On the advantages of using adhesives in flexible p

With the development of composite flexible packaging materials in China, polyurethane adhesive for composite has also gone through a history of more than 20 years. Since the mid-1970s, Shanghai has first developed composite flexible packaging materials for simple food by extrusion coating and extrusion composite methods. In the late 1970s, it has first developed composite flexible packaging materials for higher grade food by dry composite methods, from general composite flexible packaging materials for simple food to plastic/plastic cooking bags that can withstand 121 ℃ high temperature cooking for 40 minutes and more advanced aluminum/plastic cooking bags. At the same time, dry composite adhesives are also developed synchronously

we know that the dry method should be used to make composite flexible packaging materials. In addition to various plastic films and aluminum foil substrates, adhesives should also be used. The one component solvent-based pressure-sensitive adhesive made of butyl rubber was first used. By combining pet, Pt and PE films, it can be made into the simplest and most primitive composite flexible packaging material, which is used in the packaging of compressed biscuits, candies and pickles. By the end of the 1970s, due to the development of cooking bags that can withstand 121 ℃ high temperature cooking for 40 minutes, one component pressure-sensitive adhesive was obviously not feasible. Therefore, Shanghai was the first to develop two-component high-performance polyurethane adhesive. Of course, this kind of adhesive has been industrialized in China since the 1960s, but because its performance does not meet the requirements of composite flexible packaging, it has shortcomings such as high boiling point of solvent, serious odor, too many residual monomers, unreliable sanitary performance, and too small initial adhesion, and cannot be used in dry compounding to produce qualified food packaging materials, so we should aim at the level of the United States and Japan at that time, Redevelop and research a two-component polyurethane adhesive that conforms to food hygiene and safety and can withstand cooking at 121 ℃ for 40 minutes. After more than two years of research, it finally passed the appraisal of the national science and Technology Commission and the Ministry of light industry in August, 1981, and completed this task

since 1980, China has gradually reformed and opened up, the people's living standards have been significantly improved, the market economy has become increasingly active, the food industry has developed rapidly, and the main and non-staple foods have become increasingly abundant. The voice for improving packaging has also risen, and the demand for composite flexible packaging materials is great. Therefore, Shanghai, Wuxi and Dalian first introduced relatively advanced production lines of composite flexible packaging materials from Japan, including multi-color combined gravure color printing machines Dry compounding machine, bag making machine, slitting machine and corresponding testing instruments have played a leading role in the development of modern composite flexible packaging industry in China. However, intaglio inks, adhesives, pet, OPP, OPA, CPP, aluminum foil, etc. required for the production of composite flexible packaging materials should be imported

in order to meet the needs of domestic composite flexible packaging production, since the first half of the 1980s, all parts of the country have vigorously developed flexible packaging production equipment. Flexible packaging machinery production enterprises in Shanghai, Wuxi, Haining, Guangdong and other places have mushroomed rapidly, and flexible packaging material production enterprises for composite color printing have also flourished, resulting in a sharp increase in the demand for imported gravure ink and dry composite adhesive. In this situation, the production technology of polyurethane adhesive for food composite packaging materials in Shanghai has the soil for industrial production. Therefore, China's food grade polyurethane adhesive production base with an annual output of 60 tons was first established in 1984. With this model base, the packaging industry has seen the hope and Prospect of adhesive localization. In just two or three years, two or three places have successively built enterprises with an annual output of about 500 tons, officially launching the climax of adhesive localization. In the mid-1980s, Beijing Research Institute of chemical industry cooperated with German Henkel company to produce solvent based two-component polyurethane adhesive for dry compounding in China by using the technology provided by Henkel. However, there is no cooperation in the production technology of the curing agent, and it has to be imported from Germany and used together with the domestic main agent after subpackaging. Later, through their own development and research, they mastered the production technology of curing agent, and then used the domestic curing agent to replace the imported products and use it together with the main agent produced in China

polyurethane adhesives produced by domestic technology in the 1980s, on the one hand, have relatively few varieties, and are mostly used in low and medium-grade composite flexible packaging materials with low requirements. On the other hand, there are some defects in quality, such as the viscosity of the glue is too high, the frost resistance is poor, and it is easy to freeze in winter. When using, it is necessary to heat it to 50 ~ 60 ℃ and melt it before pouring it out of the packaging barrel to prepare the operating solution. On the other hand, The adhesive film has few functions, the adhesive force is not very high, and the anti medium ability is very poor. Therefore, although there are many output and users, they still have opinions on this product. Some large factories are willing to buy and use adhesives produced in Germany, Japan, the United States and France at a high price. Since the late 1980s, researchers in Shanghai have studied functional adhesives in addition to aliphatic high-temperature cooking adhesives that meet the specifications of FDA and fill the domestic gap, in order to solve the quality problems of Sichuan mustard and Zhejiang mustard soft packaging bags in China. It turned out that the opp/al/pe mustard bag made of domestic adhesive at that time was not resistant to acid, salty and spicy corrosion. After the packed mustard was soaked in hot water at 80 ~ 90 ℃ for 10 minutes, the inner PE and Al had been automatically layered, resulting in the bag breaking and leakage of mustard before it was put on the market. The mustard factory claimed against the packaging material factory. After about two years, Shanghai Shenhua Technology Co., Ltd. first introduced to the market in 1991 a special adhesive for aluminum foil, which is resistant to acid, spicy and salty medium corrosion and can withstand 100 ℃ boiling. It was used by Zhejiang and Fuling color printing plants to make mustard bags, which solved the problem. In the next few years, due to the wide use of the adhesive, the phenomenon of complaints or claims from pickled mustard producers to color printing packaging materials factories should be reduced year by year, and there was only one case by 1996. It was unimaginable that the adhesive produced by Shanghai technology also solved the quality problem that the aluminum coating needs to be transferred and the peeling force is zero after the aluminum coating is compounded, which can improve the composite fastness of vacuum aluminum coating such as m-pet and m-CPP from the original, to more than 1n/15mm, the best of which can reach 3 ~ 4n/15mm, and the aluminum coating will not be 100% transferred. In more than a decade, it has been designated as aluminum coating The special adhesive for jelly cover and acid resistant, salty and spicy composite film is also designated as the adhesive for wine film composite by the soft wine bag composite manufacturer. Due to the reliable and stable quality of this adhesive, it was also exported to Singapore in the first half of the 1990s, becoming the first and only export product of domestic adhesive

with the increasing application scope of composite flexible packaging materials, it is not only used in the packaging of food and drugs, which is of great significance to build a new international competitive advantage, but also used in the packaging of daily necessities, cosmetics, washing products, sanitary products, pesticides and some chemicals, so the functional requirements are more urgent. Therefore, the share of Shanghai lieyinhua biomedical materials founded by Shanghai Shenhua technology company will meet that of pharmaceutical market industry Co., Ltd. since the beginning of 1997, the quality of adhesive has been improved again on the original basis, so that the function of special adhesive for aluminum foil is more comprehensive and the application field is further expanded. Finally, the concept of functional adhesive was put forward for the first time in the middle of 1998, At the same time, functional adhesive products are introduced to the market. Some of this series of functional adhesives have the functions of resisting acid, alkali, spicy, salty and oil, others have the functions of resisting the corrosion of benzene, toluene, xylene, ester, hydrocarbon, wine, surfactant, DMF organic solvent mixture with content less than 20% and pesticides, and others are suitable for plastic/plastic and aluminum/plastic composites cooked at 128 ℃ for a long time (even 120 minutes). Among the functional products, the company has ly-50a/ly-50ah, ly-9850r/ly-9875r, ly-50vr/ly-50vrh, ly-9850/ly-9850h and other models

since the industrial production in the mid-1980s, the adhesives used for composite flexible packaging in China have grown from scratch. There are about 300 production enterprises from a few to the present. The varieties range from single to multiple, the quality from medium and low grades to high grades, and the types range from ordinary to functional and then to special types. It can be said that there are some adhesives in the world, including ordinary adhesives, functional adhesives, plastics/plastics, aluminum/plastics, low temperature resistant adhesives High temperature resistant glue, aromatic glue and aliphatic glue, including food packaging glue, pesticide and chemical packaging glue, solvent-based glue, solvent-free glue, non flame retardant glue and flame-retardant glue

as mentioned earlier, at present, nearly 300 enterprises in China are producing adhesives for composite flexible packaging, and the equipment capacity has reached 100000 tons per year, far exceeding the market demand of 30000 to 40000 tons. However, due to the different technical levels and development and research capabilities of various enterprises, the quality of products is uneven, and the adaptability of products is also different. Therefore, there is still a large gap between the adhesive products of some production enterprises and imported or domestic famous brand products. In order to attract everyone's attention and the healthy development of adhesives, the author talks about three issues here

first, the product quality of some enterprises is not stable enough and fluctuates greatly. Most of these enterprises have been established in the past three to five years. Their foundation is too shallow, their technical skills are not thick, and their personnel quality is not high. In particular, the first-line production personnel are not rich in experience, and their quality control methods are not smart and stable

therefore, the author believes that the more you know, the better you can do. At present, some domestic enterprises obtain the production technology of adhesives by improper means, or secretly buy processes and formulas, or secretly recruit personnel, hire consultants, etc., but they do not fundamentally master the comprehensive technology. They only get some surface parts, and have not mastered the key core content. Their products have shortcomings, although they also pat their chest when promoting, saying: my product quality is the same as the brand, and the price is cheap, You can use it safely, but after real comparison and strict testing, you will find that it will take time to truly achieve superior quality and long-term stability. There is another problem, that is, as users, we should learn a lesson. Don't pursue too much cheapness. When choosing any raw and auxiliary materials, we should put quality first and price second. Without quality, there will be no quantity, no output, and no cost and benefit! Just think, how to estimate the loss of using inferior adhesives and making scrapped products? Therefore, the author believes that all enterprises producing adhesives should work hard to refine basic skills, strengthen technical training, strictly control and supervise quality, improve product quality, and do not easily launch uncertain new products

second, adhesive manufacturing enterprises should follow the principles of seeking truth from facts, honesty and credibility, oppose and stop the exaggerated and impetuous unscientific mentality, and do not practice fraud, shoddy, and misleading consumption. In the previous two or three years of investigation, it was found that the low solid content of adhesive and the lack of weight of packaging caused users to suffer losses. This practice is inconsistent with the actual situation of adhesives for composite flexible packaging in China