Why do silicone products have bubbles? How to deal with it?

2023-11-29

Silicone products are used very frequently in life. Many things in our daily life may be made of silicone. Sometimes when we make silicone products, we will find that bubbles will appear on the surface or inside the silicone product. For Why do silicone products have bubbles? How to deal with bubbles in silicone products?

Note that this is very important for silicone product manufacturers to control the quality of the produced products. Silicone products with bubbles are very rough and not only look defective, but also feel bad to the touch. Jinyu Machinery professional will answer your questions below.

There are two raw materials for the production process of silicone products, one is liquid silicone and the other is solid silicone. Here we first talk about solid silicone.

1.Vulcanization temperature that is too low or vulcanization temperature that is too high is one of the main causes of bubbling in thermally conductive silicone products. The vulcanization temperature is an important parameter when molding silicone rubber. Usually silicone products are set at 160~200°C. However, sometimes due to the mold operating time being too long or other reasons, the mold has not been heated by the vulcanizer for a long time, resulting in The temperature of the silicone molding mold is low and the vulcanization temperature of the silicone is low, which will cause bubbles in the thermally conductive silicone product after molding. For this, we only need to increase the molding temperature, or put the empty mold into the machine and heat it for a period of time to solve the problem. If the vulcanization temperature is too high and the molding temperature is too high, it will also cause bubbles in thermally conductive silicone products. why? When the molding temperature is too high, the silicone raw material on the surface has begun to form during the mold closing and pressurization process. At this time, the air has been trapped inside and is difficult to discharge, so it will cause molding bubbles in thermally conductive silicone products. For this reason, the molding temperature only needs to be appropriately lowered.

2.The reason why silicone products have bubbles is insufficient exhaust. After the silicone raw material is placed in the mold, a lot of air will be brought in at the moment of mold closing. The air cannot be integrated with the silicone raw material. If the air is not discharged, , will cause bubbles to appear on the surface of the silicone button after it is formed.

3.The unreasonable structure of the mold and the unreasonable design of the silicone molding mold will also cause bubbles in the silicone molding. For example, the arrangement of the products in the mold, the partitioning method, the mold parting method, the design of the mold size, etc. will all cause poor bubbles, but when the mold is opened, it will cause bubbles. The cost of a set of molds is very high, and it is not easy to modify. If silicone molding bubbles are caused by the structure of the mold, then the solution is usually based on the points mentioned above.

4.The vulcanization time is too short. Like the vulcanization temperature, the vulcanization time is also one of the important parameters for the molding of thermally conductive silicone products. The length of the vulcanization time determines whether the thermally conductive silicone product can be completely vulcanized. If the vulcanization time is too short, not only will the thermally conductive silicone product become soft after molding, but it will also easily cause bubbles to form on the surface of the thermally conductive silicone product. If such defects occur, the vulcanization time of the silicone can be appropriately extended.

5.The production process is also very important: the anti-aging agent RD is prone to bubbles during the mixing operation of the open mill. This is mainly due to the high melting point of the anti-aging agent RD and the low operating temperature of the open mill. Regarding the mixing of the rubber compound, Special attention should also be paid to the dispersion of zinc oxide. Its uniform dispersion will also cause foaming of thermally conductive silicone products, so the rubber mixing process is also a very important link.

6.There are also the moisture content of the raw materials used in the formula and the adequacy of drying after the rubber mixing operation and products are extruded and cooled with water. This is mainly caused by the evaporation of water during the addition of sulfur.

Jinyu Machinery provides you with a vacuum vulcanizing machine, which has a vacuum function that can discharge gas during silicone vulcanization and molding. In addition, Jinyu Machinery also has silicone vacuum machines, silicone rubber mixing machines, silicone hydraulic presses machines, etc. Jinyu Machinery provide you the whole set of Silicone Machines, please feel free to contact with us.

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