Semi-synthetic metalworking fluid composition based on water with a cyclic polyfunctional amine

Description

[0001] The current invention relates to a method of controlling microbial growth in metal working fluids, comprising adding a particular class of cyclic polyfunctional amines to the metal working fluid. Other embodiments relate to semi-synthetic metal working fluid compositions which include the microbial growth control agent comprising this particular class of cyclic polyfunctional amines.INTRODUCTION

[0002] Metal working fluids (MWFs) are used for lubrication of metal cutting and tool forming. These fluids provide cooling for the metal work tooling, removal of cutting chips from the tool / work piece interface and help provide an acceptable post-machining finished surface. Amines are a popular MWF component widely used in a variety of applications due to their properties of anti-corrosion, neutralization, and pH adjustment. Organic amines are usually used as corrosion inhibitors because MWFs are degraded over time due to microbial growth which is negatively impact fluid performance and the microbes feed on the active ingredients in the fluid.

[0003] Such microbial growth in the MWFs may cause serious problems in metalworking processing in many forms including: MWFs general souring, MWFs viscosity changing, MWFs shelf life shortening, and the corroding of tools and materials. Additionally, the functioning of equipment and processes such as feeding nozzles, storage tanks, pipelines and recycling system facilities may also be impacted by microbe growth in MWFs. This souring increases the cost of MWFs, accelerates corrosion rates and decreases efficiency of metal processing. Thus, there is an unfulfilled need in the MWF industry for components which do not support microbial growth and maintain performance over a long time.

[0004] Thus, there is an unfulfilled need in the MWF industry for components which do not support microbial growth and maintain performance over a long time. The most common solution is to add biocides and amine alcohols either continuously or as a batch treatment to a given MWF. However, biocides and some secondary amine alcohols are limited by regulatory restrictions and most of the biocide chemicals will release formaldehyde over time which is hazardous to human health.

[0005] Existing MWFs are typically classified as neat oil, soluble oil, semi-synthetic fluid, or synthetic fluid, with each category exhibiting different functions of cooling. lubricating, anti-rust and cleaning. Soluble oil MWFs comprise 50-70 wt.% neat oil with the remainder of the MWF being anti-wear / extreme pressure additives and emulsifiers. Neat oils and soluble oils typically do not provide the same level of cooling compared with water-based metalworking fluids. Synthetic fluids typically cannot provide the good lubricity performance because their lubricity function is affected by polyalkylene glycol reverse dissolution when the temperature is higher than cloud point. Semi-synthetic materials offer the possibility of simultaneously providing good lubricity and cooling for use in demanding applications. A typical semi-synthetic fluid consists of oils, organic acid, emulsifiers, lubricants, amines, water and other ingredients. The amount of water in such semi-synthetic MWFs is typically up to 50-60 wt.%, with around 10-40 wt.% base oil, around 10-20wt.% emulsifiers, around 10-20 wt.% amine, and other functional additives such as acid, lubricant, solubilizer, biocide etc. Semi-synthetic MWFs are usually diluted with additional water at an end user's site to a base oil concentration of 1-20 wt.%, more typically 5-7 wt.% concentration by weight of the diluted formulation.

[0006] In semi-synthetic fluids, emulsifiers are often added to form stable dispersion of oil in water. Emulsifier particles are located around the oil droplets to give them a negative charge that will bind them to the water molecules. The size of such emulsified oil drops is very important to fluid performance, as it is generally easier for the smaller emulsion sizes to penetrate the interface of the cutting zone. The emulsifiers also contribute to the stability of semi-synthetic fluids.

[0007] Semi-synthetic fluids will degrade over time in part due to microbial growth which negatively impacts fluid performance because microbes feed on the active ingredients in the fluid. Such microbial growth in the MWFs may cause serious problems in metal working processing in many forms including: MWFs general souring, MWFs viscosity changing. MWFs shelf life shortening, and the corroding of tools and materials. Additionally, the functioning of equipment and processes such as feeding nozzles, storage tanks, pipelines and recycling system facilities may also be impacted by microbe growth in MWFs. This souring increases the cost of MWFs, accelerates corrosion rates and decreases efficiency of metal processing. The most common solution to control microbial growth is to add biocides and amine alcohols either continuously or as a batch treatment to a given MWF. However, biocides and some secondary amine alcohols are limited by regulatory restrictions and most of the biocide chemicals will release formaldehyde over time which is hazardous to human health. EP3135109 is concerned with biocidal compositions comprising primary amino alcohols and their use as metal working fluids in aqueous media.

[0008] It is therefore desired to have new semi-synthetic metal working formulations with new biocidal compositions which provide improved cooling, lubricity, concentrate stability, and long shelf life, without the environmental health and safety concerns of present fluids.

[0009] This invention addresses at least some of the above-described needs.SUMMARY

[0010] The present invention relates to a method of controlling microbial growth in metal working fluids, wherein the method includes the addition of at least one of a particular class of cyclic polyfunctional amines to the metal working fluid. The present invention also describes a water based semi-synthetic metal working fluid comprising a base oil, an organic acid, emulsifiers, a concentrate additive, water and a microbial growth control agent which comprises the novel cyclic polyfunctional amine.DETAILED DESCRIPTION

[0011] Depending on their composition, metal working fluids are classified as neat oil. soluble oil, semi-synthetic fluid, or synthetic fluid. Soluble oil MWFs comprise 50-70 wt.% oil with the rest being anti-wear / extreme pressure additives and emulsifiers. Semi-synthetic MWFs contain a significant amount of water, typically up to 50-60 wt.%. Semi-synthetic fluids have balanced lubricity and cooling performance and are thus attractive for use as MWFs.

[0012] The present invention relates to semi-synthetic metal working fluids, and new materials which can be used as antimicrobials for use in such fluids. The materials of the present invention are cyclic polyfunctional amines corresponding to the following formula (I): wherein 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. Hydrocarbyl groups that may be used in the practice of the invention may be substituted (typically with N. O, or S atoms) or unsubstituted. linear, branched, or cyclic hydrocarbyl such as alkyl, aryl, aralkyl, or the like; a monovalent moiety including one or more heteroatoms; polyether chains comprising one or more oxyalkylene repeating units such as -R 1 O-, wherein R 1 is an alkylene of 2 to 5 carbon atoms; other oligomeric or polymer chains of at least 2 repeating units. In an embodiment, R, T, U, V, W, X, Y, and Z are H or straight, branched, or cyclic hydrocarbyl such as alkyl of 1 to 10 carbon atoms, preferably 1 to 3 carbon atoms such as methyl or ethyl groups. In another embodiment, R. T, U, V, W, X, Y, and Z are H. The values of x in the practice of the invention are typically in the range of from 1 to 10, preferably in the range of from 2 to 5. and more preferably in the range of from 2 to 3 and most preferably in the range of 0-1.

[0013] Such cyclic polyamines can be commercially obtained, or produced by transamination of cyclic amines as is generally known in the art. Examples of the high molecular weight, cyclic polyamines consistent with above Formula (I) that are useful in the present invention 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.

[0014] One preferred embodiment of the cyclic polyamine compound useful in preparing the composition of the present invention includes for example bis(2-(piperazin-1-yl)ethyl)amine (BPEA); high molecular weight BPEA oligomers; and mixtures thereof.The MWFs of the present invention comprise water, one or more base oils, one or more organic acids, one or more emulsifiers, one or more lubricants, one or more amines, where amines function as pH adjusters and / or microbial growth control agents, where the at least one amine comprises at least a cyclic polyamine of formula (I).

[0015] The microbial growth control agent may further comprise one or more additional antimicrobial materials such as glycol ether amines which may be used in combination with the above disclosed materials to achieve a certain microbial growth control targets. The concentration of the microbial growth control agent / pH adjuster in the MWF (including the cyclic polyamines s of formula (I)) may range from 1, 4, 6, 8. or 10 percent by weight of the formulation up to 30, 25, 15, or 12 percent of the formulation. Preferably the cyclic polyamines (s) of formula (I) comprise from 2, preferably 3, or even 5 percent up to 25, preferably 20 or even 15 percent by weight of the MWF.

[0016] The semi-synthetic MWFs of the present invention also include a base oil. The base oil can be any base oil generally known in the art for use in MWFs. Preferably the base oil is a base oil selected from tall oils, naphthenic oils, paraffinic oils or ester oils, or combinations thereof. The concentration of the base oil(s) in the MWF may range from 5, 7, 10, or 15 percent by weight of the formulation up to 50, 45. 40, or 35 percent of the formulation.

[0017] The water used in the present formulations is preferably deionized water, and may comprise from at least 20, preferably 25. 30, or even 35 percent by weight of the formulation up to a maximum of 70, 65, 60, 55 or even 50 percent by weight of the formulation. It is contemplated that these formulations may be further diluted with additional water prior to use, altering these ranges accordingly. For example, prior to use, the formulations may be diluted such that the base oil concentration is from 1 to 20 percent by weight of the diluted formulation, more typically 5 to 7 percent by weight.

[0018] The semi-synthetic MWFs of the present invention also include one or more organic acids as solubilizers and / or corrosion inhibitors. Preferred organic acids include 2-ethylhexoic acid, azelaic acid, toll oil fatty acid, 12-hydoxyl-(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 percent by weight of the formulation up to 12, 10. 8. or 7 percent of the formulation.

[0019] The semi-synthetic MWFs of the present invention also include one or more emulsifiers. The emulsifier may be anionic, cationic or nonionic. Examples of suitable anionic surfactants or emulsifiers are alkali metal, ammonium and amine soaps: the fatty acid part of such soaps contains preferably at least 10 carbon atoms. The soaps can also be formed "in situ;" in other words, a fatty acid can be added to the oil phase and an alkaline material to the aqueous phase.

[0020] Other examples of suitable anionic surfactants or emulsifiers are alkali metal salts of alkyl-aryl sulfonic acids, sodium dialkyl sulfosuccinate, sulfated or sulfonated oils, e.g., sulfated castor oil; sulfonated tallow, and alkali salts of short chain petroleum sulfonic acids.

[0021] Suitable cationic surfactants or emulsifiers are salts of long chain primary, secondary or tertiary amines, such as oleylamide acetate, acetylamine acetate, di-dodecylamine lactate, the acetate of aminoethyl-aminoethyl stearamide, dilauroyl triethylene tetramine diacetate, 1-aminoethyl-2-heptadecenyl imidazoline acetate: and quaternary salts, such as cetylpyridinium bromide, hexadecyl ethyl morpholinium chloride, and diethyl di-dodecyl ammonium chloride.

[0022] Examples of suitable nonionic surfactants or emulsifiers are condensation products of higher fatty alcohols with ethylene oxide, such as the reaction product of oleyl alcohol with 10 ethylene oxide units; condensation products of alkylphenols with ethylene oxide, such as the reaction product of isoctylphenol with 12 ethylene oxide units; condensation products of higher fatty acid amides with 5. or more, ethylene oxide units; polyethylene glycol esters of long chain fatty acids, such as tetraethylene glycol monopalmitate, hexaethyleneglycol monolaurate, nonaethyleneglycol monostearate, nonaethyleneglycol dioleate, tridecaethyleneglycol monoarachidate, tricosaethyleneglycol monobehenate, tricosaethyleneglycol dibehenate, polyhydric alcohol partial higher fatty acid esters such as sorbitan tristearate, ethylene oxide condensation products of polyhydric alcohol partial higher fatty acid esters, and their inner anhydrides (mannitol-anhydride, called Mannitan, and sorbitol-anhydride, called Sorbitan), such as 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, mannitan monopalmitate reacted with 10-15 molecules of ethylene oxide; long chain polyglycols in which one hydroxyl group is esterified with a higher fatty acid and other hydroxyl group is etherified with a low molecular alcohol, such as methoxypolyethylene glycol 550 monostearate (550 meaning the average molecular weight of the polyglycol ether). A combination of two or more of these surfactants may be used; e.g., a cationic may be blended with a nonionic or an anionic with a nonionic.

[0023] Particularly suitable emulsifiers include C16-18 alcohols which have been ethoxylated or propoxylated; ethoxylated C12-C15 alcohols; sodium alkane sulfonate and alky ether carboxylates.

[0024] The concentration of the emulsifier(s) in the MWF may range from 4, 5, 6, 8, or 10 percent by weight of the formulation up to 25, 20, 15, or 12 percent of the formulation.

[0025] The semi-synthetic MWFs of the present invention may also include one or more concentrate additives. If present, preferred concentrate additives include diethylene glycol butyl ether, ethylene glycol monobutyl ether, and propylene glycol butyl ether. If present, the concentration of the concentrate additive(s) in the MWF may range from 0.3, 0.5. 1.0, or 1.5 percent by weight of the formulation up to 2.5, 2.0, or 1.8 percent of the formulation.

[0026] The semi-synthetic MWFs of the present invention may also include other additives to provide additional functionality as generally known in the art.

[0027] The microbial growth controlled by the presently disclosed biocide typically consists of contaminations which are a bacterial and fungal mixture. Some typical fungi and bacterial 5 containments 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 10 (ATTC 2338). The strains listed above can vary around the world and the present innovation is fully envisioned as broad-spectrum microbial growth control agent and / or biocide which can be used against any common MWF microbial contaminates.EXAMPLES

[0028] Experiments to test the efficacy of formulations including the presently disclosed microbial growth control agent can be conducted as follows. Table 1 contains a description of the materials used in these examples. Table 1 - Diluted Metalworking Fluid IngredientsMaterial Type Source Mineral oilOily agentSCRCEcoSurf SA-7EmulsiferDowDowfax 20A42EmulsiferDowSecondary alkane sulphonateAnionic surfactantSCRCTall oil acidCorrosion agentSCRCSebacic acidCorrosion agentSCRCBis(piperazine ethyl) aminepH adjustorDowMonoisopropanolaminepH adjustorDowAMP-95 (2-amino-2-methyl-1-propanol)pH adjustorAngus ChemProcessing WaterWater containing common bacterial agents found in metal working processesN / ATap WaterWater containing 50 ppm metalN / AAluminum strip (#ADC12)MetalTCI A series of formulations is prepared according to Table 2. with the different amines listed in Table 3. Table 2 Material Concentrated Formulation Mineral oil12.5 wt.%EcoSurf SA-77.5 wt.%Dowfax 20A425.5 wt.%Secondary alkane sulphonate4.5 wt.%Tall oil acid4.5 wt.%Sebacic acid4.5 wt.%Amine (as indicated in Table 3)10.7 wt.%Water50.3 wt.% Table 3 Item Amine type Diluted water type Example 1 (IE1)Bis(piperazine ethyl) amineProcessing waterExample 2 (IE2)Bis(piperazine ethyl) amineTap waterExample 3 (IE3)Bis(piperazine ethyl) amineDeionized waterComparative Example 1 (CE1)MonoisopropanolamineProcessing waterComparative Example 2 (CE2)AMP-95Processing waterComparative Example 3 (CE3)DicyclohexylamineProcessing waterComparative Example 4 (CE4)MonoisopropanolamineTap waterComparative Example 5 (CE5)AMP-95Tap waterComparative Example 6 (CE6)DicyclohexylamineTap waterComparative Example 7 (CE7)MonoisopropanolamineDeionized water

[0029] The concentrated formulations are prepared as follows. The indicated amount of deionized water is poured into a container. Add mineral oil. EcoSurf SA-7, Dowfax 20A42, secondary alkane sulfonate, tall oil acid and diacid (sebacic acid) into the water. Stir the formulation by magnetic stirrer at 200 rpm at 60°C for 1 hour. Add the indicated amine as pH adjustor.

[0030] The concentrated formulations are then diluted by processing water or tap water or deionized water (as indicated in Table 3) by a factor of 20 times. based on the quantity of the whole concentrated formulation. Test pH value by pH titrator (Mettler Toledo: #SevenMulti). If pH value of the diluted formulation is below 9.5, introduce additional monoethanolamine (1-2 droplets) to increase pH value to at least 9.5.

[0031] pH aging test: test pH value by pH titrator (Mettler Toledo: #SevenMulti) of prepared diluted formulations for 0-day and 14-day. Samples are placed in ambient temperature. Table 4: pH aging test: Sample #Initial pH value1-week aging pH value2-week aging pH valuepH loss (%)IE19.549.439.43- 1.2%CE19.558.728.52- 10.8%CE29.549.299.29- 2.6%CE39.639.339.30- 3.4%

[0032] The pH decrement after 2-week aging should be as small as possible. IE1 with bis(piperazine ethyl) amine. CE2 & 3 with AMP-95 and dicyclohexylamine are in similar level which pH loss is controlled within 5%. CE1 with monoisopropanolamine is not good that pH loss exceeds 10%.

[0033] Aluminum corrosion test: Clean the Al strips (# ADC12) with alcohol and weigh strips. Immerse the Al strips into the test solution at 40°C for 48 hours with capped vials (a half volume of Al strip in solution and a half volume of Al strip exposed to air). Observe the corrosion of Al strip surface, measure weight loss of Al strips and use ICP-OES: inductively coupled plasma-optical emission spectrometer (Perkin Elmer: # Optima 5300DV) to detect Al content in formulations. Table 5: Aluminum corrosion test:Sample #CorrosionAluminum content by ICP-OESIE2< 1 ppmCE4< 1 ppmCE5< 1 ppmCE62.60 ppm

[0034] The ICP-OES data shows alignment with qualitative observation of aluminum strip corrosion. Larger area with yellow color demonstrates serious corrosion and higher aluminum content in test fluid. The qualitative description "pass", "marginal" or "fail" are added to comparatively describe the results observed. The ICP-OES data shows CE6 with dicyclohexylamine corroding over 1 ppm aluminum leaching from the strip. The outlook of sample CE6 is the worst with largest rust area. For other samples including IE1, CE4 & 5, there is < 1 ppm aluminum leaching from the strip.

[0035] pH value with antimicrobial test: Samples are operated under ASTM E 2275 method. This method can be summarized as follows: The inoculum is a mixture of ATCC strains of bacteria and fungi as set forth in Table 6. The Emulsion Products Mixed Inoculum is prepared by adding 0.1 mL of each bacterial overnight broth culture and 1.0 mL of each yeast broth culture to the 10 mL of mold suspension and blending.

[0036] 50 grams of sample are dosed with 0.5 ml of the mixed inoculum. This inoculation will challenge emulsion samples with a high level (106-107 Colony Forming Units per gram of sample, CFU / g) of microorganisms. Challenged samples are mixed and stored in the incubator at 30°C for seven days. This process is repeated for 5 additional rounds of testing with the following amounts of inoculum being added to each sample: 2nd round 0.5mL; 3rd round 1.0mL; 4th round 1.0mL; 5th round 3.0mL.The pH values of inoculated emulsion samples are tested at the end of the 5 weeks protocol and compared with the initial pH value of the emulsion before adding colony. Table 6 Microorganisms ATCC # Bacteria: Pseudomonas aeruginosa 10145Pseudomonas putida 12633Enterobacter aerogenes 13048Alcaligenes faecalis 25094Proteus hauseri 13315Burkholderia cepacia 21809Gluconacetobacter liquefaciens(Asai) 14835Gluconacetobacter liquefaciens 23751Yeast: Saccharomyces cerivisae 2338Candida lipolytica 18942Mold: Aspergillus niger 6275Penicillium ludwigii 9112 Table 7: Antimicrobial test: Sample #Initial pH value5-week pH value with microbeIE39.829.70CE79.769.46

[0037] IE3 with Bis(piperazine ethyl) amine shows only a 0.12 pH value decrement in antimicrobial evaluation. CE7 with monoisopropanolamine shows 0.30 pH value decrement in antimicrobial evaluation. Microbial stability of IE3 is therefore expected to be better than monoisopropanolamine when used in metal working fluid formulations.

Claims

1. A semi-synthetic metal working fluid, comprising: a. at least one base oil; b. at least one microbial growth control agent comprising an alkyl amine with the structure of: wherein each R, T, U, V, W, X, Y, and Z, in Formula (I) above, 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 as solubilizers and / or corrosion inhibitors, d. one or more emulsifiers, e. one or more concentrate additives, and f. water.

2. The semi-synthetic metal working fluid of claim 1, wherein each of R, T, U, V, W, X, Y, and Z in the microbial growth control agent is H.

3. The semi-synthetic metal working fluid of claim 1, wherein the microbial growth control agent is bis(2-(piperazin-1-yl)ethyl)amine (BPEA).

4. The semi-synthetic metal working fluid of claim 1, wherein the microbial growth control agent further comprises another amine.

5. The semi-synthetic metal working fluid of claim 1, wherein the base oil is selected from naphthenic oils, paraffinic oils, ester oils and mixtures thereof.

6. The semi-synthetic metal working fluid of claim 1, wherein the emulsifier is selected from C16-18 alcohols which have been ethoxylated or propoxylated, ethoxylated C12-C15 alcohols, sodium alkane sulfonate and alky ether carboxylates and mixtures thereof.

7. The semi-synthetic metal working fluid of claim 1, wherein the solubilizer / corrosion inhibitor is selected from ethylhexoic acid, azelaic acid, tall oil fatty acid, 12-hydoxyl-(cis)-9-octadecenoic acid, dicarboxylic acid, 9-octadecenoic acid, sebacic acid, and mixtures thereof.

8. The semi-synthetic metal working fluid of claim 1, wherein the concentrate additive is selected from diethylene glycol butyl ether, ethylene glycol monobutyl ether, propylene glycol butyl ether and mixtures thereof.

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

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

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

12. The semi-synthetic metal working fluid of claim 1, wherein the solubilizer / corrosion inhibitor is present in an amount of from 3 to 10 percent by weight of the semi-synthetic metal working fluid.

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