Patent ID: 6110561
Filing Date: 2000-08-29
Classification: C08F,C08L,E04C,Y10T

Abstract:
A transparent multiribbed plate consisting essentially of an impact-resistant polymethyl methacrylate SP,wherein SP consists of:p1) 4-30 wt % of an elastomer phase E of crosslinked polymer particles, consisting of 60-99.9 parts by weight of an alkyl acrylate, an aryl acrylate or a mixture thereof, 0.1-10 parts by weight of one or more crosslinking agents containing at least two radially polymerizable ethylenically unsaturated groups, and 0-30 parts by weight of one or more monofunctional ethylenically unsaturated comonomers selected from the group consisting of vinyltoluene, styrene, and .alpha.-methylstyrene; andp2) 70-96 wt % of a polymethyl methacrylate P, containing from 0 to 20 parts by weight, relative to 100 parts by weight P, of units from one or more comonomers,wherein the elastomer phase E is a component of an emulsion polymer EP having at least a three-component particle construction, formed from a core K of polymethyl methacrylate P, a first shell S1 of the elastomer phase E, and a second shell S2 of polymethyl methacrylate P which forms part of a matrix phase M,wherein the elastomer phase E and the matrix phase M have refraction indices which are substantially the same, and the sum of p1) and p2) is 100 wt %,wherein the multiribbed plate has outer flanges (1a) and (1b) connected by ribs, optionally containing a middle flange positioned between the outer flanges and at a distance from each outer flange and wherein said middle flange is connected to each outer flange by said ribs,wherein the outer flange (1a) is on a side of the multiribbed plate exposed to weather during use and must have a thickness d, which satisfies the following relationship: ##EQU3## wherein d is the thickness of the outer flange (1a) in mm anda.sub.cU the Charpy impact resistance in kJm.sup.-2 of impact-resistant polymethyl methacrylate SP according to ISO 179/1fU, with the proviso that d is no more than 125% of its minimum value according to formula (I).