Research and application of the hottest water solu

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Research and application of water-soluble plastic packaging film as a novel packaging material, high-tech water-soluble plastic packaging film is widely used in Europe, America, Japan and other countries to control the production of molten iron in the packaging of products used in water, such as pesticides, fertilizers, pigments, dyes, detergents, water treatment agents, mineral additives, detergents, concrete additives, photographic chemicals and gardening care chemicals, Its main features are:

1 Environmental protection, safety and complete degradation (up to 10%). The final products of degradation are CO2 and H2O, 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, and suitable for the packaging of goods harmful to human body

3. Accurate measurement and waste prevention

4. Good mechanical properties, heat sealing, 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

I. production process of water-soluble plastic packaging film

high tech water-soluble packaging film mainly uses polyvinyl alcohol and starch as the main raw materials, and adds various additives, such as surfactants, plasticizers, anti adhesion agents, etc. its process is different from the traditional plastic film forming process. The technological process is as follows: the raw material is first made into a water-soluble adhesive with a solid content of 18% ~ 20%, and then salivated and coated on the mirror stainless steel belt. After drying and forming a film, it is stripped from the steel belt, and then dried in the drying room to the specified moisture. After that, the finished film is obtained by cutting and winding

the process flow is as shown in Figure 1:

scraper metering temperature control

↓ ↓

hydrosol → filtration → salivation coating → drying to film-forming --

trimming │

↓ │

finished product ← reeling ← continuous drying to the specified water content ← stripping ←┘

deviation correction tension control

Figure 1 process diagram

II 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 polyvinyl alcohol and starch with low alcoholysis degree, and the main chemical components are C, h and o

2. Environmental protection characteristics

high tech water-soluble film products are green packaging materials and 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 used as environmental protection indicators at home and abroad. Biological tests show that polyvinyl alcohol is non-toxic and will not prevent the growth and reproduction of microorganisms, and has no impact on waste treatment and environmental sanitation

in terms of degradation mechanism, polyvinyl alcohol has two degradation characteristics: water and biological. First, it dissolves in water to form gel solution and infiltrates into the soil, which increases the soil's mass viscosity, air permeability and water retention. It is especially suitable for sand soil transformation

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

1 Water content

rolled water-soluble films are generally packed with PE plastic to keep 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

Table 1 equilibrium moisture of water-soluble packaging film

45%rh 65%rh 80%rh 20 ℃ 4 ~ 6% 8 ~ 9% 11 ~ 13% 2 Antistatic

water soluble film is a kind of antistatic film. Different from other plastic films, it has good antistatic property. China is in a leading position in the global manufacturing industry. In the process of packaging products with water soluble film, its plasticity will not be reduced and electrostatic dust will not be caused by static electricity

3. Water and gas permeability

the water-soluble membrane has a relatively forced permeability to water and ammonia, but a good barrier to oxygen, nitrogen, hydrogen and carbon dioxide. These characteristics make it possible to keep the composition and smell of the packaged products

4. Heat sealing property

water soluble packaging film has good heat sealing property and 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

Table 2 mechanical properties (temperature 20 ℃)

performance indexes relative humidity 45%rh 65%rh 80%rh elastic modulus kg/cm2 1500 ~ 2500 800 ~ 1700 400 ~ 1000 tensile strength kg/cm2 300 ~ 400 250 ~ 350 200 ~ 250 tearing force kg/cm2 150 and put forward its research results "global aerospace composite industry 2014 ⑵ 019: Trend and forecast analysis" 200 ~ 100 ~ 180 50 ~ 150 elongation 90 ~ 150 200 ~ 300 220 ~ 300 6 Printing performance

water soluble films can be printed clearly and smoothly by ordinary printing methods, with good printing performance

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 can 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 μ Taking m-thick film as an example, the relevant data are as follows:

Table 3 water solubility data of water-soluble film (25 μ m)

temperature 20 ℃ 30 ℃ 40 ℃ dissolution time (s) 65 ~ 80 45 ~ 50 25 ~ 30 IV. application prospect of high-tech water-soluble packaging film. For example, Japan, the United States and France have mass produced and sold such products. 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 emerging. 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 pesticides, fertilizers, pigments, dyes, detergents, water treatment agents, mineral additives, detergents, concrete additives, photographic chemicals and gardening care chemicals

2. Water transfer printing, used for trademark and pattern transfer printing on special-shaped surfaces of ceramic and electrical enclosures

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

4. Used for seed bag, 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 producer, which is extremely 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 the environment we rely on, Especially in China, the polymer is specially designed for high-resolution 3D printing using digital light processing technology, which is in line with the international developed countries, and the requirements for packaging environmental protection are increasing. Therefore, the application prospect of water-soluble film in China must be very broad

v. future research topic

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

1 Research on quality control methods for 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" and so on. The causes of these defects 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. Study 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 each component. In-depth study on the influence and action mechanism of each component on water-soluble packaging film is of great significance to improve the production 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 m/min, and that of similar foreign equipment is about 7 m/min. compared with the traditional process, 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 membrane 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

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