Aqueous semi-synthetic metalworking fluid composition containing a polyfunctional cyclic amine

Abstract

The present invention describes an aqueous semi-synthetic metalworking fluid comprising a base oil, an organic acid, an emulsifier, an additive concentrate, water, and a microbial growth control agent comprising a polyfunctional cyclic amine.

Description

Technical Field

[0001] The present invention relates to a method for controlling microbial growth in a metalworking fluid, which includes adding a specific class of polyfunctional cyclic amines to the metalworking fluid. Other embodiments relate to semi-synthetic metalworking fluid compositions containing a microbial growth control agent containing this specific class of polyfunctional cyclic amines.

Background Art

[0002] Introduction Metalworking fluids (MWFs) are used for lubrication during metal cutting and tool forming operations. These fluids help to cool the metalworking tools, remove chips from the tool / workpiece interface, and provide an acceptable machined finish. Amines are common MWF components widely used in various applications because of their properties of anti-corrosion, neutralization, and pH adjustment. Organic amines are usually used as corrosion inhibitors because MWFs are decomposed over time due to microbial growth that adversely affects fluid performance, and the microorganisms feed on the active components in the fluid.

[0003] Such microbial growth in MWFs can cause serious problems in metalworking processes in many forms, including general pickling of MWFs, changes in the viscosity of MWFs, shortening of the storage life of MWFs, and corrosion of tools and materials. In addition, the functions of equipment and processes such as supply nozzles, storage tanks, pipelines, and recycling system facilities can also be affected by microbial growth in MWFs. This pickling increases the cost of MWFs, accelerates the corrosion rate, and reduces the efficiency of metalworking. Therefore, in the MWF industry, the requirements for components that do not support microbial growth and maintain performance over a long period have not been met.

[0004] Therefore, the MWF industry has not met the requirements for components that do not support microbial growth and maintain performance over long periods. The most common solution is to add biocides and amine alcohols to a given MWF, either continuously or in batches. However, biocides and some secondary amine alcohols are restricted by regulatory limitations, and most biocidal chemicals release formaldehyde over time, which is harmful to human health.

[0005] Existing MWFs are typically classified as neat oil, soluble oil, semi-synthetic fluid, or synthetic fluid, each category exhibiting different functions such as cooling, lubrication, rust prevention, and cleaning. Soluble oil MWFs contain 50-70% by weight of neat oil, with the remainder being wear-resistant / extreme pressure additives and emulsifiers. Neat oils and soluble oils typically do not provide the same level of cooling as aqueous metalworking fluids. Synthetic fluids typically cannot provide good lubrication performance because their lubricating function is affected by the reverse dissolution of polyalkylene glycol when the temperature is above the cloud point. Semi-synthetic materials offer the potential to provide good lubrication and cooling simultaneously for use in demanding applications. Typical semi-synthetic fluids consist of oil, organic acids, emulsifiers, lubricants, amines, water, and other components. The amount of water in such a semi-synthetic MWF is typically up to 50-60% by weight, along with approximately 10-40% by weight of base oil, approximately 10-20% by weight of emulsifier, approximately 10-20% by weight of amine, and other functional additives such as acids, lubricants, solubilizers, and biocides. The semi-synthetic MWF is usually diluted at the end-user site with additional water to a base oil concentration of 1-20% by weight, more typically 5-7% by weight, by the weight of the diluted formulation.

[0006] In semi-synthetic fluids, emulsifiers are often added to form a stable dispersion in oil-in-water. Emulsifier particles are located around the oil droplets, imparting a negative charge that causes them to bond to water molecules. The size of such emulsified oil droplets is generally crucial for fluid performance, as smaller emulsion sizes allow for easier penetration into the interface of the cleavage zone. Emulsifiers also contribute to the stability of semi-synthetic fluids.

[0007] Semi-synthetic fluids partially degrade over time due to microbial growth, which negatively impacts fluid performance, as microorganisms feed on the active components in the fluid. Such microbial growth in MWF can cause serious problems in metalworking processes in many forms, including common pickling of MWF, changes in MWF viscosity, shortening of MWF shelf life, and corrosion of tools and materials. In addition, the functionality of equipment and processes such as supply nozzles, storage tanks, pipelines, and recycling system equipment can also be affected by microbial growth in MWF. This pickling increases the cost of MWF, accelerates the corrosion rate, and reduces the efficiency of metalworking. The most common solution to control microbial growth is to add biocides and amine alcohols to a given MWF, either continuously or in batches. However, biocides and some secondary amine alcohols are limited by regulatory restrictions, and most biocidic chemicals release formaldehyde over time, which is harmful to human health.

[0008] Therefore, it is desirable to have a novel semi-synthetic metalworking compound having a new biocidal composition that provides improved cooling, lubricity, concentration stability, and a long shelf life without the current environmental hygiene and safety concerns of the fluid.

[0009] The present invention addresses at least some of the needs described above. [Overview of the project]

[0010] The present invention relates to a method for controlling microbial growth in a metalworking fluid, the method comprising adding at least one specific class of polyfunctional cyclic amines to the metalworking fluid. The present invention also describes an aqueous semi-synthetic metalworking fluid comprising a base oil, an organic acid, an emulsifier, a concentrate additive, water, and a microbial growth control agent comprising a novel polyfunctional cyclic amine. [Modes for carrying out the invention]

[0011] Depending on their composition, metalworking fluids are classified as neat oils, soluble oils, semi-synthetic fluids, or synthetic fluids. Soluble oil MWFs contain 50-70% by weight of oil, with the remainder being wear-resistant / extreme pressure additives and emulsifiers. Semi-synthetic MWFs contain a significant amount, typically up to 50-60% by weight of water. Semi-synthetic fluids have a balanced lubrication and cooling performance, making them attractive for use as MWFs.

[0012] The present invention relates to a novel material that can be used as an antimicrobial agent for use in semi-synthetic metalworking fluids and such fluids. The substance of the present invention is a polyfunctional cyclic amine corresponding to the following formula (I):

[0013] [ka] In the formula, each R, T, U, V, W, X, Y, and Z group in formula (I) above is independently selected from hydrogen or a hydrocarbyl group, and the value of x is 0 to 10. The hydrocarbyl group that can be used in the embodiment of the present invention may be substituted (typically with N, O, or S atoms) or unsubstituted, and may be linear, branched, or cyclic hydrocarbyl such as alkyl, aryl, or aralkyl groups, may be monovalent moieties containing one or more heteroatoms, may be polyether chains containing one or more oxyalkylene repeating units such as -R1O- (wherein R1 is an alkylene with 2 to 5 carbon atoms), or may be other oligomeric or polymer chains with at least two repeating units. In one embodiment, R, T, U, V, W, X, Y, and Z are H, or linear, branched, or cyclic hydrocarbyl such as alkyl (such as a methyl or ethyl group) with 1 to 10 carbon atoms, preferably 1 to 3 carbon atoms. In another embodiment, R, T, U, V, W, X, Y, and Z are H. The value of x in the embodiment of the present invention is typically in the range of 1 to 10, preferably in the range of 2 to 5, more preferably in the range of 2 to 3, and most preferably in the range of 0 to 1.

[0014] Such cyclic polyamines are commercially available or can be produced by amino group transfer of cyclic amines as is commonly known in the art. Examples of high molecular weight cyclic polyamines that are useful in the present invention and match formula (I) include bis(2-(piperazin-1-yl)ethyl)amine (BPEA), (3-(piperazin-1-yl)propyl)amine, bis(4-(piperazin-1-yl)butyl)amine, bis(5-(piperazin-1-yl)pentyl)amine, bis(6-(piperazin-1-yl)hexyl)amine, bis(1-(piperazin-1-yl)propan-2-yl)amine, bis(2-(piperazin-1-yl)propyl)amine, and mixtures thereof.

[0015] One preferred embodiment of a cyclic polyamine compound useful for preparing the composition of the present invention is, for example, bis(2-(piperazine-1-yl)ethyl)amine (BPEA), high molecular weight BPEA oligomers, and mixtures thereof. The MWF of the present invention comprises water, one or more base oils, one or more organic acids, one or more emulsifiers, one or more lubricants, and one or more amines, wherein the amines function as pH adjusters and / or microbial growth regulators, and at least one amine comprises at least one cyclic polyamine of formula (I).

[0016] The microbial growth regulator may further comprise one or more additional antimicrobial materials, such as glycol etheramines, which can be used in combination with the materials disclosed above to achieve specific microbial growth control objectives. The concentration of the microbial growth regulator / pH adjuster in the MWF (containing the cyclic polyamine of formula (I)) may range from 1, 4, 6, 8, or 10 weight percent of the formulation to 30, 25, 15, or 12 weight percent of the formulation. Preferably, the cyclic polyamine(plural) of formula (I) may comprise 2, preferably 3, or even more than 5 weight percent of the MWF to 25, preferably 20, or even more than 15 weight percent.

[0017] The semi-synthetic MWF of the present invention also includes a base oil. The base oil may be any base oil generally known in the art for use in MWF. Preferably, the base oil is selected from tall oil, naphthenic oil, paraffinic oil, or ester oil, or a combination thereof. The concentration of the base oil(s) in the MWF may range from 5, 7, 10, or 15 weight percent of the composition to 50, 45, 40, or 35 weight percent of the composition.

[0018] The water used in these formulations is preferably deionized water and may contain at least 20, preferably 25, 30, or even 35 weight percent of the formulation, up to a maximum of 70, 65, 60, 55, or even 50 weight percent of the formulation. These formulations may be further diluted with additional water before use, and these ranges are intended to be modified accordingly. For example, before use, the formulation may be diluted so that the base oil concentration is 1 to 20 weight percent, more typically 5 to 7 weight percent, of the diluted formulation.

[0019] The semi-synthetic MWF of the present invention also contains one or more organic acids as solubilizers and / or corrosion inhibitors. Preferred organic acids include 2-ethylhexanoic acid, azelaic acid, tall oil fatty acids, 12-hydroxyl-(cis)-9-octadecenoic acid, dicarboxylic acid, and 9-octadecenoic acid. The concentration of the organic acid in the MWF may range from 2, 3, 4, or 5 weight percent of the composition to 12, 10, 8, or 7 weight percent of the composition.

[0020] The semi-synthetic MWF of the present invention also comprises one or more emulsifiers. The emulsifiers may be anionic, cationic, or nonionic. Examples of suitable anionic surfactants or emulsifiers are alkali metals, ammonium, and amine soaps. The fatty acid portion of such soaps preferably contains at least 10 carbon atoms. The soaps can also be formed in situ, in other words, by adding fatty acids to the oil phase and alkaline materials to the aqueous phase.

[0021] Other suitable anionic surfactants or emulsifiers include alkali metal salts of alkyl-aryl sulfonic acids, sodium dialkyl sulfosuccinate, sulfated or sulfonated oils, such as sulfated castor oil; sulfonated animal fats; and alkali salts of short-chain petroleum sulfonic acids.

[0022] Suitable cationic surfactants or emulsifiers include salts of long-chain primary, secondary, or tertiary amines, such as oleylamide acetate, acetylamine acetate, didodecylamine lactate, acetate of aminoethyl-aminoethyl stearamide, dilauroyltriethylenetetraminediacetate, and 1-aminoethyl-2-heptadecenylimidazoline acetate; as well as quaternary salts, such as cetylpyridinium bromide, hexadecylethylmorpholinium chloride, and diethyldidodecylammonium chloride.

[0023] Examples of suitable nonionic surfactants or emulsifiers include condensation products of higher fatty alcohols and ethylene oxide, e.g., reaction products of oleyl alcohol and 10 ethylene oxide units; condensation products of alkylphenols and ethylene oxide, e.g., reaction products of isooctylphenol and 12 ethylene oxide units; condensation products of higher fatty acid amides and 5 or more ethylene oxide units; polyethylene glycol esters of long-chain fatty acids such as tetraethylene glycol monopalmitate, hexaethylene glycol monolaurate, nonaethylene glycol monostearate, nonaethylene glycol dioleate, tridecaethylene glycol monoarachidate, tricosaethylene glycol monobehenate, and tricosaethylene glycol dibehenate; and polyhydric alcohol partial higher fatty acid esters such as sorbitan tristearate. These include ethylene oxide condensation products of polyhydric alcohol partial higher fatty acid esters and their intramolecular anhydrides (such as mannitol anhydride, also called mannitane; sorbitol anhydride, also called sorbitan), for example, glycerol monopalmitate reacted with 10 molecules of ethylene oxide, pentaerythritol monooleate reacted with 12 molecules of ethylene oxide, sorbitan monostearate reacted with 10-15 molecules of ethylene oxide, mannitane monopalmitate reacted with 10-15 molecules of ethylene oxide, etc.; and long-chain polyglycols in which one hydroxyl group is esterified with a higher fatty acid and the other hydroxyl group is etherified with a low molecular weight alcohol, such as methoxypolyethylene glycol 550 monostearate (where 550 means the average molecular weight of polyglycol ethers). Two or more combinations of these surfactants may be used; for example, cationic surfactants may be blended with nonionic surfactants, or anionic surfactants may be blended with nonionic surfactants.

[0024] Particularly suitable emulsifiers include ethoxylated or propoxylated C16-C18 alcohols; ethoxylated C12-C15 alcohols; sodium alkanesulfonates and alkyl ether carboxylates.

[0025] The concentration of the emulsifier(s) in the MWF can range from 4, 5, 6, 8, or 10 weight percent of the formulation to 25, 20, 15, or 12 percent of the formulation.

[0026] The semi-synthetic MWF of the present invention may also contain one or more concentrated additives. When present, preferred concentrated additives include diethylene glycol butyl ether, ethylene glycol monobutyl ether, and propylene glycol butyl ether. When present, the concentration of the concentrated additive(s) in the MWF can range from 0.3, 0.5, 1.0, or 1.5 weight percent of the formulation to 2.5, 2.0, or 1.8 percent of the formulation.

[0027] The semi-synthetic MWF of the present invention may also contain other additives to provide additional functionality generally known in the art.

[0028] The microbial growth controlled by the biocides of this disclosure typically consists of contaminants, which are mixtures of bacteria and fungi. Some typical fungal and bacterial contents include, but are not limited to, Aeromonas hydrophila (ATCC 13444), Candida albicans (ATCC 752), Desulfovibrio desulfuricans (ATCC 7757), Escherichia coli (ATCC 8739), Flavobacterium ferrugineum (ATCC 13524), Fusarium oxysporum (ATCC 7601), Klebsiella pneumoniae (ATCC 13883), Proteus mirabilis (ATCC 4675), Pseudomonas aeruginosa (ATCC 8689), Pseudomonas oleovorans (ATCC 8062), and Saccharomyces cerevisiae (ATCC 2338). The strains listed above can vary throughout the world, and the present invention is fully envisioned as a broad-spectrum microbial growth regulator and / or biocide that can be used against any common MWF microbial contaminants. [Examples]

[0029] Experiments to test the effectiveness of formulations containing the microbial growth control agent of this disclosure may be carried out as follows. Table 1 includes a description of the materials used in these examples.

[0030] [Table 1]

[0031] Using the different amines listed in Table 3, a series of formulations are prepared according to Table 2.

[0032] [Table 2]

[0033] [Table 3]

[0034] Prepare the concentrated formulation as follows: Pour the indicated amount of deionized water into a container. Add mineral oil, EcoSurf SA-7, Dowfax 20A42, secondary alkanesulfonate, tall oil acid, and diacitic acid (sebacic acid) to the water. Stir the formulation with a magnetic stirrer at 200 rpm and 60°C for 1 hour. Add the indicated amine as a pH adjuster.

[0035] Next, dilute the concentrated formulation 20-fold with process water, tap water, or deionized water (shown in Table 3) based on the total volume of the concentrated formulation. Test the pH value using a pH titrator (Mettler Toledo: #SevenMulti). If the pH value of the diluted formulation is below 9.5, add an additional 1-2 drops of monoethanolamine to raise the pH value to at least 9.5.

[0036] pH aging test: The pH values ​​of the prepared dilution formulation are tested at 0 and 14 days using a pH titrator (Mettler Toledo: #SevenMulti). The sample is left at room temperature.

[0037] [Table 4]

[0038] The pH decrease after two weeks of aging should be as small as possible. IE1 with bis(piperazine ethyl)amine, AMP-95, and CE2 and CE3 with dicyclohexylamine are at a similar level, with pH loss controlled within 5%. CE1 with monoisopropanolamine is not as good, in that its pH loss exceeds 10%.

[0039] Aluminum corrosion test: Wash the aluminum flakes (#ADC12) with alcohol and weigh them. Immerse the aluminum flakes in the test solution at 40°C for 48 hours using a lidded vial (half the volume of the aluminum flakes is in the solution and the other half is exposed to air). Observe the corrosion of the aluminum flake surface, measure the weight loss of the aluminum flakes, and detect the aluminum content in the formulation using an ICP-OES (Inductively Coupled Plasma Emission Spectrometer: Perkin Elmer: #Optima 5300DV).

[0040] [Table 5]

[0041] The ICP-OES data shows agreement with qualitative observations of aluminum flake corrosion. Larger areas with yellow coloration indicate more severe corrosion and a higher aluminum content in the test fluid. Qualitative descriptions such as "Pass," "Limited," or "Fail" are added to explain the observed results relatively. The ICP-OES data shows CE6 with dicyclohexylamine corroding aluminum exceeding 1 ppm leaching from the flakes. Sample CE6 has the worst appearance and the largest area of ​​rust. For the other samples, including IE1, CE4, and CE5, the aluminum leaching from the flakes is less than 1 ppm.

[0042] pH value in antimicrobial testing: The sample is handled according to the ASTM E 2275 method. This method can be summarized as follows:

[0043] The inoculum is a mixture of ATCC strains of bacteria and fungi listed in Table 6. The emulsion product mixture inoculum is prepared by adding 0.1 mL of each bacterial overnight broth culture and 1.0 mL of each yeast broth culture to 10 mL of mold suspension and blending them together.

[0044] 0.5 mL of the mixed inoculum is administered to 50 grams of sample. This inoculation attacks emulsion samples containing high levels of microorganisms (10⁶–10⁷ colony-forming units per gram of sample, CFU / g). The attacked samples are mixed and stored in an incubator at 30°C for 7 days. This process is repeated five additional times, with the following amounts of inoculum added to each sample: 0.5 mL for the second inoculation, 1.0 mL for the third, 1.0 mL for the fourth, and 3.0 mL for the fifth. The pH value of the inoculated emulsion samples is tested at the end of the 5-week protocol and compared to the initial pH value of the emulsion before colony addition.

[0045] [Table 6]

[0046] [Table 7]

[0047] IE3, containing bis(piperazine ethyl)amine, shows only a pH decrease of 0.12 in antimicrobial evaluation. CE7, containing monoisopropanolamine, shows a pH decrease of 0.30 in antimicrobial evaluation. Therefore, the microbial stability of IE3 is expected to be better than that of monoisopropanolamine when used in metalworking fluid formulations.

Claims

1. A semi-synthetic metalworking fluid, a. At least one base oil and b. 【Chemistry 1】 Structure A microbial growth control agent comprising an alkylamine having (wherein in formula (I) above, each R, T, U, V, W, X, Y, and Z is independently selected from hydrogen or a hydrocarbyl group, and the value of x is independently 0 to 10), c. One or more organic acids, d. One or more emulsifiers, e. One or more concentrated additives, f. A semi-synthetic metalworking fluid containing water.

2. The semi-synthetic metalworking fluid according to claim 1, wherein R, T, U, V, W, X, Y, and Z in the microbial growth control agent are each H.

3. The semi-synthetic metalworking fluid according to claim 1, wherein the microbial growth control agent is bis(2-(piperazine-1-yl)ethyl)amine (BPEA).

4. The semi-synthetic metalworking fluid according to claim 1, wherein the microbial growth control agent further comprises another amine.

5. The semi-synthetic metalworking fluid according to claim 1, wherein the base oil is selected from naphthenic oil, paraffinic oil, ester oil, and mixtures thereof.

6. The semi-synthetic metalworking fluid according to claim 1, wherein the emulsifier is selected from ethoxylated or propoxylated C16-18 alcohols, ethoxylated C12-C15 alcohols, sodium alkanesulfonates, alkyl ether carboxylates, and mixtures thereof.

7. The semi-synthetic metalworking fluid according to claim 1, comprising one or more organic acids as a solubilizer / corrosion inhibitor, wherein the solubilizer / corrosion inhibitor is selected from ethylhexanoic acid, azelaic acid, tall oil fatty acid, 12-hydroxyl-(cis)-9-octadecenoic acid, dicarboxylic acid, 9-octadecenoic acid, sebacic acid, and mixtures thereof.

8. The semi-synthetic metalworking fluid according to claim 1, wherein the concentrating additive is selected from diethylene glycol butyl ether, ethylene glycol monobutyl ether, propylene glycol butyl ether, and mixtures thereof.

9. The semi-synthetic metalworking fluid according to claim 1, wherein the microbial growth control agent is present in an amount of 6 to 15 weight percent of the semi-synthetic metalworking fluid.

10. The semi-synthetic metalworking fluid according to claim 1, wherein the base oil is present in an amount of 10 to 45 weight percent of the semi-synthetic metalworking fluid.

11. The semi-synthetic metalworking fluid according to claim 1, wherein the emulsifier is present in an amount of 5 to 20 weight percent of the semi-synthetic metalworking fluid.

12. The semi-synthetic metalworking fluid according to claim 1, comprising one or more organic acids as a solubilizer / corrosion inhibitor, wherein the solubilizer / corrosion inhibitor is present in an amount of 3 to 10 weight percent of the semi-synthetic metalworking fluid.

13. The semi-synthetic metalworking fluid according to claim 1, wherein the water is present in an amount of 20 to 60 weight percent of the semi-synthetic metalworking fluid.

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