In order to prevent the fogging of liquid silicone products, comprehensive optimization is required from multiple aspects such as material selection, process control, environmental management, mold and equipment maintenance, etc. The following are specific measures:
1. Material selection and pretreatment
Select high-quality silicone materials
Select liquid silicone that meets industry standards (such as food grade, medical grade) to ensure that the material is free of impurities and has not expired, and avoid incomplete curing due to quality problems of the material itself.
Preferably use silicone formulas with good anti-fogging performance, or adjust the hardness, viscosity and other parameters of silicone according to product requirements.
Strictly check the curing agent
Ensure that the curing agent matches the silicone material to avoid using expired or damp curing agents.
Add curing agent strictly according to the ratio provided by the supplier to avoid excessive or insufficient amounts.
Material pretreatment
Silicone materials and curing agents should be fully stirred before use to avoid uneven local concentrations.
For materials that are easy to absorb moisture, they need to be stored in a dry environment and dehumidified before use.
2. Process control and operating specifications
Optimize the mixing process
Use mechanical mixing equipment to ensure that the silicone and curing agent are fully mixed, and the mixing time is adjusted according to the material characteristics (usually 3-5 minutes).
Avoid the introduction of air during the mixing process to prevent bubbles from causing uneven curing.
Precisely control the curing temperature and time
Temperature control: The most suitable temperature for silicone curing is usually 20℃-30℃, and the operating environment temperature needs to be kept stable.
Too low temperature: slow curing speed may lead to incomplete curing.
Too high temperature: may accelerate curing, but it is easy to produce internal stress or surface defects.
Time control: According to the curing characteristics of silicone, set a reasonable curing time to avoid premature demolding or insufficient curing.
Vacuum degassing treatment
Vacuum degass the silicone mixture before infusion to remove bubbles and prevent atomization or pores on the surface after curing.
3. Environment and equipment management
Control the humidity of the operating environment
For silicone materials that need to be cured in contact with moisture, ensure that the ambient humidity is moderate (usually 40%-60%).
Avoid operating in an environment with too high or too low humidity to prevent abnormal curing reaction.
Clean the mold and master mold
The mold surface needs to be clean and free of oil, dust or other impurities to avoid affecting the curing effect of silicone.
Use a suitable release agent and ensure that the release agent is evenly applied to avoid excessive use causing atomization.
Equipment maintenance and calibration
Regularly check the mixing equipment, vacuum pump, temperature control system, etc. to ensure their normal operation.
Calibrate the metering equipment to ensure the accurate ratio of curing agent and silicone.
4. Mold design and optimization
Reasonable design of exhaust structure
The mold should be designed with reasonable exhaust holes or exhaust grooves to avoid the formation of atomization or pores due to the inability to discharge gas during the injection process of silicone.
Optimize mold surface treatment
The mold surface can be polished or sandblasted to improve the fluidity and curing effect of silicone.
Avoid sharp corners or unevenness on the mold surface to prevent stress concentration or surface defects after silicone is cured.
5. Quality inspection and improvement
Post-curing inspection
Perform an appearance inspection on the cured silicone products to observe whether there are defects such as fogging, pores, cracks, etc.
Use hardness testers, tensile testing machines and other equipment to test the physical properties of products to ensure that they meet the standards.
Data analysis and improvement
Record the data of each production (such as temperature, humidity, curing time, material batch, etc.) and analyze the causes of atomization.
Adjust process parameters or material formulas according to the analysis results to continuously optimize the production process.
6. Other precautions
Avoid cross contamination
Different types of silicone or curing agents cannot be mixed to prevent chemical reactions from causing abnormal curing.
Employee training
Provide professional training for operators to ensure that they are familiar with the characteristics and operating specifications of silicone materials and reduce fogging caused by human factors.
Through the comprehensive application of the above measures, atomization of liquid silicone products during the curing process can be effectively prevented, and product quality and production efficiency can be improved.