Stabilization of melamine and/or urea dispersions in polyols and

Details Stabilization of melamine and/or urea dispersions in polyols and Stabilization of melamine and/or urea dispersions in polyols and

1991-07-15

1992-10-06

Welsh, Maurice J.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Cellular products or processes of preparing a cellular...

521136, 528 52, 528 53, 528 54, 25218224, 524161, 524386, 524597, C08G 1828

Patent

active

051532336

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to the preparation of storage stable or easily redispersable melamine and/or urea dispersions in polyols, polymer polyols and blends thereof for use in the manufacture of combustion resistant polyurethane foams.
The combustibility of polyurethane foam is a well known phenomenon which now limits its use in some applications. In furniture application, the United Kingdom has adopted legislation which requires polyurethane foam to meet more rigorous combustibility standards. Most presently available foams cannot meet these standards. Consequently, there is a need for modified polyurethane foams which are less combustible than previously.
An approach to solve this problem was developed by Bridgestone (see for example GB Patent No. 1,585,750) and BASF (see for example U.S. Pat. No. 4,258,141) in the late seventies. Their solution to this problem was to incorporate melamine into the polyurethane foam during its manufacture.
The most convenient way of introducing melamine into the formulation was to first disperse it into the polyol. At this stage the melamine/polyol dispersion has to be stirred continuously or the foam manufactured immediately since melamine settles rapidly out of a polyol dispersion. Thereafter it is extremely difficult to redisperse it again. This problem was addressed by BASF in U.S. Pat. No. 4,293,657 for conventional polyether polyols. U.S. Pat. No. 4,293,657 discloses the use of a stabilizer in conjunction with very fine particle size melamine. The stabilizer used is selected from silicic acid and silicates, perfluorinated alkyl carboxylic acids and salts, fatty alcohol sulfate salts, etc. This patent teaches that 90% of the melamine should have a particle size less than 10 microns.
The approach described above has disadvantages. If done in situ, as tought in U.S. Pat. No. 4,293,657, the melamine particle size reduction is a costly, energy intensive process during which polyol degradation may occur. If not done in situ, the very fine particle sized melamine grades (90% less than 10 micron) produce inherently more stable dispersions but they are more difficult to handle and to disperse than the most common grades with an average particle size of about 50 microns. In addition, for the same melamine loading, the dispersion viscosity increases rapidly with particle size reduction.
Surprisingly, it has now been found that the presence of alkylbenzene sulphonate salts improves considerably the stability of melamine and/or urea dispersions in polyols and polymer polyols. Surprisingly it has also found also that the initial presence of alkylbenzenesulphonate salts in a dispersion allows an easy redispersion of the melamine or urea if it has settled out.
Accordingly, the present invention concerns a storage stable or easily redispersible dispersion of melamine, urea or a blend thereof in a polyol, polymer polyol or a blend thereof characterized in that the said dispersion comprises an alkylbenzenesulfonate salt as a dispersion stabilizer.
In another aspect the present invention concerns a method for preparing a storage stable or easily redispersible dispersion of melamine, urea or a blend thereof in a polyol, polymer polyol or a blend thereof wherein a dispersion stabilizer is added prior to, during or shortly after the addition of melamine, urea or a blend thereof to the polyol, polymer polyol or a blend thereof, characterized in that said dispersion stabilizer is an alkylbenzenesulfonate salt.
Still in another aspect the present invention concerns a foam produced from the storage stable or easily redispersible dispersion of melamine, urea or a blend thereof of the present invention.
Still in another aspect the present invention concerns polyurethane foams produced from the storage stable or easily redispersible dispersion of melamine, urea or a blend thereof of the present invention.
Still in another aspect the present invention concerns an aricle made from the polyurethane foam produced from the storage stable or easily redispersible dispersion of melamine, urea or a

REFERENCES:
patent: 4293657 (1981-10-01), Nissen et al.
patent: 4454254 (1984-06-01), Reichel et al.
Allinger, et al; Organic Chemistry; p. 938; 1985.

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