Coating technology: screening of coating mildew microorganisms and anti mildew agents

Core tips: moldy microorganism: There are four types of microorganisms that can be tested in the laboratory, many of which are related to the mildew of coatings (1) mould: Aspergillus niger, Aspergillus flavus, Aspergillus versicolor, Penicillium citrinum, Paecilomyces vannamei（ Paint knowledge | precautions for wall paint color selection Recommended introduction: when painting the wall, the owner sometimes has difficulty in choosing what color of the wall paint to paint In fact, there is no ugly color in the wall paint, only the disharmonious color matching The use of wall color contains the knowledge of health Too strong color will stimulate people's perception, make people have a sense of fidgety, affect people's mental health Grasp the basic principles of wall color and paint a colorful space 1、 Wall paint color selection notice 1 Light color is generally used for the top surface Light colors make people feel light, dark colors make people feel heavy Usually, the treatment of rooms is from top to bottom, from shallow to deep For example, the ceiling and walls of rooms are white and Home of coatings: moldy microorganisms: there are four types of microorganisms available for testing in the laboratory, many of which are related to moldy coatings: (1) Aspergillus niger, Aspergillus flavus, Aspergillus versicolor, Penicillium citrinim, Paecilomyces varioti and Cladosporium cereus（ Cladosporium herbarum, Trichoderma viride, Chaetomium globosum (2) Bacillus megaterium, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Pseudomonas fluorescens (3) Klockeria janke, Saccharomyces cerevisiae (4) other common bacteria: Alternaria sp., aetinomucor elegans, Rhizopus sp., Aureobasidium pullulans, Pseudomonas NAS aeruginosa, Candida albicans Screening of antifungal and antibacterial agents: due to the wide variety and different properties of industrial antifungal and antibacterial agents, a series of screening tests must be carried out for a large number of antifungal and antibacterial agents to select a certain or several drugs to solve the problem of mold rot of coating industrial materials or products The requirements for the antifungal and antibacterial agents are as follows: as an ideal antifungal and antibacterial agent, it must meet the requirements of high efficiency, broad spectrum, low toxicity, long-term, stability, good mutual solubility, moderate price, sufficient supply, etc The color, smell, corrosiveness, solubility and other factors should also be considered It is quite difficult to fully meet the above requirements Therefore, in the actual use, the combination technology of two or more drugs can be used (1) At present, there are hundreds of industrial antifungal and antibacterial agents used in primary screening First, we need to have a basic understanding of the physical and chemical properties of various antifungal and antibacterial agents, and select the drugs needed to solve the problem of industrial materials or products mildew Secondly, we should do the test of the antifungal and antibacterial effects on the selected drugs This work is very important, otherwise, we can't find the medicine with good effect of anti mildew and anti bacteria In general, the plate bacteriostatic circle method is used for preliminary screening to investigate the inhibition capacity of the drug to mixed bacteria, mixed mold or mixed yeast And then select the drug with larger antibacterial circle, that is, the drug with strong mildew and antibacterial ability for further screening test (2) Based on the preliminary screening of mixed bacteria, mould or yeast, the minimum inhibitory concentration method (MIC method) is used to test the minimum inhibitory concentration of various microorganisms, so as to understand the antifungal and antibacterial effects of various drugs and provide necessary basis for the application of antifungal and antibacterial agents in certain industrial materials or products The mic data of a certain drug to all kinds of microorganisms are different, that is, the treatment effect of a certain antifungal and antibacterial agent to some or several microorganisms ① The addition test is also called the compatibility test, that is to say, the selected antifungal and antibacterial agents or compounds are added to the industrial materials or products in a certain proportion The tester must be familiar with the manufacturing process of industrial materials or products (from the selection of coating materials, feeding according to the formula, dispersion and grinding), so as to properly master the addition to a certain process The added antifungal and antibacterial agents should not only solve the problem of mould rot, but also affect the performance and quality of materials or coatings Otherwise, the antifungal and antibacterial agents can not be used For example, when antifungal and antibacterial agents are added to latex coating, attention should be paid to whether they affect the whiteness of the coating, whether they cause demulsification, whether they cause coating delamination and caking When the antifungal agent is added to the resin plastic, whether it can withstand high temperature; whether it can produce unpleasant smell; whether it can affect the color of the resin plastic; whether the pH value is appropriate when the antifungal agent is added to the metal processing liquid; whether it can corrode the mechanical equipment; when the antifungal agent is used for wood Whether the color of wood changes during anticorrosion must be considered ② The challenge test is to add a certain amount of microbial suspension to the industrial materials or products that have been added with anti mold and antibacterial agents, and test it under the appropriate temperature for a certain period of time after the mixture is even, and regularly observe the propagation of microorganisms in the sample, so as to judge whether the added anti mold and antibacterial agents can effectively solve the problem of product mildew As the test microorganism, if there is no special requirement, the laboratory routine test bacteria (mixed bacteria or mixed mold or mixed yeast) shall be used If there is special requirement, the contaminated bacteria isolated from a certain industrial material or product can be used, or two groups of bacteria can be used at the same time Add 1ml bacterial suspension to every 100g of sample, the bacterial content is 108cfu / ml The test time is 28 days, during which the test is carried out once every 7 days Generally, on the 7th, 14th and 21st day, the plate scribing culture method can be used to test the bacteria, and the "-", 10th, 10th and 10th "can be used to indicate whether or how many bacteria there are On the 28th day, viable count was performed Naturally, after 28 days of testing, the less bacteria in the sample, the better, indicating that the anti mold antibacterial agent has played a role; if the more bacteria in the sample, indicating that the added anti mold antibacterial agent and its formula are not good or effective, it should be re screened This test is suitable for latex coating, cosmetics, adhesives, metal processing fluid, paper pulp, ink ink, circulating water, oilfield water injection, etc ③ The culture dish test is to cut the sample which has been added with anti mildew and antibacterial agent into a certain size, place it in the center of the solid plate culture medium, then spray the mold spore suspension (108 CFU / ml), test it at (28 soil 1) ℃ for a certain time, check it every 7 days, and end the test at 28 days The degree of mould growth can be expressed by "-", 10, 10 and 10 It is better to be "-" after 28 days, that is, no mould growth The requirements for mildew resistance of industrial products can refer to national standards or industrial standards This law is applicable to coatings, textiles, leather, plastics, rubber, etc ④ In the application test, the formulation of anti mildew and anti bacteria agent obtained through a series of screening tests is added to the industrial materials or coatings that need to solve the problem of mould rot for production application test At the same time, samples were taken in batches to test the effect of anti mildew and anti bacteria and other properties Generally, if three batches of products are qualified, it is considered that the process is stable In addition, tracking service is also very important, because industrial products will encounter such or such problems in the manufacturing process, coupled with changes in environmental conditions, some of which will affect the anti mildew and antibacterial effect of products Problems found need to be improved in time Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,