Contact: Zhao Fanzhang
Contact: Xiong Jingyu
Official website: www.gdsdzz.com
Address: No. 6, Yongxing Street, Leliu, Shunde District, Foshan City, Guangdong Province
Rotational molding is a branch of plastic processing. Compared with other plastics processing, it has the advantages of less equipment investment, lower mold cost, flexible product design, and integrated molding. In recent years, in the developed countries of North America and Europe, the rotational molding industry has developed rapidly, and its development speed is higher than the average development speed of the whole plastic industry. The development of the whole rotational molding industry is also relatively perfect. In addition to the rotational molding machine manufacturing plant and the rotational molding product factory, there are a considerable number of other professional auxiliary factories, such as the rotational molding mold factory, the release agent production plant, the rotational molding special pigment production plant, the milling machine manufacturing plant, the insert manufacturing plant and the mixing equipment manufacturing plant suitable for the rotational molding, as well as a large number of rotational molding special raw materials supply Factory and so on. The rotational molding equipment made in developed countries is more and more sophisticated, and is developing towards the direction of higher and higher level of automation control.
1. Development of rotational molding technology in Foshan
1.1 the rotational molding equipment tends to be automatic
One of the important factors to promote the development of roll molding industry is the automation and high performance of rotational molding equipment, which can improve the molding efficiency, reduce the production cost, shorten the molding time, increase the output and further improve the degree of freedom of product design. Industry insiders believe that to achieve this goal, the first is to develop new polymers, additives and colorants, so that they can be directly fed into the rotational molding mold at any position, making it possible to form multi-layer rotational plastic parts and high-performance fiber reinforced plastic roll molding, and automatically control the cooling in the mold; the second is to shorten the adding and following cycle through the automatic feeding, heating, cooling, demoulding and other processes And reduce the internal stress of polymer, improve the size and stability of products, open the door of high added value plastic roll forming application.
At present, to improve the automation of production has become the goal of rotational molding manufacturers, which promotes the development of rotational molding production equipment to the direction of automation. Italy's persico S.p.A. promotes a fully automated rotational molding production line Leonardo in Europe, North America and Australia. The production line can complete the operations of feeding, mold opening and taking out products by itself. The products that can be produced include water tank, fire extinguisher box, rowing boat, toys, roof and tray, etc.
Italian plastic rubber industry has decades of rich experience in rotational molding technology. The most important feature of the shuttle rotary molding machine group, an Italian manufacturer, is the efficiency improvement brought about by its flexibility. Persico S.p.A. has introduced the fully automatic electric heating rotational molding technology to meet the requirements of high-performance rotational molding of different materials.
Foshan roll molding
1.2 rotational foaming technology
At present, more and more PE materials are used to replace polyurethane foam in rotational molding, and the rotational products are more ideal in terms of strength and weight. Shinny Case, Japan, invented a new technology, that is, the use of polyethylene foam in the WIP and the use of polyethylene or polypropylene in the outer layer. Unlike previous rotational molding foams, foam is not formed by blowing agents but through a pre expanded parent material with a special structure. Through one-step process, the pre foaming masterbatch and the particles forming outer crust are added into the mold at the same time, and the adding temperature is controlled at 3000 ℃. Thus, the shells of the pre foaming masterbatch can be connected to form a network structure, which plays a role of strengthening support. At the same time, the density of the inner foam is very small, and the pressure inside the mold can reach 2kg/cm3, so we need to pay special attention to the problem of exhaust. There are two brands of this material, one has a foaming ratio of 6-40 times, and the other has a foaming ratio of 5-13 times. In addition, the formulation of the base material has also been carefully designed because the rheological behavior of the conventional rotational resin does not meet the requirements of the process. This material can be used in refrigerators, floating facilities, hot water tanks, chemical solvent tanks and sports equipment.
1.3 cross linked polyethylene for rotational molding
Crosslinking makes the linear polyethylene molecular chain connected into a network, which greatly improves the toughness, rigidity, long-term service temperature and environmental stress cracking resistance of polyethylene molecules, and has excellent impact resistance, thus expanding the application range of PE material, which can be used in the manufacture of chemical solvent storage tank, solar water heater, electric water heater, heat pump air conditioner, water heater water tank, chemical industry, etc Lower pipeline and next vehicle fuel tank, etc.
Generally, ethylene crosslinking can be divided into two categories: peroxide crosslinking and silane grafting hydrolysis condensation crosslinking. The crosslinking structure of the former is planar structure, and the latter is somatotype structure. The advantage of peroxide crosslinking is that the crosslinking reaction can be completed in the molding process, while silane grafting hydrolysis crosslinking must be completed in boiling water bath or steam bath, and condensation catalyst must be involved. Another feature of this method is that it has adhesion to the metal wall, which can be used to produce many steel plastic composite pipe fittings and hollow tank containers. The two technical routes can be used for rotational molding.
1.4 new resins
At present, synthetic resin manufacturers are also constantly improving the molecular design, catalyst formula and production process. Lyondell Base11 Co., Ltd. has launched two high-performance rotational grade HDPE resins gx5002 and gx5003. Both resins are produced by spheriline s low-pressure gas-phase technology and unique catalyst system. They have superior low-temperature impact resistance, environmental stress cracking resistance, and good creep resistance, which can meet the requirements of transportation and outdoor use in cold and hot weather. Generally, melt fluidity is negatively correlated with impact strength