First, the concept of biological engineering packaging materials
What is a biological material? Because of the richness of biological materials, and the fact that biological materials are researched by scientists from different fields, there is no precise definition of biological materials. The generalized biological material can be understood as all biologically relevant application materials. According to their applications can be divided into bio-engineering materials? Biomedical materials and other biological applications. According to the sources of biomaterials, they can be divided into natural biomaterials and artificial biomaterials; at the same time, the development of materials science has made some materials both natural and synthetic. The narrow sense of biological material refers to materials that can be used to make various artificial organs and to manufacture medical appliances and products that are in contact with the artificial physiological environment, namely biomedical materials and biological packaging materials.
The bio-packaging materials referred to herein refer to packaging materials in bio-engineering materials. It is defined as the packaging application material that uses biotechnology and is associated with organisms. Or called biological engineering packaging materials.
Second, the status quo and trends of biological engineering packaging materials
The current development of the biomaterial industry is rapid, especially the development of packaging materials and biomedical materials in bioengineering materials.
As regards packaging materials, it is well-known that white pollution is one of the most serious environmental and social problems encountered by countries in the world after industrialization because human production and living activities have abandoned many plastic products that are not naturally degradable in nature. In the past 50 years, the growth in the use of petroleum plastics and various polymers in packaging has been phenomenal. Nowadays, the world produces 1.5X108t worth of $150 billion worth of various plastic-related materials each year. Many solutions have been proposed at home and abroad, but most of them can only partially solve pollution problems or cover them with pollution transfer methods. Now many developed countries have passed legislation to reduce the use of non-environmental plastics, and China has also made corresponding provisions. All these provide a good opportunity for the development and use of biodegradable plastics. At the same time, the world's oil shortage is also a driving force for the sustainable development of biological packaging materials to market. Compared with biological packaging materials, contemporary biomaterials have become more industrialized, and biomedical materials and products have accounted for half of the global medical device market share. In developing countries such as China, the growth of biomedical materials is faster.
It is expected that in the next 15 to 20 years, the biomedical material industry can achieve a scale equivalent to the pharmaceutical market. At the same time, as the frontier research on biological materials continues to make progress, it will open up a broader market space and provide guidance for the improvement and innovation of conventional materials.
Third, several types of hot bioengineering packaging materials
In biomaterials, synthetic biomaterials are the earliest ones studied. Bioceramics, inorganic materials, metals, and alloys are the most studied. One of the earliest applications of metal materials, has a history of hundreds of years. Hydroxyapatite is another synthetic biomaterial that is currently being studied. It is the main inorganic component of mammalian hard tissue. Since the successful synthesis of hydroxyapatite by Japan's Hideki Aoki and Jargro of the United States in the 1970s, it has become a research hotspot for hard tissue repair materials.
With the improvement of people's requirements for environmental protection and the requirement of biomaterials' own biochemistry, natural and semi-natural biological materials have received more and more attention. Natural biomaterials are natural materials formed by biological processes, such as shells, bones, teeth, silk, spider silk, wood, eggshell, and skin. Since biomaterials have evolved over thousands of years, they are simple, and their unique structure results in natural biomaterials that have a combination of many synthetic materials with excellent overall properties. In many of these materials, polylactic acid (PLA) polymerized from biosynthesized lactic acid (PLA) is a typical representative of natural materials. Due to its good performance and the combination of bioengineered materials and biomedical material application characteristics, it has become a To study the most active biological materials.
(1) Polylactide (PLA) Polylactide is a polymer obtained by artificial chemical synthesis of lactic acid produced by biological fermentation, but it still maintains good biocompatibility and biodegradability. It has anti-permeability similar to that of polyester, and has similar gloss, sharpness and processability as polystyrene. It also offers a lower temperature sealability than polyolefins and can be processed using melt processing technology, including spinning technology. Therefore, polylactic acid can be processed into various packaging materials, such as plastic profiles and films for agriculture, construction, and non-woven fabrics and polyester fibers for the textile and textile industries. The PLA's production energy consumption is only equivalent to 20% - 50% of the traditional petrochemical products, and the carbon dioxide gas generated is only the corresponding 50%. In addition to being a packaging material, PLA can be one of the research hotspots in these drug packaging materials and tissue engineering materials. PLA can be made into tissue-engineered scaffold materials that are non-toxic and capable of cell attachment and growth. The scaffold can form a porous structure for cell growth and transportation and nutrition, and can also provide suitable mechanical strength and geometry for supporting and guiding cell growth. Its disadvantage is the lack of the ability to selectively interact with cells. The application of PLA in biomedical materials is extensive and can be used for medical sutures (without suture removal), drug controlled release carriers (reducing the number of administrations and dose), orthopedic internal fixation materials (avoiding secondary surgery), Tissue engineering scaffolds, etc.
There are currently five kinds of PLAs on the international market:
(1) (ECOPLA) Cargill Dow products of the United States. In 1998, a 3,600 t/year semi-industrial plant was built. When the end of the year production capacity was doubled. The Nebrasla plant produced 7X10St PLA in 2002 and reached 1X106t in 2003 (its production capacity was 1.5X106t/year). Cargill Dow first partnered with four companies in Japan that plan to use PLA for packaging materials (Pacific Dunlop, Sony, NTF Docomo, and Mitsdubishi Plastics). And then extended to Europe and the United States (the above information from Cargill Dow's home page: www.cdpoly.com).
(2) LACEA Japan Mitsui Chemicals company product, production capacity 500t/year.
(3) LACTY Shimadzu Corporation produces polylactic acid films. Production capacity 1000t/year.
(4) CPLA Dainippon Ink & Chemical Industry Co., Ltd. has a production capacity of 1000t/year. In the next few years, the company will build several thousand tons of CPLA devices.
(5) HEPLON Chronopol, USA, 2000t/year, plans to build a world-class production facility.
In terms of PLA as a plastic product, Chronopol, a foreign company, reduced the production cost of PLA from 80,000-120,000 yuan/t to 30000-40000 yuan/t; the total domestic production cost was at least 45,000 yuan/t, slightly higher than that of the United States. . The price of general-purpose plastics, such as polypropylene, is as low as 6,200 yuan/t, which is only about 1/7 of that of PLA. In order to use polylactic acid as a large amount of packaging materials and disposable products, its price should be reduced to less than 20,000 yuan/t to have a certain market acceptance. Therefore, accelerating the corresponding research and development has important social benefits. However, at present, the vast majority of PLA's production, processing and application patents are still in the hands of some developed countries. Therefore, we must develop the PLA industry to invest more in basic application research in order to obtain our own independent intellectual property rights. In the future, biosynthesis of artificially synthesized biomaterials and composite research of various materials will receive attention.
The annual production of plastics in the world is 1.5X10St, and 2X105t, which is currently available for PLA replacement (if there is enough production). With the increase in the price of petroleum products, the environmental performance advantages of PLA products are gradually reflected, and PLA will occupy more market share. According to the prediction of relevant experts in Japan, the annual demand for polylactic acid products in the world will reach 3X106t in several years, which will be a great promotion for the development of polylactic acid. Therefore, further reducing the cost of lactic acid fermentation, improving the polymerization process of lactic acid, and improving the application of PLA in tissue engineering will be the focus of PLA research.
(B) Polyhydroxyalkanoates (PHA)
The polyhydroxyalkanoate (PHA), a biopolymer material that has been rapidly developed in the past more than 20 years, is an intracellular polyester synthesized by many microorganisms and is a natural polymer biomaterial. Because PHA also has good biocompatibility properties, biodegradability and thermal processing properties of plastics. Because it can be used as biomedical materials and biodegradable packaging materials, this has become the most active research hotspot in the field of biomaterials in recent years. PHA also has many high value-added properties such as nonlinear optics, piezoelectricity, and gas-phase separation.
Natural or synthetic biodegradable highs: Materials tend to have high water vapor permeability, which is unfavorable in food preservation. PHA, on the other hand, has good gas barrier properties, making it possible to use it in fresh, fresh products for longer periods of time. Because water vapor penetration is an important indicator in fresh-keeping packaging, PHA's performance at this point is completely comparable to that of current PET, PP, and other products. On the other hand, PHA' also has good hydrolytic stability. The PHA was washed with an automatic dishwasher at 75°C for 20 cycles. The shape and molecular weight of cups made of PHA did not change, indicating that PHA can work well. For appliance production. In addition, compared with other polyolefin-based poly-aromatic polymers, PHA also has good UV stability. PHA can also be used as a source of biodegradable environmentally-friendly solvents. For example, ethyl 3-hydroxy-butyrate (EHB) is water-soluble and has low volatility. It can be used as a cleaning agent, adhesive, and adhesive. Ink solvent. Because PHA brings together these excellent properties, it can be obtained in the fields of packaging materials, adhesive materials, spray materials and clothing, appliance materials, electronic products, durable consumer products, agricultural products, automation products, chemical media and solvents. application.
(1) Compared with PLA and other biological materials, the structure of PHA is diversified, and the composition of PHA can be easily changed by changing the bacterial strain, feeding material, and fermentation process. There are obvious advantages. According to the composition PHA is divided into two categories: one is short-chain PHA (monomer is C3-C5), one is medium-long-chain PHA (monomer is C6-C14), these years have reported that the strain can synthesize short-chain and Medium and long chain copolymerized hydroxy fatty acid esters. The production of PHA underwent the first generation of PHA - polyhydroxybutyrate (PHB), the second generation of PHA - hydroxybutyrate copolyester (PHBV) and the third generation of PHA - hydroxybutyric acid copolyester The production of (PGBHHx), while the fourth-generation PHA hydroxybutyric acid (PH-BO) (PHBD) is still in the development stage. Among them, PHBHHx as the third-generation PHA was first mass-produced by Tsinghua University and its partner companies. Compared with the production process of traditional chemical plastic products, PHA production is a kind of low energy consumption and low carbon dioxide emission production, so from the production process to the product is very beneficial to environmental protection.
(2) Another feasible approach to PHA production is to use transgenic plants. The PHA synthesis in plants can use light energy to consume carbon dioxide, making it a sustainable and renewable material production method. The synthesis of different PHAs including PHB?PHBV and medium and long-chain PHA has been achieved in tobacco, potato, cotton, rapeseed, corn, and other plants. Among them, PHA synthesis in potato tubers is the most promising. The current price of PHA is still difficult to compete with petrochemical plastics, while the price of polypropylene is less than 1 US$/kg, while some of the cheapest biodegradable plastics are available at prices of 3-6 US$/Kg, and today’s ideal PHB The production cost is 4 US$/kg. As the scale increases, the production cost will further decrease, but it is difficult to reach 2-3 US$/kg, which is mainly determined by the cost of the bacterial fermentation substrate.
However, through the PHA synthesis of transgenic plants, the cost of PHA is expected to be greatly reduced, because the cost of plants using carbon dioxide and solar energy to produce vegetable oil and starch is 0.5-1 US$/kg and 0.25 US$/kg, respectively, and the PHA extraction process in plants also has For better research, the extraction cost is not higher than the extraction cost of PHA in bacteria. The production of PHA in plants will greatly advance the use of renewable resources for cash crops. The success of this project may make