Transparent ABS sheets are products with the highest added value among modified ABS sheet and are widely used in fields with transparency requirements. There is a huge demand for transparent ABS sheet in the domestic market, but due to its complex preparation process, high equipment costs, and high haze value, it is expensive and greatly increases the cost of using PMMA/ABS sheet.
In recent years, driven by the market, alloying PMMA and ABS to impart transparency to ABS sheet has become a research hotspot, which has greatly satisfied market demand and reduced material costs.
Ordinary ABS sheets are composed of two incompatible phases, namely the polybutadiene rubber graft copolymer phase and the SAN resin phase. The light scattering effect caused by the difference in refractive index between different microphases of ABS sheet causes the material to lose its transparency. The difference between the rubber particle size and the refractive index of the two phases determines the transparency of the ABS sheet. If the particle size is small enough to be comparable to visible wavelengths, the two phases can be considered to be optically homogeneous, and the transparent PMMA/ABS sheet product will appear translucent. If the refractive indices are exactly equal, the product appears completely transparent.
The design principle of transparent PMMA/ABS sheet is to adjust the chemical structure of the material through blending, copolymerization and other means to reduce the refractive index difference between the rubber and plastic phases while maintaining its advanced structure of microscopic phase separation. Theoretically, as long as the particle size of the latex used to make transparent PMMA/ABS sheet is smaller than the wavelength of visible light, 370nm, it can be transparent.
The design principle of transparent PMMA/ABS alloy sheet is similar to that of transparent ABS sheet. In order to match the refractive index between components, PMMA/ABS alloys usually contain three components: SAN, PMMA, and toughening agent. The key technology to obtain high transparency is to select appropriate raw materials. Commercial transparent ABS sheet usually use tougheners with particle sizes ranging from 70 to 400nm. The toughening agent with a particle size of 150~300nm gives the PMMA/ABS sheet both transparency and toughness. Therefore, when designing PMMA/ABS alloy sheets, we must select appropriate raw materials according to the product's requirements for light transmittance, and optimize the formula of PMMA/ABS sheet through specific experiments based on theoretical calculations, so that we can get twice the result with half the effort.
The key indicators to measure the transparency of PMMA/ABS sheet include light transmittance and haze. Relevant data are obtained by calculating the scattering loss of light after passing through the sample. In practical applications, many people confuse the transmittance and haze of PMMA/ABS sheet. In fact, these two indicators measure the transparency of PMMA/ABS sheet from different angles.
In order to better distinguish the light transmittance and haze of PMMA/ABS sheet, we divide the materials into four types.
①High transmittance, low haze, such as PMMA;
②High light transmittance and high haze, such as astigmatism PMMA;
③Low transmittance and low haze, such as dyed PMMA;
④Low transmittance, high haze, such as ABS 0
In addition to the properties of the PMMA/ABS sheet itself, the light transmittance is related to the surface roughness of the product. The smoother the surface, the fewer defects, the higher the light transmittance, and the clearer the visible image; while haze is related to the product molding process, such as PMMA If the molding temperature of the ABS board is too high and the shear is too large, it can easily cause phase separation or degradation of the PMMA/ABS sheet, which will appear as white haze on the product, and the material will change from transparent to milky white or turbid. In severe cases, it will cause the PMMA/ABS board to deteriorate. Transparency is completely lost.
In recent years, the market for transparent PMMA/ABS sheet has grown increasingly, mainly involving home appliances, OA, packaging materials, toys, vacuum cleaner casings and other fields. The main manufacturers of transparent PMMA/ABS sheets include JiangSu Compound Interest Technology Materials Co.,Ltd. and Yangzhou Chengsen Plastic Co., Ltd.. Yangzhou Chengsen Plastic Co., Ltd. has successfully developed transparent PMMA/ABS alloy sheet in cooperation with several major universities in China since 2007, and developed ultra-high flow alloy materials to provide customers with welding lines and fogging solutions.