GB792334A - Masonry block having integral molded facing layer and method of providing the same - Google Patents

Abstract

<PICT:0792334/III/1> <PICT:0792334/III/2> A masonry block is provided with an integral facing layer by placing in a mould 10, Fig. 1, a heat-curable composition 11 which cures without the formation of volatile by-products and comprises an ethylenically unsaturated alkyd resin, a polymerizable vinyl monomer and a granular mineral filler, the latter amounting to at least 50 per cent but not more than 90 per cent of the total weight of the resin, monomer and filler, introducing the block 12 into the mould with the surface to be provided with the facing downward, while the composition is in a semi-liquid condition and capable of permeating into the surface of the block, and curing the composition while the block is in contact with it in the mould. In the apparatus of Fig. 5, the moulds, which may be of glass, enamel- or porcelain-coated steel, or of stainless steel are passed by a conveyer chain 22 under a preheater 24, e.g. a bank of electric strip heaters or infra-red lamps, and are then charged with coating composition by an oscillating nozzle 28 connected with a mixing vessel 35, in which the composition may be subjected to vacuum while being mixed, and to air pressure while being discharged. The charged moulds are next passed over a shaker device 31 to level the composition and remove air bubbles, after which they are charged with the blocks to be coated, preferably preheated to the curing temperature, and pass to the curing chamber 41, which is heated, as by a perforated steam pipe 42; hot air curing may also be used. The preferred resins are the polymeric ester reaction products of one or more dicarboxylic acids, e.g. phthalic, malic, maleic, fumaric, adipic, pimelic, suberic, sebacic, itaconic, citraconic and succinic acids or their anhydrides, with polyhydric alcohols, e.g. ethylene glycol, diethylene glycol, or propylene glycol or mixtures thereof; some of the dicarboxylic acid component must contain an ethylenic linkage. Some of the polyhydric alcohol may be replaced by an unsaturated monohydric alcohol, e.g. allyl alcohol, and the resin may be modified or plasticised as by the addition of alcohols or fatty acids. Mixtures of rigid and flexible resins are preferred. The polymerizable vinyl monomer may be, e.g., styrene, vinyl toluene, cyclo-pentadiene, vinyl acetate, diallyl esters, e.g. diallyl phthalate, triallyl cyanurate, or alpha-methyl styrene. A preferred curing catalyst is methyl ethyl ketone peroxide, either alone or mixed with other catalysts such as benzoyl peroxide, dicumyl peroxide or cumene hydroperoxide. Metallic driers, e.g. cobalt, manganese and iron naphthenates, may also be added. The filler may be, e.g., calcium carbonate, clays, burnt clays, glass beads, asbestine, diatomaceous earth, silica flour, granular marble or sand, the last-named being preferred, and may be pre-coated or preresinated, e.g. by treatment with a siliconecontaining solution. Fillers of graded particle sizes are preferably used and a small proportion of a cation-modified clay as disclosed in U.S.A. Specification 2,531,427 is desirably incorporated. Fireproofing ingredients such as antimony trioxide, chlorinated paraffin or tricresyl phosphate may be included.ALSO:A masonry block is provided with a facing layer of a heat-cured composition comprising an ethylenically unsaturated alkyd resin, a polymerizable vinyl monomer and a granular mineral filler amounting to between 50 and 90 per cent of the total weight of the resin, monomer and filler. The preferred resins are the polymeric ester reaction products of one or more dicarboxylic acids, e.g. phthalic, malic, maleic, fumaric, adipic, pimelic, suberic, sebacic, itaconic, citraconic and succinic acids or their anhydrides, with polyhydric alcohols, e.g. ethylene glycol, diethylene glycol, or propylene glycol or mixtures thereof; some of the dicarboxylic acid component must contain an ethylenic linkage. Some of the polyhydric alcohol may be replaced by an unsaturated monohydric alcohol, e.g. allyl alcohol and the resin may be modified or plasticized as by the addition of alcohols or fatty acids. Mixtures of rigid and flexible resins are preferred. The polymerizable vinyl monomer may be e.g. styrene, vinyl toluene, cyclopentadiene, vinyl acetate, diallyl esters, e.g. diallyl phthalate; triallyl cyanurate; and alpha methyl styrene. A preferred curing catalyst is methyl ethyl ketone peroxide, either alone or mixed with other catalysts such as benzoyl peroxide, dicumyl peroxide or cumene hydroperoxide. Metallic driers, e.g. cobalt, manganese and iron naphthenates, may also be added. The preferred filler is sand, but calcium carbonate, clays, burnt clays, glass beads, asbestine, diatomaceous earth, silica flour, or granular marble may be used. The filler may be pre-coated or pre-resinated, e.g. by treatment with a silicone-containing solution. Fillers or graded particle sizes are preferably used, and a small proportion of a cation-modified clay, as disclosed in U.S.A. Specification 2,531,427, is desirably incorporated. Fireproofing ingredients such as antimony trioxide, chlorinated paraffin, or tricresyl phosphate and inhibitors, e.g. hydroquinone, t-butyl catechol and quinone, may be included.