Linear polyether-polysiloxane copolymers, their preparation and use

A linear polyether-polysiloxane copolymer in which linear polyether and linear polysiloxane units are linked via Si—C bonds, and which conforms to the general formula

• A(BC)nBA (I),
• in which n is ≧1, and
• A is a group of the general formula
• R1—O—[CH2CH2O]a[CH2CH(CH3)O]b[CH2CH(CH2CH3)O]c—(CmH2m)— (II),
• where R1 independently of one another is either hydrogen, alkyl, aralkyl, aryl or an R2—C(O)— radical, and R2 is a substituted or unsubstituted alkyl radical having from 1 to 8 carbon atoms, m is an integer between 3 and 8, and a, b and c independently of one another are integers between 0 and 200, with the proviso that the sum (a+b+c) is from 2 to 300,
• B is a group of the general formula
• —(R32Si—O)d—R32Si— (III),
• where R3 independently of one another are substituted and/or unsubstituted, saturated and/or unsaturated hydrocarbon radicals having from 1 to 20 carbon atoms, and d is an integer between 1 and 400,
• and C is a group of the general formula
• —(CmH2m)—O—[CH2CH2O]a[CH2CH(CH3)O]b[CH2CH(CH2CH3)O]c—(CmH2m)— (IV),
• where m, a, b and c have the values given above.