JP7832815B2 - Water-soluble lubricant - Google Patents

Description

The present invention relates to a water-soluble lubricant, an aqueous metalworking fluid obtained by diluting the water-soluble lubricant with water, and a metalworking method comprising the step of processing a workpiece having an aluminum component by applying the aqueous metalworking fluid.

Lubricants are used in a variety of applications, including lubrication of sliding parts in various devices, cooling of heat-generating equipment such as engines, and metalworking applications to improve machinability during metal processing.
In recent years, water-soluble lubricants have become increasingly popular due to safety reasons such as a lower risk of fire.
For example, Patent Document 1 discloses a water-soluble metalworking oil containing at least one compound selected from hydroxy acids, their polycondensates, and dehydration condensates of these with fatty acids, having a predetermined acid value, an amine having an alicyclic or aromatic cyclic group, and a base oil.

Japanese Patent Publication No. 2012-67146

Under these circumstances, there is a need for novel water-soluble lubricants that offer excellent corrosion resistance to various metals and are easily adaptable to a wide range of applications.

The present invention provides a water-soluble lubricant containing a cyclic compound having a ring structure comprising at least one predetermined substructure. Specifically, the present invention provides, for example, the following embodiments [1] to [14].
[1] A water-soluble lubricant containing a cyclic compound (A) having a ring structure (α) that includes at least one substructure represented by the following formula (i) or (ii).
(In the above formula, * indicates the bonding position.)
[2] The water-soluble lubricant according to [1] above, wherein the ring structure (α) comprises at least one selected from an acid anhydride structure and a lactone structure.
[3] The water-soluble lubricant according to [1] or [2] above, wherein the number of ring-forming atoms in the ring structure (α) is 5 to 20.
[4] A water-soluble lubricant according to any one of the above [1] to [3], wherein component (A) comprises one or more selected from a cyclic compound (A1) having a ring structure (α1) represented by the following formula (a-1) and a cyclic compound (A2) having a ring structure (α2) represented by the following formula (a-2).
(At least one hydrogen atom in the above formula may be substituted with a substituent.)
[5] A water-soluble lubricant as described in any one of the above items [1] to [4], which is classified as type A1, type A2, or type A3 as defined in JIS K2241:2017.
[6] A water-soluble lubricant according to any one of the above items [1] to [5], which substantially does not contain a phosphorus-containing compound.
[7] The water-soluble lubricant according to any one of the above items [1] to [6], wherein the content of component (A) is 0.1 to 10.0% by mass on a basis of the total amount of the water-soluble lubricant excluding water.
[8] A water-soluble lubricant according to any one of the above items [1] to [7], further containing water (B).
[9] A water-soluble lubricant as described in any one of the above items [1] to [8], used for metalworking of a workpiece.
[10] The water-soluble lubricant according to [9] above, wherein the workpiece is a workpiece that is subjected to a process using a form-in-place gasket after the metal processing.
[11] The water-soluble lubricant according to [9] or [10] above, wherein the workpiece has a member containing aluminum.
[12] A water-based metalworking fluid comprising a water-soluble lubricant described in any one of the above items [1] to [9], with diluted water.
[13] A metalworking method comprising step (1) of applying the aqueous metalworking fluid described in [12] above to process a workpiece.
[14] The metalworking method according to [13] above, further comprising step (2) of processing using a form-in-place gasket after step (1).

A preferred embodiment of the present invention provides excellent corrosion resistance to various metals (e.g., non-ferrous metals such as aluminum or aluminum alloys) and is easily adaptable to various applications. For example, a more preferred embodiment of the present invention provides excellent corrosion resistance to various metals and can also prepare a water-based metalworking fluid with excellent compatibility with FIPG (liquid gasket).

This is a perspective view showing the composition of a tensile test sample prepared for FIPG conformity testing.

The numerical ranges described herein can be any combination of upper and lower limits. For example, if the numerical range is described as "preferably 30 to 100, more preferably 40 to 80," then the ranges of "30 to 80" and "40 to 100" are also included in the numerical range described herein. Similarly, if the numerical range is described as "preferably 30 or more, more preferably 40 or more, and also preferably 100 or less, more preferably 80 or less," then the ranges of "30 to 80" and "40 to 100" are also included in the numerical range described herein.
In addition, as a numerical range described in this specification, for example, "60 to 100" means a range of "60 or more and 100 or less."

In this specification, "water-soluble lubricant" refers to the undiluted solution before dilution with water to create an aqueous metalworking fluid. This is a suitable form for transportation and storage before use in metalworking, but not intended for direct use in metalworking. Furthermore, "aqueous metalworking fluid" refers to the water-soluble lubricant solution diluted with water, and is a suitable form for use in metalworking.

[Composition of water-soluble lubricants]
A water-soluble lubricant according to one aspect of the present invention contains a cyclic compound (A) having a ring structure (α) that includes at least one substructure represented by the following formula (i) or (ii).
(In the above formula, * indicates the bonding position.)

A water-soluble lubricant according to one aspect of the present invention is a "water-soluble" lubricant.
In this specification, "water-soluble" means that the amount of substance that dissolves in 100 g of water at 25°C is 20 g or more, and that the total light transmittance of the solution at 25°C after adding 20 g of the substance to 100 g of water at 25°C is 90% or more.
In other words, a water-soluble lubricant according to one aspect of the present invention is a lubricant having the above-described characteristics.

A water-soluble lubricant according to one aspect of the present invention may be any of the following: an emulsion type classified as type A1, a soluble type classified as type A2, or a solution type classified as type A3, as defined in JIS K2241:2017.
These water-soluble lubricants, classified as A1, A2, and A3, can be adjusted by appropriately setting the water content, as well as the type and amount of base oil and various additives.
Therefore, the water-soluble lubricant according to one embodiment of the present invention may further contain water (B).
Furthermore, the water-soluble lubricant according to one embodiment of the present invention may further contain a base oil (C).

A water-soluble lubricant according to one embodiment of the present invention preferably contains one or more selected from amine compounds (D) and fatty acids (E), and more preferably contains at least components (D) and (E).
Furthermore, a water-soluble lubricant according to one embodiment of the present invention may contain other components besides components (A) to (E), as long as they do not impair the effects of the present invention.

In one embodiment of the present invention, the total content of components (A) to (C) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, even more preferably 30% by mass or more, and particularly preferably 35% by mass or more, based on the total amount (100% by mass) of the water-soluble lubricant. Furthermore, it may be 40% by mass or more, 45% by mass or more, 50% by mass or more, 55% by mass or more, or 60% by mass or more. It may also be 100% by mass or less, 95% by mass or less, 90% by mass or less, 85% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, 65% by mass or less, or 60% by mass or less.

In one embodiment of the present invention, the total content of components (A) to (E) is preferably 20% by mass or more, more preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more, based on the total amount (100% by mass) of the water-soluble lubricant. It may also be 75% by mass or more, 80% by mass or more, 85% by mass or more, or 90% by mass or more, or 100% by mass or less, 99.9% by mass or less, 99.5% by mass or less, or 99.0% by mass or less.
The following describes the components contained in a water-soluble lubricant according to one embodiment of the present invention.

<Component (A): Cyclic compound>
A water-soluble lubricant according to one aspect of the present invention contains a cyclic compound (A) having a ring structure (α) that includes at least one substructure represented by the following formula (i) or (ii).
(In the above formula, * indicates the bonding position.)

One embodiment of the present invention provides a water-soluble lubricant containing a cyclic compound (A) having a ring structure (α) comprising at least one substructure represented by formula (i) or (ii) above. This allows for the preparation of an aqueous metalworking fluid that improves the corrosion resistance of various metals (particularly non-ferrous metals such as aluminum or aluminum alloys) while also exhibiting excellent compatibility with FIPG. The excellent compatibility of the aqueous metalworking fluid with FIPG helps avoid adverse effects during post-processing of the workpiece. On the other hand, compounds without the ring structure (α) do not adequately improve the corrosion resistance of various metals.

The substructure represented by formula (i) or (ii) above may be a structure formed by intramolecular dehydration condensation of a chain-like compound.
For example, in a polycarboxylic acid having two or more carboxyl groups (-COOH) in the molecule, the two carboxyl groups in the molecule undergo dehydration condensation to form a cyclic compound having a ring structure (α) that includes both the substructures represented by formulas (i) and (ii) above. This cyclic compound is also included in the cyclic compound (A) used in one aspect of the present invention.

In one aspect of the present invention, the cyclic compound (A) used in the ring structure (α) preferably contains at least one selected from an acid anhydride structure and a lactone structure, from the viewpoint of providing a water-soluble lubricant capable of preparing an aqueous metalworking fluid with improved corrosion resistance and compatibility with FIPG for various metals. In particular, it is more preferable that the structure contains a lactone structure, from the viewpoint of providing a water-soluble lubricant capable of preparing an aqueous metalworking fluid with improved compatibility with FIPG.

From the viewpoint of providing a water-soluble lubricant that can prepare an aqueous metalworking fluid with improved corrosion resistance and compatibility with FIPG for various metals, the number of ring-forming atoms in the ring structure (α) is preferably 5 to 20, more preferably 5 to 16, more preferably 5 to 12, even more preferably 5 to 10, even more preferably 5 to 8, and particularly preferably 5 or 6.
In this specification, the "number of ring-forming atoms" of a ring structure (α) refers to the number of atoms that constitute the ring structure (α) itself, and does not include atoms that do not constitute a ring (for example, hydrogen atoms bonded to atoms that constitute a ring) or atoms included in substituents when the ring is substituted by substituents.

In one aspect of the present invention, component (A) used is preferably a water-soluble lubricant that can prepare an aqueous metalworking fluid with improved corrosion resistance and compatibility with FIPG for various metals, and preferably contains one or more cyclic compounds (A1) having a ring structure (α1) represented by the following formula (a-1) and a cyclic compound (A2) having a ring structure (α2) represented by the following formula (a-2). In particular, it is more preferable to include a cyclic compound (A1) from the viewpoint of preparing an aqueous metalworking fluid with improved compatibility with FIPG.

At least one hydrogen atom in the above formula may be substituted with a substituent.
Examples of such substituents include hydroxyl groups, C1-C30 alkyl groups, C1-C30 alkyl groups having hydroxyl groups, C1-C30 alkenyl groups, cycloalkyl groups, and aryl groups.

Examples of the alkyl groups include methyl group, ethyl group, propyl group (n-propyl group, i-propyl group), butyl group (n-butyl group, i-butyl group, s-butyl group, t-butyl group), pentyl group (n-pentyl group, i-pentyl group, neopentyl group), hexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, and the like.
The alkyl group may be a linear alkyl group or a branched alkyl group.
The number of carbon atoms in the alkyl group is 1 to 30, but may be 1 to 24, 1 to 20, or 1 to 16.

Examples of alkyl groups having a hydroxyl group include groups in which at least one hydrogen atom of the above-mentioned linear alkyl group or branched alkyl group is substituted with a hydroxyl group.

Examples of the aforementioned alkenyl group include ethenyl group (vinyl group), propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, octadecenyl group, and the like.
The alkenyl group may be a linear alkenyl group or a branched alkenyl group.
The number of carbon atoms in the alkenyl group is 1 to 30, but may be 1 to 24, 1 to 20, or 1 to 16.

Examples of the cycloalkyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and adamantyl groups. The number of ring-forming carbon atoms in the cycloalkyl group may be 3 to 20, 5 to 12, or 5 to 6.
Examples of the aryl group include a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, anthracenyl group, a phenanthryl group, and a fluorene group. The number of ring-forming carbon atoms in the aryl group may be 6 to 18, 6 to 15, or 6 to 12.
Furthermore, at least one hydrogen atom of the above-mentioned cycloalkyl group and aryl group may be substituted with a group selected from a hydroxyl group, a C1-C10 alkyl group, and a C1-C10 alkenyl group.

Among these, in one embodiment of the present invention, the substituents of the ring structures (α1) and (α2) may be groups selected from a hydroxyl group, a C1-C30 alkyl group, and a C1-C30 alkyl group having a hydroxyl group; or groups selected from a hydroxyl group, a C1-C16 alkyl group, and a C1-C10 alkyl group having a hydroxyl group; or groups selected from a hydroxyl group, a C1-C16 alkyl group, and a methylol group ( _-CH2OH ).

In the ring structures (α1) and (α2), the positions and number of substituents can be adjusted as appropriate.
For example, a cyclic compound (A1) used in one aspect of the present invention is a compound represented by the following general formula (a-11).
Furthermore, a cyclic compound (A2) used in one aspect of the present invention is a compound represented by the following general formula (a-21).
In the general formulas (a-11) and (a-21), R ^A is independently a substituent, and the form of the substituent is the same as the substituents on the ring structures (α1) and (α2).

In one embodiment of the present invention, the total content ratio of components (A1) and (A2) is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass, based on the total amount (100% by mass) of component (A) contained in the water-soluble lubricant.

In one embodiment of the present invention, from the viewpoint of providing a water-soluble lubricant capable of preparing an aqueous metalworking fluid with improved corrosion resistance and compatibility with FIPG for various metals, the content of component (A) is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, even more preferably 0.4% by mass or more, particularly preferably 0.5% by mass or more, based on the total amount of the water-soluble lubricant excluding water (100% by mass), and may also be 0.6% by mass or more, 0.8% by mass or more, or 1.0% by mass or more, or 10.0% by mass or less, 9.5% by mass or less, 9.0% by mass or less, 8.5% by mass or less, 8.0% by mass or less, 7.5% by mass or less, 7.0% by mass or less, or 6.5% by mass or less.
Furthermore, even when using aqueous lubricants classified as emulsion type A1, soluble type A2, and solution type A3 as defined in JIS K2241:2017, the content of component (A) is within the range described above, but at least one of the lower limit and upper limit may be within the range shown below.

When using an emulsion-type water-soluble lubricant classified as type A1 as defined in JIS K2241:2017, the content of component (A) may be 6.0% by mass or less, 5.5% by mass or less, 5.0% by mass or less, 4.5% by mass or less, 4.0% by mass or less, 3.5% by mass or less, 3.0% by mass or less, or 2.5% by mass or less, based on the total amount of the water-soluble lubricant excluding water (100% by mass).

When using a soluble water-soluble lubricant classified as type A2 according to JIS K2241:2017, the content of component (B) may be 1.2% by mass or more, 1.5% by mass or more, or 1.6% by mass or more, based on the total amount of the water-soluble lubricant excluding water (100% by mass), or it may be 6.0% by mass or less, 5.5% by mass or less, 5.0% by mass or less, 4.5% by mass or less, or 4.0% by mass or less.

When using a solution-type water-soluble lubricant classified as type A3 as defined in JIS K2241:2017, the content of component (A) may be 1.2% by mass or more, 1.5% by mass or more, 1.6% by mass or more, 1.7% by mass or more, 2.0% by mass or more, 2.2% by mass or more, 2.5% by mass or more, 2.7% by mass or more, 3.0% by mass or more, 3.2% by mass or more, 3.5% by mass or more, 3.7% by mass or more, 4.0% by mass or more, 4.2% by mass or more, or 4.5% by mass or more, based on the total amount (100% by mass) of the water-soluble lubricant excluding water.

In one embodiment of the present invention, from the viewpoint of providing a water-soluble lubricant capable of preparing an aqueous metalworking fluid with improved corrosion resistance and compatibility with FIPG for various metals, the content of component (A) is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, even more preferably 0.7% by mass or more, and particularly preferably 1.0% by mass or more, based on the total amount (100% by mass) of the water-soluble lubricant. Alternatively, it may be 10.0% by mass or less, 9.0% by mass or less, 8.0% by mass or less, 7.0% by mass or less, 6.0% by mass or less, 5.0% by mass or less, 4.5% by mass or less, or 4.0% by mass or less.

<Component (B): Water>
A water-soluble lubricant according to one embodiment of the present invention may further contain water (B). By making the water-soluble lubricant water-soluble, flame retardancy can be imparted, making it a non-hazardous material and improving handling during storage. Furthermore, by adjusting the water (B) content, it is possible to make a lubricant that is classified as one of the desired types A1, A2, and A3 as defined in JIS K2241:2017.
The water component (B) used in one aspect of the present invention is not particularly limited and may be any of the following: distilled water, deionized water, tap water, industrial water, etc.

In one embodiment of the present invention, the content of component (B) is preferably 0.1 parts by mass or more, more preferably 1.0 part by mass or more, even more preferably 2.0 parts by mass or more, even more preferably 3.0 parts by mass or more, particularly preferably 4.0 parts by mass or more, based on 100 parts by mass of the total amount of components other than water in the water-soluble lubricant. It may also be 4.5 parts by mass or more, 5.0 parts by mass or more, 5.5 parts by mass or more, 6.0 parts by mass or more, 6.5 parts by mass or more, or 7.0 parts by mass or more. Alternatively, it may be 500 parts by mass or less, more preferably 470 parts by mass or less, even more preferably 450 parts by mass or less, even more preferably 420 parts by mass or less, particularly preferably 400 parts by mass or less. Furthermore, it may be 350 parts by mass or less, 320 parts by mass or less, or 300 parts by mass or less.
Furthermore, even when using aqueous lubricants classified as emulsion type A1, soluble type A2, and solution type A3 as defined in JIS K2241:2017, the content of component (B) is within the range described above, but at least one of the lower limit and upper limit may be within the range shown below.

When using an emulsion-type water-soluble lubricant classified as type A1 as defined in JIS K2241:2017, the content of component (B) may be 300 parts by mass or less, 200 parts by mass or less, 100 parts by mass or less, 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, 55 parts by mass or less, 50 parts by mass or less, 45 parts by mass or less, 40 parts by mass or less, 35 parts by mass or less, 30 parts by mass or less, 25 parts by mass or less, 20 parts by mass or less, 15 parts by mass or less, or 10 parts by mass or less, relative to 100 parts by mass of the total amount of components other than water in the water-soluble lubricant.

When using a soluble water-soluble lubricant classified as type A2 according to JIS K2241:2017, the content of component (B) may be 10 parts by mass or more, 30 parts by mass or more, or 50 parts by mass or more, based on 100 parts by mass of the total amount of components other than water in the water-soluble lubricant. Alternatively, it may be 300 parts by mass or less, 200 parts by mass or less, 100 parts by mass or less, 80 parts by mass or less, or 70 parts by mass or less.

When using a solution-type water-soluble lubricant classified as type A3 as defined in JIS K2241:2017, the content of component (B) may be 10 parts by mass or more, 30 parts by mass or more, 50 parts by mass or more, 70 parts by mass or more, 100 parts by mass or more, 120 parts by mass or more, 130 parts by mass or more, 140 parts by mass or more, 150 parts by mass or more, 160 parts by mass or more, 170 parts by mass or more, 180 parts by mass or more, 190 parts by mass or more, or 200 parts by mass or more, relative to 100 parts by mass of the total amount of components other than water in the water-soluble lubricant.

In one embodiment of the present invention, the content of component (B) is preferably 1 to 99% by mass, more preferably 2 to 90% by mass, even more preferably 3 to 85% by mass, even more preferably 4 to 80% by mass, and particularly preferably 5 to 75% by mass, based on the total amount (100% by mass) of the water-soluble lubricant.

<Component (C): Base oil>
A water-soluble lubricant according to one embodiment of the present invention may further contain a base oil (C). By using a water-soluble lubricant containing a base oil, when used as a water-based metalworking fluid, it is possible to obtain a water-based metalworking fluid with superior metalworkability. Furthermore, by adjusting the content of the base oil (C), it is possible to obtain a lubricant that is classified as one of the desired types A1, A2, and A3 as defined in JIS K2241:2017.
In one aspect of the present invention, the base oil (C) used may be one or more selected from mineral oil and synthetic oil.

Examples of mineral oils include atmospheric residues obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate-based crude oil, and naphthenic crude oil; distillates obtained by vacuum distillation of these atmospheric residues; and refined oils obtained by subjecting the distillates to one or more refining processes such as solvent dewaxing, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

Examples of synthetic oils include poly-α-olefins such as α-olefin homopolymers or α-olefin copolymers (e.g., 8-14 carbon-14 α-olefin copolymers such as ethylene-α-olefin copolymers); isoparaffins; polyalkylene glycols; ester oils such as polyol esters and dibasic acid esters; ether oils such as polyphenyl ethers; alkylbenzenes; alkylnaphthalenes; and synthetic oils (GTL) obtained by isomerizing waxes produced from natural gas by the Fischer-Tropsch process, etc. (GTL waxes (Gas To Liquids Wax)).

The kinematic viscosity of the base oil (C) used in one aspect of the present invention at 40°C is preferably 2.0 to 150 ^mm² /s, more preferably 3.0 to 120 ^mm² /s, even more preferably 5.0 to 100 ^mm² /s, even more preferably 6.0 to 80 ^mm² /s, and particularly preferably 7.0 to 60 ^mm² /s, from the viewpoint of providing a water-soluble lubricant that can be used as a water-based metalworking fluid with excellent workability.

In a water-soluble lubricant according to one aspect of the present invention, the content of component (C) may be 0% by mass or more, 0.1% by mass or more, 1.0% by mass or more, 5.0% by mass or more, 7.0% by mass or more, or 10% by mass or more, based on the total amount of the water-soluble lubricant excluding water (100% by mass), or it may be 99% by mass or less, 98% by mass or less, 95% by mass or less, 90% by mass or less, 85% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, 65% by mass or less, or 60% by mass or less.
Furthermore, even when using aqueous lubricants classified as A1 type emulsion, A2 type soluble, or A3 type solution as defined in JIS K2241:2017, the content of component (C) is within the range described above, but at least one of the lower and upper limits may be within the range shown below.

When using an emulsion-type water-soluble lubricant classified as type A1 as defined in JIS K2241:2017, the content of component (C) may be 15% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, 35% by mass or more, or 40% by mass or more, based on the total amount (100% by mass) of the water-soluble lubricant excluding water.

When using a soluble water-soluble lubricant classified as type A2 as specified in JIS K2241:2017, the content of component (C) may be 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, or 12% by mass or less, based on the total amount of the water-soluble lubricant excluding water (100% by mass).

When a water-soluble solution-type lubricant classified as type A3 as defined in JIS K2241:2017 is used, the content of component (C) may be 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, 5.0% by mass or less, 2.0% by mass or less, 1.0% by mass or less, 0.1% by mass or less, or 0.01% by mass or less, based on the total amount of the water-soluble lubricant excluding water (100% by mass).
Furthermore, if the solution is classified as type A3 and is a water-soluble lubricant, it is not necessary to include component (C).

In one embodiment of the present invention, the content of component (C) may be 0% by mass or more, 0.1% by mass or more, 1.0% by mass or more, 5.0% by mass or more, 7.0% by mass or more, or 10.0% by mass or more, based on the total amount (100% by mass) of the water-soluble lubricant, or it may be 95% by mass or less, 90% by mass or less, 85% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, or 55% by mass or less.

<Component (D): Amine compound>
A water-soluble lubricant according to one embodiment of the present invention preferably further contains an amine compound (D). When a water-soluble lubricant containing component (D) is mixed with diluting water to form an aqueous metalworking fluid, it can achieve a good emulsification state and become an aqueous metalworking fluid with improved antibacterial properties, rust prevention properties, and workability.
Furthermore, component (D) may be used alone or in combination of two or more components.

From the same viewpoint as described above, in a water-soluble lubricant according to one embodiment of the present invention, the content of component (D) is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, even more preferably 5.0% by mass or more, even more preferably 7.0% by mass or more, particularly preferably 9.0% by mass or more, based on the total amount of the water-soluble lubricant excluding water (100% by mass), and may also be 10% by mass or more, 12% by mass or more, or 15% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 87% by mass or less, even more preferably 85% by mass or less, particularly preferably 82% by mass or less.
Furthermore, even when using aqueous lubricants classified as emulsion type A1, soluble type A2, and solution type A3 as defined in JIS K2241:2017, the content of component (D) is within the range described above, but at least one of the lower and upper limits may be within the range shown below.

When using an emulsion-type water-soluble lubricant classified as type A1 as specified in JIS K2241:2017, the content of component (D) may be 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, 25% by mass or less, or 20% by mass or less, based on the total amount of the water-soluble lubricant excluding water (100% by mass).

When using a soluble water-soluble lubricant classified as type A2 according to JIS K2241:2017, the content of component (D) may be 20% or more by mass, 30% or more by mass, or 40% or more by mass, based on the total amount of the water-soluble lubricant excluding water (100% by mass), or it may be 80% or less by mass, 70% or less by mass, or 60% or less by mass.

When using a solution-type water-soluble lubricant classified as Type A3 as defined in JIS K2241:2017, the content of component (D) may be 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, or 70% by mass or more, based on the total amount (100% by mass) of the water-soluble lubricant excluding water.

Furthermore, from the same viewpoint as described above, in one embodiment of the present invention, the content of component (D) is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 5.0% by mass or more, even more preferably 7.0% by mass or more, particularly preferably 10% by mass or more, based on the total amount (100% by mass) of the water-soluble lubricant, and also preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, even more preferably 35% by mass or less, particularly preferably 30% by mass or less.

Component (D) used in one aspect of the present invention may be any of the following: a monoamine having one amino nitrogen atom in one molecule, a diamine having two amino nitrogen atoms in one molecule, or a polyamine having three or more amino nitrogen atoms in one molecule.
Polyamines also include cyclic compounds having a triazine skeleton, such as hexahydro-1,3,5-tris-(2-hydroxyethyl)triazine.

Among these, from the viewpoint of creating a water-soluble lubricant that can become a water-based metalworking fluid with improved antibacterial properties, rust prevention, and workability, it is preferable that component (D) used in one embodiment of the present invention contains a monoamine.

In one aspect of the present invention, the monoamine used as component (D) is classified into primary amines represented by the following formula (i), secondary amines represented by the following formula (ii), and tertiary amines represented by the following formula (iii), depending on the number of substituents R.

In the above formula, each R independently represents a substituent. Multiple Rs may be the same or different from one another. Examples of substituents include alkyl groups, alkyl groups having a hydroxyl group, alkenyl groups, cycloalkyl groups, phenyl groups, and benzyl groups.

Examples of alkyl groups that can be selected as substituent R include methyl group, ethyl group, propyl group (n-propyl group, i-propyl group), butyl group (n-butyl group, i-butyl group, s-butyl group, t-butyl group), pentyl group (n-pentyl group, i-pentyl group, neopentyl group), hexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, and the like.
The alkyl group may be a linear alkyl group or a branched alkyl group.
Furthermore, from the same viewpoint as above, the number of carbon atoms in the alkyl group is preferably 1 to 30, more preferably 1 to 20, even more preferably 1 to 10, even more preferably 1 to 6, and particularly preferably 1 to 4.

Examples of alkyl groups having a hydroxyl group that can be selected as substituent R include groups in which at least one hydrogen atom of the above-mentioned alkyl group is substituted with a hydroxyl group.
The alkyl group constituting the group may be a linear alkyl group or a branched alkyl group.
From the same viewpoint as above, the number of carbon atoms in the alkyl group having a hydroxyl group is preferably 1 to 30, more preferably 1 to 20, even more preferably 1 to 10, even more preferably 1 to 6, and particularly preferably 2 to 4.

Examples of alkenyl groups that can be selected as substituent R include ethenyl group (vinyl group), propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, octadecenyl group, and the like.
The alkenyl group may be a linear alkenyl group or a branched alkenyl group.
Furthermore, from the same viewpoint as above, the number of carbon atoms in the alkenyl group is preferably 1 to 30, more preferably 1 to 20, even more preferably 1 to 10, even more preferably 1 to 6, and particularly preferably 1 to 3.

Examples of cycloalkyl groups that can be selected as substituent R include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and adamantyl groups.

From the same viewpoint as above, component (D) used in one aspect of the present invention preferably contains an alkanolamine having at least one alkyl group having a hydroxyl group.
Examples of alkanolamines include primary alkanolamines in which R in formula (i) is an alkyl group having a hydroxyl group, secondary alkanolamines in which at least one of R in formula (ii) is an alkyl group having a hydroxyl group, and tertiary alkanolamines in which at least one of R in formula (iii) is an alkyl group having a hydroxyl group.

Examples of primary alkanolamines include ethanolamine, n-propanolamine, isopropanolamine, n-butanolamine, isobutanolamine (2-amino-2-methyl-1-propanol), and t-butanolamine.

Examples of secondary alkanolamines include monoethanolamines such as N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, N-octylethanolamine, N-stearylethanolamine, N-oleylethanolamine, N-cyclohexylethanolamine, N-phenylethanolamine, and N-benzylethanolamine; monopropanolamines such as N-methylpropanolamine, N-ethylpropanolamine, N-propylpropanolamine, N-butylpropanolamine, N-octylpropanolamine, N-stearylpropanolamine, N-oleylpropanolamine, N-cyclohexylpropanolamine, N-phenylpropanolamine, and N-benzylpropanolamine; and diethanolamines and dipropanolamines.

Examples of tertiary alkanolamines include monoethanolamines such as N-dimethylethanolamine, N-diethylethanolamine, N-dipropylethanolamine, N-dibutylethanolamine, N-dioctylethanolamine, N-distearylethanolamine, N-dioleylethanolamine, N-dicyclohexylethanolamine, N-diphenylethanolamine, and N-dibenzylethanolamine; monopropanolamines such as N-dimethylpropanolamine, N-diethylpropanolamine, N-dipropylpropanolamine, N-dibutylpropanolamine, N-dioctylpropanolamine, N-distearylpropanolamine, N-dioleylpropanolamine, N-dicyclohexylpropanolamine, N-diphenylpropanolamine, and N-dibenzylpropanolamine; and N-dimethylpropanolamine. Examples include diethanolamines such as N-ethyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine, N-butyldiethanolamine, N-octyldiethanolamine, N-stearyldiethanolamine, N-oleyldiethanolamine, N-cyclohexyldiethanolamine, N-phenyldiethanolamine, and N-benzyldiethanolamine; dipropanolamines such as N-methyldipropanolamine, N-ethyldipropanolamine, N-propyldipropanolamine, N-butyldipropanolamine, N-octyldipropanolamine, N-stearyldipropanolamine, N-oleyldipropanolamine, N-cyclohexyldipropanolamine, N-phenyldipropanolamine, and N-benzyldipropanolamine; and triethanolamine and tripolamine.

The alkanolamine content may be 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 35% by mass or more, or 40% by mass or more, based on the total amount (100% by mass) of component (D) contained in the water-soluble lubricant. Alternatively, it may be 100% by mass or less, 95% by mass or less, 90% by mass or less, 85% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, or 65% by mass or less.

In one aspect of the present invention, component (D) is preferably an alicyclic amine, from the same viewpoint as described above.
Examples of alicyclic amines include primary alicyclic amines in which R in formula (i) is a cycloalkyl group, secondary alicyclic amines in which at least one of R in formula (ii) is a cycloalkyl group, and tertiary alicyclic amines in which at least one of R in formula (iii) is a cycloalkyl group.

Examples of primary alicyclic amines include N-cyclohexylamines.
Examples of secondary alicyclic amines include monocyclohexylamines such as N-methylcyclohexylamine, N-ethylcyclohexylamine, N-propylcyclohexylamine, and N-oleylcyclohexylamine; monocyclohexyl alkanolamines such as N-cyclohexylethanolamine and N-cyclohexylpropanolamine; and N-dicyclohexylamine.
Examples of tertiary alicyclic amines include dialkylmonocyclohexylamines such as N-dimethylcyclohexylamine, N-diethylcyclohexylamine, N-dipropylcyclohexylamine, N-dioleylcyclohexylamine, and N-dicyclohexylamine; monocyclohexyldialkanolamines such as N-cyclohexyldiethanolamine and N-cyclohexyldipropanolamine; monoalkyldicyclohexylamines such as N-methyldicyclohexylamine, N-ethyldicyclohexylamine, N-propyldicyclohexylamine, and N-oleyldicyclohexylamine; dicyclohexylalkanolamines such as N-dicyclohexylethanolamine and N-dicyclohexylpropanolamine; and tricyclohexylamines.

The content of alicyclic amines may be 10% or more, 20% or more, 25% or more, 30% or more, or 35% or more, based on the total amount (100% by mass) of component (D) contained in the water-soluble lubricant. Alternatively, it may be 100% or less, 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, or 65% or less by mass.

<Component (E): Fatty acids>
A water-soluble lubricant according to one embodiment of the present invention preferably further contains fatty acids (E).
By including component (E), it is possible to create a water-soluble lubricant that can be used as a water-based metalworking fluid with improved emulsification stability, rust prevention, and workability.
In one embodiment of the present invention, component (E) may be used alone or in combination of two or more components.

From the same viewpoint as described above, in a water-soluble lubricant according to one embodiment of the present invention, the content of component (E) is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 5.0% by mass or more, even more preferably 7.0% by mass or more, particularly preferably 10% by mass or more, based on the total amount of the water-soluble lubricant excluding water (100% by mass), and also preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, even more preferably 40% by mass or less, particularly preferably 30% by mass or less.
Furthermore, even when using aqueous lubricants classified as emulsion type A1, soluble type A2, and solution type A3 as defined in JIS K2241:2017, the content of component (E) is within the range described above, but at least one of the lower and upper limits may be within the range shown below.

When using an emulsion-type water-soluble lubricant classified as type A1 as specified in JIS K2241:2017, the content of component (E) may be 12% by mass or more, 15% by mass or more, 17% by mass or more, 20% by mass or more, or 22% by mass or more, based on the total amount of the water-soluble lubricant excluding water (100% by mass).

When using a soluble water-soluble lubricant classified as type A2 according to JIS K2241:2017, the content of component (E) may be 12% by mass or more, or 15% by mass or more, based on the total amount of the water-soluble lubricant excluding water (100% by mass), or it may be 25% by mass or less, 22% by mass or less, or 20% by mass or less.

When using a solution-type water-soluble lubricant classified as type A3 as defined in JIS K2241:2017, the content of component (E) may be 25% by mass or less, 22% by mass or less, 20% by mass or less, 17% by mass or less, or 15% by mass or less, based on the total amount of the water-soluble lubricant excluding water (100% by mass).

Furthermore, from the same viewpoint as described above, in one embodiment of the present invention, the content of component (E) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, even more preferably 1.5% by mass or more, particularly preferably 2.0% by mass or more, based on the total amount (100% by mass) of the water-soluble lubricant, and also preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, even more preferably 35% by mass or less, particularly preferably 30% by mass or less.

In one embodiment of the present invention, from the viewpoint of providing a water-soluble lubricant that can be used as a water-based metalworking fluid with good stock stability and improved machinability, the content ratio of component (D) to component (E) [(D)/(E)] is preferably 0.01 to 10.0, more preferably 0.05 to 9.0, even more preferably 0.1 to 8.5, even more preferably 0.2 to 8.0, even more preferably 0.3 to 7.5, and particularly preferably 0.5 to 7.0 by mass ratio.

Examples of component (E) used in one aspect of the present invention include fatty acids, hydroxy fatty acids, aliphatic dicarboxylic acids, dimer acids of fatty acids, and polymerized fatty acids of hydroxyunsaturated fatty acids.

Examples of the aforementioned fatty acids include saturated aliphatic monocarboxylic acids such as octanoic acid, 2-ethylhexanoic acid, trimethylhexanoic acid, decanoic acid, neodecanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, pentadecanoic acid, heptadecanoic acid, nonadecanoic acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and isostearic acid, as well as unsaturated aliphatic monocarboxylic acids such as octenic acid, nonenic acid, decenoic acid, undecenoic acid, oleic acid, elaidic acid, erucic acid, nervonic acid, linoleic acid, γ-linolenic acid, arachidonic acid, α-linolenic acid, stearidonic acid, eicosapentaenoic acid, and docosahexaenoic acid.
Alternatively, a mixture of unsaturated fatty acids such as tall oil fatty acids, soybean oil fatty acids, palm oil fatty acids, flaxseed oil fatty acids, rice bran oil fatty acids, and cottonseed oil fatty acids may be used.
The number of carbon atoms in the fatty acid is preferably 8 to 30, more preferably 10 to 25, and even more preferably 10 to 20.

Examples of the aforementioned hydroxy fatty acids include hydroxylauric acid, hydroxymyristic acid, hydroxypalmitic acid, hydroxystearic acid, hydroxyarachinic acid, hydroxybehenic acid, and hydroxyoctadecenoic acid.
The number of carbon atoms in the hydroxy fatty acid is preferably 8 to 30, more preferably 10 to 25, and even more preferably 10 to 20.

Examples of the aliphatic dicarboxylic acid include sebacic acid, dodecanediic acid, dodecylsuccinic acid, laurylsuccinic acid, stearylsuccinic acid, and isostearylsuccinic acid.
The aliphatic dicarboxylic acid preferably has 8 to 30 carbon atoms, more preferably 10 to 25 carbon atoms, and even more preferably 10 to 20 carbon atoms.

Examples of hydroxyunsaturated fatty acids that constitute the polymerized fatty acids of the aforementioned hydroxyunsaturated fatty acids include ricinoleic acid (12-hydroxyoctadeca-9-enonic acid). Alternatively, a fatty acid mixture containing ricinoleic acid, such as castor oil, may be used.
Examples of polymerized fatty acids of hydroxyunsaturated fatty acids include condensed fatty acids, which are dehydrated polycondensates of hydroxyunsaturated fatty acids, and condensed fatty acids obtained by dehydrated condensation of the alcoholic hydroxyl group of a condensed fatty acid (a dehydrated polycondensate of hydroxyunsaturated fatty acid) with a monocarboxylic acid.

The acid value of component (E) is usually 0 mg KOH/g or higher, preferably 5 to 120 mg KOH/g, more preferably 10 to 100 mg KOH/g, and even more preferably 15 to 90 mg KOH/g, from the viewpoint of providing a water-soluble lubricant that can be used as a water-based metalworking fluid with improved workability.
Furthermore, even when using aqueous lubricants classified as A1 type emulsion, A2 type soluble, or A3 type solution as defined in JIS K2241:2017, the acid value of component (E) is within the range described above, but at least one of the lower and upper limits may be within the range shown below.
When using an emulsion-type water-soluble lubricant classified as type A1 as specified in JIS K2241:2017, the acid value of component (E) may be 20 mg KOH/g or more, 30 mg KOH/g or more, 40 mg KOH/g or more, or 50 mg KOH/g or more.
When using a soluble water-soluble lubricant classified as type A2 as specified in JIS K2241:2017, the acid value of component (E) may be 20 mg KOH/g or more, or 30 mg KOH/g or more, or 70 mg KOH/g or less, or 50 mg KOH/g or less.
When using a solution-type water-soluble lubricant classified as type A3 as specified in JIS K2241:2017, the acid value of component (E) may be 70 mg KOH/g or less, 50 mg KOH/g or less, 40 mg KOH/g or less, or 30 mg KOH/g or less.

The hydroxyl value of component (E) is preferably 0 to 80 mg KOH/g, more preferably 0 to 60 mg KOH/g, and even more preferably 0 to 40 mg KOH/g.
From the above viewpoint, the ratio of the acid value to the hydroxyl value of component (E) [acid value/hydroxyl value] is preferably 1.5 to 50, more preferably 2.0 to 40, and even more preferably 2.5 to 30.
In this specification, the acid value refers to the value measured in accordance with JIS K2501:2003 (indicator photometric titration method), and the hydroxyl value refers to the value measured in accordance with JIS K0070:1992.

<Nonionic surfactants>
A water-soluble lubricant according to one embodiment of the present invention may further contain a nonionic surfactant. By including a nonionic surfactant, the water-soluble lubricant can be made into a water-based metalworking fluid with improved emulsification stability and workability.
In one embodiment of the present invention, the water-soluble lubricant may be used alone or in combination of two or more nonionic surfactants.

From the above viewpoint, in one embodiment of the present invention, the content of the nonionic surfactant is preferably 0.5 to 30.0% by mass, more preferably 1.0 to 30.0% by mass, even more preferably 1.5 to 20.0% by mass, even more preferably 2.0 to 15.0% by mass, and particularly preferably 2.5 to 10.0% by mass, based on the total amount of the water-soluble lubricant excluding water (100% by mass).

From the above viewpoint, in one embodiment of the present invention, the content of the nonionic surfactant is preferably 0.1 to 15.0% by mass, more preferably 0.5 to 12.0% by mass, even more preferably 1.0 to 10.0% by mass, even more preferably 1.5 to 8.0% by mass, and particularly preferably 2.0 to 6.0% by mass, based on the total amount (100% by mass) of the water-soluble lubricant.

In one aspect of the present invention, the HLB of the nonionic surfactant used is preferably 6.0 or higher, more preferably 7.0 or higher, even more preferably 8.0 or higher, even more preferably 9.0 or higher, particularly preferably 10.0 or higher, and also 18.0 or lower, preferably 17.0 or lower, more preferably 16.0 or lower, even more preferably 15.0 or lower, and even more preferably 14.5 or lower, from the viewpoint of providing a water-soluble lubricant that can become an aqueous metalworking fluid with improved emulsification stability and processability.
In this specification, HLB refers to the value calculated by the Griffin method.

Examples of nonionic surfactants used in one aspect of the present invention include alkylene glycols, polyoxyalkylene alkyl ethers, polyoxyalkylene aryl ethers, polyoxyalkylene alkylamines (cocoamine alkylene oxide adducts), alkylphenol alkylene oxide adducts, higher alcohol alkylene oxide adducts, polyoxyalkylene fatty acid esters, fatty acid esters of glycerin and pentaerythritol, fatty acid esters of sucrose, fatty acid esters of polyoxyalkylene adducts of polyhydric alcohols, alkyl polyglycosides, fatty acid alkanolamides, and the like.

Among these, from the viewpoint of providing a water-soluble lubricant that can become an aqueous metalworking fluid with improved emulsification stability and processability, it is preferable that the nonionic surfactant used in one aspect of the present invention contains one or more selected from polyoxyalkylene alkyl ethers and polyoxyalkylene alkylamines.
The total content of polyoxyalkylene alkyl ether and polyoxyalkylene alkylamine is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass, based on the total amount (100% by mass) of nonionic surfactant contained in the water-soluble lubricant.

<Anionic surfactants, cationic surfactants>
A water-soluble lubricant according to one embodiment of the present invention may further contain one or more selected from anionic surfactants and cationic surfactants.
Examples of anionic surfactants include polyoxyethylene alkyl ether carboxylic acid, alkylbenzene sulfonic acid, α-olefin sulfonic acid, and salts thereof.
The acid value of the anionic surfactant is preferably 20 to 250 mg KOH/g, more preferably 30 to 200 mg KOH/g, even more preferably 40 to 190 mg KOH/g, and even more preferably 50 to 180 mg KOH/g.
Examples of cationic surfactants include alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkyldimethylbenzylammonium salts.

<Phosphorus-containing compounds>
One embodiment of the present invention contains component (A), and therefore, even without containing a phosphorus-containing compound as a discoloration inhibitor, it can provide good corrosion resistance to various metals. Furthermore, the inventors' studies have shown that phosphorus-containing compounds are components that impair compatibility with FIPG.
In contrast, the water-soluble lubricant according to one aspect of the present invention, because it contains component (A), can maintain good compatibility with FIPG even if it contains a phosphorus-containing compound. However, from the viewpoint of providing a water-soluble lubricant that can prepare an aqueous metalworking fluid with even better compatibility with FIPG, it is preferable that the water-soluble lubricant according to one aspect of the present invention substantially does not contain a phosphorus-containing compound.
Examples of phosphorus-containing compounds include phosphate esters, phosphite esters, thiophosphate esters, and their salts, phosphine compounds, and tricresyl phosphate.

In this specification, "substantially free of phosphorus-containing compounds" means that a provision is made to reject the inclusion of phosphorus-containing compounds for a predetermined purpose, and does not reject the inclusion of phosphorus-containing compounds unintentionally as impurities of other components. However, even considering such unintentional inclusion of phosphorus-containing compounds, from the viewpoint of creating a water-soluble lubricant that can become a water-based metalworking fluid with improved compatibility with FIPG, it is preferable that the content of phosphorus-containing compounds be as low as possible.
The specific amount of phosphorus-containing compound is preferably less than 10 parts by mass, more preferably less than 1 part by mass, even more preferably less than 0.1 parts by mass, even more preferably less than 0.01 parts by mass, and particularly preferably less than 0.001 parts by mass, based on 100 parts by mass of the total amount of component (A) contained in the water-soluble lubricant.

<Other various additives>
A water-soluble lubricant according to one aspect of the present invention may further contain various other additives other than the above components (A) to (E), as necessary, as long as the effects of the present invention are not impaired.
Other types of additives include, for example, petroleum sulfonates, non-phosphorus extreme pressure agents, metal deactivators, emulsifiers, antibacterial agents, defoamers, antioxidants, and oiliness agents.
These various additives may be used individually or in combination of two or more.

In one embodiment of the present invention, the content of each of these additives is appropriately set according to the type and function of each component, but is preferably 0.01 to 40% by mass, more preferably 0.07 to 30% by mass, and even more preferably 0.1 to 20% by mass, based on the total amount of the water-soluble lubricant excluding water (100% by mass).

In one embodiment of the present invention, the content of each of these additives is appropriately set according to the type and function of each component, but is preferably 0.01 to 20% by mass, more preferably 0.03 to 15% by mass, and even more preferably 0.05 to 10% by mass, based on the total amount (100% by mass) of the water-soluble lubricant.

Examples of petroleum sulfonates include calcium sulfonate, sodium sulfonate, and magnesium sulfonate.

Examples of extreme pressure agents other than phosphorus-based agents include chlorine-based extreme pressure agents such as chlorinated paraffin, chlorinated fatty acids, and chlorinated fatty oils; and sulfur-based extreme pressure agents such as sulfurized olefins, sulfurized lard, alkyl polysulfides, and sulfurized fatty acids.

Examples of metal deactivators include benzotriazole, imidazoline, pyrimidine derivatives, and thiadiazole.

Examples of emulsifying agents include unsaturated fatty acid esters such as methyl oleate, ethyl oleate, and propyl oleate; aromatic alcohols such as 2-phenoxyethanol and 2-phenylethyl alcohol; and others.

Examples of antibacterial agents include triazine compounds, alkyl benzimidazole compounds, and metal pyrithione salts.

Examples of defoaming agents include silicone-based defoaming agents, fluorosilicone-based defoaming agents, and polyacrylates.

Examples of antioxidants include amine-based antioxidants such as alkylated diphenylamine, phenylnaphthylamine, and alkylated phenylnaphthylamine; and phenol-based antioxidants such as 2,6-di-t-butylphenol, 4,4'-methylenebis(2,6-di-t-butylphenol), isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate.

Examples of oily agents include alcohols such as lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, and oleyl alcohol.

<Method for manufacturing water-soluble lubricants>
The method for producing a water-soluble lubricant according to one aspect of the present invention is not particularly limited, but it is preferable to have a step of blending component (A) as described above, and optionally components (B) to (E) and various other additives. The order in which each component is blended can be set as appropriate.

<Applications of water-soluble lubricants>
One embodiment of the present invention provides a water-soluble lubricant that has the property of being able to prepare an aqueous metalworking fluid with improved corrosion resistance for various metals.
Therefore, a water-soluble lubricant according to one embodiment of the present invention is preferably used for metalworking of a workpiece.
The workpiece is not particularly limited, and examples include workpieces made of metals as described later.
However, considering the properties of the water-soluble lubricant according to one aspect of the present invention described above, the water-soluble lubricant according to one aspect of the present invention is suitable for use in metalworking of workpieces having components containing non-ferrous metals, and is more suitable for use in metalworking of workpieces having components containing aluminum.

Furthermore, a water-soluble lubricant according to one embodiment of the present invention also has the characteristic of being able to prepare an aqueous metalworking fluid that is also highly compatible with FIPG.
Therefore, one embodiment of the present invention is preferably used in metalworking of a workpiece that is subjected to a treatment using a form-in-place gasket after metalworking.

[Form of water-based metalworking fluid]
One embodiment of the present invention provides an aqueous metalworking fluid which is prepared by using the water-soluble lubricant described above as an embodiment of the present invention as a stock solution and mixing it with diluting water.
The dilution water may be any of the following: distilled water, deionized water, tap water, industrial water, etc.

When preparing an aqueous metalworking fluid, it is preferable to adjust the amount of diluent water used to achieve the desired dilution concentration.
The dilution concentration of the aqueous metalworking fluid in one embodiment of the present invention is preferably 1 to 50% by volume, more preferably 3 to 40% by volume, and even more preferably 5 to 30% by volume.
In this specification, the "dilution concentration of the aqueous metalworking fluid" refers to the value calculated from the following formula.
• "Dilution concentration (volume %) of water-based metalworking fluid" = [Volume of water-soluble lubricant before dilution] / [[Volume of water-soluble lubricant before dilution] + [Volume of dilution water]] × 100

[Uses of water-based metalworking fluids and metalworking methods]
A preferred embodiment of the present invention provides an aqueous metalworking fluid that exhibits superior corrosion resistance to various metals and compatibility with FIPG compared to conventional aqueous metalworking fluids, and can be suitably used in metalworking.

The workpiece to be processed using the aqueous metalworking fluid according to one embodiment of the present invention is not particularly limited, but examples include workpieces made of metals selected from the group consisting of iron, titanium, aluminum, titanium alloys, alloy steels, nickel-based alloys, niobium alloys, tantalum alloys, molybdenum alloys, tungsten alloys, stainless steel, aluminum alloys, and high-manganese steel. Among these, workpieces containing non-ferrous metal components are particularly suitable, and workpieces containing aluminum components are even more suitable.

Therefore, the present invention may also provide the following [1] and [2].
[1] A method of use for applying the aqueous metalworking fluid according to one embodiment of the present invention described above to the processing of a workpiece.
[2] A metalworking method comprising the step (1) of processing a workpiece by applying an aqueous metalworking fluid according to one embodiment of the present invention described above.

The workpiece described in [1] and [2] above is as described above, but a workpiece having a component containing a non-ferrous metal is preferred, and a workpiece having a component containing aluminum is more preferred. According to the methods described in [1] and [2] above, corrosion of the workpiece can be effectively suppressed.

In the above [1] and [2], examples of processing of the workpiece include cutting, grinding, punching, polishing, drawing, drawing, and rolling.
Furthermore, in the method of use described in [1] above and the metalworking method described in [2] above, the water-based metalworking fluid is used by mixing diluted water with the water-soluble lubricant according to one embodiment of the present invention described above, supplying it to the workpiece, and bringing it into contact with the workpiece. The water-based metalworking fluid lubricates the space between the workpiece and the workpiece tool. It is also used for chip removal, rust prevention of the workpiece, and cooling of the tool and the workpiece.

In addition, as described above, one embodiment of the present invention of an aqueous metalworking fluid exhibits excellent compatibility with FIPG.
Therefore, in the method of use described in [1] above, it is preferable that the workpiece is a workpiece that undergoes a process using a form-in-place gasket after metal processing.
Furthermore, in the metal processing method described in [2] above, it is preferable to have a step (2) in which a process using a form-in-place gasket is performed after step (1).
According to one embodiment of the present invention, even when a water-based metalworking fluid is applied to a workpiece and a treatment using a form-in-place gasket is performed, the fit of the FIPG can be improved, and the workability of the metalworking process can be further enhanced.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited in any way by these examples.
In the following examples, the methods for measuring and calculating the physical properties are as shown below.
(1) Kinematic viscosity and viscosity index were measured and calculated in accordance with JIS K2283:2000.
(2) HLB
It was calculated based on the Griffin method.
(3) Acid value (indicator photometric titration method)
Measurements were taken in accordance with JIS K2501:2003 (Indicator photometric titration method).
(4) Base number (hydrochloric acid method)
Measurements were taken in accordance with JIS K2501:2003 (hydrochloric acid method).

The details of each component used in the preparation of the water-soluble lubricants in the following examples, comparative examples, and reference examples are as follows.
<Compounds under consideration>
Glucono delta-lactone: A compound represented by the following formula (a-i), which corresponds to a cyclic compound (A1).
Dodecenyl succinic anhydride: A compound represented by the following formula (a-ii), which corresponds to a cyclic compound (A2).
• Gluconic acid: A compound represented by the following formula (iii).
Lactobionic acid: A compound represented by the following formula (iv).
Trehalose: A compound represented by the following formula (v).
Polyoxyethylene alkyl ether phosphate

<Base oil, various additives>
Naphthenic mineral oil: Naphthenic mineral oil with a kinematic viscosity of 27.77 ^mm² /s at 40°C and a viscosity index of 2.0.
• Amine mixture (1): A mixture of N-methyldiethanolamine and N-cyclohexyldiethanolamine.
• Amine mixture (2): A mixture of amines consisting of monoisopropanolamine, dicyclohexylamine, and hexahydro-1,3,5-tris-(2-hydroxyethyl)triazine.
• Fatty acid mixture (1): A mixture of fatty acids consisting of trimethylhexanoic acid, sebacic acid, and dodecanediic acid. The acid value of the aliphatic mixture (1) is 19.3 mg KOH/g.
• Fatty acid mixture (2): A fatty acid mixture comprising dodecanediic acid, neodecanoic acid, tall oil fatty acid, and ricinoleic acid polymerized fatty acid. The acid value of the aliphatic mixture (2) is 83.3 mg KOH/g, and the hydroxyl value of the aliphatic mixture (2) is 3.2 mg KOH/g.
• Metal deactivator: Benzotriazole.
• Antibacterial agent: 1,2-benzoisothiazole-3(2H)-one.
Nonionic surfactant: polyoxyalkylene alkyl ether, HLB = 12.7.
• Defoaming agent: Silicone-based defoaming agent.

Examples 1-16, Comparative Examples 1-14, Reference Examples 1-4
Water-soluble lubricants were prepared by adding and mixing various components of the types shown in Tables 1 to 4 in the amounts shown in the same tables. Details of each component used in the preparation of the water-soluble lubricants are as described above. The water-soluble lubricants prepared in Examples 1 to 8, Comparative Examples 1 to 7, and Reference Examples 1 to 2 correspond to Type A3 solution-type oils specified in JIS K2241:2017, while the water-soluble lubricants prepared in Examples 9 to 16, Comparative Examples 8 to 14, and Reference Examples 3 to 4 correspond to Type A1 emulsion-type oils specified in the same standard.

The following metal corrosion tests were conducted on the prepared water-soluble lubricant. The test results are shown in Tables 1 to 4.
[Aluminum discoloration test]
The water-soluble lubricants prepared in the examples and comparative examples were diluted 20-fold with deionized water to prepare a 5% by volume aqueous metalworking solution.
Aluminum alloy specimens, A6061 and ADC12, polished on both sides, were placed in two screw-top tubes. The prepared aqueous metalworking solution was then poured into each tube until approximately half of the specimen was submerged. The tubes were then capped and left to stand for two hours at 60°C.
After standing, the presence or absence of discoloration in the parts of each test specimen that were immersed in the aqueous metalworking solution (immersed portion) and the parts that were not immersed (gas phase portion) was visually compared with the test specimen before immersion, and the aluminum discoloration resistance was evaluated according to the following criteria.
A: No discoloration was observed in either the immersed or gas phase portion, demonstrating excellent resistance to aluminum discoloration.
B: No discoloration was observed in either the immersed portion or the gas phase portion, but discoloration was observed in the other portion.
C: Discoloration was observed in both the immersed and gas phase portions.

Tables 1 to 4 show that the aqueous metalworking fluids prepared by diluting the water-soluble lubricants in Examples 1 to 16 with deionized water showed no discoloration on either the A6061 or ADC12 test specimens, similar to the water-soluble lubricants in Reference Examples 1 to 4, demonstrating excellent resistance to aluminum discoloration.
On the other hand, the aqueous metalworking fluids prepared by diluting the water-soluble lubricants prepared in Comparative Examples 1 to 14 with deionized water showed discoloration in at least one of the A6061 and ADC12 test pieces, indicating a problem with aluminum discoloration resistance.

Examples 17-18, Reference Examples 5-6
Water-soluble lubricants were prepared by adding and mixing various components of the types shown in Table 5 in the amounts shown in the same table. Details of each component used in the preparation of the water-soluble lubricants are as described above. The prepared water-soluble lubricants correspond to the A1 type emulsion-type oil specified in JIS K2241:2017.
The prepared water-soluble lubricant was diluted 10 times with deionized water to form a 10% by volume aqueous metalworking fluid, and the following FIPG conformity test was performed.

[FIPG Conformity Testing]
<Test specimen>
Two A1050 plates (100 mm long x 25 mm wide x 1.6 mm thick) were prepared. On one side of each A1050 plate, a 10 mm long x 25 mm wide area was polished with 240-grit sandpaper using a pressing force of 5 N, making 10 back-and-forth strokes in both the vertical and horizontal directions to form an FIPG coated area. After that, the plate was immersed in acetone and ultrasonically cleaned to create the test specimen.
<FIPG>
TB1292D/TB1293D (Product name, ThreeBond Co., Ltd., two-component silicone liquid gasket)

<Operating Procedure>
(i) Two test specimens were immersed in the aqueous metalworking fluid to be measured for 5 seconds, then placed in a constant temperature chamber at 23°C and 50% relative humidity with the length of the test specimens facing vertically, and left to stand for 1 hour in the same environment to dry the test specimens.
(ii) FIPG was applied to a FIPG-coated area of one test specimen measuring 10 mm vertically x 25 mm horizontally to form a coating film with a drying thickness of 1.0 mm. The FIPG-coated area of the other test specimen was then bonded to this coating film, and the two specimens were left standing in a constant temperature chamber at 23°C and 50% relative humidity for 24 hours to cure the FIPG. In this way, a tensile test sample (1) was prepared, as shown in Figure 1, in which two test specimens (11) and (12) were bonded together via FIPG (20).
(iii) The tensile test sample (1) was placed in the testing machine, and the ends of the two test pieces (11) and (12) were fixed. The maximum shear stress was measured when the samples were pulled in directions 180° apart vertically under the following tensile test conditions. The measurement was performed seven times, and the average value was taken as the maximum shear stress when using the aqueous metalworking fluid being measured. The average values of the maximum shear stress are shown in Table 5.
Furthermore, when the two test pieces were subjected to the operations described in (ii) and (iii) without immersion in the aqueous metalworking fluid described in (i) above, and the average value of the maximum shear stress was calculated, it was found to be "0.53 MPa".
(Tensile test conditions)
• Testing machine: Precision universal testing machine Autograph AG-Xplus (product name, manufactured by Shimadzu Corporation)
• Number of trials: 7 • Tensile speed: 1.25 mm/min • Preload: 3N
Sampling time: 0.2 seconds

<FIPG Conformity Assessment>
The FIPG conformity assessment was performed on the average value of the measured maximum shear stress according to the following criteria. The evaluation results are shown in Table 5.
A: The average value of the maximum shear stress is 0.35 MPa or higher.
• F: The average value of the maximum shear stress is less than 0.35 MPa.

As shown in Table 5, the aqueous metalworking fluids prepared in Examples 17-18 had an average maximum shear stress of 0.35 MPa or higher, demonstrating good compatibility with FIPG.
On the other hand, as shown in Reference Example 5, a water-based metalworking fluid prepared by diluting a water-soluble lubricant containing polyoxyethylene alkyl ether phosphate showed good resistance to aluminum discoloration, as shown in Tables 2 and 4, but poor FIPG compatibility.

1. Tensile test samples 11, 12. Test specimens 20. FIPG

Claims (14)

A water-soluble lubricant containing a cyclic compound (A) having a ring structure (α) that includes at least one substructure represented by the following formula (i) or (ii) ,

(In the above formula, * indicates the bonding position.)
A water-soluble lubricant in which component (A) contains one or more cyclic compounds (A1) having a ring structure (α1) represented by the following formula (a-1) and cyclic compounds (A2) having a ring structure (α2) represented by the following formula (a-2).

(At least one hydrogen atom in formula (a-1) above is substituted with a substituent selected from the group consisting of a hydroxyl group, a C1-C5 alkyl group, a C1-C5 alkyl group having a hydroxyl group, a C1-C5 alkenyl group, a cycloalkyl group, and an aryl group.)
Furthermore, at least one hydrogen atom in formula (a-2) above is substituted with a substituent selected from the group consisting of a hydroxyl group, a C1-C30 alkyl group, a C1-C30 alkenyl group, a C1-C30 alkyl group having a hydroxyl group, a cycloalkyl group, and an aryl group. At least one hydrogen atom in formula (a-1) is substituted with a substituent selected from the group consisting of a hydroxyl group, a C1-C5 alkyl group, a C1-C5 alkyl group having a hydroxyl group, and a C1-C5 alkenyl group.
At least one hydrogen atom in formula (a-2) is substituted with a substituent selected from the group consisting of a hydroxyl group, a C1-C30 alkyl group, a C1-C30 alkenyl group, or a C1-C30 alkyl group having a hydroxyl group.
The water-soluble lubricant according to claim 1. Component (A1) is compound (A11) represented by the following formula (a-11),
Component (A2) is compound (A21) represented by the following formula (a-21).
The water-soluble lubricant according to claim 1.

(R in the above formula (a-11) ^A Each of these is independently a hydroxyl group, a C1-C5 alkyl group, a C1-C5 alkyl group having a hydroxyl group, a C1-C5 alkenyl group, a cycloalkyl group, or an aryl group.
Also, R in the above formula (a-21) ^A (These are a hydroxyl group, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 1 to 30 carbon atoms, an alkyl group having 1 to 30 carbon atoms with a hydroxyl group, a cycloalkyl group, or an aryl group.) R in formula (a-11) ^A However, each is independently a hydroxyl group, a C1-C5 alkyl group, a C1-C5 alkyl group having a hydroxyl group, or a C1-C5 alkenyl group.
R in formula (a-21) ^A However, it is a hydroxyl group, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 1 to 30 carbon atoms, or an alkyl group having 1 to 30 carbon atoms with a hydroxyl group.
The water-soluble lubricant according to claim 3. A water-soluble lubricant according to any one of claims 1 to 4, classified as type A1, type A2, or type A3 as defined in JIS K2241:2017. A water-soluble lubricant according to any one of claims 1 to 5, substantially free of phosphorus-containing compounds. A water-soluble lubricant according to any one of claims 1 to 6, wherein the content of component (A) is 0.1 to 10.0% by mass, based on the total amount of the water-soluble lubricant excluding water. Furthermore, a water-soluble lubricant according to any one of claims 1 to 7, further containing water (B). A water-soluble lubricant according to any one of claims 1 to 8, used for metalworking of workpieces. The water-soluble lubricant according to claim 9, wherein the workpiece is a workpiece that undergoes treatment using a form-in-place gasket after the metal processing. The water-soluble lubricant according to claim 9 or 10, wherein the workpiece has a component containing aluminum. A water-based metalworking fluid comprising a water-soluble lubricant according to any one of claims 1 to 11, blended with diluting water. A metalworking method comprising step (1) of processing a workpiece by applying the aqueous metalworking fluid described in claim 12. The metalworking method according to claim 13, further comprising step (2) of performing a process using a form-in-place gasket after step (1).