| 摘要 |
<p>1,249,127. Reflex-reflecting coatings. MINNESOTA MINING & MFG. CO. 24 Oct., 1968 [25 Oct., 1967], No. 50605/68. Heading B2E. [Also in Division C3] Reflex-reflecting coatings are obtained by appication of a coatable paint-like composition which comprising particles of a waterinsoluble thermoplastic organic resin having repetitive groups emulsified and dispersed in a continuous phase of water, a curing agent which can react chemically with the repetitive groups of the resin, the weight ratio of the curing agent to the thermoplastic resin being between 0.1 and 0.7, a water-miscible volatile organic liquid in which the curing agent is soluble, the organic liquid being present in an amount by weight no greater than twice the amount of water, and transparent glass microspheres having a refractive index of from 1.7 to 2.8 and a size of between 10 and 100 microns, which have been hemispherically metallised such that they have a specular reflecting hemispherical surface of metal adjacent to the glass of the microspheres and a hemispherical protective barrier film over the hemispherical metallic surface so as to prevent contact between the metal of the specular reflecting hemispherical surface and the other ingredients in the composition, the barrier film being substantially unreactive towards and resistant to removal by the other ingredients, the particle volume concentration in the composition being between 40 and 85%, the composition being spbstantially free of pigment particles smaller than 2 microns and the curing agent being in a phase apart from the dispersed resin particles. Coloured pigment, preferably spheroidal and having a size between 2-70 microns, and also a defoaming agent may optionally be included. The resin component is preferably a vinyl or acrylic resin containing repetitive carboxyl, hydroxyl, amine or amide groups; exemplified are acrylonitrile-acrylic acid-ethyl acrylate terpolymer, ethyl acrylate-methyl acrylate copolymer (which contains a small amount of carboxyl groups) and a vinyl acetate-vinyl chloride copolymer (which contains a small amount of OH groups). Suitable curing agents include condensates of formaldehyde with melamine or urea, and dimethylol ethylene urea. The organic liquid may be propylene glycol or glycerine. The glass microspheres may be metallised with, e.g. aluminium and the aluminised coating treated with aqueous ammonium dihydrogen phosphate or sodium dichromate to form a barrier coat thereon. For storage, the curing agent, unless only reactive at elevated temperatures, is preferably stored in a separate container from the resin. The composition can be applied by screen printing or spraying to a fabric or other surface in any desired pattern. It is particularly useful in marking or labelling sporstwear and other garments.</p> |
