Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1990-12-21
1993-01-26
Welsh, Maurice J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521107, 521108, 521131, C08G 1814
Patent
active
051823098
DESCRIPTION:
BRIEF SUMMARY
The present invention is related to a polyurethane foam material (hereinafter referred to as PUR foam material) having a particularly uniform cellular foam structure, the pores whereof being free of halogenated hydrocarbon compounds. Such halogenated hydrocarbon compounds, in particular the fully halogenated chlorofluorocarbons or CFC have been used in the prior art processes as foaming agents. The present invention is further related to processes for producing such PUR foam materials where no halogenated hydrocarbons are used as foaming agent.
PUR foam materials are used in large amounts for the most varying purposes, for instance for cushions, as intermediary layers to be placed under carpets, in upholstered furniture, for packaging purposes, as isolating material in houses or in freezing furniture. There are produced soft foams, medium rigid foams and rigid foams from PUR. In general, soft foams are produced using carbon dioxide as foaming agent. Carbon dioxide is produced in the reaction between the diisocyanates started from and water added to the reaction mix. Some of the soft foams however are also produced by means of CFCs as foaming agent. Solid foams are mostly produced with CFCs as foaming agent. CFCs as foaming agent are used in large amounts. Substantial amounts of the foaming agent escape during production or is liberated when foam pore walls are broken during the use of the PUR foam material. The CFCs as foaming agent produce desirable results in many respects. They provide in the produced PUR foam material desirable non-inflammability properties. Furthermore, the PUR foam materials produced with these foaming agents have further desirable physical properties such as in particular a low heat conductivity, expressed in low lambda values, as they are most desired in the production of furnitures for living homes, in cushions and in the construction of living homes and of other houses. Thus, the PUR foam materials produced with these foaming agents may be classified into very desired heat conductivity groups which are most desirable for various fields of use of the foam materials. By the addition of further flame retardants to the mixture of the starting components the flame retardant properties of the resulting PUR foam materials may be further increased until the fire retardant reaches classes B2 and B1. Since PUR foam materials are produced by foaming liquid starting components, the use of CFCs or water results in a very uniform cell structure with a low volume weight of the resulting material. This allows a simple foaming of the material in molds or on a continuous conveyer belt. This latter procedure is particularly applied for producing isolating sheets from PUR solid foams as they are used in buildings and the like constructions. This procedure further allows the production of the PUR foam material with a solid sheet material on both sides of the foam sheet from a flexible or rigid material, thus producing a foam sandwich structure.
However, under enviromental aspects it is most disadvantageous in this desirable material and its production that for the foaming of such materials, in particular of PUR rigid foam materials, there are used almost solely chlorofluorocarbons (CFCs) as foaming agent and that theses CFCs show a highly negative effect to the ozone layer in the atmosphere of the globe as ozone-depleting material. Therefore, the use of such foaming agents is not at all desirable and is even forbidden in many countries. For several years substantial research has been done to partly or even completely substitute the CFCs as foaming agent in view of their undesirable ozone-depleting properties.
For instance tests have been made in the production of PUR soft foam materials to combine the known addition of water to the used starting material containing isocyanate together with other features such that carbon dioxide is used as additional or main foaming agent, thus lowering or even avoiding the undesired release of the hazardous CFCs. However, such procedures have deleterious effects to
REFERENCES:
patent: 3189565 (1965-06-01), Woods et al.
patent: 3509076 (1970-04-01), Anderson
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