Waterborne polyurethane adhesive refers to adhesives formed by dissolving or dispersing polyurethane in water. Some people also refer to waterborne polyurethane as aqueous polyurethane or water-based polyurethane. Waterborne laminating adhesive is a type of waterborne polyurethane adhesive, generally used for film lamination.

The function of water-based laminating adhesive

In the post-press process of the printing and packaging industry, laminating enhances the brightness and water resistance of printed materials, providing a beautiful visual effect for people's lives. With the continuous emergence of various ## processes, ## equipment, and ## adhesives, some new trends have emerged in post-press laminating.

1. The proportion of using water-based laminating adhesives is gradually increasing, while oil-based laminating adhesives are close to phasing out from the market.

When the laminating process first emerged in China, solvent-based adhesives were exclusively used. These were generally single-component SIS oil-based adhesives and two-component polyurethane oil-based adhesives. With the development of science and technology, water-based laminating adhesives have gradually been perfected and formed. People have increasingly recognized the hazards posed by solvent-based laminating adhesives: A. They are highly harmful to operators, as benzene and esters in the solvent can enter human body fluids through the skin, and then enter the bloodstream. Prolonged and high-dose exposure can lead to excessive accumulation in the body, causing various illnesses. B. They are flammable and explosive, with high hazard levels. Major losses caused by this in China have been frequently reported. C. They are costly. D. They increase VOC emissions, causing environmental pollution. E. Solvents remain in the products for a long time, posing a hazard to later users. However, water-based laminating adhesives have successfully overcome the above shortcomings.

II. With the gradual improvement of the production process of water-based laminating adhesives, their cost-effectiveness and special properties have become increasingly prominent.

1. The widely applied and popular water-based laminating adhesive is VAE-based. This adhesive boasts high gloss, strong powder covering ability, and excellent operability. However, it incurs high costs, exhibits poor adhesion, and has poor low-temperature resistance.

2. The successful stabilization and gradual improvement of acrylate polymer lotion in laminating adhesives have ushered in a new era for the widespread promotion of water-based laminating adhesives. Acrylate-based laminating adhesives exhibit strong bonding strength and adaptability, successfully overcoming the shortcomings of VAE-based water-based laminating adhesives.

III. Water-based dry laminating is on the rise:

feature

With the maturity and improvement of water-based dry laminating adhesives, people are increasingly preferring to use water-based adhesives for dry lamination. Although cold laminating machines require less space, consume less electricity, and are easy to operate, their laminated products have poor stiffness and poor adaptability to metallic inks, and many products fail to meet requirements. Therefore, dry lamination will have a broader prospect.

In addition, water-based dry laminating adhesives can be successfully applied on oil-based laminating machines, thus making a significant contribution to the water-based transformation of the entire industry.

Process Used

1. The lamination method is dry lamination, which means the laminating machine should be a dry laminator equipped with a drying tunnel and a heating laminating roller.

2. The temperature of the drying tunnel is approximately 60-95℃. The temperature of the composite pressure roller is approximately 40-70℃, and the composite pressure is approximately 8-20kg.

3. It is recommended that, under permissible conditions, the glue should be dried to 70%-90% dryness. Under these conditions, the composite finished product will have higher brightness and the vehicle speed can be faster. Under these composite conditions, the temperature of the composite pressure roller should be lowered to below 50℃ to prevent large bubbles in the composite product; the pressure should be slightly reduced to prevent the glue from being squeezed out.

4. For gold and silver stamping products, or inks prone to discoloration reactions, as well as gold and silver cardboard, the glue should be ##dried.

5. When using the process where the glue is dried by ##, the higher the temperature of the composite pressure roller, the better, as long as it does not burn the film. The greater the pressure, the better.