Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1994-09-29
1995-06-13
Foelak, Morton
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C08J 910
Patent
active
054243378
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to new foaming agents for polymers and to their application to the production of synthetic foams whose manufacture and/or use does not harm the ozone layer of the atmosphere.
Phenol-aldehyde foams, and more particularly phenol-formaldehyde foams, at present find increased utilisations in the building field and in the transportation industry because of their high thermal insulation and fire resistance. They are also employed in the form of blocks for domestic use, such as flower arrangement foams.
Other synthetic polymers find large-volume applications in the form of foams, such as, for example, polyurethanes, polystyrene, styrene-maleic anhydride copolymers, polyisoprene, polybutadiene, polyvinyl chloride, vinyl chloride-vinyl acetate, vinyl chloride-ethylene, vinyl chloride-vinylidiene [sic] chloride and vinyl chloride-acrylonitrile copolymers, polyethylene, polypropylene, tetrafluoroethylene-hexafluoropropylene copolymers, ethylene-vinyl acetate and ethylene-butyl acrylate copolymers, graft copolymers of vinyl chloride and alkyl acrylate, polyamides and polylactams.
These polymer foams, such as phenol-aldehyde foams, have in common the fact that their manufacture generally makes use, as blowing agent, of one or a number of completely halogenated hydrocarbons, especially chlorofluorocarbons known as CFCs. At the present time the use of chlorofluorocarbons (CFCs) presents serious ecological problems. In fact, these products are suspected of destroying the stratospheric ozone layer, and this can result in a greater penetration of solar UV rays and, consequently, considerable physiological disorders in living beings.
The CFCs are employed in particular for the manufacture of synthetic foams. Replacement of the CFCs by a less harmful gas represents a considerable ecological step forward. The solution most commonly adopted hitherto consists in replacing the CFCs with hydrochlorofluorocarbons (HCFCs). These products have been deliberately chosen for their greater instability, so as to be capable of decomposing before reaching the stratosphere. However, the environmental impact of these compounds remains so far unknown.
The problem which the present invention is intended to solve consists in providing a simple, economical and efficacious means for protecting the ozone layer of the atmosphere in the course of the manufacture and use of polymer foams. In the more particular context of phenol-aldehyde foams, a second problem which the present invention is intended to solve consists in developing a formulation capable of completely filling the mould employed in the course of this manufacture and capable of expanding during a short period while retaining the good thermal and acoustic insulation properties which are traditional in phenol-aldehyde foams.
These objectives are attained by virtue of the present invention by means of a foamable composition comprising a mixture based on polymer resin and an effective quantity, in relation to the said resin, of blowing agent, the said composition being characterised in that the blowing agent comprises at least one .alpha.,.beta.-hydroxylated hydrocarbon azide. An .alpha.,.beta.-hydroxylated hydrocarbon azide within the meaning of the present invention is intended to mean a compound of general formula ##STR1## in which R.sup.1, R.sup.2 and R.sup.3 which are identical or different, are chosen from the hydrogen atom and alkyl, aryl, aralkyl, alkylaryl and cycloalkyl radicals preferably containing up to 20 carbon atoms, to 20 carbon atoms, and
The synthesis of such compounds has already been described in the literature, for example by addition of sodium azide to an oxirane of formula ##STR2## in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4 have the meanings shown for the formula (I). Another known method of synthesis according to the literature consists in the addition of sodium azide to the compound of formula C.sub.6 H.sub.5 -CO-CH.sub.2 Br, followed by a reduction stage to obtain 2-azido-1-phenylethanol of formula C.sub.6 H.sub.5 -CHOH-CH.sub.2 N.
REFERENCES:
patent: 2764599 (1956-06-01), Clifford et al.
patent: 2930769 (1960-03-01), Haggis et al.
patent: 4772640 (1988-09-01), Wolf et al.
Bedel Didier
Crozat Chantal
Cray Valley SA
Foelak Morton
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