| 摘要 |
<p>1424290 Synthetic resin compositions BAYER AG 8 Feb 1974 [9 Feb 1973] 5863/74 Headings C3R and C3T A process for the production of a cured resin resistant to high temperatures, e.g. 400-600‹ C., comprises mixing a phenol-formaldehyde and/or cresol-formaldehyde resin with from 20- 70% wt. based on the resin mixture of a polysiloxane resin containing units selected from RSiO 3/2 , R 2 SiO 2/2 , C 6 H 5 SiO 3/2 and R 3 SiO 1/2 units where R is a C 1 -C 4 hydrocarbon radical, and curing the resulting mixture by heating preferably at 150-450‹ C., and optionally under pressure. The mixing may take place in the presence of at least one formaldehyde donor, organic and/or inorganic fillers and an organic solvent. The polysiloxane resin preferably has the following composition 70-98 mol. per cent RSiO 3/2 ; 2-20 mol. per cent R 2 SiO 2/2 ; 0-10 mol. per cent C 6 H 5 SiO 3/2 and 0-5 mol. per cent R 3 SiO 1/2 units. The phenolic resin may be prepared by reacting phenol and/or cresol with aqueous HCHO in a molar ratio of 1 : 0.6 to 1 : 1À4 in the presence of an acidic or basic catalyst. Suitable fillers include metals and/or metal oxides, calcium fluoride, asbestos, silica, butyl nitrile and/or chloroprene rubbers. Suitable formaldehyde donors are hexamethylene tetramine, trioxy- or polyoxymethylene. In the examples a mixture of a phenol-HCHO novolak resin, hexamethylenetetramine and phthalic acid anhydride is mixed with various amounts of a methyl silicone resin containing 3 mol. per cent of phenylsiloxane, in xylene and the resultant mixture is cured by heating. Uses.-Friction linings.</p> |
