Why does the coating with bactericidal preservatives still deteriorate
Why does the coating with bactericidal preservatives still deteriorate? Most of the antiseptic preservatives used in coatings on the market are non-ionic. This kind of antiseptic fungicide is a large consumption. With the acceleration of bacterial reproduction, antiseptic fungicides will gradually be consumed, and the concentration will gradually decrease; At the same time, bacterial reproduction may change the PH value of the paint environment, and the bactericidal effect of the anti-corrosion fungicide added in the paint will also be weakened
So, how do cationic antiseptic disinfectants kill bacteria? Before we start, let's say the pH value of the paint, generally 8.5~9, the pH value of most bacterial breeding environment is 3 ~ 4, and the nature of the surface charge of the bacterial cells in the water is controlled by the pH value, that is, when the pH value of the water is lower than the isoelectric point of the bacteria, the surface of the bacterial cells is positively charged, and vice versa.
Therefore, the general water and finished coatings are close to neutral or alkaline, so the surface of bacterial cells is negatively charged. The bactericidal principle of cationic antiseptic is mainly that the groups contained in it are positively charged in aqueous solution, which can be adsorbed on the surface of microorganisms to form microgroups, and gradually penetrate into the lipid layer and protein layer of microbial cytoplasm, thereby changing the permeability of the cell membrane and making the cell contents extravasate, resulting in microbial death;
At the same time, it can coagulate proteins, denature enzymes and structural proteins, destroy the metabolic system of microorganisms, and finally kill bacteria. After this round of sterilization, the cation is not consumed and can continue to play a role in killing.
Why does the coating with bactericidal preservatives still deteriorate? Precisely because antiseptic preservatives are not foolproof. Therefore, the choice of antiseptic should be careful.
First, do a compatibility test on the selected antiseptic and fungicide to see if it meets your paint system
Secondly, do a safety test on the selected antiseptic and fungicide, whether it is safe, for the surrounding equipment and personal safety.
Finally, the selected antiseptic fungicide should be rigorously tested to see if it can maintain antiseptic and bactericidal properties under bad circumstances.
In summary, the key to avoiding deterioration and odor of water-based coatings is to prevent bacterial contamination and anti-corrosion fungicide failure from production to packaging, storage and transportation. In addition to the selection of anti-corrosion fungicides, the production process of water, equipment cleaning and packaging cleanliness is also very important.
1. Try to avoid coating water with bacteria. In the high temperature season, try to avoid the use of sour and smelly washing water, avoid the use of groundwater, and avoid the use of storage tank water that has been stored for a long time. It is best to use purified water or tap water after disinfection to eliminate the chance of bacteria brought by production water.
2. The production machine should be kept clean. Especially some small factories, sometimes a few days do not produce, washing water is stored in the cylinder, the material in the sand mill is also easy to be infected by bacteria, must be cleaned before production.
3. Try to avoid bacteria in raw materials. The raw materials of water-based coatings should be stored in a dry and clean environment to avoid bacterial infection during storage. In particular, the emulsion should be opened and used now, and the one that can not be used up must be sealed. If cellulose is to be made into pre-gel, it must be used now, and it must not be stored in the high temperature season, otherwise it is very easy to be infected with bacteria. Other water-based additives should also be used on demand, and should be sealed in time.
4. In the production process, the PH regulator must not be mixed with preservatives to avoid the failure of water-based preservatives. When feeding, the two are also added separately as far as possible to reduce the impact on water-based preservatives.
5. In the production process, the temperature in the beating and sanding process should be controlled, and the temperature should not exceed 50℃ as far as possible to avoid the failure of water-based preservatives.
6. The amount of water-based preservatives in the high temperature season should be increased, and it is generally recommended to use some preservatives containing formaldehyde releases.
7. The packaging drum and lid should be kept in a dry and clean environment to reduce the possibility of mildew.
8. Packaging barrels and storage tanks are recommended to be sealed so as not to give bacteria an opportunity.
9. Avoid direct sunlight and high temperature during transportation and storage.
If the paint is infected, the mild should be used as soon as possible; The degree of heavy need to be sterilized, generally with sterilization agent or deodorant after treatment should be used as soon as possible. If it deteriorates, it can only be thrown away.
