Patent GB-972442-A (GB)
Title: Reflex reflecting dry transfer films
Inventor: BERG HAROLD ARTHUR
IPC: D06H1/00
Filed: 1960-11-02
Abstract: 972,442. Laminates. MINNESOTA MINING & MANUFACTURING CO. Nov. 2, 1960 [Nov. 2, 1959], No. 37673/60. Drawings to Specification. Heading B5N. [Also in Division B6] A flexible reflex-reflecting transfer film material comprises a flimsy and stretchable transfer film structure and a dimensionally-stable drystrippable temporary carrier structure, which transfer film structure includes a layer of projecting transparent glass beads with underlying reflective means partially embedded and permanently bonded in a flexible and stretchable binder layer, and an adhesive coating on the rear face of said binder layer, the dry-strippable carrier structure having a low-adhesion plastic coating into which the beads are temporarily embedded. The dimensionally-stable carrier base is non-thermoplastic and may be calendered paper 0.006 inch thick. The plastic coating has a melting point from 150 to 350 F., and may be polyethylene, of molecular weight 18,000. The beads may be coloured, and have a refractive index 1.7-2.0. The reflecting means may be a coating on the rear halves of the beads of silver, aluminium or other metal, or the bead-binder layer may contain a reflective pigment such as titanium dioxide or pigment flakes of aluminium or copper of particle size 20-150 microns. The bead-binder is a rubberbased adhesive composition, e.g. rubbery butadiene acrylonitrile copolymer 9.5 parts; dioctylphthalate plasticizer 1.8 parts; ketonesoluble heat-reactive phenol-aldehyde resin 15.6 parts; ethylene glycol monoethyl ether organic solvent 5.6 parts; methyl isobutyl ketone organic solvent 56 parts. A heatbarrier coating is applied over the bead-binder, and may comprise: rubbery butadiene acrylonitrile copolymer 12 parts; ketone-soluble heatreactive phenol-aldehyde resin 12.2 parts; dioctylphthalate plasticizer 2.4 parts; methyl isobutyl ketone 73 parts. The adhesive coating may comprise 25 parts of a thermoplastic copolymer composed of 85% vinyl chloride and 15% vinyl acetate, 16.7 parts of dioctylphthalate plasticizer, and 0.5 parts of aluminium powder pigment; dissolved in a mixture of 38 parts methyl ethyl ketone and 19.8 parts toluene. A temporary protective liner is then applied, e.g. a 0.004 inch thick sheet of embossed polyethylene film. The material is cut into desired shapes and applied to an article, e.g. cloth by application of a hot household iron, or by activating the adhesive with organic solvents. In a method of manufacturing the transfer material, the carrier base is coated with polyethylene and passed round a hot cylinder at 170 F., while passing the tacky polyethylene through a trough of glass beads beneath the cylinder a layer of beads sticking to the coating. On heating the assembly to 270 F., the beads sink or are drawn into the polyethylene up to 50% their diameter. After cooling, the beadbinder is applied by knife-coating and dried by evaporating the solvent. The heat-barrier coating is applied in the same manner. The binder and carrier layers are cured by heating to 270 F. for 10-15 minutes. The adhesive is applied also by knife-coating and solventevaporation. Specification 556,935 is referred to.