Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1991-03-11
1992-09-15
Welsh, Maurice J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521157, 521164, 521167, 521168, 521169, 521170, 521172, 521173, 521174, 521176, 528 71, C08G 1814
Patent
active
051478986
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing a rigid foam. Particularly, it relates to a process for producing a rigid foam characterized by the use of a certain specific active hydrogen compound.
BACKGROUND ART
It has been widely practiced to produce a rigid foam by reacting an active hydrogen compound having at least two active hydrogen-containing groups reactive with isocyanate groups, with a polyisocyanate compound in the presence of a catalyst and a blowing agent. As the active hydrogen compound, a polyhydroxy compound or a polyamine compound may, for example, be mentioned. Various compounds are known as blowing agents for producing rigid foams. However, trichlorofluoromethane (R-11) is mainly used. Further, it is common to use water together with R-11. Further, in a case where foaming is conducted by e.g. a floss method, dichlorodifluromethane (R-12) having a lower boiling point (gaseous under atmospheric pressure at room temperature) is used together with them. Further, various proposals have been made to the effect that chlorinated fluorohydrocarbons having relatively low boiling points can be used as blowing agents, but none of them has been widely used except for the above mentioned R-11 and R-12. Further, it has been proposed to use instead of the chlorinated fluorohydrocarbon blowing agents other halogenated hydrocarbon blowing agents having low boiling points, such as methylene chloride.
A chlorinated fluorohydrocarbon which is extremely stable in the atmosphere such as R-11 or R-12 which has been widely used, is believed to reach the ozone layer located at the upper part of the atmosphere without being decomposed and then be decomposed by the action of e.g. ultraviolet rays, and the decomposed product is suspected to destroy the ozone layer. Part of such a chlorinated fluorohydrocarbon used as a blowing agent leaks into the atmosphere. Therefore, it is presumed that its use constitutes part of the cause of the destruction of the ozone layer. Accordingly, it has been required to reduce the amount of use of a blowing agent of such chlorinated fluorohydrocarbon type, or to replace it by other blowing agents.
As other blowing agents, halogenated hydrocarbons having hydrogen atoms, such as chlorinated fluorohydrocarbons having hydrogen atoms or fluorohydrocarbons having hydrogen atoms, have been proposed. However, if a halogenated hydrocarbon having hydrogen atoms is used, the initial strength of the resin during the production of a rigid polyurethane foam tends to substantially decrease, and the properties for a heat shielding material as one of the main uses of the rigid polyurethane foam, tend to be poor. Therefore, it is strongly desired to establish a technique to produce a rigid foam having high performance using a halogenated hydrocarbon having hydrogen atoms.
DISCLOSURE OF INVENTION
The present invention has been made to solve the above mentioned problems and provides a process for producing a rigid foam by reacting an active hydrogen compound and a polyisocyanate compound in the presence of a halogenated hydrocarbon blowing agent and an assisting agent such as a catalyst, characterized in that the whole or part of the active hydrogen compound is an active hydrogen compound containing in its molecular structure a group of a neutralized salt or an alkoxide.
The active hydrogen compound in the present invention comprises one or more compounds having at least two hydroxyl groups, primary amino groups, secondary amino groups, carboxyl groups or other active hydrogen groups reactive with isocyanate groups. And, at least part thereof is an active hydrogen compound containing in its molecular structure a group of a neutralized salt or an alkoxide. The main portion of the active hydrogen compound is preferably a polyol. The details of the active hydrogen compound will be described hereinafter.
In the present invention, the active hydrogen compound containing in its molecular structure a group of neutralized salt, is an active hydrogen compound having in its molec
REFERENCES:
patent: 3988268 (1976-10-01), Dietrick et al.
patent: 4133943 (1990-01-01), Blahsk et al.
patent: 4282330 (1981-08-01), Austin
Asahi Glass Company Ltd.
Welsh Maurice J.
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