What Is a Silicone Mold Release Agent?
A Silicone mold release agent is a chemical that allows products to be removed smoothly from molds during the molding process.
By applying silicone mold release agent to the mold, the product is prevented from sticking to the mold and can be molded beautifully without damaging the surface of the product. As the name suggests, silicone is used as the main ingredient.
Its low surface tension and ease of spreading make it easy to apply to any mold. Furthermore, it is chemically inert and can be used on almost any material. Their very low intermolecular forces and incompatibility with most molding materials make them excellent mold release agents.
Uses of Silicone Mold Release Agents
Silicone mold release agents are used in a variety of molding processes. They are useful for molding products made of various materials, such as plastic, rubber, and metal. For example, silicone mold release agents are used to cleanly mold plastic models, toys, car parts, kitchenware, and many other products found in our daily lives. Silicone mold release agents are also used in the food industry for molding food packaging and containers.
Other applications include die casting, surface treatment, and synthetic fibers. Silicone mold release agents can also be used for purposes other than improving mold release properties, as they also have functions such as glazing, surface protection, and lubrication. They are generally used in emulsion, oil, or solution form, but can also be baked or sprayed on.
Principle of Silicone Mold Release Agents
Silicones combine the properties of inorganic compounds based on Si-O bonds with those of compounds derived from organic groups such as methyl groups (-CH3) attached to Si atoms.
1. Mold-Releasing Properties
Silicones have low surface energy and low intermolecular forces because their surfaces are covered with organic groups. This means that they are less likely to stick to other substances and more likely to peel off. This property makes it possible to improve mold release properties.
When intermolecular forces are extremely low, cohesion is weak and diffusion is easy. Silicone can be spread thinly over the mold surface without becoming droplets. This results in the formation of an extremely thin silicone layer on the surface of the silicone mold release agent when it is applied to the mold. This silicone layer prevents direct contact between the product and the mold and facilitates demolding.
2. Heat Resistance
Silicone has high heat resistance and does not lose its functionality even at high temperatures. This is because the bond between silicon and oxygen, the main chain of silicone, is more stable than the bond between carbon and carbon. Therefore, silicone can be used in molds for plastics that are molded at high temperatures.
Although silicone may migrate to the surface of the molded product after demolding, it can be used for a long time by baking a silicone mold release agent into the mold to form a film.
Types of Silicone Mold Release Agents
1. Emulsion Type
An emulsion that has emulsified silicone oil, and it excels in dilution stability. They are used for food packaging containers, as release agents for rubber and plastic molding, ironing lubricants, and luster release agents.
2. Oil Type
It has excellent heat resistance and wettability, and is chemically inert. It is excellent for mold release and glazing in rubber, plastic and tire molding. It is also used as a base oil for other silicone mold release agents.
3. Solvent Type
Silicone resins are diluted with solvents such as toluene or other petroleum hydrocarbons. They have excellent wettability on molds. The solvent volatilizes easily, making heat treatment easy. When baked on, it forms a film that provides a long-lasting mold release effect and prevents transfer of the mold release agent to the product.
How to Choose a Silicone Mold Release Agent
This section explains how to select a silicone mold release agent. There are three main points to consider when selecting a silicone mold release agent.
1. Mold Release Performance
Whether or not a product can be demolded smoothly depends largely on the performance of the mold release agent. The appropriate mold release agent depends on the shape and material of the product, so it should be selected according to the purpose.
2. Heat Resistance
Select a mold release agent that can withstand molding temperatures. The required heat resistance varies depending on the material and molding method of the product to be molded.
3. Safety
It is important to select a mold release agent that will not affect the human body, especially when molding food or medical products.