Patent ID: 6501219
Filing Date: 2002-12-31
Classification: C03C,C09D

Abstract:
An environmentally favorable method for making a shatter resistant incandescent lamp having a substantially transparent tack-free silicone coating on the incandescent lamp bulb, comprising the steps of:(I) treating the surface of the bulb of the incandescent lamp with the substantially volatile organic solvent-free, platinum group metal catalyzed, heat curable silicone coating composition comprising by weight, (a) 100 parts of an alkenyl-terminated polydiorganosiloxane mixture consisting essentially of (i) a low molecular weight alkenyl-terminated polydiorganosiloxane having a viscosity of about 500 centipoise to about 15000 centipoise at 25Â° C. and (ii) a high molecular weight alkenyl-terminated polydiorganosiloxane having a viscosity of about 40,000 centipoise to about 220,000 centipoise at 25Â° C., where there can be present in the alkenyl-terminated polydiorganosiloxane mixture from about 0.02 to 0.5 part of (i), per part of (ii), (b) 5 to 50 parts of a silicone resin having a ratio of organo radicals to silicon which has a value of about 0.5 to 2, where the organo radicals are selected from the group consisting of C(1-6) organo radicals, C(2-6) alkenyl radicals, and a mixture thereof, and the silicone resin comprises â€œQâ€  units having the formula, SiO2, chemically combined with a member selected from the group consisting of â€œMâ€  units having the formula, (R)a(R1)bSiO0.5, and a mixture of â€œMâ€  units and â€œDâ€  units having the formula, (R2)2SiO, where R is a C(1-6) organo radical, R1 is a C(2-6) alkenyl radical, R2 is selected from R, R1, and a mixture thereof, â€œaâ€  is an integer having a value of 2 or 3, â€œbâ€  is a whole number having a value of 0 or 1, and the sum of a+b is equal to 3, (c) 0.1 to 10 parts of a silicon hydride cross-linking agent, and, (d) an effective amount of an inhibited platinum group metal catalyst; and (II) heating the. treated incandescent lamp at a temperature in the range about 100Â° C. to about 200Â° C. until the silicone treated incandescent lamp bulb surface is substantially tack-free.