Case Analysis | Performance Demonstration of Adhesion Promoter Coating in Various Systems

The dilemma of adhesion promoter

In response to strict control of organic volatile compounds in coatings by environmental regulations in various countries, low pollution water-based coatings have developed rapidly. However, due to weak water permeability and poor wetting of substrates, water-based coatings are difficult to form good adhesion on substrates, which has raised consumer questions about the performance of coatings

How to enhance the resistance to peeling and penetration of coatings under extreme weather conditions such as heat, cold, and humidity, as well as long-term erosion by chemical media?

The recommended product this time is Kastar's adhesion promoter series, which stands out among popular products due to its excellent molecular stability, adhesion, and flexibility. It is suitable for various substrates and can efficiently solve current problems.

1. Influence of adhesion promoter

Adhesion promoter is one of the most commonly used methods in the coating industry to improve the coating performance of materials and enhance the adhesion strength of coatings on substrates. It has the characteristics of easy use and significant effects.

△ Bonding force between coating and substrate

As an additive, adhesion promoters exist in the form of small components in coating formulations. However, for different substrates, the choice of adhesion promoter is greatly influenced by the interaction between the coating and the substrate.

1. Sufficient affinity between the coating and substrate 02

2. Able to migrate quickly like the substrate coating interface 03

3. It has the function of removing adsorption of air and water on the surface of the substrate 04

4. Improve the flowability of coatings

2. Test product analysis

Common silane adhesion promoters have an activation period limit in the system, and hydrolysis will occur after a certain period of time, causing sedimentation, flocculation, and even gel formation in the system. This is the phenomenon of hydrolysis, where hydrogen bonds and hydrogen oxygen bonds are dissociated and polymerized, resulting in the dissociation of water molecules.

The tested product is the Kastar adhesion promoter series, which can remain stable in water-based systems for a long time without hydrolysis, avoiding the risk of hydrolysis and solidification of coatings during long-term storage.

△ Partial test products

3. Experimental case presentation

Experimental testing items

Select two-component epoxy and two-component polyurethane systems, add adhesion promoter to component A of the coating, spray and prepare the board, and conduct color difference, gloss, adhesion, impact and other tests;

After being stored in a 60 ℃ oven for 20 days, it was taken out for spray testing again and the two test data were compared and tested.

Comparison of experimental data

△ Comparison of the state before and after thermal storage after adding adhesion promoter

△ Comparison of test data before and after adding adhesion promoter for thermal storage

The above-mentioned products show significant improvement in adhesion and impact resistance of epoxy and polyurethane systems after the addition of adhesion promoters; And after 20 days of thermal storage at 60 ℃, there was no significant difference in performance, and all tests remained stable and unchanged.

Experimental specimen display

1. The substrate is severely rusted and not polished, with an aluminum plate on the right side; The film thickness is 60um, and the hundred grid board is 2mm grade 0 and 1.5mm grade 0;

△ 2KEP+LA SC 0415

2. Makou iron plate, not polished; After thermal storage experiment, 2mm grid plate is OK;

△ 2KEP+LA SC 0415

△ 2KEP+LA 2388

3. After the heat storage experiment, the board was severely rusted and sprayed directly without treatment;

△ 2KEP+LA SC 0415

△ 2KEP+LA 2388

4. The test piece is 60um, the grid plate is 2mm OK, 1.5mm OK, flexible 1mm OK, 1kg * 50cm positive and negative punching OK;

△ 2KPU+LA 1231

5. Copper substrate, film thickness of 20um, 1mm OK for hundred grid board, flexible 1mm OK, 1kg * 50cm positive and negative punching OK;

△ Epoxy varnish baking paint+LA 4F

4. Case Summary

This article only presents some experimental cases focusing on metal substrates, demonstrating the stable performance, excellent adhesion, and improved flexibility of adhesion promoters. The scope of application can cover various substrates.

At the same time, there may be a series of complex chemical reactions between the film-forming base material and crosslinking agent in the coating and the adhesion promoter. When selecting the adhesion promoter, special attention should be paid to the matching of its functional groups with the film-forming resin and crosslinking agent in the coating. If the reaction involving the adhesion promoter leads to an excessive increase in internal stress in the paint film, it will actually have an adverse effect on the adhesion effect of the coating.