How to avoid excessive D4, D5, and D6 in silicone products,

To avoid excessive D4, D5, and D6 in silicone products, we can start from multiple links such as raw material selection, production process control, and finished product testing. The following are specific measures:
Raw material selection link
Select silicone raw materials with low or no D4, D5, and D6 content:
When purchasing silicone raw materials, require suppliers to provide detailed ingredient reports to clarify the content of D4, D5, and D6. Give priority to raw materials that have been strictly tested and whose D4, D5, and D6 content is far lower than the relevant regulatory limit standards (such as 0.1% stipulated in the EU REACH regulations).
For some application scenarios with extremely high quality and environmental protection requirements, such as infant products, medical devices, etc., you can even consider using special silicone raw materials that are clearly marked as free of D4, D5, and D6 to ensure product safety to the greatest extent.
Pay attention to the production process of raw materials: Understand the production process of silicone raw materials, because some production processes may be more likely to cause D4, D5, and D6 residues. For example, some silicone raw materials that use traditional processes and have not been finely purified may contain relatively high levels of D4, D5, and D6. Try to choose silica gel raw materials produced by advanced production processes (such as advanced polymerization reaction control technology, efficient purification process, etc.), which help reduce the generation and residue of impurities such as D4, D5, and D6.
Production process control link
Optimize polymerization reaction conditions:
In the production process of silica gel, polymerization reaction is a key step. Strictly control the parameters of polymerization reaction such as temperature, pressure, and reaction time. For example, inappropriate temperature may lead to incomplete polymerization reaction, which in turn increases the amount of unreacted D4, D5, D6 and other monomers. Through a large number of experiments and production practices, the most suitable polymerization reaction conditions are determined to ensure that D4, D5, and D6 can fully participate in the polymerization reaction and reduce their residues in the final silica gel products.
The polymerization reaction process is monitored in real time, and advanced instruments and equipment (such as online gas chromatographs, etc.) are used to monitor the concentration changes of D4, D5, D6 and other monomers in the reaction system, so as to detect abnormalities in time and make adjustments to ensure that the reaction proceeds as expected and effectively reduce the residues of these substances.
Strengthen purification and cleansing:
After the production of silica gel is completed, it is usually necessary to purify and cleanse it to remove impurities such as D4, D5, and D6 that may remain in it. Use appropriate purification methods, such as solvent extraction and adsorption. Solvent extraction can extract impurities using specific solvents; adsorption can adsorb impurities through adsorbents such as activated carbon and silica gel columns. Select appropriate purification and cleansing processes according to actual conditions and ensure their thoroughness to minimize the content of D4, D5, and D6.
Retest the purified and cleaned silica gel to confirm whether the content of impurities such as D4, D5, and D6 meets the requirements. If not, repeat the purification and cleansing steps until it meets the requirements.
Standardize the production environment and equipment cleaning:
Keep the production environment clean and hygienic to prevent pollutants such as D4, D5, and D6 in the external environment from mixing into the production process of silica gel products. Clean and disinfect the production workshop regularly, control the temperature and humidity of the workshop and other environmental conditions, and avoid dust, oil and other pollutants that may carry D4, D5, and D6 from contacting with silicone raw materials or products.
Clean and maintain production equipment regularly, because during the production process, some residues of silicone raw materials or products may remain on the surface of the equipment, and these residues may contain D4, D5, and D6. Use appropriate detergents and cleaning methods to thoroughly clean the equipment to ensure that the equipment is in a clean and residue-free state before each production, and prevent the D4, D5, and D6 residues from the previous batch of production from contaminating the next batch of products.
Finished product testing link
Establish a strict finished product testing system:
Develop a complete finished product testing process and standards, and clearly specify the testing frequency, testing methods (such as gas chromatography-mass spectrometry (GC-MS)) and limit standards (such as following the EU REACH regulations or the company's own more stringent internal standards) for the content of D4, D5, and D6 in silicone products.
Ensure that the testing work is completed by personnel or institutions with professional qualifications to ensure the accuracy and reliability of the test results.
Timely handling of products exceeding the standard:
Once the D4, D5, and D6 content in silicone products is found to exceed the standard, the products exceeding the standard should be immediately marked and isolated to prevent them from being mixed with qualified products and flowing into the market.
In-depth analysis of the reasons for exceeding the standard, check the factors that may cause the exceeding of the standard from various links such as raw materials and production processes, and take corresponding corrective measures, such as replacing raw materials, adjusting production processes, etc., and then re-test the rectified products until their D4, D5, and D6 content meets the standard requirements.