| 摘要 |
1361270 Retroreflective coatings MINNESOTA MINING & MFG CO 13 Oct 1971 [9 Nov 1970] 47741/71 Heading B2E [Also in Divisions B5 and G2] A retroreflective element (see Division G2) is prepared in Example 1 by embedding glass beads 1 into the polyethylene layer of polyethylene coated paper. The resultant web is vapour coated with aluminium 3, and the surface with the protruding beads knife coated with a layer of a solution containing an acrylic resin, a plasticiser and pigment, e.g. TiO 2 . After this layer is cured, the so-formed surface is laminated to a pressure-sensitive adhesive coated film, e.g. of polyester, and the polyethylene-coated paper stripped from the other surface. The exposed surfaces of the beads are then vacuum vapour coated to form an antireflective layer 5, e.g. using cryolite. In Example 2, a paper web is coated with styrene in xylol, the solution also containing benzoyl peroxide and di-t-butyl peroxide, cured, then coated with a composition containing polyvinyl butyral and carbon black, and finally coated with a composition comprising a polyester, a butylated melamine-formaldehyde resin in butarol and xylnol, the acetate of the monobutyl ether of diethylene glycol, carbon black and a coconut oil alkyd resin. Glass beads coated with silver are then coated onto the surface and allowed to partially embed. The paper web is then removed and a pressuresensitive adhesive carried on a polyethylene coated release paper laminated to the surface so exposed. The entire construction is then passed through a dilute solution of H 2 SO 4 and K 2 Cr 2 O 2 to remove the exposed silver on the beads, and the beads then vapour-deposited with cryolite. |
