Application of Polyurethane Adhesive for Several Kinds of Packaging (2)

5. To the development of functional polyurethane adhesives

As the composite packaging material has many advantages, its application field has been greatly expanded, not only in food, medicine, but also in cosmetics, chemicals, detergents, liquid pesticides, as well as construction and decoration materials, heating equipment. Faced with the specific requirements of various industries, the functions of composite materials should be varied. Therefore, the adhesives used in the manufacture of composite materials also develop toward high-quality functionalities.

The so-called functional adhesives are adhesives that meet specific requirements and can be adapted to the specific contents of the package. The scientific and technical personnel of Shanghai Lieyin Chemical Co., Ltd. have conducted more in-depth research on this, and in 1991 they first provided the market with such products. Since then, they have continuously introduced a variety of functional adhesives to form a series of products that are used in various applications. field.

It is no problem to pack dry and neutral contents in compound bags made of ordinary adhesives and use them at room temperature. However, they cannot be packaged with acid, alkali, salty, or spicy media, nor can they be packaged with surfaces. Cosmetics and detergents of active agents cannot even package pesticides or chemicals containing toluene, xylene, ethyl acetate, especially DMF (N,N-dimethylformamide), or other organic solvents. For this reason, it is necessary to have high-quality adhesives with particularly good media resistance. In this field, some foreign brands, such as UK3640/UK6800, are a functional product. LY-50A/LY-50AH, L-103A/LY-103B, LY-135A/LY135B, LY-9850R/LY-9875R and LY-50VR/LY-50VRH, LY-50VH/LY of Shanghai Lianyin Chemical Co., Ltd. -50VNH polyurethane adhesives are also functional adhesives, proving its good resistance to media.

The composite bag of OPP/AL/PE structure produced with LY-50A/LY-50AH adhesive can be used to pack mothballs in addition to 100°C high temperature and resistance to salty, acid, alkali, and spicy media. Disinfection of alcohol, pepper, coffee powder, three-in-one (shampoo, hair dye, hair care) cream such as Shifen, Rejoice, Pantene, Sunsilk and other international brand shampoo, have a very good effect.

High-temperature (≤ 128°C) PET/AL/CPP or PET/AL/OPA/CPP cooking bag produced with LY-9850R/LY-9875R adhesive, and the internal medium is retorted at 124～128°C. The peeling force between /CPP is much higher than that without cooking, and it also shows that it has the prominent function of high temperature resistance. At the same time, the composite bag of this structure can still pack the above-mentioned chemical media. The LY135A/LY-135B increase the heat-resistance temperature to 135°C. They also adapt to plastic/plastic and aluminum/plastic structures.

LY-50VR/LY-50VRH or LY-50VN/LY-50VNH are adhesives suitable for flexible packaging of certain pesticides. They can contain toluene, xylene, ethyl acetate, azone, methanol, alcohol, kerosene and contain 20 % of liquid DMF below DMF.

In the past, the problem of poor opening properties of composite bags was often encountered. In foreign countries, there is a special adhesive that can keep the inner membrane PE coefficient of friction from rising rapidly, such as LX770A. Using this adhesive to produce composite membranes and bags, the increase in the coefficient of friction is generally less than 0.1, which can keep better The smooth opening. Similar products LY-50FT and LY-75FT adhesive developed by Shanghai Lieyin Chemical Co., Ltd. in 2001 are polyurethane adhesives that have both fast curing and minimal increase in PE coefficient of friction. The composite material produced by the use of the composite material is maintained at 45 to 50°C for 12 hours, and it reaches the purpose of ripening, and it can be taken out and cut into bags. Compared with the LX770A adhesive, the friction coefficient has a smaller increase. According to the user's test, the coefficient of friction of the composite inner film produced with the LX770A increases from 0.23 to 0.29, while it is produced with the LY-75FT adhesive. Only increase to 0.27. This type of fast-curing, high-slip, functional adhesive has a strong vitality. It has been used in high-speed automatic filling bag packaging machines and in applications requiring good opening properties. The new LY-103A/LY-103B functionalized aluminized composite adhesive developed by Shanghai Lieyin Chemicals Co., Ltd. in 2003 broke through the limitations of ordinary aluminum-plated adhesives, and its composite products do not Need to select expensive reinforced aluminized film, can use common type vacuum aluminized film (VM-PET, VM-OPP, VM-CPP) production of composite materials with aluminized layer is not easy to transfer, greater peel force and resistance to media The water-resistant and boiled properties greatly broaden the application range of ordinary aluminum plating film. The adhesive can also have high composite fastness for PE films with high levels of smooth release agents (containing more than 800 ppm of additives), which can solve the increase in storage time, increase of additive precipitation, and peeling of such PE film composites. Fatal disadvantage of reducing power.

According to data reports, there are foreign gas barrier adhesives and breathable adhesives, use it to produce composite flexible packaging materials, with ordinary base film can produce high barrier packaging materials or combined with special base film to produce gas Packaging Materials.

6. Research and development of new light-cured, high-performance polyurethane adhesives

In recent years, research and development on UV-curing coatings or adhesives have become increasingly popular. UV-curing adhesives have the characteristics of rapid cross-link curing and energy saving. They are used to increase production efficiency, reduce material inventories, and accelerate capital circulation and small batch speeds. Proofing delivery is very beneficial. Among them, acrylic polyurethane-type UV-curable adhesive is an ideal one, and many papers have been published on the synthesis and properties of such adhesives, but further research and improvement are still needed in the application of composite devices and processes. . If the product development, application equipment, and related technical personnel in the use of process 3 work together and work together, their application in composite flexible packaging materials will also improve.

This type of adhesive can be made into a solvent type or solventless type. If it is made solvent-free, it is more advanced than the existing two-component solvent-free polyurethane adhesives because it no longer requires tens of hours of curing, does not require a curing chamber, and does not require reheat insulation. Consuming heat energy, several processes of compounding, curing, slitting and bagging can be carried out continuously. The time of the production process can be shortened from two to three days to several hours to achieve high-speed production.