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Special Topic on Anticorrosive and Antifungal Agents in Water-Based Coatings I. The Role of Anticorrosive and Antifungal Agents in the Coating Industry Anticorrosive agents prevent coatings from being damaged by bacteria and molds during storage in barrels or tanks; hence they are known as in-tank anticorrosive agents. If coatings are to be stored in barrels for an extended period of time, it is necessary to add such anticorrosive agents. Mold inhibitors are substances that ensure the paint film does not develop mold over a period of 5-10 years after application; they are known as dry-film mold inhibitors. High-end coatings not only require the use of preservatives but also include antifungal agents to enhance their antifungal performance after being applied to walls, thereby raising the overall quality of these coatings; this has made them the mainstream in the coating market. II. The importance of adding preservatives and antifungals to coatings. Coating preservatives are the most crucial among coating additives; if preservation fails, the entire quality system of the coating will collapse. However, due to the low amounts of preservatives and antifungals used, as well as insufficient awareness of these substances in China, paint manufacturers fail to recognize their importance. As a result, failure to prevent corrosion occurs frequently, causing significant losses to both paint manufacturers and those who use the paint. III. Main factors leading to the failure of coating corrosion protection: Due to the presence of nutrients such as water and cellulose in the coating system, if the preservatives do not eliminate bacteria thoroughly, or if secondary contamination occurs due to inadequate packaging after sterilization, this can result in problems with the coating. Especially in hot summer conditions, the paint is more prone to **. Generally speaking, the addition of preservatives to coatings enables effective bactericidal action. However, these preservatives only serve to sterilize the coating system (with the exception of formaldehyde-releasing type bactericides). There is air present in the upper layer of the packaging container, and this air contains bacteria. In hot weather during summer, these bacteria become more active. Especially when the coatings are stored outdoors, temperature differences between day and night cause the air in the upper layer of the packaging to condense into water droplets that fall onto the surface of the coating. These droplets contain a large number of bacteria. If the concentration of preservatives in the coating system is not sufficient to maintain an effective bactericidal level, it can lead to the failure of the entire coating system ； At the same time, as the air in the upper layer of the paint packaging condenses into water droplets that fall onto the surface of the paint, this effectively dilutes the concentration of preservatives on the paint’s surface, which can also lead to failure in corrosion protection. Furthermore, it is clear that the deterioration of the coating begins first at the surface of the coating and in those areas of the packaging container where the seal is not tight; in such places, the coating has usually already turned black. When it comes to the corrosion prevention of coatings, three parts depend on the preservatives and seven parts on the packaging containers; using recycled and cleaned containers for packaging products can easily lead to failure in corrosion prevention. Since the recycled packaging barrels contain water after being cleaned, and this water remains inside them while they are stored for future use, it provides the necessary conditions for bacteria to grow. As a result, bacteria multiply extensively within the barrels, leading to contamination of the packaging materials. Therefore, we should realize that a bucket that has been cleaned does not necessarily mean it is a \"clean\" bucket; any bucket in which raw water has been added to its contents is a contaminated bucket. Additionally, the application of anti-mold coatings should follow the following conditions and procedural principles: 1. Maintain good ventilation in the room ； 2. Renovated old walls and contaminated walls must be disinfected ； 3. Use anti-mold putty with an anti-mold agent added ； 4. Use a mildew-resistant primer with an anti-mildew agent added ； 5. Use latex paint with a mildew inhibitor. If one or both of these conditions are not met, it is easy to encounter problems with the failure of the dry film in preventing mold growth. This must draw the attention of industry professionals. Especially in areas where anti-mold coatings are required, if no anti-mold agents are added or the coating is not applied in accordance with the specified procedures, bacteria will attack the paint film under suitable temperature and humidity conditions. This leads to mold growth and darkening of the wall surface, as well as peeling of the paint film, resulting in an unclean and unsightly environment. In underground garages, air-raid shelters, ships, hospitals, biological laboratories, pharmaceutical factories, as well as in humid and hot environments in the south, coatings containing antifungal agents must be used to extend their performance quality and service life. IV. Strategies for effectively protecting coatings 1. Use relatively clean packaging drums with inner bags as much as possible. Use new packaging barrels as much as possible to ensure a sealed package; store it at room temperature, and avoid exposure to direct sunlight outdoors. If old packaging drums are used, it is better to apply a layer of paint inside them; some paint manufacturers in Shanghai are already using this method, and the results are excellent. Lined bags can also be used, but it is necessary to ensure that the opening of the bag is tightly sealed to prevent air from circulating inside and outside the bag. Furthermore, we find that it is easier to experience failure in corrosion prevention when using large packages, mainly because there are more ways in which large packages can cause contamination of the coating compared to small packages. For example, the black screw caps used on the commonly employed 50kg large-opening packaging drums are generally made from recycled plastic; if there is no lining cap, they will become the biggest direct source of contamination for coatings. 2. Use long-acting and potent fungicides and antifungals. Fungicides: Carboxin, which is widely used today, has the following insurmountable drawbacks: it can only be used at temperatures below 40°C, and its decomposition accelerates at temperatures above 40°C. The pH range in which carbendazim can remain stable is 2–4. Stabilizers need to be added during storage, but once these are incorporated into the coating system, the pH level rises to 7–9, and the stabilizers are diluted 1000 times. Thus, the two conditions necessary for carbendazim’s stability are altered, leading to an accelerated rate of decomposition. Generally, the maximum bactericidal effect is achieved 6 hours after adding carbendazim; after that, its components begin to decompose gradually. After 48 hours, the half-life is reached, and the carbendazim is almost completely degraded, losing its ability to protect the coating. If the coating system is subjected to secondary contamination at this point—such as bacteria present in the water droplets formed by air condensation on the packaging of the coating, which then fall into the coating and dilute the concentration of preservatives on its surface—the coating loses the protection provided by those preservatives, resulting in rapid bacterial growth and the breakdown of the entire coating system. It is recommended to use preservatives that combine fast-acting and long-acting bactericidal ingredients, so as to ensure thorough sterilization of the coating system and provide subsequent anti-corrosion protection. Traditional carbendazim-based fungicides no longer meet the requirements of the current domestic preservative market. Mold inhibitors: In terms of mold inhibitors used in coatings, liquid forms of these inhibitors in the form of emulsions with particle sizes ranging from 5 to 10 microns are generally used. The smaller the particle size, the more evenly the mold inhibitor is dispersed within the coating per unit weight; as a result, once the coating is applied to a surface, the mold inhibitor remains trapped within the paint film and does not easily leach away. Moreover, the denser the protective network formed by these mold inhibitor particles within the paint film, the greater its effectiveness in preventing mold growth. Generally speaking, pure liquid molecular antifungals can be used on interior walls, but when applied to exterior walls they cannot withstand the impact of rain, tend to wash away, and do not provide long-lasting protection; examples include Rohm and Haas’ M-8. Rocima 361 from Rohm and Haas and DF19 from German SuMei are excellent environmentally friendly antimicrobial agents in granular form that can be used on interior and exterior walls, basements, food factories, and other specialized environments; however, their active ingredient contents are 20% and 30% respectively, which is too low. Furthermore, the antifungal agent No. 75 produced in China contains arsenic trioxide, which is what people commonly refer to as arsenic. It is a highly toxic substance that poses risks to workers involved in the production of this antifungal agent, workers in paint manufacturing plants, those who apply the paint, and ultimately, to the residents who use the paint. The use of spraying methods during application poses a particularly serious risk to these workers; it can cause skin swelling and redness. Workers who are exposed to paint containing antifungal agent No. 75 over a long period may also experience the accumulation of organic arsenic in their bodies, leading to irreversible consequences such as poisoning! Organic arsenic tends to accumulate in the human body and in the environment, and it is not biodegradable; it has a particularly severe impact on children, causing irreversible harm to both humans and the environment. **The use of such products has already been banned. V. Mainstream preservatives and antifungals: The Mapch®101, 103, 104 series of preservative products – these are condensation formaldehyde-type preservatives and bactericides that provide excellent protection for the upper layer of the coating. A formaldehyde-release-controlled bactericide is included in these formulations; the free formaldehyde content in the bactericide solution is 0.5‰. An addition level of 1–2‰ does not cause the formaldehyde level in the coating to exceed 100 ppm. Once added to the coating system, in addition to killing bacteria within the coating itself, the slowly released formaldehyde penetrates the air in the upper part of the coating container and kills any bacteria present there, thereby keeping the entire system sterile or under bacterial control. Other similar products available on the market include: Koenig’s LFM from Germany ； Additionally, the German-Soviet DF35 and Thorne’s HF also belong to the same category of products. However, due to strict regulations on formaldehyde content in China, most domestic paint manufacturers are not optimistic about formaldehyde-release type bactericides. In fact, this is a misconception. Due to their low cost and excellent anti-corrosion properties, formaldehyde-based fungicides are widely used by large international companies such as Codecalon. Using a formaldehyde-release-type fungicide at the specified dosage will never result in an excessive formaldehyde content in the paint; moreover, it provides better protection for the upper layer of the paint than other types of fungicides can. Mapch®105, 106 long-lasting corrosion inhibitors: The Mapch®105 and Mapch®106 series represent the most effective bactericidal and corrosion-inhibiting agents available today. They can be used at temperatures up to 300°C, within a pH range of 4–12. Since these products have no special requirements regarding pH or temperature, they can be widely applied in coatings, inks, textile auxiliaries, and metal cutting fluid systems. Mapch®102 preservative product: Mapch®102 is an environmentally friendly multi-component bactericidal and preservative of the new generation for water-based systems. It contains no metal ions, volatile solvents, formaldehyde, or other highly toxic substances, and is widely used in water-based emulsions, latex paints, water-based adhesives, household cleaning products, inks, papermaking and paper sizing agents, metal cutting fluids, and color pastes. The recommended addition level of Mapch®102 is 1-2‰ (W/W). At an addition level of 3-5‰ (W/W), it can be used to sterilize **aqueous systems within 24-48 hours, achieving complete sterilization and effectively restoring the **aqueous systems, while also removing the colors and odors caused by **. Mapch®107, 111 – children’s paint preservatives and antifungals (compliant with EU restrictions on preservatives and antifungals): The Mapch®107 and Mapch®111 series are low-toxicity, environmentally friendly bactericidal, preservative, and antifungal agents. Mapch®107 contains no metal ions, volatile solvents, formaldehyde, or other toxic substances; its pure form causes little to no irritation to the skin, and its emissions are pollution-free, making it environmentally friendly ； It provides long-lasting bactericidal effects and is suitable for polyurethane systems as well as relatively fragile emulsion systems. It can replace carbazone-based bactericides, avoiding serious consequences such as emulsion coagulation caused by those bactericides. It can be applied in the cosmetics industry, toys (playdough), wood finishes, paints, as well as in the emerging category of children’s paints. The anti-corrosion and anti-mold agents in the Mapch®107 and Mapch®111 series meet the international requirements set by EU regulations such as ROHS, REACH, and EN71, thereby providing corrosion protection for products exported to other countries. Mapch®103, Mapch®104 multi-functional in-can sterilizing, preservative, and antifungal agent: This product’s formula contains sterilizing, preservative, and antifungal ingredients such as CMIT/MIT, BIT, and OIT, and it represents one of the most effective preservative formulas available today. Among them, CMIT/MIT serves to provide rapid sterilization, BIT offers long-term anti-corrosion effects, and OIT is used to eliminate mold in the coating system. Overall, Kason enables fast sterilization, while the other bactericidal components work together to prevent mold growth and remain in the coating system to provide ongoing protection, representing a perfect combination of short-acting and long-acting bactericidal agents. Thanks to its rational formulation, the product is not affected by temperature or environmental pH levels during use. By addressing sterilization, corrosion prevention, and mold inhibition, it provides comprehensive protection for water-based systems such as coatings; it can be used in emulsion, adhesive, and coating systems. Furthermore, another manifestation of Mapch®104’s bactericidal ability is that when 2-3‰ (w/w) of it is added to an existing aqueous system, it can sterilize that system and restore it to its normal state. Mapch®109 series of rapid restorers for degraded materials: Mapch®109 is the world’s latest generation of environmentally friendly, water-based rapid bactericide; at a concentration of 3-5‰ (W/W), it can quickly eliminate bacteria in degraded water-based systems and restore them to their original state. Generally speaking, after addition and thorough mixing, it can quickly eliminate various bacteria, fungi, and molds within a few seconds, and effectively remove colors, odors, and changes in properties caused by the deterioration of coatings and other substrates. It is the best rapid sterilizing and deodorizing agent for water-based substrates such as coatings and adhesives, and is used for professionally treating deteriorated coatings and other water-based systems. Products treated with Mapch®109 can be restored to their normal state. Mapch®109 can be widely used as a restorer to prevent deterioration in water-based emulsions, latex paints, water-based adhesives, inks, paper sizing agents, metal cutting fluids, and color pastes. Mapch®112, 113, 114 series of dry film antimicrobial agents: Mapch®112 antimicrobial agent incorporates excellent antimicrobial formulation designs from both domestic and international sources; it contains no metal ions, volatile solvents, formaldehyde, or other highly toxic components. Building on the effective antimicrobial ingredients such as Rohm and Haas’ Rocima 361, German Schüco DF19, and ISP (International Special Products) CD100, it also includes Rohm and Haas’ M-8 as an additional ingredient. This ingredient is equivalent to that in EPW, but at a concentration of 35% (w/w). Depending on the application environment – such as interior walls, exterior walls, basements, or food factories – the dosage required ranges from 5-7‰, 7-9‰, 9-15‰, and 2‰ (w/w) respectively. It contains effective fungicidal and algicidal ingredients, and is widely used in water-based emulsions, latex paints, water-based adhesives, as well as coatings for indoor and outdoor areas and basements. At the specified dosage levels, it can maintain its antimicrobial effect for 5-30 years. However, this formula imposes strict requirements on the coating application process and the principles for selecting materials. Generally speaking, when applying anti-mold coatings, especially on the walls of basements and food factories, it is necessary to ensure good indoor ventilation, disinfect the contaminated walls using multi-functional bactericidal and antifungal agents such as Mapch®103 and 104, and use putty containing anti-mold agents, as well as primers and coatings with anti-mold properties. The antifungal agents used in putty and primer can be those included in antifungal coatings, with the amount of these antifungal agents being the same as that used in antifungal coatings. Mapch®115 Marine Paint Antifungal and Algaecide: Mapch®115 provides long-lasting protection for marine paint, effectively preventing marine organisms from attaching to the ship’s hull. It offers excellent broad-spectrum antifungal, insecticidal, and algaecidal properties. It does not contain heavy metals, remains stable under strong ultraviolet light and acid rain conditions, and is harmless to the environment. The recommended concentration for marine paint is 5-15‰ (W/W), while for outdoor coatings it is 2-5‰ (W/W). VI. Precautions for the use of preservatives and antifungals 1. It is necessary to ensure that they are added separately, and not mixed with other additives, to avoid chemical reactions that could render them ineffective! Some factory workers, seeking convenience, often put fungicides and other additives into a small container before adding them all together to the coating mixture. This practice of mixing them together is quite common, but it also leads to problems quite frequently. 2. Preservatives and antifungals are biocides; avoid contact with skin. If contact with skin occurs or if it gets into the eyes, rinse immediately with plenty of water! No delay! 3. Preservatives and antifungals should be added as far as possible at the final dispersion step in coating production to ensure effective dispersion. When adding short-acting fungicides and antifungals, the temperature of the system should not exceed 40°C; long-acting fungicides and antifungals can be added at temperatures higher than 40°C. When using preservatives and antifungal agents, it is necessary to carefully read the product instructions and determine the optimal dosage based on experimental results, so as to achieve the desired preservative and antifungal effects without waste This post was last edited by zxh6267 on 2009-2-14 13:33.]