Stone paper, as the name suggests, is paper made of stone. Of course, this is a popular understanding. In fact, stone paper is made of inorganic powders such as calcium carbonate in limestone as the main raw material, and organic resins such as polyethylene or polypropylene and additives are used as auxiliary materials. A new type of paper produced by special processes such as, extrusion, etc. Generally, the proportion of inorganic powders such as calcium carbonate is 70~80% (the particle size is about 1000 mesh, about 13 microns, and the higher requirements need to be nano-level), and the proportion of organic resin is 15~30%. The calcium carbonate content in this paper is much higher than that of organic resin. Gu is commonly known as stone paper or stone paper.
It can be seen that stone paper is completely different from paper made with cotton, linen, wood and other plant fibers in the traditional sense. Since Cai Lun in the Eastern Han Dynasty invented papermaking, plant fiber paper has dominated the world for thousands of years. Until the 1950s, DuPont and other companies in the United States began to develop paper based on organic resins instead of plant fibers, called synthetic paper. It is called chemical film paper, plastic paper and so on. Japan, out of concerns about insufficient wood sources and reducing organic resin inventories, also increased the development of synthetic paper and took the lead in commercial production in the 1970s. Synthetic paper was also developed in our country in the 1970s. At that time, it was called "calcium plastic paper", but it was not used on a large scale. At the end of the 20th century, Taiwanese enterprises in my country developed stone paper with a calcium carbonate content of 80% and realized commercial production. China has only begun to develop and introduce stone paper production technology in the past ten years.
Modern papermaking technology includes the main steps of pulping, preparation, papermaking, and processing. In contrast, the production of stone paper is completely different and closer to plastic processing. There are four main types of stone paper production processes, namely calendering, casting, biaxial stretching and blown film. The calendering method means that the raw materials are blended and banned, then extruded and pelletized, then formed by a calender, and then cut to obtain the finished product.
The casting method is the same as the previous process of the calendering method, except that the back end is formed by a casting machine, which belongs to unidirectional stretching. The properties of the paper are different in the vertical and horizontal directions. It can be used to produce paper of various thicknesses; the two-way stretching process is the same as the first two It is also basically the same, except that the back end is replaced with a biaxial stretching machine, and the paper produced has the same performance in vertical and horizontal aspects. It is used for pictures or advertisements that require exquisite pictures. The back end of the film blowing rule is blown by a film blowing machine. There are more three-layer co-extrusion blown films.
