Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1999-07-08
2000-10-17
Foelak, Morton
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521 98, 521181, C08J 914
Patent
active
061333328
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a process for producing a phenolic resin foam which is lightweight and excellent in heat insulation property and in flame retardancy, and more particularly to an improved process for producing a phenolic resin foam having uniform bubbles, the process being characterized by the use of a specific low-boiling organic compound-based blowing agent.
BACKGROUND ART
Rigid urethane foams can be produced in situ using spray means or the like and have been used in various fields including building field as an heat-insulating material for preventing dew condensation or the like. However, such urethane foams have a drawback of low flame retardancy. In this situation, phenolic resin foams have come into use, the foams being superior not only in flame retardancy but in heat insulation property, sound insulation property and the like. However, the phenolic resin is difficult to spray in an evenly dispersed state due to its high viscosity, and at a low temperature, the foaming reaction is hindered, giving a foam which is brittle at the surface and low in adhesion. In short, difficulties are encountered in in situ production.
Generally a phenolic resin foam is prepared as follows. A resol phenolic resin serving as a raw material is mixed with a blowing agent, a foam stabilizer, a curing agent and other additives to give a uniform composition. Then the composition is poured into a mold and expanded at an elevated temperature.
In said production of phenolic resin foams, chlorofluorocarbons are used as a low-boiling organic compound-based blowing agent, said chlorofluorocarbons having a low heat conductivity and showing high heat insulation property when enclosed with closed cells. For example, trichlorofluoromethane (CFC-11) and trichlorotrifluoroethane (CFC-113) have been chiefly used.
In recent years, however, it has been suggested that some chlorofluorocarbons, when released into the atmosphere, would deplete the stratospheric ozone layer, and would cause global warming due to greenhouse effect, thereby inflicting a serious adverse influence on the ecosystem including humans. An international agreement calls for a restriction of use of chlorofluorocarbons involving a high ozone-depleting risk. Said CFC-11 and CFC-113 are among the chlorofluorocarbons to be controlled for restriction. From this viewpoint as well, there is a need for development of novel blowing agents which are free from the ozone-depleting and global warming problems or substantially without such risks.
Of late, it was proposed to use 1,1-dichloro-1-fluoroethane and 1,1-dichloro-2,2,2-trifluoroethane as chlorofluorocarbons which would exert little influence on the ozone layer, and they have currently come into use. Yet these chlorofluorocarbons threaten us with ozone depletion none the less because they contain chlorine in the molecule. Japanese Unexamined Patent Publications Nos. Hei 2-29440 and Hei 2-235982 proposed to use chlorine-free fluorohydrocarbons free from ozone-depleting risks. Japanese Unexamined Patent Publication No. Hei 5-239251 proposed the use of 1,1,1,3,3-pentafluoropropane as a blowing agent for the production of plastic foams.
1,1,1,3,3-pentafluoropropane (HFC-245fa) which is a non-inflammable compound with a boiling point of 15.degree. C. and a hydrogen-containing fluorohydrocarbon is considered to entail little or no ozone-depleting or global warming risks.
Currently attention is directed to 1,1,1,3,3-pentafluoropropane as a promising candidate substitute for CFC-11 and CFC-113 because of its boiling point close to theirs and its non-inflammability.
DISCLOSURE OF THE INVENTION
It is a principal object of the present invention to provide a process for producing a phenolic resin foam using a blowing agent which is free of ozone-depleting risks and is unlikely to adversely affect global warming, the blowing agent being flame retardant, having a suitable boiling point, and excelling in compatibility with the raw material for a foam, the process being capable of imparting high
REFERENCES:
patent: 5250208 (1993-10-01), Merchant et al.
patent: 5696306 (1997-12-01), Ide et al.
Ide Satoshi
Shibanuma Takashi
Daikin Industries Ltd.
Foelak Morton
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