Patent GB-970494-A (GB)
Title: Werner complexes of chromium and the preparation thereof
IPC: C08J5/08
Filed: 1961-01-04
Abstract: Silica is coated with a complex of trivalent chromium with a mono-carboxylic acid which complex also contains anions of a strong monobasic inorganic acid such that the ratio of monobasic acid anions to chromium atoms in the complex is from 0.1: 1 to 1.2: 1 (see Division C2).  In Example (5) finely powdered silica is added to a solution of a complex of chromium with digallic acid and containing nitrate anions, the ratio of acid anion to chromium being 1: 1; a 1% solution of ammonia in water is added and the silica, coated with the chromium complex, is filtered off, washed, dried and screened.  The coated silica is used to fill an epoxy potting resin (see Division C3). Specifications 761,834, 776,156, and 785,784 are referred to.ALSO:The invention comprises an aqueous solution of a chromium complex in which the ratio of monobasic inorganic acid anions to chromium atoms is from 0.1:1 to 1.2:1 and which are prepared by reacting together a water-soluble chromium compound, a monobasic inorganic acid having a dissociation constant greater than 1X10-5, an alcohol that is water-soluble to the extent of at least 5% by weight at 20 DEG C., and a monocarboxylic acid. Hexavalent chromium compounds, especially chromium trioxide, are preferred.  Specified alcohols are methanol, ethanol, n- and iso-propanol, butanol, 2-butanol and cyclohexanol.  Specified monocarboxylic acids include numerous saturated or unsaturated, straight- or branched-chain aliphatic, aromatic or heterocyclic acids which may be unsubstituted or substituted with fluorine or chlorine atoms or nitro, amino, hydroxyl, cyano or esterified carbonyl groups, the preferred acids being methacrylic, acrylic, gallic, digallic, aminobenzoic, cyanoacetic, b -resorcylic, trifluoroacetic and gluconic acids, and lysine.  Hexavalent chromium compounds are reduced to the trivalent state in the presence of the complexing carboxylic acid.  In examples (1) and (2) chromium trioxide is dissolved in a mixture of water and concentrated hydrochloric acid, the resultant solution being added to a solution of methacrylic acid in iso-propanol and the mixture is refluxed. In further examples the acids used are: (4) methacrylic and nitric; (5) digallic and nitric; and (6) caproic and hydrochloric. The complexes are used in the sizing of glass fibres (see Division D1) and glass fabrics (see Division B2) which are converted into fibrous aggregates (see Division D1) or laminates (see Division B5), and for coating silica (see Division C1) which is used for filling epoxy resins (see Division C3). Specifications 761,834, 776,156 and 785,784 are referred to.ALSO:An epoxy potting resin is filled with coated silica (see Division C1), the coating consisting of a complex of trivalent chromium with a monocarboxylic acid, which complex also contains anions of a strong monobasic inorganic acid such that the ratio of monobasic acid anions to chromium atoms in the complex is from 0.1:1 to 1.2:1 (see Division C2).  In Example (5) metaphenylene diamine is added to an epoxy resin having an epoxide equivalent of 175 and an average molecular weight of 350 and then silica coated with a complex of chromium with digallic acid and containing nitrate ions is added; the composition is moulded into discs.  A size solution for treatment of glass fibres comprises an aqueous plasticized polyvinyl acetate emulsion, an antifoam agent, a size lubricant, ammonium hydroxide and a complex of chromium with methacrylic acid, the complex also containing chloride ions. Specifications 761,834, 776,156 and 785,784 are referred to.ALSO:Glass fabric is coated with a complex of trivalent chromium with a mono-carboxylic acid, which complex also contains anions of a strong monobasic inorganic acid such that the ratio of monobasic acid anions to chromium atoms in the complex is from 0,1 : 1 to 1,2 : 1 (see Division C2).  In Example (1) glass fabric is immersed in a solution of a complex of chromium with methacrylic acid and containing chloride ions, passed through a wringer and heat-dried. Specifications 761,834, 776,156 and 785,784 are referred to.ALSO:Glass fibres are sized with a complex of trivalent chromium with a mono-carbonylic acid, which complex also contains anions of a strong monobasic inorganic acid such that the ratio of monobasic acid anions to chromium atoms in the complex is from 0.1:1 to 1.2:1 (see Division C2).  In Example (3) a solution of a complex of chromium with methacrylic acid and containing chioride ions is added to a mixture of a dispersion of a size lubricant in water and a plasticised polyvinyl acetate emulsion containing an antifoam agent. Dilute ammonium hydroxide solution is added and the solution is used to size cooled borosilicate fibres by passing the solution and glass fibres over a circular graphite wheel.  The fibres are gathered into a bundle, wound on to a spool and then dried to harden the size.  The dried sized glass may be formed into a fibrous aggregate by cutting lengths of the glass strands and folding them into a bundle which is soaked with a low pressure polyester resin (70% polyester and 30% styrene) containing 1% benzoyl peroxide as curing catalyst.  The bundle of glass fibres is then placed in a die and placed in an oven until the resin has cured.  Specifications 761,834, 776,156 and 785,784 are referred to.