Nowadays, polyvinyl chloride (PVC) is a kind of plastic which is often used. It is made of polyvinyl chloride resin, plasticizer and antioxidant. Water-soluble plasticizer, but soluble in oil and ethanol and other solvents, so food packaging, production equipment and a variety of food containers in contact with plastic products in the plasticizer may migrate to the food. In addition to one of the plasticizer can be precipitated into the food on the human body hazards, the PVC plastic products at higher temperatures, will slowly decompose hydrogen chloride gas, this gas harmful to humans. Waste PVC burning will produce a lot of dioxins, hydrogen halide, lead and other harmful substances, the air, soil, water and other environments will cause different degrees of pollution. Therefore, PVC is not suitable as a food packaging container.
PVC film is a special application of vacuum lamination machine in the 110 ℃ high temperature pressure on the surface of the plate, easy to fall off. For example, the German production of PVC film raw materials is a special refining, some material is completely extracted, so PVC is completely non-toxic and tasteless, the human skin or respiratory system without any stimulation, for those who are allergic to wood and paint For example, the use of PVC film packaging furniture or kitchen utensils is very appropriate. Through the use of PVC film as a decorative film, people can use a large number of medium plate, particleboard, plywood and fiberboard, reducing the amount of wood used to reduce the destruction of forests and even the environment. From this point of view, PVC film on the protection of the ecological environment made a great contribution. The quality of PVC is no less than other alternatives, and the cost is cheaper than these materials. It has been found through the study that in many industries, the abandonment of PVC will result in substantial additional costs. The specific data show that the abandonment of the use of PVC will add billions of dollars to the extra cost. For a specific consumer, this would mean a huge expense. In the case of windows with PVC as the surface material, if these windows do not use PVC, but use ordinary wood as the surface, then only the cleaning and maintenance of a will increase the number of amazing costs. In a small town in the UK, people use wooden windows over the past 20 years. Some people have investigated the cleaning and maintenance costs of these windows and compared them with the cleanliness of the PVC windows. The results show that the wooden The cleaning costs of the windows are twice as high as the cleanliness of the PVC windows.
PVC has high chemical stability and good plasticity. In addition to a small number of organic solvents, at room temperature can withstand any concentration of hydrochloric acid, 90% of sulfuric acid, 50 to 60% of nitric acid and 20% of the caustic soda, for the salt is also quite stable. PVC thermal stability and light resistance is poor, more than 140 ℃ can begin to break down and release hydrogen chloride (HCL) gas, resulting in PVC color.
Generally, the performance of soft polyvinyl chloride plastics depends to a large extent on the variety and amount of plasticizers. For example, as a high temperature conditions (such as 100 ℃ above) the use of wire and cable, the heat resistance is mainly related to the use of plasticizer volatile. As a low temperature (such as -40 ℃ below) the use of the film, the cold resistance and the choice of plasticizer chemical structure, viscosity and flow activation energy and so on. At the same time soft PVC plastic products, weather resistance, oil resistance, solvent, migration, electrical insulation, etc. are also closely related with the plasticizer. In addition, the plastic variety and the amount of plastic molding process on the impact of the process is also very obvious. For example, when the amount of plasticizer with poor compatibility is increased, it is difficult to introduce kneading and plasticizing, which is encountered in the molding of blow molding, calendering and extrusion. In order to obtain good processing performance, must be a reasonable combination of plasticizers, and control its use.
As with the rigid PVC plastic, in the soft PVC plastic need to add a certain amount of stabilizer, of course, because the soft polyvinyl chloride plastic added a certain amount of plasticizer, processing fluidity is good, so The requirements for the stability of the system as rigid PVC plastic as strict. In the soft polyvinyl chloride plastic, in order to inhibit the resin and plasticizer in the processing and use of the process, in the air oxidation and ultraviolet aging occurs under the deterioration, often added antioxidant. For soft thin products, but also add UV absorbers. The filler used in the soft polyvinyl chloride plastic, in addition to considering the price, dispersion, thermal stability, weatherability, etc., also takes into account the amount of plasticizer absorption (oil absorption), these for the soft plastic properties The impact is relatively large. In addition soft PVC plastic flame retardant, toxicity and other plasticizers and the variety and the amount of use should also be noted.
Plastic film varieties, large output, production methods varied, is widely used in the national economy and people’s daily lives in various fields. Production of plastic film methods are extrusion blow molding method, T-head extrusion method, two-way stretch method, rolling method and salivation method and other processing technology. Production of plastic film substrate with polyvinyl chloride, polyethylene, polypropylene, polystyrene, polyamide, polyester, polytetrafluoroethylene, polyimide and other resins. The use of plastic film is very wide, in industrial production, can be used for chemical, light industry, textile, electronics, machinery, instrumentation and other dust and moisture packaging. In agricultural production, plastic film, seedling film, greenhouse film is essential agricultural materials, it can make crops in advance sowing, early harvest, yield increased. In daily life, plastic film made of food bags, plastic wrap, tablecloths, raincoats, and so already into the tens of thousands of households. In other areas, such as electrical insulation, chemical anti-corrosion, medical and other industries are also common. Polyvinyl chloride film, for example, production and application, there are more than 10 varieties. Polyvinyl chloride products for packaging mainly for a variety of containers, films and hard films. PVC containers mainly produce mineral water, beverages, cosmetic bottles, also used for refined oil packaging. PVC films can be used to coextrusion with other polymers to produce low-cost laminates, as well as transparent articles with good barrier properties. Polyvinyl chloride film can also be used for stretching or shrink packaging for the packing of mattresses, cloth, toys and industrial goods.
Post time: Aug-22-2017