Apparatus for evaluating the physical properties of porous membranes, method for evaluating the physical properties of porous membranes, apparatus for manufacturing porous membranes, and method for manufacturing air filter media.

Abstract

The present invention provides a device for evaluating the physical properties of porous membranes, a method for evaluating the physical properties of porous membranes, a device for manufacturing porous membranes, and a method for manufacturing air filter media. [Solution] A physical property evaluation apparatus (50) for a porous film (31) is provided, which includes an evaluation unit (54e, 51) that determines physical property evaluation data (54f) of at least one of the pressure loss and film thickness of the porous film (31) based on optical data (54a, 54b) of the porous film (31).

Description

Technical Field

[0001] The present disclosure relates to a physical property evaluation apparatus for a porous membrane, a method for evaluating physical properties of a porous membrane, a manufacturing apparatus for a porous membrane, and a method for manufacturing an air filter filter medium.

Background Art

[0002] Conventionally, in order to obtain a desired porous membrane, for example, like the air filter filter medium described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2020-163311), adjusting various manufacturing conditions has been studied.

Disclosure of the Invention

Problems to be Solved by the Invention

[0003] n this way, for a porous membrane manufactured according to various manufacturing conditions, by actually setting it in a measuring device and performing a ventilation test to measure the pressure loss, it is confirmed whether the pressure loss is a desired value. Also, regarding the film thickness of the manufactured porous membrane, by actually setting it in a device for measuring the film thickness and performing a measurement test, it is confirmed whether the film thickness is a desired value.

[0004] Regarding physical properties such as the pressure loss and film thickness of such a porous membrane, it is desired to enable evaluation of the physical properties without depending on a measuring device (such as a pressure loss measuring device or a film thickness measuring device) that measures the physical properties themselves.

Means for Solving the Problems

[0005] The physical property evaluation apparatus for a porous membrane according to the first aspect includes an evaluation unit. The evaluation unit obtains physical property evaluation data of at least one of the pressure loss and the film thickness of the porous membrane based on the optical data of the porous membrane.

[0006] Note that the optical data may be image data of the porous membrane, or optical property data obtained by representing the difference in the values of optical properties as a difference in color or color shade from the image data of the porous membrane, or data including both of these.

[0007] This physical property evaluation device evaluates the properties of a porous film by using the relationship between the optical data of the porous film and at least one of its physical properties, such as pressure loss and film thickness. Therefore, it is possible to evaluate the physical properties of a porous film without using a measuring device that directly measures the physical properties themselves.

[0008] The porous film property evaluation apparatus relating to the second perspective is the porous film property evaluation apparatus relating to the first perspective, wherein the optical data is two-dimensional optical data of the porous film. The property evaluation data is property distribution evaluation data. The property distribution evaluation data is data of at least one of the pressure loss distribution and the film thickness distribution in the porous film when the porous film is viewed from the film thickness direction of the porous film.

[0009] This physical property evaluation device makes it possible to evaluate at least one of the pressure loss distribution and film thickness distribution of a porous film by performing evaluations based on two-dimensional optical data of the porous film.

[0010] The porous membrane property evaluation apparatus relating to the third perspective is the porous membrane property evaluation apparatus relating to the second perspective, further comprising an output unit. The output unit outputs the property distribution evaluation data obtained by the evaluation unit as two-dimensional data.

[0011] This porous membrane property evaluation device makes it easy to understand the evaluation results of at least one of the following: the pressure loss distribution and the film thickness distribution of the porous membrane.

[0012] The porous film property evaluation apparatus relating to the fourth perspective is a porous film property evaluation apparatus relating to the first, third, or any of the third perspectives, wherein the optical data is characteristic data of the reflected and scattered light obtained when light irradiated onto the porous film is reflected and scattered by the porous film.

[0013] This porous film property evaluation device uses reflected and scattered light to evaluate at least one of the pressure loss and film thickness of the porous film, making it easy to reflect the structure of the porous film in the optical data.

[0014] The porous film property evaluation apparatus relating to the fifth aspect is the porous film property evaluation apparatus relating to the fourth aspect, and the optical data includes an index relating to the brightness of reflected and scattered light. The index relating to brightness includes at least one of luminance, illuminance, luminous intensity, and brightness.

[0015] The apparatus for evaluating the physical properties of a porous film according to the sixth perspective is an apparatus for evaluating the physical properties of a porous film according to the fourth or fifth perspective, further comprising a light source and a reflection suppression sheet. The light source irradiates the porous film with light. The reflection suppression sheet is provided on the side of the porous film opposite to the side where the light source is located.

[0016] This porous film property evaluation device suppresses the influence of reflected and scattered light from objects located on the opposite side of the porous film from the light source on the optical data.

[0017] The apparatus for evaluating the physical properties of a porous membrane according to the seventh perspective is an apparatus for evaluating the physical properties of a porous membrane according to any of the first to sixth perspectives, wherein the porous membrane includes fibers.

[0018] This porous membrane property evaluation device makes it possible to evaluate at least one of the pressure loss or film thickness of porous membranes, even those with complex structures including fibers.

[0019] The porous membrane property evaluation apparatus relating to the eighth perspective is a porous membrane property evaluation apparatus relating to any of the first to seventh perspectives, wherein the porous membrane is a stretched porous membrane.

[0020] This porous membrane property evaluation device makes it possible to evaluate at least one of the pressure loss and film thickness of a porous membrane, even in stretched porous membranes, where it is difficult to ensure uniformity of stretching, which tends to cause variations in pressure loss or film thickness in certain areas of the stretched porous membrane.

[0021] The apparatus for evaluating the physical properties of a porous membrane according to the ninth perspective is an apparatus for evaluating the physical properties of a porous membrane according to any of the first to eighth perspectives, and the porous membrane is included in the filter material of an air filter.

[0022] This physical property evaluation apparatus for the porous membrane can evaluate at least one of the pressure loss and the membrane thickness of the porous membrane used as an air filter medium.

[0023] The physical property evaluation apparatus for the porous membrane according to the tenth aspect is the physical property evaluation apparatus for the porous membrane of the ninth aspect, wherein the object of physical property evaluation is a porous membrane with a membrane thickness of 150 μm or less, or a porous membrane with a pressure loss of 200 Pa or less when air passes through in the membrane thickness direction at a flow rate of 5.3 cm / second.

[0024] This physical property evaluation apparatus for the porous membrane can improve the evaluation accuracy of at least one of the pressure loss and the membrane thickness of the porous membrane.

[0025] The physical property evaluation apparatus for the porous membrane according to the eleventh aspect is the physical property evaluation apparatus for the porous membrane of the ninth or tenth aspect, and the evaluation unit has at least one of the following evaluation algorithms from 1 to 3. As the first evaluation algorithm, the evaluation of the pressure loss of the porous membrane based on the optical data of the porous membrane is performed for each of a plurality of predetermined ranges in the porous membrane. As the second evaluation algorithm, an evaluation algorithm for evaluating the physical properties of the porous membrane based on the optical data of one porous membrane or a laminate of a plurality of porous membranes, with the object of physical property evaluation, is different for each number of laminated porous membranes. As the third evaluation algorithm, an evaluation algorithm for evaluating the pressure loss for each of a plurality of predetermined ranges of the porous membrane based on the optical data of one porous membrane or a laminate of a plurality of porous membranes, with the object of physical property evaluation, is different for each number of laminated porous membranes. The pressure loss is the pressure loss when air passes through the porous membrane in the membrane thickness direction at a flow rate of 5.3 cm / second.

[0026] This physical property evaluation apparatus for the porous membrane can improve the evaluation accuracy of the physical properties of the porous membrane.

[0027] The physical property evaluation device for a porous membrane according to the 12th aspect is a physical property evaluation device for a porous membrane according to any one of the 1st to 9th aspects. The evaluation unit obtains physical property evaluation data for an evaluation target site by associating it with site correspondence data, based on the optical data of a predetermined evaluation target site when viewing the porous membrane from the membrane thickness direction of the porous membrane and the site correspondence data indicating the evaluation target site associated with the optical data.

[0028] This physical property evaluation device for a porous membrane enables grasping of evaluation data on physical properties corresponding to the evaluation target site of the porous membrane.

[0029] The physical property evaluation method for a porous membrane according to the 13th aspect evaluates at least one of the physical properties of the pressure loss and the membrane thickness of the porous membrane based on the optical characteristics of the porous membrane.

[0030] This physical property evaluation method for a porous membrane enables evaluation of the physical properties of the porous membrane without using a measuring device that measures the physical properties themselves because it evaluates the physical properties using the relationship between the optical data of the porous membrane and the physical properties of the porous membrane.

[0031] The method for manufacturing an air filter medium according to the 14th aspect obtains an evaluation result for an evaluation target site in a porous membrane by the physical property evaluation method for a porous membrane described in the 13th aspect, and manufactures an air filter medium including the porous membrane including the evaluation target site when the obtained evaluation result satisfies a predetermined condition.

[0032] This method for manufacturing an air filter medium enables obtaining an air filter medium including a porous membrane whose evaluation result satisfies a predetermined condition.

[0033] The porous film manufacturing apparatus relating to the 15th aspect comprises a porous film creation unit, an acquisition unit, and an evaluation unit. The porous film creation unit creates a porous film according to predetermined manufacturing conditions. The acquisition unit acquires two-dimensional optical data of the porous film created by the porous film creation unit. Based on the two-dimensional optical data of the porous film, the evaluation unit obtains distribution evaluation data for at least one of the physical property distributions in the porous film, namely the pressure loss distribution and the film thickness distribution, when the porous film is viewed from the film thickness direction of the porous film. The porous film creation unit updates the content of the predetermined manufacturing conditions based on the distribution evaluation data.

[0034] This porous membrane manufacturing apparatus makes it possible to obtain porous membranes with good physical property distribution by updating the predetermined manufacturing conditions of the porous membrane based on porous membrane distribution evaluation data.

[0035] The porous film manufacturing apparatus according to the 16th aspect is the porous film manufacturing apparatus according to the 15th aspect, wherein the porous film creation unit creates a porous film by stretching the object to be stretched. The predetermined manufacturing conditions include the stretching conditions for the object to be stretched.

[0036] This porous membrane manufacturing apparatus makes it possible to evaluate the distribution of physical properties in materials that are prone to variations in property distribution during stretching, such as stretched porous membranes.

[0037] The porous film manufacturing apparatus according to the 17th aspect is the porous film manufacturing apparatus according to the 16th aspect, wherein the stretching conditions of the object to be stretched include at least one of the stretching ratio, stretching temperature, and stretching speed.

[0038] This porous film manufacturing apparatus makes it possible to obtain porous films with reduced variability in physical property distribution by updating at least one of the conditions: the stretching ratio, stretching temperature, and stretching speed. [Brief explanation of the drawing]

[0039] [Figure 1] This is a functional block diagram of the manufacturing property evaluation system. [Figure 2] This is a schematic diagram of the apparatus used for stretching the porous membrane in the longitudinal direction. [Figure 3] This diagram schematically shows the apparatus for stretching a porous membrane in the width direction, laminating a breathable support material, and adjusting tension using an accumulator. [Figure 4] This is a flowchart showing the material property evaluation process. [Figure 5] This figure shows combined image data, a heatmap of brightness values, and a heatmap of measured pressure loss values. [Figure 6] This graph shows the calibration curve (part 1) for brightness values ​​and pressure loss. [Figure 7] This graph shows the calibration curve (part 2) for brightness values ​​and pressure loss. [Figure 8] This graph shows the relationship between brightness values ​​and film thickness for filter media types A through F. [Figure 9] This graph shows the relationship between luminance values ​​and film thickness for filter media types A to F (magnified view of filter media types A to D). [Figure 10] This graph shows the relationship between luminance values ​​and pressure loss for filter media types A through F. [Figure 11] This graph shows the calibration curves for filter media types B, C, and D. [Figure 12] This graph shows the relationship between the brightness value and film thickness of a porous polyethylene film. [Figure 13] This graph shows the relationship between the brightness value and pressure loss of a porous polyethylene membrane. [Modes for carrying out the invention]

[0040] The following describes a porous membrane property evaluation apparatus, a porous membrane property evaluation method, a porous membrane manufacturing apparatus, and an air filter material manufacturing method, using one embodiment as an example.

[0041] (1) Porous membrane Porous membranes include porous membranes with fibers and porous membranes without fibers, such as silica gel and activated carbon, but porous membranes with fibers are preferred. The porous membrane may be a single membrane or a laminate of two or more porous membranes stacked together.

[0042] Examples of porous membranes containing fibers include porous membranes obtained by generating fibers through stretching, and porous membranes obtained by methods such as electrospinning.

[0043] The material for the porous membrane obtained by generating fibers through stretching is not particularly limited and may include, for example, one or more selected from the group consisting of polytetrafluoroethylene (PTFE), nylon such as nylon 6, polypropylene, ultra-high molecular weight polyethylene (UHMW-PE), polyethylene, polystyrene, polyester, polyphenylene sulfide, polyethylene oxide, polymethyl methacrylate, cellulose acetate, polycarbonate, polyvinyl chloride, polyetherimide, polyvinyl alcohol, polyethylene terephthalate, polyacrylonitrile, polyvinylidene fluoride, polystyrene, polyurethane, polyimide, polylactic acid, and polycaprolactone. The ultra-high molecular weight polyethylene may have a melting point of 135°C to 140°C as measured in accordance with ATMS D 3418. The weight-average molecular weight of the ultra-high molecular weight polyethylene is, for example, 1 million or more, and preferably 1.5 million or more. Polyethylene may be defined as having a melting point of 100°C or higher and 130°C or lower, as measured in accordance with ATMM D 3418.

[0044] Furthermore, the porous membrane obtained by generating fibers by the electrospinning method may be, for example, a porous membrane having nanofibers. Examples of nanofiber materials include polyester and polyamide.

[0045] Furthermore, the above-mentioned porous membranes are preferably used in air filter media. The air filter media preferably has a porous membrane laminated with a permeable support layer. The permeable support layer may be provided on one or both sides of the porous membrane in the air passage direction. The permeable support layer may have a pressure loss lower than that of the porous membrane when air is passed through it at a flow velocity of 5.3 cm / second in the film thickness direction. The pressure loss of the permeable support layer is preferably, for example, 10 Pa or less, more preferably 5 Pa or less, and even more preferably 1 Pa or less. The thickness of the permeable support layer is preferably, for example, 500 μm or less, and more preferably 300 μm or less.

[0046] Furthermore, for porous films whose physical properties are evaluated based on optical property data, it is preferable that the porous film has a film thickness of 150 μm or less, or a pressure loss of 200 Pa or less when air is passed through it in the direction of film thickness at a flow velocity of 5.3 cm / sec, from the viewpoint of increasing the reliability of the evaluation. In particular, it is more preferable that the porous film to be evaluated has a film thickness of 100 μm or less, and even more preferable that it has a film thickness of 50 μm or less. The lower limit of the film thickness of the porous film to be evaluated can be, for example, 1 μm, or it may be 10 μm. Furthermore, it is preferable that the porous film to be evaluated has a pressure loss of 175 Pa or less. Furthermore, the lower limit of the pressure loss of the porous film to be evaluated can be, for example, 50 Pa, and it is preferable that it is 100 Pa or more.

[0047] Furthermore, if the porous membrane contains fibers, the average fiber diameter may be, for example, 0.05 μm or more and 0.25 μm or less, and preferably 0.1 μm or more and 0.20 μm or less. Here, the average fiber diameter is determined as follows: First, the surface of the test sample is photographed with a scanning electron microscope (SEM) at 1000 to 5000x magnification, and two orthogonal lines are drawn on one of the captured images. The thickness of the image of the fiber that intersects these lines is obtained as the fiber diameter. Here, the number of fibers to be measured should be 200 or more. The fiber diameters thus obtained are plotted on a log-normal scale with the fiber diameter on the x-axis and the cumulative frequency on the y-axis, and the value at which the cumulative frequency reaches 50% is taken as the average fiber diameter.

[0048] (2) Physical properties of the porous film to be evaluated The physical properties of the porous membrane to be evaluated include either the pressure drop of the porous membrane, the thickness of the porous membrane, or both.

[0049] The pressure loss of the porous membrane being evaluated is the pressure loss when air is passed through the porous membrane in the direction of its thickness at a flow velocity of 5.3 cm / second.

[0050] The thickness of the porous film to be evaluated is the thickness in the thickness direction of the porous film. The thickness of the porous film to be evaluated may be the value obtained by dividing the total thickness measured when multiple porous films are stacked and a load of 0.3 N is applied in the thickness direction by the number of stacked films. When evaluating the thickness of a stack of multiple porous films, the thickness in the thickness direction of the stack will be evaluated.

[0051] (3) Two-dimensional optical property data of porous films The two-dimensional optical property data of a porous film is not particularly limited and includes, for example, image data of the porous film and data showing the distribution of the optical properties of the porous film.

[0052] The optical properties of a porous film can be defined by the characteristics of the reflected and scattered light obtained when light irradiated onto the porous film is reflected and scattered by the film. Even if the porous film has a complex shape or structure, this complex shape or structure will affect the reflected and scattered light. Therefore, since the physical properties of the porous film can be evaluated using optical properties that reflect the shape and structure of the porous film, a highly reliable evaluation that reflects the shape and structure of the porous film becomes possible.

[0053] The characteristics of reflected and scattered light from a porous film can be assessed using indicators related to the brightness of the porous film, such as values ​​obtained by a predetermined relational expression that combines at least one of luminance, illuminance, luminous intensity, or brightness, or at least one of these factors. In evaluating the physical properties of a porous film, the properties can be assessed according to the magnitude of the values ​​shown as optical properties of the porous film. For example, a higher luminance of a porous film indicates a greater pressure loss, and a higher luminance of a porous film indicates a greater film thickness.

[0054] (4) Porous membrane management system The following description will use a porous membrane management system 100 equipped with a physical property evaluation device 50 according to one embodiment as an example. In this description, the example will be the manufacturing of an air filter filter material 30, which is a filter material equipped with a porous membrane 31.

[0055] As shown in Figure 1, the porous membrane management system 100 includes a filter material manufacturing device 40, a physical property evaluation device 50, an imaging device 70, and a labeler 80.

[0056] The filter media manufacturing apparatus 40, the physical property evaluation apparatus 50, the imaging apparatus 70, and the labeler 80 are connected to each other via a communication network such as a local area network, enabling them to communicate with one another.

[0057] (5) Filter media manufacturing equipment The filter media manufacturing apparatus 40 is an apparatus for manufacturing air filter media 30, which is a filter media containing a porous membrane 31 obtained by generating fibers through stretching, and comprises a first manufacturing apparatus 40a shown in Figure 2 and a second manufacturing apparatus 40b shown in Figure 3.

[0058] For example, if the porous membrane is a fluororesin porous membrane such as a PTFE porous membrane obtained by stretching polytetrafluoroethylene to generate fibers, it can be manufactured using the first manufacturing apparatus 40a and the second manufacturing apparatus 40b in the following manner.

[0059] First, a sheet-like extruded material is obtained by dewatering and drying a fine powder obtained from the emulsion polymerization of tetrafluoroethylene (TFE) through coagulation and co-coagulation, followed by paste extrusion. The sheet-like extruded material is then rolled using a calender roll or the like to obtain an unbaked film. A porous fluororesin film is obtained by removing the liquid lubricant from the unbaked film and stretching it. Stretching of the unbaked film is performed, for example, by stretching it longitudinally along the longitudinal direction (conveying direction) using a first manufacturing apparatus 40a, followed by stretching it in the width direction perpendicular to the longitudinal direction (conveying direction) using a second manufacturing apparatus 40b. Stretching generates fluororesin fibers, resulting in a porous fluororesin film containing these fibers.

[0060] As shown in Figure 2, the first manufacturing apparatus 40a is equipped with an unwinding roll 1, a winding roll 2, rolls 3-5, heat rolls 6, 7, and rolls 8-12. This first manufacturing apparatus 40a produces rolls of stretched sheets in which the unbaked film is stretched in the longitudinal direction (conveying direction).

[0061] As shown in Figure 3, the second manufacturing apparatus 40b includes an unwinding roll 14, a roll 15, a stretching furnace 16, a roll 17, a reflection suppression sheet 18, a light source 19, breathable support materials 21 and 22 which are breathable support layers, laminate rolls 23 and 24, an accumulator 25, a trimmer 26, a roll 27, and a winding roll 29. The second manufacturing apparatus 40b further stretches the sheet obtained by the first manufacturing apparatus 40a in the width direction (a direction intersecting both the conveying direction and the thickness direction) to obtain a porous membrane, and then manufactures a filter material by sandwiching the porous membrane between the breathable support materials 21 and 22.

[0062] The filter media manufacturing apparatus 40, which includes a first manufacturing apparatus 40a and a second manufacturing apparatus 40b, comprises a processor 41 such as a CPU (Central Processing Unit) that performs various information processing, a memory 45 configured with RAM (Random Access Memory) and ROM (read-only memory), a display 42 for displaying and outputting setting information and driving status, a reception unit 43 for receiving input of various manufacturing condition information, a group of adjustment units 44, and a transmitting / receiving unit 49.

[0063] The adjustment unit group 44 includes an adjustment unit for adjusting the unwinding speed of the unwinding roll 14, an adjustment unit for adjusting the transport speed of the roll 15, an adjustment unit for adjusting the widthwise stretching conditions in the stretching furnace 16, an adjustment unit for adjusting the temperature inside the furnace, an adjustment unit for adjusting the transport speed of the roll 17, an adjustment unit for ON / OFF control of the light source 19, an adjustment unit for adjusting the heating temperature of the laminating rolls 23 and 24, an adjustment unit for adjusting the transport speed of the laminating rolls 23 and 24, an adjustment unit for adjusting the tension applied in the accumulator 25, an adjustment unit for adjusting the cut width in the trimmer 26, an adjustment unit for adjusting the transport speed of the roll 27, an adjustment unit for adjusting the winding speed of the winding roll 29, and the like. In the case where the stretching furnace 16 is provided with a heater on the left side and a heater on the right side in the view of the transport direction of the porous film, and the heating temperature of each can be controlled, the stretching conditions may include the heating temperature conditions of each heater.

[0064] The memory 45 stores information necessary for control, such as transport control data 45a used to control the unwinding speed and transport speed of each roll, tension control data 45b used to adjust the tension applied by the accumulator 25, stretch control data 45c related to stretching conditions used for stretching control, including the stretching ratio, stretching speed, and stretching temperature in the longitudinal direction of the first manufacturing apparatus 40a, and the stretching ratio, stretching speed, and stretching temperature in the width direction of the second manufacturing apparatus 40b, and programs used for various controls.

[0065] The transmitting / receiving unit 49 is a communication interface for connecting the filter media manufacturing apparatus 40, the imaging device 70, the labeler 80, and the physical property evaluation device 50 so that they can communicate via a communication network. The filter media manufacturing apparatus 40 receives physical property evaluation data 54f and corresponding part-corresponding data 54c from the physical property evaluation device 50 via the transmitting / receiving unit 49, and transmits transport control data 45a and tension control data 45b to the labeler 80, etc.

[0066] Furthermore, the processor 41 updates the information stored in memory 45, such as the transport control data 45a, tension control data 45b, and stretch control data 45c, based on the physical property evaluation data 54f and corresponding part-corresponding data 54c (physical property evaluation data 45d and corresponding part-corresponding data 45e stored in memory 45) sent from the physical property evaluation device 50 described later, and overwrites the data in memory 45. For example, if the physical property evaluation data 45d for a certain part does not meet a predetermined condition, the transport control data 45a, tension control data 45b, stretch control data 45c, etc. are updated. For example, if the physical property evaluation data 45d is an evaluation of pressure loss, and the pressure loss is higher than a predetermined condition value, the stretching ratio in the vertical direction or the stretching ratio in the width direction may be increased by a predetermined value, the stretching speed in the vertical direction or the stretching speed in the width direction may be decreased by a predetermined value, the stretching temperature in the vertical direction or the stretching temperature in the width direction may be increased by a predetermined value, or a combination of these changes may be used. Furthermore, for example, if the physical property evaluation data 45d is an evaluation of film thickness, and the film thickness is greater than a predetermined condition value, the stretching ratio in the longitudinal direction or the stretching ratio in the width direction may be increased by a predetermined value, the stretching speed in the longitudinal direction or the stretching speed in the width direction may be increased by a predetermined value, the stretching temperature in the longitudinal direction or the stretching temperature in the width direction may be increased by a predetermined value, or a combination of these changes may be made.

[0067] In the first manufacturing apparatus 40a, the processor 41 reads and executes information such as stretching control data 45c stored in the memory 45, thereby adjusting the transport speed of the unwinding roll 1, winding roll 2, rolls 3-5, heat rolls 6 and 7, and rolls 8-12, and adjusting the heating temperature of the heat rolls 6 and 7, thereby obtaining a roll of stretched sheet with controlled stretching in the longitudinal direction (transport direction).

[0068] In the second manufacturing apparatus 40b, the processor 41 reads and executes information such as transport control data 45a, tension control data 45b, and stretching control data 45c stored in the memory 45, thereby adjusting the transport speed, unwinding speed, and winding speed of the unwinding roll 14, roll 15, roll 17, laminating rolls 23, 24, accumulator 25, roll 27, and winding roll 29, and adjusting the heating temperature in the stretching furnace 16, thereby obtaining a porous film sheet with controlled stretching in the width direction (a direction intersecting both the transport direction and the thickness direction). When manufacturing with the second manufacturing apparatus 40b, the processor 41 turns on the light source 19. Also, when manufacturing with the second manufacturing apparatus 40b, the processor 41 reads and executes information stored in the memory 45 to adjust the cut width in the trimmer 26, thereby obtaining a porous film sheet with adjusted cut width.

[0069] Specifically, the stretched sheet fed from the unwinding roll 14 is conveyed by the roll 15 and sent to the stretching furnace 16. In the stretching furnace 16, the stretched sheet is heated and stretched in the width direction perpendicular to the longitudinal direction, which is the conveying direction, to obtain a porous film 31. The obtained porous film 31 is conveyed by the roll 17, passes through the imaging area of ​​the imaging device 70, and is sent to the laminating rolls 23 and 24 for laminating the breathable support materials 21 and 22. Because the porous film 31 obtained by stretching has a fine fiber diameter, is thin and soft, the breathable support materials 21 and 22 are laminated onto the porous film 31.

[0070] When laminating the breathable support materials 21 and 22 onto the porous membrane 31, the breathable support materials 21 and 22, made of nonwoven fabric, are laminated on both sides of the porous membrane 31 and then heat-laminate them by passing them between laminating rolls 23 and 24 to bond them together. Here, the processor 41 adjusts the temperature of the laminating rolls 23 and 24 as the material passes through them, ensuring that enough heat is transferred to melt the materials of the breathable support materials 21 and 22, while also adjusting the transport speed to prevent overheating.

[0071] The user can input settings such as the transport speed and the degree of tension applied in the accumulator 25, according to the filter media to be manufactured, via the reception unit 43 of the filter media manufacturing apparatus 40. For example, in order to obtain an air filter media 30 that is uniformly spread by the application of tension, the processor 41 changes the height between the rolls in the accumulator 25 so that tension is applied according to the physical properties of the permeable support material 21, 22 and the porous membrane 31. Specifically, the greater the height between the rolls in the accumulator 25, the greater the tension applied to the air filter media 30, and the longer the length of the air filter media 30 in the transport direction. The data received by the reception unit 43 is stored in the memory 45 as transport control data 45a and tension control data 45b. The filter media manufacturing apparatus 40 then transmits the transport control data 45a and tension control data 45b stored in the memory 45 to the labeler 80. Subsequently, the air filter media 30 of a predetermined width is obtained by trimming both ends in the width direction of the filter media with the trimmer 26.

[0072] The labeler 80 is a device for attaching labels 80x, on which the physical property evaluation data 54f described later is printed, to the area to be evaluated. The labeler 80 includes a processor 81 such as a CPU for performing various information processing, a memory 82 configured with RAM and ROM, a printing processing unit 83 for printing on labels, an attachment processing unit 84 for attaching labels, and a transmitting and receiving unit 85 for sending and receiving data. The memory 82 stores the physical property evaluation data 54f and the corresponding area-specific data 54c transmitted from the physical property evaluation device 50 as physical property evaluation data 82a and the corresponding area-specific data 82b. The memory 82 also stores information regarding the distance between the imaging position, which is the position where imaging is performed by the imaging device 70, and the accumulator 25, as well as information regarding the distance from the accumulator 25 to the labeler 80.

[0073] The transmitting / receiving unit 85 is a communication interface for connecting the labeler 80, the filter media manufacturing apparatus 40, the imaging device 70, and the physical property evaluation apparatus 50 so that they can communicate via a communication network. The labeler 80 receives transport control data 45a and tension control data 45b from the filter media manufacturing apparatus 40, and physical property evaluation data 54f and corresponding part-specific data 54c from the physical property evaluation apparatus 50 via the transmitting / receiving unit 85.

[0074] In the labeler 80, the processor 81 stores the physical property evaluation data 54f and corresponding part correspondence data 54c transmitted from the physical property evaluation device 50 in the memory 82 as physical property evaluation data 82a and corresponding part correspondence data 82b. If there is any physical property evaluation data 82a that does not meet predetermined physical property conditions and corresponding part correspondence data 82b, the processor 81 has the printing processing unit 83 print the physical property evaluation data 82a that does not meet the predetermined physical property conditions to create a label 80x. Then, in the labeler 80, the processor 81 has the application processing unit 84 apply the created label 80x to the physical property evaluation position on the air filter filter material 30 that is determined by the part correspondence data 82b corresponding to the physical property evaluation data 54f that does not meet the predetermined physical property conditions. Here, the processor 81 uses the transport control data 45a and tension control data 45b transmitted from the filter media manufacturing apparatus 40, the part corresponding data 54c indicating the imaging position by the imaging device 70 stored in the memory 82, and the distance information between the accumulator 25 and the labeler 80 to calculate the time required for the portion corresponding to the physical property evaluation data 54f that does not meet the predetermined physical property conditions to be transported to the position of the labeler 80. As a result, even if the length of the air filter media 30 in the transport direction changes due to the tension applied by the accumulator 25, the label 80x indicating the physical property evaluation data 54f that does not meet the predetermined physical property conditions can be appropriately attached to the corresponding physical property evaluation area by the attachment processing unit 84.

[0075] Subsequently, in the winding process, the air filter media 30 is wound onto the winding roll 29.

[0076] The imaging device 70 is a device that images a predetermined area of ​​a porous membrane and includes a camera 71 which is an area sensor camera, a processor 72, a transmitting / receiving unit 73, a memory 74, and the like.

[0077] The transmitting / receiving unit 73 is a communication interface for connecting the imaging device 70, the filter media manufacturing device 40, the physical property evaluation device 50, and the labeler 80 so that they can communicate via a communication network. The imaging device 70 transmits image data 74a and corresponding part-corresponding data 74b to the physical property evaluation device 50 via the transmitting / receiving unit 73.

[0078] The imaging device 70 repeatedly takes images of the transported porous membrane 31 from a fixed position, changing the imaging area at predetermined time intervals, and continuously stores each obtained image data 74a in memory 74, associating it with area-corresponding data 74b indicating the imaging position on the porous membrane. The imaging device 70 also continuously transmits the stored image data 74a and the corresponding area-corresponding data 74b to the physical property evaluation device 50 via the transmitting / receiving unit 73. In this embodiment, instead of using a line camera 71 that captures scattered light from the porous membrane on a predetermined line in a direction intersecting the transport direction of the porous membrane, an area camera is used that images a region having a predetermined width in both the transport direction of the porous membrane and the direction intersecting that direction. This makes it possible to perform physical property evaluation of the porous membrane quickly and accurately, and facilitates real-time evaluation processing of the porous membrane. Furthermore, for porous membranes and filter materials wound into a roll, it becomes possible to grasp the physical properties of the entire porous membrane or filter material, rather than measuring the physical properties only at the ends in the transport direction. Therefore, it is possible to avoid evaluating the entire roll based only on the physical property measurements of the ends in the conveying direction.

[0079] At the imaging location of the imaging device 70, multiple light sources 19 are provided to illuminate the imaging area of ​​the porous film 31 from the same side as the imaging device 70 is located on the porous film 31. From the viewpoint of reducing brightness unevenness of the porous film 31, it is preferable that the multiple light sources 19 are arranged to illuminate in different directions from each other when viewed in the thickness direction of the porous film 31, and more preferably, they are arranged to illuminate in opposing directions. This makes it possible to more appropriately determine the brightness value of the porous film 31, whether the porous film 31 is light-transmitting or light-reflecting. In addition, at the imaging location of the imaging device 70, the reflection suppression sheet 18 is located on the side opposite to the side of the porous film 31 from where the imaging device 70 and light sources 19 are located. The reflection suppression sheet 18 is provided so as to spread substantially parallel to the surface of the porous film 31. It is preferable that the reflection suppression sheet 18 is a color that is complementary to the color of the porous film 31. When photographing porous films that appear white due to light reflection and scattering, such as fluororesin porous films, it is preferable to use a black sheet with suppressed light reflection as the reflection suppression sheet 18, and more preferably to use a non-reflective material such as a known non-reflective flocked cloth. This makes it easier to understand the brightness distribution from the image data 74a of the porous film 31. The light emitted from the light source 19 may have a wavelength longer than the average fiber diameter of the porous film, for example, and may include visible light.

[0080] The physical property evaluation device 50 is a device that evaluates the physical properties of a porous film based on the optical property data of the porous film, and includes a processor 51 such as a CPU or GPU (Graphics Processing Unit) that performs various information processing, a display 52, a transmitting and receiving unit 53, and memory 54 such as RAM or ROM.

[0081] The transmitting / receiving unit 53 is a communication interface for connecting the physical property evaluation device 50, the filter media manufacturing device 40, the labeler 80, and the imaging device 70 so that they can communicate via a communication network. The physical property evaluation device 50 transmits physical property evaluation data 54f and corresponding part-corresponding data 54c to the filter media manufacturing device 40 and the labeler 80 via the transmitting / receiving unit 53, and receives image data 74a and corresponding part-corresponding data 74b transmitted from the imaging device 70.

[0082] Memory 54 stores optical data, including image data 54a, optical property data 54b, part-specific data 54c, an optical property extraction program 54d, a physical property evaluation model 54e for evaluating the physical properties of a porous film, physical property evaluation data 54f, and distribution evaluation data 54g. Memory 54 stores the image data 74a and its corresponding part-specific data 74b received by the transmitting / receiving unit 53 as image data 54a and its corresponding part-specific data 54c, while maintaining the correspondence between the two sets of data. In this embodiment, image data 54a is two-dimensional data and is two-dimensional optical data.

[0083] The optical characteristic extraction program 54d is a program used by the processor 51 to extract optical characteristic data 54b associated with the region-corresponding data 54c from the image data 74a (image data 54a) associated with the region-corresponding data 54c transmitted from the imaging device 70, and to store it in the memory 54.

[0084] The optical property data 54b is optical data, which is two-dimensional optical data showing the distribution of optical properties in the porous film 31 when the porous film 31 is viewed from the film thickness direction. For example, it may be two-dimensional optical property data such as a heat map that represents the difference in optical property values ​​in each part of the porous film 31 by the difference in color or the intensity of the color, or it may be two-dimensional optical property data that shows the optical property values ​​for each part of the porous film 31. Preferably, the two-dimensional optical property data is data that extends in the vertical direction, which is the transport direction of the porous film 31, and in the width direction perpendicular to the vertical direction. Such optical property data 54b can be, for example, data showing the distribution of brightness for each pixel in the image data 54a, or data showing the distribution of average brightness when a region of multiple pixels in the image data 54a is treated as a single unit.

[0085] The physical property evaluation model 54e includes at least one of the following: an algorithm for evaluating the pressure loss of the porous film 31 based on the optical property data 54b of the porous film 31, and an algorithm for evaluating the film thickness of the porous film 31.

[0086] In evaluating pressure loss, the pressure loss is evaluated using either a single pixel region of the original image data 54a in the optical characteristic data 54b as one evaluation unit (predetermined range), or a region of multiple pixels in the original image data 54a as one evaluation unit (predetermined range). Specifically, for example, the pressure loss value at a pixel is evaluated based on the brightness value of the region corresponding to a single pixel in the original image data 54a, or the pressure loss value at a region of multiple pixels is evaluated based on the average value of the brightness values ​​of the regions corresponding to multiple pixels in the original image data 54a. Furthermore, in evaluating the pressure loss, instead of using the brightness of one pixel or the average value of the brightness of multiple pixels in the original image data 54a in the optical characteristic data 54b, the illuminance, luminosity, brightness, etc., obtained for each region of a predetermined size in the optical characteristic data 54b may be used, or the illuminance of one pixel or the average value of the illuminance of multiple pixels in the optical characteristic data 54b may be used, or the luminosity of one pixel or the average value of the luminosity of multiple pixels in the original image data 54a in the optical characteristic data 54b may be used, or the brightness of one pixel or the average value of the brightness of multiple pixels in the original image data 54a in the optical characteristic data 54b may be used. Then, the pressure loss evaluation for each of the above evaluation units is performed for the entire region of the porous membrane 31.

[0087] Here, the physical property evaluation model 54e used to evaluate pressure loss is preferably an algorithm in which the pressure loss is evaluated as higher the value of brightness-related indicators such as luminance, illuminance, luminous intensity, and brightness. For example, in areas of the porous membrane 31 where fibers are partially clustered, the luminance tends to be locally high, and the pressure loss tends to be high. In this physical property evaluation model 54e, it is preferable that multiple algorithms are provided as algorithms for evaluating pressure loss, depending on the type of porous membrane 31 manufactured by the filter media manufacturing apparatus 40. The type of porous membrane 31 may be a type corresponding to the degree of pressure loss of the porous membrane 31, or if the porous membrane 31 is a laminate of one or more porous membranes, it may be a type corresponding to the number of laminated porous membranes, or it may be a type corresponding to the degree of collection efficiency of the porous membrane 31, or it may be a type determined by a combination of these. For example, if the approximate pressure loss of the porous membrane 31 manufactured by the filter media manufacturing apparatus 40 can be determined, it is preferable that the physical property evaluation model 54e has multiple types of algorithms corresponding to the approximate pressure loss, and more preferably multiple types of algorithms for each numerical range of pressure loss, so that the pressure loss can be evaluated based on an algorithm corresponding to the approximate pressure loss. For example, different types of algorithms may be provided for each of several predetermined ranges where the difference between the upper and lower limits of the pressure loss is 20 Pa or more and 40 Pa or less, depending on the approximate pressure loss (for example, each predetermined range where the difference between the upper and lower limits is 30 Pa). In addition, different algorithms may be provided for when the approximate pressure loss is 130 Pa or more and less than 170 Pa, for when the approximate pressure loss is 170 Pa or more and less than 200 Pa, and for when the approximate pressure loss is 200 Pa or more and less than 240 Pa. This makes it possible to evaluate the pressure loss of the porous membrane according to the evaluation value of the pressure loss, and improves the evaluation accuracy.The approximate pressure loss of the porous membrane 31 may be determined, for example, based on the porous membrane material, the stretching ratio in the longitudinal direction, the stretching ratio in the width direction, the stretching speed in the longitudinal direction, the stretching speed in the transverse direction, the stretching temperature in the longitudinal direction, and the stretching temperature in the transverse direction. Specifically, for example, when manufacturing a porous membrane obtained by stretching a specific PTFE under specific conditions, an approximate pressure loss is determined based on the type of PTFE and the stretching conditions. Then, the pressure loss can be evaluated using an algorithm corresponding to the range of pressure loss to which the obtained approximate pressure loss belongs. In this case, the physical property evaluation device 50 may receive stretching control data 45c from the filter media manufacturing device 40, and the processor 51 may select and use a specific algorithm from among multiple algorithms of the physical property evaluation model 54e based on the stretching control data 45c.

[0088] In evaluating film thickness, the area of ​​one pixel in the original image data 54a in the optical characteristic data 54b is used as one evaluation unit (predetermined range), or the area of ​​multiple pixels in the original image data 54a is used as one evaluation unit (predetermined range) to evaluate the corresponding film thickness. Specifically, for example, the film thickness value at the location of a pixel is evaluated based on the brightness value of the area corresponding to one pixel in the original image data 54a, or the film thickness value at the location of multiple pixels is evaluated based on the average value of the brightness values ​​of the areas corresponding to multiple pixels in the original image data 54a. Furthermore, in evaluating the film thickness, instead of using the brightness of one pixel or the average value of the brightness of multiple pixels in the original image data 54a in the optical characteristic data 54b, the illuminance, luminosity, brightness, etc., obtained for each region of a predetermined size in the optical characteristic data 54b may be used, or the illuminance of one pixel or the average value of the illuminance of multiple pixels in the original image data 54a in the optical characteristic data 54b may be used, or the luminosity of one pixel or the average value of the luminosity of multiple pixels in the original image data 54a in the optical characteristic data 54b may be used, or the brightness of one pixel or the average value of the brightness of multiple pixels in the original image data 54a in the optical characteristic data 54b may be used.Then, the film thickness evaluation for each of the above evaluation units is performed for the entire region of the porous film 31.

[0089] Here, the physical property evaluation model 54e used to evaluate film thickness is preferably an algorithm in which the higher the value of brightness-related indicators such as luminance, illuminance, luminous intensity, and brightness, the higher the film thickness is evaluated. For example, in areas of the porous membrane 31 where fibers are partially clustered, the luminance tends to be locally high, and the film thickness tends to be high. As this physical property evaluation model 54e, it is preferable that multiple algorithms are provided for evaluating film thickness, depending on the type of porous membrane 31 manufactured by the filter material manufacturing apparatus 40. The type of porous membrane 31 may be a type corresponding to the degree of film thickness of the porous membrane 31, or if the porous membrane 31 is a laminate of one or more porous membranes, it may be a type corresponding to the number of laminated porous membranes, or it may be a type corresponding to the degree of collection efficiency of the porous membrane 31, or it may be a type determined by a combination of these. For example, if the approximate thickness of the porous membrane 31 manufactured by the filter media manufacturing apparatus 40 can be determined, it is preferable that the physical property evaluation model 54e has multiple types of algorithms corresponding to the approximate thickness, and more preferably multiple types of algorithms for each numerical range of the thickness, so that the thickness can be evaluated based on an algorithm corresponding to the approximate thickness. For example, different types of algorithms may be provided for each of several predetermined ranges where the difference between the upper and lower limits of the thickness is 5 μm or more and 15 μm or less, depending on the approximate thickness (for example, each predetermined range where the difference between the upper and lower limits is 10 μm). In addition, different algorithms may be provided for use when the approximate thickness is 1 μm or more and less than 10 μm, for use when the approximate thickness is 20 μm or more and less than 30 μm, and for use when the approximate thickness is 30 μm or more and less than 40 μm. This makes it possible to evaluate the thickness of the porous membrane according to the evaluation value of the thickness, and improves the evaluation accuracy. The approximate thickness of the porous film 31 may be determined, for example, based on the porous film material, the stretching ratio in the longitudinal direction, the stretching ratio in the width direction, the stretching speed in the longitudinal direction, the stretching speed in the transverse direction, the stretching temperature in the longitudinal direction, the stretching temperature in the transverse direction, etc.Specifically, for example, when manufacturing a porous film obtained by stretching a specific PTFE under specific conditions, an approximate value of the film thickness is determined according to the type of PTFE and the stretching conditions. Then, the film thickness can be evaluated using an algorithm corresponding to the range of film thickness to which the obtained approximate value belongs. In this case, the physical property evaluation device 50 receives stretching control data 45c from the filter material manufacturing device 40, and the processor 51 may select and use a specific algorithm from among multiple algorithms of the physical property evaluation model 54e based on the stretching control data 45c.

[0090] These evaluated pressure loss or film thickness values ​​are stored in memory 54 as physical property evaluation data 54f, associated with information identifying the evaluation target area in the porous film 31. Specifically, the pressure loss or film thickness values ​​evaluated based on the brightness values, etc., at the evaluation target area for each evaluation unit of the optical property data 54b used for physical property evaluation are associated with the data indicating the evaluation target area, and stored in memory 54 for each evaluation target area. Alternatively, both pressure loss and film thickness may be evaluated simultaneously and stored in memory 54.

[0091] The distribution evaluation data 54g is two-dimensional data showing the distribution of at least one of the physical properties of the porous membrane 31: pressure loss and film thickness. The processor 51 of the physical property evaluation device 50 creates the distribution evaluation data 54g, which is two-dimensional data showing the physical property distribution of the porous membrane 31, based on the physical property evaluation data 54f stored in the memory 54 and the site correspondence data 54c stored in correspondence with the physical property evaluation data 54f, and stores it in the memory 54.

[0092] The distribution evaluation data 54g is two-dimensional data showing the distribution of at least one of the physical properties of the porous membrane 31, namely pressure loss and film thickness, when the porous membrane 31 is viewed from the film thickness direction. For example, it may be two-dimensional data such as a heat map that represents the differences in the values ​​of the physical properties in each part of the porous membrane 31 by differences in color or shade of color, or it may be two-dimensional data that shows the values ​​of the physical properties for each part of the porous membrane 31. Preferably, such two-dimensional data extends in the vertical direction, which is the transport direction of the porous membrane 31, and in the width direction perpendicular to the vertical direction.

[0093] The physical property evaluation data 54f and the corresponding part-corresponding data 54c stored in the memory 54 are then transmitted to the filter media manufacturing apparatus 40 and the labeler 80 via the transmission / reception unit 53. The distribution evaluation data 54g is output to the display 52 by the processor 51. In this case, for example, as shown in Figure 5 below, the image data 54a, the optical property data 54b, and the distribution evaluation data 54g may be displayed side by side on the display 52 by the processor 51. This makes it possible to easily visualize the physical property distribution of the porous film 31.

[0094] In the above evaluation of the physical properties of the porous membrane, the evaluation is performed by information processing using image data 54a, so there is no need to perform processes such as measuring pressure loss using a measuring instrument (a process of pressing a circular cup or the like against the porous membrane and blowing air at 5.3 m / s during the actual measurement) or measuring film thickness using a measuring instrument (a process of applying a predetermined load during the actual measurement). Therefore, since it is possible to avoid damaging the porous membrane when understanding its physical properties, the physical property distribution of the porous membrane can be evaluated by non-destructive testing.

[0095] (6) Physical property evaluation process for porous films Below, we will explain an example of a physical property evaluation process, referring to the flowchart in Figure 4.

[0096] In step S11, the imaging device 70 transmits the image data 74a of the porous membrane 31 and the corresponding area-corresponding data 74b from the transmitting / receiving unit 73 to the physical property evaluation device 50 via the communication network. Here, the processor 72 of the imaging device 70 drives the camera 71 to acquire the image data 74a of the porous membrane 31, and at the same time acquires the area-corresponding data 74b indicating the area of ​​the porous membrane 31 from which the image data 74a was acquired, stores them in the memory 74, and transmits them from the transmitting / receiving unit 73 to the physical property evaluation device 50. Since the imaging device 70 repeatedly takes images from a fixed position while changing the imaging area at predetermined time intervals for the transported porous membrane 31, the area-corresponding data 74b may be, for example, data that is understood as the number of images taken, or data that is understood as the imaging time.

[0097] In step S12, the physical property evaluation device 50 obtains physical property evaluation data 54f based on the image data 74a transmitted from the imaging device 70 and the corresponding part-corresponding data 74b. Specifically, the processor 51 of the physical property evaluation device 50 receives the image data 74a and part-corresponding data 74b transmitted from the imaging device 70 in the transmitting / receiving unit 53 and stores them in the memory 54 as the image data 54a and the corresponding part-corresponding data 54c, respectively. Then, the processor 51 of the physical property evaluation device 50 reads the optical property extraction program 54d and creates optical property data 54b from the image data 54a. Furthermore, the processor 51 of the physical property evaluation device 50 obtains physical property evaluation data 54f based on optical properties such as brightness obtained from the optical property data 54b, according to the algorithm stored in the physical property evaluation model 54e. The processor 51 of the physical property evaluation device 50 stores the physical property evaluation data 54f and the corresponding part correspondence data 54c (image data 54a used to obtain the physical property evaluation data 54f) in the memory 54. Furthermore, the processor 51 of the physical property evaluation device 50 creates distribution evaluation data 54g based on the physical property evaluation data 54f and the part correspondence data 54c (stored in correspondence with the physical property evaluation data 54f), and stores it in the memory 54. The distribution evaluation data 54g is output to the display 52 by the processor 51.

[0098] In step S13, the processor 51 of the physical property evaluation device 50 transmits the physical property evaluation data 54f stored in the memory 54 and the corresponding part-corresponding data 54c to the filter material manufacturing device 40 and the labeler 80 via the transmitting and receiving unit 53.

[0099] In step S14, the processor 41 of the filter media manufacturing apparatus 40 receives the physical property evaluation data 54f and the corresponding part correspondence data 54c transmitted from the physical property evaluation device 50 at the transmitting / receiving unit 49, and stores them in the memory 45 as physical property evaluation data 45d and the corresponding part correspondence data 45e, respectively. The processor 41 of the filter media manufacturing apparatus 40 then determines whether the physical property evaluation data 45d contains any part that does not meet the predetermined physical property conditions for the evaluated physical properties. If it does not meet the conditions, it updates the manufacturing conditions corresponding to the part that does not meet the conditions and saves them in the memory 45.

[0100] In step S15, the processor 81 of the labeler 80 receives the physical property evaluation data 54f and the corresponding part correspondence data 54c transmitted from the physical property evaluation device 50 in the transmitting / receiving unit 85, and stores them in the memory 82 as physical property evaluation data 82a and the corresponding part correspondence data 82b, respectively. The processor 81 of the labeler 80 then determines whether the physical property evaluation data 45d includes any part that does not meet the predetermined physical property conditions for the evaluated physical properties, and if it does not, it attaches the part of the label 80x indicated by the physical property evaluation data 45d that does not meet the conditions.

[0101] (7) Other embodiments (7-1) In the above embodiment, the case in which the physical properties of the porous film are evaluated using image data 54a obtained by imaging with the imaging device 70 was described as an example.

[0102] In contrast, the physical properties of the porous film may be evaluated based on brightness uniformity reduction image data obtained by reducing the brightness uniformity of the porous film contained in the image data 54a through a predetermined process.

[0103] The brightness uniformity reduction image data may, for example, be data obtained by subtracting the corresponding smoothed image data from the image data 54a for each pixel, or it may be data obtained by subtracting the corresponding smoothed image data from the image data 54a for each pixel and then adding the average brightness value of the smoothed image data to each pixel.

[0104] In this case, the memory 54 of the physical property evaluation device 50 can store a smoothing program used to obtain smoothed image data from image data 54a. The processor 51 reads the smoothing program and executes it on the image data 54a to obtain smoothed image data by smoothing the image data 54a. The memory 54 then stores the image data 54a and the brightness uniformity reduction image data obtained from the smoothed image data in a state corresponding to the porous film's region correspondence data.

[0105] The smoothed image data is not particularly limited, but it can be an image obtained by blurring the image data 54a, for example, by applying Gaussian smoothing to the image data 54a.

[0106] Therefore, when evaluating the physical properties of thin, lightweight porous films, brightness unevenness may occur due to the influence of slight breezes, etc., when imaging while transporting the porous film. However, even in such cases, it is possible to suppress errors in physical property evaluation caused by the shaking of the porous film during imaging by performing physical property evaluation using brightness unevenness reduction image data.

[0107] (7-2) Regarding the image data 74a obtained by the imaging device 70, the brightness of the part close to the light source 19 may be higher than the brightness of the part far from the light source 19. For example, the image data may be corrected to obtain image data that reduces the effect of brightness due to distance from the light source 19.

[0108] (7-3) In the above embodiment, the example given was the case in which an air filter filter material 30 is manufactured with labels 80x attached to the parts where the evaluated physical properties do not meet predetermined physical property conditions.

[0109] In this case, the final air filter material obtained may be one from which portions that were determined not to meet the specified physical property conditions were removed by cutting or other means.

[0110] In addition, in the above embodiment, before laminating the permeable support layer onto the porous membrane, only the portions of the porous membrane whose evaluated physical properties meet predetermined physical property conditions may be selected, and the permeable support layer may be laminated only onto the portions of the porous membrane that meet the predetermined physical property conditions to obtain an air filter material.

[0111] Furthermore, in the filter media manufacturing apparatus 40, based on the physical property evaluation data 45d and the part correspondence data 45e, the processor 41 may determine which parts have physical properties that do not meet the predetermined physical property conditions, and the processor 41 may control known controllable cutting means, etc., so that only the parts where physical properties do not meet the predetermined physical property conditions are cut and removed.

[0112] The air filter material obtained in this manner can have a porous membrane whose evaluated physical properties satisfy predetermined physical property conditions.

[0113] (7-4) In the above embodiment, the physical property evaluation device 50 receives image data 74a of the porous film 31 acquired by the imaging device 70, and the physical property evaluation device 50 creates optical property data 54b from image data 54a corresponding to the image data 74a.

[0114] Alternatively, for example, the imaging device 70 may create optical property data from the acquired image data 74a of the porous film 31, and the imaging device 70 may send the optical property data to the physical property evaluation device 50.

[0115] (7-5) In the above embodiment, the case in which physical property evaluation data 54f and distribution evaluation data 54g are obtained based on optical property data 54b obtained from image data 54a was explained as an example.

[0116] In contrast, for example, physical property evaluation data 54f and distribution evaluation data 54g may be obtained based on image data 54a. In this case, although the reliability of the evaluation tends to be lower than when physical property evaluation data 54f and distribution evaluation data 54g are obtained based on optical property data 54b, as shown in Figure 5, it can be seen that the physical property distributions correspond when comparing image data 54a and distribution evaluation data 54g, so it is possible to perform a preliminary evaluation.

[0117] (8) Exam (8-1) Relationship between the optical properties of porous films and the pressure loss of porous films To confirm the correlation between the optical properties of porous membranes and their pressure drop, PTFE porous membranes were fabricated as follows, and tests were conducted to verify the correlation.

[0118] First, a mixture obtained by adding a predetermined amount of hydrocarbon oil as an extrusion aid to PTFE fine powder ("Polyflon F-104" manufactured by Daikin Industries, Ltd.) was formed into a round bar shape by paste extrusion. Then, this round bar shape was formed into a film shape using a calender roll heated to a predetermined temperature, and an unfired film was obtained by passing it through a hot air drying oven to evaporate and remove the extrusion aid.

[0119] Next, the unfired PTFE film was stretched longitudinally using the first manufacturing apparatus 40a, and the stretched film was wound onto the winding roll 2. Furthermore, one roll of the longitudinally stretched PTFE sheet obtained from the first manufacturing apparatus 40a (total length in the conveying direction is 110m and width in the direction of transport is 122cm) was stretched in the width direction in the stretching furnace 16 using the second manufacturing apparatus 40b to obtain a porous PTFE film.

[0120] Using the PTFE porous membrane obtained as described above, image data was acquired with the imaging device 70, and the pressure loss was measured using a pressure loss measuring instrument on the same porous membrane.

[0121] In the pressure loss measurement using a pressure loss measuring instrument, eight 10 cm circular cups were placed at predetermined intervals along the width direction of the porous membrane, and the pressure loss at each of the eight locations was measured. The pressure loss was then measured over the entire area of ​​one roll while shifting the position of the porous membrane in the conveying direction. The pressure loss was defined as the pressure loss when air was passed through the membrane in the direction of film thickness at a flow velocity of 5.3 cm / second, as described above.

[0122] Figure 5 shows (a) combined image data obtained by combining multiple image data obtained by the imaging device 70 in a continuous manner, (b) a heat map showing the distribution of brightness in the combined image data, and (c) a heat map showing the distribution of measured pressure loss values ​​measured by the pressure loss measuring instrument. In the heat map (b) showing the distribution of brightness in Figure 5, areas with high brightness are shown in red, and areas with low brightness are shown in blue. In the heat map (c) showing the distribution of measured pressure loss values ​​in Figure 5, areas with high pressure loss are shown in red, and areas with low pressure loss are shown in blue.

[0123] As is clear from the results in Figure 5, it was confirmed that (b) the heatmap of the brightness distribution of concatenated image data and (c) the heatmap of the distribution of measured pressure loss values ​​correspond substantially to each other.

[0124] Furthermore, Figure 6 shows a graph illustrating a calibration curve created to analyze the correlation between each luminance value in the concatenated image data and the measured pressure loss. Here, the p-value for the correlation test of this graph is 3.0218 × 10⁻⁶. -132 Since the result was 0.05 or less, a statistically significant correlation was confirmed between the luminance value and the pressure loss.

[0125] Furthermore, regarding the calibration curve in Figure 6, Figure 7 shows a graph of the calibration curve created by calculating the average value of the pressure loss for each unit of brightness, in order to perform an analysis that takes into account the frequency of plot appearance. Here, R 2 The value was 0.9872, which is close to 1, confirming a positive correlation between the luminance value and the pressure loss.

[0126] (8-2) Relationship between optical properties and pressure loss or film thickness when different types of filter media are used For air filter media consisting of a porous membrane sandwiched between permeable support layers on the windward and leeward sides, several types were prepared, and the following tests were conducted to confirm that there is a correlation between their optical properties and pressure loss or film thickness.

[0127] For each of the filter media types A to F, which employ a PTFE porous membrane as the air filter medium, multiple samples with different physical properties were prepared. The filter media types A to F were as follows:

[0128] As filter media type A, a sample of a PTFE porous membrane with a target pressure drop of 115 Pa and a collection efficiency of 99.9% or higher was prepared. For filter media type A, a single sample, a sample with two layers stacked together, and a sample with three layers stacked together were prepared.

[0129] For filter media type B, we prepared a sample of a PTFE porous membrane with a target pressure drop of 150 Pa and a collection efficiency of 99.99% or higher. For filter media type B, we prepared a single sample, a sample with two layers stacked together, and a sample with three layers stacked together.

[0130] For filter media type C, we prepared a sample of a PTFE porous membrane with a target pressure drop of 185 Pa and a collection efficiency of 99.999% or higher. For filter media type C, we prepared a single sample, a sample with two layers stacked together, and a sample with three layers stacked together.

[0131] For filter media type D, we prepared a sample of a PTFE porous membrane with a target pressure drop of 220 Pa and a collection efficiency of 99.9995% or higher. For filter media type D, we prepared a single sample, a sample with two layers stacked together, and a sample with three layers stacked together.

[0132] For filter media type E, a PTFE porous membrane sample was prepared with a target pressure drop of 145 Pa and a collection efficiency of 99.95% or higher. For filter media type E, both a single sample and a sample consisting of two stacked sheets were prepared.

[0133] As filter media type F, a sample of a PTFE porous membrane was prepared with a target pressure drop of 200 Pa and a collection efficiency of 99.995% or higher. For filter media type F, both a single sample and a sample of two stacked sheets were prepared.

[0134] For each of the above filter media types A to D (3 samples) and filter media types E to F (2 samples), a circular sample with a diameter of 10 cm was cut out. The median brightness value was determined from the image data, the pressure loss was measured using a pressure loss measuring instrument, and the film thickness was measured using a film thickness measuring instrument. The pressure loss was defined as the value obtained when air was passed through the film thickness direction at a flow velocity of 5.3 cm / second, as described above. The film thickness was defined as the total thickness measured by the film thickness measuring instrument with a load of 0.3 N applied in the thickness direction when multiple samples were stacked, and this value was divided by the number of stacked samples.

[0135] Figures 8 and 9 show graphs illustrating the relationship between brightness value and film thickness for three samples each of filter media types A to D and two samples each of filter media types E to F. Figure 9 is a magnified view of the three samples each of filter media types A to D shown in Figure 8. Figure 10 also shows a graph illustrating the relationship between brightness value and pressure loss for three samples each of filter media types A to D and two samples each of filter media types E to F.

[0136] Furthermore, Table 1 below shows the measured physical properties of three samples each for filter media types A to D and two samples each for filter media types E to F.

[0137] [Table 1]

[0138] As is clear from Figures 8 and 9, it was confirmed that for each sample of filter media types A to F, the film thickness increases as the brightness value increases.

[0139] As is clear from Figure 10, it was confirmed that for each sample of filter media types A to F, the relationship between increasing brightness and increasing pressure loss was observed. Furthermore, while the relationship between increasing brightness and increasing pressure loss is observed for both filter media types A to D and filter media types E to F, it is desirable to evaluate the pressure loss using different calculation algorithms for each type.

[0140] Next, 3498 samples were prepared for filter media type B, 3642 samples for filter media type C, and 4042 samples for filter media type D. For each type, the luminance value and pressure loss were measured, and calibration curves showing the relationship between luminance value and pressure loss were created. Figure 11 shows the graphs of the calibration curves for filter media types B, C, and D. Here, for filter media type B, it was determined that the physical properties were satisfied if the pressure loss was between 130 Pa and 170 Pa. For filter media type C, it was determined that the physical properties were satisfied if the pressure loss was between 170 Pa and 200 Pa. For filter media type D, it was determined that the physical properties were satisfied if the pressure loss was between 200 Pa and 240 Pa.

[0141] As can be seen from Figure 11, it became clear that the reliability of the evaluation is increased when the algorithm for showing the relationship between brightness value and pressure loss is used separately for each type of filter material.

[0142] (8-3) Relationship between optical properties and pressure loss or film thickness in porous polyethylene membranes Instead of the PTFE porous membrane used in (8-1) and (8-2) above, a sample of polyethylene porous membrane obtained by stretching polyethylene was prepared, and tests were conducted in the same manner as in (8-2) to investigate the relationship between brightness value and film thickness, and the relationship between brightness value and pressure loss.

[0143] Figure 12 shows a graph illustrating the relationship between brightness value and film thickness in a porous polyethylene membrane. Figure 13 shows a graph illustrating the relationship between brightness value and pressure loss in a porous polyethylene membrane.

[0144] As is clear from Figures 12 and 13, it was confirmed that for each sample of polyethylene porous membrane, the film thickness increases with increasing brightness, and the pressure loss increases with increasing brightness.

[0145] (Note) While embodiments of this disclosure have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of this disclosure as described in the claims. [Explanation of symbols]

[0146] 18. Anti-reflective sheet 19 Light source 30 Air filter media 31 Porous membrane 40. Filter media manufacturing equipment (porous membrane manufacturing equipment) 41. Processor (Porous film fabrication unit) 45c Stretching control data (porous film creation section) 45e, 54c, 82b Site-specific data 45d, 54f, 82a Physical property evaluation data 50. Physical property evaluation device 51 Processor (evaluation unit, acquisition unit) 52 Display (Output Section) 53 Transmitter / Receiver (Output Unit) 54 memory 54a Image data (optical data, two-dimensional optical properties data) 54b Optical properties data (optical data, two-dimensional optical properties data) 54c Body part correspondence data 54d Optical property extraction program (acquisition unit) 54e Material Property Evaluation Model (Evaluation Section) 54f Physical property evaluation data 54g distribution evaluation data 71 Camera (acquisition unit) 74a Image data (two-dimensional optical properties data) 100 Porous Membrane Management System (Equipment for Manufacturing Porous Membranes) [Prior art documents] [Patent Documents]

[0147] [Patent Document 1] Japanese Patent Publication No. 2020-163311

Claims

1. A device (50) for evaluating the physical properties of a porous membrane (31), The system includes an evaluation unit (54e, 51) that determines physical property evaluation data (54f) of at least one of the pressure loss and film thickness of the porous film based on the optical data (54b) of the porous film. A device for evaluating the physical properties of porous membranes.

2. The optical data (54b) is the two-dimensional optical data (54a, 54b) of the porous film. The aforementioned physical property evaluation data (54f) is physical property distribution evaluation data (54g) of at least one of the distributions of pressure loss and thickness in the porous membrane when the porous membrane is viewed from the thickness direction of the porous membrane. Apparatus for evaluating the physical properties of a porous film according to claim 1.

3. The system further includes output units (52, 53) that output the physical property distribution evaluation data obtained by the evaluation unit as two-dimensional data. Apparatus for evaluating the physical properties of a porous film according to claim 2.

4. The aforementioned optical data is characteristic data of the reflected and scattered light obtained when light irradiated onto the porous film is reflected and scattered by the porous film. Apparatus for evaluating the physical properties of a porous film according to any one of claims 1 to 3.

5. The optical data includes an index relating to the brightness of the reflected and scattered light, The aforementioned indicators relating to brightness include at least one of luminance, illuminance, luminous intensity, and brightness. Apparatus for evaluating the physical properties of a porous film according to claim 4.

6. A light source (19) that irradiates the porous film with the light, A reflection suppression sheet (18) is provided on the side opposite to the side where the light source is located relative to the porous film, Furthermore, it is equipped with Apparatus for evaluating the physical properties of a porous film according to claim 4.

7. The porous membrane contains fibers. Apparatus for evaluating the physical properties of a porous film according to any one of claims 1 to 3.

8. The porous membrane is a stretched porous membrane. Apparatus for evaluating the physical properties of a porous film according to any one of claims 1 to 3.

9. The porous membrane is a filter material that constitutes part of the air filter filter material (30). Apparatus for evaluating the physical properties of a porous film according to any one of claims 1 to 3.

10. The material properties to be evaluated are the porous membrane with a film thickness of 150 μm or less, or the porous membrane with a pressure loss of 200 Pa or less when air is passed through it in the direction of film thickness at a flow velocity of 5.3 cm / second. Apparatus for evaluating the physical properties of a porous film according to claim 9.

11. The aforementioned pressure loss is the pressure loss when air is passed through the porous membrane in the film thickness direction at a flow velocity of 5.3 cm / second. The evaluation unit, The evaluation algorithm includes a method for evaluating the pressure loss of the porous membrane based on the optical data of the porous membrane, for each of a plurality of predetermined ranges in the porous membrane. Does the system have an evaluation algorithm for evaluating the physical properties of a single porous film or a laminate of multiple porous films, where the evaluation algorithm is different for each number of porous film layers, based on the optical data of the porous film? Whether the evaluation algorithm, which evaluates the pressure loss for each of several predetermined ranges of the porous film based on the optical data of the porous film, is different for each number of layers of the porous film stacked together, when the physical properties of a single porous film or a stack of multiple porous films is to be evaluated, It is at least one of the following: Apparatus for evaluating the physical properties of a porous film according to claim 9.

12. The evaluation unit obtains the physical property evaluation data (54f) of the evaluation target area, in association with the part correspondence data (54c), based on the optical data (54b) of a predetermined evaluation target area when the porous film is viewed from the film thickness direction of the porous film, and part correspondence data (54c) indicating the evaluation target area associated with the optical data. Apparatus for evaluating the physical properties of a porous film according to any one of claims 1 to 3.

13. Based on the optics of the porous film (31), the physical properties of at least one of the pressure loss and film thickness of the porous film are evaluated. Methods for evaluating the physical properties of porous films.

14. With respect to the area to be evaluated in the porous membrane, an evaluation result is obtained by the method for evaluating the physical properties of the porous membrane described in claim 13. If the obtained evaluation results satisfy the predetermined conditions, an air filter filter material (30) having the porous membrane including the evaluation target part is manufactured. A method for manufacturing air filter media.

15. A manufacturing apparatus (40, 100) for a porous membrane (31), A porous film creation unit (45c, 41) that creates the porous film according to predetermined manufacturing conditions, An acquisition unit (71, 51, 54d) acquires two-dimensional optical data (54a, 54b) of the porous film created by the porous film fabrication unit, Based on the two-dimensional optical data of the porous film, an evaluation unit (54e, 51) obtains distribution evaluation data (54g) of at least one of the distributions of pressure loss and film thickness in the porous film when the porous film is viewed from the film thickness direction of the porous film, Equipped with, The porous film fabrication unit updates the contents of the predetermined manufacturing conditions based on the distribution evaluation data. Equipment for manufacturing porous membranes.

16. The porous film creation unit creates the porous film by stretching the object to be stretched. The predetermined manufacturing conditions include stretching conditions for the object to be stretched. Apparatus for manufacturing a porous membrane according to claim 15.

17. The stretching conditions for the object to be stretched include at least one of the stretching ratio, stretching temperature, and stretching speed. Apparatus for manufacturing a porous membrane according to claim 16.

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