What are the common problems of liquid silicone products?

Liquid silicone products, as an environmentally friendly, low-carbon, and green product, have been widely used in various fields such as medical, infant and toddler products, electronic products, etc. due to their excellent physical and chemical properties. However, liquid silicone products also encounter some common problems during production and use.

Firstly, one of the common issues with liquid silicone products is incomplete curing. This is usually caused by too low vulcanization temperature or too short vulcanization time. Liquid silicone is generally platinum vulcanized, with a vulcanization temperature generally between 110 ℃ and 150 ℃. Due to differences in the raw materials and product structure of liquid silicone, the vulcanization temperature may vary. If the mold temperature is too low, the liquid silicone gel will not be able to fully cure, resulting in insufficient product hardness, sticky surface, and other problems. The countermeasure is to detect the mold temperature and appropriately increase the mold temperature to the appropriate vulcanization temperature. Meanwhile, vulcanization time is also an important factor affecting the completeness of curing. The vulcanization time of liquid silicone gel is generally between 60S and 300S, and the specific time needs to be determined according to the silicone raw material and product structure. If the vulcanization time is too short, it can also lead to incomplete curing. The countermeasure is to appropriately extend the vulcanization time to ensure that the liquid silicone gel fully reacts.

In addition to temperature and time factors, incomplete solidification of liquid silicone products may also be related to pollution. For example, pollutants such as machine lubricating oil, rust proof oil on molds, and sweat and grease on workers’ hands can all damage the vulcanization structure of liquid silicone gel. These oily pollutants can adhere to molds or silicone raw materials, hindering the progress of vulcanization reactions. The countermeasure is to clean the injection pipeline and mold to keep them clean and pollution-free. At the same time, workers are required to wear finger cots or gloves during operation to prevent sweat, oil, and other pollutants from coming into contact with liquid silicone gel.

Special attention should also be paid to the mixing process of liquid silicone gel. Liquid silicone gel is a two-component mixture of A/B agents, and should be thoroughly mixed before vulcanization molding. If the mixture is uneven, white transparent tiny gel particles will appear in the product, which will affect the appearance and performance of the product. The countermeasure is to use the mixing system of the brand manufacturer as much as possible, adjust the speed and pressure of the mixer, and ensure that the liquid silicone is fully and evenly mixed. In addition, some companies may refrigerate and store pre mixed rubber materials to extend their shelf life when temporarily not in production. However, when using refrigerated adhesive materials again, they need to be left at room temperature for a period of time to recover to the appropriate temperature and viscosity before use, otherwise it will also affect the curing effect.

Liquid silicone products may also encounter the problem of low embedded material temperature during the production process. This is mainly aimed at adhesive products, especially those with thicker embedded layers. If the temperature in the workshop is too low (such as in winter), the temperature of the embedded materials (such as plastic or hardware) will also decrease, causing the liquid silicone to be unable to bond tightly with the embedded materials during the vulcanization process. The countermeasure is to preheat the embedded object to a suitable temperature before vulcanization.

The selection and use of release agents are also important factors affecting the quality of liquid silicone products. There are many types of liquid silicone, and the performance of different types of silicone may vary, as well as the release agent used. If the release agent is selected improperly or used incorrectly, it can lead to difficulties in demolding the product, scratches or damage on the surface, and other issues. The countermeasure is to choose the appropriate release agent based on the silicone model and manufacturer’s recommendation, and use it according to the correct method. At the same time, the surface of the mold also needs to be kept clean and free of pollution to avoid the influence of oil and grease pollutants on the demolding effect.

During the production process of liquid silicone products, bubble problems may also occur. The generation of bubbles is usually caused by factors such as the mixing device not being locked, uneven mixing of the rubber material, or unreasonable design of the injection port. The presence of bubbles can affect the appearance and performance of products, and even lead to product scrapping. The countermeasure is to check whether the mixer is locked tightly to ensure even mixing of the rubber material; At the same time, design the injection port and exhaust structure reasonably to avoid the generation of bubbles. For products that have already produced bubbles, repair or re production methods can be used for treatment.

Liquid silicone products may also experience deformation or shrinkage during use. This is mainly due to the low deformation temperature of the embedded object, uneven stress distribution, or inconsistent shrinkage rate of the silicone gel with the embedded object. The countermeasure is to replace the raw materials of embedded objects and use high-temperature resistant materials; Adjust the force bearing parts of the embedded object to achieve balanced force distribution; At the same time, it is recommended that customers modify the structure of liquid silicone products to make the structure of the silicone part uniform and avoid local thickness or thinness. In addition, adjusting the injection amount and increasing the injection pressure can effectively avoid shrinkage problems.

Liquid silicone products may also experience poor adhesion during use. This is mainly due to dirty embedded objects, improper selection of adhesives, or chemical reactions between release agents and adhesives. The countermeasure is to clean and dry the embedded objects before molding; Replace the appropriate adhesive; At the same time, try not to use or minimize the use of release agents. If it is necessary to use release agents, they should be sprayed for half an hour before production to avoid chemical reactions. In addition, surface treatment of the mold can also improve the demolding effect and enhance the bonding quality.

In summary, liquid silicone products encounter various common problems during production and use, including incomplete curing, contamination, uneven mixing, low temperature of embedded materials, improper selection of release agents, bubble problems, deformation or shrinkage, and poor adhesion. We can take corresponding measures to solve these problems, such as adjusting the vulcanization temperature and time, cleaning the mold and injection pipeline, fully mixing the rubber material, preheating the embedded objects, selecting suitable release agents and adhesives, designing the injection port and exhaust structure reasonably, and adjusting the product structure and injection amount.