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The current situation and Prospect of water-soluble (PVA) plastic packaging film

I. Introduction

high tech water-soluble plastic packaging film, as a new packaging material, is often prohibited by friction in Europe, America, Japan and other countries. The relative movement between them is widely used in the packaging of products used in water, such as pesticides, fertilizers, pigments, dyes, detergents, water treatment agents, mineral additives, detergents, concrete additives The main characteristics of chemical reagents for photography and gardening care are:

1 Environmental protection, safety, complete degradation (up to 10%), and the final products of degradation are CO 2 and H 2O, which can completely solve the problem of packaging waste treatment:

2 It is safe and convenient to use, avoiding users' direct contact with the packaged goods. It is suitable for the packaging of substances harmful to human body:

3 It can measure accurately and prevent waste

4. Good mechanical properties, heat sealing and high heat sealing strength

5. With anti-counterfeiting function, it can be used as the best weapon for anti-counterfeiting of high-quality products and prolong the life cycle of high-quality products

foreign countries are mainly Japan, the United States, France and other plastic film blowing machine industries. They produce and sell such products according to the diversified market demand, such as w.t.p company, c.c.l.p company in the United States, gransol company in France and synthetic chemical company in Japan. Zhuzhou Institute of technology and Guangdong Zhaoqing Fangxing packaging materials company jointly developed high-tech water-soluble film and its production equipment with the support of the science and Technology Department of China Packaging Corporation. At present, it has been put into production, and its products fill the domestic gap and are going to the market. This paper introduces the composition, production process and characteristics of water-soluble plastic film, and systematically discusses the application prospect of high-tech water-soluble plastic film

II. Production process of water-soluble plastic packaging film

high tech soluble packaging film mainly uses polyvinyl alcohol and starch as the main raw materials, and adds various additives, such as surfactant, plasticizer, anti adhesion agent, etc. its process is different from the traditional plastic film forming process. Its process is: first make the raw materials into water-soluble adhesive with solid content of 18 ~ 20%, Then salivate and apply it to the mirror stainless steel belt. After drying and forming a film, peel it from the steel belt, and then enter the drying room to dry to the specified moisture. After that, cut and roll it to obtain the finished film. The process flow is shown in Figure 1

III. main chemical components and environmental protection characteristics of high-tech water-soluble packaging film

1 Chemical composition

the main raw materials of water-soluble packaging film are polyethylene alcohol and starch with low alcoholysis. Various additives are added by using the film-forming, water-soluble and degradability of polyvinyl alcohol. The additives added are uniformly C, h, O compounds, non-toxic, and compatible with polyvinyl alcohol solution. Only physical dissolution occurs between each component of the additives and polyvinyl alcohol and starch, which improves its physical properties, mechanical properties, process performance and water solubility, but there is no chemical reaction and does not change its chemical properties. Its main chemical components are C, h and o

2. Environmental protection characteristics

high tech water-soluble film products are green packaging materials, which have been recognized by national environmental protection departments in Europe, America, Japan and other countries. At present, biological oxygen demand (BOD) and chemical oxygen demand (COD) are mainly regarded as environmental protection indicators at home and abroad. Relevant Japanese departments have determined that the biological oxygen consumption (BOD) of vinyl alcohol is much smaller than that of starch. The BOD measured by American air products company after biodegradation of PVA products of airvol company for 5 days is lower than 1% of the initial total BOD. Biological tests show that polyvinyl alcohol is not only non-toxic, but also prevents the growth and reproduction of microorganisms, and has no impact on waste treatment and environmental sanitation. The microbial decomposition test of relevant departments also showed that polyvinyl alcohol was almost completely decomposed, which reduced cod very low

in terms of degradation mechanism, polyvinyl alcohol has two degradation characteristics of water and biology. First, it dissolves in water to form glue solution and infiltrates into the soil, which increases the soil's stickiness, permeability and water retention. It is especially suitable for sand soil transformation. PVA in soil can be decomposed by bacteria of Pseudomonas, which are isolated from soil. The symbiotic system composed of at least two kinds of bacteria can degrade polyvinyl alcohol: one is the active bacterium of polyvinyl alcohol, and the other is the bacterium that produces the substances required by the active bacterium of PVA. The oxidation reaction enzyme of secondary alcohol catalyzes polyvinyl alcohol, and then the hydrolase cuts off the oxidized PVA main chain, further degrades, and finally reduces to CO 2 and H 2O

IV. main properties of high-tech water-soluble packaging film

1 Water content

rolled water-soluble films are generally packed with PE plastic to maintain their specific water content unchanged. When the water-soluble film is taken out of the PE package, its water content changes with the ambient temperature, and its performance also changes until it reaches equilibrium

2. Antistatic

water soluble film is an antistatic film, which is different from other plastic films and has good antistatic property. In the process of using water-soluble film to package products, its plasticity will not be reduced and electrostatic dust will not be caused by static electricity

3. Water and gas permeability

water soluble membrane has strong permeability to water and oxygen, but has good barrier to oxygen, nitrogen, hydrogen and carbon dioxide gas. This gives rise to characteristics, so that it can completely maintain the composition and smell of the packaged product

4. Heat sealing property

water soluble packaging film has good heat sealing property, which is suitable for resistance heat sealing and high-frequency heat sealing. The heat sealing strength is related to temperature, humidity, pressure, time and other conditions, generally 100 ~ 200g/cm

5. Mechanical properties

the mechanical properties of water-soluble packaging film are shown in Table 2

6. Printing performance

water soluble film can be clearly printed by ordinary printing methods, with good printability

7. Oil resistance and chemical resistance

water soluble packaging film has good oil resistance (vegetable oil, animal oil, mineral oil), fat resistance, resistance to organic solvents and carbohydrates. However, strong alkali, strong acid, chlorine free radical and other substances that react with PVA (such as borax, boric acid, some dyes, etc.) are not recommended to be packaged with water-soluble film

8. Water solubility

the water solubility of water-soluble films is related to their thickness and temperature, with a value of 25 ц Taking m-thick film as an example, the relevant data are as follows:

v. the application prospect of high-tech water-soluble packaging film

water-soluble film is widely used, has a very broad market, and has environmental protection characteristics, so it has been widely valued by developed countries in the world. For example, Japan, the United States and France have produced and sold such products in large quantities, such as w.t.p company and company in the United States, greensol company in France and synthetic chemical company in Japan. Its users are also some famous large companies, such as bayet (Bayer), Henkel (Henkel), shell (shell), a (aegfu) and other large companies have begun to use water-soluble film to package their products

in China, the water-soluble film market is rising. In terms of the domestic market, according to relevant statistics, the annual demand for packaging film accounts for 20% of plastic products, about 309000 tons. Even if it accounts for 5% of the market, the annual demand is 15000 tons. Its main applications are as follows:

1 Packaging for products used in water, such as gunpowder, chemical fertilizers, pigments, dyes, detergents, water treatment agents, mineral additives, detergents, concrete additives, chemical reagents for photography and chemical reagents for gardening care

2. Water transfer printing, used for trademark and pattern transfer of special-shaped surface of ceramic and electrical shell

3. High temperature water-soluble film (insoluble below 40 ℃) can be used for clothing and textile packaging, food preservation film, etc., especially for export products

4. Used for seed bags, agricultural seedling raising, embroidery, etc

in addition, the main raw material of water-soluble film is polyvinyl alcohol, and China is a large raw material production country, which is beneficial to the market development of the application prospect of high-tech water-soluble packaging film. With the development and progress of society, people pay more and more attention to maintaining our survival environment, especially for China's upcoming integration with international developed countries and the increasing requirements for packaging environmental protection, Therefore, the application prospect of water-soluble films in China must be very broad

VI. future research topic

water soluble packaging film, as a new green packaging material, has just begun its research and application in China and has only 15 years of development history abroad. Therefore, there are many topics to be studied and developed, including the following aspects:

1 Research on quality control methods of water-soluble film production

due to the unique production process of water-soluble film, various defects will occur in production, such as bubbles, uneven thickness, thick edges, "fish eyes", perforations, wrinkles, "craters", etc., and their causes are very complex. The generation of these defects directly affects the application of water-soluble film. Therefore, it is necessary to conduct in-depth research

2. Research on the influence and action mechanism of each component on water-soluble packaging film

various physical and chemical properties of water-soluble film are the result of the comprehensive action of its components. In depth research and Discussion on the influence and action mechanism of each component on water-soluble packaging film is of great significance to improve the quality of water-soluble film, meet user requirements and develop new water-soluble film

3. Improvement and improvement of water-soluble film productivity at present, the production speed of the developed water-soluble film production equipment is 4.5 meters/minute, and that of similar foreign equipment is about 7 meters/minute. Compared with the traditional process of producing non water-soluble film equipment, the productivity is obviously very low, which is an important reason for the high cost of water-soluble film. How to improve the productivity of water-soluble film will be an important research topic in the future

4. Development of new water-soluble membrane and development of new application fields of water-soluble membrane

although water-soluble membrane has been widely used, with the development of production and social progress, human demand continues to grow, and the application of water-soluble membrane needs to be explored in many fields, requiring the development of various new water-soluble membranes. For example, the heat-resistant (300 ℃) water-soluble film used for welding accessories in the power industry to replace water-soluble paper, the development of water-soluble film with washing function in the washing industry to be used as membrane soap, and so on

source: plastic packaging

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