WATER-SOLUBLE METAL PROCESSING OIL COMPOSITION

Abstract

The present invention provides a water-soluble metalworking oil composition, including: 5.0 to 20.0 mass % of a sulfur compound (A) that is one or more kinds selected from the group consisting of a sulfurized fat and oil and a sulfurized ester and has a kinematic viscosity of 10 to 800 mm.sup.2/s at 40° C.; 0.5 to 20.0 mass % of the nonionic surfactant (B) having an HLB of 6 to 18; 7.0 to 30.0 mass % of an unsaturated fatty acid polymer (C); and an amine compound (D) selected from the group consisting of a tertiary amine and a secondary amine.

Claims

1. A water-soluble metalworking oil composition, comprising: 5.0 to 20.0 mass % of a sulfur compound (A) that is at least one selected from the group consisting of a sulfurized fat and oil and a sulfurized ester and has a kinematic viscosity at 40° C. of 10 to 800 mm.sup.2/s; 0.5 to 20.0 mass % of a nonionic surfactant (B) having an HLB of 6 to 18; 7.0 to 30.0 mass % of an unsaturated fatty acid polymer (C); and an amine compound (D) selected from the group consisting of a tertiary amine and a secondary amine.

2. The water-soluble metalworking oil composition according to claim 1, wherein the component (B) is a polyoxyalkylene alkyl ether (B1) having an alkyl group having 4 to 24 carbon atoms.

3. The water-soluble metalworking oil composition according to claim 1, wherein a content ratio of the component (B) to the component (A), that is, [(B)/(A)] is 0.21 to 1.50 in terms of a mass ratio.

4. The water-soluble metalworking oil composition according to claim 1, wherein a content ratio of the component (C) to the component (A), that is, [(C)/(A)] is 0.90 to 5.00 in terms of a mass ratio.

5. The water-soluble metalworking oil composition according to claim 1, wherein a content ratio of the component (C) to the component (B), that is, [(C)/(B)] is 1.20 to 6.90 in terms of a mass ratio.

6. The water-soluble metalworking oil composition according to claim 1, wherein a content of the component (D) is 5.0 to 40.0 mass % based on a total amount of the water-soluble metalworking oil composition.

7. The water-soluble metalworking oil composition according to claim 1, wherein a content ratio of the component (D) to the component (A), that is, [(D)/(A)] is 1.10 to 6.00 in terms of a mass ratio.

8. The water-soluble metalworking oil composition according to claim 1, wherein a content ratio of the component (D) to the component (B), that is, [(D)/(B)] is 1.0 to 15.0 in terms of a mass ratio.

9. The water-soluble metalworking oil composition according to claim 1, wherein a content ratio of the component (D) to the component (C), that is, [(D)/(C)] is 0.80 to 3.50 in terms of a mass ratio.

10. The water-soluble metalworking oil composition according to claim 1, wherein a ratio of a base number to an acid value of the water-soluble metalworking oil composition, that is [base number/acid value] is 1.0 to 3.0.

11. The water-soluble metalworking oil composition according to claim 1, which is used for processing a workpiece made of a metal selected from the group consisting of titanium, a titanium alloy, alloy steel, a nickel base alloy, a niobium alloy, a tantalum alloy, a molybdenum alloy, a tungsten alloy, stainless steel, and high manganese steel.

12. A metalworking fluid obtained by diluting the water-soluble metalworking oil composition according to claim 1 with the addition of dilution water.

13. The metalworking fluid according to claim 12, wherein the dilution water has a hardness of 0 to 800.

14. The metalworking fluid according to claim 12, wherein the metalworking fluid is obtained by diluting the water-soluble metalworking oil composition with the addition of dilution water to have a dilution concentration of 1 to 50 vol %.

15. A metalworking method for processing a workpiece made of a metal using the metalworking fluid according to claim 12.

Description

EXAMPLES

[0198] Next, the present invention is described in more detail with reference to Examples, but the present invention is not limited by these Examples. Measurement methods of various physical properties are as follows.

[0199] (1) Kinematic Viscosity

[0200] Measurement was performed in accordance with JIS K2283: 2000.

[0201] (2) Sulfur Atom Content

[0202] Measurement was performed in accordance with JIS K2541-6: 2013.

[0203] (3) HLB

[0204] Calculation was performed by a Griffin method.

[0205] (4) Acid Value

[0206] Measurement was performed in accordance with JIS K2501: 2003 (indicator photometric titration method).

[0207] (5) Base Number

[0208] Measurement was performed in accordance with JIS K2501: 2003 (perchloric acid method).

[0209] (6) Saponification Value

[0210] Measurement was performed in accordance with JIS K2503: 1996.

[0211] (7) Hydroxyl Value

[0212] Measurement was performed in accordance with JIS K0070: 1992.

[0213] In addition, the details of each component used for the preparation of the water-soluble metalworking oil composition in the following Examples and Comparative Examples are as follows.

[0214] <Sulfur Compound> [0215] Sulfurized fat and oil (a-i): sulfurized fat and oil having a kinematic viscosity at 40° C. of 55.0 mm.sup.2/s and a sulfur atom content of 17.5 mass % [0216] Sulfurized fat and oil (a-ii): sulfurized fat and oil having a kinematic viscosity at 40° C. of 381.7 mm.sup.2/s and a sulfur atom content of 10.4 mass % [0217] Sulfurized fat and oil (a-iii): sulfurized fat and oil having a kinematic viscosity at 40° C. of 900.0 mm.sup.2/s and a sulfur atom content of 11.6 mass % [0218] Sulfurized olefin (a-iv): sulfurized olefin having a sulfur chain length of 5, a kinematic viscosity at 40° C. of 45.0 mm.sup.2/s, a sulfur atom content of 39.0 mass %.

[0219] <Nonionic Surfactant> [0220] POA alkyl ether (b-i): polyoxyethylene-polyoxypropylene alkyl ether having an alkyl group having 10 to 13 carbon atoms, HLB=12.7. [0221] POA alkyl ether (b-ii): polyoxyethylene-polyoxypropylene alkyl ether having an alkyl group having 12 carbon atoms, HLB=14.0. [0222] POA alkyl ether (b-iii): polyoxyethylene-polyoxypropylene alkyl ether having an alkyl group having 12 carbon atoms, HLB=3.0.

[0223] <Unsaturated Fatty Acid Polymer> [0224] Polymerized fatty acid (c-i): A polymerized fatty acid obtained by thermal dehydration condensation of ricinoleic acid at 200° C. under a nitrogen stream Acid value=52 mgKOH/g, saponification value=196 mgKOH/g, hydroxyl value: 20 mgKOH/g [0225] Polymerized fatty acid (c-ii): A polymerized fatty acid obtained by thermal dehydration condensation of ricinoleic acid at 200° C. under a nitrogen stream, further adding lauric acid, and thermal dehydration condensation Acid value=85 mgKOH/g, saponification value=200 mgKOH/g, hydroxyl value: 9 mgKOH/g

[0226] <Amine Compound> [0227] Tertiary amine (d-i): cyclohexyldiethanolamine [0228] Tertiary amine (d-ii): N-methyldicyclohexylamine [0229] Primary amine (d′): monoisopropanolamine

[0230] <Carboxylic Acid Component> [0231] Tall oil fatty acid: unsaturated monocarboxylic acid mainly composed of oleic acid, linoleic acid or the like [0232] Neodecanoic acid: saturated aliphatic monocarboxylic acid [0233] Dodecanedioic acid: saturated aliphatic dicarboxylic acid

[0234] <Other Components> [0235] Benzotriazole [0236] Methyl oleate: kinematic viscosity at 40° C.=4.7 mm.sup.2/s [0237] Water

Examples 1 to 10, Comparative Examples 1 to 10

[0238] Sulfur compounds, nonionic surfactants, unsaturated fatty acid polymers, amine compounds, carboxylic acid components, and other components were mixed in the kinds and blending amounts shown in Tables 1 and 2 to prepare water-soluble metalworking oil compositions, respectively.

[0239] The acid value and the base number of the prepared water-soluble metalworking oil composition were measured, and the following evaluations were performed. These results are shown in Tables 1 and 2.

[0240] (1) Processability

[0241] The water-soluble metalworking oil compositions obtained in Examples and Comparative Examples were diluted with water to prepare a metalworking fluid having a dilution concentration of 5% by volume. Rolled tapping processing was performed under the following conditions using the prepared metalworking fluid, and the average tap torque at the time of processing was measured. The average tap torque was measured 3 times, the average value thereof was calculated, and when the average tap torque value was 260 N.Math.cm or less, it was determined that the metalworking oil has good processability. It can be said that the smaller the value of the average tap torque, the better the processability of the metalworking oil.

[0242] (Rolled Tapping Processing Conditions) [0243] Processing machine used: Megatap II (microtap GmbH) [0244] Tool: Nu-Roll Tap VP-NRT B M6X1 (OSG) (manufactured by OSG Corporation) [0245] Processing speed (tap peripheral speed): 10 m/min [0246] Processing depth (processing distance): 10 mm [0247] Workpiece material: SCM440 [0248] Pilot hole diameter: 5.52 mm

[0249] (2) Self-Emulsifiability

[0250] To a 100 mL measuring cylinder containing 95 mL of water, 5 mL of the water-soluble metalworking oil composition obtained in Examples and Comparative Examples was added and the measuring cylinder was turned over 10 times in the vertical direction, then the liquid in the measuring cylinder was visually observed, and the self-emulsifiability was evaluated based on the following criteria.

[0251] A: The water-soluble metalworking oil composition is uniformly dissolved with water.

[0252] F: Solubility residue of the water-soluble metalworking oil composition is partially observed.

[0253] (3) Hard Water Stability

[0254] A sample solution having a dilution concentration of 5% by volume was prepared using water prepared to have a hardness of 500 with Mg ions and the water-soluble metalworking oil compositions obtained in Examples and Comparative Examples. Then, the sample solution was visually observed, and the hard water stability was evaluated based on the following criteria.

[0255] A: The sample solution is in a uniform state.

[0256] F: Separation or precipitation occurs in the sample solution.

TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Composition sulfur Sulfurized fat and oil (a-i) mass % 12.5 — 17.5 7.0 12.5 compound Sulfurized fat and oil (a-ii) mass % — 12.5 — — — Sulfurized fat and oil (a-iii) mass % — — — — — Nonionic POA alkyl ether (b-i), HLB = 12.7 mass % 5.0 5.0 5.0 5.0 surfactant POA alkyl ether (b-ii), HLB = 14.0 mass % — — — — 5.0 POA alkyl ether (b-iii), HLB = 3.0 mass % — — — — — Unsaturated Polymerized fatty acid (c-i) mass % 20.0 20.0 20.0 20.0 20.0 fatty acid Polymerized fatty acid (c-ii) mass % — — — — — polymer Amine Tertiary amine (d-i) mass % 18.5 18.5 18.5 18.5 18.5 compound Tertiary amine (d-ii) mass % 5.5 5.5 5.5 5.5 5.5 Primary amine (d-iii) mass % — — — — — Carboxylic Tall oil fatty acid mass % 2.0 2.0 2.0 2.0 2.0 acid Neodecanoic acid mass % 4.3 4.3 4.3 4.3 4.3 component Dodecanedioic acid mass % 1.0 1.0 1.0 1.0 1.0 Other Benzotriazole mass % 1.0 1.0 1.0 1.0 1.0 components Methyl oleate mass % 12.0 12.0 7.0 17.5 12.0 Water mass % 18.2 18.2 18.2 18.2 18.2 Total mass % 100.0 100.0 100.0 100.0 100.0 Content Nonionic surfactant/Sulfur compound (mass ratio) 0.40 0.40 0.29 0.71 0.40 ratio of two Unsaturated fatty acid polymer/Sulfur compound (mass ratio) 1.60 1.60 1.14 2.86 1.60 components Amine compound/Sulfur compound (mass ratio) 1.92 1.92 1.37 3.43 1.92 Unsaturated fatty acid polymer/Nonionic surfactant (mass ratio) 4.00 4.00 4.00 4.00 4.00 Amine compound/Nonionic surfactant (mass ratio) 4.80 4.80 4.80 4.80 4.80 Amine compound/Unsaturated fatty acid polymer (mass ratio) 1.20 1.20 1.20 1.20 1.20 Properties Acid value mgKOH/g 38.2 38.2 38.2 38.2 38.2 Base number mgKOH/g 70.7 70.7 70.7 70.7 70.7 Base number/Acid value — 1.8 1.8 1.8 1.8 1.8 Sulfur atom content mass % 2.19 1.30 3.06 1.23 2.19 Evaluations Processability: Average tap torque N .Math. cm 239 230 231 251 240 Self-emulsifiability — A A A A A Hard water stability — A A A A A Example 6 Example 7 Example 8 Example 9 Example 10 Composition sulfur Sulfurized fat and oil (a-i) mass % 12.5 12.5 12.5 12.5 12.5 compound Sulfurized fat and oil (a-ii) mass % — — — — — Sulfurized fat and oil (a-iii) mass % — — — — — Nonionic POA alkyl ether (b-i), HLB = 12.7 mass % 3.0 10.0 5.0 5.0 5.0 surfactant POA alkyl ether (b-ii), HLB = 14.0 mass % — — — — — POA alkyl ether (b-iii), HLB = 3.0 mass % — — — — — Unsaturated Polymerized fatty acid (c-i) mass % 20.0 20.0 — 25.0 15.0 fatty acid Polymerized fatty acid (c-ii) mass % — — 20.0 — — polymer Amine Tertiary amine (d-i) mass % 18.5 18.5 18.5 18.5 18.5 compound Tertiary amine (d-ii) mass % 5.5 5.5 5.5 5.5 5.5 Primary amine (d-iii) mass % — — — — — Carboxylic Tall oil fatty acid mass % 2.0 2.0 2.0 2.0 2.0 acid Neodecanoic acid mass % 4.3 4.3 4.3 4.3 4.3 component Dodecanedioic acid mass % 1.0 1.0 1.0 1.0 1.0 Other Benzotriazole mass % 1.0 1.0 1.0 1.0 1.0 components Methyl oleate mass % 12.0 12.0 12.0 12.0 12.0 Water mass % 20.2 13.2 18.2 13.2 23.2 Total mass % 100.0 100.0 100.0 100.0 100.0 Content Nonionic surfactant/Sulfur compound (mass ratio) 0.24 0.80 0.40 0.40 0.40 ratio of two Unsaturated fatty acid polymer/Sulfur compound (mass ratio) 1.60 1.60 1.60 2.00 1.20 components Amine compound/Sulfur compound (mass ratio) 1.92 1.92 1.92 1.92 1.92 Unsaturated fatty acid polymer/Nonionic surfactant (mass ratio) 6.67 2.00 4.00 5.00 3.00 Amine compound/Nonionic surfactant (mass ratio) 8.00 2.40 4.80 4.80 4.80 Amine compound/Unsaturated fatty acid polymer (mass ratio) 1.20 1.20 1.20 0.96 1.60 Properties Acid value mgKOH/g 38.2 38.2 44.8 40.8 35.6 Base number mgKOH/g 70.7 70.7 70.7 70.7 70.7 Base number/Acid value — 1.8 1.8 1.6 1.7 2.0 Sulfur atom content mass % 2.19 2.19 2.19 2.19 2.19 Evaluations Processability: Average tap torque N .Math. cm 238 242 255 235 248 Self-emulsifiability — A A A A A Hard water stability — A A A A A

TABLE-US-00002 TABLE 2 Compar- Compar- Compar- Compar- Compar- ative ative ative ative ative Example 1 Example 2 Example 3 Example 4 Example 5 Composition Sulfur Sulfurized fat and oil (a-i) mass % — — 3.0 25.0 12.5 compound Sulfurized fat and oil (a-ii) mass % — — — — — Sulfurized fat and oil (a-iii) mass % — 12.5 — — — Nonionic POA alkyl ether (b-i), HLB = 12.7 mass % 5.0 5.0 5.0 5.0 0.3 surfactant POA alkyl ether (b-ii), HLB = 14.0 mass % — — — — — POA alkyl ether (b-iii), HLB = 3.0 mass % — — — — — Unsaturated Polymerized fatty acid (c-i) mass % 20.0 20.0 20.0 20.0 20.0 fatty acid Polymerized fatty acid (c-ii) mass % — — — — — polymer Amine Tertiary amine (d-i) mass % 18.5 18.5 18.5 18.5 18.5 compound Tertiary amine (d-ii) mass % 5.5 5.5 5.5 5.5 5.5 Primary amine (d-iii) mass % — — — — — Carboxylic Tall oil fatty acid mass % 2.0 2.0 2.0 2.0 2.0 acid Neodecanoic acid mass % 4.3 4.3 4.3 4.3 4.3 component Dodecanedioic acid mass % 1.0 1.0 1.0 1.0 1.0 Other Benzotriazole mass % 1.0 1.0 1.0 1.0 1.0 components Methyl oleate mass % 24.5 12.0 21.5 — 12.0 Water mass % 18.2 18.2 18.2 17.7 22.9 Total mass % 100.0 100.0 100.0 100.0 100.0 Content Nonionic surfactant/Sulfur compound (mass ratio) — 0.40 1.67 0.20 0.02 ratio of two Unsaturated fatty acid polymer/Sulfur compound (mass ratio) — 1.60 6.67 0.80 1.60 components Amine compound/Sulfur compound (mass ratio) — 1.92 8.00 0.96 1.92 Unsaturated fatty acid polymer/Nonionic surfactant (mass ratio) 4.00 4.00 4.00 4.00 66.67 Amine compound/Nonionic surfactant (mass ratio) 4.80 4.80 4.80 4.80 80.00 Amine compound/Unsaturated fatty acid polymer (mass ratio) 1.20 1.20 1.20 1.20 1.20 Properties Acid value mgKOH/g 38.2 38.2 38.2 38.2 38.2 Base number mgKOH/g 70.7 70.7 70.7 70.7 70.7 Base number/Acid value — 1.8 1.8 1.8 1.8 1.8 Sulfur atom content mass % 0 1.45 0.53 4.38 2.19 Evaluations Processability: average tap torque N .Math. cm 290 265 275 232 238 Self-emulsifiability — A F A F A Hard water stability — A F A F F Compar- Compar- Compar- Compar- Compar- ative ative ative ative ative Example 6 Example 7 Example 8 Example 9 Example 10 Composition Sulfur Sulfurized fat and oil (a-i) mass % 12.5 12.5 12.5 12.5 12.5 compound Sulfurized fat and oil (a-ii) mass % — — — — — Sulfurized fat and oil (a-iii) mass % — — — — — Nonionic POA alkyl ether (b-i), HLB = 12.7 mass % 5.0 5.0 5.0 5.0 surfactant POA alkyl ether (b-ii), HLB = 14.0 mass % — — — — — POA alkyl ether (b-iii), HLB = 3.0 mass % 5.0 — — — Unsaturated Polymerized fatty acid (c-i) mass % 20.0 5.0 35.0 — 20.0 fatty acid Polymerized fatty acid (c-ii) mass % — — — — — polymer Amine Tertiary amine (d-i) mass % 18.5 18.5 18.5 18.5 — compound Tertiary amine (d-ii) mass % 5.5 5.5 5.5 5.5 — Primary amine (d-iii) mass % — — — — 24.0 Carboxylic Tall oil fatty acid mass % 2.0 2.0 2.0 22.0 2.0 acid Neodecanoic acid mass % 4.3 4.3 4.3 4.3 4.3 component Dodecanedioic acid mass % 1.0 1.0 1.0 1.0 1.0 Other Benzotriazole mass % 1.0 1.0 1.0 1.0 1.0 components Methyl oleate mass % 12.0 12.0 12.0 12.0 12.0 Water mass % 18.2 33.2 3.2 18.2 18.2 Total mass % 100.0 100.0 100.0 100.0 100.0 Content Nonionic surfactant/Sulfur compound (mass ratio) 0.40 0.40 0.40 0.40 0.40 ratio of two Unsaturated fatty acid polymer/Sulfur compound (mass ratio) 1.60 0.40 2.80 — 1.60 components Amine compound/Sulfur compound (mass ratio) 1.92 1.92 1.92 1.92 1.92 Unsaturated fatty acid polymer/Nonionic surfactant (mass ratio) 4.00 1.00 7.00 — 4.00 Amine compound/Nonionic surfactant (mass ratio) 4.80 4.80 4.80 4.80 4.80 Amine compound/Unsaturated fatty acid polymer (mass ratio) 1.20 4.80 0.69 — 1.20 Properties Acid value mgKOH/g 38.2 30.4 46.0 68.0 38.2 Base number mgKOH/g 70.7 70.7 70.7 70.7 129.8 Base number/Acid value — 1.8 2.3 1.5 1.0 3.4 Sulfur atom content mass % 2.19 2.19 2.19 2.19 2.19 Evaluations Processability: average tap torque N .Math. cm 236 (*) 230 (*) (*) Self-emulsifiability — A F Hard water stability — F A (*): Since the resulting water-soluble metalworking oil composition had poor emulsification, various evaluations were not performed.

[0257] From Table 1, the metalworking fluid obtained by diluting the water-soluble metalworking oil composition prepared in Example 1 to 10 had a small average tap torque value, and was excellent in processability. The water-soluble metalworking oil composition was also good in self-emulsifiability and hard water stability.

[0258] On the other hand, from Table 2, it is determined that the metalworking fluid obtained by diluting the water-soluble metalworking oil composition prepared in Comparative Example 1 to 3 has a large average tap torque value and is poor in processability. The water-soluble metalworking oil compositions prepared in Comparative Examples 2, 4 to 6, and 8 had a problem in at least one of self-emulsifiability and hard water stability. In Comparative Examples 7, 9, and 10, since the resulting water-soluble metalworking oil composition had poor emulsification, various evaluations were not performed.

Example 11, Comparative Examples 11 to 12

[0259] Sulfur compounds, nonionic surfactants, unsaturated fatty acid polymers, amine compounds, carboxylic acid components, and other components were mixed in the kinds and blending amounts shown in Table 3 to prepare water-soluble metalworking oil compositions, respectively.

[0260] The acid value and the base number of the prepared water-soluble metalworking oil composition were measured, and the turning test was performed. The results are shown in Table 3.

[0261] (4) Turning Test

[0262] The water-soluble metalworking oil compositions obtained in Examples and Comparative Examples were diluted with water to prepare a metalworking fluid having a dilution concentration of 10 mass %. The wear width (unit: μm) of the front flank surface of the tool when the workpiece material was processed under the following conditions was measured using the prepared metalworking fluid. When the value of the wear width was 130 μm or less, it was determined that the metalworking oil was good in processability for a difficult-to-process material. It can be said that as the value of the wear width is smaller, the metalworking oil is more excellent in processability for a difficult-to-process material.

[0263] (Processing Conditions of Workpiece Material) [0264] Lathe: QT-15N (Product name, manufactured by YAMAZAKI MAZAK CORPORATION) [0265] Tool: CNMG120404-MS VP15TF (Product name, manufactured by Mitsubishi Materials Corporation) [0266] Tool tip holder: DCLNL2020K12 (Product name, manufactured by Mitsubishi Materials Corporation) [0267] Workpiece material: SUS630 [0268] Cutting speed: 150 m/min [0269] Feed: 0.2 mm/rev [0270] Cutting: 0.5 mm [0271] Cutting distance: 2,000 m

TABLE-US-00003 TABLE 3 Comparative Comparative Example 11 Example 11 Example 12 Composition Sulfur Sulfurized fat and oil (a-i) mass % 12.5 — — compound Sulfurized fat and oil (a-ii) mass % — — — Sulfurized fat and oil (a-iii) mass % — — — Sulfurized fat and oil (a-iv) mass % — 12.5 5.6 Nonionic POA alkyl ether (b-i), HLB = 12.7 mass % 5.0 5.0 5.0 surfactant POA alkyl ether (b-ii), HLB = 14.0 mass % — — — POA alkyl ether (b-iii), HLB = 3.0 mass % — — — Unsaturated Polymerized fatty acid (c-i) mass % 20.0 20.0 20.0 fatty acid Polymerized fatty acid (c-ii) mass % — — — polymer Amine Tertiary amine (d-i) mass % 18.5 18.5 18.5 compound Tertiary amine (d-ii) mass % 5.5 5.5 5.5 Primary amine (d-iii) mass % — — — Carboxylic tall oil fatty acid mass % 2.0 2.0 2.0 acid Neodecanoic acid mass % 4.3 4.3 4.3 component Dodecanedioic acid mass % 1.0 1.0 1.0 Other Benzotriazole mass % 1.0 1.0 1.0 components Methyl oleate mass % 12.0 12.0 12.0 Water mass % 18.2 18.2 25.1 Total mass % 100.0 100.0 100.0 Content Nonionic surfactant/Sulfur compound (mass ratio) 0.40 0.40 0.89 ratio of 2 Unsaturated fatty acid polymer/Sulfur compound (mass ratio) 1.60 1.60 3.57 components Amine compound/Sulfur compound (mass ratio) 1.92 1.92 4.29 Unsaturated fatty acid polymer/Nonionic surfactant (mass ratio) 4.00 4.00 4.00 Amine compound/Nonionic surfactant (mass ratio) 4.80 4.80 4.80 Amine compound/Unsaturated fatty acid polymer (mass ratio) 1.20 1.20 1.20 Properties Acid value mgKOH/g 38.2 38.2 38.2 Base number mgKOH/g 70.7 70.7 70.7 Base number/Acid value — 1.8 1.8 1.8 Sulfur atom content mass % 2.19 4.88 2.18 Evaluations Turning test: Wear width μm 91 142 138 of front flank surface

[0272] From Table 3, it can be said that the metalworking fluid prepared by diluting the water-soluble metalworking oil composition prepared in Example 11 has a small wear width of the front flank surface of the tool, and therefore has excellent processability even for difficult-to-process materials such as stainless steel.

[0273] On the other hand, in the metalworking fluid prepared by diluting the water-soluble metalworking oil composition prepared in Comparative Examples 11 to 12, the wear width of the front flank surface of the tool was as large as more than 130 μm, resulting in inferior processability for difficult-to-process materials such as stainless steel.