What kind of plastic is used for the shell of medical instruments?

PE, PP, ABS, PVC, PS plastic is a commonly used chemical raw materials, is made of a certain type or several monomers in certain reaction conditions polymerization of polymer organic materials, due to its lightweight, inexpensive, excellent performance characteristics, in the national economy occupies an important part. First, the conventional varieties of plastics and classification in daily life, we can directly contact or perceived plastic, most of the conventional general-purpose plastics, including five categories: PE, PP, ABS, PVC, PS, these five categories of plastics accounted for the majority of the use of plastic raw materials, the rest of the basic can be categorized as a special variety of plastics, such as: PPS, PPO, PA, PC, POM, etc., which The amount of daily life products is very small, mainly used in the engineering industry, national defense science and technology and other high-end areas, such as automotive, aerospace, construction, communications and other fields. Plastics are categorized according to their plasticity and can be divided into thermoplastics and thermosets. Usually, thermoplastic products can be recycled, while thermoset plastics can not. According to the optical properties of plastics, they can be divided into transparent, semi-transparent and opaque raw materials, such as PS, PMMA, AS, PC, etc. belong to transparent plastics, while most other plastics are opaque plastics. There are many other ways to categorize plastics, not introduced here. Second, the performance and use of commonly used plastic varieties 1, polyethylene: commonly used polyethylene can be divided into low-pressure polyethylene (HDPE), high-pressure polyethylene (LDPE) and linear high-pressure polyethylene (LLDPE). Among the three, HDPE has better thermal, electrical and mechanical properties, while LDPE and LLDPE have better flexibility, impact properties, film-forming properties, etc. LDPE and LLDPE are mainly used for packaging film, agricultural film, plastic modification, etc., while the use of HDPE is more widely used, film, tubing, injection of daily necessities in many areas. 2, polypropylene: relatively speaking, more varieties of polypropylene, the use of more complex, a wide range of fields, varieties are mainly homopolymer polypropylene (homopp), block *** polypropylene (copp) and random *** polypropylene (rapp), according to the different uses, homopolymer is mainly used in wire drawing, fiber, injection, BOPP film and other fields, *** polypropylene is mainly used in Household appliances injection parts, modified raw materials, daily injection products, tubes, etc., atactic polypropylene is mainly used for transparent products, high-performance products, high-performance tubes and so on. 3, polyvinyl chloride: due to its low cost, the product has the characteristics of self-flame retardant, it is widely used in the field of construction, especially sewer pipes, plastic steel doors and windows, plates, artificial leather and other most widely used. 4, polystyrene: as a transparent raw material, in the case of transparent demand, a wide range of uses, such as automotive lampshades, daily transparent parts, transparent cups, cans and so on. 5, ABS: is a wide range of engineering plastics, with outstanding physical and mechanical and thermal properties, widely used in household appliances, panels, masks, combinations, accessories, etc., especially household appliances, such as washing machines, air conditioners, refrigerators, fans, etc., the dosage is very large, and in addition in the plastic modification, the use of a wide range of applications. Third, the identification of commonly used plastics 1, density method: examining the density of various plastics, liquid as a medium, the test of its plastic in the liquid medium of the sinking and floating to roughly identify the major categories of plastics, such as a piece of plastic in the water, floating on the surface of the water can be concluded that the raw material is not PVC (because of the density of PVC > 1). 2, combustion method: the main examination of the color of the flame and the smell and smoke emitted during combustion, in general, polyolefin raw materials combustion flame is blue or light blue, the smell is relatively mild and light, smoke was white, and most of the raw materials with benzene or chlorine combustion is prone to black smoke, a strong smell. In addition, such as PE, PP, drip burning phenomenon, while PVC and other non-drip burning, but there is a self-extinguishing phenomenon. 3, optical method: the main examination of the transparency of raw materials, generally used transparent raw materials: PS, PC, PMMA, AS; translucent raw materials: PE, random **** poly PP, homopolymerization of PP, soft PVC, transparent ABS, etc., other raw materials are basically opaque. 4, color identification method: in general, without additives raw materials, if itself contains double bonds, the color will be slightly yellow, such as ABS, due to butadiene *** polymerization, polymerization of polymers still contain double bonds, so it will be slightly yellow. Most of the other methods of identification with the help of various instruments, such as infrared spectroscopy, mass spectrometry, nuclear magnetic **** vibration, differential thermal scanning, thermal analysis.

Polyvinyl chloride (PVC) Performance: polyvinyl chloride is divided into soft, hard two kinds: hard polyvinyl chloride, high mechanical strength, electrical performance is excellent, acid and alkali resistance is very strong, chemical stability is very good; shortcomings: softening point is low. Soft polyvinyl chloride tensile strength, flexural strength, impact strength, impact toughness, etc. are hard polyvinyl chloride is low, while the elongation of the break is higher. Uses: hard PVC products are tubes and rods, plates, welding rods, centrifugal pumps, ventilators, wheel oil pipes, acid and alkali pumps, valves and containers. Soft PVC products are storage tanks, sheet, film, wire insulation, window cover, acid and alkali resistant hose. Polyethylene (PE) Performance: divided into high-pressure, medium-pressure and low-pressure polyethylene three. High-pressure polyethylene is flexible; low-pressure polyethylene is hard, good cold resistance, and remains soft at -70℃. It has high chemical stability and is resistant to acids, alkalis and organic melts. It has outstanding electrical properties and good radiation resistance. Coated on metal surface by flame spraying method or electrostatic spraying method, it can achieve the purpose of friction reduction and corrosion prevention. The disadvantage is that the mechanical strength is not high, the heat distortion temperature is very low, so it can not withstand higher loads. Uses: corrosion-resistant lining of chemical equipment and storage tanks, chemical corrosion-resistant pipes, valve parts, bushings, roller frames, to replace copper and stainless steel. Insulation for high frequency underwater cables or general cables. Transistor radio magnet bar antenna clamp frame. Polystyrene (PS) Performance: a certain degree of mechanical strength, chemical stability and electrical properties are better, good light transmission, good coloring, and easy to form, it is characterized by almost completely water-resistant, the lack of heat resistance is lower, brittle, and its products are easy to crack due to the internal stress, can only be used at low loads and low temperatures (60 ~ 75 ℃). Uses: various instrument shells, skeletons, instrument indicators, lampshades, automobile lampshades, chemical storage tanks, acid transport tanks (especially such as hydrofluoric acid), chemical instrument parts, telecommunications parts, due to good transparency, can be used as optical instrument parts and lenses. High Impact Polystyrene (HIPS) Performance: Compared with polystyrene, it has higher toughness and impact strength, the rest of the properties are basically similar, good molding process. Uses: a variety of instruments, transistor radio shell, coil skeleton, textile yarn tube, television structural parts, agricultural water board accessories and small plastic pipe, plate, etc.. Polystyrene modified plexiglass Performance: good transparency. Mechanical strength is also high, a certain degree of heat resistance, cold resistance and weather resistance, corrosion resistance, good insulation. Product size stability, easy to form. Disadvantages are brittle, soluble in organic solvents, as a light-transmitting materials, surface hardness is not enough, easy to rub hair, in terms of its comprehensive performance, more than polystyrene and other general plastics. Uses: It is used to manufacture parts with certain transparency and strength, such as oil markers, oil cups, optical lenses, lenses, equipment signboards, transparent pipes, automobile lamps and transistor radio dials and electrical insulation parts. Styrene acrylonitrile **** polymer (AS or SAN) Performance: higher impact strength than polystyrene and excellent heat resistance, oil resistance, chemical resistance. Such as it can be very good resistance to certain hydrocarbons that make polystyrene stress cracking. And the modulus of elasticity is one of the higher existing thermoplastics. Uses: Widely used in the production of oil-resistant, heat-resistant, chemical-resistant industrial products, as well as instrument panels, instrument frames, covers, battery boxes, junction boxes, a variety of switches and press gauges. Styrene acrylonitrile **** polymer (AS or SAN) Performance: higher impact strength than polystyrene and excellent heat resistance, oil resistance, chemical resistance. Such as it can be very good resistance to certain hydrocarbons that make polystyrene stress cracking. And the modulus of elasticity is one of the higher existing thermoplastics. Uses: Widely used in the production of oil-resistant, heat-resistant, chemical-resistant industrial products, as well as instrument panels, instrument frames, covers, battery boxes, junction boxes, a variety of switches and gauges. Styrene-butadiene-acrylonitrile*** polymer (ABS) Performance: ABS is a "tough, hard, rigid" material. With high impact toughness and mechanical strength, dimensional stability, chemical resistance and good electrical properties, easy to form and mechanical processing and other characteristics. In addition, the surface can also be chromium-plated, becoming a common material for plastic coated metal. In addition, ABS and # 372 plexiglass with good connectivity, can be used for two-color molding plastic parts. Uses: in the mechanical industry system used to manufacture cams, gears, pump impellers, bearings, motor housing, instrument cases, battery tanks, tank shells, handles, refrigerator liners, etc., the automotive industry used to manufacture the driving plate, hot air conditioning, tube heaters, etc., but also available for the manufacture of television transistor radio shell. Polypropylene (PP) Performance: the main feature of polypropylene is the density is small, its mechanical properties are better than low-pressure polyethylene, and has outstanding rigidity, heat resistance is better. Can be used above 100 ℃. Basically does not absorb water, and has good chemical stability, except for concentrated sulfuric acid, concentrated nitric acid, almost all very stable. Excellent high-frequency electrical properties, and is not affected by temperature, easy to form. Disadvantage is not high enough wear resistance, molding shrinkage, low temperature is brittle, heat distortion temperature is also low. Uses: Can do all kinds of mechanical parts, such as flanges, gears, joints, pump impellers, automobile parts. Chemical pipeline and container equipment. And can be used as lining, surface coating, recording tape, medical instruments and surgical instruments. Polycarbonate (PC) Performance: Impact strength is particularly outstanding. In general thermoplastic resin is better. Higher modulus of elasticity, minimal influence by temperature, heat-resistant temperature of 120 ℃. Cold-resistant up to -100 ℃ pick embrittlement. High dimensional stability. Corrosion resistance, wear resistance are good. But there is a high temperature sensitivity to water. Uses: used to manufacture gears, worm gears, racks, cams, mandrels, bearings, gaskets, rivets, pump impellers, automobile carburetor parts, lamp shades, flash lamp shades, throttle valves, lubricating oil pipelines, a variety of shells, containers, refrigeration and cooling device parts, electrical wiring boards, coil bobbins, acidic battery tanks and high-temperature lenses and so on.