The application advantages of the hottest adhesive

Application advantages of adhesives in flexible packaging (Part 1)

with the development of composite flexible packaging materials in China, polyurethane adhesives for composite have also gone through more than 20 years of history. Since the mid-1970s, Shanghai has first developed the extrusion coating and extrusion composite method to manufacture simple composite flexible packaging materials for food. By the late 1970s, it can be observed by electron microscope and optical microscope, and first developed the dry composite method to manufacture higher-grade composite flexible packaging materials for food, producing composite flexible packaging materials for general 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 to use dry method to make composite flexible packaging materials, in addition to various plastic films and its advantage of automatic temperature control and automatic screen changing aluminum foil substrate, adhesives are also 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 machines, bag making machines, slitting machines and corresponding inspection and testing instruments for the first half of 2017 have played a leading role in the development of China's modern composite flexible packaging industry. 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. The purpose is 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