical problems such as an increase in the amount of blowing agent used and an increase in demolding time. Therefore, in order to effectively use dichloromethane as a substitute for R-11, it is desired to develop a technology to control its solubility and solve the above problems.

[Means for Solving the Problems] The present invention provides the following inventions that have been made to solve the above-mentioned problems. That is, 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 incyanate with a polyisocyanate compound in the presence of a low-boiling halogenated hydrocarbon foaming agent. 1. A method for producing a foamed synthetic resin, characterized in that dichloromethane and a hydrocarbon having a boiling point of 100° C. or less are used together as a blowing agent.

In the present invention, hydrocarbon means a compound consisting only of carbon and hydrogen. Since the hydrocarbon in the present invention does not contain chlorine, it is considered that there is little risk of the ozone layer being destroyed. Furthermore, since its boiling point is relatively close to that of R-11, it can be used as a blowing agent in place of R-11.

Furthermore, hydrocarbons have low solubility in active hydrogen compounds, and by using them together with dichloromethane, problems caused by the high solubility of dichloromethane in active hydrogen compounds and foamed synthetic resins can be alleviated.

Although hydrocarbons are flammable, the degree of flammability can be reduced by mixing them with dichloromethane, which is non-flammable.
Depending on the mixing ratio, it can be made nonflammable or not exhibit a flash point. Hydrocarbons used in the present invention can be used in the same way as conventional single blowing agents, do not require major changes to conventional technology, and can increase the foaming ratio with the same amount of blowing agent. The boiling point is preferably 1000C or less, and more preferably the boiling point range is 10C or more and 50C or less. The proportion of hydrocarbons in the total weight of dichloromethane and hydrocarbons used is preferably 2% or more and 95% or less. Depending on the blend of other raw materials, if it is less than 2%, the effect of suppressing the solubility of the blowing agent in the active hydrogen compound and the foamed synthetic resin may not be observed.
Moreover, if it exceeds 95%, the solubility in the active hydrogen compound is too low, which may cause problems such as separation. For the same reason, it is more desirable that the proportion of hydrocarbons in the total weight of dichloromethane and hydrocarbons used is 5% to 50% or less.

In the present invention, the hydrocarbon has a boiling point of 10 to 5.
Hydrocarbons in the 5°C range are preferred.

Examples of hydrocarbons include 2-methylbutane (boiling point 2
7.9℃), n-pentane (boiling point 36.1℃) %
and 2,2-dimethylbutane (boiling point 49.7°C). More preferred are 2-methylbutane and n-pentane.

The blowing agents in the present invention can of course be used alone or in combination with other blowing agents. In particular, water is often used in combination with the above-mentioned low-boiling point organic compound blowing agent. Examples of blowing agents that can be used in combination with other non-waterside blowing agents include the current blowing agents R-11 and R-12, other low-boiling point halogenated hydrocarbons other than 1,1-dichloro-1-fluoroethane, and non-hydrocarbons. There are active gases. Although R-11 and R-12 may cause ozone layer destruction by themselves, their usage can be reduced by using them in combination with the above-mentioned low boiling point organic compounds. Other low-boiling halogenated hydrocarbons include halogenated hydrocarbons that do not contain fluorine atoms, such as methylene chloride, and fluorine-containing halogenated hydrocarbons other than those mentioned above. Furthermore, examples of the inert gas include air and nitrogen. When using these other blowing agents, the ratio of the blowing agent of the present invention to the total blowing agents is 2.
It is preferably 0% by weight, particularly 40% by weight or more.

2 active hydrogen-containing functional groups that can react with incyanate 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 waterline 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. Polyester polyols include polyhydric alcohol-polycarboxylic acid condensation polyols and cyclic ester ring-opening polymer polyols, and polyhydric alcohols include ethylene glycol, propylene glycol,
These include diethylene glycol, dipropylene glycol, glycerin, trimedylolbroban, 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 10,000. 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 rsorcinol. Further, the formaldehyde is not particularly limited, but formalin and paraformaldehyde are preferred, and the hydroxyl value of the polyol or active hydrogen compound is often selected from about 20 to 100 units 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
) 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. Furthermore, foam stabilizers are often used to form good foam. Examples of the foam stabilizer include silicone foam stabilizers and heavy fluorine compound foam stabilizers. Other additives that can be used immediately include fillers, stabilizers, colorants, flame retardants, and the like.

Using these raw materials, we produce polyurethane foam, urethane-modified polyisocyanerate foam, microcellular polyurethane elastomer, microcellular polyurethane urea elastomer, and microcellular polyurea elastomer.

Stomer and other foamed synthetic resins are obtained.

Polyurethane foams can be roughly divided into rigid polyurethane foams, semi-rigid polyurethane foams, and flexible polyurethane foams.The present invention focuses on rigid polyurethane foams and urethane-modified polyisocyanurate foams, which are fields in which halogenated hydrocarbon blowing agents are used in particular. It is particularly useful in the production of foam and other rigid foams. Among these, can it be obtained by using a polyol or a polyol mixture having a hydroxyl value of 200 to 1000 and an aromatic polyisocyanate compound? i! It is particularly useful in the production of M polyurethane foams. When producing these hard foams, the amount of halogenated hydrocarbon blowing agent used in the present invention is 5 to 1% per active hydrogen compound.
50% by weight, especially 20-60% by weight, is suitable.

In addition, at the same time, θ~
It is preferred to use 10% by weight, especially 1 to 5% by weight. On the other hand, in the case of flexible polyurethane foam, semi-rigid polyurethane foam, and microcellular elastomer, the halogenated hydrocarbon blowing agent in the present invention is preferably used in an amount of 5 to 150% by weight based on the active hydrogen compound.

In the case of soft urethane foam and semi-rigid urethane foam, it is preferable to use water in an amount of 0 to 10% by weight, and in the case of microcellular elastomer, it is preferable to use water in an amount of 0 to 5% by weight.

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

[Example] Foaming evaluation of the halogenated hydrocarbon blowing agent in the present invention was conducted for the following polyols.

Polyolumi: A polyether polyol with a hydroxyl value of 420 made by reacting glycerin with propylene oxide Polyol B: A polyether polyol with a hydroxyl value of 450 made by reacting sucrose with propylene oxide and ethylene oxide Polyol C: Propylene oxide with toluene diamine The foaming evaluation of polyether polyol having a hydroxyl value of 440 was carried out as follows. For 100 parts by weight of polyol, silicone foam stabilizer (Shin-Etsu Chemical ■ trade name)
2 parts of F-338), 1 part of water, the necessary amount of N,N-dimethylcyclohexylamine as a catalyst to give a gel time of 45 seconds, an appropriate amount of a mixture of the following blowing agents and polymethylene polyphenylisocyanate ( MD Kasei Dept. trade name PAPI 135) was mixed at a liquid temperature of 20°C, and 200mm
The mixture was placed in a wooden box measuring 20 hm x 200 mm and foamed for evaluation. The amount of foaming agent used was adjusted so that the core density of the foam was 30±2 kg/a'.

The appearance and compressive strength of the obtained foam were compared with those using R-11, and the following judgments were made.

■ R-11 ■ Dichloromethane ■ Dichloromethane 76.5% by weight 2-Methylbutane 23.5% by weight ■ R-1150% by weight Dichloromethane 38.25% by weight 2-Methylbutane 11.75% by weight The results are shown in Table 1.

The criteria for judgment are as follows.

Q: Equivalent to or better than R-11 Δ: Slightly inferior to R-11 It is possible to produce foamed synthetic resin.

Procedural amendment May S◇day, 1999

Claims (1)

[Claims] 1. A foamed synthetic resin produced by reacting an active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with isocyanate with a polyisocyanate compound in the presence of a low-boiling halogenated hydrocarbon foaming agent. 1. A method for producing a foamed synthetic resin, comprising using dichloromethane and a hydrocarbon having a boiling point of 100° C. or less as a blowing agent in combination. 2. Dichloromethane as a blowing agent and a boiling point range of 10 to 5
The method according to claim 1, wherein a hydrocarbon having a temperature of 5° C. is used in combination. 3. The method according to claim 1, wherein the weight ratio of hydrocarbon to the total weight of dichloromethane and hydrocarbon used is 2 to 95%. 4. As a hydrocarbon used in combination with dichloromethane, Part 5
2. The method according to claim 1, wherein 0% by weight or more of the hydrocarbon is composed of a compound having 5 or 6 carbon atoms. 5. The method according to claim 4, wherein the hydrocarbon used in combination with dichloromethane is n-pentane or 2-methylbutane.