Patent GB-1479356-A (GB)
Title: Organosilicon compositions which impart non-stick properties to cellulosic and synthetic materials
IPC: C08J7/043
Filed: 1975-05-23
Abstract: 1479356 Anti-adhesive coatings RHONEPOULENC INDUSTRIES 23 May 1975 [10 June 1974] 22816/75 Heading B2E [Also in Division C3] Flat cellulosic or synthetic materials are provided with a non-stick coating comprising by weight: (A) 100 parts of dimethylpolysiloxane polymer which is either (i) an α, #-dihydroxydimethylpolysiloxane gum with a viscosity of at least 1 million cP at 25C, or (ii) a mixture containing at least 75% of said gum and at most 25% of low molecular weight linear and/or cyclic dimethylpolysiloxane polymers, present during the preparation of said gum by polymerisation of dimethylcyclopolysiloxane by means of an alkaline or acid catalyst, or (iii) a mixture containing 60-90% of α, #- dihydroxydimethylpolysiloxane oil with a viscosity from 300-900000 cP at 25C, and 40- 10% of α, #-bis-(triorganosiloxy)-dimethylpolysiloxane gum with a viscosity of at least 1 million cP at 25C, blocked at its chain ends by units of the formulae  and/or  (B) 0-10 parts of a methylhydrogenopolysiloxane oil of the formula  (CH 3 ) 3 SiO[Si(CH 3 ) 2 O] x [SiH(CH 3 )O] y Si(CH 3 ) 3  where x is 0-30, y is 5-90; (C) 2-10 parts of a crosslinking system comprising (1) 70-95% of at least one organosilicon compound selected from those of the formulae and  where X represents oxygen or -(CH 2 ) h -, d and d' each represent 0-2, d + d' is 2 or 3, f is 0 or 1 and h is 2 or 4, and (2) 5-30% of at least one hexaalkoxymethyl melamine, the alkoxy groups each having 1-4 carbon atoms; (D) 0.5-5 parts of a catalyst which is an organic tin derivative which may be selected from organotin salts of mono- or polycarboxylic acids or compounds of the formula where T is C 3 -C 20  alkyl, or a polymer possessing # Ti-O-Sn # chains which may be prepared by reacting alkyl titanates with organotin salts of mono- or poly-carboxylic acids; (E) 0.05-2 parts of an epoxysilane of the formula  or where R is C 1 -C 4  alkyl or phenyl, R' is C 1 -C 3  alkyl or methoxyethyl, R" is hydrogen or C 1 -C 3  alkyl and Q is C 1 -C 10  alkylene, a is 0 or 1, b is 0 or 2 and c is 0 or 1. Suitable solvents (F) are aliphatic ketones, alkyl esters of monocarboxylic acids, and halogenated or non-halogenated alkanes, cycloalkanes and aromatic hydrocarbons. Materials which may be coated include Kraft paper, glassine and sulphuric acid-treated papers, cardboards, vegetable parchment, papers coated with polyethylene or carboxymethyl-cellulose, sheets made of regenerated cellulose, or cellulose polyacetate, or polyethylene, polypropylene or polyethylene terephthalate, metal foils, woven fabrics based on synthetic fibres, glass fibres or asbestos fibres and non-woven fibrous materials based on cellulosic fibres and/or synthetic fibres. The compositions can be applied by conventional paper-coating machines such as gravure rollers, and dried and cured by heating In Example 1 a composition comprising (A) a gummy mixture of dimethylpolysiloxanes prepared by polymerising anhydrous octamethylcyclopolysiloxanes in the presence of KOH and then adding water, (C) methyltriacetoxysilane and hexamethoxymethylmelamine, (D) dibutyltin dilaurate, (E) an epoxysilane of the formula (F) methylethylketone, xylene and a petroleum fraction is coated onto either a refined bleached Kraft paper coated on one face with carboxymethyl cellulose or a non-refined bleached Kraft paper coated on one face with a polyethylene film. In Example 2 a composition comprising (A) the gummy mixture of dimethylpolysiloxanes as in Ex. 1, (C) a disiloxane of the formula and tetramethoxy diethoxymethylmelamine, (D) dioctyltin maleate, (E) an epoxysilane of the formula (F) methylethylketone and xylene, is coated on one face of a polyethylene film. In Example 3 a composition comprising (A) an α, #-dihydroxy-dimethylpolysiloxane oil (500 cP) and α, #-bis-(trimethylsiloxy)-dimethylpolysiloxane gum (30 x 10<SP>6</SP> cP), (B) a polysiloxane of the formula (C) tetramethoxy-dibutoxymethyl-melamine and a disilane (D) a catalyst of the formula (E) an epoxysilane of the formula and (F) ethyl acetate and xylene, is coated on a carboxymethyl-cellulose coated Kraft paper. The coatings in each case are cured by heating.