Defoamer is a substance with low surface tension and high surface activity, which can inhibit and eliminate foam in the liquid, that is to say, defoamer can reduce the surface tension of water, solution, suspension, etc., to prevent foam generation or eliminate the original foam.Long-term defoaming is also known as defoaming, and the length of the defoaming time is the main sign of the quality of the defoaming agent. In most cases, the use of defoamer is to take advantage of its foam inhibition properties, rather than the initial defoamer.Defoaming and defoaming are relative, and the relative defoaming performance of products with good defoaming performance will be worse. In practical applications, it depends on the specific situation. Therefore, from the perspective of defoaming effect, defoaming agents include defoaming agents, defoaming agents and defoaming agents, which are collectively called defoaming agents.

Some components of water-based adhesives are easy to produce bubbles, and have a tendency to be stable and durable. In addition, rapid mixing in production and high-speed brushing construction in use will also contribute to foam generation, so that production can not proceed normally, and affect product quality. The formation of foam to the production and coating tape to great difficulty, and make the rubber layer appear pores, affect the product outside and adhesive properties, so we must try to destroy the foam or prevent the production of foam, the most effective way is to use defoaming agent.

There are many varieties of defoamer used in the water-based adhesive industry, but it mainly consists of two categories: polysiloxane defoamer and non-siloxane defoamer.

Polysiloxane defoamer has strong defoaming and anti-foaming ability and is widely used in the coating industry. In the water-based adhesive industry, especially the emulsion type low viscosity system, such as film adhesive, pressure sensitive adhesive, etc., it is very easy to cause shrinkage and fisheye problems. In addition, after the emulsion film formation, due to the surface migration of silane, it will cause the later bonding strength to decline, affecting the bonding effect, so it is generally rarely used.

Polysiloxane defoamer has strong defoaming and anti-foaming ability and is widely used in the coating industry. In the water-based adhesive industry, especially the emulsion type low viscosity system, such as film adhesive, pressure sensitive adhesive, etc., it is very easy to cause shrinkage and fisheye problems. In addition, after the emulsion film formation, due to the surface migration of silane, it will cause the later bonding strength to decline, affecting the bonding effect, so it is generally rarely used.

In the water-based pressure sensitive adhesive and film adhesive industry, mineral oil defoamer is generally used. It is mainly composed of mineral oil, hydrophobic particles, low carbon alcohols, emulsifiers and so on. The quality of this kind of product is easily affected by the brand and batch difference of mineral oil. Since the whole system is thermodynamically unstable, it is easy to stratify and provide defoaming effect mainly by dispersing in the emulsion. Affected by small molecular additives and surfactants in the emulsion, mineral oil defoaming agent is easy to slick oil in these systems, which will cause a serious decrease in the defoaming effect. The uneven distribution of mineral oil will also affect the coating effect, which brings great trouble to our production and application.