Introduction to primer and precautions for its use

In the field of industrial bonding, primer is an auxiliary product that is often used. Used in conjunction with certain adhesives to improve the bonding ability of certain adhesives to specific substrates. Because it is not an adhesive in the traditional sense, people are often not familiar with it. Today I will talk to you about primer.

1. What is primer?

   An auxiliary material with a very low viscosity that can be evenly coated on the surface of the substrate and can bond the substrate and the adhesive together well. It is used to improve the strength and long-term stability of the bond. Common primers include: glass primers that improve the bonding between glass and adhesives, car body primers that improve the bonding between sheet metal and adhesives, and special primers that improve the bonding between composite materials and adhesives.

2. What are its main ingredients?

Primer is a diluted adhesive whose main ingredients are: solvent (content 60%-70%), solid filler (5%-10%), organic resin (10%-15%), plasticizer ( 1%-5%) etc.

3. What is its main function?

A. It is used to improve the bonding strength between the adhesive and the substrate. The viscosity of the primer is small. It can wet and adhere well to the surface of many difficult-to-stick substrates, so it can act as a bridge. The primer can bind the difficult-to-adhesion substrates. The sticky substrate and some kind of adhesive are well bonded together. B. The primer on the surface of the polished base material also plays the role of filling gullies, thereby solving the problem that the polyurethane glue itself cannot fully contact the base material due to its high viscosity, thus acting as a bridge for bonding.

C. In some metal bonding processes, the primer also plays an anti-corrosion role.

4. What are the precautions for using it?

A. When selecting the type or brand of primer, it is necessary to conduct compatibility tests on the base material, primer, adhesive, and cleaning agent, such as a cross-hatch test or a strip peeling test.

B. The primer contains a certain amount of solid filler and needs to be shaken before use! If it is used directly without shaking, the supernatant of the primer may be applied to the surface of the substrate instead of the mixture of resin and filler, so the bonding effect will not be achieved.

C. When applying the primer, be careful to apply it evenly, in one direction, and with full coverage. The thinner the thickness, the better. The primer will form a hard and brittle film after curing. If the primer is too thick, the bonding strength will be reduced.

D. The surface of the substrate needs to be cleaned before applying primer. Some detergents will cause the primer to fail, so the choice of detergents must also be subject to suitability experiments.

E. The shelf life of the primer will be greatly shortened after the first bottle is opened, so the date of the first bottle opening of the primer needs to be recorded and used as soon as possible. F. After applying the primer, you usually need to wait for the solvent to completely evaporate, usually about 10-30 minutes, and then apply glue after it has completely evaporated. However, secondary pollution caused by long-term storage should also be avoided.

G. Primers usually require low-temperature storage, and the storage environment temperature is too high, which can easily lead to the failure of the primer.

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