High-tech water-soluble plastic packaging film is a rising new green packaging material

I. Introduction

High-tech water-soluble plastic packaging film as a novel packaging material is widely used in the packaging of underwater products in Europe, America, Japan and other countries. For example: pesticides, fertilizers, pigments, dyes, detergents, water treatment agents, mineral additives, detergents, concrete additives, chemical reagents for photography, and chemical reagents for gardening. Its main features are: 1. Environmental protection and safety, complete degradation of 10%), the final product of degradation is CO2 and H2O, can completely solve the problem of packaging waste disposal: 2. The use of safety and convenience, to avoid direct contact with the packaged goods, suitable for the packaging of harmful substances, 3. Accurately measure and prevent waste, 4. Good mechanical properties, heat sealable, high heat seal strength, 5. With anti-counterfeiting features, it can be used as the best weapon for anti-counterfeiting of high-quality products, extending the life cycle of quality products.

Foreign countries mainly produce and sell such products from Japan, the United States, and France, such as the American WTP company, CCIP company, France's CREENSOL company, and Japan's synthetic chemical company. The Zhuzhou Polytechnic Institute in China and Guangdong Zhaoqing Fangxing Packaging Materials Co., Ltd., with the support of the Science and Technology Department of China National Packaging Corporation, have jointly researched and developed high-tech water-soluble thin films and their production equipment. They are currently in production and their products are moving into the market. This article introduces the composition, production process and characteristics of water-soluble plastic films, and systematically discusses the application prospect of high-tech water-soluble plastic films.

Second, the production process of water-soluble plastic packaging film

High-tech solvent-based packaging film mainly uses polyvinyl alcohol as the main raw material, and adds various additives such as surfactants, plasticizers, anti-sticking agents, etc. The process is different from the traditional plastic film forming process. The process is as follows: the raw material is first made into a water-soluble glue with a solid content of 18%-20%, and then cast to a mirror stainless steel belt, dried, peeled from the steel belt, and then dried in a drying chamber. After the prescribed moisture content is reached, the finished film is obtained by slitting and rolling. The process flow is shown in Figure 1:

Figure 1 process diagram

Third, the main chemical composition of high-tech water-soluble packaging film and its environmental characteristics

1. Chemical composition: The main raw material of high-tech water-soluble packaging film is low-alcoholicity polyvinyl alcohol. Using polyvinyl alcohol film-forming property, water-solubility and degradability, various additives are added. Its main chemical composition is as follows: Polyethylene Alcohol 78%-82%, surfactant 0.2%-0.3%, plasticizer 10%-12%, anti-blocking agent 0.3%, water 7.5%.

2. Environmental protection features: High-tech water-soluble film products are green packaging materials, which have been recognized by the national environmental protection agencies in Europe, America, Japan and other countries.

At present, BOD and COD are used as environmental protection indicators at home and abroad. Japan's relevant departments to determine the production of polyvinyl alcohol oxygen consumption (BOD) is much smaller than the powder, the United States Air Products's Airvol PVA product biodegradation can be measured after five days BOD lower than the initial 1% of the total BOD. Through biological tests, it has been shown that polyvinyl alcohol is neither toxic nor inhibits the growth and reproduction of microorganisms, and has no effect on wastewater treatment and environmental hygiene. Research on the microbial decomposition tests of the relevant departments also showed that the polyvinyl alcohol was almost completely decomposed and the COD was reduced to a very low level.

As far as the degradation mechanism is concerned, polyvinyl alcohol has both water and biological degradation characteristics. It first dissolves in water to form a glue solution and penetrates into the soil, which increases soil stickiness, air permeability and water retention, and is particularly suitable for sand soil remodeling. PVA in soil can be decomposed by bacteria isolated from the soil, a strain of the genus Pseudomonas. A symbiotic system composed of at least two bacteria can degrade polyvinyl alcohol: one is an active bacterium of polyvinyl alcohol, and the other is a bacterium that produces substances required for PVA-active bacteria. The oxidation of secondary alcohol catalyzes the PVA, then the hydrolase cleaves the oxidized PVA backbone and further degrades, eventually degrading to CO2 and H2O.

Fourth, the main performance of high-tech water-soluble packaging film

1. Moisture content: The rolled water-soluble film is packed in PE plastic to keep its specific moisture content constant. When the water-soluble film is removed from the PE package, its water content changes with the ambient temperature, and its performance also changes.

Table 1 Balanced Moisture of Water-Soluble Packaging Films



45%RH65%RH80%RH
20°C4%-6%8%-9%11%-13%

2. Anti-static property: Water-soluble film is an anti-static film. Unlike other plastic films, it has good anti-static properties. In the process of using water-soluble film packaging products, its plasticity will not be reduced due to static electricity and electrostatic dust will be added.

3. Moisture and gas transmission rate: The water-soluble membrane has strong permeability to moisture and ammonia, but has good resistance to oxygen, nitrogen, hydrogen and carbon dioxide gas. These features make it possible to maintain the ingredients of the packaged product and its own smell.

4. Heat sealability: Water-soluble packaging film has good heat sealability, suitable for resistance heat sealing, high frequency heat sealing, heat sealing strength and temperature, humidity, pressure, time and other conditions, generally greater than 20g/cm.

5. Mechanical properties: The mechanical properties of water-soluble packaging films are shown in Table 2.

Table 2 Mechanical properties of water-soluble packaging films



Performance Index Relative Humidity
45%RH65%RH80%RH
Elastic modulus kg/cm21500-2500800-1700400-1000
Tensile strength kg/cm2300-400250-350200-250
Tear force kg/cm2150-200100-18050-150
The extension rate is 90-150200-300220-300
Temperature 20°C

6. Printing performance The water-soluble film can be printed clearly and smoothly with ordinary printing methods, and the printability is good.

7. Oil resistance and chemical resistance: Water-soluble packaging film has good oil resistance (vegetable oil, animal oil, mineral oil), resistance to fat, organic solvents, and carbohydrates. However, strong alkalis, strong acids, chlorine radicals, and other substances that can react with PVA (such as borax, boric acid, certain dyes, etc.) are not recommended for the packaging of water-soluble films.

8. Water solubility: The water solubility of water-soluble film is related to its thickness and temperature. Take 25μm thick film as an example. The relevant data is as follows:

Table 3 Water Soluble Film Water-Soluble Data (25μm)



Temperature 20°C 30°C 40°C
Dissolution time (s)65-8045-5025-30

Fifth, the application prospects of high-tech water soluble packaging film

The water-soluble film has a wide range of applications, a very broad market, and environmental characteristics, so it has been widely recognized by countries around the world. For example, Japan, the United States, and France have already mass-produced and marketed such products, such as the American WTP company, CCIP company, France's GREENSOL company, and Japan's synthetic chemical company. Its users are also well-known big companies. For example, big companies such as Bayet, Henkel, Shell and Agr.Evaf have started to use water-soluble films to package their products.

In China, the market for water-soluble thin films is booming. According to relevant statistical data, at present, packaging films account for 20% of plastic products each year, which amounts to approximately 309,000 tons, even if the market share is 5%. The annual demand is also 15,000 tons. In terms of price, the excellent and hot domestic products are also very obvious. The current market price of water-soluble film is US$13.17-10,000/t for US products, and RMB20-250/t for Japanese products. The sales price of domestic products is only 40% of the United States, the average selling price of 60,000 yuan / ton.

In addition, the main raw material of water-soluble film is polyvinyl alcohol, China is a big country of raw material production, which is extremely beneficial to the market development of high-tech water-soluble packaging film application prospects, and with the development and progress of society, people pay more and more attention To maintain the environment in which we live, especially as our country is about to integrate with the international developed countries, and the environmental protection requirements for packaging are increasing. Therefore, the application prospect of water-soluble films in China must be very broad.