Antiseptic and bactericidal technology of cutting fluid 2
There are many chemicals that can kill microorganisms, but some characteristics of the cutting fluid system itself limit their application. Only by combining the aspects of system cleaning, selection of ideal preservatives, plant hygiene and system maintenance can we effectively solve the problems arising in the long-term operation process. This can not only extend the service life and improve the safety of the processing fluid, but also save costs.
Commonly used chemical preservatives have the following three mechanisms of action: The first category includes compounds that can cause the loss of membrane permeability, which leads to the leakage of cell contents and the loss of the energy gradient coupled with the membrane (such as phenols); The second category includes compounds that inhibit or inactivate intracellular enzymes, which are often combined with sulfhydryl reactions at the active site of the enzyme to affect the activity of the enzyme (such as aldehydes, formaldehyde derivatives); The third category includes the destruction of genetic material. These compounds prevent the cell from replicating, and even affect the synthesis of substances and the cell's respiration. Isothiazolinones not only damage the basic enzymes, but also affect the permeability of cell membrane and the synthesis of nucleic acid, so they have three kinds of mechanisms at the same time.
Taking into account the characteristics of water-based cutting fluid, the chemical preservatives applied in it should meet the following requirements:
1, the efficacy of a broad spectrum of microorganisms, in the recommended concentration can effectively kill bacteria, mold and yeast.
2, fast sterilization
3. Long-term performance
4, good compatibility with the ingredients in the processing fluid
5, good thermal stability
6, good material compatibility, such as does not rust the workpiece, does not destroy the sealing material
7, does not affect the cooling and lubrication performance of the processing fluid
8, little impact on the PH value of the processing fluid system
9, no negative impact on the environment, such as low odor, will not cause skin allergy, low toxicity and biodegradable
10. Reasonable cost
So far, no single active ingredient has been found that can well meet the requirements listed above. Therefore, preservative manufacturers can better meet the actual needs of metal processing by artificially optimizing the combination of different active ingredients.
Listed below are some of the active ingredients commonly used for metal working fluids protection.
1. Aldehydes
Among the aldehydes, formaldehyde, glutaraldehyde, benzaldehyde and chloroacetaldehyde are known, of which 30 to 40% of the formaldehyde aqueous solution is a simple form, which has a good anti-corrosion effect. However, formaldehyde only has a very strong killing effect on bacteria, and its effect on mold is relatively weak. Due to the irritating smell of formaldehyde, few people use pure formaldehyde as a preservative, and the application of glutaraldehyde has been paid more and more attention.
Second, formaldehyde derivatives
There are two forms of formaldehyde releasers: O-formaldehyde and N-formaldehyde. O-formaldehyde is produced by the reaction of primary alcohols, ethylene glycol or ethylene glycol ether with formaldehyde. Common ones are benzaldehyde, propylene glycol and 1, 2ethylenediol. They are less volatile than free methanol and therefore have better long-lasting properties. They are particularly suitable for use in neutral processing liquid systems. O-formaldehyde is a highly effective bactericidal ingredient, they are formed by the reaction of formaldehyde with amines or amino compounds, commonly hexahydrotriazine, imidazoline, acetal amine and hydroxymethylamide compounds.
Three, thiazoles/isothiazolinones
Over 30 years ago, this active ingredient was mentioned in the literature as having a good effect on bacteria and molds (such as 2-mercaptothiazoline or 2- (4-thiazolyl) -phenylimidazole). People have been trying to use them for the preservation of processing fluids. However, their application is restricted by solubility, stability and cost.
Phenylpropyl isothiazolone and other isothiazolinone derivatives have also been used as preservatives for several years. However, the composition and structure of the processing fluid will directly affect their efficacy. Due to the low solubility, the application of phenylpropyl isothiolinone is limited. The presence of amines, mercaptans and sulfites greatly affects the efficacy of the combination of chloromethyl isothiazolinone and methyl isothiazolinone. In addition, the combination of chloromethyl isothiazolinone and methyl isothiazolinone is highly toxic and corrosive to skin and mucous membranes when the concentration is high. So be very careful when doing this.
4. Phenols
In general, phenols play only a minor role in the anticorrosion of processing fluids. Like other active ingredients, phenols have their advantages and disadvantages. The advantage is that the speed of killing bacteria and mold is fast. However, when the PH value is > 9, the phenol-containing processing solution is easy to cause skin allergy. Moreover, the presence of non-ionic emulsifiers will cause the loss of bactericidal ability of phenols. For ecological and toxicity reasons, polyhalogenated phenols such as trichloro, tetrachloro or pentachlorophenol have been eliminated.
5. Cationic compounds
In terms of bactericidal efficacy, cationic active compounds can also be selected. However, due to its inability to kill common pseudomonas in water and its incompatibility with anionic emulsifiers, its application is limited.
6. 3-iodo2-propylene-butyl carbamate
3-iodo-2-propargyl-carbamate (3-Iodo-2-propargyl-carbamate) has been used more and more as an anti-mold agent in processing fluids. It can be used in both concentrates and diluents of processing fluids, but stability issues should be considered when used for concentration.
Seven, amines
Recent research results show that amines can provide good rust protection function and assist bactericidal function, and can maintain good activity in anionic system. However, in Germany, according to TRGS 611 (German Technical Specification for Toxic Substances), imines are prohibited in processing fluids because they form nitrosamines in the presence of nitrating agents.
It is not simple to add various active ingredients to the cutting fluid to achieve a good anti-corrosion effect. Due to more factors involved, and the diversity of bacteria, cutting fluid system differences and other reasons, the anti-corrosion technology put forward higher requirements. Choosing the right preservative is a key, and users should know the accurate use method. The use of preservatives should consult a professional preservative manufacturer.
Users should choose the appropriate preservative according to different cutting liquid systems and different processing materials. For example, KJ75 and MJN of Beifeng Chemical Company are suitable for alkaline systems, QKJ is suitable for neutral systems, and is especially suitable for non-ferrous metal processing. Principle of addition: In general, it is necessary to ensure that the concentration of preservatives in the working fluid of the circulating system is 0.15% during the day, so as to calculate the amount of preservatives required in the concentrated liquid according to the dilution ratio. And maintain the concentration of preservatives at work by adding them regularly (0.03%, 1-2 weeks per week).
Users can also choose the appropriate preservatives according to the different bacterial conditions of their respective systems. At present, in the domestic water-based cutting fluid market, the mainstream anti-corrosion active ingredients are hexahydrotriazines, such products are more effective against bacteria, but the effect of killing mold is very weak, lack of bactericidal broad spectrum, mold once invading cutting fluid, may lead to the formation of bacterial colonies, and then block the circulation system affect production.
wincide IMJ has the dual effect of killing both bacteria and mold. Can achieve a broad spectrum of effects, while inhibiting the growth of bacteria to prevent the emergence of mold. If the problem of odor often occurs in the cutting fluid system, QKJ and hexahydrotriazines can be selected to compare, which has much better inhibition of desulphurvibrio. Most of the cutting fluid formula added sulfonate as an anti-rust agent, the odor after the microbial problem is due to sulfonic acid in the sulfonic acid group is mostly decomposed by desulphurvibrio.
In addition to the addition of preservatives, daily microbiological testing and regular system cleaning are also essential. Microbes are too small to be seen by the naked eye. Therefore, a simple and intuitive method is needed to detect the growth of microorganisms.
System cleaning is a very important part that is often neglected. This link generally occurs when replacing the cutting fluid system, and some systems are dirty, such as microbial membranes in the pipeline. If the entire system is not fully cleaned before the new process fluid is injected into the system, the residual microorganisms in the system will quickly contaminate the new cutting fluid, thus putting additional pressure on the later corrosion protection of the system.
The system cleaning agent CJ35H from Beyform Chemical Company is a good helper. It is recommended that you add 1-3% concentration of CJ35H to the metal cutting fluid to be treated, and cycle for more than 6 hours (generally 8-12 hours), which can thoroughly clean the microorganisms, impurities and precipitation in the system. Then you can safely add the new cutting fluid.
With the improvement of the use effect, effective service life and environmental protection requirements of metal cutting fluids, more and more users have begun to pay attention to the role of preservatives. The fungicide used in cutting fluid has its particularity, and it is far from enough to rely on the fungicide alone. Only by combining the aspects of system cleaning, selecting the ideal preservative, plant hygiene and system maintenance, selecting the appropriate preservative and mastering the accurate use method according to the formula of the metal working fluid and the characteristics of the system, can we effectively solve the problems generated in the long-term operation process, extend the service life of the product and improve the performance of the product. Enhance the ability to adapt to environmental protection, thereby improving the competitiveness of products in the market. With more than 100 years of experience, Sumer provides first-class products. In addition, it can also provide a comprehensive solution for the microbial maintenance of water-based cutting fluid, truly making microbial contamination away from customers' products and production processes.
