news

BIT：1, 2-benzisothiazolin-3-one; MIT: 2-methyl-4-isothiazolin-3-one, both of which belong to the isothiazolinone type of in tank preservatives, mainly used for in tank anti-corrosion of water-based coatings, styrene acrylic lotion, adhesives, and inhibiting bacteria and yeast, are not dry film preservatives, but differ significantly in thermal stability, pH tolerance, sterilization characteristics, and regulatory restrictions.

1. Thermal stability and pH applicable range

BIT: excellent thermal stability, can withstand the high temperature of 100~150 ℃, and is not easy to decompose when added in the late stage of lotion polymerization and high temperature paint mixing stage; Suitable for a wide pH range, pH4～12， A strong alkali resistant system, high pH latex paint, concrete admixtures, and metal cutting fluids are very suitable for using BIT. MIT: Poor heat resistance, gradually decreasing activity at temperatures above 50-60 ℃, and prone to hydrolysis failure under high temperature conditions; Suitable for pH 2-8, stability deteriorates in alkaline environments, and can generally only be added in low-temperature, neutral/weakly acidic systems. It is not suitable for high-temperature processes and high pH formulations.

2. Sterilization characteristics and antibacterial spectrum

MIT: Fast sterilization speed, good efficacy against Gram negative bacteria (such as Pseudomonas and other dominant spoilage bacteria), suitable for quickly killing invading contaminating bacteria in the system; Weak ability to inhibit mold. BIT: It has stronger long-term antibacterial ability and a wider antibacterial spectrum. In addition to bacteria, it has inhibitory effects on yeast, mold, and some anaerobic bacteria; The sterilization effect is slower than MIT, and the advantage is that it can continuously inhibit bacteria during long-term storage, ensuring stable product shelf life.

3. Compatibility and System Influence

Both of them have good compatibility with lotion, anionic dispersant and wetting agent, and are not easy to demulsify. BIT remains stable in high alkaline systems; MIT is easily degraded under alkaline conditions, and an increase in system pH significantly shortens the effective storage time. Neither of them will cause significant discoloration of the paint film when used alone.

4. Safety, allergenicity, and regulations

MIT: There is a high risk of skin sensitization, and in recent years, domestic and foreign regulations have tightened the limit control of MIT in daily chemical and interior wall coatings; The use of indoor coatings and skin contact products requires strict control of the amount added. BIT: Sensitization is significantly lower than MIT, less irritating, and less restricted in the use of industrial water-based coatings and lotion. It is a mainstream in tank preservative in high pH industrial system.

5. Application scenarios and complex logic

· BIT: high-temperature production process, high pH emulsion paint, polymer lotion, metalworking fluid, sealant, long-term anti-corrosion in ink tank.

MIT: Low temperature, neutral/weak acidic system, pursuing rapid sterilization; Often compounded with BIT (BIT+MIT), combined with the advantages of MIT’s rapid sterilization and BIT’s long-term stability, it is a classic in tank anti-corrosion combination in the coating industry.

6. Core Summary

MIT focuses on quick acting sterilization, which is not resistant to high temperatures and strong alkalis, and has a high risk of sensitization; BIT focuses on high temperature resistance, alkali resistance, long-lasting broad-spectrum antibacterial properties, and lower irritation. Both are preservatives inside the tank, and cannot rely solely on BIT/MIT to achieve dry film mold prevention. Film mold prevention still requires the use of dry film mold inhibitors such as OIT and ZPT.