1. Woodworking Industry

With the sharp reduction of the world's forest resources and the implementation of my country's natural forest resources protection project, small wood panels require adhesive bonding strength and durability, weather resistance and other properties better than the wood itself. The amount of adhesive used has become a sign to measure the technical development level of the wood industry. Most of the wood adhesives used in the past were urea-formaldehyde resins, phenolic resins and melamine-formaldehyde resins with formaldehyde as the main raw material. However, due to the presence of free formaldehyde, formaldehyde gas will gradually be emitted to the surrounding during the use of the product, causing environmental pollution. The wood processing industry has begun to turn its attention to a new type of environmentally friendly adhesive, polyurethane adhesive, in order to reduce environmental pollution. One-component moisture-curing polyurethane adhesives used in the woodworking industry are liquid and are used at room temperature. Usually it has high bonding strength, good flexibility and water resistance, and can bond with many non-wood substrates (such as metal, plastic, rubber, etc.). The dry and wet strengths of the one-component polyurethane adhesive are better than those of the phenolic adhesive in the test. Before bonding, coating the surface of the bonding substrate with a hydroxymethyl resorcinol (HMR) coupling agent can improve the bonding strength.

Second, the shoe industry

my country is a big shoe-making country. After three generations of development of shoe adhesives, with the improvement of global environmental awareness and the intensification of the oil crisis, the fourth generation of environmentally friendly solvent-free and water-based shoe adhesives has emerged. In recent years, the preparation process of waterborne polyurethane has become increasingly mature. For some low-polarity shoe materials, such as SBS and other materials, the peel strength of the polyurethane adhesive cannot meet the requirements. Modified by adding tackifying resin, etc., a polyurethane shoe adhesive with high crystallinity, fast crystallization speed, high cohesive strength and ideal peel strength can be developed.

3. Packaging industry

Flexible packaging has surpassed hard packaging, such as plastic, glass bottles and cans, with its unique comprehensive properties such as light weight and convenience, long shelf life, hygiene, easy storage and transportation, easy disassembly, less garbage and good shelf effect. Due to its excellent properties, polyurethane adhesives can bond film materials of different properties together to obtain composite films for flexible packaging with various properties such as cold resistance, oil resistance, chemical resistance, transparency and wear resistance. At present, in domestic and foreign markets, polyurethane adhesives have become the main adhesives for the processing of composite films for flexible packaging.

In the domestic packaging composite film manufacturing industry, the amount of polyurethane adhesive is second only to the footwear industry, and ranks second. There are many kinds of polyurethane adhesives for packaging, such as water-based polyurethane adhesives, hot-melt polyurethane adhesives, solvent-based polyurethane adhesives, and solvent-free polyurethane adhesives. Among them, the commonly used polyurethane hot melt adhesives can be divided into two categories: thermoplastic polyurethane elastomer hot melt adhesives and reactive hot melt adhesives. In addition, in the aspect of packaging water-based polyurethane glue, due to the use of emulsifier or the introduction of hydrophilic ionic groups in the molecule, its water resistance is reduced. In recent years, research on improving its water resistance has become a hot spot. At the same time, due to the large heat capacity of water, how to increase its solid content to increase its drying speed is also one of the problems to be solved urgently.

4. Building paving

In addition to the advantages of non-toxic, non-polluting, and easy to use, polyurethane adhesives also have incomparable advantages over other adhesives, namely excellent low temperature resistance, solvent resistance, aging resistance, ozone resistance and bacteria resistance. Application in building paving materials plays an important role in. Widely used in elastic rubber floor mats, hard rubber floor tiles and laying plastic track sports fields. The new two-component polyurethane adhesive breaks through the contradiction between the shear strength and peel strength of traditional adhesives, and can achieve high service strength at the same time. , and the curing speed can be adjusted at room temperature, so that the polyurethane adhesive is convenient and easy to use and widely used. Polyurethane adhesives are widely used in the bonding of PVC materials for construction, in the production of sandwich panels and in architectural waterproofing coatings.

5. Polyurethane adhesives for automobiles

The most widely used polyurethane adhesives in automobiles mainly include one-component moisture-curing polyurethane sealants for assembling windshields; structural adhesives for bonding glass fiber reinforced plastics and sheet molding composite materials, and two-component polyurethane adhesives for interior parts. And water-based polyurethane glue, etc. Automotive interiors are also an area of ​​growing adhesive usage. The water-based polyurethane adhesive widely used in automobiles refers to the adhesive formed by dissolving or dispersing polyurethane in water. Most water-based polyurethanes are linear thermoplastic polyurethanes. Because their coating films are not cross-linked and their molecular weight is low, their properties such as water resistance, solvent resistance, and film strength are still poor, and they must be modified to improve their properties. . The hybrid dispersion of polyester and acrylic acid is combined with uretdione and isocyanurate to prepare auto repair varnish, which does not require high-speed stirring equipment, is easy to mix together, and has good adhesion properties.

6. Others，

In the past 20 years, the application of hot melt adhesives in book binding has developed rapidly. The main reason is that the production of low-priced paperback books has grown dramatically, and at the same time, the wireless binding process has been produced. Because EVA hot melt adhesive has good adhesion and elasticity, the book binding hot melt adhesive currently used in the domestic market is Most of them are EVA type hot melt adhesives. But EVA type hot melt adhesive is expensive, and EVA type hot melt adhesive has shortcomings such as memory. Polyurethane hot melt adhesive can make up for the above defects. The adhesive has simple production process, low cost, good elasticity and toughness, high bonding strength, can be repeatedly melted and used, high product utilization rate, and has wider application prospects.

Due to its excellent bonding properties, polyurethane adhesives play an increasingly important role in the bonding of aerospace equipment, the protection and restoration of cultural relics, the military industry, stationery, and medical care. Polyurethane adhesives are widely used in various fields due to their excellent properties, and have gradually become an important synthetic material in human life. At present, the world's polyurethane adhesive industry is developing in the direction of adapting to environmental protection, safety and health, and resource recovery. my country's polyurethane adhesive industry has also shown a rapid growth momentum, and technological development has also made great progress.