Patent GB-787175-A (GB)
Title: Curable organo-siloxane polymers with tin or zirconium catalyst
IPC: C08K5/00
Filed: 1954-03-05
Abstract: Chelates of tin used as curing catalysts for organosiloxane polymers (see Group IV (a)) may be made by reacting stannous hydroxide with aliphatic or aromatic acids containing at least one alcoholic hydroxyl group and at least one carboxyl group or the alkali or ammonium salts thereof.  Several hydroxy carboxylic acids are specified.  Zirconium chelates of the hydroxy carboxylic acids and of diketones are also specified.  In examples the preparations of (1) a stannous hydroxide ammonium tartrate chelate; (2) a stannous hydroxide sodium gluconate chelate; (3) a stannous hydroxide sodium citrate chelate; (4) zirconyl acetylacetonate; and (5) ammonium zirconyl glycollate, are described.ALSO:Organosiloxane polymers are cured by heating in the presence of a tin or zirconium chelate or an organic zirconium salt as curing catalyst in amount, for example, of 0.1 to 10 per cent by weight of the siloxane.  There are specified: tin chelates made, e.g. by reacting 1 mol. of stannous hydroxide with 1 to 2 mols. of an organic hydroxy acid (or the alkali metal or ammonium salt thereof), such as glycollic, lactic, b -hydroxy propionic, hydroxybutyric, glyceric, gluconic, mannonic, gluonic, glucoronic, tartronic, malic, tartaric, saccharic or citric acid; zirconium acetyl- and benzoyl-acetonates; chelates of zirconyl oxide with hydroxy organic acids or polyhydric alcohols, many examples of which are given; and zirconium salts of the formul  O=Zr(OR)2, [O=Zr(OR)]2O and Zr(OOCR1)4 where R is an acyloxy radical and R1 is an alkyl radical of 1 to 18 carbon atoms, examples of these also being given. Siloxane solutions or emulsions containing the catalysts and with or without thermosetting resins are stable for long periods of time, and find use for waterproofing textiles.  In examples: (1) a modified dimethylsilicone oil was emulsified with a fatty acid amide polyethylene oxide emulsifier, water, oleic acid and a stannous hydroxide ammonium tartrate chelate; (2) a similar emulsion was made except that the catalyst was a stannous hydroxide sodium gluconate chelate, and a separate portion of the emulsion was mixed with a water-soluble ureaformaldehyde condensate and an acid catalyst therefor; (3) a mono- and di-methyl and mono- and di-methyl hydrogen siloxane copolymer was emulsified with a quaternary ammonium salt, water and a sodium citrate stannous hydroxide chelate; (4), (5) solutions of a resin consisting of equal parts of an octamethylcyclotetrasiloxane and a linear dimethylsiloxane or of another siloxane resin were made containing zirconyl 2-ethylhexoate and other catalysts for comparative tests; (6) an emulsion of a siloxane resin was made with water, a cationic emulsifier and a xylene solution of zirconyl acetylacetonate; (7) a siloxane resin was emulsified with a quaternary ammonium salt, water and ammonium zirconyl glycollate; (8) a methylhydrogen siloxane oil was emulsified with water, a nonionic emulsifier, oleic acid and ammonium zirconyl glycollate and then mixed with a water-soluble melamine-formaldehyde resin and a curing catalyst therefor; (9) the silicone oil of (8) was emulsified with water, zirconyl 2-ethyl hexoate, toluene and a ureaformaldehyde resin.