ABS plastic is a terpolymer of acrylonitrile (A)-butadiene (B)-styrene (S). It combines the properties of three components: acrylonitrile has high hardness and strength, heat resistance and corrosion resistance; butadiene has impact resistance and toughness; and styrene has a high gloss surface, easy coloring and easy processing. The properties of the above three components make ABS plastic a "hard, tough and rigid" thermoplastic with good overall performance. ABS plastics can be molded by injection, extrusion, thermoforming, sawing, drilling, filing, grinding, etc., and can be bonded with organic solvents such as trichloromethane, and can be coated and plated for surface treatment. ABS plastic is also an ideal substitute for wood and construction materials, etc. ABS injection molding plastic is strong, light, hard, smooth, easy to clean, dimensionally stable, creep resistant, and suitable for electroplating treatment. ABS plastics are used in a wide range of industrial applications, and ABS injected products are often used to make shells, cases, parts, toys and so on. Extruded products are mostly sheets, rods, tubes, etc., which can be hot pressed, compounded and made into models. [2]
Molecular structure
The structure of ABS resin has a graft copolymer with elastomer as the main chain and a graft copolymer with a hard ABS resin substance as the main chain; or a mixture of rubber elastomer and hard ABS resin. In this way, different structures show different properties, with the elastomer showing the toughness of rubber and the hard ABS resin showing rigidity, and several varieties of high impact, medium impact, general impact and special impact types can be obtained. Specifically, as the content of rubber component B (generally 5% to 30%) increases, the elasticity and impact resistance of the resin increases; however, the tensile strength, fluidity, and weather resistance decrease. Resin component AS content (generally 70% to 95%) content increases, it can improve the surface gloss, mechanical strength, weather resistance, heat resistance, corrosion resistance, electrical properties, processing properties, etc.. And impact strength, etc. is to decline. The ratio of A and B in the resin component is 30%~35%/80%~65% respectively.
Main characteristics
ABS injection molding manufacturer is a terpolymer of acrylonitrile, butadiene and styrene, with A representing acrylonitrile, B representing butadiene and S representing styrene. After practical use, ABS plastic pipe is found to be resistant to sulfuric acid corrosion, and crushing rupture when encountering sulfuric acid.
It has three compositions that give it good performance; acrylonitrile gives ABS resin chemical stability, oil resistance, some stiffness and hardness; butadiene makes it toughness, impact and cold resistance are improved; styrene makes it good dielectric properties and presents good processability.
Most ABS is non-toxic, impervious to water, but slightly permeable to water vapor, low water absorption, room temperature immersion for a year water absorption rate of no more than 1%, and physical properties do not change. ABS resin products can be polished on the surface, can get a high gloss products. The strength of ABS resin is 3-5 times higher than that of general plastics.
ABS has excellent overall physical and mechanical properties, good low temperature impact resistance. Dimensional stability. Electrical properties, abrasion resistance, chemical resistance, dyeing, finished product processing and machining are better. ABS resin is resistant to water, inorganic salts, alkalis and acids, insoluble in most alcohols and hydrocarbon solvents, and readily soluble in aldehydes, ketones, esters and certain chlorinated hydrocarbons. ABS resin has a low heat deflection temperature is combustible, and heat resistance is poor. The melting temperature is 217~237°C and the thermal decomposition temperature is above 250°C. Today's market modified ABS material, many are adulterated with water mouth material, recycled material. This leads to the customer molding product performance is not very stable plastic injection molding services.
(1) Material performance
1. better overall performance, higher impact strength, chemical stability, good electrical properties.
2. good fusion with 372 plexiglass, made of two-color plastic parts, and can be surface chrome plated, spray paint treatment.
3. having high impact resistance, high heat resistance, flame retardant, reinforced, transparent and other levels.
4. flow is a little worse than HIPS, better than PMMA, PC, etc., good flexibility.
5. suitable for making general mechanical parts, wear-resistant parts, transmission parts and telecommunication parts.
(2) molding properties
1. amorphous material, medium fluidity, moisture absorption, must be fully dried, the surface requires glossy plastic parts must be preheated and dried for a long time 80-90 degrees, 3 hours.
2. preferably take high material temperature, high mold temperature, but the material temperature is too high easy to decompose (decomposition temperature is > 270 ℃). For high precision plastic parts, the mold temperature should be 50-60℃, for high gloss, heat resistant plastic parts, the mold temperature should be 60-80℃.
3. to solve the problem of water trap, need to improve the fluidity of the material, take high material temperature, high mold temperature, or change the water entry level and other methods.
4. if forming heat-resistant or flame-retardant grade material, the plastic decomposition material will remain on the surface of the mold after 3-7 days of production, resulting in a shiny mold surface, which needs to be cleaned up in time, and the exhaust position on the mold surface needs to be increased.
5. fast cooling speed, mold casting system should be coarse and short as the principle, it is advisable to set cold material cavity, the gate should be taken large, such as: direct gate, disc gate or fan gate, etc., but should prevent the increase of internal stress, if necessary, adjustable gate can be used. The mould should be heated and wear-resistant steel should be used.
6. the material temperature has a great influence on the quality of plastic parts, too low material temperature will cause lack of material, surface lusterless, silver wire disorder too high material temperature is easy to overflow edge, silver wire dark strip, plastic parts discoloration and blistering.
7. injection molding temperature has a great impact on the quality of plastic parts, mold temperature is low shrinkage, elongation, impact strength, flexural, compressive, tensile strength is low. When the mold temperature exceeds 120℃, the plastic parts are slow to cool, easy to deform and stick to the mold, difficult to demold, and long molding cycle.
8. the molding shrinkage is small, easy to melt cracking, stress concentration, so molding should be strictly controlled molding conditions, molding plastic parts should be annealed after treatment.
9. high melting temperature, high viscosity, insensitive to shear action, for plastic parts larger than 200 grams, screw injection machine should be used, the nozzle should be heated, it is desirable to use open and smooth extension type nozzle, injection speed in high speed.
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