GB804497A - Improvements in bonded and molded products and preparation thereof - Google Patents

Abstract

804,497. Agglutinated fibrous materials; laminates; coated fabrics. ROHM & HAAS CO. Nov. 25, 1955 [Dec. 9, 1954], No. 33820/55. Class 140. Fibres or filaments are bonded together by a polyvalent metal salt of a copolymer of monoethylenically-unsaturated monomers comprising 0.5 to 7 mol. per cent of monomers containing carboxyl groups, the polymer being cross-linked exclusively through the polyvalent metal. The fibres may be loose or in the form of carded webs, cut yarns or woven fabric, and may be of glass, mineral wool, jute, sisal, cotton, hemp, wool, ramie, cellulose acetate, casein, vinyl resins, including perhaloethylene resins, acrylic resins, polyamides or polyesters. The binder may be applied in aqueous dispersion which may be prepared by emulsifying a mixture of monomers with a non-ionic dispersing agent in the presence of a peroxidic free radical catalyst and subsequently neutralizing the dispersion with compounds which produce polyvalent metal ions or the preformed copolymer may be dispersed in water and treated with such compounds. The acidic monomers may be acrylic, methacrylic, ethacrylic, and other substituted acrylic, e.g. α-chloro-acrylic, itaconic, citraconic, maleic or fumaric acids. The bulk of the monomers may be of monomers which by themselves yield a soft polymer such as primary or secondary alkyl acrylates, alkyl methacrylates, with alkyl groups of more than 5 carbon atoms and vinyl esters of saturated monocarboxylic acids of more than 2 carbon atoms or of monomers which by themselves yield a hard polymer such as alkyl methacrylates with up to 4 carbon atoms in the alkyl group, t.-amyl methacrylate, t-amyl or t-butyl acrylate, cyclohexyl or benzyl acrylate or methacrylate, acrylonitrile, methacrylonitrile, styrene, vinyl chloride, chlorostyrene, vinyl acetate or p-methylstyrene. Mixtures of these may also be used. The metal compounds may be oxides of barium, calcium, magnesium or strontium; hydroxides of aluminium, lead or zirconium ; basic or normal salts such as barium, calcium, cadmium, cerium, strontium, zirconium, lead, cobaltous cobaltic, chromous, chromic, cupric, zinc, magnesium, ferrous, manganous, mercuric, nickelous, nickelic normal or basic acetates ; tartrates, citrates and oxalates may also be used, e.g. stannous tartrate or titanium oxalate. Basic aluminium acetate, basic aluminium formate and basic zirconyl acetate are especially suitable. As non-ionic dispersing agents can be used alkylphenoxypolyethoxyethanols with alkyl groups of 7 to 18 carbon atoms and 6 to 60 oxyethylene units; polyethoxyethanol derivatives of methylene linked alkyl phenols ; sulphur containing agents made, for example, by reacting 6 to 60 mols. ethylene oxide with nonyl, dodecyl, t-decyl, t-dodecylmercaptans or with alkylthiophenols with 6 to 15 carbon atoms in the alkyl group ; ethylene oxide derivatives of long-chain carboxylic acids of 6 to 60 oxyethylene units per molecule ; ethylene oxide derivatives of Long-chain alcohols, polyhydroxy compounds esterified or etherified with a hydrophobic chain, e.g. sorbitan monostearate containing 6 to 60 oxyethylene units ; block copolymers of ethylene and propylene oxide. As peroxidic free radical catalysts, redox type systems such as alkali metal or ammonium persulphates and perborates, hydrogen peroxide, organic hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide and esters such as t-butyl perbenzoate together with reducing agents such as sodium metabisulphite, watersoluble thiosulphates and hydrosulphites and salts of metals of variable valency such as cobalt, iron, nickel and copper sulphates. Non- woven mats of fibres may be made by depositing the fibres from an air stream on screens which may be in, e.g., the shape of a hat cone or a rectangular tray or in the form of an endless travelling belt. The fibres may be formed by extrusion of a melt or solution and coagulated and disrupted by a high-pressure air jet or by electrostatic spinning means. The dispersions may be applied to the mat or to fibres falling with the air stream or subsequently. A web formed of fibres may be coated on one or both sides with the dispersion. The binding agents may be used in conjunction with other adhesives such as glue, urea-, or melamine formaldehyde resins or potentially adhesive fibres may be used. The articles of the invention are suitable as reinforcements in moulded products, e.g. of polyester, vinyl or acrylic resins,. heat or sound insulation pads, liquid or gaseous filters, permeable membranes in storage batteries or electrolytic condensers, or cushioning or padding materials. Several layers may be laminated or paper layers may be laminated to one or both sides of a layer of the material to give a good insulating material. In an example, glass yarn fabric is sprayed with a dispersion formed by the emulsion copolymerization of ethyl acrylate, methyl methacrylate and methacrylic acid in the presence of tert-octylphenoxypolyethoxyethanol with benzoyl peroxide as catalyst and with aluminium acetate added. Nine layers of this are assembled while still wet, transferred to a heating preforming mould and set. This assembly is then inserted in a mould, surrounded by polyester resin and heated. In another example ten carded webs of cotton fibres carried on a travelling screen are sprayed with a dispersion of a copolymer of ethylacrylate, methylmethacrylate and acrylic acid, containing calcium oxide. The sprayed mat is conveyed between heated embossing rollers having regularly -spaced knobs to bend the fibres locally A thin paper sheet may be present below the web and another sheet may be fed on top of it after spraying. U.S.A. Specifications 2,255,313 and 2,607,756 are referred to.