Metalworking fluids

Abstract

To provide a metalworking oil that has excellent lubricity and generates little oil smoke during metalworking.SOLUTION: There are provided a metalworking oil that contains 60 mass% or more and 95 mass% or less of a gas-liquefied oil (GTL) with a flash point of 190°C or higher, and 5 mass% or more and 40 mass% or less of a sulfurized oil or fat as a sulfur-based additive; and a metalworking oil that contains 60 mass% or more and 90 mass% or less of a gas-liquefied oil (GTL) with a flash point of 190°C or higher, and 10 mass% or more and 30 mass% or less of a sulfurized ester as a sulfur-based additive.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a metalworking fluid used in metal processing such as cold forging, press working, and cutting. [Background technology]

[0002] Conventionally, as disclosed in Patent Document 1, metalworking fluids have been used as lubricants in metalworking to prevent seizing due to friction between the tool and the workpiece, deterioration of the workpiece quality, and progression of tool wear. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 6569150 [Overview of the project] [Problems that the invention aims to solve]

[0004] Conventional metalworking fluids have the problem of generating oil fumes due to the heat generated during metalworking, which worsens the working environment.

[0005] The present invention aims to provide a metalworking fluid that exhibits excellent lubricity and generates less oil fumes during metal processing. [Means for solving the problem]

[0006] The metalworking fluid of the present invention is characterized by containing 60% to 95% by mass of GTL with a flash point of 190°C or higher, and containing 5% to 40% by mass of sulfurized oil as a sulfur-based additive.

[0007] This configuration, by including GTL with a flash point of 190°C or higher, can reduce the amount of oil fumes generated during metalworking. Furthermore, by including sulfurized oils as sulfur-based additives, lubricity can be imparted to the metalworking fluid, and the increase in oil fumes generated during metalworking compared to cases without sulfur-based additives can be suppressed. Therefore, it is possible to provide a metalworking fluid with excellent lubricity and low oil fumes generation during metalworking.

[0008] Another metalworking fluid of the present invention is characterized by containing 60% to 90% by mass of GTL with a flash point of 190°C or higher, and containing 10% to 30% by mass of sulfur ester as a sulfur-based additive.

[0009] This configuration, by including GTL with a flash point of 190°C or higher, can reduce the amount of oil fumes generated during metalworking. Furthermore, by including sulfur ester as a sulfur-based additive, lubricity can be imparted to the metalworking fluid, and the increase in oil fumes generated during metalworking compared to cases without sulfur-based additives can be suppressed. Therefore, it is possible to provide a metalworking fluid with excellent lubricity and low oil fumes generation during metalworking.

[0010] In this case, it is preferable to include a metal sulfonate in an amount of 2% by mass or more and 15% by mass or less.

[0011] This configuration allows for a further reduction in the amount of oil fumes generated during metalworking.

[0012] In this case, it is preferable to include zinc dithiophosphate in an amount of 2% by mass or more and 15% by mass or less.

[0013] This configuration can improve the lubricity of metalworking fluids. [Modes for carrying out the invention]

[0014] The metalworking fluid of the present invention comprises GTL and a sulfur-based additive. In addition to GTL and the sulfur-based additive, the metalworking fluid may also contain at least one of a metal sulfonate and zinc dithiophosphate.

[0015] (GTL) Metalworking fluids contain GTL, or gas-to-liquid oil, as a base oil. GTL is synthesized, for example, from natural gas by the Fischer-Tropsch reaction.

[0016] The metalworking fluid includes GTLs with a flash point of 190°C or higher. The higher the flash point of the GTL, the more the amount of oil fumes generated during metalworking can be reduced. The flash point of the GTL is preferably 200°C or higher, and more preferably 230°C or higher. The metalworking fluid may contain one type of GTL or two or more types of GTLs.

[0017] As described later, the GTL content in metalworking fluids is 60% by mass or more and 95% by mass or less when sulfurized oils and fats are included as sulfur-based additives. A GTL content of 60% by mass or more can reduce the amount of oil mist generated during metalworking. A GTL content of 95% by mass or less allows for the addition of the required amount of sulfurized oils and fats. Furthermore, as described later, the GTL content in metalworking fluids is 60% by mass or more and 90% by mass or less when sulfurized esters are included as sulfur-based additives. A GTL content of 60% by mass or more can reduce the amount of oil mist generated during metalworking. A GTL content of 90% by mass or less allows for the addition of the required amount of sulfurized esters.

[0018] The kinematic viscosity of GTL at 4°C is 50 mm 2 It is preferable that the kinematic viscosity of the GTL is 50 mm² or less. 2 Having a viscosity of 0.5 / s or less ensures workability in metal processing. Furthermore, the higher the kinematic viscosity of GTL, the higher its flash point tends to be.

[0019] (Sulfur-based additive) The metalworking fluid contains at least one of sulfonated oils and sulfonated esters as a sulfur-based additive. That is, the metalworking fluid may contain only sulfonated oils, only sulfonated esters, or both sulfonated oils and sulfonated esters among sulfonated oils and sulfonated esters. By including at least one of sulfonated oils and sulfonated esters among the sulfur-based additives, the metalworking fluid can impart lubricity while suppressing an increase in the amount of oil fumes generated during metalworking compared to the case where no sulfur-based additive is included.

[0020] Sulfonated oils are sulfides of oils and fats. Examples of oils and fats include beef tallow, lard, soybean oil, rapeseed oil, coconut oil, and palm oil. The metalworking fluid may contain one type of sulfonated oil or two or more types of sulfonated oils.

[0021] The content of sulfonated oils in the metalworking fluid is 5% by mass or more and 40% by mass or less. By the content of sulfonated oils being 5% by mass or more, appropriate lubricity can be imparted to the metalworking fluid. By the content of sulfonated oils being 40% by mass or less, an increase in the amount of oil fumes generated during metalworking can be avoided.

[0022] Examples of sulfonated esters include methyl sulfonated oleate and methyl sulfonated linoleate. The metalworking fluid may contain one type of sulfonated ester or two or more types of sulfonated esters.

[0023] The content of sulfonated esters in the metalworking fluid is 10% by mass or more and 30% by mass or less. By the content of sulfonated esters being 10% by mass or more, appropriate lubricity can be imparted to the metalworking fluid. By the content of sulfonated esters being less than or equal to 30% by mass, an increase in the amount of oil fumes generated during metalworking can be avoided. The content of sulfonated esters is preferably 10% by mass or more and 20% by mass or less.

[0024] (Metallic sulfonates) Metalworking fluids may contain metal sulfonates. The inclusion of metal sulfonates in metalworking fluids can further reduce the amount of oil mist generated during metalworking. Examples of metal sulfonates include alkali metal sulfonates and alkaline earth metal sulfonates. An example of an alkali metal sulfonate is sodium sulfonate. Examples of alkaline earth metal sulfonates include magnesium sulfonate, calcium sulfonate, and barium sulfonate. Metalworking fluids may contain one type of metal sulfonate, or two or more types of metal sulfonates.

[0025] The metal sulfonate content in metalworking fluids is, for example, 2% by mass or more and 15% by mass or less. A metal sulfonate content of 2% by mass or more effectively reduces the amount of oil mist generated during metalworking. A metal sulfonate content of 15% by mass or less allows for the addition of the required amounts of GTL and sulfur-based additives.

[0026] (Zinc dithiophosphate) Metalworking fluids may contain zinc dithiophosphate. The inclusion of zinc dithiophosphate in metalworking fluids can improve their lubricity. Examples of zinc dithiophosphate include dialkyldithiophosphate and diaryldithiophosphate. Metalworking fluids may contain one type of zinc dithiophosphate or two or more types. The zinc dithiophosphate content in metalworking fluids is, for example, 2% by mass or more and 15% by mass or less.

[0027] (Other ingredients) In addition to GTL and sulfur-based additives, metalworking fluids may contain one or more of the following components: metal sulfonates and zinc dithiophosphate, as well as, for example, higher alcohols, antioxidants, rust inhibitors, and pour point depressants. Furthermore, metalworking fluids may contain one or more of the following: mineral oil, synthetic hydrocarbons, non-ferrous metal corrosion inhibitors, and ester compounds.

[0028] By including higher alcohols in the metalworking fluid, the compatibility between the nonpolar solvent GTL and polar additives such as sulfur-based additives can be improved. Examples of higher alcohols include those with 6 or more carbon atoms. The metalworking fluid may contain one type of higher alcohol, or it may contain two or more types of higher alcohols.

[0029] Examples of antioxidants include phenolic antioxidants and amine-based antioxidants. The metalworking fluid may contain one type of antioxidant or two or more types of antioxidants.

[0030] Examples of rust inhibitors include alkylbenzene sulfonates, alkenyl succinates, benzotriazoles, tolyltriazoles, and thiazole compounds. The metalworking fluid may contain one type of rust inhibitor, or it may contain two or more types of rust inhibitors.

[0031] Examples of pour point depressants include alkylbenzene sulfonates and alkenyl succinate esters, which can be used as polyalkyl methacrylates, polyalkyl acrylates, polyisobutylene, polybutene, alkylnaphthalene condensation products, alkylphenol condensation products, etc. The metalworking fluid may contain one type of pour point depressant, or it may contain two or more types of pour point depressants.

[0032] (Metal processing method) The type of metalworking process in which metalworking fluids are used is not particularly limited, but they can be used, for example, in cold forging, pressing, or cutting. [Examples]

[0033] (Preparation of metalworking fluids) The metalworking fluids for Examples 1-10 and Comparative Examples 1-15 were prepared by adding each material of the metalworking fluid to a container in the proportions shown in Tables 1-3 and stirring. In Tables 1-3, the proportions of each component are shown in mass percent.

[0034] The components shown in Tables 1-3 are as follows: GTL-2…Kinematic viscosity (40℃): 18mm 2 / s, flash point: 230℃ GTL-3…Kinematic viscosity (40℃): 43mm 2 / s, flash point: 265℃ Mineral oil-2…Group I (paraffinic), kinematic viscosity (40℃): 20 mm 2 / s, flash point: 222℃ Mineral oil-3…Group I (paraffinic), kinematic viscosity (40℃): 45 mm 2 / s, flash point: 242℃ Sulfurized oil (derived from vegetable oil)...Sulfur content: 10% by mass Sulfur ester... Sulfur content: 10% by mass Polysulfide...Sulfur content: 39% by mass Calcium sulfonate (containing mineral oil)... Base number: 400 mg KOH / g, Calcium sulfonate content: 50% by mass Zinc dithiophosphate (containing mineral oil): Sulfur content 17.1% by mass, Zinc dithiophosphate content: 75% by mass

[0035] The flash point was measured by the COC method in accordance with JIS K2265. The kinematic viscosity was measured in accordance with JIS K2283.

[0036] (Amount of oil smoke generated) For the metalworking oils of Examples 1 to 10 and Comparative Examples 1 to 15, the weight loss rate was measured as an evaluation index for the amount of oil fume generated. It can be said that the lower the weight loss rate, the less the amount of oil fume generated. The weight loss rate was measured using a differential thermal thermogravimetric simultaneous measurement device (trade name: TG / DTA6300, manufactured by Seiko Instruments Inc.) under an atmosphere of 300 mL / min of nitrogen, heating from 35°C to 550°C at a rate of 20°C / min, and the weight change rate was measured and evaluated as follows. ·When using GTL-2 or mineral oil-2 Evaluation A: The weight loss rate at 220°C is less than 10%, the weight loss rate at 250°C is less than 20%, and the weight loss rate at 300°C is less than 80% Evaluation B: The weight loss rate at 220°C is 10% or more, or the weight loss rate at 250°C is 20% or more, or the weight loss rate at 300°C is 80% or more ·When using GTL-3 or mineral oil-3 Evaluation A: The weight loss rate at 220°C is less than 5%, the weight loss rate at 250°C is less than 10%, and the weight loss rate at 300°C is less than 30% Evaluation B: The weight loss rate at 220°C is 5% or more, or the weight loss rate at 250°C is 10% or more, or the weight loss rate at 300°C is 30% or more The evaluation results are shown in Tables 1 to 3.

[0037] (Lubricity) For the metalworking oils of Examples 1 to 10 and Comparative Examples 1 to 15, the lubricity was measured by the Soda four-ball test and evaluated as follows. Evaluation A: The pressure resistance of the sample is 7 kgf / cm 2 or more Evaluation B: The pressure resistance of the sample is 5 kgf / cm 2 or more and less than 7 kgf / cm 2 Evaluation C: The pressure resistance of the sample is less than 5 kgf / cm 2 The evaluation results are shown in Tables 1 to 3.

[0038]

Table 1

[0039] ​​[Table 2]

[0040] [Table 3]

[0041] As shown in Comparative Examples 7-10, among metalworking fluids using mineral oil as the base oil, Comparative Examples 8-10, which had sulfur-based additives added, showed improved lubricity compared to Comparative Example 7, which did not have sulfur-based additives. On the other hand, Comparative Examples 8-10, which had sulfur-based additives added, showed increased oil mist generation compared to Comparative Example 7, which did not have sulfur-based additives.

[0042] In contrast, as shown in Examples 3-4 and Comparative Examples 11-12, among metalworking fluids using GTL as the base oil, Examples 3-4 and Comparative Example 12, which contained sulfur-based additives, showed improved lubricity compared to Comparative Example 11. Furthermore, in Comparative Example 12, which contained polysulfide as the sulfur-based additive, the amount of oil mist generated increased compared to Comparative Example 11, which did not contain a sulfur-based additive. In contrast, in Examples 3-4, which contained sulfurized oil or sulfurized ester as the sulfur-based additive, the amount of oil mist generated did not increase significantly compared to Comparative Example 11, which did not contain a sulfur-based additive. In particular, in Example 3, which contained sulfurized oil as the sulfur-based additive, the amount of oil mist generated hardly increased compared to Comparative Example 11.

[0043] The above results are for Examples 3-4 and Comparative Examples 7-12, which used GTL-3 or mineral oil-3, which have relatively high flash points, as the base oil. Similar results were obtained for Examples 1-2 and Comparative Examples 1-6, which used GTL-2 or mineral oil-2, which have relatively low flash points, as the base oil.

[0044] From the above, it was found that metalworking fluids containing GTL and at least one of sulfurized oils and sulfurized esters as sulfur-based additives exhibit excellent lubricity and produce less oil mist during metalworking. In other words, it was found that by adding sulfurized oils or sulfurized esters, among the sulfur-based additives, to metalworking fluids using GTL as the base oil, lubricity can be imparted to the metalworking fluid without significantly increasing the amount of oil mist produced during metalworking.

[0045] Furthermore, as shown in Example 6, in the metalworking fluid to which sulfurized oil was added as a sulfur-based additive, even when the content of sulfurized oil was increased to 40% by mass, the amount of oil mist generated hardly increased compared to Example 3, which had a sulfurized oil content of 20% by mass.

[0046] Furthermore, as shown in Example 9, the metalworking fluid with added calcium sulfonate was able to further reduce the amount of oil mist generated compared to Example 3, which did not contain added calcium sulfonate.

Claims

1. It contains 60% to 90% by mass of GTL with a flash point of 190°C or higher. As a sulfur-based additive, it contains sulfurized oils and fats in an amount of 5% to 20% by mass. A metalworking fluid characterized by containing calcium sulfonate in an amount of 2% by mass or more and 15% by mass or less.

2. It contains 60% to 85% by mass of GTL with a flash point of 190°C or higher. As a sulfur-based additive, it contains sulfur esters in an amount of 10% to 30% by mass. A metalworking fluid characterized by containing calcium sulfonate in an amount of 2% by mass or more and 15% by mass or less.

3. The metalworking fluid according to claim 1 or 2, characterized by containing zinc dithiophosphate in an amount of 2% by mass or more and 15% by mass or less.

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