What are the characteristics of polyurethane adhesives? What are the application areas of polyurethane adhesives?

Introduction: In our daily life, there are always some items that need to be bonded with adhesives, because some items will be damaged and need adhesives to restore them, and there are also some items that need to be bonded to connect them together to make a new item. Polyurethane adhesive is a very high quality adhesive, widely used in various fields, can be used to stick ceramics, foam, paper wood, etc., can also be used to bond glass, metal, with a very strong chemical adhesion. The following is a detailed introduction to the characteristics and application areas of polyurethane adhesives.

High-performance waterborne polyurethane adhesives have the following characteristics:

(1) Good water and media resistance.

(2)High bonding strength and high initial adhesion.

(3) Good storage stability.

(4)Freezing and thawing resistance, resistance to higher temperatures.

(5) Fast drying, good film formation at low ambient temperature.

(6) Good construction process.

What are the application areas of polyurethane adhesives?

1, automotive polyurethane adhesives

The introduction of a large number of lightweight metals, composite materials and plastics in the structure of the new automobile, resulting in continuous growth of automotive adhesives and sealants. The most widely used polyurethane adhesives in the automobile are mainly assembled windshield with a one-component wet-curing polyurethane sealant; bonding glass fiber reinforced plastics and sheet molding composite materials, structural adhesives, two-component polyurethane adhesives and water-based polyurethane adhesive for interior parts. Automotive interior parts is also an area of growth in the amount of adhesive. In the past quite a long time, China's automobile manufacturing industry has been imported from abroad polyurethane windshield adhesive, until the "Eighth Five-Year Plan" period, the development of this adhesive was included in the national key scientific and technological research projects. Automotive widely used water-based polyurethane adhesive refers to polyurethane dissolved in water or dispersed in water and the formation of adhesives. Most of the water-based polyurethane is linear thermoplastic polyurethane, due to its coating film is not crosslinked, the molecular mass is low, and thus the performance of water resistance, solvent resistance, film strength and other properties are still poor, and it must be modified to improve its performance. Heterogeneous dispersions of polyester and acrylic acid with urea diketone and isocyanuric acid ester with the preparation of automotive repair varnish, do not need high-speed mixing equipment, easy to mix together, with good adhesion properties.

2, wood with polyurethane adhesive

With the sharp decline in worldwide forest resources and the implementation of China's natural forest resources protection project, small wood spelling board requires adhesive bonding strength and durability of weathering and other properties better than the wood itself. The amount of adhesive has become a measure of the level of technological development of the wood industry. In the past, people use wood adhesive is mostly formaldehyde as the main raw material of urea-formaldehyde resin, phenolic resin and cyanuric acid formaldehyde resin, but because of the free formaldehyde exists, the product will be used during the gradual emission of formaldehyde gas to the surrounding area, resulting in environmental pollution. The woodworking industry has begun to focus on the new environmentally friendly adhesive polyurethane adhesive, in order to reduce the pollution of the environment. The one-component, moisture-curing polyurethane adhesives used in the woodworking industry are liquid and are applied at room temperature. They usually have high bond strength, good flexibility and water resistance, and can bond with many non-wood substrates (e.g. textile fibers, metals, plastics, rubber, etc.). One-component polyurethane adhesive in the test showed dry and wet strength are better than phenolic adhesive. Before bonding, coating the surface of the bonding substrate with hydroxymethylresorcinol (HMR) coupling agent can improve the bonding strength, and HMR can strengthen the bonding strength of all thermosetting wood adhesives. When the wood surface is pre-coated with the HMR coupling agent, the strength and durability of the one-component polyurethane adhesive can meet most of the stringent test requirements.

3, shoes with polyurethane adhesive

China is a shoe-making country, the development of footwear adhesive after 3 generations, with the global awareness of environmental protection, as well as the intensification of the oil crisis, prompting the emergence of the 4th generation of environmentally friendly solvent-free and water-based footwear adhesive. In recent years, the preparation process of water-based polyurethane has become more and more mature. For the bonding of some low-polar shoe materials such as SBS, the peel strength of polyurethane adhesives cannot meet the requirements. Through the addition of tackifying resins and other modifications, polyurethane shoe adhesives with high crystallinity, fast crystallization, high cohesive strength and peel strength can be developed.

4, packaging polyurethane adhesive

Flexible packaging, also known as soft cans, with its lightweight and convenient, long freshness, hygiene, easy to store and transport, easy to disassemble, the amount of garbage is small and good shelf effect, such as the unique combination of performance, has now exceeded the rigid packaging such as plastic, glass bottles and cans. Polyurethane adhesive due to its excellent performance, can be different properties of the film material bonded together to get cold, oil, drug, transparent, wear-resistant and other properties of flexible packaging with composite films. At present, in the domestic and foreign markets, polyurethane adhesives have become the main adhesive for flexible packaging with composite film processing. In the domestic adhesive market, packaging composite film manufacturing, polyurethane adhesive dosage is second only to the shoe industry and ranked second. Polyurethane adhesive for packaging a variety of varieties, such as water-based polyurethane adhesive, hot melt polyurethane adhesive, solvent-based polyurethane adhesive, solvent-free polyurethane adhesive. Among them, the commonly used polyurethane hot melt adhesive can be divided into 2 categories: 1) thermoplastic polyurethane elastomer hot melt adhesive: 2) reactive hot melt adhesive. The main disadvantage of thermoplastic hot melt adhesive is high viscosity, so the apparent quality of the coating has a greater impact. Reactive polyurethane hot melt adhesive is a new type of adhesive developed on the basis of traditional hot melt adhesive, which not only has the characteristics of traditional hot melt adhesive with good initial viscosity and excellent post-curing performance, but also has the advantages of polyurethane composition structure and the performance of a wide range of advantages of the adjustment of a wide range of substrate with excellent adhesive properties. In addition, in terms of water-based polyurethane adhesive for packaging, due to the use of emulsifiers or the introduction of hydrophilic ionic groups in the molecule, its water resistance is reduced, and in recent years, the research on improving its water resistance has become a hot spot. At the same time, due to the large heat capacity of water, so how to increase its solid content to improve its drying speed, is also one of the problems that need to be solved.

5, construction polyurethane adhesive

Polyurethane adhesive in addition to non-toxic, non-polluting, easy to use and other advantages, but also other adhesives can not be compared to the advantages of excellent resistance to low temperatures, solvents, aging, ozone and bacterial resistance, in the application of building paving materials play an important role [42]. . It is widely used in elastic rubber floor mats, hard rubber floor tiles and laying plastic runway sports fields. The new two-component polyurethane adhesive breaks through the contradiction between the traditional adhesive shear strength and peel strength, can make both at the same time to achieve a higher use of strength, in the construction of steel plate bonding embodies excellent performance, adhesion is strong and is not easy to produce deformation, and the room temperature adjustable curing speed, so that the polyurethane adhesive in the use of convenient and easy to use, widely used. Polyurethane adhesives are widely used in the bonding of PVC materials for construction, the production of sandwich panels and waterproof coatings for buildings.

6, ink with polyurethane adhesive

Water-based ink is listed as environmentally friendly printing preferred. Room temperature crosslinking waterborne polyurethane adhesive can be made suitable for gravure printing of one-component polyurethane water-based ink, the water-based ink high-gloss water-resistant, strong adhesion, dry adjustable, bright colors, clear layers, non-toxic and non-combustible, resistant to marriages, viscous and easy to control, and other water-based ink, compared to a variety of substrate materials have a wide range of adaptability. Polyurethane - polyacrylate as a water-based ink connecting material in the ink film prints in the drying process, a combination of polyurethane adhesive and polyacrylate performance, the emulsion obtained from the resulting modification of the film also has a better adhesion fastness.

Color printing industry used in the base film are mainly polyester film, nylon film, polypropylene film, polyethylene film and so on several kinds, the key to choose the ink in its response to these kinds of base film have good adhesion. The use of molecules containing hydroxyl vinyl chloride - hydroxyethyl acrylate **** polymer and large molecule diols, small molecule chain expander, toluene diisocyanate *** with the reaction, can be made of new polyurethane adhesive, can effectively improve the quality of color printing ink.

7, book binding with polyurethane adhesive

In the past 20 years, in the book binding, the application of hot melt adhesive has been rapid development. The reason for this is mainly low-priced paperback book production has been a phenomenal growth, at the same time produced a wireless binding process, due to the EVA hot melt adhesive has a very good adhesive and elasticity, the current domestic market for the vast majority of the book binding hot melt adhesive used for the EVA type hot melt adhesive. But EVA-type hot melt adhesive price is expensive, and EVA-type hot melt adhesive with memory and other shortcomings. Polyurethane hot melt adhesive can make up for the above defects, the adhesive production process is simple, low cost, adhesive elasticity, toughness, high bonding strength, adhesive can be repeatedly melted to use the product utilization rate is high, has a broader application prospects.

8, the application of railroad construction

Ballastless track laying (high-speed rail engineering and technology development direction) with glue will be dominated by domestic polyurethane adhesive products, monorail embedded in every 5 meters of a convex baffle, each baffle on both sides of the need to be infused with polyurethane adhesive of about 17.8kg, each kilometer of double-rail ballastless track construction needs polyurethane More than 7 tons of sealing adhesive are needed for each kilometer of double track ballastless track construction. In addition to the laying of railroads, the production of high-speed trains for the use of polyurethane adhesive demand has also greatly increased, polyurethane in the vehicle to assume the role of glass bonding, floor bonding, embedded filler, sealing and waterproofing and other indispensable role in the vehicle, in accordance with the CRH3 as the basis of the moving train set, a single carriage with polyurethane adhesive about 84.07L converted to about 109.3Kg, mainly applied to the car Window glass adhesive sealing and part of the filling parts of the seal.

Conclusion: Through the introduction of the above, I believe that you have a certain understanding of the characteristics and application areas of polyurethane adhesives. Polyurethane adhesive, is a very high quality adhesive, not only has a very strong chemical adhesion, widely used in various fields, and does not have any effect on the air, is a very environmentally friendly chemical adhesive. I recommend you to choose some big brands of polyurethane adhesives, because the quality of big brands of polyurethane adhesives is more reliable. I hope that through the introduction of the above, I can help you understand the characteristics and application areas of polyurethane adhesives.