UV curing paint is a kind of green environmental protection paint, which has the characteristics of high transparency, high hardness and scratch resistance. It is widely used in plastic or metal substrate oil spray process. The outstanding phenomenon that affects the coating quality and yield in UV spraying is paint falling, that is to say, the adhesion between UV curing paint and substrate is poor. Then we will analyze the causes and solutions of difficult adhesion from two aspects of UV paint and spraying substrate.
Reasons why UV curing paint is difficult to adhere to the substrate:
From the analysis of UV curing paint, the effect of UV coating on the substrate is weak in terms of penetration. Considering the performance after curing, the viscosity of low molecular weight resin system increases and the fluidity decreases, so the wetting and penetration of substrate are not enough. Furthermore, the volume shrinkage of UV paint during curing and the time of rapid reaction are two aspects. The former will cause the difference in deformation between coating and substrate, thus forming stress between coating; The latter is due to the rapid reaction, which will cause the non-uniformity of UV paint system structure.
From the perspective of the substrate of UV paint spraying, the first thing to understand is the role of adhesion. The strength of its existence determines whether the paint and the substrate can obtain adhesion to form a solid coating. So here we have to say the influence of substrate polarity, crystallinity, surface energy and smoothness on substrate surface adhesion. Low non polarity or polarity, such as PP plastic, which is difficult to oil, high crystallinity and low surface energy, such as PA nylon substrate, while the smoothness is more prominent in stainless steel metal. Therefore, the molecular structure and properties of the substrate also have a great impact on the adhesion. Therefore, when the UV paint can be adjusted, the key to solve the problem of poor adhesion of UV paint is to improve the adhesion between the substrate and the UV paint.
Methods to enhance the adhesion between UV paint coating and substrate:
In the method of solving the adhesion of UV curing paint sprayed on plastic or metal surface, a layer of static paint is sprayed on the surface of the substrate Sichuan adhesive treatment agent is an effective solution to enhance the adhesion between the substrate and the UV coating. Firstly, the adhesive treatment agent can fully wet the substrate. Secondly, the treatment agent contains hydrogen bonded free radicals with polar groups such as hydroxyl of the substrate, which makes the film more compact. At the same time, the adhesive treatment agent and the paint can also form chemical bonds, which will couple the substrate surface with the UV coating, and further promote the formation of a high degree of adhesion between the UV paint and the substrate.
Post time: Jun-28-2022