Polyurethane Adhesive

Polyurethane adhesive is an important part of the rapidly developing polyurethane resin. It has excellent properties and has been widely used in many aspects. It is one of the important varieties in the eight major synthetic adhesives. Polyurethane adhesives have excellent shear resistance. Shear strength and impact resistance, suitable for a variety of structural bonding areas, and has excellent flexibility properties.

Polyurethane adhesive has excellent rubber properties 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 buffering, reducing shock function. The low temperature and ultra-low temperature performance of polyurethane adhesives exceeds that of all other types of adhesives; waterborne polyurethane adhesives have the characteristics of low VOC content, low or no environmental pollution, and non-combustibility, and are the key development direction of polyurethane adhesives.

There are many components of polyurethane, including polyisocyanates, polyols, auxiliaries, etc., in addition to a variety of auxiliaries and durability auxiliaries. In addition, in order to improve hardness or other properties and reduce the production cost of products, fillers are added during the preparation process, such as thixotropic agents used in polyurethane coatings and sealants used by the company.

The important condition for a good stand-up process is to perform the necessary treatment on the surface of the substrate. For example, the surface of some metal and plastic substrates is often polluted by sweat, oil, dust, etc., so cleaning must be done for a long time, and the surface of the substrate is smooth. It must be roughened to increase the contact area between the glue and the substrate. In addition to these most basic treatments, special treatments are also required for special substrates. For example, some metal surfaces need to be treated with rust removal, degreasing, slight corrosion and other treatment processes at the same time before the polyurethane adhesive can be used.

The first important point of the application technology of polyurethane adhesive is to achieve the effect of completely infiltrating the surface of the substrate by diversifying the surface of the substrate and increasing the pressure in an appropriate amount, and finally obtain a high-strength bonded joint. In addition, the coating amount is also an important factor affecting the shear strength. The shear strength decreases with the increase of the thickness of the adhesive layer. When the thickness of the adhesive layer is between 0.25mm and 1.25mm, the shear strength is ideal; no matter which In all kinds of polyurethane adhesives, the isocyanate groups in the system react with substances containing active hydrogen in or outside the system to generate polyurethane groups or polyureas, which greatly improves the strength of the system and achieves the purpose of bonding.

The variety of polyurethane adhesives provides solutions to many bonding challenges, and is especially useful where other types of adhesives cannot bond or are difficult to bond.

In addition, polyurethane adhesives also have the characteristics of adjustable toughness, simple bonding process, excellent low temperature resistance and excellent stability.

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