Release Agent

Jun 4, 2020

The release agent is to prevent the molded composite product from sticking to the mold, and a type of isolation film is applied between the product and the mold so that the product can be easily released from the mold, while ensuring the surface quality of the product and the mold intact. The release agent is divided into two types: internal lubricity and external lubricity. The former is mainly to improve the lubricity of the polymer molecule itself, which requires a certain degree of affinity or compatibility with the resin polymer. The latter is to improve the lubricity between the mold and the polymer.
Interpretation: to ensure that the surface quality of the product and the mold are intact
Properties: Improve the lubricity between the mold and the polymer
Advantages: can be used at a temperature of about 180 ℃
Commonly used release agents mainly include the following categories:
(1) There are external release agent and internal release agent according to the usage of the release agent. The external release agent directly coats the release agent on the mold; the internal release agent is a compound with a melting point slightly lower than the ordinary molding temperature. It is added to the resin in the heat forming process and it is compatible with the liquid resin However, it is incompatible with the cured resin. Under certain processing temperature conditions, it oozes from the resin matrix and forms a layer of separation film between the mold and the product.
(2) According to the state of the release agent, there are film type (mainly polyester, polyethylene, polyvinyl chloride, cellophane, fluoroplastic film), and solution type (mainly hydrocarbons, alcohols, carboxylic acids and carboxylic acid esters) , Metal salts of carboxylic acids, ketones, amides and halogenated hydrocarbons), paste and wax (including silicone ester, HK-50 heat-resistant grease, cylinder oil, gasoline and asphalt solution and wax type) release agent. The wax release agent in the base is the most widely used type of release agent. It is cheap, easy to use, non-toxic, and has a good demolding effect. The disadvantage is that the surface of the product will be stained with oil, which will affect the surface paint. Make demoulding difficult. For large-scale products with complex shapes, it is often used in combination with solution-type release agents.
(3) According to the combination of release agent, there are single-type and compound-type release agent (including component compounding and compounding in use mode).
(4) According to the use temperature of the release agent, there are room temperature and high temperature release agents, such as room temperature wax, high temperature wax and stearates.
(5) According to its chemical composition, there are inorganic release agent (such as talc, kaolin, etc.) and organic release agent.
(6) There are one-time release agents and multiple release agents according to their multiplexing times.


Due to the excellent adhesion of epoxy resin to other materials, the mold release agent will be encountered when the mold is used to mold the epoxy resin. In order to remove the cured product from the mold smoothly, a mold release agent must be applied on the working surface of the mold. On the one hand, it can make the surface of epoxy resin products smooth, on the other hand, protect the mold from damage.


Therefore, the selection of it is very important. The general requirements for the release agent are as follows: easy to use, short drying time; safe and non-toxic operation; uniform and smooth, good film formation; no corrosion to the mold, no effect on resin curing; The adhesion is low; it is easy to prepare and cheap.


In fact, it is difficult to fully meet the above requirements, and can only be selected according to the specific circumstances and conditions. Commonly used external lubricity release agents are as follows:


1. Films: such as polyethylene, polypropylene, polyvinyl chloride, polyester film and other plastic films. This plastic film release agent is easy to use and has good anti-sticking properties. But the disadvantage is that the laying is poor, and it is generally used for products with simple geometric shapes.


2. Solutions: Commonly used are polyvinyl alcohol, silicone oil, silicone grease, liquid or emulsified paraffin. For example, the release agent made of silicone grease and toluene solution has good film formation and good mold release effect, and can be used at a temperature of about 180 ℃. The disadvantage is that the mold should be baked at about 200℃ after being coated with silicon ester solution, otherwise it is not easy to form a film. Generally used for high temperature forming metal molds. There is also spraying suspended polytetrafluoroethylene or polyperfluoroethylene propylene on the metal mold, but this method is expensive and requires sintering.


3. Ointment, paraffin, stearic acid: but it is inconvenient to use and difficult to apply evenly, which affects the effect of stripping. It is divided into four categories: molded products after the wax is directly melted; emulsified products; molded products after being blended with other substances; and finished products after chemical reaction.