Ø  First, the characteristics of water-based metal working liquid

1, Although the situation pH:8-9.5 is not the most suitable for microorganisms, but mass reproduction is not affected

2, Temperature: the low temperature is enough to support the growth of microorganisms, not high enough to inhibit microbial growth

3, Usually contain high water which is conducive to microbial growth

4, The components contain sufficient nutrition

5, Recycling, while bringing in oxygen is conducive to microbial reproduction

6, The flow rate is not enough to resist the formation of biofilm

7, Carry waste, self-pollution

Ø  Second, common in water-based metalworking fluid

Bacteria:

Anaerobic bacteria (common ones are sulfate-reducing bacteria that produce hydrogen sulfide, etc.)

Aerobic bacteria (Escherichia coli, Pseudomonas, Staphylococcus aureus, Bacillus subtilis, etc.)

Fungi:

Mold: Aspergillus, Penicillium, Rhizopus nigra, cephalosporus, etc.

Yeast: red yeast, brewer's yeast, Candida, etc.

Ø  Three, microbial of metalworking fluid three major hazards

Metal working fluids, especially water-based metal working fluids and emulsions, are fertile breeding grounds for microbial growth.

(1) In the process of use, if they are allowed to grow and multiply without limit, it will cause the deterioration of the processing liquid and reduce the performance of the metal working liquid;

(2) The corrupt processing liquid will damage the processing machine tool, block the processing liquid processing system, damage the processing tool and processing workpiece;

(3) The growth and propagation of microorganisms will produce odor and corresponding compounds and affect the factory environment, stimulate the skin of the operator and cause allergic reactions and harm the health of workers.

Ø  Four, specific issues which microbial brings to the metal working fluid (water)

1. The working liquid is smelly, discolored and cloudy

2, Emulsification state is unstable, oil and water separation

3, Lead the metal surface or the tank sediment, blocking the oil circuit or filter

4. PH value drops

5, Corrosion to the equipment

6. The tendency to produce foam increases

7. The cutting ability decreases

Ø  Five, liquid metal processing with the requirements of the fungicide

1.      Broad spectrum and high efficiency, effective on bacteria, fungi and even algae

2.      Must be effective at low concentration (make its concentrate in 1:10, 1:15 and 1:20 times dilution to achieve sterilization effect)

3, In harsh conditions (high pH and even a certain high temperature) to maintain its chemical stability for a long time

4, The use cost is appropriate

5, Keep in the environmental regulations allowed value range

Ø  Six, the bactericidal preservative ingredient of cutting fluid

Isothiazolinones

(1) CIT/MIT: This product is mainly supplemented after the use of cutting fluid, effectively killing bacteria, mold and yeast. The general dosage is 100~ 200ppm.

(2) BIT 20: Its chemical name is 1,2-benzoisothiazolin-3-one. It is a broad-spectrum fungicide effective against bacteria, yeast and mold, with long term, low odor, pH range of 2-12, low toxicity, safety, especially excellent thermal stability. BIT 20 has good compatibility with other fungicides. It is often used in high temperature and strong alkaline environments where other preservatives do not work. It can be used in concentrates or working fluids. Recommended dosage (relative to diluent): 0.1-0.2%. its better used in combination with other fungicide.

(3) OIT: Its chemical name is (2-n-octyl-4-isothiazolin-3-one). It belongs to the broad-spectrum antifungal agent, and has certain bactericidal and algal action. Compared with other antifungal agents, OIT has wide range of compatibility, and a variety of metal processing liquid formula compatibility. However, it should be noted that OIT is unstable at high pH (> 9.5). Generally used for working fluid, recommended dosage (relative to diluent): 0.02-0.2%.

(4) MIT: Its chemical name is 2-methyl-4-isothiazolin-3-one. It is a broad-spectrum inhibitor of bacteria, molds and yeasts. Its long-term, low odor, no solvent, zero VOC, pH range 4.0-9.0, low toxicity, good safety, especially with excellent thermal stability. It can be used in concentrate or working solution. The recommended dosage is 100-300 PPM (diluent).

(5) BBIT: Its chemical name is -butyl-1,2-benzoisothiazolin-3-one. It is effective against bacteria, mold, yeast and some algae. It lasts for a long time, has low odor, and is suitable for pH range of 4-10. And has excellent thermal stability and chemical stability, at the same time has a wide range of compatibility. It can be used as a concentrate or working solution. Generally, 100-400 PPM (diluent) is recommended.

Organic halogens

(1) IPBC: Its chemical name is 3-iodide-2-propargyl–butyl methionine ester. It is a highly effective and low toxic fungicide. It is suitable for pH range of 4-10, long-term, cost performance; It has good prevention and killing effect on the fungi in the liquid system of metal processing (water-based and oil-based), and the dosage is 0.1-0.3%. IPBC has poor effect on bacteria and can be used in conjunction with antibacterial agents.

(2) DBNPA: Its chemical name is 2, 2-dibromo-3-azecramide. It is a high speed, high efficiency and low toxicity fungicide, which is effective against bacteria, mold and yeast. Its pH range is 3.0-9.5, and the temperature should not be higher than 50℃. Rapid hydrolysis in alkaline environment, when DBNPA effectively remove microbial pollution at the same time, there is little DBNPA residue in the system, its degradation of the final product is CO₂ and H₂O.Generally used for working fluid, recommended usage is 0.05-0.1%. The formula has good compatibility with isothiazolinone.

(3) Bronopol: Its chemical name is 2-bromo-2-nitro-1,3-propyl alcohol. It is a bactericide, especially against pseudomonas. Its pH range of 3.0-9.0. Generally used for working fluid, the recommended dosage is 350-1000ppm.The formula has good compatibility with isothiazolinone.

Triazines

Fungicide BK is a kind of fungicide widely used in metal working fluid. It can be used in concentrates or for on-site processing. Dosage: 0.1-0.25% of the current sterilization preservatives in the cutting fluid industry mainly to triazine (BK) as the main component of the bactericide (the product is a formaldehyde release). Because it can generally adapt to the alkaline PH value of the cutting fluid (the PH value of the cutting fluid is generally in 9-10), coupled with broad spectrum, it is still used by the majority manufacturers.

Morpholine

MBM is a morpholine derivative known by the chemical name N,N'-methylene dimorpholine. Broad-spectrum highly effective fungicide. Long-term, low odor, PH range of 4-12, small irritation to the skin, good compatibility in emulsified oil. General recommended dosage: 0.1-0.3% of the total weight of the product, can be used in combination with fungicide.

Oxazolines

Oxazoline fungicide, a broad-spectrum fungicide, especially good effect on sulfate-reducing bacteria, long-term, low odor, pH range of 7-11, none sensitization to the skin, good safety. At the same time has the function of amine, corrosion resistance, alkaline conditions with pH buffering ability, maintain the viscosity of emulsion. General working liquid use concentration of 0.04-0.2%.

Phenols

(1) OPP: Its chemical name is 2-phenylphenol. It belongs to the broad spectrum fungicide, also has a certain bactericidal performance. Its easy biodegradation, quick effect, especially suitable for high alkaline and high temperature systems. Generally, 0.1-0.25% for working liquid and 0.12-2.4% for concentrate. As this structural formula is irritating to the eyes, pay attention to the protection of the eyes when using.

(2) PCMX, PCMC, DCMX series: This series of products is a kind of safe and efficient anti-mildew antibacterial agent, no irritation, low toxicity. Good chemical stability, high temperature resistance, high pH resistance, usually will not be inactivated under storage conditions. Small solubility in water, easy to dissolve in alcohol, ether, ketone and other organic solvents and alkaline water solution. Suitable for concentrated solution anticorrosion and mildew proof system. Generally 1-3% is recommended.

Glutaraldehyde

Glutaraldehyde, belongs to broad spectrum, rapid sterilization, especially for SRBs, the structural form of low toxicity, easy biodegradation. It is suitable for a pH range of 7-10 and can be used in working fluids. A dosage of 200-2000ppm is generally recommended.

Others

There are many chemical fungicides that can be used for the biological stability of metal processing fluid. There is no best fungicide in the world, only the most appropriate fungicide.

Ø  Seven, well-known cutting fluid biocides and preservatives manufacturers

1. Schuelke & Mayr is a part of Vink Chemicals

It’s a German company, engaged in fungicide for more than one hundred years, the product applies in metal liquids include: Grotan OD, Grotan OX, Grotan BK, Grotan TK 5, Grotan TK 2, Grotan TK 6, Grotan Forte, Grotan F10. According to the analysis of the above products, we believe that they are mainly formulations based on BK, pyridine, OIT and formaldehyde releasers.

2. DOW (Dow Company)

The company is an American chemical company, involved in a wide range of fields. Antiseptic products in metal liquid include: BIOBAN P-1487, BIOBAN CS-1246, BIOBAN CS-1135, BIOBAN CM14, BIOBAN BIT20, DOWICIL QK20, SUMP BUDDY MWF, BIOBAN OIT45, BIOBAN I-20/40, DOWICIDE 1E, DOWICIDE A, DOWICIDE 25L, KATHON 886 MW, ROCIMA 640, KATHON 893 MW, KORDEK LX 5000, ROCIMA BT2S, and more. Through the regular analysis of the above Dow products, it is believed that the monomers are mainly isothiazolinone, morpholine, oxazoline, IPBC, DBNPA and OPP.

3. Lonza now it’s a part of Troy

Lonza is an American company that specializes in fungicides. Its preservative products involving water-based cutting fluids are:

DENSIL DG 20, DENSIL DN, Omacide IPBC 20, Omacide IPBC 30, Proxel GXL, Proxel TN, Reputain B30, Reputain K50, Sodium Omadine 10%, Sodium Omadine 40%, Sodium Omadine 2000, Triadine 3, Triadine 10, Triadine 20, etc. Mainly BIT, BK, IPBC, pyridine, Bronopol, glutaraldehyde basis formulations.

4. Clariant

Clariant is a Swiss company with a wide range of products. The main preservatives involved in the field of cutting fluids are: Nipacide MBM, Nipacide BK, Nipacide IPBC 30-DPG, Nipacide BIT 20, Nipacide CI, Nipacide OIT, Nipacide SP, Nipacleanden and so on. Customer analysis of the above Clariant products, that the monomer is CMIT/MIT, BIT, BK, MBM, IPBC, OIT, pyridine mainly, and on this basis.

Ø  Summarize

There are thousand kinds of fungicides used in metal processing fluid, but combined with the current common use of preservatives at domestic and abroad and the experience obtained in the practical application as follows:

(1) In terms of chemical fungicide, the bactericide above was sufficient to ensure the biological stability of water-based liquid.

(2) The combination of fungicide monomers is the development trend of preservatives to expand the bactericidal spectrum, reduce the cost and delay the generation of resistance.

(3) Metal working company hope that we provide not only fungicides, but solutions to problems. This puts forward higher requirements for our technical level: transition from the original simple application to coordinated application, and finally achieve comprehensive application. For example, different regions, different environments, different formula, different chemical compatibility, different addition methods, and even different water quality, its application effect and benefit are very different. Therefore, the antiseptic system is proposed in the hope that preservative enterprises and application units can be closely combined to enhance the application level of cutting liquid antiseptic.