Development status of additives for the hottest pl

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Development status of additives for plastic packaging materials (Part 2)

2.3 smoothing agent

during the processing of plastic film packaging materials, there is friction between resin and equipment, which reduces the fluidity of resin, increases energy consumption, and reduces the stability of resin due to friction heat generation, which has a negative impact on the surface of film products, and the film is easy to produce roughness and lose luster. This is very disadvantageous for the increasingly high-speed and automated processing of packaging materials, and the demand for developing new and efficient smoothing agents is increasingly prominent. In addition, during the use of film materials, in order to prevent the film products from sticking together after rolling up, it is also necessary to add a smoothing agent

the common smoothing agents in packaging materials are silicone compounds, amides (such as erucic acid amide, oleic acid amide, etc.) and soaps. The latter two are mostly used in China, and organosilicon compounds are relatively less used. There is a serious problem of precipitation of domestic smoothing agents, and a large amount of frost remains on the roll, which affects the surface quality of the film. In addition, special attention should be paid to the influence on the composite strength of the film in the use of the smoothing agent. Too much smoothing agent affects the use of the adhesive and is not conducive to the composite of the film. There is an urgent need to develop new lubricant products with high smoothness and low mobility to meet the needs. A lot of work has been done abroad in the research and development of organosilicon smoothing agents. For example, the polymerized organosilicon compound of Dow Corning company in the UK not only has excellent smoothness, but also has less precipitation, and will not produce the disadvantages such as the decline of heat sealing performance caused by the migration of ordinary smoothing agents. However, such products still have the problem of poor film printability

as far as PVC products are concerned, smoothing agents can also be called lubricants. Adding lubricant in the production of PVC film can improve its melt fluidity and improve the surface quality of the film. Lubricants can be divided into internal lubricants, external lubricants and amphoteric lubricants according to their uses, and fewer graphene materials can be used in polymers to achieve better conductivity. Lubricants are divided into waxes, fatty acid soaps, lignitic acid and its esters, fatty alcohols and fatty alcohol esters, amides, etc. according to their molecular structures

lubricant is one of the important processing aids of PVC. The lubricant must be matched properly in order to process smoothly and the product has good texture. There are many researches on PVC lubricants abroad, such as G60, g70s and other products of German Henkel company, which have excellent performance and can be used in the production of high-grade PVC films. In China, such as the LC series PVC special lubricant products of Beijing Institute of chemical industry, this is a shuffle, which has the advantages of excellent lubrication effect and little impact on the surface properties of the film, and meets the needs of manufacturers for high-performance lubricants

2.4 heat stabilizer

the research direction of heat stabilizer used in PVC packaging material products is to develop fluid heat stabilizer with the characteristics of high efficiency, low (no) toxicity, less precipitation, light color, light smell and so on. Among them, liquid heat stabilizers used in high-grade transparent PVC thin products (films and sheets) have high requirements for high-efficiency heat stability, low odor, coloring and precipitation of products. Therefore, the domestic market of high-grade liquid heat stabilizers has been occupied by foreign and Taiwan manufacturers for a long time. Because the products of domestic manufacturers cannot meet these performance requirements, they can only compete on low-grade products, and the product technology level is low, It is not conducive to the development of enterprises. Domestic work in the development of high-end products needs to be strengthened. From a technical point of view, the color, smell and other defects of liquid products mainly come from the anionic part of metal salts and solvents. For example, naphthenic acid and c7-9 fatty acid all have pungent odor. Solvents such as transformer oil, diesel oil and kerosene not only have pungent odor, but also do not contribute to thermal stability. Choosing synthetic fatty acids, aromatic acids, organic esters, etc. as anionic groups can solve the above problems. At the same time, considering organic compounds with thermal stability such as phosphite, epoxy esters, etc. as solvents is a development direction, and introducing hydroxyl compounds is also the best policy. At present, the relevant research and development work focuses on the optimization of anionic part of fluid composite heat stabilizer and solvent

another research focus of heat stabilizers for packaging is on the development of non-toxic heat stabilizers to replace heavy metals such as cadmium and lead. Calcium/zinc heat stabilizers have always been one of the non-toxic directions of thermal PVC heat stabilizers, but the long-term problem of calcium/zinc stabilizers is that they have different heat stability efficiency and are difficult to replace organotin, cadmium and lead stabilizers. With the domestic β— The successful development of new varieties of organic heat stabilizers such as diketone and new non-toxic phosphite makes it possible to come out with high-efficiency calcium/zinc heat stabilizers, which can partially or completely replace organotin or cadmium rubber and plastic products in some occasions. The quality and safety of lead heat stabilizers become more important. The MCZ series of liquid or solid composite calcium/zinc stabilizers from Beijing Research Institute of chemical industry is one of the varieties that came into being (Table 3)

rare earth stabilizers have unique Chinese characteristics. Using China's unique rich rare earth resources to develop rare earth heat stabilizers for PVC conforms to China's high-tech industrial policy, is conducive to sustainable development, and is one of the characteristics of China's heat stabilizers. After Jiangyin Huashi industrial commodity chemical plant and Guangdong Zhaoqing Dinghu fine chemical plant successfully developed and produced rare earth heat stabilizers, Guangdong Guangyang high tech Industrial Company successfully adopted the direct process to produce rec series multifunctional rare earth heat stabilizers on a large scale. PEC series stabilizers are non-toxic, tasteless and non radioactive. They have many functions such as coupling, toughening, strengthening and improving processing performance. They have excellent stabilizing effect on PVC and can replace organotin, cadmium and lead heat stabilizers. With excellent performance price ratio, they are a new generation of green environmental protection products

variety development of organic heat stabilizers is still one of the priorities. Organotin stabilizers have significant advantages in transparency and color stability. The development of organotin products focuses on the development of methyl tin and sulfur-free organotin. At present, the production of organotin heat stabilizers in China has begun to take shape. After the 3000t/a organotin plant jointly invested by Beijing Chemical Industry Group Co., Ltd. and American atop company was put into operation, the organotin plant of Shenzhen Fansheng Plastic Co., Ltd. was also put into operation. However, the high-grade organotin products in the domestic market are still occupied by foreign manufacturers represented by Morton plastic additives and akcros chemical company of the United States, and the domestic investment in the development of high-grade organotin varieties should be strengthened

2.5 antioxidants

packaging materials have high requirements for the hygiene of antioxidants due to their special applications, such as packaged food, cosmetics, etc. Although many common antioxidants have been tested for toxicity, it is still inevitable to cause concern in application. Vitamin E has excellent anti thermal oxidation effect and non-toxic side effects, which has been favored by the packaging industry. The active ingredient of vitamin E is α- Tocopherol (ATP), ATP not only has very high antioxidant activity, but also can eliminate or reduce the odor of plastic packaging materials. Therefore, it is introduced into food packaging materials as an antioxidant to replace the previous phenolic antioxidants and achieve good results. First by Switzerland (Hoffmann Laroche company takes vitamin E as polyolefin antioxidant to carry out research work and launch industrialized products. At present, the research and application of vitamin E at home and abroad are increasing day by day.

packaging materials are close to daily life, and the consumption is huge. The recycling and reuse of plastic packaging waste is more prominent, resulting in a greater demand for various new types of special additives for recycled plastics. Among them , the special antioxidant can avoid the disadvantages of yellowing of the resin and substantial reduction in strength during repeated processing, which is conducive to the development of recycling work. Packaging materials, especially film materials, are often composites of various resins. At present, the coordination system of hindered phenol and phosphite widely used by people is not satisfactory for the anti thermal oxidation effect of this mixed system. There is an urgent need to develop antioxidant or processing stabilizer systems for recycling packaging materials

especially when recycling, the performance of plastics has been reduced due to local degradation, and the performance must be properly improved. It is more necessary to have a special stabilizer system. At present, Ciba has successfully developed a new processing stabilizer system, which is specially used for material regeneration, and its trade name is recyclable 660. This auxiliary system, on the one hand, includes high-efficiency antioxidants, which can effectively prevent the decline of molecular weight during processing and maintain the performance of the original polymer. On the other hand, it also contains reactive additives, which can directly react with polymer molecules to improve the molecular weight, so as to improve the use performance

3. Conclusion

on the whole, China has made some progress in the development of functional additives for plastic packaging materials, but there are still many problems. The development and production of high-performance additives can not meet the market demand, and a large number of foreign products are needed. The development and development of functional additives for new packaging materials lags behind the development of packaging materials, It is not conducive to the promotion and application of new packaging technology. China should increase the research and production of functional additives for packaging materials to meet the growing market demand and provide raw materials with different functions for the development of the packaging industry

source: plastic packaging

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