| 摘要 |
A low-tack, non-cell filling filling medium for telecommunication cables comprises in parts (by weight):- (a) 70-98% of a hydrocarbon base; (b) 1 - 15% of a block copolymer which comprises at lease one block tending to confer solubility in the base and at least one block tending to inhibit such solubility, the proportions of the blocks being such that the polymer shows a strong tendency to form a gel with the base; and (c) 1 - 15% of a hydrocarbon material that is miscible with the medium at high temperatures but forms solid dispersed particles on cooling at a temperature not lower than 65 DEG C: the base (a) comprising: (i) 0 - 95% of a mineral oil with or without wax, for example in the form of petroleum jelly; and (ii) 5 - 100% of a hydrocarbon or hydrocarbon mixture whose molecules are substantially incapable of diffusing into polyethylene, polypropylene or other cellular insulating material at temperatures of up to 80 DEG C and, when mineral oil is present being soluble in it and having a low enough (number average) molecular weight to reduce significantly the osmotic pressure of the medium. |
