Patent GB-1150491-A (GB)
Title: Process for Producing Decorative Surface Covering
IPC: C08J9/06
Filed: 1966-06-15
Abstract: 1,150,491. Ornamenting. CONGOLEUMNAIRN Inc. 15 June, 1966 [18 June, 1965], No. 26789/66. Heading B6G. [Also in Division B2] A process for producing a non-porous decorative surface covering having an inlaid decoration comprises depositing fine granules of resinous composition in a layer at least 0À015 inch in thickness on a backing 2, heating to cause sintering of said granules without complete coalescence thereof to form a layer of substantially uniform porosity, printing a design on the surface of the sintered layer with a sufficient amount of a resinous composition to permeate into the porous structure at the points of application and then consolidating the printed sintered layer into a non-porous sheet 48 by the application of heat. As described, the backing 2 is fed to a continuous conveyer 3 and an adhesive coating 4 is applied to it from a reservoir of coating composition 6 by a doctor blade 5; the coated backing is then conveyed to a distributing apparatus which covers the coated backing with a smooth layer of the fine granules, the distributing apparatus comprising a hopper 8 which holds a supply 9 of the granules and an inclined vibrating plate 10; the layer of granules 7 on the coated backing is then passed to an oven 12 in whch the layer is heated by a bank of infra-red lamps 13 to sinter the granules together. After cooling the granules are passed to a printing apparatus which deposits the resinous printing composition on the surface of the sintered granules 14. As shown, a series of printing blocks 18 with appropriate designs 19 etched in their surfaces with associated printing composition reservoirs 20 which supply printing composition to the face of the printing blocks by means of rolls 21, are used; the backing carrying the printed sintered granules is then passed through a heating unit 46 which includes infra-red lamps 47 and then to a pressing unit 48 which consolidates the granules to produce the uniform non-porous sheet 49. The pressing unit consists of a chrome surface roll 50 and a steel back-up roll 51 having a rubber cover 52. The pressing unit reduces the thickness by an amount from one-third to threequarters of its original thickness. A silk screen printing apparatus can be substituted for the block printing apparatus shown and the granules can be consolidated stepwise in a press instead of by using the rollers shown or the pressing step can be omitted. The granules are either transparent, translucent or opaque and when transparent or translucent granules are used, the adhesive coating is pigmented to provide a background colour. A substance which on further treatment will create voids in the granular layer can be mixed with the granules to increase the porosity and if desired produce an embossed effect. The substance can be one which is soluble in a solvent so that the substance can be removed subsequent to sintering by treating the sintered layer with the solvent; alternatively, it can be a substance which upon heating yields a gas; another substance which can be used is a plasticizer which is solid when mixed with the granules but which upon the heating of the granules to sintering temperature becomes absorbed by the resin of the granules. A still further substance is one which contracts upon heating, such as hollow spherical particles of resins such as styrene. When the printing composition is applied it penetrates into the sintered layer depending upon the amount and viscosity of the printing composition; when the heat (and pressure if used) is applied subsequent to the printing the voids will collapse, the areas with no printing composition being depressed to the greatest amount to produce the embossed effect. A small amount of a release additive can be mixed with the granules to aid removal from the surface of the pressing unit. The printing composition can incorporate a blowing agent which upon the application of heat in the subsequent heating and pressing operation decomposes so that the printed coat has a cellular composition to give a textured appearance. In one example the backing is a cellulosic felt sheet of approximately 0À043 inch thickness impregnated with 9% polyvinyl acetate and 30% of synthetic resin having a softening point of 125‹ F.; this is coated on one surface with the adhesive coating which consists of an emulsion which contains vinyl chloride polymer latex, butadiene acrylonitrile copolymer dispersion, titanium dioxide dispersion, calcium carbonate dispersion, sodium alkyl aryl sulfonate, methyl cellulose suspension and water, the coating emulsion being applied by means of the reverse roll coater and having a thickness of 0À003 inch, the coating being dried at a temperature of 300‹ F. for five minutes. The granules consisted of vinyl chloride homopolymer, dioctyl phthalate and a stabilizer mixed together at a temperature of 200‹ F. The granules were distributed on the coated backing to form a uniform layer of 0À08 inch thickness which was then heated for three minutes in an oven to 350‹ F. to sinter them together. After cooling a multi-colour design was printed on the surface utilizing a block printing machine and a printing composition consisting of vinyl chloride copolymer, dioctyl phthalate, titanium dioxide and naphtha. After printing consolidation was carried out at a pressure of 500 lbs. per sq. inch at a temperature of 350‹ F. for two minutes, the resulting sheet having a wear layer thickness of 0À032 inch and the printed design extending completely through the product. In a further example, the surface covering was produced as in the example above except that 20% by weight of sodium chloride was admixed with the granules and the layer of granules applied to the base was 0À05 inch in thickness, after sintering the sheet was washed in water to remove the sodium chloride and dried prior to printing; in place of the pressing step the printed sheet was heated to 375‹ F. and planished by passing between two rolls, the face roll being heated to approximately 250‹ F. and the back-up roll being rubber covered and unheated. Areas in the finished product which were not covered by the printing composition were depressed 0À01 inch below the surface of the product. Numerous materials are described as being suitable for the backing, granules, printing composition &c.