What causes white spots on silicone coated products?

During the production and use of silicone coated products, white spots may sometimes appear, which not only affects the appearance quality of the product, but may also have a potential impact on its performance and service life.
1、 Sulfurization process issues
The vulcanization process of silicone encapsulated products is crucial in the production process. One of the main causes of white spots is incomplete vulcanization or improper vulcanization conditions.
1. Low vulcanization temperature: The vulcanization temperature of liquid silicone is generally between 110 ℃ and 150 ℃. Due to the different raw materials and product structures of silicone, the vulcanization temperature may vary slightly. If the vulcanization temperature is too low, the silicone gel will not fully cure, resulting in the formation of white spots on the surface. The countermeasure is to detect the mold temperature, ensure that the actual measured temperature meets the vulcanization requirements, and appropriately increase the mold temperature.

2. Short vulcanization time: The vulcanization time of liquid silicone is generally between 60 seconds and 300 seconds, and the specific time varies depending on the silicone raw material and product structure. Short vulcanization time can also lead to incomplete curing of silicone gel and the formation of white spots. The countermeasure is to extend the vulcanization time appropriately to ensure that the silicone gel is completely cured.
3. Excessive storage time of rubber material: After mixing silicone rubber with sulfur and color, if stored for too long, the vulcanizing agent in the rubber material may evaporate, resulting in incomplete vulcanization. The countermeasure is to reasonably control the storage time of the rubber material, avoid long-term storage, and regularly check the quality of the rubber material.
2、 Oil pollution
During the manufacturing and use process, pollutants such as grease and sweat may adhere to the surface of silicone or infiltrate the interior of silicone, leading to the formation of white spots.
1. Machine and mold pollution: Oil and grease pollutants such as machine lubricating oil and mold rust prevention oil can damage the sulfurized structure of silicone, leading to white spots. The countermeasure is to regularly clean the injection pipeline and mold to ensure cleanliness and no pollution.
2. Worker operation pollution: During the operation process, sweat and grease on the hands of workers may contaminate silicone gel. The countermeasure is to require workers to wear finger cots or gloves during operation to avoid direct contact with silicone.
3、 Moisture influence
Silicone products stored or used in humid environments may allow moisture to seep into the interior of the product, causing white spots.
1. Wet storage environment: Silicone products stored in a humid environment are prone to absorbing moisture from the air, leading to the formation of white spots inside. The countermeasure is to store silicone products in a dry and ventilated environment to avoid moisture.
2. Moisture during use: If silicone products are exposed to a humid environment for a long time during use, white spots will also appear. The countermeasure is to ensure a dry usage environment and avoid prolonged exposure to humid conditions.
4、 Chemical reaction
Silicone may undergo chemical reactions when in contact with certain chemicals such as alcohol, cleaning agents, etc., leading to white spots.
1. Improper use of cleaning agents: Using inappropriate cleaning agents to clean silicone products may result in white spots on the surface. The solution is to choose an appropriate cleaning agent, such as alcohol or detergent, and thoroughly air dry it after cleaning.
2. Chemical exposure: Silicone products may undergo chemical reactions when in contact with alcohol, cleaning agents, and other chemicals, leading to white spots. The countermeasure is to avoid contact between silicone products and these chemicals as much as possible, or to clean them immediately after contact.
5、 Material aging
Long term exposure to ultraviolet radiation or high temperature environments may cause silicone materials to age and develop white spots on the surface.
1. UV irradiation: Long term exposure of silicone products to UV radiation can accelerate material aging and cause white spots on the surface. The countermeasure is to use shading or insulation materials for protection to avoid prolonged exposure to ultraviolet radiation.
2. High temperature environment: Long term use of silicone products in high temperature environments can also accelerate material aging and lead to the formation of white spots. The countermeasure is to try to avoid using silicone products for a long time in high temperature environments, or to choose high temperature resistant silicone materials.
6、 Other factors
In addition to the above main reasons, there are also other factors that may cause white spots in silicone coated products.
1. Low temperature of embedded materials: For encapsulated products, especially those with thick embedded materials, if the workshop temperature is too low and the embedded material temperature is too low, it may cause incomplete vulcanization of silicone gel and produce white spots. The countermeasure is to preheat the embedded objects to ensure a suitable temperature during the vulcanization process.
2. Surface contamination of molds: The mold surface may be contaminated with grease during the production process, causing white spots to appear on silicone products during vulcanization. The countermeasure is to clean the mold with cleaning agents such as toluene to ensure that the mold surface is clean and free of pollution.
3. Uneven mixing: Liquid silicone needs to be thoroughly mixed before vulcanization molding. If the mixing is uneven, it may lead to incomplete vulcanization and the formation of white spots. The countermeasure is to use the mixing system of the brand manufacturer, adjust the speed and pressure of the mixer to ensure uniform mixing.
7、 Solution strategy
The following strategies can be adopted to address the causes of white spots in silicone coated products:
1. Strictly control the vulcanization conditions: ensure that the vulcanization temperature and time meet the requirements of the silicone raw material and product structure, and avoid incomplete vulcanization leading to white spots.
2. Strengthen cleaning and protection: Regularly clean and protect injection pipelines, molds, and worker operations to avoid contamination of silicone gel by pollutants such as grease and sweat.
3. Control storage and usage environment: Ensure that silicone products are stored and used in a dry and ventilated environment to avoid material aging caused by humidity and high temperature.
4. Choose the appropriate cleaning agent: Use the appropriate cleaning agent to clean silicone products, avoiding the use of inappropriate cleaning agents that may cause white spots on the surface.
5. Avoid chemical reactions: Try to avoid contact between silicone products and chemicals that may cause chemical reactions, or clean them immediately after contact.
6. Regular inspection and maintenance: Regularly inspect the quality and usage status of silicone products, promptly identify and address white spot issues, and ensure product performance and service life.
In summary, there are various reasons for the formation of white spots in silicone coated products, which require in-depth analysis and solutions from multiple perspectives such as vulcanization process, oil pollution, moisture influence, chemical reactions, and material aging. By strictly controlling the vulcanization conditions, strengthening cleaning and protection, controlling the storage and use environment, selecting appropriate cleaning agents, avoiding chemical reactions, and conducting regular inspections and maintenance, the problem of white spots in silicone encapsulated products can be effectively solved, improving product quality and service life.