Starch-based plastic
Starch-based plastics use chemical reactions to chemically modify starch, reduce the hydroxyl groups of starch, and change its original structure, thereby changing the corresponding properties of starch and turning original starch into thermoplastic starch.
Chinese name starch-based plastic
table of Contents
1 R & D background
2 Process principle
3 Development status
4 Product advantages
5 Certification system
6 Application prospects
R & D background
Starch is a natural polymer with the second largest output on the earth after cellulose. It is rich in source, renewable and low in price. It can be used to produce starch-based plastics through modified plasticization. As an important category in bio-based materials, starch-based plastics have successfully achieved industrial production and application. Starch-based plastic is a kind of plastic product made by starch as the main raw material, modified and plasticized and then blended with other polymers, which belongs to the category of bioplastics. Starch-based bioplastics can be divided into two categories: bio-based plastics and biodegradable plastics.
Starch-based biodegradable plastic is generally a blend of modified starch and biodegradable polyester (such as PLA / PBAT / PBS / PHA / PPC, etc.), it can be completely biodegradable, compostable, no pollution to the environment, suitable for waste Compost, landfill and other treatment methods. Starch-based bio-based plastics are generally a mixture of modified starch and polyolefins (such as PP / PE / PS, etc.). Its environmental protection significance is to reduce the use of petrochemical resources and reduce carbon dioxide emissions. The waste is suitable for incineration. Both of these materials can replace traditional petroleum-based plastics and are widely used in plastic packaging materials, shockproof materials, plastic films and plastic bags, disposable tableware, food containers, toys, etc.
Process principle
Starch is a natural polymer with a large number of hydroxyl groups in its molecule (molecular structure is Ⅱ and Ⅲ), so the interaction between starch macromolecules is very strong, which makes the original starch difficult to melt process, and it is Compatibility with other polymers during mixing is also poor. But these hydroxyl groups can
Enough to chemical reactions such as esterification, etherification, grafting, cross-linking. These chemical reactions are used to chemically modify the starch, reduce the hydroxyl groups of the starch, and change its original structure, thereby changing the corresponding properties of the starch and turning the original starch into a thermoplastic starch.
1. Esterification, transesterification or etherification
In order to change the hydrophilicity of starch to hydrophobicity, the hydroxyl groups on the starch molecule are esterified and transesterified with fatty acids, fatty acid esters, etc. to produce starch esters.
2. Crosslinking reaction
In order to improve the strength and heat resistance of starch materials, the starch is subjected to a cross-linking reaction with compounds having two or more functional groups (such as polyacids, etc.), so that the starch is moderately cross-linked.
3. Blending, reforming, and copolymerizing independent innovation
Most starch plastics are prepared by blending starch with other polymer materials. The resulting product has poor strength due to poor compatibility and limited use. Starch-based plastics also undergo starch copolymerization in the starch modification process to obtain graft copolymers of starch and other polymers, thereby improving the compatibility of starch with other polymer materials. Through chemical modification, three modifications of starch were achieved: hydrophilicity was changed to hydrophobicity; heat sensitivity was changed to temperature resistance; hard and brittleness was changed to plasticity. This modification solves the worldwide problem of starch modification and lays a good foundation for subsequent processing.
process status
Starch-based bioplastics have a 30-year history of research and development. It is a biodegradable plastic with the longest R & D history, the most mature technology, the largest industrial scale, and the highest market share. In the early 1980s, research and development of modified starch and degradable plastic alloy masterbatches that were completely biodegradable or soluble plastics, the blending of starch and biodegradable resins received attention. Among them, the most successful is the "MaterBi" of Novamont, Italy. It is a polymer plastic alloy with interpenetrating network structure composed of a blend of modified starch and modified polyvinyl alcohol. It has good processability, secondary processability, and mechanics. Performance and excellent biodegradability. In addition, "Vinex" developed by American Air Product & Chemical Company is a polyvinyl alcohol-based resin with a low degree of polymerization. It also has water solubility, thermoplastic processability and biodegradability, and has received great attention in recent years.
In recent years, countries have generally shifted their research focus to plastics with as much starch content as possible, and developed some completely degradable materials with excellent properties, and even obtained pure starch products without synthetic polymers, namely thermoplastic starch. The "Novon" biodegradable material produced by Warner-Lambert of the United States has a starch content of more than 90%; the Japanese Corn Company and the Michigan Institute of Production Technology jointly developed a high starch content material, which has the advantages of strong water resistance In addition, Sumitomo Corporation of Japan and Ferrizz Corporation of Italy also announced that they have successfully studied all-starch plastic with a starch content of 90%. In terms of making starch into thermoplastic starch for the production of biodegradable plastics, research institutes such as the German Batekke Institute, the American Warner-Lambert Company and the Swiss University have made great progress. The National Food Processing and Packaging Science Center of Australia has launched an all-starch thermoplastic with good fluidity, ductility, and mold release. The product is soft, transparent, high-strength, and has a controllable degradation rate. Packaging film and other products.
China's starch plastics were first developed by the Institute of Applied Chemistry of Jiangxi Academy of Sciences in the late 1980s. According to incomplete statistics, there are now more than 60 universities, research institutes and enterprises participating in the research. China is gradually narrowing the gap with foreign developed countries in the research and development of starch-based plastics. At present, the main domestic starch-based materials and products manufacturers and status are as follows: Wuhan Huali 40,000 tons / year, is planning to build a production line with an annual output of 60,000 tons; Shenzhen Hongcai 15,000 tons / year; Suzhou Hanfeng 10,000 tons / year; Zhejiang Tianhe is 10,000 tons / year; Zhejiang Huafa is 10,000 tons / year; Shandong Boke is 10,000 tons / year; other production enterprises include Nanjing Biaoge and Changzhou Longjun.
The starch is modified and plasticized by chemical methods. The resulting modified starch has three major characteristics: 1. Hydrophobicity. Starch is completely hydrophobic after chemical modification, and the moisture content is <1%, and it has good compatibility with other synthetic polymer materials. 2. Temperature resistance. Modified starch can withstand a high temperature of 230 ° C without yellowing or decomposition during thermoplastic processing. 3. Thermoplastic. Modified starch can be thermoplastic processed on plastic processing equipment. The company's starch-based plastics are divided into two series: bio-based and bio-degradable. According to different processing techniques, they are divided into blown film materials, injection molding materials, sheet materials, and foam materials. They can be widely used in industrial, pharmaceutical, Packaging of food, electrical appliances and other products and fields such as tableware, kitchenware, toys and flower cultivation. Thereby saving a lot of oil resources, reducing carbon dioxide emissions, and realizing the harmless treatment of garbage, it is also conducive to promoting agricultural development and increasing farmers' income, and promoting the vigorous development of circular economy.
It was reported on July 12, 2018 that Yu Long successfully developed and industrialized all-starch biodegradable materials for the first time in the world. [1]
Product advantages
Compared with traditional plastic products, the advantages of starch-based materials and products are as follows:
⑴ Similar performance: It has the same and similar performance as the traditional plastic products of the same type;
⑵Environmental protection: starch-based bio-based plastics and products have the advantages of saving oil resources and reducing carbon dioxide emissions; starch-based bio-degradable plastics and products have the advantages of complete biodegradation and compostability, and the advantages of harmless treatment of garbage;
⑶ Safety: Starch-based materials and products do not contain toxic and harmful substances such as plasticizers, bisphenol A, and heavy metals. Food-grade materials meet the requirements of relevant standards for food-grade plastics at home and abroad;
⑷ Production process: There is no discharge of three wastes in the production process, which will not cause new pollution to the environment;
⑸ Cost: Starch-based bio-based plastic materials and products are the same as ordinary petroleum plastic products. The cost of starch-based biodegradable materials and products is about twice that of ordinary petroleum plastics.
Certification System
In recent years, the environmental performance of bio-based products has been gradually recognized at home and abroad, which has greatly expanded the application field of bio-based materials. The bio-carbon content of bio-based materials is an important feature different from ordinary plastics. The definition of bio-carbon content is the percentage of bio-carbon in the product to organic carbon (including bio-carbon and fossil carbon). Since bio-carbon is new carbon and does not cause pollution to the environment, it has a good environmental protection effect. The standards for the detection of bio-carbon content include the American ASTM D6866-08: Test method for measuring the bio-content of solid, liquid and gas samples by radiocarbon analysis method and the liquid scintillation counter method for the determination of bio-based content in bio-based materials in China GB / T29649-2013 Since contemporary organisms contain equal amounts of radioactive carbon elements, the principle of ASTM D6866 is to use this characteristic of organisms to measure the biobased content of samples in any state; this measurement method can determine any biobased products and organisms. The exact percentage of bio-based or renewable substances contained in a mixed product.
In 2009, the Belgian authoritative certification agency Vincotte issued the world's first batch of OK Biobased star certification product certification certificates, which carried out an authoritative grade certification on the bio-carbon content of bio-based materials, and also provided a reliable product quality for the bio-based materials market Third-party reviews. OK-Biobased is Belgium's environmental protection label for bio-based low-carbon products. Bio-based plastic manufacturers can affix their labels on the product packaging or products after they are certified to distinguish common petrochemical products. It defines bio-based materials based on the content of bio-carbon, and evaluates the percentage of bio-carbon content and total carbon content. Its standard is ASTM D6866, which classifies the star rating of the materials and is the authoritative bio-based material certification mark of the EU. The OK Biobased logo uses an asterisk to distinguish the environmental protection level of the product. A certified product obtains a 1 star mark to prove that its product contains 20% to 40% biochar, 2 stars to 40% to 60%, 3 stars to 60% to 80%, and 4 stars to more than 80% biocarbon content product. Vincotte's OK Biobased certification aims to help companies or distributors improve the market competitiveness of renewable products and guide consumers to better choose environmentally friendly products.
To encourage the development of bio-based materials and products, the USDA has implemented a bio-priority program. The plan has two procedures, a priority plan for government procurement and a voluntary labeling plan for consumers. The former encouraged the development and establishment of bio-based products in 2002, while the latter was released in 2008. The purpose of the BioPriority Program is to incentivize the consumption of biomass products in the United States. Federal government agencies and their contractors give priority to purchasing products with the highest biomass content. If the product meets the minimum standards for the biobased content of the USDA biobased product list, any factory or distributor can participate in this program, and the certification mark issued by the agency can be affixed to the product packaging.
The international certification of biodegradable plastics includes OK Compost certification in Belgium, Compostable certification in Germany, and BPI certification in the United States.
OK Compost is a compostable certification named "OK Compost" issued by the Belgian certification body AIB-Vincotte Group after being tested according to the detection standard EN13432 or ASTM D6400 for biodegradable materials. The purpose of OK Compost certification is to help companies or distributors improve the market competitiveness of fully degradable products and guide consumers to better choose environmentally friendly products.
Compostable certification is a certification of biodegradable products launched by DIN CERTCO, a joint certification body of TUV Rheinland Group and Deutsches Institut fr Normun (DIN). The certification mark is the "seeding" mark. Compostable certification can help buyers select products from many suppliers and manufacturers that strictly control the quality, safety and environmental protection. At the same time, products with the Compostable logo indicate that they have successfully passed the test and evaluation by an authoritative third-party organization, which helps to enhance customers' purchasing confidence and effectively promote product sales. In addition, the relevant information of the certificate holder can be queried on the official website of DIN CERTCO to prevent misuse or forgery of the logo.
BPI is an abbreviation of Biodegradable ProductsInsitute. BPI educates producers, legislators and consumers on the scientific standards of degradable materials through innovative compostable labeling schemes. At the same time, through a series of procedures to ensure that related products meet the requirements of degradable materials standards.
The first batch of Chinese enterprises in Wuhan Huali Environmental Protection that obtained OK Biobased certification have already obtained four-star bio-based product certification. At the same time, the company's biodegradable materials obtained OK Compost certification and Compostable certification.
Application prospect
With the gradual shift of consumers' preference for plastic products, renewable environmentally friendly materials are gaining popularity in the market. Affected by this, the market demand for bio-based plastics has increased. As governments of all countries attach importance to bioplastics, the total value of global bioplastics demand is expected to increase to US $ 5.9 billion in 2020, equivalent to an average annual growth rate of 20%.
Recently, the French Parliament passed laws on energy transition and green growth. In addition to reducing the proportion of nuclear energy in the French energy structure, the new law also contains legislative proposals related to renewable energy and plastic packaging. For example, renewable energy will grow by 40% by 2030 and carbon dioxide emissions will be reduced by 40% by 2030; lightweight packaging bags used to package fruits and vegetables will have to be made of bio-based materials starting January 1, 2017; In addition, the plastic packaging used for commercial mail will also be implemented to the same standards at the same time. The latest legislation of the French government requires that disposable tableware such as dishes, cups and forks must be made from bio-based materials instead of petroleum-based materials.
RnR Market Research consulting company market analysts have recently predicted that the global demand for bio-based plastics will increase at an annual growth rate of 19% in the next four years, and its market demand will reach 950,000 tons in 2017. Europe is the world's largest consumer market for bio-based plastics. In 2012, the use of bio-based plastics in the region accounted for more than half of the global total. The survey report shows that consumers in European countries are more inclined to choose new bio-based plastic products than traditional plastics. Therefore, the region is expected to continue to lead the list of bio-based plastic consumption. In terms of types, starch-based plastics and polylactic acid will remain the most demanded bio-based plastics in the next few years, and their market consumption will account for more than 60% of the total. RnR Market Research said that in recent years countries have issued plastic restrictions in order to continuously increase the supervision of the use of traditional plastics, which is conducive to further pushing up the demand trend of bio-based, especially starch-based plastics.
In 2013, the State Council issued the "Bio-Industry Development Plan" (hereinafter referred to as "Plan"). The "Plan" pointed out that bio-based materials will be accelerated
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