JP2016161464A - Method and system for extracting oxidation product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a system for extracting an oxidation product that can extract, from oil used in a machine or a facility, an oxidation product made of an oxidation inhibitor in the oil having been oxidized.SOLUTION: The method for extraction is for extracting an oxidation product from oil. Oil contains base oil as a polar solvent and an oxidation inhibitor as a polar solute. The oxidation product is generated through oxidation of the oxidation inhibitor. The method for extraction includes a mixing process and a filtering process. In the mixing process, oil and a non-polar solvent are mixed so that a mixed liquid containing the oil and the non-polar solvent is generated with the precipitated oxidation product. In the filtering process, the mixed liquid obtained in the mixing process is filtered through a filter.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an extraction method and an extraction system for an oxidation product generated by oxidation of an antioxidant contained in oil.

  Patent Document 1 has been proposed as a technique related to a method for determining oxidative deterioration of oil. Patent Document 1 discloses a simple determination method for oxidative degradation of oil. In the simple determination method, the oil applied to the mechanical system is subjected to membrane filter analysis twice. In the simple determination method, the results of the first measurement and the second measurement are compared, and the progress of oxidative degradation of the oil is determined. The second measurement is performed after a predetermined time from the first measurement. Patent Document 1 includes the RPVOT method and the RULER method as methods for examining the remaining ratio (residual amount) of the antioxidant of oil, and the following is described for each method. That is, in Patent Document 1, the RPVOT method is a method for evaluating the oxidation stability of a base oil or turbine oil of a lubricating oil, and is used for management of oil products, estimation of the remaining life of oil in use, and the like. It is described. In Patent Document 1, even if it is determined by the RULER method that a sufficient amount of antioxidant remains, there is a brown oil oxidation product in the machine or the oil is analyzed with a membrane filter. It is described that a brown substance which is an oxidation product of oil is often detected on the filter.

  Inventors etc. have proposed the oil state monitoring method and the oil state monitoring apparatus which monitor the state of deterioration of the oil used by the machine or equipment in patent document 2. FIG. In the oil condition monitoring method, oil is filtered by a filter. In the oil condition monitoring method, oil is filtered and oil is removed from a filter that captures contaminants present in the oil before filtration. In the oil state monitoring method, the color component of the transmitted light in which the light projected on the filter from which oil has been removed has passed through the filter is detected. Furthermore, in the oil state monitoring method, the color component of the reflected light reflected by the light projected on the filter from which oil has been removed is detected. The oil state monitoring device includes a light source and a color sensor. The light source captures contaminants and emits light that is projected onto the filter from which oil has been removed. The color sensor detects a color component of transmitted light in which light emitted from the light source is transmitted through the filter. Further, the color sensor detects the color component of the reflected light that is the light emitted from the light source reflected from the filter.

JP 2007-256213 A Japanese Patent No. 5190660

  The oil used in the machine or equipment is deteriorated depending on the use environment and / or the use time. Oil degradation can be broadly divided into two categories: oxidative degradation and fouling. Oxidative degradation is degradation due to oxidation, consumption or alteration of the base oil or additive. The fouling is deterioration due to contamination with water and / or wear powder.

  Regarding the oxidative degradation of oil, the progress of oxidation leads to a change in viscosity or generation of sludge, which causes early failure of machines and the like. Therefore, for example, an antioxidant is added to an oil that is used at a high temperature and requires oxidation stability. The oxidation of the base oil can be suppressed by the antioxidant. Antioxidants serve to interrupt the chain reaction of base oil auto-oxidation. As a result, the antioxidant is gradually consumed. For base oils with poor antioxidant properties, degradation proceeds rapidly if the antioxidant function is lost. Therefore, it is considered that knowing the degree of deterioration of the antioxidant is important in order to maintain the fluid characteristics required for the oil used in machines and the like.

  As a method for examining the remaining ratio (remaining amount) of the antioxidant, for example, there are various chromatographic methods, ASTM D2272, and ASTM D6810. Chromatographic methods can be analyzed in detail. However, this analysis requires specialized knowledge and equipment, and may take time and money. Therefore, the chromatographic method is not an on-site type diagnostic method. ASTM D2271 is the RPVOT (Rotating Pressure Vessel Oxidation Test) method described above. ASTM D2271 cannot measure the residual ratio of antioxidants. ASTM D6810 is the above-described RULER (Remaining Useful Life Evolution Routine) method. This measuring method has a problem that is pointed out in Patent Document 1.

  The inventor examined the diagnosis of the deterioration degree of the antioxidant. In this examination, the inventor paid attention to the relationship between the altered antioxidant substance captured by the filter by filtering the oil and the color of the filter after filtration. The altered product of the antioxidant is an oxidation product oxidized by the antioxidant. The inventor considered that it is important to extract an oxidation product oxidized by an antioxidant contained in the oil from the oil in order to obtain a favorable result by the above-described diagnosis.

  An object of the present invention is to provide an oxidation product extraction method and an extraction system capable of extracting an oxidation product oxidized by an antioxidant contained in the oil from oil used in machinery or equipment. And

  One aspect of the present invention is an extraction method for extracting an oxidation product produced by oxidation of an antioxidant from an oil containing a base oil that is a polar solvent and an antioxidant that is a polar solute. Mixing the oil and the nonpolar solvent to produce a mixed solution containing the oil and the nonpolar solvent, in which the oxidation product is deposited, and the mixed solution produced in the mixing step And a filtration step of filtering through a filter.

  According to this, the polarity of the whole liquid mixture can be reduced, and the oxidation product which is the modified substance of antioxidant which the antioxidant oxidized can be deposited. By filtering the liquid mixture in which the oxidation product is deposited, the oxidation product can be captured by a filter used for filtration. The filter that captured the oxidation product is set in the oil condition monitoring device of Patent Document 2 described above, and the deterioration condition of the antioxidant contained in the oil is diagnosed by executing the oil condition monitoring method of Patent Document 2. be able to. Color parameters that can be used for this diagnosis can be clarified.

  In the method for extracting an oxidation product, in the mixing step, the oil containing an amine-based antioxidant as the antioxidant and the nonpolar solvent may be mixed. According to this, Wurster salt precipitates as an oxidation product, and this can be captured by the filter. In this case, in the mixing step, the oil containing N-phenyl-1-naphthylamine which is an amine-based antioxidant as the antioxidant and the nonpolar solvent may be mixed. According to this, the oxidation product of N-phenyl-1-naphthylamine can be captured by the filter.

  In the method for extracting an oxidation product, in the mixing step, the oil and the nonpolar solvent having a dielectric constant of 1.92 or less may be mixed. According to this, the polarity of the whole liquid mixture can be reduced by the nonpolar solvent whose dielectric constant is 1.92 or less. The volume of the nonpolar solvent mixed with the oil can be reduced. In this case, in the mixing step, the oil and the nonpolar solvent petroleum ether, hexane, pentane, or heptane may be mixed. According to this, the polarity of the whole liquid mixture can be reduced by petroleum ether, hexane, pentane or heptane.

  In the method for extracting an oxidation product, in the mixing step, the mixing ratio of the oil and the petroleum ether that is the nonpolar solvent is set to a volume ratio of oil: petroleum ether = 1: 100 or less, and the oil and the petroleum ether are mixed. And may be mixed. According to this, the polarity of the whole liquid mixture can be reduced by petroleum ether. The volume of the nonpolar solvent mixed with the oil can be reduced. The color of the filter capturing the oxidation product can be set to a concentration suitable for diagnosis of the deterioration degree of the antioxidant.

  Another aspect of the present invention is an extraction system that extracts an oxidation product generated by oxidizing the antioxidant from an oil containing a base oil that is a polar solvent and an antioxidant that is a polar solute. An injection part for injecting a non-polar solvent to the oil; a storage part for storing a mixed liquid containing the oil and the non-polar solvent in which the oxidation product is deposited; and a filter, An extraction system comprising: a filtration unit that filters the mixed liquid stored in the storage unit through the filter.

  According to this, the oxidation product extraction method described above is executed, and the oxidation product oxidized by the antioxidant can be captured by the filter as described above. As above, the degree of deterioration of the antioxidant contained in the oil can be diagnosed. Color parameters that can be used for this diagnosis can be clarified. Regarding the operation of injecting a non-polar solvent into the oil performed by the injection unit of the extraction system, this operation by the injecting unit includes the operation of injecting a non-polar solvent into the oil and the operation of injecting oil into the non-polar solvent including.

  ADVANTAGE OF THE INVENTION According to this invention, the oxidation product extraction method and extraction system which can extract the oxidation product which the antioxidant contained in this oil oxidized from the oil used with the machine or the installation are obtained. it can.

It is a figure which shows the outline of the mixing process of an extraction method. It is the plane enlarged photograph and cross-sectional enlarged photograph of a membrane filter. It is a figure which shows schematic structure of a filtration apparatus. It is a figure which shows the principle of the measurement of a color. It is a photograph which shows an example of a hue discrimination device. It is an experimental result regarding the relationship between the color of multiple types of nonpolar solvents and membrane patches. It is an experimental result regarding the relationship between the capacity of petroleum ether and the color of the membrane patch. The present invention relates to an experiment using a mixed liquid in which the volume of sample oil is constant and the volume of petroleum ether is changed. It is a graph which shows the RGB value of the membrane patch shown in FIG. It relates to a sample oil with a reduced pressure of 1 PSI. It is a graph which shows the RGB value of the membrane patch shown in FIG. It relates to a sample oil with a reduced pressure of 3 PSI. It is a graph which shows the RGB value of the membrane patch shown in FIG. It relates to a sample oil with a reduced pressure of 5 PSI. It is a graph which shows (DELTA) E _RGB calculated | required from each RGB value of FIGS. 8-10 based on the experimental result of FIG. It is an experimental result regarding the relationship between the capacity of petroleum ether and the color of the membrane patch. The present invention relates to an experiment using a mixed liquid in which the volume of sample oil is changed and the mixing ratio of petroleum ether to sample oil is constant. It is a graph which shows the RGB value of the membrane patch shown in FIG. It relates to a sample oil with a reduced pressure of 1 PSI. It is a graph which shows the RGB value of the membrane patch shown in FIG. It relates to a sample oil with a reduced pressure of 3 PSI. It is a graph which shows the RGB value of the membrane patch shown in FIG. It relates to a sample oil with a reduced pressure of 5 PSI. 16 is a graph showing ΔE _RGB obtained from each RGB value of FIGS. 13 to 15 based on the experimental result of FIG. 12. It is the experimental result regarding the color of several kinds of liquid mixture and membrane patch which changed the mixing ratio of sample oil and petroleum ether. It relates to experiments with mixed liquids where the mixing ratio of sample oil and petroleum ether is inappropriate. It is an experimental result regarding the relationship between the drop pressure amount of sample oil and the color of the membrane patch. It is a graph which shows the RGB value of the membrane patch shown in FIG. It is a graph which shows (DELTA) E _RGB calculated | required from each RGB value of FIG. 19 based on the experimental result of FIG. It is a total ion chromatogram of a new oil and the sample oil of 9 PSI of drop pressures. It is an analysis result which shows the change of the residual amount of an amine antioxidant. It is a graph which shows the relationship between (DELTA) E _RGB and the residual rate of antioxidant.

  Embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the configurations described below, and various configurations can be employed in the same technical idea. For example, some of the configurations shown below may be omitted or replaced with other configurations. Other configurations may be included.

<Oxidation product extraction method>
The method for extracting the oxidation product will be described with reference to FIGS. In the embodiment, the extraction method of the oxidation product is simply referred to as “extraction method”. The extraction method is performed on oil used in machinery or equipment. The oil contains base oil and additives such as antioxidants. In an embodiment, the oil shall contain an antioxidant as an additive. Examples of the oil containing the antioxidant include lubricating oil. The oil in the embodiment includes turbine oil and various industrial oils (lubricating oils) such as hydraulic oil. Furthermore, the oil in the embodiment includes a synthetic oil. In the embodiment, as is apparent from the above description, the solution containing the base oil and the antioxidant is referred to as “oil” or “lubricating oil”, and the oil as the solvent is referred to as “base oil”.

  Base oil is a polar solvent. Antioxidants are polar solutes. Examples of the base oil include ester-based synthetic oils. Antioxidants are additives for suppressing oxidative degradation of organic compounds. Examples of the antioxidant include phenolic, amine-based, phosphorus-based and sulfur-based agents. For example, it is assumed that an amine-based antioxidant is added as the antioxidant. In this case, the oil is an oil in which an amine-based antioxidant is dissolved in an ester-based synthetic oil as a base oil. For example, in turbine oil, the environment in which turbine oil is used has become high temperature, and high oxidation stability is required. Amine-based antioxidants have been attracting attention in recent years because they can achieve high oxidation stability even at high temperatures. An example of the amine-based antioxidant is N-phenyl-1-naphthylamine. In addition, examples of amine-based antioxidants include 4,4-dioctyldiphenylamine. In an embodiment, N-phenyl-1-naphthylamine is referred to as “PANA”. 4,4-Dioctyldiphenylamine is referred to as “DODPA”.

  The extraction method includes a mixing step and a filtration step. In the mixing step, as shown in FIG. 1, the oil and the nonpolar solvent are mixed, and a mixed liquid containing the oil and the nonpolar solvent is generated. In the mixed solution produced in the mixing step, an oxidation product (salt) oxidized by the antioxidant is deposited. That is, in the mixing step, by mixing the oil and the nonpolar solvent, a mixed liquid containing the oil and the nonpolar solvent in which the oxidation product is precipitated is generated. In the lower part of FIG. 1, black circles illustrated in the mixed solution indicate oxidation products. The precipitation of the oxidation product is caused by the fact that the base oil, which is a polar solvent, is diluted with a nonpolar solvent, and the polarity of the whole mixed solution is lowered. A solute having polarity does not dissolve in a solvent with reduced polarity or a nonpolar solvent. When the antioxidant is an amine-based antioxidant, the salt precipitated in the mixing step is a Wurster salt. In an embodiment, a nonpolar solvent is a solvent that can precipitate an oxidation product in a mixture when mixed with oil. Examples of the nonpolar solvent include petroleum ether. Petroleum ether has a dielectric constant of 1.84 and a dipole moment of 0D (debye). Other nonpolar solvents will be described later.

  In the filtration step, the mixed solution generated in the mixing step is filtered. In the filtration step, for example, a membrane filter 11 is used as a filter. As the membrane filter 11, for example, a membrane filter having a pore diameter of 0.8 μm and a thickness of 0.125 mm is used (see FIG. 2). The thickness of the membrane filter 11 is the dimension of the membrane filter 11 in the filtration direction. The membrane filter 11 is a known filter. Therefore, the other description regarding the structure etc. of the membrane filter 11 is abbreviate | omitted.

  In the filtration step, the mixed solution is filtered through the membrane filter 11. The membrane filter 11 captures the oxidation product oxidized by the antioxidant. That is, based on the above-described example, the membrane filter 11 captures the Wurster salt. The Wurster salt is a kind of amine and therefore exhibits various colors from red to blue. Therefore, the membrane filter 11 that has captured the Wurster salt is colored.

<Extraction system>
The extraction method is executed by an extraction system. That is, the extraction system extracts an oxidation product generated by oxidation of an antioxidant from an oil containing a base oil that is a polar solvent and an antioxidant that is a polar solute. The extraction system includes an injection unit, a storage unit, and a filtration unit. The injection unit injects a nonpolar solvent into the oil. The injection part has a function as a dropper. For example, the injection unit stores a nonpolar solvent and injects the nonpolar solvent into oil stored in a predetermined container. The operation of injecting the nonpolar solvent into the oil performed by the injection unit may be performed by injecting oil into the nonpolar solvent stored in a predetermined container.

  The oil and the nonpolar solvent are mixed (mixing step). A storage part stores the liquid mixture of oil and a nonpolar solvent in which the oxidation product deposited. The filtration unit includes a membrane filter 11. In the filtration part, the liquid mixture stored in the storage part is filtered through the membrane filter 11 (filtration process). A storage part and a filtration part respond | correspond to the filtration apparatus 20 mentioned later based on FIG. That is, the storage unit has a configuration corresponding to the cylinder 22 in the filtration device 20. The filtration unit has a configuration corresponding to the membrane filter 11 and the flask 23 in the filtration device 20. The filtration unit may include a configuration corresponding to the vacuum pump 24 in the filtration device 20.

<Example>
An extraction method was established and experiments were conducted to confirm its effectiveness. Hereinafter, this experiment will be described.

<Experiment method>
The sample oil and filtration device 20 used in this experiment will be described. Furthermore, an outline of the oil state determination will be described.

<Sample oil>
The sample oil is an oxidized oil obtained by oxidizing an ester-based synthetic oil (brand: Mobil Jet oil II) to which an amine-based antioxidant is added using the RPVOT method. The above-mentioned ester synthetic oil (brand: Mobil Jet oil II) is used for, for example, a jet engine or a combined cycle generator. The sample oil contains PANA and DODPA as amine-based antioxidants. This point will be described later. In the experiment, a sample oil that was oxidized stepwise was produced by arbitrarily changing the amount of pressure drop of oxygen present with the oil to oxidize the oil. That is, as the sample oil, a plurality of oxidized oils having different degrees of oxidation due to the difference in oxygen pressure drop were prepared. The amount of reduced pressure of oxygen was one of five types of 1, 3, 5, 7 and 9 PSI (pound-force per square inch). A sample oil having a reduced pressure amount of 0 PSI corresponds to a new oil. 1 PSI is 6894.76 Pa.

An RPVOT tester was used to prepare the sample oil. During the production, distilled water was added to the ester-based synthetic oil which is a new oil. A sample beaker storing an ester-based synthetic oil to which distilled water was added was placed in a pressure chamber of an RPVOT tester, and rotated at a predetermined speed while being heated at a predetermined temperature. At that time, distilled water was also put into the pressure chamber. The addition of new oil and distilled water to the pressure chamber takes into consideration that water may be mixed into the oil and deteriorate the oil in actual use. The experimental conditions of the RPVOT method are as follows.
<Experimental conditions of RPVOT method>
Lubricating oil amount (g): 50 ± 0.5
Distilled water volume (g): 5 (sample beaker)
5 (pressure chamber)
Temperature (° C): 150
Rotational speed (rpm): 100 ± 5
The RPVOT tester is a known device. Therefore, the description regarding this is abbreviate | omitted. However, the copper coil used as a catalyst was not used in the RPVOT tester used in the experiment. This is to prevent the copper oxide deposited by the copper coil used as the catalyst from affecting the color of the membrane filter 11 that has captured the Wurster salt.

<Filtration device>
As shown in FIG. 3, the filtration device 20 includes a dust-proof lid 21, a cylinder 22, a flask 23, and a vacuum pump 24. The membrane filter 11 is attached between the cylinder 22 and the flask 23. In the experiment, as the membrane filter 11, a membrane filter made of cellulose acetate (manufactured by Advantech Toyo Co., Ltd., product name: C080A025A) was used. Regarding the specification of the membrane filter 11, the pore diameter is 0.8 μm and the thickness is 0.125 mm. Filtration of a mixture of sample oil and various nonpolar solvents described below was performed by storing the mixture in a cylinder 22 and reducing the pressure inside the flask 23 using a vacuum pump 24. In FIG. 3, the halftone dot pattern shown in the filtration device 20 indicates a mixed solution. That is, the halftone dot pattern above the membrane filter 11 in FIG. 3 indicates the mixed solution before filtration. The halftone dot pattern below the membrane filter 11 indicates the mixed solution after filtration. In the experiment, a region R (see FIG. 4) in which the mixed liquid is filtered in the membrane filter 11 has a diameter of about 18 mm (area: about 992 mm ² ).

  After the filtration was completed, the membrane filter 11 was removed from the filtration device 20. The oil was removed from the membrane filter 11 removed from the filtration device 20. Petroleum ether was used for oil removal. Thereafter, the membrane filter 11 was dried.

<Oil condition judgment>
In order to determine the state of the sample oil, the color of the membrane filter 11 was quantitatively measured. The area of the membrane filter 11 to be measured for color is the colored area R that captures the Wurster salt. In the embodiment, the membrane filter 11 to be determined is referred to as a “membrane patch 12”. The color of the membrane patch 12 was measured by the method proposed by the inventors in Patent Document 2. In this method, for example, white light is projected onto the membrane patch 12 from both the front and back sides of the membrane patch 12, and the reflected light and transmitted light of the projected white light are measured by the color sensor 30 (see FIG. 4). ). As the color sensor 30, for example, a hue discrimination device (CPA Colorimetric patch Analyzer) developed by the inventors as shown in FIG. 5 can be adopted. In this experiment, this apparatus was used as the color sensor 30. However, a known color sensor that outputs the RGB value of the measurement light can also be adopted as the color sensor 30. The color sensor 30 is provided to face the front surface and / or back surface of the membrane patch 12. The surface of the membrane patch 12 is a surface on the side of the cylinder 22 in a state where the membrane filter 11 is set in the filtration device 20 (see FIG. 3). The back surface of the membrane patch 12 is the surface on the flask 23 side in the state described above.

In the above-described method, for example, the color (RGB value) of the contaminant captured on the surface of the membrane patch 12 can be clarified by the reflected light reflected on the surface of the membrane patch 12. The color (RGB value) of contaminants captured on the surface and inside of the membrane patch 12 can be clarified by the transmitted light transmitted from the back side to the front side of the membrane patch 12. From the RGB values of the reflected light and transmitted light measured by the color sensor 30, ΔE _RGB is calculated based on the following equation (1). ΔE _RGB indicates the distance between white (R255, G255, B255) and the measured RGB value. By using the extraction method and the technique of Patent Document 2, the degree of deterioration of the antioxidant contained in the oil can be determined easily and quickly. Cost can also be reduced. At this time, ΔE _RGB is a distance from white (R255, G255, B255). However, ΔE _RGB can also be defined as a distance from black (R0, G0, B0) as in Patent Document 2. By determining the maximum color difference of RGB values, it is possible to roughly specify the cause of oil degradation. For the maximum color difference, for example, the RGB value is (R170, G114, B49). The maximum color difference at this time is 121 (R170-B49). In addition, it is assumed that the RGB value is (R150, G149, B133). The maximum color difference at this time is 17 (R150-B133). The deterioration factor when the maximum color difference is 121 is oxidation, and the deterioration factor when the maximum color difference is 17 is fouling. Details of the technique proposed by the inventors are disclosed in Patent Document 2. Therefore, the other description regarding this is abbreviate | omitted.

In this experiment, the white light was projected from the back side of the membrane patch 12, and the transmitted light transmitted through the white light to the front side of the membrane patch 12 was measured by the color sensor 30. Therefore, the RGB values described in the experimental results described below are the R value, the G value, and the B value of the transmitted light, and ΔE _RGB is a value obtained from such RGB values by the above formula (1). It is. The measurement target of the color sensor 30 may be, for example, white light projection from the surface side of the membrane patch 12 and reflected light reflected from the surface of the membrane patch 12. In addition, white light is projected from the front side of the membrane patch 12, and transmitted light transmitted to the back side of the membrane patch 12 or white light is projected from the back side of the membrane patch 12. You may make it measure the reflected light reflected on the back surface of the patch 12. Furthermore, two or more of each of the transmitted light and the reflected light described above may be measured. 6, 7, 12, 17, and 18, the appearance of the membrane patch (reference numeral “12” is omitted) is the surface of the membrane filter 11.

<Experimental results and discussion>
<Relationship between nonpolar solvent and membrane patch color>
Regarding the nonpolar solvent mixed with the oil in the extraction method, the relationship between the colors of the plural types of nonpolar solvents and the membrane patch will be described with reference to FIG. This reveals preferred nonpolar solvents in the extraction process. The mixed solution 1 to the mixed solution 4 shown in FIG. 6 are solutions obtained by mixing a fixed volume of sample oil and a fixed volume of nonpolar solvents of different types. The details are as follows.
<Mixed liquid>
Mixture 1: 0.1 ml of sample oil + 20 ml of petroleum ether
Mixture 2: Sample oil 0.1 ml + hexane 20 ml
Mixture 3: sample oil 0.1 ml + toluene 20 ml
Mixture 4: Sample oil 0.1 ml + diethyl ether 20 ml
Regarding mixed liquid 1 to mixed liquid 4, the sample oil to be mixed with various nonpolar solvents was an oxidized oil having a reduced pressure of 9 PSI prepared by the RPVOT method. The polarities of the various nonpolar solvents in the mixed liquid 1 to the mixed liquid 4 are the lowest in petroleum ether, the higher in the order of hexane and toluene, and the highest in diethyl ether. The main component of petroleum ether is pentane. Petroleum ether is a mixture of pentane and hexane. The dielectric constants and dipole moments of various nonpolar solvents in the mixed liquid 1 to the mixed liquid 4 are as follows. As reference values, the dielectric constant and dipole moment of pentane and heptane (both nonpolar solvents) and the dielectric constant and dipole moment of acetone, ethanol and water (both polar solvents) are also shown.
<Polarity>
Petroleum ether (mixed liquid 1): Dielectric constant 1.84 Dipole moment 0D
Hexane (mixed liquid 2): Dielectric constant 1.89 Dipole moment 0D
Toluene (mixed solution 3): Dielectric constant 2.38 Dipole moment 1.20D
Diethyl ether (mixture 4): Dielectric constant 4.30 Dipole moment 3.83D
Pentane: Dielectric constant 1.84 Dipole moment 0D
Heptane: Dielectric constant 1.92 Dipole moment 0D
Acetone: Dielectric constant 21.0 Dipole moment 9.67D
Ethanol: Dielectric constant 25.3 Dipole moment 5.64D
Water: Dielectric constant 78.5 Dipole moment 6.74D
As is clear from FIG. 6, the membrane patch using petroleum ether having a low polarity (see “mixed liquid 1”) and hexane (see “mixed liquid 2”) as the nonpolar solvent becomes black purple, and ΔE _RGB is large. The value is shown. On the other hand, membrane patches using toluene (see “mixture 3”) and diethyl ether (see “mixture 4”), which are more polar than petroleum ether and hexane, show almost no coloration and ΔE _RGB also has a small value. Indicated.

  In the sample oil, an ester-based synthetic oil is used as the base oil. In the ester-based synthetic oil, the ester has polarity. Therefore, it is considered that the Wurster salt was dissolved in the sample oil in the form of ions. Among the nonpolar solvents used in the experiment, especially a low polarity solvent such as petroleum ether or hexane can reduce the polarity of the whole mixed solution by mixing 20 ml with 0.1 ml of sample oil. it can. Along with this, the Wurster salt dissolved in the sample oil is precipitated, and the membrane patch is considered to be colored. On the other hand, it is considered that toluene or diethyl ether could not sufficiently reduce the polarity of the whole liquid mixture in an amount of 20 ml with respect to 0.1 ml of sample oil. Therefore, it is considered that the Wurster salt did not precipitate.

<Mixing ratio>
Regarding the volume of the nonpolar solvent mixed with the oil in the extraction method, the relationship between the volume of the sample oil and the volume of the nonpolar solvent will be described with reference to FIGS. This reveals a suitable mixing ratio in the extraction method. The sample oil was produced by the RPVOT method. The solvent to be mixed with the sample oil was petroleum ether (see “mixed liquid 1” shown in FIG. 6), which is a nonpolar solvent, based on the experimental results described above with reference to FIG.

(1) Experiments using a mixed liquid in which the volume of the sample oil was constant and the volume of the petroleum ether was changed The sample oil was each oxidized oil having a reduced pressure of 1, 3, 5 PSI. The volume of each sample oil with a decreasing pressure of 1, 3, 5 PSI was constant at 0.1 ml. The membrane patch obtained by filtering each liquid mixture obtained by mixing 0.1 ml of each sample oil having a reduced pressure of 1, 3, 5 PSI and 10, 20, 40, 60 ml of petroleum ether was in a state as shown in FIG. The experiment was omitted with respect to a mixed solution obtained by mixing 0.1 ml of sample oil having a pressure of 1 PSI and 60 ml of petroleum ether. For the sample oil with a drop pressure of 1 PSI, the RGB value and ΔE _RGB are substantially constant as the petroleum ether capacity increases (see FIGS. 8 and 11).

In the membrane patch obtained by filtering each liquid mixture obtained by mixing 0.1 ml of the sample oil having a lower pressure of 1 PSI and 10, 20, 40 ml of petroleum ether, the RGB values are as shown in FIG. In the membrane patch obtained by filtering each liquid mixture obtained by mixing 0.1 ml of the sample oil having a lower pressure of 3 PSI and 10, 20, 40, and 60 ml of petroleum ether, the RGB values are as shown in FIG. In the membrane patch obtained by filtering each liquid mixture obtained by mixing 0.1 ml of the sample oil having a lower pressure of 5 PSI and 10, 20, 40, 60 ml of petroleum ether, the RGB values are as shown in FIG. ΔE _RGB obtained from each RGB value shown in FIGS. 8 to 10 is as shown in FIG.

For each sample oil with a different amount of pressure drop, even when the petroleum ether volume was changed, there was almost no change in the color of the membrane patch (see “Color of Region R” shown in FIG. 4) and the RGB value. (See FIGS. 7 to 10). As a result, in each sample oil having a different pressure drop, even when the petroleum ether capacity changed, ΔE _RGB hardly changed (see FIG. 11).

(2) Experiment with a mixed liquid in which the volume of the sample oil was changed and the mixing ratio of petroleum ether to the sample oil was constant. The sample oil was each oxidized oil having a drop pressure of 1, 3, 5 PSI. The volume of each sample oil with a drop pressure of 1, 3, 5 PSI was 0.1, 0.2, 0.3, 0.4, 0.5 ml. The mixing ratio of petroleum ether to sample oil was constant at a volume ratio of sample oil: petroleum ether = 1: 100. That is, when the sample oil was 0.1 ml, the volume of petroleum ether was 10 ml. When the sample oil was 0.2 ml, the volume of petroleum ether was 20 ml. When the sample oil was 0.3 ml, the volume of petroleum ether was 30 ml. When the sample oil was 0.4 ml, the petroleum ether volume was 40 ml. When the sample oil was 0.5 ml, the volume of petroleum ether was 50 ml.

  Each sample oil 0.1, 0.2, 0.3, 0.4, 0.5 ml with a drop pressure of 1, 3, 5 PSI and the mixing ratio of sample oil and petroleum ether in volume ratio, sample oil: petroleum The membrane patch obtained by filtering each liquid mixture in which petroleum ether was mixed with ether = 1: 100 was in a state as shown in FIG.

Sample oil 0.1, 0.2, 0.3, 0.4, 0.5 ml with a drop pressure of 1 PSI and the mixing ratio of sample oil and petroleum ether in volume ratio, sample oil: petroleum ether = 1: 100 In the membrane patch obtained by filtering each liquid mixture in which petroleum ether was mixed, the RGB values were as shown in FIG. In the membrane patch obtained by filtering each of the mixture liquids of 0.1, 0.2, 0.3, 0.4, and 0.5 ml of the sample oil having a drop pressure of 3 PSI and the above-described mixing ratio of petroleum ether, the RGB value is As shown in FIG. In the membrane patch obtained by filtering each of the mixture liquids of 0.1, 0.2, 0.3, 0.4, and 0.5 ml of the sample oil having a decreasing pressure of 5 PSI and the above-described mixing ratio with petroleum ether, the RGB value is As shown in FIG. ΔE _RGB obtained from each RGB value described above is as shown in FIG.

In the sample oil with a lower pressure of 1 PSI, when the volume of the sample oil increases, the color of the membrane patch (see “Color of region R” shown in FIG. 4) darkens and the RGB value also increases (see FIGS. 12 and 13). ). As a result, in the sample oil with a lower pressure of 1 PSI, ΔE _RGB increased as the volume of the sample oil increased (see FIG. 16). For each sample oil with a drop pressure of 3 and 5 PSI, if the volume is 20 ml or more, the color of the membrane patch (see “Color of region R” shown in FIG. 4) and the RGB value are changed even if the volume of the sample oil changes. There was little change (see FIGS. 12, 14 and 15). As a result, in each sample oil with a drop pressure of 3,5 PSI, even if the volume of the sample oil changed, ΔE _RGB hardly changed (see FIG. 16).

(3) From the results of the two experiments regarding the mixing ratio described above, if the mixing ratio of sample oil and petroleum ether is sufficient and constant, the amount of precipitates does not depend on the volume of petroleum ether, and the volume of sample oil It became clear to decide only by. By setting the mixing ratio of sample oil and petroleum ether to volume ratio, sample oil: petroleum ether = 1: 100, ΔE _RGB can be clarified. At that time, even if the volume of the sample oil is 0.1 ml, ΔE _RGB that can be used for diagnosis of the degree of deterioration of the antioxidant contained in the oil can be obtained.

When the mixing ratio of the sample oil and petroleum ether is not appropriate, the membrane patch obtained by filtering the mixed liquid having the inappropriate mixing ratio is in a state as shown in FIG. In FIG. 17, each liquid mixture with a mixing ratio of 1 to 4 is as follows. At a mixing ratio of 1, the volume of the filtered liquid mixture is 15 ml.
<Mixed liquid>
Mixing ratio 1: 25 ml of sample oil + 50 ml of petroleum ether (sample oil: petroleum ether = 1: 2)
Mixing ratio 2: sample oil 1 ml + petroleum ether 10 ml (sample oil: petroleum ether = 1: 10)
Mixing ratio 3: sample oil 1 ml + petroleum ether 15 ml (sample oil: petroleum ether = 1: 15)
Mixing ratio 4: 1 ml of sample oil + 20 ml of petroleum ether (sample oil: petroleum ether = 1: 20)
The cause of the membrane patch being in the state shown in FIG. 17 is considered as follows. That is, when the mixing ratio is 1 to 4, the volume of petroleum ether relative to the sample oil is small, and the polarity of the sample oil cannot be sufficiently reduced by the petroleum ether. As a result, sufficient Wurster salt is not precipitated.

<Relationship between sample oil drop pressure and membrane patch color>
The relationship between the drop pressure amount of the sample oil and the color of the membrane patch will be described with reference to FIGS. This confirms that the color of the membrane patch has a correlation with the amount of pressure drop.

  Sample oil was made into each oxidation oil of the drop pressure 1,3,5,7,9PSI produced by RPVOT method. The solvent to be mixed with the sample oil was petroleum ether (see “mixed liquid 1” shown in FIG. 6), which is a nonpolar solvent, based on the experimental results described above with reference to FIG. The mixing ratio (volume ratio) of sample oil and petroleum ether and their respective capacities are determined from the experimental results described above with reference to FIGS. 7 to 16, and sample oil: petroleum ether = 1: 100, sample oil 0.1 ml 10 ml.

  The membrane patch obtained by filtering each liquid mixture obtained by mixing 0.1 ml of each sample oil having a decreasing pressure of 1, 3, 5, 7, 9 PSI and 10 ml of petroleum ether was in a state as shown in FIG.

In the membrane patch obtained by filtering each liquid mixture obtained by mixing 0.1 ml of each sample oil having a decreasing pressure of 1, 3, 5, 7, 9 PSI and 10 ml of petroleum ether, the RGB values are as shown in FIG. ΔE _RGB obtained from each RGB value shown in FIG. 19 is as shown in FIG.

The color of the membrane patch (see “color of region R” shown in FIG. 4) becomes darker as the amount of pressure drop increases. Therefore, ΔE _RGB also increases monotonously. That is, as the degree of deterioration of the antioxidant contained in the oil progresses, ΔE _RGB shows a large value.

<Qualitative and quantitative analysis by gas chromatograph mass spectrometry>
The results of qualitative and quantitative analysis by gas chromatograph mass spectrometry (GC / MS) will be described with reference to FIG. 21 and FIG. Thus, as described above, it is confirmed that the color of the membrane patch having a correlation with the decreasing pressure amount has a correlation with the deterioration degree of the antioxidant and can be used for diagnosis of the deterioration degree of the antioxidant. .

  This analysis was performed on the following sample oil. That is, the sample oil was a fresh oil (reducing pressure 0 PSI) and oxidized oils having reduced pressures 1, 5, and 9 PSI produced by the RPVOT method.

  In the total ion chromatogram of the sample oil with the new oil shown in the upper part of FIG. 21, the oil (brand: Mobil Jet oil II) used as the sample oil contains PANA and DODPA, which are amine antioxidants. It was recognized that In the total ion chromatogram of the sample oil having a reduced pressure of 9 PSI shown in the lower part of FIG. 21, hydrolysis products were observed. When heated in the presence of water, the polyol ester of the base oil of the sample oil is hydrolyzed to acid and alcohol. The hydrolysis products are carboxylic acids such as 2-methylbutyric acid, valeric acid, enanthic acid, caprylic acid and capric acid. In addition, ester compounds, 1,4-naphthoquinone, aniline and tricresyl phosphates were produced.

  The residual amounts of PANA and DODPA contained in each sample oil of the new oil and the decreasing pressure of 1,5,9 PSI were as shown in FIG. According to this result, it is recognized that the residual amount of the amine-based antioxidant is reduced with an increase in the pressure drop. In particular, in PANA, as compared with DODPA, the decrease in the residual amount accompanying the increase in the pressure drop was remarkable.

<Summary>
The inventors clarified that there is a certain relationship between the color of the membrane patch 12 after filtering the oil and the deterioration of the lubricating oil, and proposed an oil condition monitoring method and the like in Patent Document 2 described above. Yes. For example, in a turbine oil in which an amine-based antioxidant is added to an ester-based synthetic oil, the oxidation quality of the amine (oxidation product) affects the color of the patch, making it difficult to measure conventional lubricants. I found out that In recent years, amine-based antioxidants having excellent heat-resistant oxidation stability have been added to turbine oils that are used in high-temperature and / or harsh environments. Therefore, it is very important to elucidate the influence of the oxidation product of the amine antioxidant on the color of the membrane patch 12.

  From the results of the above-mentioned experiment conducted in consideration of such points, the following has become clear. This suggests the possibility of diagnosing degradation of amine antioxidants using the color of the membrane patch 12.

  (1) The Wurster salt is dissolved as an ion in an ester synthetic oil. Wurster salt precipitates when the polarity of the oil is reduced by petroleum ether. The Wurster salt can be captured by the membrane filter 11 by filtering the mixed solution in which the Wurster salt is deposited. In the membrane patch 12, the region R in which the Wurster salt is captured becomes purple.

  (2) The mixing ratio of the sample oil and petroleum ether that can be used for diagnosis of the deterioration degree of the amine-based antioxidant is a volume ratio of sample oil: petroleum ether = 1: 100. With such a mixing ratio, the color of the membrane filter 11 that has captured the oxidation product can be set to a concentration suitable for the diagnosis of the degree of deterioration of the antioxidant by the technique of Patent Document 2.

(3) There is a certain relationship between the alteration product (oxidation product) due to oxidation of the amine-based antioxidant and the color parameter (ΔE _RGB ) of the membrane patch 12 as shown in FIG. ΔE _RGB increases especially as PANA decreases. Regarding the change in ΔE _RGB, the influence of the oxidation product of PANA is dominant. It is considered that the region R that captured PANA appears as purple in the membrane patch 12.

<Modification>
The embodiment can also be performed as follows. Some configurations of the modifications shown below can be appropriately combined and employed. Hereinafter, points different from the above will be described, and description of similar points will be omitted as appropriate.

(1) In the above, as a preferable mixing ratio of oil (sample oil) and petroleum ether, the volume ratio was oil: petroleum ether = 1: 100. As described above, ΔE _RGB hardly changes even when the petroleum ether capacity changes in the sample oils having different drop pressure amounts. Therefore, the mixing ratio described above may be smaller than the sample oil: petroleum ether = 1: 100 in volume ratio. That is, the mixing ratio of oil and petroleum ether may be a volume ratio of oil: petroleum ether = 1: 100 or less.

(2) In the above, the mixing ratio of oil (sample oil) and petroleum ether is a volume ratio of oil: petroleum ether = 1: 100, the oil volume is 0.1 ml, and the petroleum ether volume is 10 ml. . The volume of oil and the volume of petroleum ether may be appropriately changed within the range where the mixing ratio is the value described above. When the volume of oil and the volume of petroleum ether, in other words, the volume of the mixed liquid, is an amount corresponding to the area of the membrane filter 11 region (see “region R” shown in FIG. 4) that captures the Wurster salt. Good. For example, when the volume of the mixed liquid is increased from 10.1 ml, the above-described region in the membrane filter 11 may be widened according to the increase amount of the mixed liquid. On the other hand, when the volume of the mixed liquid is less than 10.1 ml, the above-described region in the membrane filter 11 may be narrowed according to the amount of decrease in the mixed liquid. In the experiment in the embodiment, in the membrane filter 11, the aforementioned region has a diameter of about 18 mm (area: about 992 mm ² ) as described above.

  (3) Although description is omitted above, heptane may be used as the nonpolar solvent. In addition, you may make it use the pentane which is a main component of petroleum ether. The dielectric constant and dipole moment of heptane and pentane are as described above. Similar results as petroleum ether can be obtained with heptane or pentane. About the dipole moment in a nonpolar solvent, the value should just be a very small predetermined value besides the case where it is 0D.

(4) In the above description, ΔE _RGB is described as an example of the color parameter according to Patent Document 2. The color parameter for diagnosing the degree of deterioration of the antioxidant may be a color difference based on a different color system. For example, the color difference ΔE ^* ab based on the L ^* a ^* b ^* color system (CIE 1976) may be employed. The color sensor 30 is a color sensor corresponding to the color system employed.

11 Membrane filter, 12 Membrane patch, 20 Filtration device, 21 Dust-proof lid, 22 Cylinder, 23 Flask, 24 Vacuum pump, 30 Color sensor, R region

Claims (7)

An extraction method for extracting an oxidation product produced by oxidizing the antioxidant from an oil containing a base oil that is a polar solvent and an antioxidant that is a polar solute,
Mixing the oil and the nonpolar solvent to produce a mixed solution containing the oil and the nonpolar solvent, wherein the oxidation product is precipitated;
A filtration step of filtering the mixed solution produced in the mixing step through a filter, and an oxidation product extraction method.   The method for extracting an oxidation product according to claim 1, wherein in the mixing step, the oil containing an amine-based antioxidant as the antioxidant is mixed with the nonpolar solvent.   3. The oxidation product according to claim 2, wherein in the mixing step, the oil containing N-phenyl-1-naphthylamine which is an amine-based antioxidant as the antioxidant is mixed with the nonpolar solvent. Extraction method.   The method for extracting an oxidation product according to any one of claims 1 to 3, wherein, in the mixing step, the oil and the nonpolar solvent having a dielectric constant of 1.92 or less are mixed.   5. The method for extracting an oxidation product according to claim 4, wherein in the mixing step, the oil is mixed with petroleum ether, hexane, pentane, or heptane, which is the nonpolar solvent.   In the mixing step, the oil and the petroleum ether are mixed by setting a mixing ratio of the oil and the petroleum ether as the nonpolar solvent at a volume ratio of oil: petroleum ether = 1: 100 or less. The method for extracting an oxidation product according to any one of claims 3 to 4. An extraction system for extracting an oxidation product produced by oxidation of the antioxidant from an oil containing a base oil that is a polar solvent and an antioxidant that is a polar solute,
An injection part for injecting a nonpolar solvent into the oil;
A reservoir for storing a mixed liquid containing the oil and the nonpolar solvent, in which the oxidation product is deposited;
An extraction system comprising: a filter that includes a filter and filters the liquid mixture stored in the storage through the filter.