JP6719896B2 - filter - Google Patents

Description

The present invention relates to a sheet-shaped filter that can determine the state of lubricating oil or water by filtering the lubricating oil or water.

Techniques for filters for filtration have been proposed. For example, Patent Document 1 discloses a film structure including a plurality of layers. The membrane structure includes a nanoweb and a support layer as multiple layers. Nanowebs are manufactured from polymer nanofibers. The average flow pore size of the nanoweb is in the range of 50 nm to 5 μm. The number average diameter of the nanofibers is in the range of 100 to 600 nm. The average flow pore size of the nanoweb decreases, for example, with increasing thickness or decreasing the number average diameter of the nanofibers. The basis weight of the nanoweb is in the range of 1 to ²⁰ g/m ² . The porosity of the nanoweb is in the range of 60-95%. The nanoweb has hydrophilicity. The average flow pore size of the support layer is made larger than the average flow pore size of the nanoweb. For example, the average flow pore size of the support layer is in the range of 5 to 100 μm. Patent Document 1 describes that the above-mentioned membrane structure is also used for wastewater purification, oil and fuel filtration.

Patent Document 2 discloses a filtration medium having a high flow rate and low adhesion. The filtration medium is a three-layer membrane composed of a non-woven nanofiber support material, a nanofiber base material, and a hydrophilic coating.

Inventor Tomoki Honda et al. proposes an oil condition monitoring method and an oil condition monitoring device in Patent Document 3 for monitoring the deterioration condition of oil used in a machine or equipment. In the oil condition monitoring method, oil is filtered by a filter. In the oil condition monitoring method, oil is filtered, and the oil component is removed from the filter that traps contaminants existing in the oil before filtration. In the oil condition monitoring method, the color component of the transmitted light, which is the light projected on the filter from which oil has been removed and transmitted through the filter, is detected. Further, in the oil state monitoring method, the color component of the reflected light that is the light projected on the filter from which the oil has been removed is reflected. The oil condition monitoring device includes a light source and a color sensor. The light source emits light that is captured by the contaminants and projected onto the degreased filter. The color sensor detects a color component of transmitted light in which light emitted from the light source passes 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 by the filter. In the example shown in this document, a membrane filter is used as the filter.

Inventor Hitoshi Mizuguchi et al. have proposed in Patent Document 4 a simple method for quantifying trace antimony ion species. In the simple quantification method, 10 mL of a sample solution containing antimony (V) ions is placed in a glass beaker and evaporated to dryness on a hot plate. After drying, the residue was dissolved in 1.5 mL of 36% hydrochloric acid, and a mixed solution was prepared by adding 10 mL of pure water and 0.25 mL of 1×10 ⁻⁴ mol/L Co(III)-5-Cl-PADAP complex aqueous solution. Then, it is passed through a conditioned PTFE membrane filter (ADVANTEC, pore size 0.5 μm). Then, 10 mL of 8% aqueous methanol solution is passed through in the same manner. Subsequently, the membrane filter is dried and the reflection absorbance is measured. In Patent Document 4, it has been confirmed that there is a first-order correlation between the reflection absorbance and the antimony (V) concentration, and it is said that such a quantification method has been proved to be extremely effective. There is.

Japanese Patent Publication No. 2013-534462 JP, 2011-183389, A Japanese Patent No. 5190660 JP, 2004-257806, A

When determining the state of the lubricating oil or water (for example, the degree of deterioration or the degree of pollution), the lubricating oil or water to be determined is filtered by a sheet-shaped filter. By shortening the time required for filtration, it is possible to shorten the time required for determining the state of the lubricating oil or water. For example, the lubricating oil is used in a predetermined machine provided on the spot such as a factory. Therefore, it is considered necessary to quickly determine the state of the lubricating oil. This also applies to the determination of the state of water as in the case of lubricating oil, and it is considered that the determination needs to be performed quickly.

For example, according to the oil condition monitoring method and the oil condition monitoring device disclosed in Patent Document 3, it is possible to quickly determine the condition of the lubricating oil for the filter obtained by filtering the lubricating oil. For example, ASTM D7843 specifies that a filter having a pore size of 0.45 μm should be used for filtering a lubricating oil so that a particulate matter in the oil can be filtered. Therefore, it is assumed that the lubricating oil is filtered using a known membrane filter having a pore diameter of 0.45 μm. In this case, even with a lubricating oil having a relatively low degree of deterioration, the filtration time may be about three times longer than when a known membrane filter having a pore diameter of 0.80 μm is used. In some cases, the degree of deterioration of the lubricating oil is slightly higher, and the filtration time becomes longer and filtration cannot be performed.

An object of the present invention is to provide a sheet-shaped filter which can smoothly filter a lubricating oil or water containing a fine particle substance and is used as a sample for judging the state of the lubricating oil or water.

One aspect of the present invention is a sheet-shaped filter used as a sample for judging the state of the lubricating oil or the water in a state where the lubricating oil or the water is filtered, and a fine particle having an average diameter of 50 to 800 nm. Porous fine fiber layers formed of fibers and having an amount of the fine fibers of 1.0 to 8.0 g/m ^2, and supporting the fine fiber layers, and having an average pore diameter of 1.0 to 5. 0 μm, a porous base material, wherein the fine fiber layer and the base material each have the same inlet pressure and the same filtration area of the lubricating oil or the water when used alone as a filter medium. It is a filter in which the original volume flow rate of the base material is higher than that of the fine fiber layer. In this case, the filter is in the filtration conditions and pressure 0.98MPa unused state, the amount of the lubricating oil passes through the filter to a single much time及beauty Unit per area, the lubricating oil is an average pore diameter May be 0.80 μm and the thickness is 0.125 mm , and may be equal to or larger than the amount that passes through the membrane filter made of acetyl cellulose . Moreover, in the fine fiber layer, the amount of the fine fibers may be 4.0 to 8.0 g/m ² .

According to this filter, it is possible to achieve both the capturing property of the particulate matter and the liquid permeability of the lubricating oil or water. It can be a filter with small pressure loss.

In the filter, the fine fiber layer may have a color having the same R value, the G value, and the B value, and the base material may have the same color as the fine fiber layer. According to the above method proposed by the inventors of the present application, the state of the lubricating oil or water can be determined from the change in the color of the filter before and after filtration. For example, in the oil condition monitoring method, the condition of the lubricating oil is determined by ΔE _RGB . According to the above configuration, it is possible to simplify the RGB value of the filter before filtration, which is a criterion for determination, and facilitate determination of the state of the lubricating oil or water.

In the filter, the fine fiber layer may be formed by the fine fiber made of any one of acetyl cellulose, polyvinyl alcohol, polyacrylonitrile, polyurethane and polyamide 6. In this case, the fine fiber layer may be formed of the fine fiber of any one of acetyl cellulose, polyvinyl alcohol, polyacrylonitrile, polyurethane and polyamide 6. According to this configuration, the filter can be stable against lubricating oil or water. For example, a filter that does not swell in water can be used.

In the filter, the fine fiber layer and the base material may be partially bonded. Here, for example, an adhesive layer made of an adhesive may be provided over the entire surface between the fine fiber layer and the base material. However, the liquid permeability may decrease due to the adhesive layer. According to this configuration, it is possible to suppress the separation of the fine fiber layer from the base material while ensuring the liquid permeability of the lubricating oil or water.

According to the present invention, it is possible to obtain a sheet-shaped filter which can be smoothly filtered for lubricating oil or water containing fine particle substances and is used as a sample for judging the state of lubricating oil or water.

It is a figure which shows an example of a schematic structure of a filter. The upper row shows the fine fiber layer. The middle row shows the substrate. The lower stage shows a filter in which a fine fiber layer is provided on the surface of a substrate. It is a surface expansion photograph of a membrane filter (Samples A to C) having a one-layer structure having no fine fiber layer. It is a figure which shows an example of schematic structure of a filtration apparatus. It is a figure which shows the principle of color measurement. FIG. 5 is a diagram showing experimental results of Experiment 1 of Example 1. Samples A to C corresponding to known membrane filters are targeted. FIG. 5 is a diagram showing experimental results of Experiment 1 of Example 1. Samples 1 to 6 corresponding to the filter of the embodiment are targeted. FIG. 5 is a diagram showing experimental results of Experiment 2 of Example 1. The sample liquid is used turbine oil. The measurement light from the color sensor is transmitted light. FIG. 5 is a diagram showing experimental results of Experiment 2 of Example 1. The sample liquid is used turbine oil. The measurement light from the color sensor is reflected light. FIG. 5 is a diagram showing experimental results of Experiment 2 of Example 1. The sample liquid is RPVOT oil. The measurement light from the color sensor is transmitted light. FIG. 5 is a diagram showing experimental results of Experiment 2 of Example 1. The sample liquid is RPVOT oil. The measurement light from the color sensor is reflected light. FIG. 5 is a diagram showing an experimental result of Example 2. The sample liquid is filtered and the appearance of the colored filter is shown. The sample 7 corresponding to the filter of the embodiment is targeted. FIG. 5 is a diagram showing an experimental result of Example 2. The relationship between the reflection absorption intensity and the arsenic (III) concentration is shown.

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 adopted 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.

<Filter>
The filter 11 will be described with reference to FIG. The filter 11 is a sheet-shaped filter that filters a liquid. The filter 11 is a sample for judging the liquid state in a state where the liquid is filtered. For example, assume that the object of filtration is lubricating oil. In this case, as an inspection provided with the filter 11, an oil state monitoring method performed by using the oil state monitoring device shown in the above-mentioned Patent Document 3 is exemplified. The embodiment will be mainly described by taking a case where a lubricating oil is an object of filtration as an example. As the lubricating oil, for example, turbine oil or a lubricating oil having a viscosity equal to or lower than that of the turbine oil is targeted for filtration.

The filter 11 includes a fine fiber layer 12 and a base material 13. That is, the filter 11 is a sheet-shaped filter having a two-layer structure including the fine fiber layer 12 and the base material 13. In the filter 11, the fine fiber layer 12 is directly laminated on the base material 13 without an adhesive layer made of an adhesive. However, the fine fiber layer 12 and the base material 13 may be bonded by an adhesive.

The fine fiber layer 12 is a porous layer formed of fine fibers. The fine fibers forming the fine fiber layer 12 are fibers having an average diameter in the range of 50 to 800 nm. The length of the fine fibers is indefinite. However, the length of the fine fibers may be a predetermined fixed length. When the average diameter of the fine fibers is 100 nm or less and the length is 100 times or more the diameter, the fine fibers are called nanofibers. In this case, the fine fiber layer 12 can be referred to as a nanofiber layer. The amount of fine fibers forming the fine fiber layer 12 is set to a predetermined value in the range of 1.0 to 8.0 g/m ² . The amount of fine fibers will be described later. The fine fibers can be formed by any of the known force spinning method and electrospinning method. Alternatively, it can be produced by a conventional spinning method using a nozzle. The material of the fine fibers is a plastic material that does not dissolve in petroleum ether and does not swell in water. For example, the material of the fine fibers is any one of acetyl cellulose, polyvinyl alcohol, polyacrylonitrile, polyurethane and polyamide 6.

It is considered that the material of the fine fibers is preferably a material having a work function that facilitates flow electrification. According to the fine fibers made of such a material, electrostatic attraction to the fine fibers is likely to occur, and an effect of enhancing the collection efficiency of the burnish precursor or the like having a pore size smaller than the pore diameter of the fine fiber layer 12 can be expected.

The base material 13 is a porous layer that supports the fine fiber layer 12. The material of the base material 13 is, for example, acetyl cellulose. In addition, the base material 13 may be formed of rayon. The material of the base material 13 may be the same material as the fine fibers. For example, the fine fiber layer 12 may be formed of fine fibers of acetyl cellulose, and the base material 13 may be formed of acetyl cellulose. The average pore diameter of the base material 13 is, for example, a predetermined value in the range of 1.0 to 5.0 μm.

In the filter 11, the fine fiber layer 12 has a color having the same R value, G value, and B value, and the base material 13 has the same color as the fine fiber layer 12. The RGB values of the fine fiber layer 12 and the base material 13 are color values that are used as a reference for calculating ΔE _RGB described later. For example, when calculating ΔE _RGB with white (R255, G255, B255) as a reference, the RGB values of the fine fiber layer 12 and the base material 13 are R255, G255, B255.

In the filter 11, the amount of liquid filtered is as follows. That is, in the filter 11, the amount of lubricating oil passing through the filter 11 per unit time and unit area under a predetermined filtering condition is such that the lubricating oil has an average pore diameter of 0.80 μm and a thickness of 0.125 mm. More than the amount that passes through the membrane filter of. Further, in the filter 11, the fine fiber layer 12 and the base material 13 have the same inlet pressure and the same filtration area of the liquid to be filtered, such as lubricating oil or water, when they are used alone as a filter medium. In the combination, the volume flow rates of and are larger in the base material 13 than in the fine fiber layer 12.

<Example>
In order to confirm the effectiveness of the filter 11 of the embodiment, an experiment was conducted using lubricating oil and water as sample liquids. Therefore, the experiment conducted this time will be described below.

<Example 1>
As Example 1, Experiment 1 and Experiment 2 using a lubricating oil as a sample liquid will be described with reference to FIGS. In the first embodiment, the nine types of target filters are "sample A", "sample B", "sample C", "sample 1", "sample 2", "sample 3", "sample 4", and "sample 4", respectively. These are referred to as “Sample 5” and “Sample 6”. In the first embodiment, the filters of Samples A to C and Samples 1 to 6 are referred to as “filter F” when they are not distinguished or are collectively referred to.
1. Experimental method (1) Filter Samples A to C are known filters (membrane filter manufactured by ADVANTEC) having a one-layer structure having no fine fiber layer. Regarding Samples A to C, the diameter is 25 mm and the material is acetyl cellulose. The differences between the samples A to C are the pore diameter (see FIG. 2) and the thickness. The pore diameters, thicknesses and product names of Samples A to C are as follows.
<Pore size, thickness and model number>
Sample A 3.0 μm (pore size)
0.135 mm (thickness)
C300A025A (product name)
Sample B 0.80 μm (pore size)
0.125 mm (thickness)
C080A025A (product name)
Sample C 0.45 μm (pore size)
0.125 mm (thickness)
C045A025A (Product name)
Samples 1 to 6 are filters having a two-layer structure similar to the filter 11 of the above-described embodiment. The diameter of Samples 1-6 is 25 mm. In Samples 1 to 6, the base materials are the same. The base materials in Samples 1 to 6 are as follows.

<Substrate>
Material Acetyl cellulose Pore diameter 3.0μm
Thickness 0.13 mm
The material of the fine fibers in Samples 1 to 6 is acetyl cellulose. The fine fibers have a diameter of 100 to 300 nm and their length is indefinite. The difference between Samples 1 to 6 is the amount of fine fibers attached to the base material (fine fiber attachment amount). The fine fiber adhesion amount in Samples 1 to 6 is as follows. In FIG. 4, as the filter F, a filter (samples 1 to 6) having a two-layer structure similar to the filter 11 is shown.
<Amount of fine fibers attached>
Sample 1 1.0 g/m ²
Sample 2 1.5 g/m ²
Sample 3 2.0 g/m ²
Sample 4 4.0 g/m ²
Sample 5 6.0 g/m ²
Sample 6 8.0 g/m ²
Each of the samples 1 to 6 was manufactured as follows. That is, a solution of a cellulose acetate resin (manufactured by Daicel Chemical Industries, Ltd., model number: L-20) in N,N-dimethylacetamide (DMAc) at a concentration of 20 mass% was used, and a known electrospinning method (Elmarco) was used. Samples 1 to 6 were produced by adhering fine fibers to the base material using a model number: NS LAB500) manufactured by the company.

In Experiment 1, all of the above-mentioned samples A to C and samples 1 to 6 were targets. In Experiment 2, among the nine types of filters F described above, samples A to C and sample 4 were targeted. In Experiment 2, among the Samples 1 to 6, Sample 4, which gave the suitable result in Experiment 1, was selected as the experiment target.

(2) Sample Liquid The lubricating oil used as the sample liquid in Experiment 1 was the turbine oil actually used in a thermal power plant (FBK turbine 32 manufactured by JX Nikko Nisseki Energy Co., Ltd.). The lubricating oil used as the sample liquid in Experiment 2 was the turbine oil used in Experiment 1 and an oxidized oil obtained by oxidizing a new oil of this turbine oil by the RPVOT method. In Example 1, the oxidized oil oxidized by the RPVOT method used in Experiment 2 is referred to as “RPVOT oil”. The characteristics of the FBK turbine 32 manufactured by JX Nikko Nisseki Energy Co., Ltd. used in Experiments 1 and 2 are as follows.
<Characteristics of FBK turbine 32>
Kinematic viscosity (40° C.) 31.9 mm ² /sec Kinematic viscosity (100° C.) 5.9 mm ² /sec Viscosity index 131
Flash point (C0C) 240°C
Pour point -17.5°C
The outline of the production of oxidized oil by the RPVOT method will be described. An RPVOT tester was used to prepare the sample liquid. During production, distilled water was added to fresh turbine oil. A sample beaker storing a fresh turbine oil containing distilled water was housed in the pressure chamber of the RPVOT tester, heated at a predetermined temperature, and rotated at a predetermined speed. At that time, distilled water was also put in the pressure chamber. The addition of distilled water to the new oil and the pressure chamber takes into consideration that water may be mixed with the oil and deteriorate the oil in the actual use scene. The lowering pressure amount of oxygen existing together with the fresh oil of the turbine oil was set to 10 PSI (pound-force per square inch). 1 PSI is 6894.76 Pa. The experimental conditions of the RPVOT method are as follows.
<Experimental condition of RPVOT method>
Lubricant amount (g): 50±0.5
Distilled water amount (g): 5 (sample beaker)
5 (pressure chamber)
Temperature (℃): 150
Rotation speed (rpm): 100±5
The RPVOT tester is a known device. Therefore, description regarding this is omitted. However, the RPVOT tester used in the experiment did not use a copper coil used as a catalyst. This is to prevent the copper oxide deposited by the copper coil used as the catalyst from affecting the color of the filter F after filtration.

The turbine oil manufactured by JX Nikko Nisseki Energy Co., Ltd. includes FBK turbines 46, 56, 68, 100 in addition to the above FBK turbine 32. The kinematic viscosity of each of these turbine oils is as follows.
<Kinematic viscosity and viscosity index of FBK turbine>
FBK Turbine 46 45.3 mm ² /sec (Kinematic viscosity (40°C))
7.3 mm ² /sec (Kinematic viscosity (100°C))
124 (viscosity index)
FBK Turbine 56 54.2 mm ² /sec (Kinematic viscosity (40°C))
8.1 mm ² /sec (Kinematic viscosity (100°C))
118 (viscosity index)
FBK Turbine 68 67.2 mm ² /sec (Kinematic viscosity (40°C))
9.1 mm ² /sec (Kinematic viscosity (100°C))
111 (viscosity index)
FBK Turbine 100 99.2 mm ² /sec (Kinematic viscosity (40°C))
11.5 mm ² /sec (Kinematic viscosity (100°C))
104 (viscosity index)
(3) Filtration Device The filtration device 20, as shown in FIG. 3, includes a dustproof lid 21, a cylinder 22, a flask 23, and a vacuum pump 24. The filters F of Samples A to C and Samples 1 to 6 described above are mounted between the cylinder 22 and the flask 23, respectively. Regarding the attachment of Samples 1 to 6, Samples 1 to 6 are attached with the fine fiber layer on the cylinder 22 side and the base material on the flask 23 side.

The filtration of each sample solution described above was performed by storing the sample solution in the cylinder 22 and directly depressurizing the inside of the flask 23 with the vacuum pump 24. As the vacuum pump 24, a vacuum pump having a capability of achieving a vacuum of −0.033 MPa was used. Therefore, the pressure (reference value) in the flask 23 in Experiment 1 and Experiment 2 is 0.98 MPa (1.013 MPa-0.033 MPa). In FIG. 3, the halftone dot pattern shown in the filtration device 20 indicates the sample liquid. That is, in FIG. 3, the halftone dot pattern above the filter F shows the sample liquid before filtration. The halftone dot pattern below the filter F indicates the sample liquid after filtration. In the experiment, in the filter F, the region R (see FIG. 4) for filtering the sample liquid has a diameter of about 18 mm (area: about 992 mm ² ).

After the filtration was completed, the filter F was removed from the filtration device 20. Oil was removed from the filter F removed from the filtration device 20. Petroleum ether was used to remove oil. Then, the filter F was dried.

(4) Oil state determination In order to determine the state of the sample liquid, the color of the filter F was quantitatively measured. The area of the filter F that is the object of color measurement is the area R that is colored by capturing the particulate matter contained in the sample liquid. The color determination in the region R of the filter F was performed by the method proposed by the inventor Tomoki Honda in Patent Document 3. In this method, for example, white light is projected on the filter F from the front surface or the back surface side of the filter F, and the transmitted or reflected light of the projected white light is measured by the color sensor 30 (see FIG. 4). .. As the color sensor 30, for example, a hue discriminating device (CPA Colorimetric patch Analyzer) developed by Tomomi Honda et al. can be adopted. In this experiment, this device was adopted as the color sensor 30. In the first embodiment, when the filter F is set in the filtering device 20 (see FIG. 3 ), the surface on the cylinder 22 side is the front surface of the filter F and the surface on the flask 23 side is the back surface of the filter F. There is. In Samples 1 to 6, the surface on the side of the fine fiber layer is the front surface and the surface on the side of the base material is the back surface.

In the method described above, for example, the color (RGB value) of the contaminant captured on the surface of the filter F can be clarified by the reflected light reflected on the surface of the filter F. The transmitted light transmitted from the back surface side to the front surface side of the filter F can reveal the color (RGB value) of the contaminants captured on the front surface and the inside of the filter F. From the RGB values of transmitted light or reflected light measured by the color sensor 30, MCD and ΔE _RGB are calculated.

MCD is the maximum color difference between two colors of the measured values of RGB. By determining the MCD, the deterioration factor of the lubricating oil can be roughly specified. For the MCD, for example, it is assumed that the RGB values are R253, G240, and B223 (see “Sample 4” in FIG. 6 described later). The MCD at this time is 30 (R253-B223). For example, the deterioration factor when the MCD is 20 to 30 or less is stain, and the deterioration factor when the MCD is 100 or more is oxidation.

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. This time, ΔE _RGB is the distance from white (R255, G255, B255). However, ΔE _RGB can also be defined as the distance from black (R0, G0, B0) as in Patent Document 3. The details of the method proposed by the inventors are disclosed in Patent Document 3. Therefore, other explanations regarding this will be omitted. By using such a method, the degree of deterioration of the antioxidant contained in the oil can be determined easily and quickly. The cost can also be reduced.

In Experiment 1, white light was projected from the back surface side of the filter F, and the transmitted light that was transmitted from the white light to the front surface side of the filter F was measured by the color sensor 30. Therefore, the RGB values in FIGS. 5 and 6 showing the experimental results of Experiment 1 are the R value, G value, and B value of the transmitted light, and MCD is the maximum color difference between the two colors in such RGB values. , ΔE _RGB are values obtained by the above equation (1) from such RGB values.

In Experiment 2, white light was projected from the back surface or the front surface side of the filter F. That is, when white light was projected from the back surface side of the filter F, the transmitted light that was transmitted to the front surface side of the filter F was measured by the color sensor 30. Therefore, the RGB values in FIGS. 7 and 9 showing the experimental results of Experiment 2 are the R value, G value, and B value of the transmitted light, and MCD is the maximum color difference between the two colors in such RGB values. , ΔE _RGB are values obtained by the above equation (1) from such RGB values. When white light was projected from the surface side of the filter F, the reflected light reflected from the surface of the filter F by this white light was measured by the color sensor 30. Therefore, the RGB values in FIGS. 8 and 10 showing the experimental results of Experiment 2 are the R value, G value, and B value of the transmitted light, and MCD is the maximum color difference between the two colors in such RGB values. , ΔE _RGB are values obtained by the above equation (1) from such RGB values. The appearance of the filter F (reference numeral “F” is omitted) shown in FIGS. 5 to 10 is the surface of the filter F.
2. Experimental results and consideration (1) Experiment 1
(1-1) Filter appearance, MCD and ΔE _RGB
In each of Samples A to C, the region R of the filter F was in a lightly colored state (see FIG. 5). In Samples A to C, MCD and ΔE _RGB show higher values as the average pore size decreases. However, in samples A to C, the filtration time becomes longer as the average pore size becomes smaller.

In Samples 1 to 6 as well, similar to Samples A to C, the region R of the filter F was in a lightly colored state (see FIG. 6). In Samples 1 to 3, the MCD was 20 or less, and the value of 23 in Sample 2 was the highest for ΔE _RGB . In Sample 4, MCD was 30 and ΔE _RGB was 35. In samples 5 and 6, MCD was 23. The ΔE _RGB of sample 5 was 25, and the ΔE _RGB of sample 6 was 31. In sample 4, ΔE _RGB was equivalent to sample C, in sample 5, ΔE _RGB was the same as sample B, and in sample 6, ΔE _RGB was higher than sample B. In Samples 1 to 6, the filtration time was all within 5 minutes, which was shorter than that of Sample B. In Samples 1 to 5, the filtration time was about 3 minutes, which was equivalent to that of Sample A.

(1-2) Consideration (I) In Sample A and Sample 1, the filtration time was 3.18 minutes (see FIGS. 5 and 6). From this, in Sample 1, when the fine fiber layer and the base material are used alone as the filter medium, the volume flow rate of the sample oil under the same inlet pressure and the same filtration area is the same as that of the fine fiber layer. It is recognized that the combinations are equal in the substrates. On the other hand, in Samples 2 to 6, the filtration time is longer than that in Sample 1. Therefore, in Samples 2 to 6, when the fine fiber layer and the base material were used alone as a filter medium, the volume flow rate of the sample oil under the same inlet pressure and the same filtration area was smaller than that of the fine fiber layer. It is recognized that this is a combination in which the base material is more numerous.

(II) Sample C is capable of efficiently capturing particulate matter (burnish precursor in lubricating oil and trace metal ions in water) contained in turbine oil that was actually used in a thermal power plant, and uses a hue discriminating device. Excellent MCD and ΔE _RGB can be obtained in determining the oil state (see FIG. 5). However, sample C has a long filtration time of 34.93 minutes. Therefore, Sample C is considered unsuitable for actual field use. Among the conventional products, the sample B can obtain a well-balanced result in terms of both the measurement result (MCD and ΔE _RGB ) of the oil state determination using the hue determination device and the filtration time.

(III) Among Samples 1 to 6, Samples 4 to 6 can obtain the same excellent results as Sample B in terms of both MCD and ΔE _RGB and filtration time. In Sample 4, although the fine fiber adhesion amount was set smaller than in Samples 5 and 6, MCD and ΔE _RGB showed the highest values, and favorable measurement results were obtained. The filtration time of Sample 6 is 4.93 minutes, which is the longest among Samples 4 to 6, but is shorter than 7.43 minutes of Sample B. Samples 1 to 3 have ΔE _RGB of 21 to 23 (see FIG. 6 ), which is a lower value than Samples 4 to 6. Therefore, based on the result of the experiment 1, it is considered that the oil state determination can be made more appropriately by using the samples 4 to 6 than by using the samples 1 to 3.

(2) Experiment 2
(2-1) Filter appearance, MCD and ΔE _RGB
<Sample oil: Used turbine oil Measuring light: Transmitted light>
In Sample 4 and Samples A to C for which suitable measurement results were obtained in Experiment 1, the region R of the filter F was in a lightly colored state (see FIG. 7). Regarding MCD, Sample 4 had a low value as compared with Samples A to C. In Samples A to C, Sample A showed the highest value, and Samples B and C had the same value. Regarding ΔE _RGB , Sample 4 showed a lower value than Samples A to C. Samples A to C had equivalent values. Regarding the filtration time, although the sample 4 required a longer time than the shortest sample A among the samples A to C, it was an equivalent time. In addition, among the samples A to C, the filtration time of the sample C was the longest.

<Sample oil: Used turbine oil Measuring light: Reflected light>
In each of Sample 4 and Samples A to C, the region R of the filter F was in a lightly colored state (see FIG. 8). Regarding MCD, Sample 4 had a value equivalent to that of Samples B and C, which showed high values among Samples A to C. In Samples A to C, Sample A showed a lower value than Samples B and C, and Samples B and C had equivalent values. Regarding ΔE _RGB , Sample 4 had the same values as Samples B and C that showed the highest value among Samples A to C. In samples A to C, sample A showed a lower value than samples B and C, and samples B and C had the same value. Regarding the filtration time, although the sample 4 required a longer time than the shortest sample A among the samples A to C, it was the same time as the sample A and shorter than half of the sample B. In addition, among the samples A to C, the filtration time of the sample C was the longest.

<Sample oil: RPVOT oil Measuring light: Transmitted light>
In the sample 4 and the samples A to C, the region R of the filter F was in a deeply colored state (see FIG. 9). Regarding MCD, Sample 4 had a low value as compared with Samples A to C. In Samples A to C, Samples A and B showed the highest value, and Sample C had a lower value than Samples A and B. Regarding ΔE _RGB , Sample 4 showed a lower value than Samples A to C. In Samples A to C, Sample A showed the highest value and Samples B and C had the same value. Regarding the filtration time, the sample 4 had a time equivalent to that of the sample B, but required a time about 8.5 times longer than that of the shortest sample A among the samples A to C. In addition, among the samples A to C, the filtration time of the sample C was the longest.

<Sample oil: RPVOT oil Measuring light: Reflected light>
In each of Sample 4 and Samples A to C, the region R of the filter F was in a deeply colored state (see FIG. 10). Regarding MCD, Sample 4 had a value equivalent to that of Samples B and C, which showed high values among Samples A to C. In Samples A to C, Sample A showed a lower value than Samples B and C, and Samples B and C had equivalent values. Regarding ΔE _RGB , Sample 4 had values equivalent to those of Samples B and C that showed high values among Samples A to C. In Samples A to C, Sample A showed a lower value than Samples B and C, and Samples B and C had equivalent values. Regarding the filtration time, the sample 4 had a time equivalent to that of the sample B, but required a time about 8.5 times longer than that of the shortest sample A among the samples A to C. In addition, among the samples A to C, the filtration time of the sample C was the longest.

(2-2) Consideration (I) In sample 4, it was possible to obtain MCD and ΔE _RGB equivalent to those of samples A to C in measurement by reflected light. It is considered that this is because, for example, the trapping mechanism differs depending on the degree of oxidation of the turbine oil used as the sample oil and/or the size of the oxidation product, and a difference appears in the relationship between reflected light and transmitted light. The oxidation product is generated, for example, by oxidizing an antioxidant contained in turbine oil.

(II) In sample 4, when the RPVOT oil was used as the sample oil, the filtration time was long at 40.9 minutes. When the oil state determination is performed on turbine oil whose oxidation has progressed, it is preferable to use a filter having a smaller amount of fine fiber adhesion than Sample 4 (fine fiber adhesion amount: 4.0 g/m ² ). It is considered that this makes it possible to achieve both a favorable measurement result and an improvement in filtration time. For example, when a turbine oil that has undergone oxidation is used for the oil state determination, it is considered possible to use a filter equivalent to that of Sample 1 (fine fiber adhesion amount: 1.0 g/m ² ).

<Example 2>
As Example 2, an experiment using water as a sample solution will be described with reference to FIGS. 11 and 12.
1. Experimental Method (1) Sample Solution In this experiment, 2 mL of a solution containing 5 μg/L of arsenic (III), 5 mL of a solution containing 10 μg/L, 5 mL of a solution containing 25 μg/L, and 5 mL of a solution containing 50 μg/L were used. 0.1 mL of a 0.5 mol/L nitric acid aqueous solution and 0.02 mL of a 0.01 mol/L sodium dibenzyldithiocarbamate solution were sequentially added, and a liquid that was allowed to stand at room temperature for 10 minutes was used as a sample solution.

(2) Filter The filters used for measurement are as follows. Sample D is a known filter (CAT No. GNWP02500 manufactured by Merck Millipore) having a single-layer structure having no fine fiber layer. Sample 7 is a filter having a two-layer structure similar to the filter 11 of the above-described embodiment.
<Sample D>
Pore diameter 0.2 μm
Diameter 25mm
Thickness 0.17 mm
<Sample 7>
Material (base material) Rayon non-woven fabric Pore size 250 μm (bubble point method)
Material (fine fiber) Nylon 6 type resin Fine fiber adhesion amount 1.0 g/m ²
The sample 7 was manufactured as follows. That is, a known force spinning method (manufactured by FiberRio Co., Ltd. model number: Fiber 7 was prepared by attaching fine fibers to the base material by using Fiberlab L1000).

(3) Filtration Method and Measurement Method For filtration, a vacuum filter having the same configuration as the filtration device 20 shown in FIG. 3 was used. This vacuum filter is similar to the filtering device 20, and therefore its description is omitted.

To filter the sample solution, set the sample D or sample 7 in the vacuum filter and reduce the sample solution from the atmospheric pressure by the suction pressure shown in Table 1 in association with the "first passage". The sample D or the sample 7 set in the filter was made to pass. In Example 2, this first passage is called the first passage. The effective filtration diameter in the first passage was 4.0 mm. Subsequently, the sample D or the sample 7 set in the vacuum filter is left as it is, and 0.1 mL of a 0.01 mol/L copper nitrate aqueous solution is further added to the funnel (corresponding to the "cylinder 22" in FIG. 3). In addition, it was left to stand for 5 minutes. After the lapse of 5 minutes, the copper nitrate aqueous solution in the funnel was depressurized from the atmospheric pressure by the suction pressure shown in relation to the “second passage” in Table 1, and the sample D or the sample 7 set in the depressurization filter was used. Liquid was passed through. In Example 2, this second liquid passage is referred to as the second liquid passage.

The arsenic complex is captured in the sample D or sample 7 set in the vacuum filter by the first passage. According to the second liquid passing, the sample D or the sample 7 in which the arsenic complex is captured can be colored. In each of Sample D or Sample 7, the filtration time required for the first liquid passage was within the range shown in Table 1 in association with the "first liquid passage". In each of Sample D or Sample 7, the filtration time required for the second liquid passage was the time shown in Table 1 in association with the "second liquid passage".

Then, the sample D or sample 7 set in the vacuum filter was removed from the vacuum filter and dried at room temperature for 30 minutes.

Next, a sample D and a sample 7 were subjected to measurement using a chromatoscanner (model: CS-9300PC manufactured by Shimadzu Corporation). The measurement wavelength was 447 nm.
2. Experimental Results and Consideration (1) Appearance of Filter Sample 7 which was removed from the vacuum filter after the second liquid passing and dried at room temperature for 30 minutes was in a state shown in FIG. 11. That is, it can be seen that the higher the concentration of arsenic (III) in the sample liquid, the darker the colored state of the effective filtration region of Sample 7. The aforementioned effective filtration area is an area corresponding to the area R in FIG.

(2) Relationship between reflection absorption intensity and arsenic (III) concentration When sample D is used even if sample 7 is used for filtration and filtration is completed in a short time under a lower suction pressure than when sample D is used On the other hand, it can be seen that a good density correlation comparable to that obtained is obtained (see FIG. 12).

(3) Consideration When the object to be filtered is water, the amount of fine fibers adhered to the fine fiber layer of the filter having the same two-layer structure as the filter 11 of the embodiment can obtain a suitable measurement result in Experiment 1 of Example 1. It can be set to 1.0 g/m ² or more, which is less than 4.0 g/m ² of the obtained sample 4.

<Effect of this embodiment>
According to this embodiment, the following effects can be obtained.

(1) In the filter 11, the fine fiber layer 12 is formed of fine fibers having an average diameter of 50 to 800 nm. In the fine fiber layer 12, the amount of fine fibers is 1.0 to 8.0 g/m ² . In the filter 11, the fine fiber layer 12 and the base material 13 have the same volumetric flow rate under the same inlet pressure and the same filtration area of the lubricating oil or water when they are used alone as a filter medium. The combination of the base material 13 is larger than that of the base material 13. Therefore, according to the filter 11, both the trapping property of the particulate matter and the liquid permeability of the lubricating oil or water can be achieved. It can be a filter with small pressure loss.

(2) In the filter 11, the fine fiber layer 12 has a color having the same R value, G value, and B value. The base material 13 has the same color as the fine fiber layer 12. Therefore, according to the filter 11, for example, as in Example 1 or Example 2 described above, lubrication is performed from the colored state of the region of the filter 11 (see “region R” in FIG. 4) in which the lubricating oil or water is filtered. The state of oil or water can be determined. It is possible to simplify the RGB values of the filter 11 before filtration, which is a criterion for determination, and facilitate determination of the state of the lubricating oil or water.

Based on this point, the filter 11 can be specified as the following filter. That is, the filter 11 is a filter including a porous fine fiber layer 12 and a porous base material 13 that supports the fine fiber layer 12 and has a color in which the R value, the G value, and the B value are the same value. You can also specify. In this case, the fine fiber layer 12 may be formed of fine fibers having an average diameter of 50 to 800 nm, as described above. In the fine fiber layer 12, the amount of fine fibers may be 1.0 to 8.0 g/m ² as in the above.

(3) In the filter 11, the fine fiber layer 12 is formed of fine fibers made of any one of acetyl cellulose, polyvinyl alcohol, polyacrylonitrile, polyurethane, and polyamide 6. Therefore, the filter 11 can be a stable filter against lubricating oil or water. For example, a filter that does not swell in water can be used.

<Modification>
The embodiment may also be as follows. Some of the configurations of the modified examples described below can be appropriately combined and employed. The points different from the above will be described below. The description of the same points as above is omitted as appropriate.

(1) In the above, the material of the fine fibers forming the fine fiber layer 12 is one type. The fine fiber layer may be formed of two or more kinds of fine fibers made of different materials. In this case, the amount of each fine fiber forming the fine fiber layer may be the same for each material, or may be different for each material. The material of the fine fibers forming the fine fiber layer may be appropriately determined in consideration of various conditions. When two or more kinds of fine fibers are used, the amount of each material is appropriately determined in consideration of various conditions.

(2) In the above, in the filter 11, the fine fiber layer 12 and the base material 13 are directly laminated without an adhesive layer made of an adhesive, or adhered by an adhesive. In addition, in the filter, the fine fiber layer 12 and the base material 13 may be partially joined. For example, the fine fiber layer 12 and the base material 13 may be fixed by spot welding using ultrasonic waves. According to such a filter, peeling of the fine fiber layer 12 from the base material 13 can be suppressed while ensuring the liquid permeability of the lubricating oil or water.

(3) With respect to the above-described examples, in Example 1, the fine fiber material and the base material of Samples 1 to 6 were acetyl cellulose. In Example 2, the fine fiber material of Sample 7 was nylon 6 resin, and the base material was rayon nonwoven fabric. As long as the material of the fine fibers and/or the material of the base material is the material described in the description of the filter 11, it is possible to obtain the same experimental result as that of the samples 1 to 7 even if the material is different from the samples 1 to 7. Is considered to be.

11 filter, 12 fine fiber layer, 13 substrate 20 filtration device, 21 dustproof lid, 22 cylinder, 23 flask 24 vacuum pump, 30 color sensor, F filter, R area

Claims (7)

In the state of filtering the lubricating oil or water, a sheet-shaped filter that is a sample for the determination of the state of the lubricating oil or the water,
A porous fine fiber layer formed of fine fibers having an average diameter of 50 to 800 nm, the amount of the fine fibers being 1.0 to 8.0 g/m ² ;
A porous base material that supports the fine fiber layer and has an average pore size of 1.0 to 5.0 μm ;
The fine fiber layer and the base material each have a volume flow rate under the same inlet pressure and the same filtration area of the lubricating oil or the water, when used as a filter medium alone, as compared with the fine fiber layer. A filter in which the combination of the base material is larger. The filter in the filtration conditions and pressure 0.98MPa unused state, the amount of the lubricating oil passes through the filter to a single much time及beauty Unit per area, the lubricating oil is an average pore diameter of 0. The filter according to claim 1, which has a thickness of 80 μm and a thickness of 0.125 mm , and is equal to or larger than an amount that passes through a membrane filter made of acetyl cellulose . The filter according to claim 1, wherein the fine fiber layer has an amount of the fine fibers of 4.0 to 8.0 g/m ² . The fine fiber layer has a color in which the R value, the G value, and the B value are the same value,
The filter according to any one of claims 1 to 3, wherein the substrate has the same color as the fine fiber layer. The filter according to any one of claims 1 to 4, wherein the fine fiber layer is formed by the fine fiber made of any one of acetyl cellulose, polyvinyl alcohol, polyacrylonitrile, polyurethane, and polyamide 6. .. The filter according to claim 5, wherein the fine fiber layer is formed of the fine fiber of any one of acetyl cellulose, polyvinyl alcohol, polyacrylonitrile, polyurethane, and polyamide 6. The filter according to any one of claims 1 to 6, wherein the fine fiber layer and the base material are partially bonded to each other.