Analysis and Research on the application of the mo

2022-10-14
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Analysis and Research on the application of green food packaging

as we all know, at present, food packaging is a major player in the packaging industry, accounting for about 70% of the packaging industry. Therefore, the waste of food packaging is also the biggest pollution to the environment. In order to better store food and avoid the pollution of packaging waste to the environment, the application of green packaging of food is inevitable

green packaging materials

broadly speaking, green packaging materials are recyclable packaging materials that are harmless to human health, have a good protective effect on the ecological environment in the process of production, manufacturing, use and recycling

1. Reusable and recycled packaging materials

reusable packaging, such as glass bottle packaging of beer, beverages, soy sauce, vinegar, etc., can be used repeatedly. Sweden and other countries implement the reuse of polyester beverage bottles and PC milk bottles for more than 20 times

recycled packaging, such as polyester bottles, can be regenerated by physical and chemical methods after recycling. Physical method refers to the direct and thorough purification and crushing, without any pollutant residue, and the treated plastic can be directly used in the production of recycled packaging containers. Chemical method means that after crushing and washing the recycled PET bottles, depolymerization agents such as methanol water, ethylene glycol or diethylene glycol are used to depolymerize pet completely or partially into oligomers under the action of alkaline catalysts, and then the monomers or oligomers are re polymerized into regenerated PET resin packaging materials after purification

The reuse and regeneration of packaging materials only prolong the service life of polymer materials such as plastics as packaging materials. When their service life is reached, they still face the problems of waste disposal and environmental pollution

2. Edible packaging materials

developing edible packaging materials is the best way to solve the contradiction between food packaging waste and environmental protection. The goal of developing edible packaging is to make a packaging film that does not affect the flavor of the packaged food, and this packaging film is edible. For example, we are familiar with glutinous rice paper used in candy packaging and corn baking cups used in ice cream packaging

pullulan resin, which has been put into industrial production in the 1970s, is an odorless, amorphous, amorphous white powder, and is a non-ionic, non reducing stable polysaccharide. Because it is easy to dissolve in water, it can be used as viscous, neutral and non separable non gelatinized aqueous solution. Its 5% - 10% aqueous solution can be made into a film with a thickness of 0.01mm after drying or hot pressing. This film is transparent, colorless, tasteless, non-toxic, tough, high oil resistance, edible, and can be used as food packaging. Its gloss, strength and folding resistance are better than those of films made of high amylose

there is also an edible fresh-keeping film, which has developed into a multi-component edible film with multiple functional properties, which is made of a variety of biological macromolecules (proteins and polysaccharides) and lipids. This composite film mainly forms a stable emulsion through the interaction between different molecules, and then dries to volatilize the solvent to form a porous, transparent or semitransparent three-dimensional complex structure film. This porous complex structure makes the film have obvious water resistance and certain optional permeability. Therefore, it has broad application prospects in the food industry, especially in the fresh-keeping of fruits and vegetables

3. Degradable packaging material

degradable packaging material refers to a kind of plastic whose chemical structure changes at a specific time and in a specific environment. Degradable plastics not only have the functions and characteristics of traditional plastics, but also can be split and degraded in the natural environment through the action of ultraviolet light in the sun or microorganisms in soil and water after the service life is completed, and finally re-enter the ecological environment in the form of non-toxic and return to nature

degradable plastics are generally divided into synthetic photodegradable plastics, photodegradable plastics with photosensitizers, biodegradable plastics, and multifunctional degradable plastics combined with a variety of degradable plastics. According to the degradation environmental conditions, degradable plastics can be divided into photodegradable plastics, biodegradable plastics (fully biodegradable plastics and partially biodegradable plastics), chemical degradable plastics (oxidative degradable plastics and water degradable plastics), and composite degradable plastics composed of the above three kinds of degradable plastics

among synthetic photodegradable plastics, polyhydroxybutyrate (PHB) and polyhydroxyvalerate (pH stepper, ball screw loading V) are the most widely produced. Their performance is similar to that of polyethylene and polypropylene, and their price is about 10 times that of polyethylene. The degradation principle is that the polymer absorbs ultraviolet light to produce photoinitiation, which weakens the bond energy, splits the long chain into fragments with lower molecular weight, and reduces the physical properties. The fragments with lower molecular weight are further oxidized in the air, producing free radical chain breaking and further degraded into carbon dioxide and water

in the process of plastic processing, adding a small amount of photosensitizer can turn ordinary plastics into photodegradable plastics. This method is simpler and cheaper than copolymerization synthesis method. Photodegradable plastics are mainly used as beverage bottles, shopping bags, garbage bags, mulching films, etc. in foreign countries. Photodegradable plastics researched and developed in China are mainly used for mulching films. In recent years, photodegradable plastics for new disposable fast food boxes have been developed. Because photodegradable plastics can be degraded only under the condition of sunlight irradiation, they are greatly restricted by geographical environment and climatic conditions, so it is difficult to achieve accurate time control, and the buried part cannot be degraded, so the large-scale promotion and application is limited

polymers synthesized from petroleum are difficult to be decomposed by ordinary microorganisms under natural conditions. Both synthetic polymers and natural polymers containing genes prone to hydrolysis have high biodegradability. In China, the incomplete biodegradable plastics mixed with starch and polyolefin plastics are mostly studied. The degradation principle of this kind of plastic is that the starch particles are eroded and consumed by fungi and bacteria first, so as to weaken the strength of the plastic. At the same time, after contacting with some salts in the soil, peroxide is formed by self oxidation, which promotes the breaking of the molecular chain of the polymer in the plastic. They promote and complement each other. Bacteria consume starch, which increases the surface area of the plastic and is conducive to self oxidative degradation. Over and over, the polymer chain gradually breaks and shortens, reducing the strength of the plastic until the molecular weight of the polymer is reduced to the extent that it can be metabolized by microorganisms

4. Paper packaging material

the raw material of paper is mainly natural plant fiber, which will decay quickly in nature, will not pollute the environment, and can also be recycled for papermaking. In addition to the advantages of light weight, low price and shock resistance, pulp molded products also have the characteristics of good air permeability, which is conducive to the preservation of fresh food. In the international commodity circulation, they are widely used in the turnover bags of fragile, fragile and extrusion resistant items such as eggs, fruits and glass products

printing of packaging materials

printing of packaging materials is another important topic involved in green packaging. In particular, ink is composed of pigments, binders, solvents and auxiliary materials. If the pigment contains heavy metals such as lead, chromium, pickaxe and mercury that are insoluble in water, this kind of ink cannot be used for the printing of food packaging and children's utensils packaging. Solvents containing acetone, toluene and methanol should recognize their own advantages and disadvantages, and some aromatic solvents and highly corrosive solvents should not be used

as early as the 1960s, Guangdong Province has developed water-soluble liquid photosensitive resin, which can be used to manufacture water-based UV varnish and water-based UV ink, which can be cured and dried by UV irradiation. During the drying process, the UV light source can be installed on the printing machine, but it should be covered and sealed to prevent burning human eyes. At that time, we studied using black light tubes (i.e. 3 agricultural sterilization lamps ~ 5 in the most widely used conventional plastic granulator equipment) as light sources for liquid resin plates, which can reduce the damage of ultraviolet light to human body, with low cost and simple process

How can food packaging enterprises achieve green packaging

according to ISO14000 series standards, food packaging manufacturers must do the following work to achieve green packaging

1. Establishing an environmental management system

establishing an "environmental management system" (EMS) is the first step for food packaging enterprises to move towards green packaging, just as ISO9000 requires the establishment of a "quality system". Its task is to formulate and implement environmental policies, plan environmental activities, implement environmental management, and conduct supervision and inspection. The core elements of the management system include the company's environmental policy, environmental planning, implementation and operation, inspection and correction, and management review. The management system will ensure that enterprises achieve the goal of green packaging. The environmental policies, objectives and activity plans formulated by enterprises should be compatible with their own attributes, scale, production (activities), products and services' impact on the environment, and have commitments to save resources, prevent pollution and comply with relevant laws and regulations

2. Pass the environmental certification

according to the requirements of ISO14000, packaging enterprises must pass the "environmental certification" (EA) to ensure that enterprises meet the requirements of iso14010 ~ 14019 standards. Quality certification focuses on the "self quality" of products, while environmental certification focuses on the "environmental quality" of products. For food packaging manufacturers, it is not enough to "save resources, reduce pollution and recycle". Enterprises must establish EMS and pass the certification of national authorities. Some food packaging manufacturers in China have taken the lead in passing environmental certification

3. Packages should have environmental signs

environmental signs (EL) are commonly referred to as "green signs". In the future, three kinds of environmental signs introduced by ISO will be implemented worldwide: type I, type II and type III environmental signs

the type I mark specified in ISO14000 is called "ecological mark", which depends on the ecological situation of each country, so there will be great differences between developed countries and underdeveloped countries. Type II sign is the "information sign" of the enterprise's "self declaration". Enterprises disclose their environmental policies, environmental data and information to the society in the form of labels and accept social supervision. Type III mark is the environmental "quality mark" of products, which is marked with specific digital indicators and line segments at the same time, which is more intuitive and convenient. Government agencies of various countries will recommend products and packages with environmental labels to users or consumers

4. Environmental behavior assessment (EPE)

the results are characterized by "environmental behavior index" (Epis). The evaluation results will help packaging enterprises save resources, prevent pollution, and use new technologies and new management systems, so as to make them reach a new level

5. The so-called life cycle refers to the whole process of product (packaging) "material mining → processing and manufacturing → circulation and use → recycling → waste disposal", "coming from the earth and returning to the earth", also translated as "ecological cycle" or "ecosystem". To manufacture any kind of product, we must first "input" materials, energy, manpower, etc., and then "output" products. The "products" of this industry must include the required products, waste, excreta, etc. Therefore, ISO14000 requires that the first-class facility packaging enterprises of Bayer China and Germany textile coating laboratories must carry out the above "whole process" life cycle assessment (LCA) of packaging products, so as to control the "whole process", adopt "zero pollution" or "clean process", and produce "green products" to achieve green

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