Impact weatherable core shell

In the case of acrylic molding sheets and semi-fmished products, Wacker have elaborated a product concept based on silicone core-shell technology, which enables the manufacture of highly transparent particle-modified materials with improved RT and low-temperature (-40 C) impact resistance and high weatherability [4]. Other transparent plications (e.g., epoxy resins, polycarbonates) are showing encouraging results, too. 

Predesigned particles of impact modifiers are based on core-shell technology. Core is involved in impact modification and shell improves adhesion between PVC and impact modifier particles.Three major combinations are used methacrylate-butadiene-styrene, MBS, which has a core made out of butadiene-styrene copolymers and shell made out of methylmethacrylate-styrene copolymer, acrylic impact modifiers, AIM, which have a core made out of acrylic and shell from polymethylmethacrylate, and silicone-acrylic have multilayer structures with silicone-acrylic in the core. MBS has excellent compatibility with PVC, similar to ABS, which is used as an impact modifier of PVC, as well. In both cases of ABS and MBS, weather resistance is lacking, therefore they are used for indoor applications only. At the same time, MBS gives translucent to crystal clear products, whereas with AIM, only translucent products are possible. In order to improve optical properties of AIM, it has to be reformulated. For transparent products, the core is made out of acrylic-styrene copolymers. Comparing silicone and all acrylic impact modifiers, PVC containing silicone-based products has superior low temperature impact properties. The incorporation of silicone into an acrylic impact modifier provides excellent weatherability, and thermal stability. It has shown improved retention of impact after outdoor weathering in PVC. ... 

Acrylate core-shell rubbers (PMMA-g-BuA) Weatherability, clarity, impact, processability 53 69 192 1,041... 

Recently, latexes were prepared with a crosslinked core, crosslinked interlayers, and a crosslinked shell. A seed latex was overcoated five times with various combinations of methyl methacrylate and butyl acrylate, allyl methacrylate serving as the crosslinker.Moldable products with good transparency, stress-clouding resistance, as well as impact and weathering resistance were attained. The subject was recently reviewed. 

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