GB811122A - Improvements in or relating to a method of coating building blocks - Google Patents

Abstract

<PICT:0811122/III/1> The face of a moulded masonry building block is coated by placing a temporary elastic band support member around the unit near the face to be coated, placing on the support a rigid frame capable, when in co-operation with the support, of preventing a semi-liquid coating composition from flowing down the sides of the block, pouring a flowable coating composition uniformly upon the face of the block and curing the composition until it is rigid and firmly fixed to the surface of the block. The elastic support member 11, as shown, may be a band of a material such as natural or synthetic rubber, and the building unit 10 may be a block made from cinders, slag, cement, "Haydite" (Registered Trade Mark), clay or the like. The rigid frame 12 may be made of materials such as stainless steel, glass or stiff paper or other rigid composition, and may be coated with glass enamel, frit or porcelain. Both it and the support member may be coated with a lubricant such as polymeric dimethyl siloxane oil. The coating composition 13 may comprise a polyester resin, or preferably a mixture of flexible and rigid polyester resins, a curing catalyst and pigments and fillers; a monomeric cross-linking solvent such as styrene, vinyl toluenes, cyclopentadiene, vinyl acetate, diallyl esters, triallyl cyanurate and alpha methyl styrene is preferably also included. The polyester resins may be the polymeric reaction products of one or more dicarboxylic acids, e.g. phthalic, malic, maleic, fumaric, adipic, pimelic, suberic, sebacic, itaconic, citraconic and succinic acids and their anhydrides, with polyhydric alcohols, e.g. ethylene glycol, diethylene glycol, propylene glycol, or a mixture of propylene glycol and dipropylene glycol. Part of the dicarboxylic acid component must be ethylenically unsaturated. The polyhydric alcohol may be partially replaced by an unsaturated monohydric alcohol, e.g. allyl alcohol. The resin may be modified or plasticized by the incorporation of alcohols or fatty acids. Polymerization inhibitors including hydroquinone, t-butyl catechol and quinone may be present. The preferred curing catalyst is methyl ethyl ketone peroxide but di-cumyl peroxide, cumene hydroperoxide and benzoyl peroxide may also be used; the use of a metallic drier, e.g. manganese, cobalt or iron naphthenate, in conjunction with these, is desirable. Fireproofing agents, e.g. antimony trioxide, chlorinated paraffins and tricresyl phosphate may also be included. The filler may include sand, calcium carbonate, clays, burnt clays, glass beads, asbestine, diatomaceous earth, silica flour, and other natural or manufactured granular particles; in an example, ceramic frit coated coloured rock granules are mentioned. Titanium dioxide is mentioned as a pigment. Fillers with a mixture of particle sizes are preferred, e.g. mixtures of graded sand. A small quantity of a cation-modified clay may be included.ALSO:A coating-composition for moulded masonry building-blocks comprises an unsaturated polyester resin, or preferably a mixture of flexible and rigid unsaturated polyester resins, a curing catalyst, one or more finely divided fillers and a monomeric cross-linking solvent such as styrene, o-, m- and p-vinyl toluenes, cyclopentadiene, vinyl acetate, diallyl esters (e.g. phthalate), triallyl cyanurate or alpha-methyl styrene. The unsaturated polyester resins may be the polymeric reaction products of one or more dicarboxylic acids, e.g. phthalic, malic, maleic, fumaric, adipic, pimelic, suberic, sebacic, itaconic, citraconic and succinic acids and their anhydrides, with polyhydric alcohols, e.g. ethylene glycol, diethylene glycol, propylene glycol or a mixture of propylene glycol and dipropylene glycol. Part of the dicarboxylic acid component must be ethylenically unsaturated. The polyhydric alcohol may be partially replaced by an unsaturated monohydric alcohol, e.g. allyl alcohol. The resin may be modified or plasticised by the incorporation of alcohols and fatty acids. Polymerization inhibitors including hydroquinone, t-butyl catechol, and quinone may be present. The preferred curing catalyst is methyl ethyl ketone peroxide, but di-cumyl peroxide, cumene hydro-peroxide, and benzoyl peroxide may also be used either alone or with methyl ethyl ketone peroxide; the use of a metallic drier, e.g. manganese, cobalt or iron naphthenate or mixtures thereof is also desirable. Fireproofing agents, e.g. antimony trioxide, chlorinated paraffins and tricresyl phosphate, may also be included. The filler may include sand, calcium carbonate, clays, burnt clays, glass beads, asbestine, diatomaceous earth, silica flour, and other natural or manufactured granular particles; in Example (6), ceramic frit coated coloured rock granules are mentioned. Titanium dioxide is mentioned as a pigment. Fillers with a mixture of particle sizes are preferred, e.g. mixtures of graded sand. A small quantity of a cation-modified clay may be included, e.g. dimethyldioctadecyl ammonium bentonite. Silicone oils, e.g. polydimethyl siloxane, may also be added.