Rotational molding products originated in the United Kingdom in 1934. Since the 1940s, Europe has used polyvinyl chloride paste to produce toys such as plastic balls through rotational molding methods. In the 1950s, a polyethylene rotomolding process using low-density polyethylene powdered resin as a raw material was developed to produce polyethylene storage tanks, large pipes and other industrial products, which greatly promoted the development of rotomolding processes.
In the 1960s, due to the continuous improvement of resin properties and rotomolding equipment, the rotomolding process developed rapidly. Many special plastics for rotational molding have been developed abroad. RaychemsF1amo1in711 is a cross-linked polyethylene resin for rotomolding. In addition to cross-linking, it also has self-extinguishing properties. Philip's famous rotomolding grade cross-linked polyethylene resin MarlexCl-100 was also developed during this period.
In order to meet the needs of preparing large-scale rotomolding products, in the late 1960s, many machines and equipment that can effectively use the floor space and heat energy to rotomold large-scale plastic parts were developed. By 1970, more than half of the rotomolding machines on the market had a rotating diameter range of more than 1.75m. In addition, the control level of the machine has also been improved to varying degrees. For example, the three-arm rotational molding machine McNeilAuronismodel3000-200 can control the heating and cooling cycles of each arm separately, so as to simultaneously rotationally mold products of different sizes and different materials, and its rotation The diameter is up to 5m, and the total weight of the mold and resin that each arm can bear is about 13,500N; the jacket rotomolding machine with good heat transfer effect and small footprint was also designed and manufactured during this time.
In the early 1970s, there were more than 50 companies engaged in the production of rotomolding products in the UK, and more than 70 manufacturers of rotomolding thermoplastics; in continental Europe, there were more than 20 companies engaged in rotomolding processing, including Germany, France, Companies from Italy, Switzerland, Norway, Austria, Denmark and other countries.
In the early 1970s, there were more than 500 companies in the United States engaged in the production of rotomolding products, with more than 500 rotomolding machines, and the capacity of rotomolding containers exceeded 10,000L (2400 gallons); the plastics that the rotomolding machines can produce The product size is 4.6×4.6×2.1m. Rotomolding has experienced three major developments in the 1950s, 1970s, late 1980s and early 1990s. It has been quite developed in Western Europe and North America. It has formed a company specialized in the production and preparation of rotomolding materials, and rotomolding machinery and equipment. An independent industrial system composed of professional company manufacturing and sales, professional scientific research and education of rotational molding technology, and numerous factories of rotational molding products.