Non-yellowing textile softening process in which a composition comprising a polyorganosiloxane is used

A process for the preparation of linear polyorganosiloxane of formula (V):

• ##STR28## in which:
• R is identical or different and is a monovalent radical selected from linear or branched alkyls having from 1 to 4 carbon atoms, the phenyl radical or the 3,3,3-trifluoropropyl radical;
• the symbol V represents:
• a linear or branched alkyl radical having from 5 to 20 carbon atoms;
• a radical of formula --(CH.sub.2).sub.P --COO--R.sup.12 in which p represents a number from 5 to 20 and R.sup.12 represents a linear or branched alkyl radical containing 1 to 12 carbon atoms;
• or a radical of formula --(CH.sub.2).sub.q --O--R.sup.13 in which q represents a number from 3 to 10 and R.sup.13 represents a hydrogen atom, an ethylene oxide chain, a propylene oxide chain, a mixed ethylene oxide+propylene oxide chain or an acyl radical having from 2 to 12 carbon atoms;
• Z represents a residue containing (a) sterically hindered piperidyl group (s) selected from the group consisting of:
• the residues of formula:
• ##STR29## in which:
• R.sup.1 -is a divalent radical selected from the group consisting of:
• linear or branched alkylene radicals having from 2 to 18 carbon atoms;
• alkylenecarbonyl radicals in which the linear or branched alkylene part contains 2 to 20 carbon atoms;
• alkylenecyclohexylene radicals in which the linear or branched alkylene part contains from 2 to 12 carbon atoms and the cyclohexylene part contains an --OH group and optionally 1 or 2 alkyl radicals having from 1 to 4 carbon atoms;
• radicals of formula --R.sup.4 --O--R.sup.5 --, in which the radicals R.sup.4 and R.sup.5, which are identical or different, represent alkylene radicals having 1 to 12 carbon atoms;
• radicals of the formula --R.sup.4 --O--R.sup.5 -- in which the radicals R.sup.4 and R.sup.5 have the meanings indicated above and one of them or both are substituted by one or two --OH group(s);
• radicals of formulae --R.sup.4 --COO--R.sup.5 and --R.sup.5 --OCO--R.sup.5 -- in which R.sup.4 and R.sup.5 have the meanings above;
• radicals of formula --R.sup.6 --O--R.sup.7 --O--CO--R.sup.8 -- in which R.sup.6, R.sup.7, R.sup.8, which are identical or different, represent alkylene radicals having from 2 to 12 carbon atoms and the radical R.sup.7 is optionally substituted by a hydroxyl group;
• U-represents --O-- or --NR.sup.9 --, R.sup.9 being a hydrogen atom or a linear or branched alkyl radical having from 1 to 6 carbon atoms;
• R.sup.2 are radicals, which are identical or different, selected from the group consisting of linear or branched alkyl radicals having from 1 to 3 carbon atoms and the phenyl radical;
• R.sup.3 represents a hydrogen atom or the radical R.sup.2 ;
• and those of formula:
• ##STR30## in which R'.sup.1 -is selected from the group consisting of a trivalent radical of formula ##STR31## wherein m represents a number from 2 to 20, and a trivalent radical of formula:
• ##STR32## where n represents a number from 2 to 20 U'-represents --O-- or --NR.sup.11 --, R.sup.11 being a hydrogen atom or a linear or branched alkyl radical having from 1 to 6 carbon atoms;
• R.sup.2 and R.sup.3 have the same meanings as those given with respect to the formula (II);
• the symbol Y represents a monovalent radical chosen from the radicals R, Z, V and X, the radical X being selected from an hydroxyl group or a linear or branched alkoxy radical having from 1 to 3 carbon atoms;
• the symbols R.sup.14 are identical or different and represent a monovalent radical selected from the group consisting of a radical R and a radical X such as defined hereinabove with respect to the formula (V);
• r, s and t are equal to zero or represent integers or fractional numbers greater than 0, with the additional condition according to which, if r=0, at least one of the two radicals Y represents the radical Z, and s=0;
• comprising the steps of reacting in suitable proportions, optionally in the presence of a basic catalyst, the following reactants:
• a hydrolysable silane of formula:
• (R).sub.g (X').sub.3-g SiZ (VII)
• in which the symbols R and Z have the meanings given hereinabove for the formula (V), g is a number selected from the group consisting of 0, 1 and 2 and the symbol X' represents a linear or branched alkoxy group having from 1 to 3 carbon atoms;
• a polydiorganosiloxane corresponding to the formula (V) where r=0, s=0, t=10-500, R.sup.14 is R and Y is CH, and/or a cyclic polydiorganosiloxane of formula:
• ##STR33## in which:
• R are identical or different and represent a monovalent hydrocarbon radical chosen from linear or branched alkyl radicals having from 1 to 4 carbon atoms, the phenyl radical and the 3,3,3-trifluoropropyl radical;
• u is an integer or fractional number ranging from 3 to 10;
• and optionally a chain-terminating agent consisting of a compound of formula (V) where r=0, s=0, t=0-50, R.sup.14 is R and Y is R or Z.