Introduction to Siloxane Release Agent - Part 1

Food Baking – One of Applications of Siloxane Release Agent

 Cited from: https://pixabay.com/zh/photos/cookie-bake-pastry-pastries-sweet-756601/

Cover Photo cited from: https://pixabay.com/zh/photos/bakery-bread-baker-apron-baking-1868396/

Besides the silicone greases, silicone ointments and silicone oil defoamer, siloxane release agent is another type of product which is derived from silicone oil. The main function of siloxane release agent is to curb or to reduce the mechanical damage from the mature product is being collected from mould. The ideal adhesive film agents should contain the following properties:

1.      It has excellent demoulding capacity;

2.      The chemical should not have corrosion and deposition on moulds;

3.      The chemical should be easy to flow and will not leave blanks;

4.      The surface of the product should be clean and plain;

5.      The chemical will not influence the further processing procedures;

6.      The chemical is easy to be diluted stable;

7.      The dilution has inertia and hard to be inflamed and volatized;

8.      The cost is low;

9.      The consuming amount is low;

10.  The disposable coating could be used for multiple times.

Silicone oil has excellent properties like low surface tension, excellent heating resistance and low solubility parameters. Thus, it is an ideal release agent material, and it has been applied as release agent for a long time. To compare with common organic release agents, it has many advantages like silicone oil is easier to flow to the surface of moulds to make films; the consumption amount is small and one coating could be used for many times; it could be used as release agent for many materials and will keep the products and moulds clean; there is no need to clean the moulds frequently and reduce the numbers of procedures and corresponding operation times; it has good adhesive resistance and lubricity to most macromolecular materials; it will not have corrosion on moulds and products; the flashing point is high and it is not poisoned or smelly; the inertia allows the products to be the release agents of food package materials and food baking. Silicone oil release agent could also be used in moulding, sealing and coating. At present, it is used more in shaping, rubber processing, printing and coating, especially in the shaping of tires. Even though the average manufacturing cost of silicone oil release agent is higher than general release agent, but it is due to the low consumption amount, the total cost of using silicone oil release agent is still economical. Also, the silicone oil release agent will not produce smoke or smells during usage, thus it is more popular.

The half-permanent release agent which is made from silicone resins could reduce the coating frequencies and the surface processing time to reduce the whole moulding time. High-viscosity silicone oil which is used as the additive to the thermo plasticity resins will help to reduce the manufacturing periods and reduce the waste rate and other damages. However, this application is gradually being altered by crosslinking siloxane.

Categories of Siloxane Release Agent

The basic polymers which are suitable to make siloxane release agent are mainly non-crosslinking silicone oil, crosslinking silicone oil and silicone resins. They could be directly used as release agents or being one the materials to other release agents. Thus, they could be divided to 6 types of products.

The first type is the pure silicone oil. When the demoulding system will not contact water, organic solvents and emulsion, it is common to use silicone oil as release agents by coating it by cloth. The suitable materials are dimethyl silicone oil, methyl phenyl silicone oil, hydroxyl silicone oil and others.

The second type is the solvent release agent. It is usual to allow the silicone oil and additives to be soluble to organic solvents to get 5% ~ 50% products.

The third type is the emulsion release agent. Sometimes the pure silicone oil release agent is not convenient and the demoulding effect is not satisfied. By using solvent release agent, there is possibility to be inflamed or to be poisoned. It is according to these situations, the emulsion release agent comes out and soon it becomes today’s main product. In emulsion products, some of them are to reduce the consumption amount by adding organic solvents to volatize faster.

The forth is the silicone ointment type. It is to put some silica powder to silicone oil to get white half-transparent ointment products. The thermal oxidation stability and demoulding durability is better than oil type, solvent type and emulsion type. It could last over 1 hour in 300℃ air. It is more applied in shaping demoulding of high temperature and high pressure or anti-adhesion.

The fifth is the spray type. It is actually one subcategory of the solvent type; it is made of silicone oil and its additives to be mixed with organic solvents in the form of air under room temperature to be put in the spray bottles which have pressures.

The last type is the solidification type. All of the other five types’ main effective components are non-crosslinking silicone out but the one of solidification type is the crosslinking siloxane.

The silicone resin release agents are usually to put low silicone resin polymers which have condensate functional groups with low R / Si ratio, silicone oil, curing agent and thickeners to solute to mixed solvents. This type of release agent is widely used in food baking. To compare with silicone oil release agent, silicone resin agent has the advantages like:

1.      The coating cloth could be used for tens or even hundreds of times to reduce the material cost and human cost;

2.      It could increase the productivity of equipment;

3.      It could reduce the waste rate;

4.      I t could keep the surface of product clean;

5.      There will be hardly smokes;

6.      It could extend the product life of moulds.

Summary

We could see clearly that there are many types of siloxane release agents and each of them has their own unique properties and applied industries. The applications could be from food baking to some very advanced engineering fields.

In the next article, we are continuing to introduce about the siloxane release agents.