Plastic packaging sheet is mainly used to produce thermoformed products such as disposable plastic cups, plates, bowls, dishes, boxes, etc. It is widely used in the packaging of food, vegetables, fruits, beverages, dairy products, industrial parts and other fields. With the increasing domestic demand, the use of packaging plastic thermoforming sheets is becoming more and more extensive, and the amount of use is also increasing year by year, and the prospects are promising. With the country's emphasis on environmental protection, the "environmentally-friendly degradation sheet production line" adapted to production has been able to successfully supply various types of "degradation sheet" to the market. The "nano sheet" made of "nanoplastics" has become another focus of attention and has become a new "selling point" for manufacturers. In order to improve the shelf life and shelf life of foods, "sheets with high barrier properties" have become the goal of competitive development by various manufacturers.
2 production methods
The common method for producing plastic packaging sheet is the calendering method, which is mainly used to produce PVC, PVDC and other sheets; the other is the extrusion method, which is used to produce BOPS, EPS, PET, PP, HIPS and other sheets. The sheet mentioned in this article mainly refers to the sheet used for thermoformed packaging products produced by the process of "extruder-T-type head-three-roll calender-winding" process. With the development of the packaging sheet industry, the domestic production of sheet machine has also introduced advanced configurations and new machines. For more than ten years, sheet production and sheet machine manufacturing companies have cooperated with each other and introduced them together, which has also improved the overall development level of the plastic sheet industry. The new sheet processing technology and new raw and auxiliary materials are fully utilized in the configuration of advanced equipment.
3 development trends
The gradual improvement of the domestic level of tablet machine manufacturing has promoted the increase in domestic production of plastic sheet companies and the diversification of sheet varieties, and has also promoted the prosperity of the thermoforming packaging industry. The development of China's sheet machine industry generally has the following trends:
1. A single "separate single screw extruder" is used to configure a "vertical three-roller" sheet production line. It is tending to be saturated. Most domestic thermoforming enterprises have this type of sheet production line. Accumulated funds and technological development have made great contributions. The sheet produced by it can basically meet the production requirements, but the sheet produced by it, especially the HIPS sheet, cannot produce satisfactory gloss, and the grade is low. This sheet machine technology has been quite mature, easy to assemble, easy to purchase parts, simple to configure, simple to operate, cheap, and low maintenance costs, and has become a more popular model. Fierce competition has forced some sheet machine manufacturers to switch to other products. For example, "Beijing Shengan" has focused on "development of aluminum-plastic composite panels"; "Shantou Dacheng" has moved to a more advanced sheet production line. Other manufacturers have switched from tablet machine production to sheet processing, plastic cup manufacturing, plastic blistering and other industries. With this sheet machine, you can process PP, HIPS, PE egg tray sheet, plastic packaging sheet and so on. If the calender roll is replaced with an air knife, a thinner sheet for blister can be produced. However, most of this kind of equipment in China is not equipped with this device at present, which brings a lot of inconvenience to production enterprises, which restricts the development of enterprises in the field of sheet materials and molded products to a certain extent.
2. In the sheet production line with a single extrusion configuration, China's first "electromagnetic dynamic extruder" has been successfully applied in the sheet production line. It has the advantages of energy saving, material saving, uniform plasticization, etc., and can produce a variety of Materials are not expensive. This kind of extruder with "Chinese characteristics" should be vigorously promoted and continuously improved, equipped with advanced follow-up equipment and control systems, and introduced our own advanced production line to the world, so as to get rid of the development state that always follows others. . For example: "Shantou Weida" has launched a number of such sheet production lines to the market, and the market has responded well.
3. The sheet machine configured with a single "exhaust-type two-stage single-screw extruder" is a new sheet production line launched by equipment manufacturers to cooperate with "environmental protection". After many arduous experiments and improvements, "Shantou Dacheng" and "Xi'an Wanjie" successfully produced a biodegradable sheet with a starch content of up to 80%. Many domestic companies have used "Xi'an Wanjie" starch degradation materials in the "Shantou Dacheng" degradation sheet production line to produce environmentally friendly degradation sheets and thermoformed products, and the prospects are promising. This sheet production line can process high-fill PP / PE sheet, light / green dual-degradable sheet, and biological starch-degradable sheet. However, domestic "degradable plastics" are not "fully degradable materials" and contain "plastics" to some extent. In addition, the proliferation of a wide range of "degradable materials", the existence of fish-eye mixing, the competition of "pulp molded products", and the impact of the resurgence of "foamed lunch boxes", the market situation of degradation thermoformed products is not optimistic.
Fourth, in order to reduce costs and grasp the market, enterprises that produce degraded sheets have purchased granulation production lines and used "twin-screw granulation production lines" to supply their own "degraded sheet" production lines. For example, Shanghai Jinying, Xi'an Wanjie, Xi'an Maxcom and other plastic packaging companies have their own "twin-screw granulation production lines." We believe that the production technology of "degradable granules" on the market has matured and the price has dropped to a very low level. Companies that produce "degradable sheets" do not need to launch granulation production lines themselves, because there are already many granulation production lines with insufficient tasks and even equipment. Idle. In addition, some sheet machine manufacturing companies are developing a "twin-screw extrusion degradable sheet production line", with the goal of eliminating the intermediate process of "granulation" and directly producing sheets with the matched powder to further reduce production cost. And this "twin-screw extruded sheet production line" can also process high-fill calcium-plastic degradation sheets and extruded sheets such as PVC and PVDC.
5. K-resin blended transparent KPS sheet has a tendency to replace PP transparent sheet to make disposable containers, and to replace BOPS and PVS to produce sheet. Because BOPS and PVC sheets require special equipment for production, most of the BOPS and PVC sheets required by general thermoforming companies are outsourced. In addition, the PVC scrap material cannot be used by the company itself, and the recycling price is very low, which increases the production cost of the company. Another reason is that PVC recycled materials are susceptible to contamination of other plastics, so extra care must be taken during production, which brings some trouble to the production operation. KPS sheet can be processed on a general extrusion sheet production line, which can be used by scrap companies, and can increase its own sheet production and reduce production costs. Therefore, some companies have started to use KPS sheets to make transparent drinking cups, which have good hardness and toughness. Some also use KPS as lids instead of PVC sheets. KPS sheet is a blend of K-resin and GPPS resin. K-resin is produced by Phillips Chemical Company, and the price is gradually falling. The possibility that it will replace PP sheet, PVC sheet and BOPS sheet will be further increased. Domestic production of PP sheet equipment can also produce more satisfactory KPS sheet.
6. The "multi-layer composite co-extruded sheet" has been favored by the market due to its special properties. The development of the dairy and beverage industries has increased the requirements for plastic cups. In addition to requiring good appearance quality, transparency, lightness, and stiffness, it also requires a long-term preservation function and shelf life, and single-layer sheets cannot meet this requirement.  Manufacturers of sheet materials have launched "multi-layer co-extruded composite sheets", which is not only the market demand, but also the need for product replacement. The single-layer sheet machine has less investment, many competing manufacturers, and low sheet prices. The multilayer composite sheet production line has a large investment, fewer competitors, good sheet quality, high-grade thermoformed products, and good market prices. Another reason is that the production of composite co-extruded plastic sheets can consume more recycled materials and reduce costs.
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