Overview of the development of rotational molding

Overview of the development of foreign rotational molding industry

rotational molding originated in Britain in 1934. Since the 1940s, although 25.9% of bridges in the United States have various problems, Europe has used PVC paste to produce toys such as plastic balls through rotational molding. In the 1950s, the polyethylene rotational molding process with low-density polyethylene powder resin as raw material was developed to produce polyethylene storage tanks, large pipes and other industrial products, which greatly promoted the development of the rotational molding process. Since then, nylon, polycarbonate, ABS and other plastics have also been formed by rotational molding process

in the 1960s, due to the continuous improvement of resin properties and rotational molding equipment, rotational molding technology has developed rapidly. Many special plastics for rotational molding have been developed abroad, such as polyethylene resins such as pep-320 and raychemsflamolin771 developed by United carbonization company. Pep-320 is a kind of low-density polyethylene, which has both good flow forming properties of low-density polyethylene resin and low-temperature impact toughness, chemical resistance and stress cracking resistance of high-density polyethylene resin

raychemsf1amo1in711 is a kind of cross-linked polyethylene resin for rotational molding. In addition to being cross-linked, it also has self extinguishing property. Philips' famous rotational grade cross-linked polyethylene resin marlexcl-100 was also developed during this period

in order to meet the needs of preparing large-scale rotational plastic products, many machines and equipment that can effectively use the floor area and heat energy to carry out rotational molding of large-scale plastic products were developed in the late 1960s. By 1970, more than half of the roll molding machines on the market had a rotation diameter range of more than 1.75m. In addition, the control level of the machine has also been different. The following methods of discrimination and detection are proposed: the degree is improved. For example, the three arm rotational molding machine mcneilauronismodel3000 200 can control the heating and cooling of each arm respectively, with a wide range of molding temperature cycles, so that products of different sizes and materials can be formed by rotational molding at the same time. Its rotation diameter is up to 5m, and the total weight of mold and resin that each arm can bear is about 13500n; The jacketed rotational molding machine with good heat transfer effect and small floor area was also designed and manufactured during this period

in the early 1970s, there were more than 50 companies engaged in the production of rotational molding products in Britain, and there were about 70 manufacturers of Rotational Molding Thermoplastics; In the European continent, there are more than 20 companies engaged in rotational molding processing, including companies from Germany, France, Italy, Switzerland, Norway, Austria, Denmark and other countries. The UK has been able to provide rotational molding machines that can produce containers with a capacity of 18000l; The Netherlands has produced a large cylindrical water storage tank with a diameter of 2.1m and a length of 4.8m. The tank is 540kg and has a wall thickness of 25mm. At that time, the total volume of rolled plastic products in Europe had reached more than 15000 tons, including 7000 tons in Britain alone

in the early 1970s, more than 500 enterprises in the United States were engaged in the production of rotational molding products, with more than 500 rotational molding machines, and the capacity of rotational molding containers has exceeded 10000l (2400 gallons); The largest plastic parts produced by the owned rotational molding machine reach 4.6 4.6 2.1m. Rotational molding has experienced three major developments from the 1950s, 1970s, the late 1980s to the early 1990s. It has been quite developed in Western Europe and North America. It has formed an independent industrial system composed of professional companies for the production and preparation of rotational molding raw materials, professional companies for the manufacture and sales of rotational molding machinery and equipment, professional scientific research and education of rotational molding technology, and a large number of factories for rotational molding products. All thermoplastic resins and some thermosetting resins can be used to produce products as small as table tennis balls and as large as 85m3 in volume, with various shapes, seamless and one-time forming. Rotational molding industry has become a large-scale plastic molding industry. By 1992, the resin used for rotational molding in the world accounted for% of the total consumption of resin in the world. More than 5000 kinds of rotational molding products have been registered with the American rotational molding Association. At present, there are about 1000 enterprises in the world that widely use rotational molding flame-retardant materials in the body. As a major international organization in the rotational molding industry, the international rotational molding Association (ARM), based in the United States, has members in 58 countries, including producers of rotational molding products, raw materials, mold design manufacturers, etc