Foam molding
DATE：2022/1/20 8:44:58 / READ： / SOURCE：This station
foam molding
The pouring molding of foam plastic is similar but not identical to that of metal. The pouring molding of foam plastic is mainly used for foam molding of thermosetting plastics. In the pouring process, it is mainly used for the foaming molding of thermoplastics. In the process, the race reaction process and the foaming molding and setting process are carried out at the same time. Therefore, each component of the raw material must be fully carried out before casting. In the mixing process, the body and the mold only exert a small pressure or are in a free state when pouring the body, the strength requirements for the mold and other forming equipment are low, and the investment is less; there are less restrictions on the size of the product, and the product should be In the production of large-scale products, it can also be constructed on site, which is more convenient. The disadvantage is that the dimensional accuracy of the finished product is poor.Foam casting is mainly used in polyurethane foam, urea formaldehyde foam, other such as phenolic foam, polyvinyl formal foam, epoxy foam, silicone foam, water-containing polyester low-foaming plastic, etc. are also available Pouring method for foam molding. But it is mainly the first three that form the industrialized production, especially the polyurethane foam is widely used and develops rapidly. This chapter will introduce it as the leading.
Polyurethane foams vary according to the raw materials used. It can be divided into polyester polyurethane foam and polyether polyurethane foam. According to the soft and hard properties of the texture, it can be divided into rigid polyurethane foam, semi-rigid polyurethane foam and flexible polyurethane foam. According to the raw procedure, it can be divided into one-step method and two-step method. According to the shape of the product, it can be divided into three categories: block product, product and spray. Since foam casting molding generally undergoes strong fusion, mechanical stirring foam molding is also classified into this category.
Ammonia foamed plastic has good performance, small bulk density, high strength, low thermal conductivity, pumping,,, shock resistance, shock load absorption, sound insulation, etc. , Seat cushions, bedding materials, packaging materials, filter materials, life-absorbing, sound-absorbing, shock-proof materials, daily necessities and carpet pads. Rigid and semi-rigid polyurethane foams are mostly used in industry and business, such as sandwich materials for radomes. sound-absorbing material. Insulation materials for chemical equipment and instruments, insulation materials for refrigeration and oil transportation systems, and packaging materials for various electrical instruments. Since the oil crisis in 1973, foreign countries have attached great importance to energy conservation. Since the thermal performance of hard ammonia is the best, governments of various countries have formulated regulations to encourage enterprises to use hard polyurethane to re-foam plastics. The cast-molded urea-formaldehyde foam is a white block with a closed-cell structure. Its biggest advantages are light weight, low thermal conductivity, and low price, and can be used in industry and agriculture. However, urea-formaldehyde foam has strong water absorption and low mechanical properties, so it is not a straight knot material. The application of polyvinyl formal foam is also expanding day by day. It is not only widely used as a household floor mop material but also can be used in various products that require high water absorption, especially in medical products, because it has high hygienic and safety conditions, Therefore, it has been reused as a replacement material for human organs. The following is an introduction by plastic varieties, dominated by polyurethane foam.
Author：admin