Patent GB-923382-A (GB)
Title: Werner complexes and the preparation thereof
IPC: C03C25/38
Filed: 1961-04-13
Abstract: Compositions of epoxide resins, e.g. those obtained from reaction of epichlorohydrin and polyhydric phenols and alcohols and those obtained by epoxidation of fusible, hydroxy group containing phenol formaldehyde resins with haloepoxy alkanes, such as epichlorohydrin, incorporating a curing agent, e.g. primary aliphatic amines such as diethylene triamine, cyclic aliphatic amines such as piperidine, aromatic amines such as metaphenylene diamine, and organic acids and acid anhydrides such as oxalic acid and phthalic anhydride are used to impregnate resin-reinforcing or -filling materials, e.g. glass fibres, or cloth, inorganic fillers such as clay, silica, mica, alumina and asbestos or organic materials such as cellulose, paper or natural or synthetic fibres or fabric previously treated with a Werner chromium complex of a trihydroxybenzoic acid and/or an organic substance capable of yielding a trihydroxybenzoic acid on hydrolysis (see Group IV(b)). In an example, 14 parts of metaphenylene diamine are mixed with 100 parts of a liquid epoxide resin having an average molecular weight of 350 to 400.  In another example 100 parts of a mixture of 14 parts of metaphenylene diamine per 100 parts of epoxide resin having an average molecular weight of 350 is added 100 parts of a mixture, formed by adding 200 parts of silica, 700 parts of water and 2 parts of a chromium complex of gallic acid and by subsequently removing the water.  The resins may be phenolic or melamine resins. Specifications 518,057, 579,698 and U.S.A. Specifications 2,324,483, 2,444,333, 2,494,295, 2,500,600, 2,511,913, 2,544,667, 2,683,130, 2,683,156, 2,695,894, 2,763,573 and 2,829,124 are referred to.ALSO:The invention describes a Werner chromium complex of a trihydroxybenzoic acid and/or an organic substance capable of yielding trihydroxybenzoic acid on hydrolysis.  Specified complexes are those of gallic, tannic and pyrogallol carboxylic acids and other glucosides which give gallic acid on hydrolysis. The complex, in which preferably the proportion of atoms to moles of carboxylic acid is from 0.2:1 to 2.0:1, is obtained by heating the starting materials together under reflux preferably in the presence of isopropanol as solvent.  The complexes are used to treat fabrics (see Group IV(c)) prior to treating with epoxide resins to form laminates (see Group VIII).  In an example a chromium complex of tannic acid containing 5% chromium and having a chromium to carboxylic acid mole ratio of 1:1 is prepared by refluxing 613 grams of basic chromic chloride and 310 grams of tannic acid with water at 79 DEG C. for 15 minutes and cooling to room temperature.  In another example a chrome complex of gallic acid containing 3% chromium and having a chromium to carboxylic acid mole ratio of 1 to 1 is prepared by refluxing at 80 DEG C. for 15 minutes 591 grams of basic chromic chloride, 147 grams of gallic acid and 762 grams of isopropanol.  Specifications 518,057, 579,698, and U.S.A.  Specifications 2,324,483, 2,444,333, 2,494,295, 2,500,600, 2,511,913, 2,566,667, 2,683,130, 2,683,156, 2,695,896, 2,763,573 and 2,829,127 are referred to.ALSO:A resin-reinforcing or -filling material e.g. glass fibres or cloth, inorganic fillers such as clay, silica, mica, alumina and asbestos, or organic material such as cellulose, paper, or natural or synthetic fibres or fabric, is pretreated with a Werner chromium complex of a trihydroxybenzoic acid and/or an organic substance capable of yielding a trihydroxybenzoic acid on hydrolysis (see Group IV (b) ) prior to incorporating in a resin e.g. an epoxide resin, for example those obtained from the reaction of epichlorohydrin and polyhydric phenols and alcohols and those obtained by epoxidation of fusible, hydroxy group containing phenol formaldehyde resins with haloepoxy alkanes, such as epichlorohydrin, or in phenolic or melamine resin to form laminates (see Group VIII).  The complexes which may be prepared from tannic, gallic or pyrogallol carboxylic acids or glucosides giving gallic acid on hydrolysis are preferably used in dilute solutions, e.g. a 2% aqueous solution of a complex containing 3% chromium is prepared, neutralized to a pH of about 5,5 and the material, such as glass cloth, is immersed in the aqueous solution.  The wet cloth is then dried at an elevated temperature to set the complex.  Specifications 518,057, 579,698 and U.S.A. Specifications 2,324,683, 2,444,333, 2,494,295, 2,500,600, 2,511,913, 2,544,667, 2,683,130, 2,683,156, 2,685,894, 2,763,573 and 2,829,124 are referred to.