ABS resin is acrylonitrile-butadiene-styrene copolymer, as one of the plastic varieties with excellent comprehensive performance, ABS on the one hand, the market application is constantly developing, on the other hand, through the development of new varieties and technical modification and alloy research, it is increasingly becoming the sixth largest engineering plastics, especially through modification, ABS derived more new varieties. It can be mixed with a variety of resins into alloys, many types, widely used, is the main modified plastics.

ABS physical properties

ABS is light yellow granular or beaded opaque resin, non-toxic, tasteless, low water absorption, with good comprehensive physical and mechanical properties, such as excellent electrical properties, wear resistance, dimensional stability, chemical resistance and surface luster, and easy to process molding. The disadvantages are weather resistance, poor heat resistance, and flammable.

ABS plastic mechanical properties

ABS has excellent mechanical properties, its impact strength is very good, can be used at very low temperatures; ABS has excellent wear resistance, good dimensional stability, and oil resistance, and can be used for bearings under moderate load and speed. The creep resistance of ABS is larger than PSF and PC, but smaller than PA and POM. The bending strength and compressive strength of ABS are poor among plastics. The mechanical properties of ABS are greatly affected by temperature.

ABS application range

ABS High luster ABS is used for vacuum cleaners, fans, air conditioners, telephone and other household appliances, by controlling the rubber particle size R+(small) in ABS, low luster ABS is used for instrument panels, instrument covers, columns and other automotive interior parts, with coarse packing method to make the surface micro-shrinkage, reduce the surface luster.

Types and characteristics of ABS

Fireproof (flame retardant) grade ABS

ABS belongs to flammable materials, and belongs to HB level according to UL94 standard. ABS burns fast when it is on fire, and emits a lot of poison gas and black smoke, which is not conducive to practical application. With the advancement of science and technology and the improvement of quality of life, people's safety awareness is becoming stronger and stronger, and China has put forward strict fire and flame retardant requirements for the plastic materials used in automobiles, buildings, household appliances, office supplies and other aspects, and formulated corresponding technical standards and specifications, so the research on flame retardant ABS has a very important significance.

There are three main ways to reduce the flammability of ABS resin:

1, the use of flame retardant polymer and ABS blend, such as CPE, PVC;

2, chemical modification of the existing ABS, such as adding tribromostyrene as the fourth monomer to prepare four components of ABS;

3, through the general method to add flame retardants to ABS, including inorganic flame retardants (such as MoO3) and organic flame retardants (such as halogen compounds, phosphorus flame retardants). The flame retardant type has an efficient flame retardant effect, but other properties may not be good (such as aging, high cost). Chemically modified ABS requires a specific production process, the process is more complex, and the third method strikes a balance between cost and performance, and has more flexibility in designing multi-functional materials. At present, the flame retardant modification of ABS materials is mainly based on the addition of efficient halogenated flame retardants.

Heat resistant (high temperature resistance) grade ABS

Heat resistant ABS resin thermal deformation temperature is generally in 90~105¡æ, with good heat resistance, toughness and fluidity. Can be used for automobile door, rear wheel cover inner plate, panel, etc., used in the field of home appliances, such as microwave oven, rice cooker, hair dryer and so on. The heat resistance of ABS can be improved by reducing the rubber content, increasing the SAN molecular weight and acrylic content, but the method of developing heat-resistant ABS by adding heat-resistant monomers or heat-resistant auxiliaries is more concerned by people. Introduction of &alpha in ABS resin; -methylstyrene (MS), maleic anhydride

(MA) and maleimide (MI) can improve the heat resistance of ABS.

There are two main ways:

1. Copolymerization of styrene and acrylonitrile with MS and MI as the third monomer can increase the rigidity of matrix resin and increase its Tg. The copolymer of MA and AN has better heat resistance than SAN with the same AN content, and its Vica softening temperature is 123¡æ and 103¡æ, respectively. The chemical resistance and physical properties of the two copolymer are similar, and the production method can be used universally. The Ms-based material is yellowish in color than the styrene-based one. In actual production, MS only partially replaces styrene to get SMSAN copolymer. The substitution ratio depends on the heat resistance requirements.

2, the better heat resistance of styryl-maleic anhydride copolymer (SMA) or styryl-maleimide copolymer (SMI) as a blend component added to ABS resin. The Veka softening point temperature of SMA can reach 150¡æ. However, SMA is unstable at higher temperatures. It will release carbon dioxide, so it must be released before it is stable enough to be machined below 260 ¡ã C, otherwise the parts will have radioactive streaks. SMA can be stabilized by adding 1% hindered phenol antioxidant and thioester synergist. SMI can be used in situations where heat resistance is required beyond what SMA and MS can provide. The copolymerization process of styrene and MI is the same as that of SAN. SMI can also be prepared by the reaction of SMA with ammonia or amine and imidezation. SMI has good thermal stability at high temperatures and does not produce radioactive streaks.

Antistatic grade ABS

SAN resistance should be AN polarity property and slightly lower than PS, but still has enough insulation. The surface static charge of ABS causes problems such as dust adsorption, demoulding difficulty and electrostatic discharge in processing, transportation and use. Therefore, ABS products need to have a certain conductivity to prevent internal discharge, and even shield the external electromagnetic interference to precision electronic components. Adding antistatic agent can prevent static charge from producing or dissipating static charge, which is the main method for preparing antistatic grade ABS.

Antistatic agent can be added prior to ABS processing or during ABS processing.

According to the way of addition, the types of antistatic agents are as follows:

(1) External antistatic agents, in the form of water or alcohol solution coated on the surface of ABS products, the most commonly used is quaternary ammonium salt. Quaternary ammonium salt can reduce the surface resistance of the parts, but it is easy to be removed during the use and cleaning of the parts, so it is widely used for short-term purposes such as preventing ash accumulation of the display parts.

(2) antistatic agent, added during ABS processing, the addition amount is small (0.1%~3%), and a certain degree of compatibility with ABS. The internal antistatic agent is divided into migration antistatic agent and permanent antistatic agent. Migration antistatic agent is ionic or non-ionic surfactant. The hydrophobic part is limited compatible with ABS, and the hydrophilic part can adsorb water to increase the surface conductivity after migrating to the surface inside ABS. After the antistatic agent on the surface is removed, the internal antistatic agent can continue to migrate to the surface until it is completely exhausted, so the use time is longer than that of the external electrostatic agent. Permanent antistatic agents do not migrate, including highly conductive fillers (such as carbon black, metal-coated carbon fiber, stainless steel wire), hydrophilic polymer materials (such as polyoxyethylene copolymer) and conductive polymer materials (such as polypropylene, polythiophene). Among them, hydrophilic polymer materials are low, mainly used in office automation equipment. Conductive fillers are not suitable for marking the use of color, transparency and electronic fields.

Common anti-static ABS table below

Anti-static ABS typical performance

Under the same formula conditions, blending equipment and blending process and injection molding process and other production conditions have a great impact on the performance of the final product, Such as mixing temperature, residence time, screw speed, extrusion yield, injection molding temperature, mold temperature, etc., will directly affect the performance of the final product.

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