Hygiene control and "MBA" microbial inspection in waterborne coatings factories
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Time：2024-07-03 13:04
To ensure that water-based coating products do not suffer from microbial contamination, on the one hand, suitable bactericides and preservatives must be selected for the product system to provide long-lasting protection; on the other hand, improving factory hygiene is also very important. The former ensures long-term preservation of the product, while the latter is for the prevention and control of microorganisms during the production process.
Poor factory environments lead to a large number of microorganisms in the finished products. If insufficient bactericides are added to the finished products, the microorganisms will multiply rapidly, leading to problems such as product spoilage, discoloration, odor, and reduced viscosity. In this case, the amount of bactericide added needs to be higher than the normal dosage, because part of the bactericidal active substance is used to kill the large number of existing microorganisms, and the remaining active substance is used for later preservation. Therefore, improving factory hygiene is crucial.
Production Raw Materials
· Production Water
Water is one of the main and essential raw materials in the production of water-based coatings, and it is also one of the raw materials most prone to microbial contamination. If the tank is easy to sample, it is recommended to sample both the tank and the pipeline outlet to ensure multi-point monitoring;
· Water-based Raw Materials
This includes emulsions, antifoaming agents, thickeners, and color pastes, which are prone to contamination. If there is no obvious contamination, a random sample of 1/3 – 1/2 of each type of raw material can be taken. If some samples show obvious contamination, the problematic samples should be sampled preferentially.
· Semi-finished Water-based Raw Materials
Slurry, cellulose pre-solution, prone to contamination. Usually there are not many tanks of this raw material, it is recommended to sample all of them.
· Powder and Solvent-based Raw Materials
Powder and solvent-based raw materials do not contain water and are not easy to breed microorganisms. Avoid moisture in the powder; however, sometimes the powder may contain spores, etc.
Production Equipment
· High-speed Dispersion Tank
Crusting is easy to occur at the inlet, and the inside of the crust is prone to contamination over time. It is recommended to empty it as much as possible; remove the crust; and sample and analyze the top cover and inner wall of the dispersion tank separately;
· Paint Mixing Tank
The inner wall and top cover are prone to residue, including the stirring shaft, etc. It is recommended that workers clean the inside of the paint mixing tank with a high-pressure water gun and brush; sample and analyze the paint mixing tank cover and inner wall;
· Packaging Line
Including packaging buffer tanks, outlets, and the water samples usually used to soak the outlets. The outlet and its soaking water are prone to contamination, so it is recommended to change it every half day. Sample the inner wall of the buffer tank, the outlet, and the soaking water;
Transfer Equipment
· Production Equipment
In coating production, there are also some transfer containers for auxiliaries or even coating products. If not cleaned properly, contamination is likely to occur. It is recommended to clean, drain, and place upside down. Sample the inner wall or bottom of the container;
· Transfer Pipelines and Interfaces
In coating production, there will be pipelines for transporting coatings or other liquids. If there is residual liquid, or the interface is constantly exposed to the air, contamination is likely to occur. It is recommended to empty the residual liquid in the pipeline as much as possible. Sample the liquid in the pipeline and the interface.
Laboratory Testing
After the samples are taken to the microbiology laboratory, streak the samples on microbial culture medium plates and place them in a microbial incubator for cultivation. Usually 48 – 72 hours are required. By observing the growth of colonies on the microbial culture medium, it is possible to determine whether the sample is contaminated with microorganisms and the level of contamination. This result also reflects the hygiene conditions of the raw materials and intermediate processes of production, so that the contaminated raw materials can be treated, or the contaminated equipment can be cleaned. This achieves effective control of the hygiene conditions during the coating production process.
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