What are the characteristics of polyurethane adhesives?

Polyurethane adhesives are adhesives that contain urethane groups (-NHCOO-) or isocyanate groups (-NCO) in the molecular chain. It is divided into two categories: polyisocyanate and polyurethane, because it contains highly polar and chemically reactive isocyanate and urethane groups, so it can have excellent chemical adhesion with materials containing active hydrogen, such as foam, wood, leather, fabric, paper, ceramics and other porous materials, as well as metal, glass, rubber, plastic and other materials with smooth surfaces. The hydrogen bonding between the polyurethane and the material to be bonded increases the cohesion of the molecule, resulting in a stronger bond.

The versatility of polyurethane adhesives provides solutions to many bonding challenges, especially where other types of adhesives cannot be bonded or where bonding is difficult.

Good water resistance and medium resistance, strong adhesion, large initial tack, wide range of application.

Because the NCO in the molecular chain of polyurethane adhesive can react with a variety of functional groups containing active hydrogen to form interfacial chemical bonds, it has strong adhesion to a variety of materials. It can not only bond porous materials, such as foam, ceramics, wood, fabrics, etc., but also bond a variety of metals, inorganic materials, plastics, rubber, and leather, etc., and is an adhesive with a wide range of applications. Good storage stability, outstanding low temperature resistance.

At very low temperatures, general polymer materials are converted into glass and become brittle, while polyurethane adhesives are even at 250?The following can still maintain a high peel strength, and its shear strength increases significantly with the decrease of temperature. The drying speed is fast, the film-forming property is good at low ambient temperature, and the construction technology is good.

The isocyanate group in the system reacts with the substances in the system or contains active hydrogen outside the system to form a polyurethane group or polyurea, which greatly improves the strength of the system and achieves the purpose of bonding.

Bonding of metals, glass, ceramics, etc.:

Metal, glass and other substances have a high surface tension and belong to high-energy surfaces. The PU adhesive cured product contains urethane bonds and urea bonds with high cohesion energy, which can aggregate on the adhesive surface under certain conditions to form a high surface tension adhesive layer. Generally speaking, PU adhesives have a high content of polar groups, a tough adhesive layer, and can be well matched with hard substrates such as metal and glass, and have high bonding strength.

The bonding mechanism between the NCO group and the metal is as follows

Adsorbed water is usually present on metal surfaces (even if there are small amounts of adsorbed water or metal oxide hydrates present on polished metal surfaces), and the urea bonds formed by the reaction of NCO with water and metal oxides are chelated to form an acyl group by hydrogen bonding. Urea-metal oxide complexes, NCO groups can also form covalent bonds with metal hydrates, etc.

In the absence of reactive NCO, van der Waals force hydrogen bonds are created between the hydrates on the metal surface and the metal atoms and the urethane and urea bonds in the polyurethane. The metal surface composition is relatively complex, and the types of various chemical or secondary bonds (e.g., hydrogen bonds) formed between PU glues are also complex.

Inorganic materials such as glass, slate, and ceramics are usually composed of components such as alumina, silica, and calcium oxide, and the surface also contains adsorbed water and hydroxyl groups, and the bonding mechanism is essentially the same as that of metals.

Polyurethane coatingsGenerally less used at home, so there are many people who don't know much about it, but in some public facilities, polyurethane coatings can be described as a big show, not only has a good decorative effect, but also in the construction is a must, it can be said that it is very simple, next, we, take you to understand more polyurethane coating related knowledge.

1. What are the functions of polyurethane coatings?

1. Polyurethane foam, in rigid polyurethane foam, semi-rigid polyurethane foam and flexible polyurethane foam. Rigid polyurethane foam is mainly used for building insulation, insulation materials (such as insulation of pipes and facilities), household items (insulation of beds, sofa cushions, refrigerators, air conditioners, etc., thermal and core materials, such as surfboards) and transportation (cars, airplanes, rail vehicles, seats, roofing and other materials).

2. Polyurethane elastomers, polyurethane elastomers have the advantages of good tensile strength, tear strength, impact resistance, wear resistance, weather resistance, hydrolysis resistance, oil resistance and so on. It is mainly used as a coating material (e.g., protective tubes, gaskets, belts, rollers, gears, pipes, etc.), insulators, solid tires and shoe soles, etc.

3. Polyurethane waterproof material: water-resistant polyurethane material is relatively easy, can be mixed on site, and cured at room temperature after construction. It is commonly used as soil, track and field track material, race track, ground material park, hot window frame.

4. Polyurethane coating, polyurethane coating has strong adhesion, and the coating film has excellent wear resistance, water resistance and chemical resistance. It is mainly used in furniture coatings, industrial coating materials and building materials, printing inks.

5. Polyurethane adhesive can adjust the curing performance by adjusting the ratio of isocyanate and polyol, so as to achieve a high degree of adhesion to the substrate, excellent water resistance, oil resistance and chemical resistance. Polyurethane adhesives are mainly used in packaging, construction, wood, automotive, footwear and other industries.

Second, what are the manufacturers of polyurethane coatings?

1. Texas Aeon Paint **** is a professional sales, water-based coatings, automotive paints, industrial coatings, putty, thinner and other products. Through long-term technology accumulation and continuous product research and development, the company has passed a series of product technologies. The problem is that the current product covers:

Wind power, automobiles, construction machinery, automobiles, trains and other support areas. The company pays attention to the construction of corporate culture in enterprise management, as well as the concept of corporate culture or stuffiness, so as to improve the quality of employees.

2. Shanghai Caiyu Industry Co., Ltd. was established in 2001, specializing in the sales of industrial paints and coatings, which are widely used in engineering construction, all kinds of import and export machinery and equipment, steel structures, valve pipes, advertising posters, etc., equipped with professional paint mixing and color matching equipment, engineering and technical personnel on-site paint and paint.

3. Founded in 2004, Jianneng Building Materials Co., Ltd. is a modern building materials waterproof company specializing in the research, development, production, sales and construction of waterproof coatings, waterproof devices and ceramic tile products. The headquarters and R&D center are located in Guangzhou. There are currently large bases in Guangzhou and Nanjing.

Polyurethane adhesives contain strong polar and chemically active structural molecules, which will make the bond stronger, have excellent adhesion to a variety of materials, and have good impact resistance, vibration resistance, fatigue resistance, wear resistance, oil resistance, solvent resistance, chemical resistance, ozone resistance and bacteria resistance.

Polyurethane adhesive glue disadvantages:

It has poor resistance to strong acid, strong alkali resistance and heat resistance, and is easy to hydrolyze under high temperature and high humidity to reduce the bonding strength, and is sensitive to water, and the adhesive layer is easy to produce bubbles.

Special attention is paid to the fact that polyurethane adhesives have certain toxicity and must be used with caution.

No matter what kind of polyurethane adhesive, the isocyanate group in the system reacts with the substance containing active hydrogen in or outside the system to form a polyurethane group or polyurea, so that the strength of the system is greatly improved and the purpose of bonding is realized.

It can be used for the bonding of DU vehicle windshield and side window glass in the automobile maintenance market, and the welding and sealing of DAO refrigerated compartments and glass inner curtain walls;

It can be used for car body joint sealing, glass caulking sealing, envelope sealing and other general gap sealing.

It can be used for seam sealing of containers, vans, prefabricated houses, and bonding between steel and aluminum.

It can be used to seal the visible parts of the body and general seams of various vehicles, such as skirts, luggage compartment covers, underbody roofs, air conditioners, etc.

Polyurethane is divided into many kinds, elastomers, rigid foam, soft foam, adhesives, we can see in civil affairs, such as the sponge in the sofa in our home is actually soft foam, and the insulation layer of the refrigerator is rigid foam

Access to specialized polyurethane technology**.

China Polyurethane Alliance Network to understand.

Advantage 1, excellent wear resistance.

2. Excellent chemical resistance and oil resistance.

3. Strong adhesion.

4. Low temperature curing performance.

5. High decorative performance.

6. High temperature and low temperature resistance.

Disadvantages: 1. Non-toxicity needs to be built on the basis of the base film, once the base film is not done well or the base film is destroyed, the high pollution of the coating itself will be stimulated.

2. In any case, the aesthetic performance of paint is always quite different from that of wallpaper.

3. It takes a period of ventilation and harmful gas emission after decoration.

Personally, it is recommended not to use paint as the main decoration of a long-term living space. For example, in the bedroom, it is recommended to buy wallpaper instead of paint about the room. **Fei Space has** cheap pvc wallpapers, it is recommended that you can check them out.