The research and development of polyurethane adhesives in my country started in the 1960s. After the 1980s, my country’s research on water-based polyurethane has become more active, but it is still in the development stage compared with the level of foreign water-based polyurethane adhesives. In the 1990s, various industries introduced numerous production lines, and a number of foreign-funded enterprises were established one after another. Imported products urgently needed localization. Relevant scientific research institutes and production units have stepped up development efforts, and new products are constantly emerging.
Polyurethane adhesive refers to a polyurethane adhesive that contains urethane groups or Isocyanate-based adhesive. According to the reaction composition, it can be divided into polyisocyanate adhesives, isocyanate group-containing polyurethane adhesives, hydroxyl-containing polyurethane adhesives and polyurethane resin adhesives. Classification by use and characteristics According to use and characteristics, it can be divided into general-purpose adhesives, adhesives for food packaging, adhesives for shoes, adhesives for paper-plastic composites, adhesives for construction, adhesives for structures, ultra-low temperature adhesives, foaming adhesives, Oxygen adhesives, conductive adhesives, hot melt adhesives, pressure sensitive adhesives, closed adhesives, water-based adhesives and sealing adhesives, etc. But no matter what kind of polyurethane adhesive it is, the isocyanate group in the system reacts with substances containing active hydrogen inside or outside the system to form polyurethane groups or polyurea, thereby greatly improving the strength of the system and achieving the purpose of bonding. .
So far, in addition to the original glue types, solvent-free polyurethane structural glue , reactive polyurethane hot melt adhesive and other foreign types of glue are now basically available in our country. Although my country’s polyurethane industry has a considerable scale, there is still a big gap compared with developed countries, mainly because the output is not large and the technical level is still low. What are the properties of polyurethane adhesives? What fields is it used in? Today I will give you some brief introduction.
1. Characteristics of polyurethane adhesive
1. Strong adhesion, large initial adhesion, wide application range
Because –NCO in the molecular chain of polyurethane adhesive can interact with a variety of active hydrogen-containing The functional groups react to form interfacial chemical bonds, so it has extremely strong adhesion properties to a variety of materials. It can not only bond porous materials, such as foam plastics, ceramics, wood, fabrics, etc., but also can bond a variety of metals, inorganic materials, plastics, rubber, leather, etc. It is an adhesive with a wide range of applications.
2. Outstanding endurance Low temperature performance
at very low At temperatures below – 250°C, general polymer materials are converted into glass and become brittle, while polyurethane adhesives can still maintain high peel strength even below – 250°C. The shear strength increases significantly as the temperature decreases.
2. Polyurethane adhesive Disadvantages and improvement methods
<spanIn recent years, research on improving its water resistance has become a hot topic. At the same time, due to the large heat capacity of water, how to increase its solid content and thereby increase its drying speed is also one of the problems that need to be solved urgently.
5. Polyurethane for construction Adhesive
Polyurethane adhesive has It has the advantages of non-toxic, non-polluting and easy to use. It also has advantages that other adhesives cannot match, namely excellent low temperature resistance, solvent resistance, aging resistance, ozone resistance and bacteria resistance. It plays an important role in the application of building paving materials. effect. It is widely used in elastic rubber floor mats, hard rubber floor tiles and plastic track sports fields.
New two-component polyurethane adhesive breaks through the shear strength and peel strength of traditional adhesives The contradiction allows the two to achieve high strength at the same time. It shows excellent performance in bonding steel plates for construction. The bonding is strong and not easy to deform. The curing speed is adjustable at room temperature, making the polyurethane glue convenient to use. Easy to implement and widely used. Polyurethane adhesives are widely used in constructionPVC material bonding, sandwich panel production and building waterproof coatings.
6. Polyurethane for ink Adhesive
Water-based ink Listed as the first choice for environmentally friendly printing. The normal temperature cross-linked water-based polyurethane adhesive can produce a one-component polyurethane water-based ink suitable for gravure printing. The water-based ink has high gloss and water resistance, strong adhesion, adjustable dryness, bright colors, clear layers, non-toxic and non-flammable, weather-resistant, and easy to control viscosity. , compared with other water-based inks, has wide adaptability to various substrate materials.
Polyurethane—polyacrylic acid As a connecting material for water-based ink, ester combines the properties of polyurethane adhesive and polyacrylate during the drying process of ink film prints. The modified emulsion also has good adhesion fastness to the film.
The base films used in the color printing industry mainly include polyester film, nylon film, and polyester film. There are several types of acrylic films, polyethylene films, etc. Tianjiang Chemical experts remind that the key to choosing ink is that it has good adhesion to these types of base films. Luoyang Tianjiang Chemical New Materials Co., Ltd. uses a new type of polyurethane adhesive made by reacting vinyl chloride-hydroxyethyl acrylate copolymer containing hydroxyl groups in the molecule with macromolecular glycol, small molecule chain extender, and toluene diisocyanate. Effectively improve the quality of color printing ink.
7. For book binding Polyurethane adhesive
nearIn the past 20 years, the application of hot melt adhesive has developed rapidly in book binding. The main reason is that the production of low-priced paperback books has experienced an astonishing growth, and at the same time, wireless binding technology 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 Most of them are EVA hot melt adhesives. However, EVA hot melt adhesive is expensive, and EVA hot melt adhesive has shortcomings such as memory. Polyurethane hot melt adhesive can make up for the above shortcomings. The production process of the adhesive is simple, the cost is low, the adhesive has good elasticity and toughness, the bonding strength is high, the adhesive can be melted and used repeatedly, the product utilization rate is high, and it has broader application prospects.
8. Others
Polyurethane adhesive has excellent adhesion properties It plays an increasingly important role in the bonding of aerospace equipment, protection and restoration of cultural relics, military industry, stationery, medical and health care, etc.
Four. Conclusion
Polyurethane adhesive is widely used in various fields due to its excellent performance, and has increasingly become an important synthetic material in human life. With the gradual expansion of polyurethane uses and the increasing awareness of human environmental protection, the world’s polyurethane adhesive industry is currently developing in the direction of environmental protection, safety and health, and resource recycling. my country’s polyurethane adhesive industry has also shown rapid growth momentum, and technology development has also made great progress.
�Elasticity. Currently, most of the book binding hot melt adhesives used in the domestic market are EVA hot melt adhesives. However, EVA hot melt adhesive is expensive, and EVA hot melt adhesive has shortcomings such as memory. Polyurethane hot melt adhesive can make up for the above shortcomings. The production process of the adhesive is simple, the cost is low, the adhesive has good elasticity and toughness, the bonding strength is high, the adhesive can be melted and used repeatedly, the product utilization rate is high, and it has broader application prospects.
8. Others
Polyurethane adhesive has excellent adhesion properties It plays an increasingly important role in the bonding of aerospace equipment, protection and restoration of cultural relics, military industry, stationery, medical and health care, etc.
Four. Conclusion
Polyurethane adhesive is widely used in various fields due to its excellent performance, and has increasingly become an important synthetic material in human life. With the gradual expansion of polyurethane uses and the increasing awareness of human environmental protection, the world’s polyurethane adhesive industry is currently developing in the direction of environmental protection, safety and health, and resource recycling. my country’s polyurethane adhesive industry has also shown rapid growth momentum, and technology development has also made great progress.
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