VISIOMER® – methacrylate monomers for plastics
Methacrylate monomers are used in the production and modification of a wide variety of polymers – mainly in cast sheet, methacrylate molding compounds and graft copolymers as impact modifiers for thermoplastics.
Further application fields include artificial marble, PVC modifiers and PVC plastisols. Molding compounds based on unsaturated polyester resins may also contain multifunctional methacrylates as crosslinking agents.
In addition, methacrylates are used as comonomers to improve the performance of polymers in extrusion coating applications. Typical end-use applications, here, include liquid carton packaging, photographic paper, flexible and commercial packaging (e.g. coffee pouches).
ACRYLIC SHEET & MOLDING COMPOUNDS
PMMA (polymethyl methacrylate) stands out from other plastics due to its high light transmission, extremely long service life, and specific properties such as high resistance to UV light and weathering – as well as unlimited coloring options. In addition, PMMA shows the greatest surface hardness of all thermoplastics. It can be fabricated by means of all thermoforming methods, and therefore offers huge creative scope. Another major benefit is that PMMA is 100% recyclable, which makes an essential contribution to conserving natural resources. PMMA molding compounds are mainly used in the car industry for the production of headlamps, taillights and transparent panes for dashboards as well as household appliances, optical media (DVDs, lenses) and electronics. PMMA solid sheet is used mainly for illuminated advertising applications and shop interior displays. PMMA sanitary ware is suitable for the production of bathtubs and shower trays. VISIOMER® MMA is the principal monomer used for acrylic plastic casting. Multifunctional methacrylates, such as VISIOMER® 1,3-BDDMA, 1,4-BDDMA , EGDMA, PEG200DMA and TRGDMA, are used in smaller quantities to enhance thermostability and other mechanical properties of cast plastic sheets.
The term 'artificial marble' commonly refers to synthetic materials that mimic the texture of natural stone by compounding natural stone powder and/or minerals with resin components (such as acrylics, unsaturated polyesters, epoxies and the like) or cement, and adding various pigments and additives. Artificial marbles based on methacrylates are widely used as materials for kitchen countertops, wash basins, dressing tables, bathtubs, tabletops, walls, interior fixtures, etc. They combine outstanding aesthetics and high-end texture with excellent durability. VISIOMER® MMA is the most widely used monomer in this application field. Besides MMA, a specialty methacrylate such as VISIOMER® IBOMA can impart additional properties to the finished products, such as excellent dimension stability and hot water resistance. Multifunctional methacrylates such as VISIOMER® 1,3-BDDMA, 1,4-BDDMA EGDMA, TRGDMA, and TMPTMA are used to enhance thermal stability and other mechanical properties of cast plastic sheets.
Processing aids (PAs) based on acrylic copolymers have long been known in the PVC industry to control polymer fusion and melt rheology, increase melt elasticity and, in some cases, improve metal release. As a consequence of their high compatibility with PVC and high molecular weight, they mesh with PVC for improved melt properties. Most commercial processing aids are copolymers of VISIOMER® MMA and VISIOMER® n-BMA, with MMA as the major component. Their efficiency is controlled by adjusting molecular weight and glass transition temperature. PAs are used mainly for PVC building applications, such as window frames, panels, siding, fences, sign boards, roofing sheets, pipes, fittings, injection-molded parts and foamed products.
Copolymeric methyl methacrylate-butadiene-styrene (MBS) and methyl methacrylate-acrylonitrile- butadiene-styrene (MABS) impact modifiers are used as plastic additives for rigid plastics. They improve transparency, weather resistance (UV & heat) and mechanical properties (impact resistance) in PVC formulations. They are commonly added to many types of resins, such as polyvinylchloride (PVC), polycarbonates (PC), polyesters, polyacetals and epoxies. The modified resins are then processed into vinyl siding, window frames, pipe, fitting sheet, film, bottle, profile and injection-molded parts.
PVC plastisols are PVC powder emulsions in plasticizers, e.g. aromatic or aliphatic dicarbonic esters. Depending on the application envisaged and properties required, PVC/plasticizer ratios vary between 80:20 and 50:50. Without additives, PVC plastisols show only moderate adhesion to polar substrates, such as metal. Partially substituting the plasticizer with multifunctional methacrylates causes a substantial improvement in plastisol adhesion to these substrates. Moreover, peroxides added for plastisol gelation effectively initiate polymerization of the multifunctional methacrylates. This in turn leads to increased hardness and higher tensile strength in the end product. Shore hardness also depends on the type of multifunctional methacrylate used. It decreases in this order by up to 40% at the same monomer content: VISIOMER® 1,3-BDDMA > EGDMA > TRGDMA > PEG 200 DMA. The main applications for PVC plastisols containing multifunctional methacrylates as adhesion promoters and hardeners include the following: anti-noise compounds, car underseals, finish compounds for PVC flooring, and coil coatings.