CROSS-LINKED POLYCARBONATE RESIN WITH IMPROVED CHEMICAL AND FLAME RESISTANCE

摘要

Processes for increasing the chemical resistance of a surface of a formed article are disclosed. The formed article is produced from a polymeric composition comprising a photoactive additive containing photoactive groups derived from a monofunctional benzophenone. The surface of the formed article is then exposed to ultraviolet light to cause crosslinking of the photoactive additive and produce a crosslinked surface. The crosslinking enhances the chemical resistance of the surface. Various means for controlling the depth of the crosslinking are also discussed.

主权项

1. A method for preparing an article that has a high probability of passing a UL94 V1 test, comprising:
(a) designing a polymeric composition to be exposed to a designed dosage (D) of UV radiation, wherein the polymeric composition comprises:
(i) a cross-linkable polycarbonate resin having endcaps derived from 4-monohydroxybenzophenone and a weight average molecular weight of 15,000 to 30,000, and(ii) optionally one or more polymeric base resins, andwherein the polymeric composition has a designed weight percentage of the endcaps derived from 4-monohydroxybenzophenone (HBP), a designed melt flow rate (MF) and a designed weight average molecular weight (MW); (b) preparing the cross-linkable polycarbonate resin by interfacial polymerization; (c) optionally blending the cross-linkable polycarbonate resin with the optional one or more polymeric base resins to form the polymeric composition; (d) forming an article from the polymeric composition; and (e) exposing the formed article to the designed UV dosage;
wherein D, HBP, MF, and MW are selected based on an flame performance equation as follows:
Sqrt(p(FTP)+0.01)=−0.37308+(0.05345×D)+(0.22797×HBP)−(2.06081×10−6×MW)−(0.092440×MF)+(2.81460×10−6×MW×MF)−(0.000583×D2)wherein p(FTP) is the probability of a first time pass in a UL94 V1 test at 1.2 mm thickness after UV exposure and after 7 days of aging at 70° C.; p(FTP) is 0.7 or greater; D is at least 12 J/cm2 of UVA radiation; and MF is from 7 to 20 g/10 min measured at 300° C./1.2 kg/360 sec dwell.