1) Start with raw materials:
As we all know, the main components of stone paper are thermoplastic resin and calcium carbonate fine powder. The choice of the two materials is closely related to the density and specific gravity of stone paper.
Calcium carbonate, accounting for about 70-80%, is divided into light calcium carbonate and heavy calcium carbonate. The true density of light calcium is 2.4～2.6g/cm3, the true density of heavy calcium is 2.6～2.9g/cm3, and light calcium is passed It is made by chemical methods, and heavy calcium is mainly obtained by mechanical crushing, grinding and sorting. It can be seen that choosing light calcium carbonate is more conducive to the reduction of density, but light calcium carbonate requires more processing procedures. The cost is higher than that of heavy calcium.
Thermoplastic resin, accounting for about 20-30%, mainly polyethylene and polypropylene. Polyethylene is divided into low-density polyethylene (LDPE), which has a low density (0.910~0.925), light weight, flexibility, and low temperature resistance. Good impact. High-density polyethylene (HDPE) has high density (0.941~0.965), has a higher temperature, hardness, mechanical strength and chemical resistance. Choosing low-density polyethylene is more conducive to density reduction .
2) Start with the production process:
The production process of stone paper includes calendering method, casting method, blown film method and biaxial stretching method. The biaxial stretching method is currently unable to be produced in China, and only a few countries can produce it, which can greatly reduce the cost of stone paper. Density, but the equipment is expensive, usually more than 100 million yuan, but the quality of the product is good.
3) Start with foaming:
Foaming is a very common technology in the plastics industry. At present, the market is mainly based on chemical foaming. Chemical foaming is an industry problem in the extrusion process, especially when it is applied to such thin film products.
The other is Expancel microsphere physical foaming technology. This material greatly increases the possibility of film foaming. Expancel microspheres are hollow plastic microspheres that can physically expand and become larger when heated. At a suitable processing temperature, the spheres It will expand and become larger, and it can maintain a closed-cell hollow structure at a heat-resistant temperature.The particle size is 80-120 microns, and films over 150 microns may be foamed.
