ABS plastic is a terpolymer of acrylonitrile (a) - butadiene (b) - styrene (s). Acrylonitrile has high hardness and strength, heat resistance and corrosion resistance; butadiene has impact resistance and toughness; styrene has high gloss, easy coloring and easy processing. The properties of the above three components make ABS become a kind of thermoplastic with good comprehensive properties of "hard, tough and rigid". By adjusting the proportion of three components of ABS, its performance will change to meet the requirements of various applications, such as high resistance ABS, heat resistant ABS, high gloss ABS, etc. ABS plastics have good processability. They can be molded by injection, extrusion, hot forming, etc. they can be machined by sawing, drilling, filing and grinding. They can be bonded with organic solvents such as chloroform. They can also be used for surface treatment such as coating and electroplating. ABS plastics are also ideal wood substitutes and building materials. ABS plastic has high strength, light weight, high surface hardness, very smooth, easy to clean, stable size, good creep resistance, so it is suitable for electroplating. Its application field is still expanding. ABS plastics are widely used in industry. ABS injection products are commonly used to make shells, boxes, parts, toys and so on. Most of the extruded products are plates, bars and pipes, which can be hot pressed, processed and modeled.
ABS resin is the most widely used polymer with the largest output. It combines all kinds of properties of Pb, pan and PS, and has excellent mechanical properties of toughness, hardness and rigid phase balance. ABS is a terpolymer of acrylonitrile, butadiene and styrene. A represents acrylonitrile, B represents butadiene and s represents styrene. After practical use, it is found that ABS plastic pipe is not resistant to sulfuric acid corrosion, and will be crushed and cracked when meeting sulfuric acid.
Because of its three components, it has good performance; acrylonitrile gives ABS resin chemical stability, oil resistance, certain stiffness and hardness; butadiene improves its toughness, impact and cold resistance; styrene makes it have good dielectric properties and good processability.
Most ABS are nontoxic and impermeable, but slightly permeable to vapor, with low water absorption. The water absorption rate of ABS is less than 1% in one year after immersion at room temperature, and the physical properties remain unchanged. The surface of ABS resin products can be polished to obtain high gloss products. 3-5 times higher than the strength of general plastics.
ABS has excellent comprehensive physical and mechanical properties and good low temperature impact resistance. Dimensional stability. Electrical properties, wear resistance, chemical resistance, dyeability, finished product processing and mechanical processing are better. ABS resin is resistant to water, inorganic salt, alkali and acid, insoluble in most alcohols and hydrocarbon solvents, but easily soluble in aldehydes, ketones, esters and some chlorinated hydrocarbons. ABS resin has low thermal deformation temperature, flammability and poor heat resistance. The melting temperature is 217 ~ 237 ℃, and the thermal decomposition temperature is above 250 ℃. In today's market, many modified ABS materials are doped with nozzle materials and recycled materials. As a result, the performance of customer molding products is not very stable.
(1) Material performance
It has good comprehensive properties, high impact strength, chemical stability and good electrical properties;
It has good fusibility with 372 PMMA and can be made into two-color plastic parts, and can be plated with chromium and sprayed with paint;
There are high impact, high heat resistance, flame retardant, reinforced, transparent and other grades;
The fluidity is worse than hips, better than PMMA, PC, etc;
It is suitable for making general mechanical parts, wear-resistant parts, transmission parts and telecommunication parts.
Amorphous material, with medium fluidity and high moisture absorption, must be fully dried. The plastic parts with glossy surface must be preheated and dried for 80-90 degrees for 3 hours;
High material temperature and mold temperature should be selected, but if the material temperature is too high, it is easy to decompose (decomposition temperature is > 270 ℃). For high precision plastic parts, the mold temperature should be 50-60 ℃, for high gloss and heat-resistant plastic parts, the mold temperature should be 60-80 ℃;
In order to solve the problem of water inclusion, it is necessary to improve the fluidity of materials, such as high material temperature, high mold temperature, or changing the water level;
For example, if the heat-resistant or flame-retardant materials are formed, there will be residual plastic decomposition on the mold surface after 3-7 days of production, which will cause the mold surface to be bright. Therefore, the mold should be cleaned in time, and the exhaust position should be increased on the mold surface;
The cooling speed is fast, the pouring system of the mould should be based on the principle of thick and short, cold material hole should be set and the gate should be large, such as direct gate, disc gate or fan gate, etc., but the increase of internal stress should be prevented, and the adjustable gate can be used if necessary. The mould should be heated and wear-resistant steel should be selected;
The material temperature has a great influence on the quality of plastic parts. If the material temperature is too low, the surface will be dull, and the silver wire will be disordered. If the material temperature is too high, it is easy to overflow the edge, and there will be silver wire dark stripes, and the plastic parts will change color and bubble;
When the mold temperature is low, the shrinkage, elongation, impact strength, bending, compression and tensile strength are low. When the mold temperature is over 120 ℃, the cooling of the plastic parts is slow, easy to deform and stick to the mold, difficult to demould and long molding cycle;
Because of its small shrinkage, melting cracking and stress concentration, the molding conditions should be strictly controlled and the plastic parts should be annealed after molding;
High melting temperature, high viscosity, and insensitive to shear action. For plastic parts larger than 200g, screw type injection machine should be used, nozzle should be heated, and open extended nozzle should be used, with medium and high injection speed.