Aqueous semi-synthetic metalworking fluid compositions containing polyfunctional cyclic amines - Patent Application 20070233334

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 of controlling microbial growth in metalworking fluids comprising adding a particular class of multifunctional cyclic amines to the metalworking fluid. Other embodiments relate to semi-synthetic metalworking fluid compositions containing a microbial growth control agent comprising this particular class of multifunctional cyclic amines. [Background technology]

[0002] Introduction Metalworking fluids (MWFs) are used for lubrication during metal cutting and tool forming processes. These fluids help cool metalworking tools, remove cutting debris from the tool / workpiece interface, and provide acceptable post-machining finishes. Amines are common MWF components that are widely used in various applications due to their anti-corrosion, neutralizing, and pH adjusting properties. Organic amines are typically used as corrosion inhibitors because MWFs degrade over time due to microbial growth that negatively impacts fluid performance, and the microorganisms feed on the active ingredients in the fluid.

[0003] Such microbial growth in MWFs can cause serious problems in metalworking processes in many forms, including general pickling of the MWF, changes in the viscosity of the MWF, shortening of the shelf life of the MWF, and corrosion of tools and materials. In addition, the functionality of equipment and processes such as delivery nozzles, storage tanks, pipelines and recycling system equipment can also be affected by microbial growth in the MWF. This pickling increases the cost of the MWF, accelerates the corrosion rate and reduces the efficiency of metalworking. Thus, there is an unmet need in the MWF industry for components that do not support microbial growth and maintain performance over extended periods of time.

[0004] Thus, there is an unmet need in the MWF industry for components that do not support microbial growth and maintain performance over long periods of time. The most common solution is to add biocides and amine alcohols to a given MWF, either continuously or as a batch process. However, biocides and some secondary amine alcohols are restricted by regulatory restrictions, and most of the 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 fluids, or synthetic fluids, with each category exhibiting different functions of cooling, lubrication, rust prevention, and cleaning. Soluble oil MWFs contain 50-70 wt% neat oil, with the remainder of the MWF being antiwear / extreme pressure additives, and emulsifiers. Neat oil and soluble oil typically do not provide the same level of cooling compared to water-based metalworking fluids. Synthetic fluids typically cannot provide good lubrication performance because their lubrication function is affected by the back-dissolution of polyalkylene glycols when the temperature is higher than the cloud point. Semi-synthetic materials offer the possibility of simultaneously providing good lubrication and cooling properties for use in demanding applications. A typical semi-synthetic fluid consists of oil, organic acid, emulsifier, lubricant, amine, water, and other components. The amount of water in such semi-synthetic MWFs is typically up to 50-60% by weight, with about 10-40% by weight base oil, about 10-20% by weight emulsifier, about 10-20% by weight amine, and other functional additives such as acids, lubricants, solubilizers, biocides, etc. Semi-synthetic MWFs are usually diluted at the end user's site with additional water to a concentration of 1-20% by weight base oil, more typically 5-7% by weight, by weight of the diluted formulation.

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

[0007] Semi-synthetic fluids degrade partially over time due to microbial growth that adversely affects fluid performance as the microorganisms feed on the active ingredients in the fluid. Such microbial growth in MWFs can cause serious problems in metalworking processes in many forms, including general pickling of the MWF, viscosity changes of the MWF, shortening of the shelf life of the MWF, and corrosion of tools and materials. In addition, the functionality of equipment and processes such as delivery nozzles, storage tanks, pipelines and recycling system equipment can also be affected by microbial growth in the MWF. This pickling increases the cost of the 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 as a batch process. However, biocides and some secondary amine alcohols are limited by regulatory restrictions, and most of the biocidal chemicals release formaldehyde over time, which is harmful to human health.

[0008] Therefore, it would be desirable to have new semi-synthetic metalworking formulations with new biocidal compositions that provide improved cooling, lubricity, concentrate stability, and extended shelf life without the environmental health and safety concerns of current fluids.

[0009] The present invention addresses at least some of the needs set forth above. Summary of the Invention

[0010] The present invention relates to a method for controlling microbial growth in metalworking fluids, the method comprising adding at least one specific class of multifunctional 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, an additive concentrate, water, and a microbial growth control agent comprising a novel multifunctional cyclic amine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0012] The present invention relates to semi-synthetic metalworking fluids, and to novel materials which can be used as antimicrobial agents for use in such fluids. The materials of the present invention are polyfunctional cyclic amines corresponding to the following formula (I):

[0013] [ka] 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, with the value of x being 0 to 10. The hydrocarbyl groups that can be used in the practice of the present invention can be substituted (typically with N, O, or S atoms) or unsubstituted, and can be linear, branched, or cyclic hydrocarbyls such as alkyl, aryl, aralkyl, monovalent moieties containing one or more heteroatoms, polyether chains containing one or more oxyalkylene repeat units such as -RO-, where R is an alkylene of 2 to 5 carbon atoms, or other oligomeric or polymeric chains of at least two repeat units. In one embodiment, R, T, U, V, W, X, Y, and Z are H, or linear, branched, or cyclic hydrocarbyls 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 value of x in the practice 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 can be obtained commercially or prepared by transamination of cyclic amines as is generally known in the art. Examples of high molecular weight cyclic polyamines conforming to formula (I) above 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.

[0015] One preferred embodiment of a cyclic polyamine compound useful in preparing the compositions of the present invention includes, for example, bis(2-(piperazin-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, one or more amines, where the amines function as pH adjusters and / or microbial growth control agents, and at least one amine comprises at least a cyclic polyamine of formula (I).

[0016] 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 materials disclosed above to achieve a particular microbial growth control goal. The concentration of the microbial growth control agent / pH adjuster in the MWF (including the cyclic polyamine of formula (I)) may range from 1, 4, 6, 8, or 10 percent by weight of the formulation to 30, 25, 15, or 12 percent by weight of the formulation. Preferably, the cyclic polyamine(s) of formula (I) comprise 2, preferably 3, or even 5 percent by weight of the MWF to 25, preferably 20, or even 15 percent by weight.

[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 MWFs. Preferably, the base oil is a base oil selected from tall oil, naphthenic oil, paraffinic oil, or ester oil, or combinations thereof. The concentration of the base oil(s) in the MWF may range from 5, 7, 10, or 15 weight percent of the formulation to 50, 45, 40, or 35 percent of the formulation.

[0018] The water used in the present formulations is preferably deionized water and may comprise at least 20, preferably 25, 30, or even 35 weight percent of the formulation, up to 70, 65, 60, 55, or even 50 weight percent of the formulation. It is contemplated that these formulations may be further diluted with additional water prior to use, modifying these ranges accordingly. For example, prior to use, the formulations may be diluted such 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 includes one or more organic acids as solubilizers and / or corrosion inhibitors. Preferred organic acids include 2-ethylhexanoic acid, azelaic acid, tall oil fatty acid, 12-hydroxyl-(cis)-9-octadecenoic acid, dicarboxylic acid, and 9-octadecenoic acid. The concentration of the organic acid in the MWF can range from 2, 3, 4, or 5 weight percent of the formulation to 12, 10, 8, or 7 percent of the formulation.

[0020] The semi-synthetic MWF of the present invention also includes one or more emulsifiers. The emulsifiers can be anionic, cationic, or nonionic. Examples of suitable anionic surfactants or emulsifiers are alkali metal, 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, the fatty acid can be added to the oil phase and the alkaline material can be added to the water phase.

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

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

[0023] 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 isooctylphenol 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, hexaethylene glycol monolaurate, nonaethylene glycol monostearate, nonaethylene glycol dioleate, tridecaethylene glycol monoarachidate, tricosaethylene glycol monobehenate, and tricosaethylene glycol dibehenate; polyhydric alcohol moieties, such as sorbitan tristearate, and higher fatty acid esters. ethylene oxide condensation products of polyhydric alcohol partial higher fatty acid esters and their intramolecular anhydrides (called mannitol anhydride, mannitan, sorbitol anhydride, 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 to 15 molecules of ethylene oxide, mannitan monopalmitate reacted with 10 to 15 molecules of ethylene oxide, etc.; 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 (550 means the average molecular weight of the polyglycol ether). Combinations of two or more 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 C16-18 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 percent by weight of the formulation to 25, 20, 15, or 12 percent of the formulation.

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

[0028] The microbial growth controlled by the biocides of the present disclosure typically consists of contaminants that are a mixture of bacteria and fungi. Some exemplary fungal and bacterial5 inclusions 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 cerevisiae10 (ATTC 2338). The strains listed above may vary worldwide and the present invention is fully envisioned as a broad spectrum microbial growth control agent and / or biocide that can be used against any common MWF microbial contaminant. EXAMPLES

[0029] Experiments to test the effectiveness of formulations containing the microbial growth control agents of the present disclosure can be performed as follows: Table 1 contains a description of the materials used in these examples.

[0030] [Table 1]

[0031] A series of formulations are prepared according to Table 2 using different amines as listed in Table 3.

[0032] [Table 2]

[0033] [Table 3]

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

[0035] The concentrated formulation is then diluted 20 times based on the total volume of the concentrated formulation with process water or tap water or deionized water (as shown in Table 3). The pH value is tested with a pH titrator (Mettler Toledo: #SevenMulti). If the pH value of the diluted formulation is below 9.5, additional monoethanolamine (1-2 drops) is introduced to increase the pH value to at least 9.5.

[0036] pH aging test: The pH values ​​of the prepared diluted formulations are tested at 0 days and 14 days by a pH titrator (Mettler Toledo: #SevenMulti). The samples are placed at room temperature.

[0037] [Table 4]

[0038] The pH loss rate after 2 weeks of aging should be as small as possible. IE1 with bis(piperazineethyl)amine, CE2 and 3 with AMP-95 and dicyclohexylamine are at similar levels with pH loss controlled within 5%. CE1 with monoisopropanolamine is not as good in that the pH loss exceeds 10%.

[0039] Aluminum corrosion test: wash Al strip (#ADC12) with alcohol, weigh the strip. Immerse Al strip in test solution at 40°C for 48 hours using capped vial (half the volume of Al strip is in solution, half the volume of Al strip is exposed to air). Observe the corrosion of Al strip surface, measure the weight loss of Al strip, and use ICP-OES: Inductively Coupled Plasma Optical Emission Spectrometer (Perkin Elmer: #Optima 5300DV) to detect Al content in the formulation.

[0040] [Table 5]

[0041] The ICP-OES data shows agreement with the qualitative observations of aluminum strip corrosion. Larger areas with yellow color indicate more severe corrosion and higher aluminum content in the test fluid. A qualitative description of "pass", "marginal", or "fail" is added to relatively describe the observed results. The ICP-OES data shows CE6 having dicyclohexylamine corroding over 1 ppm of aluminum leaching from the strip. Sample CE6 has the poorest appearance and the largest area of ​​rust. For the other samples including IE1, CE4 and 5, less than 1 ppm of aluminum leaches from the strip.

[0042] pH value in antimicrobial test: The samples are run under the ASTM E 2275 method, which can be summarized as follows:

[0043] The inoculum is a mixture of ATCC strains of bacteria and fungi as 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.

[0044] Administer 0.5 mL of the mixed inoculum to 50 grams of sample. This inoculum challenges the emulsion samples with high levels (106-107 colony forming units per gram of sample, CFU / g) of microorganisms. The challenged samples are mixed and stored in an incubator at 30 °C for 7 days. This process is repeated for an additional 5 tests, adding the following amounts of inoculum to each sample: 2nd 0.5 mL, 3rd 1.0 mL, 4th 1.0 mL, 5th 3.0 mL. The pH values ​​of the inoculated emulsion samples are tested at the end of the 5-week protocol and compared to the initial pH value of the emulsion before the addition of the colonies.

[0045] [Table 6]

[0046] [Table 7]

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

Claims

1. 1. A semi-synthetic metalworking fluid comprising: a. at least one base oil; b. 【Chemistry 1】 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; and c. one or more organic acids; d. one or more emulsifiers; e. one or more additive concentrates; f. Water.

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

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

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

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

7. 2. The semi-synthetic metalworking fluid of claim 1, 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. 10. The semi-synthetic metalworking fluid of claim 1, wherein the additive concentrate is selected from diethylene glycol butyl ether, ethylene glycol monobutyl ether, propylene glycol butyl ether, and mixtures thereof.

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

12. 10. The semi-synthetic metalworking fluid of claim 1, 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 of 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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