According to the types of effective release substances in water-based release agents, they are mainly divided into silicone oil type, wax type, etc.
1. Silicone oil water-based release agent
Silicone oil and its derivatives are more suitable as polyurethane release agents, as they have good release properties. For example, a release agent for aluminum alloy molding and casting is composed of silicone oil, special pressure lubricant, emulsifier, and water. Over the years, it has been proven that silicone oil and its derivatives have good demolding effects. But when molded products need to undergo secondary processing, such as post coating, silicone oil release agents have certain side effects.
2. Wax based water-based release agent
The release agent used in polyurethane molded products is mainly wax, which has good demolding properties. In the early days, wax was added to organic solvents to make mold release agents. Recently, it has been reported that wax can be added to water to make a suspension water-based mold release agent. The wax used is natural wax or artificially synthesized wax such as polyethylene wax. This kind of release agent is mainly used in the production of soft foam.
3. Fatty acid water-based release agent
The components of this type of release agent include higher fatty acid esters, fatty acid salts, other additives, and water. It is used for the production of hard and soft foam molded products.
Composition of water-based release agent
Generally speaking, water-based release agents consist of at least three components: base material, emulsifier, and water. Basic materials can be considered as effective ingredients, ultimately exerting a lubricating effect on demolding. The materials used are generally oil, grease, wax, polymers, and silicone based substances. The function of the emulsifier is to uniformly disperse the above materials in the continuous aqueous phase in extremely fine particles to form a stable lotion. Water is only used as a carrier. The main components of water-based release agents made by emulsifying refined oil and various additives are mineral oil, animal and vegetable oil, synthetic oil, natural paraffin, synthetic paraffin, silicone oil, solid (lubricating oil), emulsifier, additive, mold inhibitor, and rust inhibitor. High quality release agents are mostly formulated from 15 to 25 types of raw materials, and if the key components or additives are changed by 1%, their release properties may vary greatly, which will also bring significant changes to costs and prices. Each type of release agent has its optimal application range and target audience. If the wrong target audience is used, even the highest quality product cannot exert its effectiveness. Water based release agents generally do not contain solid particles. When used, they can be diluted with water by tens to hundreds of times, and the water content generally accounts for more than 95%.
Due to the abundant presence of water, there are many differences between traditional oil-based or solvent based release agents. The demolding effect of water-based release agents depends on the deposition of a thin film with a thickness of only micrometers on the surface of the mold cavity after spraying. Therefore, there are higher requirements for ingredient selection and usage processes. But its advantages are also obvious, such as facilitating automated operation, good cooling effect, no accumulation, improved surface quality of castings, reduced internal porosity, safe use, clean production, and reduced environmental pollution. Based on this, some people believe that the evolution of water-based release agents is a significant change in the development history of die-casting release agents.
