Application of the hottest PVDC in food packaging

Application of PVDC in food packaging

ball screw of electronic universal experimental machine of Jinan experimental machine factory part I: performance of PVDC

I. Basic Characteristics of PVDC:

pvdc, scientific name is "polyvinylidene chloride". It is a non-toxic, tasteless, safe and reliable high barrier material. In addition to the general properties of plastics, it also has oil resistance, corrosion resistance, taste retention, excellent moisture resistance, mold resistance, direct contact with food and other properties, as well as excellent printing performance

the main reason why PVDC is widely used in food packaging in the world is that it has high barrier property. Packaging food with PVDC can effectively solve the problem of product deterioration, thus greatly extending the shelf life of products. The high barrier property of PVDC is determined by its molecular structure. PVDC has a linear polymer chain structure connected from head to tail: ·· - CH2 - CCL2 -ch2- ccl2- ·. Due to the symmetry of its molecular structure and the strong agglutination between molecules in the impact test of safety belts, oxygen molecules and water molecules are difficult to move in PVDC molecules. High crystallinity and high density determine that PVDC copolymer has good oxygen separation, gas separation and flavor retention

II. Comparison of the barrier properties of PVDC and EVOH:

at present, PVDC and EVOH have attracted everyone's attention in high barrier materials. In order to facilitate targeted selection, it is necessary to objectively analyze their barrier properties

evoh is a copolymer of ethylene and vinyl alcohol. In a humid environment, it will form a hydrogen bond with H2O, and the absorbed water has a plasticizing effect on EVOH itself, changing the intermolecular force, so that its oxygen resistance decreases rapidly. Therefore, when choosing EVOH, we must consider the influence of humidity on its oxygen resistance. Due to its symmetrical molecular structure and the existence of hydrophobic chlorine, the oxygen barrier performance of PVDC does not change with the change of humidity. Experiments show that when the relative humidity is between 0 and 70%, the oxygen resistance of EVOH (38%) is better than PVDC. When the relative humidity is greater than 70%, the oxygen resistance of EVOH decreases rapidly, which is not as good as PVDC. At 80% relative humidity, the oxygen resistance of PVDC is 3 times better than EVOH, and at 100% relative humidity, the oxygen resistance of PVDC is 13 times better than EVOH. Especially for meat products packaging, the external relative humidity is 60-70%, the internal relative humidity of meat products is 95-100%, and the relative humidity at the packaging material layer is generally more than 70%. Therefore, PVDC is far superior to EVOH in meat products packaging

China has a large land area and significant differences between the north and the south, so we must combine China's national conditions when choosing packaging materials. We know that the three factors that affect the shelf life of products are: the degree of microbial contamination (initial bacterial count), storage temperature and packaging. Next, I will use the choice of packaging materials for low-temperature products to illustrate the impact of temperature and packaging on the shelf life of products

because of its low sterilization temperature, low-temperature products retain most of their nutrients compared with high-temperature products, so they are loved by high-income groups and popularized in western developed countries

the processing technology and packaging materials of low-temperature products in China have also been introduced from developed countries unchanged, but China has not formed a complete cold chain system as western developed countries, so low-temperature products have not been widely promoted in China due to the restrictions of sales conditions. The frequent occurrence of quality problems has become the biggest constraint that restricts the wide promotion and circulation of low-temperature products in the Chinese market

the preservation and quality assurance of meat products usually adopt two ways: low temperature and high barrier packaging. In the case of low temperature, high barrier packaging only plays a preventive role. In the case of low temperature, high barrier packaging really plays a role. At present, EVOH is used as the barrier layer in most of the international low-temperature product packaging. In western developed countries, the cold chain system is very sound, and this packaging form can achieve the purpose of quality assurance at low temperature. In China, terminal sales cannot meet the low-temperature environment required for the circulation of low-temperature products. At this time, we should give full play to the high barrier property of EVOH, but the biggest disadvantage of EVOH is that its oxygen barrier property decreases sharply with the increase of humidity. Generally, the water content of low-temperature products produced in China is relatively high (RH 95%), and EVOH cannot provide due barrier property under this condition. Therefore, the packaging materials with EVOH as barrier layer cannot meet the unique national conditions of China, and the wrong selection of packaging materials affects the promotion of low-temperature products in China. Practice has proved that this problem is completely solved after the barrier layer is replaced with PVDC. It can be seen that the selection of packaging materials has an impact on the shelf life of products. At the same time, it also reflects that the barrier difference between PVDC and EVOH is not only the data on the test report, but also the practical application effect for specific products

objectively speaking, if the packaged products are dry and small packaged foods, and the relative humidity in the circulation and sales environment is low, we recommend that you consider using EVOH. If the barrier requirements are not high in such an environment, you also consider using PA. If you need high barrier property, high moisture content of packaged products or high relative humidity in the environment of circulation and sales, we recommend you to use PVDC

III. comprehensive advantages of PVDC packaged food:

everyone knows that the taste and flavor of products are maintained by the water in the food. In order to maintain the unique flavor and fresh taste of packaged products, high water resistance of packaging materials is required, and PVDC is fully qualified for this requirement (the water resistance of PVDC is better than EVOH); Because of its low gas transmission rate, PVDC also provides outstanding performance to prevent the loss of flavor and maintain the complete flavor. Therefore, packaging food with PVDC has an excellent protective effect on the color, aroma and taste of food, and can provide consumers with a "what you want is what you get" food, that is, what flavor of product you want to provide consumers, through the protection of PVDC packaging, Consumers will get a product of what flavor

in addition, PVDC has a strong price advantage. With the localization and scale-up of PVDC resin, its price is less than half of EVOH, and the application cost can also be reduced by 20% compared with aluminum foil. Therefore, packaging products with this material has excellent cost performance. With the expansion of the application field of PVDC, its application in flexible packaging will have a bright future

at present, due to the global energy crisis, the price of crude oil remains high, and the prices of all petrochemical products rise again and again, causing considerable cost pressure to downstream manufacturers and consumers, while the price of PVDC products is basically stable. The main reason is that the basic raw materials required for the production of PVDC resin are NaCl, limestone and VCM. The first two raw materials account for a large proportion of PVDC resin, and there are rich resources all over the world. With the localization and expansion of PVDC resin in China, the cost of PVDC resin will be basically stable, which may be a good choice for manufacturers struggling to cope with the rising price of packaging materials

IV. environmental protection of PVDC:

1. In the United States, PVDC products are determined to be non-toxic and safe plastic materials, which have been certified by FDA and can be used for food packaging

2. In Germany, PVDC packaging is listed as "green packaging" and holds the green dot mark

3. In Japan, it is confirmed that the incineration of PVDC has no effect on the amount of dioxin produced. At present, PVDC electrodes can continuously monitor their EEG activities in the Japanese market, and the consumption of fresh-keeping film ranks first in the world

4. Using PVDC packaging materials is much less than using ordinary PE film, paper, aluminum foil and other materials, so as to realize the reduction of packaging materials and achieve the purpose of reducing waste sources

at present, many large multinational companies around the world continue to increase their investment in PVDC, and the non environmental prejudice of PVDC sample length of more than 2450mm is defeated in front of the facts

$page break $Part II Application of PVDC

based on the excellent characteristics of PVDC, it is widely used. It is widely used in meat food, convenience food, dairy products, cosmetics, drugs, hardware products that need moisture-proof and rust proof, mechanical parts, military products and other product packages that need high barrier requirements, such as oxygen and corrosion prevention, flavor and fragrance preservation, water and moisture resistance, oil and penetration resistance. The application fields of PVDC varieties mainly include:

first, PVDC casing film

is mainly used for packaging ham sausage, which is resistant to high temperature sterilization, and is suitable for industrial mass production of ham sausage on high-frequency welded automatic sausage filling machine. PVDC is widely used in China, with an annual use of more than 30000t of PVDC resin, such as Shuanghui, Jinluo, Yurun, Meihao, Jiangquan, etc; It is also used in a small amount abroad, such as Japan, South Korea, Vietnam, etc. In order to improve production efficiency, many domestic customers have creatively used large shrinkage casing film to package low-temperature meat products, and have achieved good results

II. PVDC fresh-keeping film

pvdc fresh-keeping film is widely used in household and supermarket packaging food because of its superior transparency, good surface gloss and good self-adhesive; PVDC fresh-keeping film can not only be used to store food in household refrigerators, but also can be used for microwave heating. It has become one of the commonly used packaging materials in developed countries. PVDC fresh-keeping film is well-known in Japan, and has developed into a mature consumer goods, with an annual consumption of more than 25000 tons; In China, due to the carcinogenic effect of DEHA plasticizer used in PVC fresh-keeping film, some manufacturers of packaged meat products have gradually changed to PVDC or PE fresh-keeping film. At present, all the fresh-keeping films used in Shuanghui are PVDC fresh-keeping films. With the improvement of people's living standards, quality of life and the acceleration of the pace of life, PVDC will have a big growth in the industrial fresh-keeping film packaging of conditioned meat and household high-end fresh-keeping film

III. PVDC heat shrinkable film

the structure of PVDC heat shrinkable film is generally pe/eva/pvdc/eva/vldpe (Surlyn), which is produced by coextrusion. PVDC shrink film is mainly used to pack cold fresh meat. By using vacuum packaging machine to pack cold fresh meat, using its characteristics of high shrinkage and high barrier, the packaged cold fresh meat products not only have good appearance, but also can maintain the freshness of cold fresh meat for a long time. In Europe, America, Australia and other places, PVDC shrink film is widely used to package fresh beef products. Packaging fresh beef with PVDC shrink film has become an irreplaceable way to extend the shelf life of fresh beef to a maximum of 2 months. PVDC shrink film is mainly used to pack fresh pork in China, and its freshness can reach more than 15 days

fresh meat is different from meat products. Meat products can be directly consumed by end consumers through packaging, which can cultivate consumers' loyalty to the brand. Fresh meat is often passed to consumers after processing, so that end consumers only know whether there is a problem with raw meat and the processing technology of the processors, and have no impression of the quality of raw meat (Qualitative) and how much (Quantitative), which is not conducive to cultivating the recognition and loyalty of end consumers to the brand of raw meat. By using PVDC shrink film, fresh meat will have its own packaging, so as to have its own brand. In the long run, it will be an effective means for Chinese meat enterprises to promote brands

IV. PVDC coextrusion tensile film

after the Canadian macro company and Dow Chemical of the United States jointly put forward the concept of EVA wrapped PVDC technology, PVDC multi-layer coextrusion technology has been rapidly promoted in the world. In China, there are not only imported multi-layer coextrusion production lines, but also self-developed countries