Patent GB-833651-A (GB)
Title: Improved reflective pigments and coating compositions
IPC: B05D5/06
Filed: 1956-04-24
Abstract: A pigment consists of free-flowing reflexreflecting microspheroidal particles of glass that are given a hemi-spherical reflective coating of metal.  The reflective coating may be applied by forming a layer of the particles (which may be of 10 to 50 microns in diameter) on an easily softenable or soluble base, such as a web coated with plasticized resin or water-soluble dextrin adhesive and glue, then coating the exposed portion of the particles with metal, e.g. aluminium, copper, silver or tin by vacuum deposition or by chemical plating from solutions, or with nickel or chromium by exposure to gaseous carbonyls which are reduced in situ.  Transparent material such as cryolite may be applied to the particles by vacuum deposition before they are rendered reflective in order to modify their shape, e.g. to lengthen the optical axis.  The pigment can be incorporated in any kind of clear or coloured varnish such as oil or spirit resin varnishes or nitrocellulose or similar lacquers.  Examples are given of compositions containing (1) nitrocellulose; (2) neoprene rubber, phenolic varnish resin, and coumaroneindene resin; (3) nitrocellulose and alkyd resin; (4) nitrocellulose and screen process clear resin; and (5) nitrocellulose, alkyd resin plasticizer and melamine-formaldehyde hardener.  These compositions are suitable for painting road signs, trees, posts and the like to improve visibility in the light from motor-car headlamps; for coating garments, e.g. coats, jackets and shirts; and for advertizing signs.  If a smooth finish is desired, e.g. on motor car bodies, a top coat of clear or coloured varnish can be given.  Transparent, unreflectorized glass particles may also be included in these compositions, which may be applied by painting, spraying, printing or screenprocessing. Alternatively, the particles may be sprinkled on a paint or varnish surface while it is still tacky.  The particles forming the coating are randomly oriented.ALSO:A pigment consists of free-flowing microspheroidal particles of glass that are given a hemispherical coating of metal.  The reflective coating may be applied by forming a layer of the particles (which may be of 10 to 50 microns in diameter) on an easily softenable or soluble base, such as a web coated with plasticized resin or water-soluble dextrin adhesive and glue, then coating the exposed portion of the particles with metal, e.g. aluminium, copper, silver or tin by vacuum deposition or by chemical plating from solutions, or with nickel or chromium by exposure to gaseous carbonyls which are reduced in situ. Transparent material such as cryolite may be applied to the particles by vacuum deposition before they are rendered reflective in order to modify their shape, e.g. to lengthen the optical axis. The pigment can be incorporated in any kind of clear or coloured varnish such as oil or spirit resin varnishes or nitrocellulose or similar lacquers.  These compositions are suitable for painting road signs, trees, posts and the like to improve visibility in the light from motor-car headlamps; for coating garments, e.g. coats, jackets and shirts; and for advertising signs. Transparent, non-reflective, glass particles which are of similar size may also be included in the compositions.  Examples are given of compositions which contain, besides such conventional solvents as ethyl and butyl alcohols, the monoethyl and monobutyl ethers of ethyleneglycol, ethyl and butyl acetates, naphtha, xylol, toluol and cyclohexanone: (1) nitrocellulose; (2) a polychloroprene rubber mix including sodium acetate, MgO, ZnO and an antioxidant, a heat-hardening phenolic resin and a coumaroneindene resin; (3) Nitrocellulose and a short to medium oil length soya-modified phthalic alkyd resin; (4) Nitrocellulose and a screen process clear resin; and (5) Nitrocellulose, a non-drying alkyd resin plasticizer and a melamine-formaldehyde hardener.ALSO:A pigment consists of free-flowing reflex-reflecting microspheroidal particles of glass that are given a hemispherical reflective coating of metal.  The reflective coating may be applied by forming a layer of the particles (which may be of 10 to 50 microns in diameter) on an easily softenable or soluble base, such as a web coated with plasticized resin or water-soluble dextrin adhesive and glue, then coating the exposed portion of the particles with metal e.g. aluminium, copper, silver or tin by vacuum deposition or by chemical plating from solutions, or with nickel or chromium by exposure to gaseous carbonyls which are reduced in situ.  Transparent material such as cryolite may be applied to the particles by vacuum-deposition before they are rendered reflective in order to modify their shape, e.g. to lengthen the optical axis.  The pigment can be incorporated in any kind of clear or coloured varnish such as oil or spirit resin varnishes or nitrocellulose or similar lacquers.  Alternatively, the particles may be sprinkled on a paint or varnish surface while it is still tacky.