Silicone-based synthetic fiber finishing agent

A silicone-based agent for finishing synthetic fibers which comprises:

• (A) 100 parts by weight of an organopolysiloxane of a substantially linear molecular structure having a viscosity in the range from 100 to 1,000,000 centistokes at 25.degree. C. represented by the general formula
• XO--(--SiR.sub.2 --O--).sub.m --(--SiZR--O--).sub.n --X,
• in which R is a monovalent hydrocarbon group or a monovalent hydrocarbon group substituted by halogen atoms having 1 to 20 carbon atoms, Z is an amino-substituted monovalent hydrocarbon group represented by the general formula
• --R.sup.1 --(--NH.sub.2 --CH.sub.2 --CH--).sub.a --NR.sup.2.sub.2,
• R.sup.1 being a divalent hydrocarbon group having 1 to 10 carbon atoms, R.sup.2 being a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms and the subscript a being a positive integer of 1 to 4, X is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms and the subscripts m and n are each a positive integer with the proviso that the molar ratio of the silicon atoms having the amino-substituted hydrocarbon groups denoted by Z to all of the siliconatoms in a molecule is in the range from 0.01% to 1%;
• (B) from 1 to 50 parts be weight of an epoxy-containing alkoxy silane compound;
• and
• (C) from 1 to 50 parts by weight of an epoxy-containing organic compound, which is free from silicon.