Green Packaging Materials Development Technology

Green packaging material is the key to the development of green packaging. Countries all over the world attach great importance and have achieved a series of important results. In order to enable the domestic packaging industry to understand the development of green packaging and better promote the development of green packaging in China, this article describes the progress of the development of green packaging materials, including recyclable or recycled packaging materials, lightweight, thin, and Fluorinated, high-performance packaging materials, biodegradable plastics, natural plant fiber packaging materials, edible packaging materials, agricultural packaging materials, nano packaging materials, transgenic packaging materials, green packaging auxiliary materials and green packaging materials additives.

Recyclable or recycled packaging materials

Many countries in the world attach importance to the development of product recycling technology, and through the deposit recovery system, beer, beverages, soy sauce, vinegar and other glass bottles or polyester bottles are repeatedly used. For example, Sweden and other countries have developed a sterilizing and washing technology that allows PET beverage bottles and PE bottles to be reused more than 20 times. Recycling is a good way to solve solid waste, and it is also an effective way to solve material sources and mitigate environmental pollution. way. Plastic waste recycling technology includes direct recycling of raw materials, physical modification and recycling, chemical modification, recycling and other technologies. The physical method refers to directly purifying the recovered plastic after comminution and then directly to the production of the packaging container, or smashing and washing the polyester and placing it as a sandwich material in the two primary resin layers to form a multilayer PET packaging container; The method refers to the method of pulverizing and washing the recovered PET and depolymerizing the PET into monomers or partial depolymerization into oligomers by using a depolymerization agent such as methanol, water, ethylene glycol or diethylene glycol under the action of a basic catalyst, and purifying the PET after purification. The monomer or oligomer is re-polymerized into a recycled PET resin material.

After the glass and metal packaging containers are discarded, they are generally melted or remelted by remelting and used as raw materials. After the paper and paperboard are discarded, pulp is obtained after disintegration, desorption and bleaching to produce recycled paper.

Degradable plastic packaging material

Currently, biodegradable polymers that have been identified have only biosynthetic fatty polyesters, such as PHB and PH-BV synthesized by fermentation, ether- and polyhydroxy-containing polymers such as starch and cellulose, and synthetic ones. Polyamides, polyurethanes, polymers containing ether bonds, and PVA. Among these polymer materials, polyurethanes, polyamides, polyesters, and PVA are good packaging materials and are widely used as packaging films, packaging containers, or tying materials. However, these types of fully degradable packaging materials are limited, and far from meeting the requirements of numerous packaging technologies and packaging protection performance. However, PHB, PHBV, and polyethers have low melting point and strength and are not very useful.

The incompletely degradable plastics (starch + PE type) blended with starches, also known as bio-disintegrating plastics, are materials that are rapidly researching and developing, have many industrialization results, and are expected to continue to reduce costs. In order to improve the compatibility of starch and polymer blends, it is necessary to modify the starch, and the surface of the modified starch granules is covered with an alkyl group, etc., which weakens the effect of hydrogen bonding, thereby increasing the compatibility with polyethylene and poly. Compatibility of polymers such as vinyl alcohol.

The photodegradable material obtained by adding a photosensitizer can be obtained by adding a suitable photosensitizer to PE, PP or the like. The TPR green packaging material developed by Sweden's Filltec Co., Ltd. is made of calcium carbonate, which is compounded with polypropylene added with a photolysis agent. The composition is very similar to the eggshell, almost harmless to the environment, and can be thermoformed, blow molded, Injection molding and extrusion molding, TPR smooth and smooth, different thickness of the film in the light of 4 - 18 months degradation into powder, is now used in butter, ice cream and other packaging.

Photodegradable packaging materials currently have the following problems: 1 The contradiction between the photodegradation rate and the use of photodegradable polymers. If the photodegradation rate is too fast, it is beneficial to the disposal of waste plastics, to beautify the environment and reduce pollution, but it is obviously detrimental to the performance and life. 2 The effect of photodegradation products on the ecological environment. If the photodegraded product can continue to be biodegraded, eventually becoming carbon or harmless to be absorbed by the microorganism, it is of course ideal. However, in fact, the copolymers of ethylene, propylene and vinyl ketone have very little biodegradability in the soil or underground water channels after photodegradation, and whether the photodegradation products are harmful to the ecological environment are also worth studying.

Currently, biological and light double-degradable plastics entering the market are mainly prepared by blending or grafting modified general-purpose polymers such as PE and PP with degradable polymers such as starch or cellulose. Induced photodegradation of photosensitizers has been studied and applied very actively in this field. Polyketones can be chemically modified with oxidizing agents such as hydrogen peroxide and peroxyacids, and oxidized into polymers containing both polyester and polyketone structure, and become packaging materials having both biodegradability and photodegradability.

Edible packaging materials

Edible packaging materials are now widely used in food and pharmaceutical packaging. The raw materials of edible packaging materials mainly include lakes, proteins, plant fibers and other natural substances. Among the edible packaging materials made from corn, wheat, potatoes, beans, potatoes and other crops, the modification of corn starch into edible packaging materials is the most typical, and the processing technology and practical application are more mature. According to different additives, acid and alkali treatment, enzyme treatment or oxidation treatment method, it can be made into film, or can be extruded to form film clothing for small food, and can also be made into a cup that is both waterproof and oil-proof. And fast food boxes and so on. The use of protein to make edible packaging materials is divided into animal protein and vegetable protein. Animal protein is derived from animal skin, bone, cartilage tissue, etc. This type of edible material has very good strength, water resistance, and oxygen permeability, and is particularly suitable for the packaging of meat foods. Plant proteins extracted from soybeans, etc., can be processed into film to be packaged, have good moisture and oxygen barrier properties, and have certain antibacterial properties, and are suitable for the packaging of fat-containing foods, not only improving the shelf life, but also maintaining the original flavor of oily foods.

Plant fiber edible packaging materials use agricultural and sideline products such as wheat bran, bean dregs, and marine plants such as seagrass and seaweed as main raw materials. Although the nutritional value of this type of material is not high, but many have the role of weight loss and health care, such as sodium alginate, it is not absorbed by the body, but it has blood sugar, regulate the role of the stomach, and can make cholesterol out of the body and have Slow down the effect of poisoning. The plant fibers can be made into various containers, and can be eaten together with the food after being cooked, or when used for packaging instant noodles seasoning, when the heat is applied, the water can be dissolved without being unpacked. It can also produce fresh-keeping wrapping paper for fruits and vegetables. The edible material containing sodium alginate as a main component is impervious to fat and vegetable oil and is an excellent oil-resistant packaging material.

Edible packaging materials can also be made from edible shellfish such as shrimp and crab shells as the main raw material. Chitin can be extracted from chitosan under alkaline conditions. After modification, chitosan has excellent film-forming properties, good oil resistance, moisture barrier and transparency. This type of edible packaging material is now widely used in the packaging of fruit, bread, ice cream and other foods.

Natural plant fiber packaging material

Paper made from wood pulp and straw pulp is the most widely used fiber packaging material. In recent years, some new types of green paper packaging products have been developed. The typical varieties are pulp molding and honeycomb paperboard products. Pulp moulding products use waste paper and plant fibres as raw materials. Molding machines use different moulds to shape certain shapes of products. It is a three-dimensional papermaking technology. Its products are used as substitutes for foamed plastic EPS products and are widely used. In tableware, poultry egg trays, fruit trays, industrial trays, food and medical device packaging. Honeycomb paperboard is composed of upper and lower two face papers and hexagonal honeycomb core paper. It has the advantages of light weight, high strength, high stiffness, good cushioning, heat insulation and sound insulation. It is made of wood and substitute EPS. The ideal environmental protection material for cushioning pads.

In particular, natural plant fibers refer to natural fibers other than trees, such as bagasse, cotton stalks, husks, corn stalks, rice straw, wheat straw, and waste paper fibers. Naturally occurring plants are a source of abundant renewable resources. Natural resources. In recent years, a series of green packaging products have been developed using natural plant fibers such as reeds, rice straw, wheat straw, bagasse, and bamboo. Take bamboo as raw material to produce bamboo plastic packing box and silk bundle box for packaging of mechanical and electrical products and heavy machinery; bamboo fiber, rice straw and other plant fibers are pressed into fiberboard after high temperature sterilization, and then pulverized and added into padding. Materials, adhesives, etc., after extrusion molding, can be made disposable fast food equipment, such as the expansion of the foam can also be made cushioning.

Transgenic plant packaging materials

Although breakthroughs have been made in the research and development of biodegradable packaging materials using microbial fermentation, there are still low productivity, low temperature difference between melting point and degradation, slow crystallization rate, difficult processing, and high cost. Limitations and other issues. Therefore, the development of genetically modified plants to produce fatty polyesters PHB and PHAs has become a hot spot for the research and development of biodegradable plastics.

With the rapid development of plant genetic engineering, the production of PHB for microbial fermentation is expensive, and some large companies have successively developed PHB packaging materials using transgenic plants as reactors. The long-term goal set by the UK's ICI/Zeneca Seed Company is to introduce the pathway for bacterial biosynthesis of PHB into suitable crops for the large-scale production of PHB/V packaging materials using transgenic plants; the Monsanto Company of the United States launched a major project in 1996 with the aim of Establish a technical system for the production of packaging materials using genetically modified rapeseeds.

According to reports, two key enzyme genes (phbB and ph2bC) synthesized by PHB have also been cloned from Alcaligenes eutropha in China, and the prokaryotic vector has been successfully introduced into E. coli. It has also been successfully introduced into potato. In order to increase PHB production, they completed the cloning of the phbA gene and constructed a seed-specific expression vector for the transformation of rapeseed. The gene product will be located in rapeseed on-demand plastids.

Lightweight, thin, non-fluorinated, high-performance packaging materials

This is an important direction for the development of green packaging materials. It is mainly for the development and deep processing of existing packaging materials. On the basis of guaranteeing the realization of three major functions of packaging, reforming excessive packaging, developing appropriate packaging, minimizing the use of packaging materials, and reducing Packaging costs, saving packaging materials resources, reducing the amount of waste generated packaging materials, and strive to develop a lightweight, thin, non-fluorinated, high-performance new packaging materials.

For a large amount of buffer packaging materials, people are actively looking for non-fluorinated lightweight packaging materials to replace expanded polystyrene (EPS), such as the use of new lightweight foamed polyester or foam PP packaging containers for In the packaging of foods, cosmetics and electronic products, various foaming agents such as methylene chloride are used in various countries to substitute freons (CFCs) that cause environmental pollution.

For packaging paper and paperboard with a large amount of usage, in order to meet the special requirements of product packaging, it has also been developed in a variety of ways toward versatility and high performance.

Nano Packaging Materials

Nanomaterials are materials that are at least one dimension in the three-dimensional space in the nanometer size range or consist of them as a basic unit. It is the most basic component of nanotechnology. Nano packaging material refers to a new type of packaging material in which the dispersed phase size is 1 to 100 nm, which is synthesized or added to powders and other packaging materials or nano-modified traditional packaging materials, and also refers to a part of nano-materials that can be used to package products. They can be referred to as nanocomposite packaging materials, nano-modified packaging materials and pure nano packaging materials. For the nanocomposite packaging materials, the material structure system is more subtle and more dispersed, and the nanocomposite packaging material cannot have the traditional composite packaging material because of the small size effect, surface effect, quantum size effect, and macroscopic quantum tunneling effect of the nanoparticles. Some of the more specific properties, such as high strength, high hardness, high toughness, high barrier properties, high resistivity, low thermal conductivity, low elastic modulus, low density, high degradability and high antibacterial ability.

Nano-modified packaging material refers to by adding a small amount of the table