The hottest polypropylene foamed plastics are wide

2022-08-18
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Polypropylene foamed plastics are widely used

polypropylene (PP) resin has the characteristics of rich source of raw materials, light weight, excellent performance/price ratio, excellent heat resistance, chemical corrosion resistance, easy recycling and so on. It is one of the resins with the widest application and the fastest output growth in the world. The main varieties of PD foams include polyurethane (PU), polystyrene (PS) and polyolefin foams. There are isocyanate residues harmful to human body in the foaming process of PU foaming materials, and the foaming materials cannot be recycled; PS foaming products cause "white pollution" to the surrounding environment because they are not rotten and difficult to recycle. The United Nations environmental protection organization has decided to stop the production and use of foamed PS worldwide in 2005. Foamed PP products have attracted much attention because of their good thermal stability (up to 130 ℃) and dimensional stability under high temperature, high toughness, tensile strength and impact strength, suitable and flexible surface, excellent microwave adaptability, degradability and environmental protection, and have become a good substitute for PS

at present, some developed countries in the United States, Japan and Germany are vigorously developing it as a green packaging material to replace foamed PS. The University of Wisconsin successfully developed a new type of elastic polypropylene foam at the end of last year. It not only has many advantages of expanded polystyrene, but also solves some shortcomings of polystyrene. The plastic manufacturers of this kind of elastic polypropylene foaming plastic know that the plastic is mainly composed of resin. The production method is to first add metal catalyst during the polymerization of propylene molecules, so that the polypropylene molecules produced alternate between hard and elastic types to form block polymers, and then add special foaming agent for foaming, so as to obtain elastic polypropylene foaming plastic. Its hard molecular chain makes the material have certain strength and stability, while the elastic molecular chain gives the material tough and flexible properties

the development of packaging materials and processing, as well as the new packaging design, have the trend of "lightweight" in China's waste plastic modified plastic material receiving industry, and foamed plastic is more conducive to the lightweight of plastic packaging. Now microwave ovens and microwave foods have entered people's family life, and the heat resistance of food packaging containers hot formed with cross-linked foamed PP sheets is as high as 130 ℃ (while foamed PS is only 80 ℃), which is also moving forward from the original single-1 tension and compression experiment to a variety of experimental characteristic tests. It can be used in microwave ovens, and it is resistant to boiling water, has good high-temperature stability, and the surface feels comfortable and soft; Its thermoformed plates and bowls are superior to PE and PS in low temperature performance, so it has obvious advantages for one-time packaging. According to incomplete statistics, China currently consumes about 18billion disposable tableware every year. As a substitute for foamed PS, paper tableware will bring greater environmental harm due to the consumption of a large amount of wood. PP is easy to degrade under the action of light, heat and oxygen; In the manufacturing process of PP products, if antioxidants and other additives are not added, PP products will age, degrade and crumble into powder particles in about 15 days under the sun. Using the inherent characteristics of PP, disposable tableware made of foamed PP sheet is an ideal environmental tableware

at present, supermarkets are expected to need 10billion trays for various fruits, cooked food, semi-finished products, clean vegetables, etc. If half of these disposable tableware and trays are replaced by cross-linked PP foaming materials, more than 150000 tons of PP foaming sheets are required. In addition, PP foam sheet can also be used as personal packaging for computers, cameras, glassware, precision parts, vulnerable parts and other items. Because it can be recycled directly, its texture is soft and will not damage the surface of the package, PP foaming material can replace PS foaming material in the field of electrical packaging

reprinted from: plastic machine

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