Plastic products are the use of plastic as the main raw materials processed from the household supplies, industrial supplies collectively. including plastic with the raw materials of injection molding, blister and other products of all processes. Plastic is a kind of synthetic polymer material with plasticity. It and synthetic rubber, synthetic fiber form the current daily life indispensable three synthetic materials. Specifically, plastic is a natural or synthetic resin as the main ingredient, adding a variety of additives, in a certain temperature and pressure conditions can be molded into a certain shape, at room temperature to maintain the shape of the same material.
Compared with other materials, plastics have the following characteristics:
Plastic is a lighter material, with a relative density of 0.90-2.2. Obviously, can plastic float on the water? In particular, foam plastic, because of the micro-hole, the texture is lighter, the relative density is only 0.01. This feature allows plastics to be used in the production of products that require weight reduction.
Most plastics have good corrosion resistance to acid and alkali chemicals. In particular, commonly known as Plastic King Teflon (F4), its chemical stability is even better than gold, placed in the "Aqua Regia" in the boiling more than 10 hours will not degenerate. Because of its excellent chemical stability, F4 is an ideal corrosion resistant material. such as F4 can be used to transport corrosive and viscous liquid piping material.
Ordinary plastic is a bad conductor of electricity, its surface resistance, volume resistance is very large, with a number of 10,911,018 ohms. The breakdown voltage is large and the tangent value of dielectric loss angle is very small. Therefore, plastics in the electronic industry and machinery industry has a wide range of applications. such as plastic insulated control cable.
Generally speaking, the thermal conductivity of plastic is relatively low, equivalent to the steel 1/75-1/225, microcellular foam
Contains gas, its heat insulation, sound insulation, shockproof better. such as polyvinyl chloride (PVC) thermal conductivity is only 1/357 of steel, aluminum 1/1250. In the insulation capacity, single glass window than single glass aluminum 40%, double glass height 50%. The plastic form combined with insulating glass, in the residential, office buildings, wards, hotels, the use of winter to save heating, air-conditioning expenses in the summer, the benefits are very obvious.
Some of the plastic hard as stone, steel, and some soft as paper, leather, from the hardness of plastic, tensile strength, elongation and impact resistance, and other mechanical properties, a wide range of distribution, there is a great choice of use. Because of the small proportion of plastic, high strength, and thus has a higher strength. Compared with other materials, plastic also has obvious shortcomings, such as easy combustion, stiffness is not as high as metal, anti-aging, heat-resistant and so on.
Plastic in our lives everywhere, plastic products are made of different materials, materials and applications are different. The figures at the bottom of the plastic bottle represent different materials.
The number "1" represents polyethylene terephthalate glycol fat, or pet. Mainly used in mineral water bottles, carbonic acid, juice beverage bottles and soy sauce vinegar bottles. Pet bottle heat-resistant temperature of 70 degrees Celsius, only suitable for warm drink or cold drink, bottled water or heating is easy to deformation, harmful substances to the human body will be dissolved.
The number "2" represents high-density polyethylene, or HDPE. HDPE and other plastics made of composite film, but also for aquatic products.
The number "3" represents polyvinyl chloride, or PVC, which is also used to manufacture intravenous infusion bags and disposable sterile infusion devices because of its low price. However, long-term use can lead to DEHP accumulation of hazardous substances. Therefore, from the safety point of view, the pharmaceutical industry to choose non-PVC materials is the future trend.
The number "4" is low-density polyethylene, or LDPE. Number 4th plastic is used for packing. LDPE is mainly used to produce fresh-keeping film and plastic bags for food.
The number "5" is polypropylene, i.e. pp. One is to make a container. PP is the only plastic container that can be placed in a microwave oven, and is a reusable plastic container that can be used as a storage container for food, oil and condiments. The second is to wrap the film, with both tensile and biaxial stretching. Not stretched polypropylene (CPP) is often used for snacks, bread, fruit and other packaging; biaxial tensile polypropylene (BOPP) is a soft packaging material comparable to cellophane.
The number "6" is polystyrene, i.e. PS. PS is mainly processed into thin film and foamed plastics in packaging. The film is used for the packaging of fruits and vegetables, and foam plastic is used for bowls of instant noodles and snack boxes, but not for high temperature, so it can not be heated directly in the microwave oven, so as to avoid the release of toxic chemicals due to high temperature.
The number "7" is polycarbonate, i.e. PC or other plastic. PC material made of plastic containers, may release toxic bisphenol A, the higher the temperature released more, the faster, so do not heat when used, also do not direct in the sun.
Plastic products generally include plastic ingredients, molding, machining, bonding, modification and assembly. After four of the process is plastic has been molded into products or half of the product, also known as plastic two times processing.
The key link of forming plastic processing in plastic products production. A product or billet of various shapes (powder, grain, solution or dispersion) is made into the desired form. The molding method is up to more than 30 kinds. Its choice depends mainly on the type of plastic (thermoplastic or thermosetting), the starting form and the shape and size of the product. Plastic processing thermoplastic plastics commonly used methods are extrusion, injection molding, calendering, blow molding and thermoforming, plastic processing thermosetting plastic generally used molding, transfer molding, but also with injection moulding. Laminating, moulding and thermoforming are made to form plastic on a plane. The plastic processing method can be used in rubber processing. In addition, there are liquid monomer or polymer as the raw material casting and so on. In these methods, extrusion and injection molding are used most, and also the most basic molding method.
Mechanical processing of plastic products using plastic processing methods such as metals and wood, manufacture of a very precise or a large number of plastic products, can also be used as a molding auxiliary process, such as the cutting of extruded profiles. Because of the plastic performance and metal and wood, the thermal conductivity of plastic poor, thermal expansion coefficient, low modulus of elasticity, when the clamp or tool pressure is too large, easy to cause deformation, cutting when the heat is easy to melt, and easy to adhere to the tool. Therefore, the plastic machine processing, the tool used and the corresponding cutting speed must be adapted to plastic characteristics. Commonly used mechanical processing methods are sawing, shearing, punching, car, planing, drilling, grinding, polishing, thread processing. In addition, the plastic can also be used for laser truncation, drilling and welding.
Jointing Plastics for the manufacture of plastic products The method of jointing plastic parts is welding and bonding. Welding method is the use of hot-air welding electrodes, hot-melt welding, as well as high-frequency welding, friction welding, induction welding, ultrasonic welding and so on. The bonding method can be divided into flux, resin solution and hot melt adhesive according to the adhesive used.
The surface modification of plastic products is to beautify the surface of plastic products, usually including: mechanical modification, that is, the use of file, grinding, polishing and other processes, remove the workpiece on the burrs, burrs, and modify the size, etc., including coating the surface of the workpiece, with a solvent to make the surface bright, with patterned film coated products surface, etc. Shiya, including painting, Printing and stamping, gold-plated genera, including vacuum coating, electroplating and electroless silver plating. Plastic processing hot stamping is in the heat, pressure, will be hot stamping film on the color of aluminum foil (or other decorative film layer) transferred to the workpiece. Many household appliances and construction products, daily necessities, such as the use of this method to obtain metal luster or wood pattern and other patterns.
The Assembly of plastic products is bonded, welded, and mechanically connected, so that the plastic parts made are assembled into complete products. For example: Plastic profiles, through sawing, welding, drilling and other steps assembled into plastic window frames and plastic doors.