UV spray defoamer: which links to blistering can be solved
UV paint is a transparent coating, the role is to spray or roll coating on the surface of the substrate after the UV light irradiation to promote the decomposition of the initiator, the generation of free radicals, triggering the resin reaction instantaneous curing into a film, in order to play a protective primer and decorative role. However, in the process of UV spraying, if no UV spraying defoamer is used, sometimes there are phenomena such as surface blistering, resulting in an uneven surface of the substrate, and fillers and dyes are not adequately wetted. Longchang Chemical will share with you today the reasons for this:
1. spraying production environment of high humidity: when the UV spraying environment humidity is higher than eighty percent, the primer in the drying process will absorb a certain amount of moisture, coupled with insufficient baking time, UV curing in the storage process will release certain gases and substances.
2. affected by external forces: UV in the air when spraying, the paint within the turbulence, splash, impact, gas nest, etc., will add to varying degrees the free energy of the paint system, resulting in the generation and accumulation of foam.
3. paint out of the problem: the use of UV cost less, these paints in the addition of additives when the ratio is not reasonable, easy to appear bubbles and other problems.
For a variety of UV spraying when the above blistering situation, we can use a number of solutions, in addition to control the environmental humidity, keep between twenty-five and eighty percent, pay attention to debugging the proportion of paint blending, you can also add the right amount of UV spraying defoamer, the defoaming and foam suppression together to arrange the work in place. The specific reasons are as follows:
1. the main components of the UV spraying defoamer has a very strong anti-foaming properties. It is mainly made of organic polyether resin, mineral oil, alcohol compound, with self-emulsifying, easy to disperse, universal strong characteristics.
2. UV spray defoamer has fast defoaming speed and long foam inhibition time, and has good effect on micro-fine foam and all kinds of stubborn foam. And UV spray defoamer additive is also very small, only the total amount of 0.001-0.008 between, you can reduce a lot of costs for the enterprise, improve the efficiency of construction.
3. with UV spray defoamer effect is good at the same time, but also do not worry about it will bring other bad effects on the paint, such as the inability to dissolve with the paint well, the appearance of spraying the surface of the substrate uneven, affecting the film properties and other phenomena.
Defoamer for coatings is a compound defoamer made of ether, fat, alcohol and other substances through a special process. Coating defoamer in the water-based system dispersion, has a strong self-emulsification, good defoaming, long-lasting foam inhibition characteristics, especially for water-soluble polymers and low and high viscosity system has a special effect. It is also effective in eliminating large and fine foam in emulsions, with long-lasting foam inhibition and good compatibility and dispersibility.
The defoamer for paints has a special effect on the foam produced by acrylate/polyurethane and polyurethane, and has the characteristics of low dosage, long foam inhibition and good water dispersibility for micro-foam. This defoamer for emulsion paints is added at the high-speed dispersion and grinding stage to inhibit bubble generation and eliminate foam.
Application notes on defoamer for paints are explained as follows:
1、Operate in strict accordance with industrial health and safety practices.
2. Do not pour waste down the drain.
3、Do not eat, drink or smoke when using the product.
4、After using the product, you need to wash your hands with mild soap and water.
The choice of defoamer should be in accordance with the following points:
1. Insoluble or insoluble in foaming solution
To break the foam, the defoamer should be concentrated and concentrated on the bubble film. In case of defoamer, it should be concentrated immediately, and in case of defoamer inhibition, it should always be kept in this state. Therefore, the defoamer is supersaturated in the foaming solution and only insoluble or insoluble is susceptible to supersaturation. Insoluble or insoluble, easy to gather at the gas-liquid interface, easy to concentrate on the bubble film, at a lower concentration can work. For the defoamer used in the water system, the molecules of the active ingredients must be strongly hydrophobic and weakly hydrophilic, HLB value in the range of 1.5-3, the effect * good.
2、Surface tension is lower than foaming liquid
Only when the intermolecular force of the defoamer is small and the surface tension is lower than the surface tension of the foaming liquid, the defoamer particles can be submerged and swollen in the foaming film. It is worth noting that the surface tension of the foaming solution is not the surface tension of the solution, but the surface tension of the foaming solution.
3, and foaming solution has a certain affinity
As the defoaming process is actually a competition between the rate of foam collapse and the rate of foam formation, the defoamer must be able to disperse quickly in the foam solution in order to play a role in various foam solutions. The active component of the defoamer must have a certain affinity for the foaming liquid in order to enable the defoamer to diffuse rapidly. The active component of the defoamer is too close to the foaming liquid and will dissolve; too thin and difficult to disperse. Only familiarity is appropriate, the effect will be good.
4、No chemical reaction with foaming liquid
Defoamer and foaming liquid reaction, on the one hand, defoamer will lose its role, on the other hand, may produce harmful substances, affecting the growth of microorganisms.
5、Low volatility, long action time