JPH05230268A - Production of synthetic resin foam - Google Patents

Abstract

PURPOSE:To produce the title foam without the fear of ozone layer depletion by reacting an active hydrogen compd. with a polyisocyanate in the presence of a blowing agent comprising a mixture of difluoromethane and chloropentafluoroethane. CONSTITUTION:An active hydrogen compd. having at least two isocyanate- reactive active hydrogen groups (e.g. a polyester polyol) and a polyisocyanate (e.g. tolylene diisocyanate) are reacted in the presence of a low-boiling halogenated hydrocarbon blowing agent comprising a mixture of difluoromethane and chloropentafluoroethane to give the title foam. An azeotropic mixture comprising 48.2wt.% difluoromethane and 51.8wt.% chloropentafluoroethane is pref. The foam has properties equivalent or superior to those of the conventional synthetic resin foam obtd. by using ozone-depleting trichlorofluoromethane, etc.

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 foam synthetic resin such as polyurethane foam, and more particularly to a method for producing a foam synthetic resin using a specific foaming agent.

[0002]

2. Description of the Related 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 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 (R11) is mainly used. Further, water is usually used together with R11. further,
When foaming is performed by the floss method or the like, dichlorodifluoromethane (R12) having a lower boiling point (gaseous under normal temperature and normal pressure) is used together with them.

Further, various other chlorofluorohydrocarbons having relatively low boiling points (hereinafter referred to as CFC freon) have been proposed as a foaming agent, but they have not been widely used except R11 and R12. It has also been proposed to use a low boiling halogenated hydrocarbon-based blowing agent such as dichloromethane instead of the CFC freon blowing agent.

[0006]

CFC freon containing chlorine atoms, such as R11 and R12, which has been widely used in the past, has a long life in the troposphere and diffuses to reach the stratosphere.
Here, chlorine radicals generated by decomposition by the sun's rays cause a chain reaction with ozone and destroy the ozone layer. Therefore, instead of these conventional CFCs, hydrochlorofluorohydrocarbons (HCFCs) that do not easily destroy the ozone layer.
In addition, alternative fluorocarbons such as hydrofluorohydrocarbons (HFCs) that do not destroy the ozone layer because they do not contain chlorine atoms are being actively searched.

The present invention is a foaming synthesis using a foaming agent containing a specific HFC Freon as an essential component which does not destroy the ozone layer and can be used as an alternative Freon while satisfying the excellent properties of the conventional CFC Freon. An object is to provide a method for producing a resin.

[0008]

The present invention provides a polyisocyanate compound and an active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group in the presence of a low-boiling halogenated hydrocarbon blowing agent. In the method for producing a foamed synthetic resin by reacting, a mixture of difluoromethane and chloropentafluoroethane is used as a low-boiling halogenated hydrocarbon-based blowing agent, which is a method for producing a foamed synthetic resin.

In the present invention, it is important to use a mixture of difluoromethane of HFC Freon and chloropentafluoroethane as the foaming agent, and the mixing ratio is not particularly limited, but preferably 30 to 30% of difluoromethane. 90 wt%, chloropentafluoroethane 70-
1 wt%, and particularly preferably, difluoromethane and chloropentafluoroethane are 48.2 wt%: 5.
1.8 wt% azeotrope (R504).

The foaming agent used in the method for producing a foamed synthetic resin of the present invention contains difluoromethane of HFC Freon which does not destroy the ozone layer, has the same characteristics as conventional CFC Freon, and can be used in the same manner as in the prior art. There are advantages such as not requiring major changes.

If necessary, other components may be further added to and mixed with the foaming agent of the present invention. For example, water, or propane, butane, pentane, isopentane,
Addition components such as hydrocarbons such as hexane, isohexane, neohexane, heptane, isoheptane, 2,3-dimethylbutane, cyclopentane, halogenated hydrocarbons such as chloromethane and dichloromethane, ethers such as isopropyl ether, etc. More than one species can be added as appropriate.

Further, R11, R12, 1,1,2-trichloro-1,2,2-trifluoroethane (R11
3), 1,2-dichlorotetrafluoroethane (R11
4), CFC freon such as monochloropentafluoroethane (R115), or 2,2-dichloro-1,1,
1-trifluoroethane (R123), 1,2-dichloro-1,1,2-trifluoroethane (R123a),
1,1-dichloro-1-fluoroethane (R141
b), 3,3-dichloro-1,1,1,2,2-pentafluoropropane (R225ca), 1,3-dichloro-1,1,2,2,3-pentafluoropropane (R2
25cb), 3-chloro-1,1,2,2-tetrafluoropropane (R244ca), 1-chloro-1,2,
2,3-tetrafluoropropane (R244cb), 3
-Chloro-1,1,2,2,3-pentafluoropropane (R235ca), 1,1-dichloro-1,2,2-
HCFC such as trifluoropropane (R243cc)
One or more of CFCs or the like can be used alone or in combination with the above-mentioned additive components in the mixture of difluoromethane and chloropentafluoroethane of the present invention.

The active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group is, for example, a compound having two or more active hydrogen-containing functional groups such as a hydroxyl group and an amino group, or two or more kinds of the compounds. A mixture may be mentioned. 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.

The compound having two or more hydroxyl groups is
Widely used polyols are preferred, but compounds having two or more phenolic hydroxyl groups, such as phenol resin initial condensates, can also be used. As a polyol,
Examples thereof include polyether polyols, polyester polyols, polyhydric alcohols, hydroxyl group-containing diethylene polymers, and the like. In particular, it is preferable to use at least one type of polyether polyol, or to use it as a main component in combination with a polyester polyol, polyhydric alcohol, polyamine, alkanolamine, or other active hydrogen compound.

The polyether-based polyol is preferably a polyether-based polyol obtained by adding a cyclic ether, particularly an alkylene oxide such as propylene oxide or ethylene oxide, to a polyhydric alcohol, a saccharide, an alkanolamine, or another initiator. 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 alcohol / polyhydric carboxylic acid condensation type polyols and cyclic ester ring-opening polymerization type polyols. Polyhydric alcohols include, for example, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol. , Glycerin, trimethylolpropane, pentaerythritol, diethanolamine, triethanolamine and the like.

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 this resol-type initial condensate There are a benzylic type initial condensate reacted in a non-aqueous system 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 initial condensates is preferably selected from the range of about 200 to 10,000.

In the above description, the term "phenols" refers to those in which one or more carbon atoms of the skeleton having a benzene ring are directly bonded to a hydroxyl group, and those having other substituted bonding groups in the same structure are also included. 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 the mixture thereof is often selected from the range of about 20 to 1000 according to 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 polyisocyanate obtained by modifying them. Can be illustrated. Specifically, for example, tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate (common name: crude MDI), xylylene diisocyanate,
Examples thereof include polyisocyanates such as isophorone diisocyanate and hexamethylene diisocyanate, and their prepolymer-type modified products, nurate modified products, and urea modified products.

When reacting the active hydrogen compound and the polyisocyanate compound, it is usually necessary to use a catalyst. Examples of the catalyst include metal compound-based catalysts such as organotin compounds and tertiary amine catalysts such as triethylenediamine that accelerate the reaction between the active hydrogen-containing group and the isocyanate group. Further, a multimerization 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. As the foam stabilizer, for example,
Examples include silicone type foam stabilizers and fluorine-containing compound type foam stabilizers. In addition, as a compounding agent that can be optionally used,
Examples include fillers, stabilizers, colorants, flame retardants and the like.

Using these raw materials, polyurethane foam, urethane-modified polyisocyanurate 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 in the production of 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 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, or microcellular elastomer, it is preferable to use the foaming agent in the present invention in an amount of about 5 to 150% by weight based on the active hydrogen compound. In the case of a flexible urethane foam or a semi-rigid urethane foam, it is preferable to use water in an amount of about 0 to 10% by weight, and in the case of a microcellular elastomer, to use water in an amount of about 0 to 5% by weight.

[0028]

[Example] Silicone-based foam stabilizer (Shin-Etsu Chemical Co., Ltd .: trade name F-338) to 100 parts by weight of various polyols 2
Parts by weight, 1 part by weight of water, a necessary amount of N, N-dimethylcyclohexylamine as a catalyst so that the gel time is 45 seconds, and a predetermined amount of the foaming agent R504 (the core density of the foam is 30 ± 2 kg / m 3 Solution) and polymethylene polyphenylisocyanate (MD Kasei Co., Ltd .: trade name PAPI1315) at a liquid temperature of 20 ° C.
And mixed in, and put into a wooden box of 200 mm × 200 mm × 200 mm to foam.

In order to evaluate the blowing agent of the present invention,
Using R11 as a foaming agent, foaming was carried out in the same manner for comparison. The criteria for evaluation are as follows. ◯: Equal to or higher than R11. Δ: Slightly inferior to R11. X: Inferior to R11. Table 1 shows the evaluation results including the compatibility between the foaming agent of the present invention and the polyol.

[0030]

[Table 1]

In Table 1, A is a polyether polyol having a hydroxyl value of 420 obtained by reacting glycerin with propylene oxide, B is a polyether polyol having a hydroxyl value of 450 obtained by reacting sucrose with propylene oxide and ethylene oxide, and C is toluenediamine. Shows a polyether polyol having a hydroxyl value of 440 obtained by reacting propylene oxide with.

[0032]

EFFECTS OF THE INVENTION According to the present invention, a good synthetic resin foam can be produced without substantially using chlorofluorohydrocarbons such as R11 which may damage the ozone layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ginko Uemura 10 Goi Kaigan, Ichihara City, Chiba Prefecture Asahi Glass Co., Ltd.Chiba Plant (72) Inventor Kenro Kitamura 1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa Asahi Glass Co., Ltd. In-house

Claims (2)

[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 low-boiling halogenated hydrocarbon blowing agent. The method for producing a foamed synthetic resin, characterized in that a mixture of difluoromethane and chloropentafluoroethane is used as the low-boiling halogenated hydrocarbon-based foaming agent. 2. The method of claim 1 wherein the blowing agent is a 48.2 wt%: 51.8 wt% azeotrope of difluoromethane and chloropentafluoroethane.