JPH07109325A - Production of foamed synthetic resin - Google Patents

Abstract

PURPOSE:To produce a foamed synthetic resin without using specific fluorocarbons being in fear of the degradation of the ozone layer. CONSTITUTION:In this method for producing a foamed synthetic resin by reacting an active hydrogen compound with a polyisocyanate compound in the presence of a foaming agent and a catalyst, a 2-8C hydrocarbon, e.g. cyclohentane and water are used as the foaming agents and a polyol obtained by subjecting amines such as ethylene diamine to cyclization polymerization reaction with an alkylene oxide is used as an active hydrogen compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foamed synthetic resin such as polyurethane foam, and more particularly to a method for producing a foamed synthetic resin using a specific foaming agent.

[0002]

2. Description of the Related Art 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 catalyst and a foaming agent. It is widely practiced.

Examples of active hydrogen compounds include polyhydroxy compounds and polyamine compounds. 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, microcellular polyurea 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.
In addition, water is usually used together with R-11. Further, when foaming is performed by the floss method or the like, dichlorodifluoromethane (R-12) having a lower boiling point (a gas under normal temperature and normal pressure) is used together with them.

[0005]

The 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, reach the ozone layer above the atmospheric layer without being decomposed. Then, it was thought that the decomposition products would be destroyed by the action of ultraviolet rays and the decomposition products would destroy the ozone layer.

Since some of the above-mentioned chlorinated fluorinated hydrocarbons used as a foaming agent leak into the atmosphere, there is a fear that their use may be a cause of ozone layer depletion. Has been done. 1,1-Dichloro-2,2,2-, which is considered to be less dangerous because it has a hydrogen atom in its molecule and decomposes before reaching the ozone layer above the atmosphere.
Trifluoroethane (R-123), 1,1-dichloro-1-fluoroethane (R-141b), monochlorodifluoromethane (R-22) and the like have been proposed as a foaming agent and are widely used. The substance also has an ozone depletion potential and cannot be an essential solution. Therefore, in place of such chlorinated fluorinated hydrocarbons, it is desired to develop a foaming agent that does not cause ozone layer depletion and a foaming synthetic resin manufacturing technique.

Hydrocarbons having 2 to 8 carbon atoms are compounds having a boiling point capable of functioning as a foaming agent and having no danger of depleting the ozone layer. Ethane, propane, butane, pentane,
Compounds such as hexane, heptane, octane, and isomers of these compounds have a small contribution to global warming like other halogenated hydrocarbons as well as ozone depletion,
Although it can be used as an environment-friendly foaming agent, when it is used as a foaming agent for polyurethane foam, its solubility with an active hydrogen compound such as a polyol is extremely low, and a stable system liquid cannot be obtained. In order to use a hydrocarbon as a foaming agent, a technique for improving the solubility of the foaming agent is required without impairing the performance of the foam.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. An active hydrogen compound and a polyisocyanate compound are reacted in the presence of a foaming agent and a catalyst to produce a foamed synthetic resin. In the method, a hydrocarbon having 2 to 8 carbon atoms is used as a foaming agent, and an active hydrogen compound having a nitrogen atom and having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group is used as the active hydrogen compound. The present invention proposes a method for producing a foamed synthetic resin, characterized in that

The inventors of the present invention have made earnest studies and found that the presence of a nitrogen atom in the molecule of the active hydrogen compound can greatly improve the solubility of the hydrophilic active hydrogen compound for polyurethane foam in hydrocarbons. . To obtain an active hydrogen compound having a nitrogen atom,
For example, there is a method of ring-opening polymerizing an alkylene oxide with an amine such as an aliphatic amine or an aromatic amine.

Preferred amines include monoalkanolamines such as monoethanolamine, dialkanolamines such as diethanolamine, trialkanolamines such as triethanolamine, alkylenediamines such as ethylenediamine and propylenediamine, phenylenediamine, tolylenediamine, and xylyl. Examples thereof include aromatic amines such as diamine, and heterocyclic polyamines such as piperazine and aminoalkyl-substituted piperazine. Of these, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, tolylenediamine, and aminoethylpiperazine are particularly preferable.

The alkylene oxide used at this time is preferably one having 3 or more carbon atoms such as propylene oxide or butylene oxide. Moreover, it is preferable to use such an active hydrogen compound containing a nitrogen atom in an amount of 30% by weight or more based on all active hydrogen compounds used.

Examples of the hydrocarbon having 2 to 8 carbon atoms in the present invention include propane, butane, n-pentane, isopentane, neopentane, cyclopentane, hexane and cyclohexane. One of these may be used alone, or a mixture of two or more may be used.

The blowing agent in the present invention has 2 to 8 carbon atoms.
The hydrocarbons can be used alone or in combination with other blowing agents. In particular, water is often used together. As a foaming agent that can be used in combination with other than water,
For example, there are fluorinated halogenated hydrocarbon type foaming agents and other low boiling point halogenated hydrocarbons, low boiling point hydrocarbons, inert gases and the like.

As the fluorinated halogenated hydrocarbon containing chlorine, R-123, R-141b, R-22, 1,2-
Dichloro-1,1,2-trifluoroethane (R-12
3a), 1-chloro-1,1-difluoroethane (R-
142b), 3,3-dichloro-1,1,1,2,2-
Pentafluoropropane (R225ca), 1,3-dichloro-1,1,2,2,3-pentafluoropropane (R225cb), 3-chloro-1,1,2,2-tetrafluoropropane (R244ca), 1 -Chloro-
1,2,2,3-tetrafluoropropane (R244c
b), 3-chloro-1,1,2,2,3-pentafluoropropane (R235ca), 1,1-dichloro-1,
Freon such as 2,2-trifluoropropane (R243cc) may be used alone or in combination and appropriately used in combination with the foaming agent in the present invention. Although these compounds have an ozone depletion potential by themselves, their use amount can be reduced by using them in combination with the hydrocarbon which is the blowing agent in the present invention.

As the fluorinated hydrocarbon containing no chlorine,
R-134a, R-356mff, R-356mec,
R-356myp, R-245eb, R-245ca,
R-254fb and the like, alone or in combination,
It is also possible to use the foaming agent of the present invention in combination. Although these compounds have a global warming potential by themselves, their amount can be reduced by using them in combination with the hydrocarbon which is the blowing agent of the present invention.

Other low-boiling halogenated hydrocarbons include halogenated hydrocarbons containing no fluorine atom such as methylene chloride and fluorine-containing halogenated hydrocarbons other than the above. The inert gas may be air or nitrogen.

The active hydrogen compound in the present invention can be used alone or in combination with an active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with other isocyanate groups. The active hydrogen compound that can be used in combination is a compound having two or more active hydrogen-containing functional groups such as hydroxyl groups, or a mixture of two or more kinds of the compounds. In particular, a compound having two or more hydroxyl groups, 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, phenol resin initial condensation product) can also be used. Examples of polyols include polyether polyols, polyester polyols, polyhydric alcohols, and hydroxyl group-containing diene 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, and other active hydrogen compounds.

The polyether polyols include polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane and pentaerythritol, saccharides, other initiators, and cyclic ethers, particularly polypropylene oxide and the like. A polyether polyol obtained by adding ethylene oxide is preferable.

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 vinyl polymer are dispersed mainly in a polyether polyol. Polyester polyols include polyhydric alcohol / polycarboxylic acid condensation type polyols and cyclic ester ring-opening polymer type polyols.

As the compound having two or more phenolic hydroxyl groups, a resol-type initial condensate obtained by condensation-bonding phenols with an excess of formaldehyde in the presence of an alkali catalyst, and when synthesizing the resol-type initial condensate There are benzylic type initial condensates reacted in a non-aqueous system, and novolak type initial condensates obtained by reacting excess phenols with formaldehydes in the presence of an acid catalyst. The molecular weight of these initial condensates is preferably about 200 to 10,000.

In the above description, 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 another substituent group in the same structure. Typical examples include phenol, cresol, bisphenol A, resorcinol and the like. The formaldehydes are not particularly limited, but formalin, paraformaldehyde and the like are preferable.

The hydroxyl value of the polyol or active hydrogen compound is often selected from about 20 to 1000 depending on the purpose.

The polyisocyanate compound is an aromatic, alicyclic or aliphatic polyisocyanate having two or more isocyanate groups, a mixture of two or more thereof, and a modified poly (polyisocyanate) obtained by modifying them. There is isocyanate. Specifically, for example, tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate (usually crude M
DI), xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and other polyisocyanates and their prepolymer-type modified products,
Examples include modified nurate and modified urea.

When reacting the active hydrogen compound and the polyisocyanate compound, it is usually necessary to use a catalyst. As the catalyst, a metal compound-based catalyst such as an organotin compound or a tertiary amine catalyst such as triethylenediamine that accelerates the reaction between the active hydrogen-containing functional group and the isocyanate group can be used. Further, a polymerizing catalyst for reacting isocyanate groups such as carboxylic acid metal salt may be used depending on the purpose.

Further, a foam stabilizer for forming good bubbles is often used. Examples of the foam stabilizer include a silicone type foam stabilizer and a fluorine-containing compound type foam stabilizer. In addition, examples of the compounding agent that can be optionally used include a filler, a stabilizer, a colorant, and a flame retardant.

Using these raw materials, polyurethane foam, urethane-modified polyisocyanate foam, microcellular polyurethane elastomer, microcellular polyurethane urea elastomer, microcellular polyurea elastomer, and other foaming 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 1000 and an aromatic polyisocyanate compound.

When producing these rigid foams, the amount of the specific foaming agent used in the present invention is appropriately 5 to 150% by weight, particularly 20 to 60% by weight, based on the active hydrogen compound. At the same time, it is preferable to use water in an amount of 0 to 10% by weight, particularly 1 to 5% by weight, 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 amount of the specific foaming agent used in the present invention is
It is preferably about 5 to 150% by weight based on the active hydrogen compound. In the case of flexible polyurethane foam or semi-rigid polyurethane foam, water is added in an amount of 0 to 10% by weight,
In the case of microcellular elastomer, add 0-5 water.
It is preferable to use them together at about wt%.

[0031]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Rigid polyurethane foams were produced according to the present invention. Examples 1-2 are comparative examples, and Examples 3-6 are examples. The polyols used are as follows.

Polyol A: A polyol having a hydroxyl value of 480 obtained by subjecting sucrose to ring-opening polymerization reaction of propylene oxide and ethylene oxide. Polyol B: A polyol having a hydroxyl value of 550 obtained by subjecting glycerin to ring-opening polymerization reaction of propylene oxide and ethylene oxide. Polyol C: A polyol having a hydroxyl value of 480 obtained by subjecting ethylenediamine to ring-opening polymerization reaction of propylene oxide. Polyol D: A polyol having a hydroxyl value of 480 obtained by subjecting monoethanolamine to ring-opening polymerization reaction of propylene oxide. Polyol E: Hydroxyl number 45 obtained by ring-opening polymerization reaction of toluene oxide with ethylene oxide and propylene oxide
0 polyol.

The combinations of polyols shown in Table 1 (total 1
100 parts by weight), 1.5 parts by weight of a silicone foam stabilizer, an amine catalyst (a necessary amount for making the gel time about 65 seconds), 2 parts by weight of water as an auxiliary foaming agent, and 20 parts of cyclopentane as a foaming agent. Parts by weight were mixed. At this time, the solubility of the system was confirmed. This mixed solution and crude MDI (index 110) are mixed at a liquid temperature of 20 ° C., and 200 × 2
It was put into a wooden box of 00 × 200 mm and foamed.

The density (k) of the obtained polyurethane foam
g / m ³ ), compressive strength (kg / cm ² ) and cell shape were evaluated. The evaluation results are summarized in Table 1. However, the evaluation criteria for the solubility of the polyol system were as follows: transparent and uniform, ◯, slightly turbid, Δ, white turbid, and separated.

[0036]

[Table 1]

[0037]

EFFECTS OF THE INVENTION According to the present invention, a foaming synthetic resin having excellent physical properties can be produced by substituting a specific freon having a risk of ozone depletion with a foaming agent having a risk of ozone depletion such as a hydrocarbon.

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Claims (5)

[Claims] 1. A method for producing a foamed synthetic resin by reacting an active hydrogen compound and a polyisocyanate compound in the presence of a foaming agent and a catalyst, wherein the foaming agent has 2 to 8 carbon atoms.
Of the foamed synthetic resin, wherein the active hydrogen compound having a nitrogen atom and having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group is used as the active hydrogen compound. Production method. 2. An active hydrogen compound having a nitrogen atom and having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group is monoethanolamine, ethylenediamine,
The production method according to claim 1, which is a polyether polyol obtained by ring-opening polymerization of an alkylene oxide with an amine selected from toluenediamine, triethanolamine, diethanolamine and aminoethylpiperazine. 3. The method according to claim 2, wherein the alkylene oxide has 3 or more carbon atoms. 4. An active hydrogen compound having a nitrogen atom and having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group is used in an amount of 30% by weight or more based on the total active hydrogen compounds. Production method. 5. The method according to claim 1, wherein the hydrocarbon having 2 to 8 carbon atoms is at least one selected from propane, butane, n-pentane, isopentane, neopentane, cyclopentane, hexane and cyclohexane.