| 摘要 |
<p>#CMT# #/CMT# Thermoplastic compositions (I) comprising (a) a thermoplastic matrix and (b) copolymer(s) of 1-4C alkyl methacrylate, 1-8C alkyl acrylate and a styrene monomer, in which the 1-4C alkyl methacrylate makes up more than 75 wt.% of the total monomer content and the styrene monomer makes up 3-20 wt.%. #CMT# : #/CMT# Independent claims are also included for (1) a method for the production of articles by forming a thermoplastic composition (I) (2) formed articles made from (I) . #CMT#USE : #/CMT# For the production of formed articles such as compact or expanded profiles, compact or expanded slabs or tubes. #CMT#ADVANTAGE : #/CMT# The introduction of particular styrene momomers facilitates the incorporation of the acrylate monomer and greatly improves the homogeneity and isotropy of the copolymer and its compatibility with thermoplastic matrices. When used as a processing aid in a matrix polymer such as PVC, this results in products with a homogeneous appearance (even after extrusion) and isotropic mechanical properties such as strength, elongation at break and elasticity. #CMT#POLYMERS : #/CMT# Preferred Materials: The matrix (a) comprises polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene copolymer (ABS), acrylate-styrene-acrylonitrile copolymer (ASA), polycarbonate-polyester, polycarbonate-ABS or polycarbonate-ASA, especially PVC. Preferred alkyl acrylate monomers are ethyl, n-butyl and 2-ethylhexyl acrylate, especially n-butyl acrylate, present in amounts of 5-25 wt.% based on total monomers. Preferred stryene monomers are styrene, ethylstyrene and alpha -methylstyrene (4-12 wt.% of total monomers). The composition (I) contains 0.3-20 wt.% copolymer (b), preferably a copolymer of methyl methacrylate, n-butyl acrylate and styrene. Preferred Articles: Compact or expanded profiles, compact or expanded slabs, or tubes. #CMT#EXAMPLE : #/CMT# A mixture of 8500 g water, 5.23 g sodium carbonate and 78.2 g sodium lauryl sulfate was treated with a mixture of 4427.9 g methyl methacrylate, 260.5 g styrene, 520.9 g n-butyl acrylate and 0.18 g n-octyl mercaptan; when the temperature reached 55[deg] C, the mixture was treated with 7.81 g potassium persulfate in 148.39 g water followed by 50 g water to wash out the line, polymerised for 60 minutes after the peak exotherm and then cooled to 30[deg] C to form a latex. This contained a copolymer (Ex3) with a peak width at half-height of 1.1 as determined by liquid adsorption chromatography, compared with 2.2 for a copolymer of 4688 g methyl methacrylate and 521 g n-butyl acrylate (C3); the homogeneity of the copolymer was therefore improved by the incorporation of the styrene monomer. A dry blend containing 1 part by weight (pt. wt.) Ex3 to 100 pts. wt. PVC resin, plus stabilisers (calcium and zinc salts), lubricant, calcium carbonate, titanium dioxide and blowing agent was processed in a single screw extruder at 140/170/185[deg] C and extruded to give a product with a regular surface and a density of 0.52. The use of C3 instead of Ex3 gave a product with a very irregular, wavy surface (density 0.56).</p> |
