Abstract: Flame-retardant fibrous material is prepared by reacting acrylonitrile polymer fibrous material with a guanidine compound of the formula ##STR1## where X and Y each represent hydrogen or an amine group, or a salt thereof, in a substantially water-free polar organic solvent in which the guanidine compound is soluble. The fiber produced incorporates both repeating diaminotriazine rings of the general formula ##STR2## dependent from the nitrile groups of the polymer chain and repeating groups of the general formula ##STR3## formed by cyclization of the polymer chain. The fibers can be rendered electrically conductive and used to form woven, non-woven or knitted fabrics.

Abstract: Cellulosic sheet material is processed in preparation for esterification for example acetylation to produce cellulose acetate, by treating the sheet material with water and then feeding the wetted material into a machine that simultaneously shreds and dries the material. The conditions in the machine are carefully controlled (outlet temperature not in excess of 110.degree. C. and moisture content 4-15% by weight) to ensure that the cellulosic material does not become deactivated towards esterification. The method enables low alpha content cellulosic material supplied in the form of high density sheet to be acetylated to produce high quality cellulose acetate flake.

Abstract: A marking comprises a layer, preferably of film-forming material, which contains a photochromic compound. The photochromic compound is capable of changing color when exposed to uv light, but can be converted to a permanently non-photochromic compound, preferably by overexposure to uv light. An image is formed in the layer by converting the photochromic compound to a permanently non-photochromic compound in one or more selected areas. When the layer is subsequently viewed under uv light a colorless image of non-photochromic compound can be seen on a background of colored photochromic compound.

Abstract: A fabric reinforcement for use with synthetic plastics material to produce a composite article is shaped to exhibit a tubular portion having a longitudinal axis, which can be curved, and at least one flange extending in the direction of the longitudinal axis. Using up to several interlinked tubular portions and a plurality of the flanges gives wide possibilities for the shape of the fabric reinforcing elements produced. Woven or knitted fabrics can be used.

Abstract: Filled polymer material, which is either textile material comprising filaments of a fibre-forming polymer filled with a particulate conductive material or sheet material of a polymer filled with a particulate conductive material, treated with an organic liquid to increase its electrical conductivity.

Abstract: A plurality of strands is introduced by a reciprocating weft laying device into a layer of paste-like bonding material deposited on the upper surface of an endless belt. A plurality of warp strands extending in the warp direction is introduced into the paste over the first mentioned strands. A second plurality of strands in the weft direction is similarly introduced by means of a second reciprocating weft laying device and a second plurality of strands in the warp direction is introduced over these second weft strands. The paste-like bonding material is then cured by a heated roller to produce the finished material. Material may be made having only one set of warp strands and one set of weft strands or more than two sets each of warp and weft strands.

Abstract: A plastics tile has a back ply having raised areas on one face which define at least one recess and a slug of facing material bonded in the or each recess. The slug or slugs are desirably either flush with or slightly proud of the raised areas of the back ply.

Abstract: A smoke suppressant for reducing smoke emission when a flammable organic material is heated above its decomposition temperature or ignited comprises a liquid heterocyclic polysulphide compound having the formulaR--S.sub.x --Z--S.sub.x' --R' (I)where R is an organic group containing 1 to 12 carbon atoms, R' is hydrogen or an organic group containing 1 to 12 carbon atoms, x is at least 2, x' is 1 or more when R' is hydrogen and is at least 2 when R' is an organic group and Z is a divalent radical derived from a heterocyclic compound, preferably a sulphur-containing heterocyclic compound such as thiadiazole. The compound (I) may contain dissolved or dispersed elemental sulphur. The smoke suppressant is particularly suitable for use in polyurethane foams.

Abstract: An S-aryl S-alkyl dithiocarbonate is prepared by pyroltically isomerizing an O-aryl S-alkyl dithiocarbonate at a temperature in the range 150.degree.-600.degree. C. The reaction product may be hydrolyzed to form an arenethiol or may be further reacted with an alcohol in the presence of a basic catalyst to form an aryl thioether.

Abstract: A polymer composition comprises a stable blend of two aqueous latices of particles having a polymeric core formed by emulsion polymerization of one or more olefinically unsaturated monomers and a polymeric shell formed on the core by emulsion polymerization of one or more olefinically unsaturated monomers in the presence of the core. The polymeric shell of the particles of the first latex contains functional groups capable of reacting with functional groups in the polymeric shell of the particles of the second latex to cause crosslinking between the particles of the two latices.

Abstract: Warp knitting of a stretch fabric suitable for outerwear end uses and simulating woven fabric is carried out to produce a coherent ground structure comprising non-elastomeric yarn, covered elastomeric yarns being laid into said ground structure.

Abstract: Cellulose fibres such as wood pulp are made more suitable for reinforcement of cement products by a treatment which reduces their swelling in aqueous and alkaline mediums. The fibres are dispersed in water, allowed to swell, and impregnated with a solution of a titanium and/or zirconium chelate compound. After drying, the fibres are heated to react the chelate compound(s) with the hydroxyl groups on the cellulose fibres, preferably to produce cross-linking between hydroxyl group residues.The treated fibres are more stable in cement media, and, despite their increased hydrophobicity, are dispersible in cement slurries to give good web formation in the manufacture of cement products such as sheet. They impart improved flexural strength and modulus to cement products compared with untreated cellulose reinforcing fibres.

Abstract: A mattress for supporting the human body, which is especially useful in hospitals or for home nursing of sick persons, comprises a body of open-cell foamed synthetic plastics material, with air passages extending up through a central region of the body. These air passages are open through the base of the central region of the mattress. The body of the mattress may comprise a base layer of foamed synthetic plastics material extending from head to foot of the mattress, and supporting elements in head and foot regions of the mattress located on this base layer. Each of these supporting elements may comprise foamed synthetic plastics material which is denser and less readily compressed than foam material in a central region of the mattress.

Abstract: Shaped articles, such as fibres and films, are obtained from a polymer solution comprising cellulose, a solvent for the cellulose comprising a cyclic tertiary amine N-oxide and water, and a stabilizer for the solution selected from the group consisting of sodium hexametaphosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, hydroxy-ethylidene diphosphonic acid, aminoethyl diphosphonic acid, and complexes of such compounds with occluded metal ions present in the polymer solution. The stabilizer is present in an amount sufficient to stabilize the solution against thermal degradation which causes loss of solvent and discoloration of solvent and dissolved cellulose.

Abstract: A yarn feed mechanism for a knitting machine incorporates a power operated yarn feed device, for example motor-driven rollers, a yarn take-up device, for example one or more pivotally mounted yarn take-up yarns, and a yarn restraining device, for example one or more yarn tensioning devices. The yarn feed mechanism is arranged so that yarn to be knitted follows a path from the yarn feed device through the yarn restraining device to the yarn take-up device and then to needles of the knitting machine.

Abstract: The wettability of polyolefin or polyester film for use as a heat exchange membrane, e.g. tubes or sheets, in a heat exchanger is increased, generally to a surface tension reading in excess of 70 dynes/cm, by treating the surface of the film with a strong oxidizing agent, particularly gaseous sulphur trioxide. The heat transfer coefficient is thereby improved. Tubes of such plastics material having a treated outer surface and an untreated inner surface are particularly useful for exchanging heat between a liquid flowing over the outer surface and a gas or vapor condensing within the tube.

Abstract: To facilitate control of a presser foot between knocking over bits in a flat V-bed knitting machine, at least some of the knocking over bits have inner edges whose lower portions have a smooth profile and are inwardly inclined, in the downward direction, with respect to the knocking over bits of the opposite needle bed.

Abstract: A resilient support for the human body, for example a mattress, comprises a resilient supporting block, for example of foamed polyurethane, and a fire resistant cover closely enclosing the block. At least part of the cover, which is use of the support, is intended to lie between the resilient block and a human body, is of stretch material and is able to conform to the adjacent surface of the resilient block when the support is subjected to deformation by a human body.

Abstract: A flat knitting machine including a presser foot assembly comprising a support mounted on the machine for movement along the needle array of the machine and at least one presser foot mounted on the support. The assembly includes a supporting arm carried on the support and itself carrying a slider on which a presser foot is mounted, the supporting arm providing a structure for effecting guided displacement of the slider up-and-down in relation to the needles. Resilient means, such as one or more springs, are arranged to urge the slider and presser foot down, away from the support, so that the presser foot can ride up on the supporting arm against the pressure of the resilient means and thus the whole of the presser foot extending from in advance of the rising needles to the rear of the fully raised needle position is resiliently mounted in the machine.

Abstract: A presser foot device for a knitting machine includes a blade-like support which, when mounted in the knitting machine, extends downwardly with respect to the needles of the machine, a presser element carried by the support near its lower edge, and a channel-like protective element which enfolds the lower edges of the blade-like support to protect it. The channel-like protective element may include two laminas one at each side of the blade-like support and extending at least as low as the lower edge of the blade-like support, and at least one connecting member joining the laminas and extending between them below the lower edge of the blade-like support.