JP7253338B2 - Defoaming evaluation method, water-based lubricant manufacturing method, water-based lubricant, and coolant - Google Patents

Description

TECHNICAL FIELD The present invention relates to an antifoaming evaluation method, a method for producing a water-based lubricant, a water-based lubricant, and a coolant.

In the field of machining such as cutting and grinding, working fluids are used for the purposes of improving machining efficiency, controlling friction between machining materials and tools, extending tool life, and removing chips.

Conventionally, oil-based lubricants containing an oily base oil as a lubricating component have been used as working fluids.
In recent years, from the viewpoint of environmental load reduction, safety improvement, and cooling performance, working fluids (hereinafter referred to as " coolant) is being used.
The water-based lubricant, for example, contains 10 to 80% by mass of mineral oil or synthetic oil having an aniline point of 85 to 110° C. as a lubricating component, further contains 1 to 6% by mass of a primary alkanolamine, and 4 to 4% of an organic acid compound. A water-based lubricant containing 20% by weight, 1 to 10% by weight of a nonionic surfactant with an HLB of 1 to 6 calculated from Griffin's formula, and water is known (Patent Document 1). The water-based lubricant is diluted with water and used as a coolant.

A machining fluid used in a machining center or the like is put into a tank, supplied from the tank to a machining chamber nozzle by a pump, and discharged from the nozzle. After being supplied to the cutting tool and the grinding tool, the machining fluid discharged from the nozzle is discharged from the machining chamber together with chips and the like, and after the chips and the like are removed, it returns to the tank again. That is, the working fluid is circulated during cutting and grinding of the workpiece.

JP 2014-105232 A

By the way, when a coolant is employed as a machining fluid used in a machining center or the like, the coolant flows down into the tank, which agitates the machining fluid in the tank and causes violent bubbling. Specifically, when the working fluid in the tank is agitated, air bubbles are generated in the working fluid, and the air bubbles float to the surface of the working fluid and become bubbles. As a result, foam generated on the liquid surface overflows the tank, and part of the coolant may overflow from the tank.

It is well known that foam can occur on the liquid surface of water containing surfactants. Foam generation in the coolant is also believed to be due to the presence of surfactants.
Here, from the viewpoint of suppressing coolant from overflowing from the tank, it is considered important to grasp the stability of generated foam. However, a method for predicting the stability of generated foam has not yet been established systematically, and much depends on experience.
It is considered that the stability of generated foam depends on the defoaming properties. Therefore, it is considered that the stability of generated foam can be grasped by paying attention to defoaming properties. However, a method for systematically predicting defoaming properties has not yet been established.

The present invention has been made in view of such problems, a defoaming evaluation method that can systematically predict the defoaming property of water containing a surfactant, and a method for evaluating defoaming properties when diluted with water and used as a coolant It is an object of the present invention to provide a method for producing a water-based lubricant having excellent defoaming properties, a water-based lubricant having excellent defoaming properties when diluted with water and used as a coolant, and a coolant having excellent defoaming properties.

The present inventors have made intensive studies to solve the above problems. As a result, using the measurement results of the dynamic surface tension of water containing surfactants, the maximum dynamic surface tension decrease rate was calculated using a function showing the relationship between surface life and dynamic surface tension, and the maximum The inventors have found that it is possible to systematically predict the defoaming properties of surfactant-containing water by using the dynamic surface tension reduction rate as an index, and have completed the present invention.

That is, the present invention relates to the following [1] to [4].
[1] Using the results of measuring the dynamic surface tension of water containing a surfactant, the maximum dynamic surface tension An antifoaming property evaluation method comprising calculating a decreasing speed (V _max ) and evaluating the antifoaming property of water containing the surfactant using the maximum dynamic surface tension decreasing speed (V _max ) as an index.
γ(t)= _γm +( _γ0 − _γm )/{1+(t/t ^* ) ⁿ } (1)
(In the above formula (1), _γ0 is the surface tension of water, _γm is the meso-equilibrium value of the surface tension, and t ^* is the time when γ(t) becomes intermediate between _γ0 and _γm . Yes, and n is a positive number.)
[2] The absolute value of the maximum dynamic surface tension decrease rate (V _max ) calculated based on the above formula (1) showing the relationship between the surface life t and the dynamic surface tension γ(t) is diluted with water. A method for producing a water-based lubricant, comprising the step of mixing a lubricating component and a surfactant so that the ratio is less than 1.
[3] The maximum calculated based on the above formula (1) showing the relationship between the surface life t and the dynamic surface tension γ (t) when it contains a lubricating component and a surfactant and is diluted with water A water-based lubricant having a dynamic surface tension reduction rate (V _max ) of less than 1 in absolute value.
[4] The maximum dynamic surface tension calculated based on the above formula (1) containing a lubricating component, water, and a surfactant and showing the relationship between the surface life t and the dynamic surface tension γ(t) A coolant having an absolute value of decline rate (V _max ) of less than one.

According to the defoaming property evaluation method of the present invention, it becomes possible to systematically predict the defoaming property of water containing a surfactant. Moreover, according to the method for producing a water-based lubricant of the present invention, it is possible to produce a water-based lubricant that is excellent in defoaming properties when diluted with water and used as a coolant. Furthermore, the water-based lubricant of the present invention has excellent defoaming properties when diluted with water and used as a coolant. Moreover, the coolant of the present invention is excellent in defoaming properties.

It is a process schematic diagram of the antifoaming evaluation method of the present invention. FIG. 4 is a diagram showing regions related to the state of adsorption of surfactant molecules to the gas-liquid interface obtained by dynamic surface tension measurement. 1 is a schematic diagram of a circulation-type Ross-Miles test apparatus used in the present example. FIG. (A) Dynamic surface tension measurement results, (B) Absolute value of maximum dynamic surface tension decrease rate (V _max ) and foam height when various types of fatty acids are changed for monoisopropanolamine (MIPA) is a diagram showing the relationship of (A) Measurement results of dynamic surface tension, (B) Relationship between absolute value of maximum dynamic surface tension decrease rate (V _max ) and foam height when various types of amines are changed for decanoic acid. It is a diagram. (A) Dynamic surface tension measurement results, (B) relationship between absolute value of maximum dynamic surface tension decrease rate (V _max ) and foam height when various types of amines are changed for oleic acid. It is a diagram. FIG. 4 shows the relationship between foam height and static surface tension versus foam height for all systems and amines studied in the examples.

[Defoaming evaluation method of the present invention]
The antifoaming evaluation method of the present invention uses the results of measuring the dynamic surface tension of water containing a surfactant, and is based on the following formula (1) showing the relationship between the surface life t and the dynamic surface tension γ(t). Then, the maximum dynamic surface tension reduction rate (V _max ) is calculated, and the antifoaming property of water containing the surfactant is evaluated using the maximum dynamic surface tension reduction rate (V _max ) as an index.
γ(t)= _γm +( _γ0 − _γm )/{1+(t/t ^* ) ⁿ } (1)
(In the above formula (1), _γ0 is the surface tension of water, _γm is the meso-equilibrium value of the surface tension, and t ^* is the time when γ(t) becomes intermediate between _γ0 and _γm . Yes, and n is a positive number.)

In order to systematically predict the foam stability of surfactant-containing water, the present inventors focused on the "defoaming properties" of surfactant-containing water and conducted extensive studies.
First, evaluation of antifoaming properties based on "static surface tension" was examined. As a result, there was a tendency that the lower the static surface tension, the poorer the defoaming properties and the more likely the generated foam was to be stabilized. Also, no correlation was obtained between defoaming properties and static surface tension. From this, it was considered difficult to predict the defoaming properties of surfactant-containing water based on the static surface tension in the equilibrium state.
Then, the present inventors next examined evaluation of defoaming properties based on "dynamic surface tension". However, since the dynamic surface tension fluctuates with respect to the surface life, it is not possible to specify the dynamic surface tension value to be referred to when evaluating the defoaming property, and simply use the measurement results of the dynamic surface tension. It was considered difficult to evaluate antifoaming properties only by
Therefore, the inventors of the present invention conducted further extensive studies. As a result, a correlation was observed between the maximum dynamic surface tension decrease rate (V _max ), which can be calculated from the function showing the relationship between the surface life t and the dynamic surface tension γ(t), and the antifoaming property. , The larger the maximum dynamic _surface tension decrease rate (V _max ), the poorer the defoaming property, so the foam is more likely to be stabilized. was found to be difficult to stabilize. The present inventors believe that by utilizing this fact, it is possible to systematically evaluate defoaming properties of water containing surfactants, using the maximum dynamic surface tension decrease rate (V _max ) as an index. and completed the present invention.

Hereinafter, the antifoaming evaluation method of the present invention will be described in detail with reference to the process schematic shown in FIG.

<Measurement of dynamic surface tension (S1)>
In the antifoaming evaluation method of the present invention, first, the dynamic surface tension of water containing a surfactant is measured (S1).
"Dynamic surface tension" means the surface tension from the formation of the gas-liquid interface in the liquid by introducing the gas into the liquid until the surface tension reaches equilibrium.

The dynamic surface tension measurement method is such that the maximum dynamic surface tension decrease rate (V _max ) can be calculated from the function showing the relationship between the surface life t and the dynamic surface tension γ(t), which will be described later. , is not particularly limited as long as it is possible to acquire measurement data. Specific methods for measuring dynamic surface tension include, for example, the maximum bubble pressure method, the vibrating jet method, and the meniscus method. From the viewpoint of measuring the dynamic surface tension with reproducibility, it is preferable to adopt the maximum bubble pressure method as the method for measuring the dynamic surface tension.

In the maximum bubble pressure method, a capillary is inserted into the liquid to be measured, gas (air) is discharged from the tip of the capillary, and bubbles are generated at the tip of the capillary to form a gas-liquid interface in the liquid. , from the difference between the pressure (maximum pressure) when the bubble generated at the tip of the capillary becomes a hemisphere with a radius equal to the inner radius of the capillary (maximum pressure) and the pressure of the liquid near the capillary (hydrostatic pressure), the dynamic surface It is a method of calculating tension.
In the maximum bubble pressure method, since gas is continuously sent into the liquid from the tip of the capillary, it is possible to constantly generate new bubbles at the tip of the capillary to form a gas-liquid interface while removing dirt adsorbed to the tip of the capillary. can. Therefore, the dynamic surface tension can be obtained by measuring the maximum pressure with high precision without being affected by dirt on the tip of the capillary.
The dynamic surface tension γ is calculated by the following formulas (A) and (B).
γ={(rΔP)/2}×f (A)
ΔP=P _max -P _min (B)
In equations (A) and (B) above, r is the inner radius of the capillary, P _max is the maximum pressure, P _min is the hydrostatic pressure, and f is formed by the gas ejected from the tip of the capillary. It is a correction coefficient for the surface shape of a hemispherical bubble.

Here, in order to calculate the maximum dynamic surface tension decrease rate (V _max ) from the function showing the relationship between the surface life t and the dynamic surface tension γ(t), which will be described later, the dynamic surface tension γ is the surface A plurality of measurements are performed while changing the lifetime t.
The surface life t is the time required for a bubble formed by the gas discharged from the tip of the capillary to become hemispherical with a radius equal to the inner radius of the capillary, and is controlled by the gas supply speed to the capillary. can be done.
As an apparatus for measuring a plurality of dynamic surface tensions γ by changing the surface life t, for example, a Bubble Pressure dynamic surface tension meter BP100 manufactured by KRUSS can be used.

<Calculation of Maximum Dynamic Surface Tension Decreasing Rate (V _max ) (S2)>
In the antifoaming evaluation method of the present invention, the measurement results in the above step S1 are used, and the maximum dynamic surface tension Calculate the rate of decline (V _max ).
γ(t)= _γm +( _γ0 − _γm )/{1+(t/t ^* ) ⁿ } (1)
(In the above formula (1), _γ0 is the surface tension of water, _γm is the meso-equilibrium value of the surface tension, and t ^* is the time when γ(t) becomes intermediate between _γ0 and _γm . Yes, and n is a positive number.)

The above formula (1) is calculated according to the method of Rosen et al. Sci., 139, 397 (1990), Y. Hua and MJ Rosen, J. Colloid Interface Sci., 141, 180 (1991)).
In the above formula (1), "γ _m is the meso-equilibrium value of surface tension" is the value when the change in surface tension for 30 seconds is 1 N·m ⁻¹ . Also, the “surface tension of water” of γ ₀ is assumed to be 72.8 mN·m ⁻¹ .

Although the method for calculating the maximum dynamic surface tension decreasing rate (V _max ) based on the above formula (1) is not particularly limited, it can be calculated, for example, by the following procedure.
First, the "surface tension decreasing rate" is obtained by first-order differentiating the above formula (1) with the surface life t. The following equation (2) is a first-order differential equation obtained by first-differentiating the above equation (1) with the surface life t.
dγ(t)/dt=−(γ ₀ −γ _m ){n(t/t ^* ) ⁿ⁻¹ /t ^* }/{1+(t/t ^* ) ⁿ } ² (2)

Then, the "maximum dynamic surface tension decreasing rate (V _max )" is calculated from the above equation (2). The calculation method is not particularly limited, but since the above formula (2) takes the maximum value at t = t ^* , from the following formula (3) obtained by substituting t = t ^* into the above formula (2) A maximum dynamic surface tension decrease rate (V _max ) can be calculated.
dγ(t ^* )/dt=−n( _γ0 − _γm )/4t ^* = _Vmax (3)

Here, FIG. 2 shows a sigmoidal curve regarding the time dependence of surface tension obtained by dynamic surface tension measurement. As shown in FIG. 2, the sigmoidal curve obtained by dynamic surface tension measurement can be divided into four regions, each region having a different adsorption state of surfactant molecules.
Specifically, region I is the region until adsorption of surfactant molecules to the gas-liquid interface begins. Region II is a region where surfactant molecules are adsorbed on the gas-liquid interface, and the surface tension is rapidly reduced. Region III is the quasi-equilibrium region, where the adsorption of surfactant molecules to the gas-liquid interface ceases. Region IV is the equilibrium region, where adsorption of surfactant molecules on the air-liquid interface reaches equilibrium. The surface tension values in region IV are equivalent to the static surface tension values.
In FIG. 2, the horizontal axis is the logarithm of the surface life t, and the vertical axis is the surface tension at each surface life.
Measuring the dynamic surface tension yields a sigmoidal curve as shown in FIG. Here, in the above formula (3), t ^* and n have relational expressions such as the following formulas (4) and (5), respectively, so that t _i and Each can be calculated by using _tm . By substituting the calculated t ^* and n into the above equation (3), V _max can be calculated.
logt _i =logt ^* -(1/n) (4)
_logtm = logt ^* + (1/n) (5)
In equation (4) above, t _i is the surface lifetime at which region II begins. Also, in the above formula (5), _tm is the surface lifetime at which region III begins.

<Defoaming property evaluation (S3) using maximum dynamic surface tension decrease rate (V _max ) as an index>
In the defoaming property evaluation method of the present invention, the defoaming property of water containing a surfactant is evaluated using the maximum dynamic surface tension decrease rate (V _max ) calculated in step S2 as an index.

According to studies by the present inventors, it has been confirmed that there is a certain correlation between the maximum dynamic surface tension decreasing rate (V _max ) and defoaming properties in water containing surfactants. Therefore, for water containing a surfactant, the maximum dynamic surface tension reduction rate (V _max ) is used as an index, and for example, the larger the absolute value of the maximum dynamic surface tension reduction rate (V _max ), the poorer the defoaming property The foam is easily stabilized, and the smaller the absolute value of the maximum dynamic surface tension decreasing rate (V _max ), the better the defoaming properties, so it is possible to qualitatively evaluate that the foam is less likely to be stabilized.
In addition, as described above, it has been confirmed that there is a certain correlation between the maximum dynamic surface tension decrease rate (V _max ) and the defoaming property for water containing a surfactant. Defoaming performance can also be quantitatively evaluated based on the previously obtained correlation between the dynamic surface tension decrease rate (V _max ) and the measurement result of defoaming performance. Specifically, for water containing a surfactant, a correlation function is obtained based on the maximum dynamic surface tension decrease rate (V _max ) and the measurement results of defoaming properties, and calculated from the dynamic surface tension measurement results. Defoaming property may be quantitatively evaluated by substituting the maximum dynamic surface tension decreasing rate (V _max ) into the correlation function.

Here, when the antifoaming property of water containing a surfactant is excellent, it can be evaluated that foam is difficult to stabilize, and overflow from a tank is unlikely to occur when used as a coolant in a machining center or the like. Conversely, when the antifoaming property of the water containing the surfactant is poor, it can be evaluated that the foam tends to be stabilized and overflow from the tank is likely to occur when used as a coolant in a machining center or the like.
In the antifoaming evaluation method of one aspect of the present invention, using this, a specific standard for the maximum dynamic surface tension decrease rate (V _max ) is determined, and whether or not overflow occurs based on the standard can be evaluated more rigorously.
Specifically, in the antifoaming property evaluation method of one aspect of the present invention, it is preferable to set a standard for the absolute value of the maximum dynamic surface tension decrease rate (V _max ) and set the standard to “less than 1”.
According to studies by the present inventors, it has been confirmed that if the absolute value of the maximum dynamic surface tension decrease rate (V _max ) is less than 1, overflow does not occur in the circulatory Loss-Miles test. On the other hand, if the absolute value of the maximum dynamic surface tension decrease rate (V _max ) is 1 or more, it was confirmed that overflow occurred in the circulatory Loss-Miles test.
As used herein, the term "circulation-type Loss-Miles test" refers to a Ross-Miles test in which the test sample is circulated, which is performed by a Ross-Miles test apparatus equipped with liquid feeding means such as a gear pump. , in particular, means the test method described in the Examples.

[Method for producing water-based lubricant of the present invention]
In the method for producing a water-based lubricant of the present invention, the maximum dynamic surface tension decrease rate (V _max ) calculated based on the above formula (1) showing the relationship between the surface life t and the dynamic surface tension γ(t) is less than 1 when diluted with water.

<Lubricant component>
The lubricating component used in the method for producing a water-based lubricant of the present invention is not particularly limited as long as it is a lubricating component generally used in water-based lubricants, and may be an oil-based lubricating component or an aqueous lubricating component.
For example, when the water-based lubricant is a type A1 emulsion-type water-based lubricant defined in JIS 2241:2000, the lubricating component is one or more selected from oil-based lubricating components such as mineral oil and fatty oil. Used.
When the water-based lubricant is a type A2 soluble water-based lubricant defined in JIS 2241:2000, the lubricating component is one or more selected from oil-based lubricating components such as mineral oil and fatty oil. . However, instead of one or more selected from oil-based lubricating components, one or more selected from water-based lubricating components such as polyalkylene glycol may be used.
Further, when the water-based lubricant is a solution-type water-based lubricant of type A3 specified in JIS 2241: 2000, the lubricating component is selected from water-based lubricating components such as polyalkylene glycol. be done.

When the water-based lubricant is the A1 type emulsion type, the amount of the oil-based lubricating component is usually 50 to 80% by mass based on the total amount of the water-based lubricant.
When the water-based lubricant is the A2 type soluble type, the amount of the oil-based lubricating component is usually 0 to 30% by mass based on the total amount of the water-based lubricant. When the oil-based lubricating component is 0% by mass, an aqueous lubricating component is blended. The blending amount of the aqueous lubricating component is usually 5 to 30% by mass based on the total amount of the aqueous lubricant.
When the water-based lubricant is the A3 type solution type, the amount of the water-based lubricating component is usually 5 to 30% by mass based on the total amount of the water-based lubricant.

<Surfactant>
A surfactant used in the method for producing a water-based lubricant according to one embodiment of the present invention contains a fatty acid amine salt.
The fatty acid amine salt is one or more selected from (a) to (c) below.
(a) Fatty acid amine salt of one or more selected from fatty acids having 6 to 12 carbon atoms and one or more selected from primary amines having one alkanol group having 1 to 4 carbon atoms (b) carbon One or more selected from fatty acids having a number of 16 to 20 and a tertiary amine having three alkanol groups having 1 to 4 carbon atoms (the three alkanol groups may be the same or different, and the number of carbon atoms is 3 or more may have a linear structure or a branched structure.) fatty acid amine salt with one or more selected from (c) 1 selected from fatty acids having 16 to 20 carbon atoms and a tertiary amine having two alkanol groups having 1 to 4 carbon atoms and one hydrocarbon group having 1 to 8 carbon atoms (the two alkanol groups may be the same or different The alkanol group having 3 or more carbon atoms may have a linear or branched structure, and the hydrocarbon group having 1 to 8 carbon atoms may be a linear or branched aliphatic hydrocarbon group. or an alicyclic hydrocarbon group).
In addition, in this specification, the number of carbon atoms of the fatty acid is the number of carbon atoms including the carbon atoms of the carboxyl group.
By using any one of the fatty acid amine salts (a) to (c) above, the absolute value of the maximum dynamic surface tension decrease rate (V _max ) is adjusted to less than 1 when the water-based lubricant is diluted with water. easy to do

In one aspect of the present invention, the fatty acid having 6 to 12 carbon atoms may be either saturated fatty acid or unsaturated fatty acid, preferably unsaturated fatty acid. Further, the fatty acid having 6 to 12 carbon atoms may be linear or branched.
Specific examples of fatty acids having 6 to 12 carbon atoms include hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, methylhexanoic acid, dimethylhexanoic acid, trimethylhexanoic acid and the like, preferably hexanoic acid and nonanoic acid. , trimethylhexanoic acid.
Fatty acids having 6 to 12 carbon atoms may be used alone or in combination of two or more.

In one aspect of the present invention, the fatty acid having 16 to 20 carbon atoms may be a saturated fatty acid or an unsaturated fatty acid. Further, the fatty acid having 16 to 20 carbon atoms may be linear or branched.
Specific examples of fatty acids having 16 to 20 carbon atoms include hexadecanoic acid, hexadecenoic acid, heptadecanoic acid, octadecanoic acid, oleic acid, and eicosanoic acid, with oleic acid being preferred.
Fatty acids having 16 to 20 carbon atoms may be used alone or in combination of two or more.

In one aspect of the present invention, the primary amine having one alkanol group having 1 to 4 carbon atoms is preferably one or more monoalkanolamines selected from monoethanolamine and monoisopropanolamine.

In one aspect of the present invention, the tertiary amine having three alkanol groups having 1 to 4 carbon atoms is preferably one or more trialkanolamines selected from triethanolamine and triisopropanolamine.
In one aspect of the present invention, the tertiary amine having two alkanol groups having 1 to 4 carbon atoms and one hydrocarbon group having 1 to 8 carbon atoms is preferably N-cyclohexyldiethanolamine and N- One or more dialkanolamines selected from methyldiethanolamine.

The amount of the surfactant to be blended is not particularly limited, and may be a normal blending amount for water-based lubricants.
For example, when the water-based lubricant is the A1 type emulsion type, the amount of the surfactant to be blended is usually 10 to 40% by mass based on the total amount of the water-based lubricant.
When the water-based lubricant is the A2 type soluble type, the amount of the surfactant compounded is usually 5 to 20% by mass based on the total amount of the water-based lubricant.
When the water-based lubricant is the A3 type solution type, the amount of the water-based lubricating component is usually 5% by mass or less based on the total amount of the water-based lubricant.
Surfactants contained in water-based lubricants cause foaming and cause overflow in tanks such as machining centers. The antifoaming properties of the coolant prepared by this process are excellent, and overflow can be suppressed.
In addition, in the method for producing a water-based lubricant of the present invention, additives that are commonly added to water-based lubricants may be blended within a range that does not impair the effects of the present invention.

When the water-based lubricant is diluted with water to prepare the coolant, the dilution ratio of the water-based lubricant with water is usually 2 to 500 times.

[Water-based lubricant and coolant of the present invention]
The water-based lubricant of the present invention contains a lubricating component and a surfactant, and when diluted with water, based on the above formula (1) showing the relationship between the surface life t and the dynamic surface tension γ (t) The absolute value of the maximum dynamic surface tension decrease rate (V _max ) calculated by
The coolant of the present invention is obtained by diluting the water-based lubricant of the present invention with water, and contains water, a lubricating component, and a surfactant, and the relationship between the surface life t and the dynamic surface tension γ (t) The absolute value of the maximum dynamic surface tension decrease rate (V _max ) calculated based on the above formula (1) showing The dilution ratio with water is usually 2 to 500 times.

The water-based lubricant of one aspect of the present invention may be, for example, a type A1 emulsion-type water-based lubricant defined by JIS 2241:2000, or a type A2 soluble type lubricant defined by JIS 2241:2000. It may be a water-based lubricant or an A3 type solution-type water-based lubricant defined in JIS 2241:2000. Further, the coolant of one aspect of the present invention may be obtained by diluting these water-based lubricants with water.
The lubricating component and surfactant in the water-based lubricant and coolant of the present invention are as explained in the method for producing the water-based lubricant of the present invention. Moreover, the contents of the lubricating component and the surfactant are the same as the above-described blending amounts of the lubricating component and the surfactant.
The water-based lubricant and coolant of the present invention may contain additives that are commonly added to water-based lubricants and coolants within a range that does not impair the effects of the present invention.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.
In the following description, "room temperature" means 25°C.
Also, in the following description, "water" means ion-exchanged water.

[Various measurement and test methods]
The methods of dynamic surface tension measurement, static surface tension measurement, and antifoaming test carried out in this example are described below.

<Dynamic surface tension measurement>
Dynamic surface tension was measured by the maximum bubble pressure method using a Bubble Pressure dynamic surface tension meter BP100 (manufactured by KRUSS). Measurement conditions are shown below.
・Detection speed: 20mm/min
・Detection sensitivity: 50 Pa
・Start at surface age: 10ms
・Stop at surface age: 10ms
・Values: 10
・Immersion depth: 10.0mm
・Rising time: 30s
・Stirring speed: 400RPM
・Data Smoothing: Outlier Best 5 of 10 variables
The measurement operation procedure was as follows.
First, about 70 mL of the sample was put into the vessel. Then, the capillary was attached to the BP100 and the tip of the capillary was brought close to the liquid surface. Then, the above conditions were input and measurement was performed. Note that when the measurement is started, the capillary is inserted into the liquid according to the set value (immersion depth). Moreover, the measurement was implemented at room temperature.

<Static surface tension measurement>
In accordance with JIS K2241, a fully automatic surface tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) was used as a tester, and the measurement was performed at room temperature.

<Antifoaming test>
A defoaming test was carried out using a circulation-type Ross-Miles test apparatus shown in FIG.
Specifically, the column part A, the beaker part B that receives the sample dropped from the lower part of the column part A, and the beaker part B and the upper part of the column part A are connected via a liquid feeding means (gear pump). A circulating Ross-Miles test apparatus is used, in which a circulation path is formed from the beaker portion B to the upper portion of the column portion A by means of liquid feeding means through the pipes. Defoaming property was evaluated by foam height.
The test conditions and evaluation criteria were as follows.
(Test condition)
・Sample 1L: the same sample as the sample subjected to dynamic surface tension measurement, Ca: 10 mass ppm
・Gear pump: MG-2SP, 0.3MPa, 6L/min,
・Column part (A part): φ50 mm × 1200 mm
・Beaker part (B part): capacity 2L, height 235mm
・Piping: φ8mm, flow rate 5L/min
(Evaluation criteria)
The maximum foam height in the beaker part was evaluated for 60 minutes or until overflow occurred. In addition, it was set as the overflow when the beaker part exceeded 200 mm.

[Test sample]
Listed below are the compounds used to prepare the test samples.

<Amine>
・Monoethanolamine (MEA)
・Diethanolamine (DEA)
・Triethanolamine (TEA)
・Monoisopropanolamine (MIPA)
・Diisopropanolamine (DIPA)
・Triisopropanolamine (TIPA)
・N-methyldiethanolamine (Me-DEA)
・N-Cyclohexyldiethanolamine (Cy-DEA)
・Dicyclohexylamine (DCHA)
・N-methyldicyclohexylamine (Me-DCHA)
<Fatty acid>
・Hexanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, 3,5,5-trimethylhexanoic acid, neodecanoic acid, oleic acid

[Example 1]
Water with a fatty acid:amine molar ratio (fatty acid:amine) of 1:1.5 and a total concentration of fatty acid and amine adjusted to 10 mM was prepared as water containing a surfactant.
In Example 1, the amine was fixed to monoisopropanolamine (MIPA), and dynamic surface tension measurements and antifoaming tests were carried out on the following seven systems in which the type of fatty acid was changed for MIPA.
(1a) MIPA + hexanoic acid (1b) MIPA + nonanoic acid (1c) MIPA + decanoic acid (1d) MIPA + dodecanoic acid (1e) MIPA + 3,5,5-trimethylhexanoic acid (1f) MIPA + neodecanoic acid (1g) MIPA + oleic acid

The dynamic surface tension measurement results are shown in FIG. 4(A), and the defoaming test results (beaker portion foam height) with respect to the absolute value of the maximum dynamic surface tension decrease rate (V _max ) are shown in FIG. 4(B). .
First, among the above seven systems, the ones that did not cause overflow in the antifoaming test were (1a) MIPA + hexanoic acid, (1b) MIPA + nonanoic acid, and (1e) MIPA + 3,5,5-trimethylhexanoic acid. There were three systems.
From the results shown in FIG. 4(B), when the absolute value of the maximum dynamic surface tension decrease rate (V _max ) is less than 1, overflow does not occur, and the absolute value of the maximum dynamic surface tension decrease rate (V _max ) It was found that values greater than 1 caused overflow.
In addition, the maximum dynamic surface tension reduction rate (V The larger the absolute value _{of max} ), the higher the beaker foam height. It was found that a certain correlation was observed.
On the other hand, from the dynamic surface tension measurement result shown in FIG. 4(A) itself, the presence or absence of overflow and the above correlation could not be clearly confirmed.

[Example 2]
Experiments were carried out as in Example 1, except that the fatty acid was fixed to decanoic acid, and the following 8 types of systems in which the type of amine was changed for decanoic acid were used.
(2a) Decanoic acid + monoethanolamine (MEA)
(2b) Decanoic acid + diethanolamine (DEA)
(2c) Decanoic acid + triethanolamine (TEA)
(2d) Decanoic acid + monoisopropanolamine (MIPA)
(2e) Decanoic acid + diisopropanolamine (DIPA)
(2f) Decanoic acid + triisopropanolamine (TIPA)
(2 g) decanoic acid + N-methyldiethanolamine (Me-DEA)
(2h) Decanoic acid + N-cyclohexyldiethanolamine (Cy-DEA)

The dynamic surface tension measurement results are shown in FIG. 5(A), and the defoaming test results (beaker portion foam height) with respect to the absolute value of the maximum dynamic surface tension decrease rate (V _max ) are shown in FIG. 5(B). .
First, among the above eight systems, the ones that did not cause overflow in the defoaming test were (2a) decanoic acid + monoethanolamine (MEA) and (2g) decanoic acid + N-methyldiethanolamine (Me-DEA). There were two types of systems.
From the results shown in FIG. 5(B), when the absolute value of the maximum dynamic surface tension decrease rate (V _max ) is less than 1, overflow does not occur, and the absolute value of the maximum dynamic surface tension decrease rate (V _max ) It was found that values greater than 1 caused overflow.
In addition, the maximum dynamic surface tension reduction rate ( The larger the absolute value of V _max ), the higher the foam height in the beaker part _. It was found that there is a certain correlation between
On the other hand, from the dynamic surface tension measurement result itself shown in FIG. 5A, it was not possible to clearly confirm the presence or absence of overflow and the above correlation.

[Example 3]
The following 10 types of systems in which the fatty acid is fixed to oleic acid and the type of amine is changed for decanoic acid, and the total concentration of the fatty acid and the amine is adjusted to 0.2 mM. Example 1 was followed except that it was prepared as
(3a) oleic acid + monoethanolamine (MEA)
(3b) oleic acid + diethanolamine (DEA)
(3c) oleic acid + triethanolamine (TEA)
(3d) oleic acid + monoisopropanolamine (MIPA)
(3e) oleic acid + diisopropanolamine (DIPA)
(3f) oleic acid + triisopropanolamine (TIPA)
(3 g) oleic acid + N-methyldiethanolamine (Me-DEA)
(3h) oleic acid + N-cyclohexyldiethanolamine (Cy-DEA)
(3i) oleic acid + dicyclohexylamine (DCHA)
(3j) oleic acid + N-methyldicyclohexylamine (Me-DCHA)

The dynamic surface tension measurement results are shown in FIG. 6(A), and the defoaming test results (beaker portion foam height) with respect to the absolute value of the maximum dynamic surface tension decrease rate (V _max ) are shown in FIG. 6(B). .
First, among the above 10 systems, the two systems that did not cause overflow in the defoaming test were (3c) oleic acid + triethanolamine (TEA) and (3f) oleic acid + triisopropanolamine (TIPA). It was a species system.
From the results shown in FIG. 6(B), when the absolute value of the maximum dynamic surface tension decrease rate (V _max ) is less than 1, overflow does not occur, and the absolute value of the maximum dynamic surface tension decrease rate (V _max ) It was found that values greater than 1 caused overflow.
On the other hand, the occurrence of overflow could not be clearly confirmed from the dynamic surface tension measurement results shown in FIG. 6(A).

[Comparative Example 1]
FIG. 7 shows the results of plotting the antifoaming test results (beaker section foam height) against static surface tension for all the systems investigated in Examples 1 to 3 and the 20 mM aqueous solution of the above amine.
From the results shown in FIG. 7, it was clarified that although the lower the surface tension, the easier the overflow tends to occur, there are some systems that cannot be explained by this alone.
From this, the antifoaming property cannot be evaluated by static surface tension, and the validity of the antifoaming property evaluation method of the present invention, which uses the maximum dynamic surface tension decrease rate (V _max ) as an index, becomes clear. rice field.

Claims (7)

Using the results of measuring the dynamic surface tension of water containing a surfactant, the maximum dynamic surface tension decrease rate ( V _max ), and the maximum dynamic surface tension decrease rate (V _max ) is used as an index to evaluate the defoaming property of water containing the surfactant,
γ(t)= _γm +( _γ0 − _γm )/{1+(t/t ^* ) ⁿ } (1)
(In the above formula (1), _γ0 is the surface tension of water, _γm is the meso-equilibrium value of the surface tension, and t ^* is the time when γ(t) becomes intermediate between _γ0 and _γm . Yes, and n is a positive number.)
An antifoaming evaluation method, wherein the surfactant contains one or more fatty acid amine salts selected from (a) to (c) below.
(a) Fatty acid amine salt of one or more selected from fatty acids having 6 to 12 carbon atoms and one or more selected from primary amines having one alkanol group having 1 to 4 carbon atoms (b) carbon One or more selected from fatty acids having a number of 16 to 20 and a tertiary amine having three alkanol groups having 1 to 4 carbon atoms (the three alkanol groups may be the same or different, and the number of carbon atoms is 3 or more may have a linear structure or a branched structure.) fatty acid amine salt with one or more selected from (c) 1 selected from fatty acids having 16 to 20 carbon atoms and a tertiary amine having two alkanol groups having 1 to 4 carbon atoms and one hydrocarbon group having 1 to 8 carbon atoms (the two alkanol groups may be the same or different The alkanol group having 3 or more carbon atoms may have a linear or branched structure, and the hydrocarbon group having 1 to 8 carbon atoms may be a linear or branched aliphatic hydrocarbon group. or an alicyclic hydrocarbon group.) with one or more fatty acid amine salts The evaluation is based on the correlation obtained in advance between the maximum dynamic surface tension reduction rate (V _max ) of the water containing the surfactant and the defoaming performance measurement result of the water containing the surfactant. A method of evaluation according to claim 1, wherein the evaluation method is performed. A column section, a beaker section for receiving a sample dripped from the lower part of the column section, and a pipe connecting the beaker section and the upper part of the column section via a liquid feeding means, wherein the liquid feeding means By measuring the foam height of the sample in the beaker part using a circulation-type Ross-Miles test apparatus in which a circulation path is formed through a pipe from the beaker part to the upper part of the column part. The evaluation method according to claim 1 or 2, wherein the antifoaming property of water containing the surfactant is measured. The evaluation method according to any one of claims 1 to 3, wherein the dynamic surface tension of water containing the surfactant is measured by a maximum bubble pressure method. Any one of claims 1 to 4, wherein the defoaming property of water containing the surfactant is evaluated to be good when the absolute value of the maximum value (V _max ) of the dynamic surface tension reduction rate is less than 1. or the evaluation method described in 1. The evaluation method according to any one of claims 1 to 5, wherein the water containing the surfactant is a coolant obtained by diluting a water-based lubricant with water. For water containing a surfactant that is one or more fatty acid amine salts selected from the following (a) to (c), according to the antifoaming evaluation method according to any one of claims 1 to 6, A step of evaluating the defoaming properties of water containing the surfactant;
Based on this evaluation result, the maximum dynamic surface tension decrease calculated based on the following formula (1) showing the relationship between the surface life t and the dynamic surface tension γ(t) in water containing the surfactant determining surfactants exhibiting an absolute value of velocity (V _max ) less than 1; and
Using a new aliphatic amine salt surfactant having the same structure as the determined surfactant, mixing it with a lubricating component, diluting the resulting mixture with water 2 to 500 times, A method for producing a water-based lubricant , comprising the step of producing a water-based lubricant, wherein the absolute value of the maximum dynamic surface tension decrease rate (V _max ) is less than 1 ,
The above formula (1) is
γ(t)= _γm +( _γ0 − _γm )/{1+(t/t ^* ) ⁿ } (1)
(In the above formula (1), _γ0 is the surface tension of water, _γm is the meso-equilibrium value of the surface tension, and t ^* is the time when γ(t) becomes intermediate between _γ0 and _γm . Yes, and n is a positive number.)
and the above (a) to (c) defining the fatty acid amine salt are as follows .
(a) Fatty acid amine salt of one or more selected from fatty acids having 6 to 12 carbon atoms and one or more selected from primary amines having one alkanol group having 1 to 4 carbon atoms (b) carbon One or more selected from fatty acids having a number of 16 to 20 and a tertiary amine having three alkanol groups having 1 to 4 carbon atoms (the three alkanol groups may be the same or different, and the number of carbon atoms is 3 or more may have a linear structure or a branched structure.) fatty acid amine salt with one or more selected from (c) 1 selected from fatty acids having 16 to 20 carbon atoms and a tertiary amine having two alkanol groups having 1 to 4 carbon atoms and one hydrocarbon group having 1 to 8 carbon atoms (the two alkanol groups may be the same or different The alkanol group having 3 or more carbon atoms may have a linear or branched structure, and the hydrocarbon group having 1 to 8 carbon atoms may be a linear or branched aliphatic hydrocarbon group. or an alicyclic hydrocarbon group.) with one or more fatty acid amine salts

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