GB802329A - Novel buoyant bodies of polyurethane foam and a process for making the same - Google Patents

Abstract

The invention comprises a buoyant body of polyurethane foam having an outer layer comprising a fleece, the core of the float being of a density which is low in comparison with the density of the outer layer. The "fleece" is a three-dimensional fleece of mechanically bound glass fibres, polyurethane fibres, polyamide fibres, acetylcellulose fibres, leather fibres, horsehair or other technical fibres, metal fabrics and metal threads. Combinations of such fleeces may be used. Bodies having a core of a density of 10 to 100 kg./m.3 and an outer layer of a density of 200 to 800 kg./m.3 can be produced. The outer layer may be of a thickness of 2 to 30 mm. depending on the thickness of the fleece used. Advantageously, the process described in Specification 769,680 is used for the preparation of the foam, in conjunction with the apparatus described in Specification 769,682, [Group III]. The fleece may be pretreated with activators such as tertiary amines, to act as catalysts and increase the homogeneity and density of the outer layer. The buoyant bodies can be provided with fastening devices, which may be mounted in the mould prior to the foaming process or they may be attached to parts of the outer layer which are reinforced with additional fleeces and supported by pegs and plugs of heavy foamed plastic, wood or metal, which are mounted in the mould before foaming is effected. To form a more impermeable outer layer, the mould, before the fleece is applied, may be provided with a layer of synthetic resin or reactants producing it, such as mixtures of hydroxyl and carboxy polyesters with isocyanate modified polyesters, maleic acid/phthalic acid/glycol polyesters, styrene and its mixtures with polyisocyanates, curable rubber latex, polyethylene dispersions or lacquers. In addition to the fleece there may be applied to the mould a fabric impregnated with a stabilized polymerizable polyesterperoxide mixture, polymerization of which is brought about during the reaction producing the foam. Alternatively, a buoyant body produced by the process may have applied such an impregnated glass fabric which is then heated to produce an impermeable cover. In a further method a core of the buoyant body is wrapped in glass fabric which is then impregnated with polyesters or polyurethane composition, the wrapped core is placed in a mould, and the polyurethane composition is sucked up into the mould. Hollow buoyant bodies are obtained by casting a foamable mixture around a thin-walled hollow body of metal or plastic or from half or part shells which are then joined by adhesives. In examples: (1) a mould is sprayed with a solution of a mixture of maleic acid/glycol polyester, styrene, titanium dioxide, benzoyl peroxide and dimethyl aniline which is then reacted by heating with infra-red rays. A second application of the solution is made and then a felted cotton fleece is pressed on to the fresh coating. There is then introduced a mixture, yielding a foamed product, comprising an adipic acid/trimethylol propane/phthalic acid hydroxy-polyester, siliceous chalk, diethylamino-ethanol adipic acid ester and toluylene diisocyanate, the heat and pressure generated in the foam formation also hardening the polyester composition; (2) to a greased mould is applied a mixture of adipic acid/phthalic acid/trimethylol propane/butenediol hydroxy-polyester, adipic acid/diethylene glycol/trimethylol propane hydroxy-polyester, cyclopentenone carboxylic acid methyl ester iron complex and toluylene diisocyanate and a glass fibre fleece is then put in position. Into the mould there is then introduced a foamable mixture of adipic acid/trimethylol propane/phthalic acid hydroxy-polyester, adipic acid 1 : 3-butylene glycol/trimethylol propane hydroxy polyester, siliceous chalk, an activator mixture of diethylene glycol adipic acid ester, aqueous sulphonated castor oil and diethylamine oleate, and toluylene diisocyanate; (3) two half-shells prepared from mixtures described in Example (2) are bonded together using a polyurethane adhesive from adipic acid/hexanetriol/butanediol polyester, ethyl acetate and toluylene diisocyanate; (4) into a mould lined with glass fibre fleece is introduced a foamable mixture of adipic acid/phthalic anhydride/trimethylol propane/1 : 3-butanediol polyester, adipic acid/diethylene glycol/trimethylol propane polyester, titanium acid-tertiary butylate, bis-(diethylaminoethyl) adipate, aqueous sulphonated castor oil and toluylene diisocyanate; (5) a moulded polyurethane foam core prepared from a foamable mixture of the same ingredients as in Example (4) is wrapped in a glass fibre fleece, placed in a mould and impregnated by sucking up by means of a vacuum a mixture of adipic acid/phthalic anhydride/trimethylol propane/1,3-butanediol polyester, adipic acid/diethylene glycol/trimethylol propane polyester, a ferric complex salt of cyclopentenone carboxylic acid and toluylene diisocyanate. In the examples, a mixture of 1,2,4- and 1,2,6-toluylene diisocyanates is used. In its place there may be used 1,4-phenylene diisocyanate, 1-5-naphthylene diisocyanate, triphenylmethane - 4,41,411 - triisocyanate, diphenylmethane-4,41-diisocyanate and dimethyl diphenyl-4,41-diisocyanate.ALSO:A buoyant body of polyurethane foam having an outer layer comprising a fleece of mechanically bound fibres of glass, polyurethane, polyamide, acetylcellulose, leather, horsehair or metal is moulded by lining a two part mould with the fleece, introducing a foamable mixture comprising a polyester containing hydroxyl and/or carboxyl groups and a polyisocyanate into one mould half and then closing the mould halves. Fastening devices and reinforcing members of foamed plastic, wood or metal may also be put in the mould before the foaming is carried out. To form a more impermeable layer, the mould, before the fleece is applied, is provided with a layer of synthetic resin or reactants for producing it, such as mixtures of hydroxyl and carboxyl polyesters with isocyanate modified polyesters; maleic acid/phthalic acid/glycol polyesters; styrene and its mixtures with polyisocyanates; curable rubber latex; polyethylene dispersions; or lacquers. In addition to the fleece there may be applied to the mould a fabric impregnated with a stabilized polymerisable polyester/peroxide mixture, polymerisation of which is brought about during the reaction which produces the foam. Alternatively, to a buoyant body produced according to the above process there may be applied an impregnated glass fabric which is then heated to produce an impermeable cover. In a further method a core of the buoyant body is wrapped in glass fabric which is then impregnated with polyesters or a polyurethane composition, the wrapped body is place in a mould and the foamable polyurethane is sucked up into the mould. Hollow buoyant bodies can be produced by casting the foamable mixture around a thin-walled hollow body of metal or plastic, or from half or part shells which are then joined by polyurethane adhesives. Examples employing specific polyurethane are given (see Group IV(a)). Specifications 769,680 [Group IV(a)] and 769,682 [Group III] are referred to.ALSO:The invention comprises a buoyant body of polyurethane foam, such as may be used in deep-water fishing, and the interior of which is of low density in comparison with the density of the outer layer, having an outer layer comprising a fleece of mechanically bound fibres of glass, polyurethane, polyamide, acetylcellulose, leather, horsehair or metal, which may be made by lining the mould with the fleece and introducing a foamable mixture comprising a polyester containing hydroxyl and/or carboxyl groups and a polyisocyanate into the mould. The fleece is penetrated by the mixture and hinders foaming to form an impermeable outer layer of higher density than the foam in the interior. Fastening devices and reinforcing members of foamed plastic, wood or metal may be put into the mould before the foaming is effected. To form a more impermeable layer the mould, before the fleece is applied, may be provided with a layer of synthetic resin. In addition to the fleece there may be applied to the mould a fabric impregnated with resin-forming reactants. In a further method the foamable mixture is cast around a thin-walled hollow body of metal or plastic, or half or port shells formed by the above methods are joined by polyurethane adhesives. Specifications 769,680, [Group IV (a)], and 769,682, [Group III], are referred to.