Biodegradable plastic refers to a type of plastic that is degraded by microorganisms that exist in nature, such as bacteria, molds (fungi) and algae. The ideal biodegradable plastic is a kind of polymer material with excellent usability, can be completely decomposed by environmental microorganisms after being discarded, and finally inorganicized to become a component of the carbon cycle in nature.
From the classification of raw materials, there are at least the following types of biodegradable plastics:
1) Polycaprolactone (PCL):
This material has good biodegradability and its melting point is 62°C. The microorganisms that decompose it are widely distributed under optimistic or anaerobic conditions. As a biodegradable material, it can be mixed with starch and cellulose materials, or polymerized with lactic acid.
2) Polybutylene succinate (PBS) and its copolymers:
PBS (melting point: 114°C) is the basic material to manufacture various high-molecular-weight polyesters. The technology has reached the level of industrial production. Japan’s Mitsubishi Chemical Corporation and Showa Polymer Corporation have begun industrial production with a scale of more than 1,000 tons.
The Institute of Physics and Chemistry of the Chinese Academy of Sciences is also conducting research on the synthesis of polysuccinate succinate copolyester. The Institute of Physics and Chemistry of the Chinese Academy of Sciences has cooperated with Shandong Huiying Company to build a production line with an annual output of 25,000 tons of PBS and its polymers, and Guangdong Jinfa Company has built a production line with an annual output of 1,000 tons. Tsinghua University has built a production line with an annual output of 10,000 tons of PBS and its copolymers in Anqing Hexing Chemical Co., Ltd.
3) Polylactic acid (PLA):
Natureworks of the United States has done active and effective work in improving the production process of polylactic acid. It has developed the fermentation of glucose in corn to produce polylactic acid, with an annual production capacity of 14,000 tons. Japan’s UNITIKA company has developed and produced many products, among which canvas, trays, tableware, etc. are widely used in the Aichi World Expo in Japan.
China’s industrialization is Zhejiang Haisheng Biodegradable Plastics Co., Ltd. (with a production line of 5,000 thousand tons/year), and the pilot units include Shanghai Tongjieliang Biomaterials Co., Ltd. and Jiangsu Jiuding Group.
4) Polyhydroxyalkanoate (PHA):
The countries that realize industrialized production abroad are mainly the United States and Brazil. Domestic production units include Tianjin Guoyun Biomaterials Co., Ltd. (scale 10,000 tons/year), Ningbo Tianan Biomaterials Co., Ltd. (scale 2,000 tons/year), and Jiangsu Nantian Group Co., Ltd. is undergoing pilot trials. Wait
Using biodegradable plastics obtained from renewable resources, mixing aliphatic polyester and starch together, the technology to produce degradable plastics has also been successfully studied. In European and American countries, blends of starch and aliphatic polyester are widely used to produce garbage bags and other products. The largest and best-selling company in the world is the Italian company Novamont, whose trade name is Mater-bi, and the company’s products are widely used in Europe and the United States.
There are many domestic research and production units. Among them, the production units include Wuhan Huali Technology Co., Ltd. (with a scale of 40,000 tons/year), Zhejiang Huashengtai Technology Co., Ltd. (8,000 tons/year), and Zhejiang Tianhe Ecological Technology Co., Ltd. ( 5,000 tons/year), Fujian Best Biomaterials Co., Ltd. (scale 2,000 tons/year). Zhaoqing Huafang Degradable Plastic Co., Ltd. (scale 5,000 tons/year), etc.
Fatty aliphatic aromatic copolyester:
(5) Aliphatic aromatic copolyester:
The aliphatic aromatic random copolyester (Ecoflex) manufactured by BASF in Germany has monomers: adipic acid, terephthalic acid, and 1,4-butanediol. The production capacity is 140,000 tons/year. At the same time, it has developed biodegradable plastic products based on polyester and starch.
(6) Polyvinyl alcohol (PVA) biodegradable plastics:
For example, the MaterBi product of Italy NOVMANT mainly added PVA to starch in the 1990s, which can blow film and process other products. Polyvinyl alcohol materials need to be modified to have good biodegradability. The Light Industry Plastics Processing and Application Research Institute of Beijing Technology and Business University has achieved certain results in this regard.
(7) Carbon dioxide copolymer:
Abroad, the earliest countries to study carbon dioxide copolymers were mainly Japan and the United States, but there has been no industrial production. Inner Mongolia Mengxi Group Corporation adopts the technology of Changchun Institute of Applied Chemistry and has built a device with an annual output of 3,000 tons of carbon dioxide / epoxy compound copolymer resin. The products are mainly used in packaging and medical materials. The low-molecular-weight carbon dioxide copolymer technology developed by Dr. Chen Liban from the Guangzhou Institute of Chemistry, Chinese Academy of Sciences, has been put into production in Taixing, Jiangsu. The product is low-molecular-weight carbon dioxide/epoxy compound copolymers, which are used as raw materials for polyurethane foam materials and used in household appliances. And other packaging. Henan Tianguan Group adopts the technology of Professor Meng Yuezhong of Sun Yat-sen University and has built a pilot scale carbon dioxide copolymer production line, which is expected to be pilot-scaled this year.
(8) Poly-β-hydroxybutyrate (PHB):
From a global perspective, PHB and PHBV are recognized as one of the most promising biodegradable plastics, and they are also new products under development. The pilot production cost of the technical side is about RMB 40/kg. After the industrialization is put into production, the cost of the product will be further reduced, and the price advantage is obvious. In particular, the simple production process and simple equipment of the technical side are easy to promote and carry out large-scale production.
PBAT modified resin
PBAT, PLA, starch
Properties: Biological material PBAT modified resin is milky white granular semi-crystalline solid, odorless, tasteless, insoluble in water, soluble in water. Degradable under composting conditions.
PBAT modified resin is an alloy material of PBAT and PLA. It uses PBAT as a substrate and a chemical grafting modification production process to link another bio-based fully degradable resin, PLA, and PBAT. Increase the tensile strength of PBAT. The modified resin is 100% biodegradable, has good biocompatibility and biodegradability, and is absolutely harmless to the human body. The melt blown film processing technology can be used. The finished product is white and semi-permeable. It is widely used in various materials such as supermarket shopping bags, food packaging bags, garbage bags, and agricultural mulch.
China Renju Biodegradable Raw Materials & Products:
1) Degradable raw materials:
Bio-based degradation (wheat straw/grain fiber, straw plastic, straw composite material); petroleum-based degradation (pbat, pbs fully degradable resin)
2) Degradable modified materials:
pbat+ starch pbat+pbs+pla
PBAT is a thermoplastic biodegradable plastic. It is a copolymer of butylene adipate and butylene terephthalate. It has both the characteristics of PBA and PBT. It has both good ductility and elongation at break, as well as Good heat resistance and impact performance; in addition, it also has excellent biodegradability. It is currently very active in the research of biodegradable plastics and one of the best degradable materials for market applications.
Characteristics: PBAT is a semi-crystalline polymer, usually the crystallization temperature is around 110°C, the melting point is around 130°C, and the density is between 1.18g/ml~1.3g/ml. The crystallinity of PBAT is about 30%, and the Shore hardness is above 85. PBAT is a copolymer of aliphatic and aromatic, which combines the excellent degradation performance of aliphatic PBAT molecular chain polyester and the good mechanical properties of aromatic polyester. The processing performance of PBAT is very similar to that of LDPE, and the film can be blown with LDPE processing equipment.
Polylactic acid (PLA) is a new type of bio-based and renewable biodegradable material, made from starch raw materials proposed by renewable plant resources (such as rice, cassava, etc.). Starch raw materials are saccharified to obtain glucose, which is then fermented by glucose and certain strains to produce high-purity lactic acid, and then a certain molecular weight polylactic acid is synthesized by chemical synthesis. It has good biodegradability. After use, it can be completely degraded by microorganisms in nature under specific conditions, and finally carbon dioxide and water are generated without polluting the environment. This is very beneficial to environmental protection and is recognized as an environmentally friendly material.
3. The biodegradable plastic bag production line includes:
- (1) Film blowing machine: This unit is suitable for blowing high-density polyethylene (HDPE), low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) plastic films, widely used in food, clothing, textiles, and daily necessities And other civilian and industrial products packaging. The raw materials can be formulated to produce pearlescent film and degradable film.
- (2) Fully automatic heat-sealing and heat-cutting bag-making machine: This machine is suitable for heat-sealing and cold-cutting bag-making of various materials such as PE, PP, etc. It has automatic counting, photoelectric tracking, color bag and white bag conversion, out of step alarm and shutdown And many other self-check functions.
- (3) Dual-channel heat-sealing and heat-cutting bag-making machine: This machine is suitable for processing cylindrical plastic natural color and color-printed customized vest bags (vest bags). It adopts imported photoelectric eye tracking to make the printing pattern position accurate and accurate. It is equipped with a DC speed-adjusting motor. , Cycloidal needle wheel machine decelerates, has multiple automatic protection functions such as overload, overvoltage, overcurrent, and has an automatic counting device, which can set the number of stacks at will.
After the number of bags in each batch is completed, the material is automatically discharged and automatically reset.
- (4) Cutting machine: used for stamping and forming of vest bags and flat bags. Changing the punching knife can process bags of different specifications.
4. PS: The key to environmentally friendly plastic bags is not the film blowing equipment, but the selection of raw materials and formula design.
Ordinary plastics can be used to add degradable pellets such as starch or calcium carbonate, or use their own special degradable materials to process and produce environmentally friendly plastic bags of 1t kitchen waste. After extrusion and dehydration, the output is 600kg, with a moisture content of 70%, 600* 30%=180kg, the moisture content of the material discharged outside the fermentation bin is 50%, 180/50%=360kg, the outgoing moisture is 600-360=240kg, the machine runs for 20h, 240/20=12kg/h.
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