| 摘要 |
A mixture of linear block copolymers having the general formula <FORM:0880022/IV (a)/1> in which R1 is hydrogen when attached to (CnH2nO) blocks and alkyl when attached to siloxane blocks, each R is an alkyl, alkenyl, aryl, alkaryl or aralkyl radical, x is an integer of at least 2, y is an integer of at least 5, n is 2, 3 or 4, and a and b are integers of at least 1, may be made (1) by heating a dialkoxydihydrocarbonyl siloxane and a linear polyoxyalkylene compound containing 2 reactive OH groups and at least 5 oxyalkylene units, and removing from the reaction mixture the alkanol corresponding to the alkoxy groups, (2) by condensing the diol with a dialkoxydihydrocarbonylsilane and equilibrating the product with a cyclic dihydrocarbonyl siloxane, or (3) by reacting the diol with a dihydrocarbonysiloxane containing terminal Sibonded H atoms in the presence of an alkaline catalyst, e.g. piperidine. Reaction (1), which can be conducted in the presence of a solvent, e.g. toluene or xylene, is preferably effected at 80 DEG to 200 DEG C. in the presence of a catalyst, e.g. trifluoroacetic, perfluorobutyric, perfluoroglutaric, acetic or monochloroacetic acid or potassium silanolate. After the reaction the catalyst is removed or neutralized, e.g. in the case of an acid catalyst, by adding an equivalent of a weak base, e.g. mono- or di-ethanolamine, monoisopropanolamine, dibutylamine, NaHCO3 or anhydrous NH3. The linear alkoxy-terminated siloxanes may be made by reacting a dihydrocarbonyl cyclic siloxane tri- or tetra-mer with a dialkoxysilane, and the diols can be made by reacting alkylene oxides and a diol starter, as described in Specification 651,712 and U.S.A. Specification 1,921,378. Examples are given. Uses. The water-soluble block copolymers are useful as lubricants in moulding rubber and in combination with diols as lubricants and hydraulic fluids.
|
