In the 21st century, people's lives have become more and more convenient. This is because there are many new inventions in life, and these inventions with high functions are inseparable from the invention of new raw materials. Polyurethane adhesive is undoubtedly the best example. . Whether in our daily life or in manufacturing enterprises, there are great uses, commonly used in the bonding of metal, glass, rubber, plastic, foam, wood, leather and other materials. So, what are the manufacturers of polyurethane adhesives on the market? Below I will recommend several polyurethane adhesive manufacturers and related knowledge for everyone, I hope to help you in your purchase!
Brief introduction of polyurethane adhesive
Polyurethane adhesive is an important part of the rapidly developing polyurethane resin. It has excellent performance and has been widely used in many aspects. It is one of the eight important synthetic adhesives.
Polyurethane adhesive has excellent shear strength and impact resistance, is suitable for various structural bonding fields, and has excellent flexibility characteristics.
Polyurethane adhesive has excellent rubber characteristics and can adapt to the bonding of substrates with different thermal expansion coefficients. It forms a soft-hard transition layer between the substrates, which not only has strong adhesion, but also has excellent cushioning and reduction. Shock function. The low-temperature and ultra-low-temperature performance of polyurethane adhesives exceeds that of all other types of adhesives.
Water-based polyurethane adhesives have the characteristics of low VOC content, low or no environmental pollution, non-combustibility, etc., and are the key development direction of polyurethane adhesives.
Classification of polyurethane adhesive
(1) Classification according to reaction composition According to the reaction composition, it can be divided into polyisocyanate adhesive, polyurethane adhesive containing isocyanate group, hydroxyl-containing polyurethane adhesive and polyurethane resin adhesive.
(2) Classification according to usage and characteristics According to usage and characteristics, it can be divided into general-purpose adhesives, food packaging adhesives, shoe adhesives, paper-plastic composite adhesives, construction adhesives, and structures. Adhesives, ultra-low temperature adhesives, foaming adhesives, anaerobic adhesives, conductive adhesives, hot-melt adhesives, pressure-sensitive adhesives, closed adhesives , Water-based adhesives and sealing adhesives.
The principle of polyurethane adhesive
No matter what kind of polyurethane adhesive, the isocyanate group in the system reacts with substances containing active hydrogen in or outside the system to generate polyurethane groups or polyurea, which greatly improves the strength of the system and achieves the purpose of bonding.
Polyurethane adhesive manufacturers
(1) Henghui H-0009 polyurethane adhesive, Guangzhou Henghui Sports Facilities Co., Ltd.
(2) Three 3150 polyurethane adhesives, packaging specifications: 310ml / aluminum tube, Xiamen Norit Industrial Co., Ltd.
(3) Rongneng ZA-302 polyurethane adhesive, packing specification: 3kg, Xianyou County Daji Kirin Craft Supplies Wholesale Department
(4) Huirui HR-728 water-resistant polyurethane adhesive, packaging specifications: 3kg, 15kg, Dongguan Huirui Adhesive Co., Ltd.
Construction technology of polyurethane adhesive
1. Surface treatment: There is often a weak interface layer such as grease or dust on the surface of the adherend. Due to its influence, the bonding strength established on the weak interface layer is not easy to improve. The surface of the substrate that does not match the surface tension of the adhesive must also be chemically treated.
2. Cleaning and degreasing; generally, washing with alkaline water containing surfactants and organic solvents, then washing and drying, or cleaning directly with organic solvents (such as acetone? Carbon tetrachloride? Ethanol etc.). For rusty metals, generally use sandpaper? Wire brush to remove surface rust.
3. Roughening treatment: Roughening treatment is generally required for smooth surfaces to increase the contact area between the glue and the substrate. The adhesive penetrates into the recesses or pores on the surface of the substrate, and after curing, it acts as a "nail, hook, rod" like embedding, which can firmly adhere the substrate together.
4. Metal surface chemical treatment: The metal surface can be derusted? Degreased? Slightly corroded. There are many treatment agents available. Generally it is acid treatment liquid.
5. Surface chemical treatment of plastics and rubbers: Most polar plastics and rubbers only need to roughen the surface and degrease the solvent. However, the surface energy of polyolefin is very low, and the surface polarity can be increased by chemical methods, such as solution oxidation method, corona method and oxidation flame method.
6. Top primer: In order to improve the bonding performance, a thin layer of primer (primer) can be applied on the surface of the treated substrate. The primer can also protect the surface of the adherend just processed from Corrosion and pollution, extend storage time.
7. Preparation of adhesives: Single-component polyurethane adhesives generally do not need to be prepared, and can be used directly according to operation requirements, which is also convenient for the use of single-component adhesives. For two-component or multi-component polyurethane adhesives, it should be formulated according to the instructions. If the hydroxyl content of the components and the content of isocyanate groups are known, the distribution ratio of each group can be determined by chemical calculation. The isocyanate index R = NCO / OH is generally at 0.5-1.4 range. Adding catalyst can accelerate the curing speed of the glue. The curing catalyst is generally an organotin compound.
8. Bonding construction:
a. Coating: The method of coating (gluing) is spraying, brushing, dip coating, roller coating, etc. It is generally determined according to the type of adhesive, viscosity and production requirements. The key is to ensure that the adhesive layer is uniform? No bubbles? No shortage gum.
b. Air-drying: For solvent-based polyurethane adhesives, it needs to be aired for a few minutes to tens of minutes after the glue is applied, so that most of the solvent in the adhesive evaporates, which is conducive to improving the initial adhesion. If necessary, it should be properly heated and blast-dried (such as composite film lamination process). Otherwise, because a large amount of solvent remains in the glue, bubbles are easily formed in the glue layer during the curing process, which affects the bonding quality. For solvent-free polyurethane adhesives, the adherend can be attached after coating.
c. Bonding: This step is to bond the adhesive surfaces of the adhered objects that have been coated with glue. You can also use jigs to fix the adhesive parts to ensure that the adhesive surfaces are fully fitted and positioned, and apply certain pressure when necessary. Make the adhesive better produce plastic flow, so as to infiltrate the surface of the adherend, so that the adhesive can reach the maximum contact with the surface of the substrate.
9. Curing of adhesives: Most polyurethane adhesives do not immediately have a high bonding strength when bonding, and need to be cured. The so-called curing refers to the process of the liquid adhesive becoming a solid, and the curing process also includes post-curing, that is, the reactive groups in the adhesive after the initial curing further react or crystallize to obtain the final curing strength. For polyurethane adhesives, the curing process is to complete the reaction of the NCO groups in the adhesive, or to completely evaporate the solvent? Polyurethane molecular chain crystallization, so that the adhesive and the substrate produce a sufficiently high adhesion process.
Editor's summary: Polyurethane adhesives have many advantages, such as: water resistance, high initial adhesion, freeze-thaw resistance, and high temperature resistance. It is precisely because of these advantages that people will be inseparable from it, and it will be in our It becomes more and more important in life. Polyurethane adhesives are classified in different ways, for example: according to the reaction composition and use.
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