Precautions for storage and use of silica sol

1、 Storage precautions

Temperature control: the optimal storage temperature is 5 ℃ -40 ℃, and it is strictly prohibited to be lower than 0 ℃. Icing is irreversible, and gel fails; Also, it should not be higher than 40 ℃ for a long time. It should be protected from light and exposure. High temperature will accelerate the polymerization and viscosity of silica sol particles, and in serious cases, gel will be scrapped.

Sealing and Container: It is necessary to use well sealed containers, and it is recommended to use polyethylene plastic drums. Metal containers such as iron and copper are prohibited (due to instability caused by metal ion precipitation). After opening, tighten the lid in a timely manner to avoid prolonged exposure and prevent water evaporation from causing silica sol crystallization and foreign objects such as impurities and dust to enter.

Environmental requirements: Store in a cool and dry place, avoid direct sunlight/ultraviolet radiation, prevent aging and microbial growth, and avoid mixing with strong acids, bases, electrolytes, salts, and other substances.

Shelf life management: Different types have different shelf lives, and alkaline silica sol has the best stability, with a shelf life generally greater than 1 year; The stability of acid silica sol is poor, and the shelf life is generally less than 1 year, so it needs to be used as soon as possible. It is recommended to use it up within 6 months after opening, and it needs to be checked after expiration. If there is gel, stratification, discoloration, and obvious increase in viscosity, it needs to be stored in isolation. If it fails to pass the re sampling test, it will be treated as a scrap process.

2、 Precautions for use

Pre processing: Before each use, it is necessary to stir thoroughly and evenly. After long-term storage, it is necessary to check for sedimentation and layering, and if necessary, filter before use.

Dilution with water: Dilute with deionized water, prohibit electrolytes, multivalent metal salts and cationic substances, and easily cause flocculation of gel.

Compatibility testing: Do not mix with strong acids, strong bases, high concentration salts, or strong oxidants as they may promote coagulation and reduce stability; Compatibility test shall be carried out with the external solvent first. For example, when mixed with acrylic lotion, a sample shall be taken in advance to verify the compatibility. After mixing, it shall be used up in a short time.

Scenario key points: Precision casting requires controlling the environmental humidity below 60% to avoid shell cracking. In the field of coatings, it is recommended to adjust the pH to 8-9 before adding silica sol to improve the stability and performance of the coating.

3、 Safety precautions

Silica sol itself is not a hazardous substance, but personal protection should be taken during operation, wearing latex gloves and safety goggles to avoid direct contact with the skin (which may cause dryness and cracking of the skin) and eye damage; If accidentally in contact with the skin, rinse with soapy water. After eye contact, immediately rinse with running water for at least 15 minutes and seek medical attention promptly. Wash the used storage barrels, pipes and pumps with water in time to avoid the residual gel of silica sol. The silica sol of gel is easy to block pipes and difficult to deal with after drying; Timely clean the site hygiene, and if necessary, carry out on-site disinfection work to prevent microbial contamination; Waste shall be disposed of in accordance with hazardous waste regulations, and arbitrary discharge is strictly prohibited; Maintain ventilation in the workplace and clean the body promptly after completion.

4、 Taboo items

1. Avoid freezing: After freezing, the colloidal structure of silica sol is damaged and cannot be restored.

2. Avoid electrolytes/cations: salts, multivalent metal ions, cationic additives, etc. can easily cause flocculation.

3. Avoid high temperature exposure: it will accelerate the aging and gel of silica sol.