PMMA / ABS alloy plate system
At present, for the PMMA / ABS alloy plate research can be divided into two systems.
① body method PMMA / ABS board
The main purpose is to improve the ABS weather resistance and scratch resistance, giving ABS more excellent coloring performance.
② emulsion PMMA / ABS board
The alloy has high transparency, excellent colorability and scratch resistance, is the most widely used PMMA / ABS alloy plate, while the basic research for the alloy more, but mostly confined to its phase Separation evolution and rheological properties, mechanical properties of the relevant data less.
The following is a summary of the comprehensive performance of PMMA / ABS alloy sheet in the light of practical work and literature. The purpose is to give readers a more intuitive understanding of PMMA / ABS alloy, and to provide some information on the problems encountered in the preparation and use of PMMA / ABS alloy. Reference.
Properties of PMMA / ABS Alloy Plate
As we all know, because of the presence of unsaturated double bond in ABS, its products weatherability is poor, especially in the use of light-colored products and placed in the process prone to yellowing and whitening phenomenon, affecting the appearance of products, and paragraph lead to a significant decline in mechanical properties, Material loss of use price quietly. In order to improve the weatherability of ABS, the usual method is to add a weathering agent, but the cost will be significantly increased and the weatherability with the increase of light time to improve its limited effect, and through the preparation of PMMA / ABS alloy, the weather resistance was significantly improved . The ABS / PMMA alloy plate's weathering curve, PMMA addition of 20%, material △ E decreased by 68%, and with the increasing content of PMMA gradually decreased, but note that PMMA melt viscosity, low toughness, Therefore, the combination of PMMA and weathering agent can achieve better weatherability under low PMMA addition, and maintain the processing and using performance of the material.
Compared with PC / ABS, PMMA / ABS has an unparalleled weathering advantage, in the same test conditions, PMMA content of 50% of the PMMA / ABS alloy ABS light of its color difference is about 1/30, PC / ABS Of the PMMA / ABS alloy is particularly suitable for light-colored products with high weather resistance requirements, such as outdoor billboards, fluorescent signs, etc., can make long-term products to maintain good appearance.
(2) impact performance
PMMA / ABS alloy plate in the appliance industry is more widely, especially the liquid crystal display shell. Due to the complexity of the product design, product toughness in the buckle and weld line area is poor, one of the most concerned about the performance of the user. In the PMMA / ABS system, the toughness of the raw material itself, such as ABS rubber content, PMMA type, PMMA content and AN content in matrix SA1N (AN content affects the compatibility of ABS and PMMA) . The toughness of the alloy increases with the increase of the PMMA content, and the high viscosity PMMA improves the toughness of the alloy more obviously, and the PMMA content of the brittle - ductile transition of the high - viscosity PMMA decreases. The SEM micrographs show that the high-viscosity PMMA-induced shear band can be absorbed by the yield of matrix, and the toughness of the material is improved.
PMMA / ABS composite plastic plate
The results show that the toughness of the alloy increases first and then decreases with the increase of the content of PMMA, and the maximum value appears when PMMA = 50%, which may be attributed to the phase inversion of SAN / PMMA alloy and the decrease of the toughness of PMMA as brittle continuous phase.
In addition, in the SAN / PMMA / toughening agent ternary system, the type of flexibilizer and rubber particle size is also a major factor affecting the toughness of the material, but the toughening agent is generally expensive, need to consider the PMMA type, mixed And select the appropriate toughener in order to obtain cost-effective PMMA / ABS material.
(3) other properties
With the thin-walled LCD, lightweight and beautiful, the market's overall performance requirements of the material more and more, the current mainstream of the LCD industry materials are common high-light ABS, halogen-free flame retardant PC / ABS and PMMA / ABS Alloy plate. Universal high-gloss ABS for the surface hardness of the lower parts, such as TV base and rear shell, the cost and processing performance with the other two materials unparalleled advantages; halogen-free flame retardant PC / ABS is currently mainly used for LCD The former shell, both flame retardant and high impact resistance, but its obvious shortcomings: forming large parts prone to weld line, easy to scratch, high molding temperature easily lead to degradation of materials and so on.
In recent years, the development of PMMA / ABS alloy plate with high scratch resistance and easy molding characteristics, the surface hardness up to H-level, eliminating the need for the second spray, this alone can save customers 15% to 20% of the cost, and In addition, PMMA and SAN glass transition temperature is higher, the alloy is particularly suitable for E-Mold molding, to solve the complex flow channel and thin wall caused by the flow marks and welding lines of the risk. PMMA / ABS is gradually replacing the halogen-free flame-retardant PC / ABS as the first choice for high-end home appliance industry with the appearance of products more and more customers.