Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1996-07-01
1998-02-17
Foelak, Morton
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521120, 521123, 521128, 521129, 521906, C08G 1810
Patent
active
057192006
DESCRIPTION:
BRIEF SUMMARY
The invention relates to flame-resistant polyurea foam, a process for its production and its use.
DE 39 09 083 C1 discloses a gypsum foam having a porous structure, containing a polyurea, which has a bulk density of from 100 to 400 kg/m.sup.3, is open-celled and contains as polyurea the condensation product of diphenylmethane 4,4'-diisocyanate prepolymers and water. The gypsum foam is to be used as sound and/or heat insulation.
A disadvantage of this process is hydraulically setting calcium sulfate hemihydrate (.alpha.-calcium sulfate; CaSO.sub.4.1/2H.sub.2 O) is to be used as starting material, because the preparation of the latter by dehydration of calcium sulfate dihydrate requires considerable amounts of energy. In the subsequent processing of the prior art (DE 39 09 083 C1, Examples 1 and 2), gypsum materials having a bulk density of above 1000 kg/m.sup.3 are obtained, so that the bulk density region of less than 100 kg/m.sup.3 (=<0.1 g/cm.sup.3) which is of interest for the most important application sector (heat insulation, acoustics) is not achieved. In addition, such materials cannot be used for the application area of sound absorption, since no cell structure is present. Likewise, there are no indications as to whether, and, if so, how the gypsum "foams" described can be made flame-resistant, which is an indispensable prerequisite for their use as building materials for heat insulation and sound absorption. The process indicated would be difficult to transfer to the industrial scale, since the mixtures obtained according to the prior art (DE 39 09 083 C1, Examples 1 and 2) have a mortar-like consistency.
Surprisingly, these problems can be solved by, according to the invention, starting out from calcium sulfate dihydrate, by using relatively large amounts of water and prepolymers of diphenylmethane 4,4'-diisocyanate to ensure that the mixtures of the starting components are pumpable or castable and by using ammonium polyphosphate as flame retardant.
Thus, addition of ammonium polyphosphate made it possible to produce open-celled and light (bulk density: <100 kg/m.sup.3) polyurea foams which met the requirements of the German Building Material Class DIN 4102-B2 if the bulk density was above 35 kg/m.sup.3 and the proportion of gypsum was over 30% by mass.
Furthermore, it was possible for the first time, by addition of ammonium polyphosphate, to produce open-celled, light (bulk density: <100 kg/m.sup.3) and fire-resistant polyurea foams which met the requirements of the German Building Material Class DIN 4102-B1. This was surprising and not foreseeable because with falling bulk density the proportion of noncombustible inorganic filler has to be reduced and the proportion of combustible polyurea has to be increased to the same extent.
A very important side effect of the use of ammonium polyphosphate as flame retardant is the better binding of the gypsum into the polyurea foam. While a gypsum-filled polyurea foam which has been produced without use of ammonium polyphosphate forms a great deal of dust during processing with partial loss of the pulverulent gypsum, in the polyurea foams of the invention the dusting is suppressed even when only small amounts of ammonium polyphosphate are used.
A BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the X-ray analysis of gypsum according to this invention.
FIG. 2 shows the X-ray analysis of another type of gypsum according to this invention.
FIG. 3 shows the X-ray analysis of plaster of paris according to this invention.
FIG. 4 shows thermogravimetric analysis of gypsum according to this invention.
FIG. 5 shows thermogravimetric analysis of another type gypsum according to this invention.
FIG. 6 shows thermogravimetric analysis of plaster of paris according to this invention.
FIG. 7 illustrates an apparatus used in the preparation of polyurea foam according to this invention.
In detail, the invention now provides a flame-resistant polyurea foam which combination with further halogen-free flame retardants and/or halogen-free synergists, of diphenylmeth
REFERENCES:
patent: 5084487 (1992-01-01), Becker et al.
patent: 5177118 (1993-01-01), Duaber et al.
patent: 5364852 (1994-11-01), Hinz et al.
Lagoda Reinhold
Staendeke Horst
Foelak Morton
Hoechst Aktiengesellschaft
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