Metalworking lubricant composition for copper and copper alloys

Abstract

To provide a lubricant composition that can suppress contamination of a processing machine and a processed material due to oxidative deterioration of an oily agent, and exhibit better processing performance than a conventional metal processing oil in processing a copper material and a copper alloy material.SOLUTION: A lubricant composition for copper and a copper alloy processing comprises polyalkylene glycol represented by a general formula (1) H-((O-CH2CH2CH2CH2)m / (O-CH2CH2)n)-OH (in the formula (1), m represents an integer of 1 to 60, and n represents an integer of 1 to 95).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to metalworking lubricant compositions for copper and copper alloys. [Background technology]

[0002] Conventionally, metalworking lubricants for copper-based metal materials used in metal cutting, grinding, or cutting, or plastic working such as extrusion, drawing, wire drawing, ironing, pressing, bending, roll forming, or drawing, have used mineral oils, fats and oils, esters, polyalkylene glycols, etc., for the purpose of imparting lubricity. Among these, fats and oils and esters have been used in applications requiring high lubricity because they have superior lubricating performance compared to mineral oils and polyalkylene glycols.

[0003] However, many fats, oils, and esters have oleic acid, which has a double bond, in their skeleton, and in this case, oxidative polymerization occurs, resulting in high viscosity and causing dirt to adhere to processing machines and processed objects. When processing machines and processed objects become dirty, this leads to a decrease in the quality of the processed objects and an increase in the labor required for cleaning the equipment. On the other hand, there are fats, oils, and esters that do not have double bonds and are less likely to undergo oxidative polymerization, but they are expensive and have poor lubricity.

[0004] When metalworking lubricants contain a large amount of fats and esters, their primary performance, lubricity, is improved, but secondary performance, such as the generation of metal soaps and discoloration, may be reduced. On the other hand, when metalworking lubricants contain a small amount of fats and esters, their secondary performance, such as resistance to deterioration, the suppression of discoloration and precipitate formation, and the resistance to contamination of processing machines and workpieces during application, is improved, but their primary performance, lubricity, is reduced. Improved primary performance extends the life of dies, tools, and molds, leading to reduced manufacturing costs and improved productivity. On the other hand, improved secondary performance improves product quality, reduces the frequency of processing oil changes and contamination in machine factories, leading not only to cost reductions but also to customer satisfaction and improved corporate image. Therefore, metalworking lubricants are required to achieve both primary and secondary performance.

[0005] Patent Document 1 discloses a lubricating oil for metalworking that uses polyalkylene glycol. The polyalkylene glycol has a weight-average molecular weight of 500 to 10,000, in which oxytetramethylene and oxyalkylene groups (excluding oxytetramethylene groups) are bonded randomly or in blocks, and has alkoxy groups at both ends. Patent Document 2 also discloses that a lubricating base oil containing, as an essential component, an alkylene oxide adduct of a diol with an HLB of 7.0 to 11.0 and a number-average molecular weight of 1,000 to 6,000 combines excellent water solubility and lubricity. Patent Document 3 discloses a cold rolling oil that contains a base oil and a nonionic surfactant in which oxybutylene and oxyethylene groups are bonded in blocks, and which has a terminal hydrogen atom and a residue of a compound having two or more active hydrogen atoms. Patent Document 4 discloses a lubricating oil for copper pipe drawing that has excellent lubricity during drawing and is capable of reducing residual oil without the need for forced removal of evaporated components by gas injection during annealing. The lubricating oil is composed of a polyoxypropylene glycol ether having an isopropyloxy group as a repeating unit and an average molecular weight of 2400 to 3000. Patent Document 5 also discloses a water-soluble metal plastic working oil composition that contains a base oil and an oxygen-containing compound that is at least one of an alkyl alcohol, an alkylene oxide adduct, a polyalkylene glycol, and an alkyl ether compound thereof, with the oxygen-containing compound content being 0.1 to 30 mass% of the entire composition.

[0006] Although various lubricants using polyalkylene glycols have been reported to date, there is a demand for metalworking lubricants that have better lubricity than conventional lubricants, suppress the adhesion of dirt to the processing machine and the workpiece, and improve secondary performance. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-12881 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-131982 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-18610 [Patent Document 4] Japanese Patent Application Publication No. 9-263780 [Patent Document 5] Japanese Patent Application Laid-Open No. 2005-220206 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a lubricating oil composition that suppresses contamination of processing machinery and workpieces due to oxidative degradation of oil agents and that can exhibit superior processing performance to conventional metal processing oils in processing copper and copper alloy materials. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that when polyalkylene glycols having oxyethylene and oxytetramethylene groups as repeating units are used in the processing of copper and copper alloys, it is possible to achieve lubricating performance that is far superior to that of conventional lubricating oils containing fats and oils or esters.

[0010] The present invention comprises the following items. The metalworking lubricating composition for copper and copper alloys of the present invention is characterized by containing a polyalkylene glycol represented by the following general formula (1).

[0011] H-((O-CH2CH2CH2CH2)m / (O-CH2CH2)n)-OH···(1) However, the weight average molecular weight (Mw) of the polyalkylene glycol of general formula (1) is preferably 500 to 5,000. The molecular weight ratio of the oxytetramethylene group in the polyalkylene glycol is preferably 20 to 80 wt %. In the general formula (1), m represents an integer of 1 to 60, and n represents an integer of 1 to 95. The content of the polyalkylene glycol is preferably 0.5% or more. [Effects of the Invention]

[0012] According to the present invention, by using a specific polyalkylene glycol having an oxyethylene group and an oxytetramethylene group as repeating units as a polyalkylene glycol with excellent oxidation stability, it is possible to provide a metalworking lubricating composition that has excellent lubricating performance and does not cause contamination of processing machines and workpieces. In other words, the specific polyalkylene glycol does not undergo high viscosity due to oxidation degradation, unlike oils and fats and esters. Therefore, the metalworking lubricating composition of the present invention can achieve both improved lubricity and suppressed fluid deterioration. [Brief explanation of the drawings]

[0013] [Figure 1] Figure 1 is a schematic diagram of a Bowden tester. [Figure 2] FIG. 2 is a graph showing the results of measuring the coefficient of friction by a Bowden test when the samples of Example 1, Comparative Example 8, and Comparative Example 10 were applied to various test plates (copper, aluminum, and iron). DETAILED DESCRIPTION OF THE INVENTION

[0014] The metalworking lubricating composition for copper and copper alloys of the present invention contains a polyalkylene glycol represented by the following general formula (1). H-((O-CH2CH2CH2CH2)m / (O-CH2CH2)n)-OH···(1) The metalworking lubricating composition for copper and copper alloys of the present invention (hereinafter simply referred to as "metalworking lubricating composition") is a water-soluble metalworking oil.

[0015] In the present invention, the copper and copper alloy workpieces refer to pure copper with a purity of 99.9% or more, and metallic materials such as brass, phosphor bronze, and brass, which contain copper as the main component and one or more of zinc, lead, aluminum, nickel, tin, etc.

[0016] The polyalkylene glycol represented by general formula (1) (hereinafter simply referred to as "polyalkylene glycol") contained in the metalworking lubricating composition functions as a lubricating component. The polyalkylene glycol used in the present invention does not undergo oxidative polymerization, nor does it become viscous or solidify, so it does not cause contamination of processing machines or workpieces.

[0017] The weight-average molecular weight (Mw) of the polyalkylene glycol represented by general formula (1) is preferably 500 to 5,000, more preferably 1,000 to 3,000. The weight-average molecular weight (Mw) is determined by gel permeation chromatography (GPC). If the weight-average molecular weight (Mw) of the polyalkylene glycol exceeds 5,000, it may become highly viscous and cause staining. On the other hand, if it is less than 500, the lubricity may decrease.

[0018] The molecular weight ratio of oxytetramethylene groups constituting the polyalkylene glycol is preferably 20 to 80 wt%, more preferably 40 to 70 wt%. On the other hand, the molecular weight ratio of oxyethylene groups constituting the polyalkylene glycol is preferably 80 to 20 wt%, more preferably 60 to 30 wt%. The molecular weight ratio is determined by NMR. The total molecular weight ratio of oxytetramethylene groups and oxyethylene groups is 100%. The oxytetramethylene groups and oxyethylene groups may be bonded randomly or in a block form.

[0019] In general formula (1), m and n are integers of 1 to 60 and 1 to 95, respectively. Preferably, the weight average molecular weight (Mw) of the polyalkylene glycol is 1000 to 3000 and the molecular weight ratio of the oxytetramethylene group is 40 to 70 wt %. In this case, m is preferably 5 to 30 and n is preferably 10 to 30.

[0020] The content of polyalkylene glycol in the lubricating composition for metalworking is 0.5% or more. By having a polyalkylene glycol content of 0.5% or more, the lubricity of the lubricating composition for metalworking can be improved.

[0021] In addition to the polyalkylene glycol, the metalworking lubricating composition may contain a nonionic surfactant, an anionic surfactant, an antioxidant, a non-ferrous metal corrosion inhibitor, water, and the like, within the scope of the object and effects of the present invention.

[0022] Examples of nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene fatty acid esters, and alkyl alcohols having 10 to 24 carbon atoms. These nonionic surfactants may be used alone or in combination of two or more.

[0023] Examples of anionic surfactants include petroleum sulfonates, fatty acid salts having 8 to 22 carbon atoms, and condensate salts of hydroxy fatty acids. Anionic surfactants function as emulsifiers in water-soluble metalworking fluids.

[0024] Examples of petroleum sulfonates include salts of alkylbenzenesulfonic acids with a molecular weight of 280 or more, such as mahogany acid. Salts constituting petroleum sulfonates include alkali metal salts, alkaline earth metal salts, and amine salts. Examples of the alkali metal salts include sodium salts. Examples of the alkaline earth metal salts include calcium salts and barium salts. Examples of the amine salts include primary to tertiary amine salts, diethanolamine salts, triethanolamine salts, diisopropanolamine salts, and triisopropanolamine salts.

[0025] The fatty acid may be either linear or branched. Examples of fatty acids having 8 to 22 carbon atoms include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and erucic acid. The term "salt of fatty acid having 8 to 22 carbon atoms" means that the fatty acid constituting the salt of fatty acid has 8 to 22 carbon atoms. Examples of salts constituting fatty acid salts include alkali metal salts and amine salts. Examples of the alkali metal salts include sodium salts and potassium salts. Examples of the amine salts include diethanolamine salts, triethanolamine salts, diisopropanolamine salts, and triisopropanolamine salts.

[0026] Examples of condensates of hydroxy fatty acids include condensates of ricinoleic acid. Examples of salts constituting the salts of condensates of hydroxy fatty acids include alkali metal salts and amine salts. Examples of the alkali metal salts include sodium salts and potassium salts. Examples of the amine salts include diethanolamine salts, triethanolamine salts, diisopropanolamine salts, and triisopropanolamine salts. These anionic surfactants may be contained alone or in combination of two or more.

[0027] Examples of antioxidants include phenol-based antioxidants (e.g., 2,4-dimethyl-6-tert-butylphenol and 4,4-butylidenebis(6-tert-butylmetacresol)), amine-based antioxidants (e.g., phenyl-α-naphthylamine and phenyl-β-naphthylamine), zinc dialkyldithiophosphate having 1 to 36 carbon atoms, zinc diallyldithiophosphate having 2 to 36 carbon atoms, organic sulfides, and organic selenides. These antioxidants may be used alone or in combination of two or more.

[0028] Examples of the non-ferrous metal corrosion inhibitor include benzotriazole, tolyltriazole, mercaptobenzothiazole, etc. These non-ferrous metal corrosion inhibitors may be used alone or in combination of two or more.

[0029] As the water, for example, distilled water, ion-exchanged water, and tap water can be used. The lubricating composition for metalworking may be diluted with water at any ratio before use.

[0030] In addition, the metalworking lubricating composition may contain lubricating components such as fatty acids, esters, and mineral oils, as well as extreme pressure additives. Furthermore, a solubilizer may be added to improve the stability of the metalworking lubricating composition.

[0031] The lubricating composition for metalworking can be produced by adding a nonionic surfactant, an anionic surfactant, an antioxidant, a non-ferrous metal corrosion inhibitor, and water, as needed, to the polyalkylene glycol represented by general formula (1), and mixing and stirring until homogeneous to obtain a dispersion.

[0032] The lubricating components in the metalworking lubricating composition are not subject to oxidative degradation and have excellent thermal stability. In the present invention, the degradation resistance is determined by measuring the kinematic viscosity (in accordance with JIS K 2283) of the lubricating components in the metalworking lubricating composition at 40°C, allowing the composition to stand at 70°C, and then measuring it again, and calculating the viscosity increase rate from the viscosities before and after heating.

[0033] The metalworking lubricating composition has excellent lubricity. The lubricity is evaluated using a Bowden tester, as shown in Figure 1. That is, a small amount of the metalworking lubricating composition 1 is dropped onto a test plate 2 placed on a support 3, a steel ball 5 is pressed against it with a constant load W, and the test plate 2 is slid at a constant sliding speed. The friction force P acting on the steel ball 5 is detected with a strain gauge, and the friction coefficient μ is calculated using the formula μ = P / W. In the present invention, the lubricity is determined as the average friction coefficient after 20 sliding movements over a distance of 25 mm.

[0034] The metalworking lubricating composition can be widely used as a lubricant for cutting, drawing, wire drawing, pressing, drawing, ironing, bending, rolling, cold forging, and other processes. [Example]

[0035] EXAMPLES The present invention will be explained in more detail below based on examples and comparative examples, but the present invention is not limited to these examples. [Evaluation of lubricant compositions for metalworking]

[0036] (1) Lubricity (coefficient of friction) The metalworking lubricating compositions of Examples 1 to 3 and Comparative Examples 1 to 11 (hereinafter referred to as "compositions") were diluted with water to 10% to prepare evaluation samples. The lubricity of each sample was evaluated by a Bowden test. Specifically, the sample was applied to a test plate, and a steel ball was pressed against it with a constant load (applied load W), and the plate was subjected to a reciprocating motion at a sliding speed V. During this time, the friction force P acting on the steel ball was detected with a strain gauge, and the friction coefficient μ was calculated using the formula μ = P / W. An overview of the testing machine is shown in Figure 1, and the test conditions are shown in Table 1. [Table 1] The results are shown in Tables 2 and 3. The lower the friction coefficient, the better the lubricant performance. A friction coefficient of less than 0.12 was judged as good (◯), 0.12 to 0.14 was judged as generally good (△), and over 0.14 was judged as problematic (×).

[0037] (2) Deterioration resistance A predetermined amount of the raw material described in Example 4 and Comparative Examples 12 to 14 was placed in a Cannon-Fenske viscometer, and the time it took for the raw material to flow through the capillary tube was measured to calculate the kinematic viscosity. The raw material was then left to stand at 70°C for 24 hours, after which the kinematic viscosity was calculated in the same manner, and the viscosity increase rate was calculated from the kinematic viscosity before and after heating. The kinematic viscosity was measured in accordance with JIS K 2283. The results are shown in Table 4. The lower the thickening rate, the better the deterioration resistance. A thickening rate of less than 10% was judged as good (◯), 10 to 20% was judged as generally good (△), and more than 20% was judged as problematic (×). [Preparation of Lubricating Composition for Metalworking]

[0038] [Sample for lubricity evaluation] [Example 1] A lubricating composition for metalworking was prepared by mixing 30.3 parts by mass of polyalkylene glycol represented by general formula (1) (Mw 1100, 55% oxyethylene group + 45% oxytetramethylene group, structure: random copolymer) with 3.6 parts by mass of triethanolamine, 22.8 parts by mass of sodium petroleum sulfonate, 4.6 parts by mass of ricinoleic acid condensation amide, 8.3 parts by mass of nonionic surfactant, 6.1 parts by mass of higher alcohol, 1.5 parts by mass of glycol-based solvent, and 22.8 parts by mass of water. The friction coefficient μ was 0.112. Table 2 shows the properties of the polyalkylene glycols used and the evaluation results of the lubricating compositions for metalworking.

[0039] [Example 2] A lubricating composition for metalworking was prepared in the same manner as in Example 1, except that in Example 1, polyalkylene glycol (weight average molecular weight (Mw) 2000, 35% oxyethylene group + 65% oxytetramethylene group, structure: random copolymer) was used instead of the polyalkylene glycol represented by general formula (1). The friction coefficient μ was 0.110. Table 2 shows the properties of the polyalkylene glycols used and the evaluation results of the lubricating compositions for metalworking.

[0040] [Example 3] A metalworking lubricating composition was prepared in the same manner as in Example 1, except that in Example 1, polyalkylene glycol (Mw 3000, 35% oxyethylene group + 65% oxytetramethylene group, structure: random copolymer) was used instead of the polyalkylene glycol represented by general formula (1). The friction coefficient μ was 0.107. Table 2 shows the properties of the polyalkylene glycols used and the evaluation results of the lubricating compositions for metalworking.

[0041] [Comparative Example 1] A lubricating composition was prepared in the same manner as in Example 1, except that a polyalkylene glycol (Mw 1000, 50% oxypropylene group + 50% oxytetramethylene group) was used instead of the polyalkylene glycol represented by general formula (1) in Example 1. The friction coefficient μ was 0.140. The properties of the polyalkylene glycol used and the evaluation results of the lubricating composition are shown in Table 2.

[0042] Comparative Example 2 A lubricating composition was prepared in the same manner as in Example 1, except that a polyalkylene glycol (Mw 2000, 35% oxypropylene group + 65% oxytetramethylene group) was used instead of the polyalkylene glycol represented by general formula (1) in Example 1. The friction coefficient μ was 0.146. The properties of the polyalkylene glycol used and the evaluation results of the lubricating composition are shown in Table 2.

[0043] Comparative Example 3 A lubricating composition was prepared in the same manner as in Example 1, except that a polyalkylene glycol (Mw 980, containing an oxyethylene group and an oxybutylene group) was used instead of the polyalkylene glycol represented by the general formula (1) in Example 1. The friction coefficient μ was 0.146. The properties of the polyalkylene glycol used and the evaluation results of the lubricating composition are shown in Table 2.

[0044] Comparative Example 4 A lubricating composition was prepared in the same manner as in Example 1, except that in Example 1, polyalkylene glycol (Mw 2000, 15% oxyethylene group + 85% oxypropylene group, structure: block copolymer) was used instead of the polyalkylene glycol represented by general formula (1). The friction coefficient μ was 0.149. The properties of the polyalkylene glycol used and the evaluation results of the lubricating composition are shown in Table 2.

[0045] Comparative Example 5 A lubricating composition was prepared in the same manner as in Example 1, except that in Example 1, polyalkylene glycol (Mw 2000, 25% oxyethylene group + 75% oxypropylene group, structure: reverse block copolymer) was used instead of the polyalkylene glycol represented by general formula (1). The friction coefficient μ was 0.149. The properties of the polyalkylene glycol used and the evaluation results of the lubricating composition are shown in Table 2.

[0046] Comparative Example 6 A lubricating composition was prepared in the same manner as in Example 1, except that in Example 1, polyalkylene glycol (polyethylene glycol, Mw 2000, 100% oxyethylene group) was used instead of the polyalkylene glycol represented by general formula (1). The friction coefficient μ was 0.147. The properties of the polyalkylene glycol used and the evaluation results of the lubricating composition are shown in Table 3.

[0047] Comparative Example 7 A lubricating composition was prepared in the same manner as in Example 1, except that in Example 1, polyalkylene glycol (polypropylene glycol, Mw 2000, 100% oxypropylene group) was used instead of the polyalkylene glycol represented by general formula (1). The friction coefficient μ was 0.153. The properties of the polyalkylene glycol used and the evaluation results of the lubricating composition are shown in Table 3.

[0048] [Comparative Example 8] A lubricating composition was prepared in the same manner as in Example 1, except that an ester (2-ethylhexyl oleate) was used instead of the polyalkylene glycol. The friction coefficient μ was 0.130. The evaluation results of the ester lubricating compositions are shown in Table 3.

[0049] Comparative Example 9 A lubricating composition was prepared in the same manner as in Example 1, except that an ester (trimethylolpropane trioleate) was used instead of the polyalkylene glycol. The friction coefficient μ was 0.133. The evaluation results of the ester lubricating compositions are shown in Table 3.

[0050] [Comparative Example 10] A lubricating composition was prepared in the same manner as in Example 1, except that mineral oil (equivalent to machine oil) was used instead of the polyalkylene glycol. The friction coefficient μ was 0.144. The evaluation results of the mineral oil lubricating compositions are shown in Table 3.

[0051] [Comparative Example 11] A lubricating composition was prepared in the same manner as in Example 1, except that mineral oil (equivalent to spindle oil) was used instead of the polyalkylene glycol. The friction coefficient μ was 0.146. The evaluation results of the mineral oil lubricating compositions are shown in Table 3. The lubricating compositions of Comparative Examples 1 to 11 did not satisfy the lubrication performance requirements.

[0052] [Samples for evaluating deterioration resistance] [Example 4] When polyalkylene glycol (Mw 1100, 55% oxyethylene group + 45% oxytetramethylene group) was evaluated as a sample, the viscosity increase rate was less than 1%. The evaluation results of the polyalkylene glycols used are shown in Table 4.

[0053] [Comparative Example 12] When the ester (2-ethylhexyl oleate) was evaluated as a sample, the viscosity increase rate was 23%. The evaluation results of the esters used are shown in Table 4.

[0054] [Comparative Example 13] When an ester (trimethylolpropane trioleate) was evaluated as a sample, the viscosity increase rate was 37%. The evaluation results of the esters used are shown in Table 4.

[0055] [Comparative Example 14] When mineral oil (equivalent to machine oil) was used as a sample for evaluation, the viscosity increase rate was 2%. The evaluation results of the mineral oils used are shown in Table 4.

[0056] [Table 2]

[0057] [Table 3]

[0058] [Table 4]

[0059] [Lubricity evaluation test] The metalworking lubricating compositions of Example 1, Comparative Example 8, and Comparative Example 10 were applied to aluminum (A1050) and iron (SPCC-SB), and the friction coefficients were measured by a Bowden test. The lubricity was evaluated by comparing it with that when copper (C1100) was used as the test plate. The results are shown in Table 5. Figure 2 shows a graph in which the friction coefficients in Table 5 are plotted on the vertical axis. When applied to iron (SPCC-SB) and tested, the friction coefficient of Example 1 was equivalent to that of Comparative Example 8. Furthermore, when applied to aluminum (A1050) and tested, the friction coefficient of Example 1 was higher than that of Comparative Example 8, with Comparative Example 8 showing the best lubricity. When applied to copper (C1100) and tested, Example 1, which used polyalkylene glycol, showed the best lubricity. The metalworking lubricating composition of the present invention was found to have the effect of significantly reducing the friction coefficient in copper and copper alloys. Therefore, it is clear that it is suitable for machining copper and copper alloys.

[0060] [Table 5] [Explanation of symbols]

[0061] 1 Lubricating composition for metal processing 2 test plates 3 Support stand 4 cylindrical rods 5 steel ball

Claims

[Claim 1] It contains a polyalkylene glycol represented by the following general formula (1): The content of the polyalkylene glycol is 0.5% by mass or more and 30.3% by mass or less, the molecular weight ratio of oxytetramethylene groups constituting the polyalkylene glycol is 45% by mass or more and 65% by mass or less, the molecular weight ratio of oxyethylene groups constituting the polyalkylene glycol is 35% by mass or more and 55% by mass or less; A metalworking lubricating composition for copper and copper alloys, characterized in that the weight average molecular weight of the polyalkylene glycol is 1,100 or more and 3,000 or less. H-((O-CH 2 CH 2 CH 2 CH 2 )m / (O-CH 2 CH 2 )n)-OH・・・(1) (In general formula (1), m represents an integer of 1 to 60, and n represents an integer of 1 to 95.)

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