Why use silicone mold-release agents in plastic processing?

The release agent is a special type of lubricant that prevents polymers from adhering to molds during processing. There are many types of release agents, most of which are substances with low surface tension that form a continuous anti-adhesive film between the polymer and the mold and can be divided into short-life and semi-permanent releases according to their mode of action. Why choose silicone mold release agent in plastics processing?

Silicone mold release agent has a certain degree of thermal stability and does not corrode the mold, it is chemically inert, does not react with the components in the resin, and has no residual decomposition properties. In the production process of plastic products, the use of silicone mold release agents can effectively improve product yield and avoid unnecessary losses.

The following seven aspects of silicone mold release agent how to play a role in plastic processing:

1. What is a mold release agent?

A mold release agent is an interfacial coating used on the surface of two objects that are easy to adhere to each other, making the surface easy to detach, smooth, and clean when mold making. Mold release agents are used in a wide variety of molding operations such as fiberglass reinforced plastics, metal die casting, polyurethane foams and elastomers, injection molded thermoplastics, vacuum foamed sheets, and extruded profiles. In molding, sometimes other plastic fillers such as plasticizers bleed out onto the interface and need a surface release agent to get rid of it.

Most of the release agents are mineral oils or Polysiloxanes (silicone oils) that form a thin film between the mold and the workpiece. Because the release agents are very low-tension inert substances that do not bond to either the mold or the workpiece, the workpiece can be easily removed from the mold when mold making. In the general forging mold process the concentration value of the release agent is relatively strict, usually the ratio of 100:1 ratio of the aqueous solution, diluted concentration value range is 0.16% -0.40%. The concentration of the release agent can directly determine the surface quality of the workpiece in the process of demolding, but also ensure that the surface of the mold itself will not be damaged in the process of demolding, to ensure the service life of the mold.

2. What kinds of mold release agents?

(1) Silicone system: Dimethicone, Alkyl silicone oil, Alkyl square silicone oil, hydrogenated silicone oil, hydroxyl silicone oil, amino silicone oil, Methyl silicone resin, Methyl Phenyl silicone oil, silicone dispersions.

Features: Multiple demolding, high-temperature resistance, abrasion resistance.

(2) Mineral oil, grease/wax/hydrocarbon solvent oil system: mineral oil, synthetic oil, paraffin wax, microcrystalline wax, polyethylene wax, oxidized polyethylene wax, modified polypropylene wax, carnauba wax, animal wax, solvents, grease.

Features: Good paintability

(3) Fluorine system: Fluorine-containing surface active, fluorine-containing polymers

Features: Good mold release and continuity, non-transferring

(4) Powder system: Talc, mica, bentonite, boron nitride, diatomaceous earth, graphite, molybdenum disulfide quartz powder

Features: High-temperature resistance, wear-resistant, and anti-stretching

(5) Surfactant system: Fatty acid soap (potassium soap, sodium soap, calcium soap, magnesium soap, zinc soap, etc.), Polyether/Polyester

Features: Easy cleaning agent

(6) Composite system: Silicone + wax, silicone + fluorine system, surfactant + powder system

Features: Good overall performance

3. How to choose the mold release agent?

Factors to be considered when selecting mold release agents:

(1) Performance of mold release agent

The mold release agent should have good mold release; heat resistance, not due to heat and carbonization decomposition; chemical stability, not react with the molding material; film thin and effective: not easy to mix with the molding material and other properties.

(2) Carrier of mold release agent

The carrier of the release agent (dispersant) and the components of the release agent have good compatibility, and play a dispersing role: high volatility; it does not corrode metal molds, safe, low toxicity (or non-toxicity); it is non-combustible, non-flash point, non-explosive; it is inert for the processing of plastics.

Mold release agent mold release effect is affected by both chemical operations, but also by physical conditions, molding raw materials and processing conditions are different, and the best varieties of selected release agents and dosage must be integrated into the conditions based on the specific circumstances to determine.

Plastic mold release agents are mostly silicone systems, generally sprayed can-type silicone dilution is widely used.

4. What is the silicone mold release agent?

Used as a release agent for silicone compounds for silicone, commonly silicone oil, silicone rubber, and emulsified silicone oil.

(1) Silicone oil

Silicone oil and filler are mixed together to make a paste, which can be applied on the vertical surface. For best results, this method is suitable for the mold and is not too complex for pressure casting. Commonly used types are Methyl silicone oil, emulsified silicone oil, Methyl hydrogenated silicone oil, and Ethyl silicone oil.

XJY-701 Polymethylhydrosiloxane is a high molecular weight organic synthetic with a universal chemical structure, it is a kind of high-hydrogen silicone oil, which can form a thin layer and be used as one of the raw materials of mold release agent. It can determine whether it is suitable for the customer.

XJY-702 Methylhydrosiloxane/Dimethylsiloxane Copolymer is non-toxic and tasteless, with active genes, which can react with a double bond, hydroxyl, and other groups under the action of catalyst, and it is the basic raw material of polyether-modified silicone oil, which can be used as one of the raw materials of mold releasing agent, and start molding immediately.

(2) Silicone rubber

Silicone rubber can be used to dissolve silicone rubber in organic solvents, and then coat in the film, the solvent evaporates after the formation of a layer of silicone rubber film, this layer of film can be vulcanized, but also not vulcanized. The not vulcanized film is actually a layer of extremely high viscosity silicone oil film, this film has a very good release effect but also can be repeated coating. Another room-temperature vulcanized silicone rubber can be made into molds in the curing process, casting epoxy resin with a permanent mold release effect.

(3) Silicone grease

It is intentional substances made of silicone oil and fumed silica by mixing and processing, there is a great thixotropy, that can be wiped directly on the mold coated to achieve the effect of mold release.

(4) Silicone resin

The main function of silicone resin mold release agents is to provide an excellent mold release effect. The silicone element in its molecular structure can form a very thin and uniform isolation film with the surface of the mold, which effectively reduces the friction coefficient between the material and the mold, making it easier to release the products, and reducing the breakage and deformation of the products.

XJY-RA/XJY-RAN MQ Silicone Resin is made of tetrafunctional organosilicon (Q) and monofunctional methyl organosilicon (M) polymerization, in the field of high-temperature, semi-permanent, and permanent mold release agent has good application efficacy. Silicone mold release agents are specially formulated to be resistant to high and low temperatures, have low surface tension, and are non-corrosive to metals. The addition of silicone resin (5-15%) can significantly improve the strength of silicone oil film, in the field of high-temperature castings and other areas with good application efficiency.

5. What mold-releasing agent should be chosen for plastic processing?

The mold release agent is required not to affect the color of products and post-processing, good cleaning, easy to form excellent mold release, no pollution of the environment, and other properties.

Compared with the traditional mold releases agent, silicone mold release agent has selective adhesion ability, and can be preferred to adhere to the mold without passing to the molded parts at the same time, it can also play a role in modifying the surface of the resin, which is conducive to resin mobility, improve the surface quality of molded parts.

Because of processing and molding in the plastic melt and mold surface contact, it often forms a chemical bond on their surfaces, it also forms negative pressure on the surface of the two objects, so there is plastic molding products are difficult to disengage, or almost can not be disengaged from the situation. At this time, it is necessary to use a thin layer of efficient diaphragm release agent, to prevent the occurrence of adhesion, in order to facilitate the release of products. In industrial production, some plastics, such as aldehydes, epoxy, polyester, high-pressure polyethylene, and other molding are difficult to release, the use of traditional paraffin wax, and silicone oil, often can not meet the requirements, especially in the unsaturated polyester, epoxy resin molding process, the application of silicone mold releasing agent selection has become indispensable and important content.

6. What are the precautions for the use of silicone mold release agent?

(1) The oil-based release agent is easy to brush, mold release effect is also good, but the surface of the structural components has a certain degree of pollution, affecting the decorative decoration, and therefore should be used with caution. One of them is emulsified machine oil, when used according to the emulsified machine oil: water = 1:5 deployment (volume ratio), stirring evenly after brushing, the effect is better. Oil mold release agents can be used at low and negative temperatures.

(2) Methyl silicone resin is transparent, hard, wear-resistant, heat-resistant, and water-resistant after curing. Coated on the steel mold surface, not only plays a role in isolation but also in rust prevention and protection. The material is non-toxic and can be sprayed or brushed.

(3) Containers and tools should be clean and free of rust and corrosion, and should not be mixed with impurities. After the tool is used, it should be cleaned and dried with alcohol. Due to the addition of ethanol money easy to cure, should not be more than matching. Therefore, it should be prepared according to the dosage. With the phenomenon of thickening or gumming should stop using.

(4) Methyl silicone resin will accelerate polymerization in contact with light, heat, air, and other substances, it should be stored in a light, cool place, it must be covered tightly to prevent moisture from entering the storage period should not exceed three months.

(5) Before the first painting of methyl silicone resin mold release agent, the board surface should be thoroughly scrubbed clean, polished to a metallic luster, wiped off floating rust, and then scrubbed with cotton gauze dipped in alcohol. The cleaner the surface of the plate is, the stronger the mold is and the more times it is used in turnover.

(6) Adopting a Methyl silicone resin mold release agent, the surface of the template is not allowed to brush antirust paint. When the steel mold re-brush release agent and the board surface is wet, use a flat shovel, brown brush, or cotton wool to clean up slag, otherwise, dry cleanup will be more difficult.

(7) Brush mold release agent can be sprayed or brushed, the operation should be rapid. After the film, we do not brush back to avoid gumming. The coating should be thin and even, too thick but easy to peel off.

(8) In addition, the use of a mold release agent should pay attention to the coating uniformity, with a high concentration of sub-coating, rather than a low concentration of 23 times, which can improve the release of the mold; The concentration of the release agent should be appropriate, too high will make the gas stagnation; In the dilution of water-type release agent, the need for ion-exchanged water or potable water, it can not be used with hard water; It need to regularly remove deterioration of the mold release agent and contaminants, etc.

7. How to make silicone mold release agent performance better?

The purpose of using a silicone mold release agent is to reduce the adhesion between the surface of the plastic part and the surface of the mold cavity, its thin layer prevents them from sticking to each other, so as to shorten the molding cycle and improve the surface quality of the plastic part. How to improve the competitiveness of your products and determine suitability?

XJY Silicones is one of the leading silicone MQ resin and VMQ silicone manufacturers in China, with more than 30 years of R&D and manufacturing experience in the silicone industry as well as more than 15 related patents and technical support. Our silicone raw material products can meet the needs of the release agent field and support the provision of diversified customized solutions.