JP2013052368A - Method and apparatus for washing object to be washed, and a pair of brush rollers for use in the method or apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce damage inflicted on an object to be washed in a washing process for scrub-washing the object to be washed simultaneously from both front and rear sides.SOLUTION: A pair of brush rollers 1A, 1B are insert-fitted to two rotating shafts respectively. In a cross section that includes the axes of the two rotating shafts almost orthogonally to the rotating direction of the two rotating shafts, the respective base end portions of a plurality of first protrusions 5A contacting a first washed surface 11A are projected to the object 10 to be washed from a direction substantially perpendicular to the first washed surface 11A to form a plurality of first regions La, and the respective base end portions of a plurality of second protrusions 5B contacting a second washed surface 11B are projected to the object 10 to be washed from a direction substantially perpendicular to the second washed surface 11B to form a plurality of second regions Lb. A plurality of overlap ranges Lp where the plurality of first regions La and the plurality of second regions Lb overlap are limited to a range of 80% or less to either of the first regions La and the second regions Lb including the overlap regions Lp regardless of the rotating positions of the two brush rollers 1A, 1B.

Description

  The present invention relates to a cleaning method, a cleaning apparatus, and a pair of brush rollers for an object to be cleaned mainly used in scrub cleaning in a cleaning process among manufacturing processes of electronic components such as semiconductor electronic device wafers, silicon wafers, and hard disks. .

  In the recent electronics industry, the precision of various parts has progressed dramatically, and the demand for cleanliness in the manufacturing environment has also increased. In particular, chemical contamination and adhering particles on the parts surface have a significant impact on product yield and operational reliability. Therefore, the importance of the cleaning process in the manufacturing process is extremely high, and various cleaning methods have been developed and implemented. Yes.

  For example, as a method for cleaning the surface (surface to be cleaned) of an object to be cleaned such as a semiconductor electronic device wafer, silicon wafer, hard disk, etc., for example, an elastic material composed of a polyvinyl acetal porous material and fixed to the outer periphery of a rotating shaft Scrub cleaning with a sponge roller (brush roller) having a substantially cylindrical roll body having a plurality of protrusions integrally formed on the outer peripheral surface of the roll body is known. Scrub cleaning refers to rubbing by bringing a plurality of protrusions on the outer peripheral portion of the roll body into contact with the surface to be cleaned and rotating a sponge roller through a rotating shaft while supplying water or other cleaning liquid to the contact portion between the two. It is something to wash.

Japanese Patent No. 3378015

  When the thin flat plate-like object to be cleaned by the scrub cleaning has a first surface to be cleaned and a second surface to be cleaned on the front and back, a pair of brush rollers (first brush roller and second brush Scrub cleaning using a brush roller is widely performed. The first brush roller and the second brush roller are respectively fixed to a first rotating shaft and a second rotating shaft that rotate in opposite directions while being arranged substantially parallel to each other. The object to be cleaned is disposed between a pair of brush rollers in a posture substantially parallel to the two rotation axes, the first protrusion is brought into rotational contact with the first surface to be cleaned, and the second surface to be cleaned. By rotating and contacting the second protrusion, the object to be cleaned can be scrubbed simultaneously from both the front and back sides.

  However, if the object to be cleaned is scrubbed simultaneously from both the front and back sides, the same part of the object to be cleaned may be simultaneously pressed by the protrusions from both the front and back sides, and the object to be cleaned that is pressed by the first or second protrusions If the ratio of the portions that are pressed simultaneously from both the front and back sides of the region becomes excessive, damage to the object to be cleaned may increase, which is not preferable in terms of quality.

  Therefore, an object of the present invention is to reduce damage to the object to be cleaned in the cleaning process in which the object to be cleaned is scrubbed simultaneously from both the front and back sides.

  In order to achieve the above object, in the cleaning method and the cleaning apparatus of the present invention, the first brush roller and the second brush roller that form a pair are each formed of a porous material having elasticity in a wet state. The first brush roller includes a substantially cylindrical first roll body and a plurality of first protrusions that integrally protrude from the outer peripheral surface of the first roll body with a substantially uniform density. The first brush roller is fixedly supported by the first rotation shaft in a state where the first rotation shaft is inserted through the inner diameter portion of the first roll body. The second brush roller has a substantially cylindrical second roll body and a plurality of second protrusions that integrally protrude from the outer peripheral surface of the second roll body at a substantially uniform density. The second brush roller is fixedly supported by the second rotation shaft in a state where the second rotation shaft is inserted into the inner diameter portion of the second roll body. The two rotating shafts are rotated in opposite directions while being arranged substantially parallel to each other. A thin flat plate-like object to be cleaned having a first surface to be cleaned and a second surface to be cleaned is disposed between the pair of brush rollers in a posture substantially parallel to two rotation axes. The object to be cleaned is simultaneously cleaned from both the front and back surfaces by rotating the first protrusion on the first surface to be cleaned and rotating the second protrusion on the second surface to be cleaned.

  The base end portions of the plurality of first protrusions that are in contact with the first surface to be cleaned in the cross section including the axis of the two rotation shafts substantially orthogonal to the rotation direction of the two rotation shafts. The plurality of first regions projected onto the object to be cleaned from the direction substantially perpendicular to the surface to be cleaned and the respective base end portions of the plurality of second protrusions in contact with the second surface to be cleaned are substantially the same as those of the second surface to be cleaned. A plurality of overlapping ranges in which the plurality of second regions projected onto the object to be cleaned from the vertical direction overlap with any of the first region and the second region including the overlapping range regardless of the rotational positions of the two brush rollers. Even within the range of 80% or less. That is, the ratio of the overlapping range to the first area (hereinafter referred to as the first overlapping ratio) and the ratio of the overlapping range to the second area (hereinafter referred to as the second overlapping ratio) are both 80% or less. . For this reason, the ratio of the part pressed simultaneously from both front and back sides in the area of the cleaning target pressed by the first or second protrusion does not become excessive, and the cleaned target is scrubbed simultaneously from both the front and back sides. In the cleaning process, damage to the object to be cleaned can be reduced.

  Note that the first and second rotating shafts may be rotated in synchronization with each other, or may be rotated independently (asynchronously).

  When the first and second rotating shafts are rotated asynchronously, in order to ensure a desired cleaning effect for each surface to be cleaned, the first overlapping ratio and the first overlapping rate during rotation of the rotating shaft (during rotation of the brush roller) The maximum value of the two overlapping ratios (hereinafter referred to as the protrusion overlapping ratio maximum value) is preferably 50% or more.

  The brush roller may be formed of a polyvinyl acetal resin porous material. In this case, the pore diameter of the porous material is preferably 50 μm or more and 200 μm or less, and the 30% compressive stress of the porous material is preferably 4 kPa or more and 15 kPa or less.

  Further, the pair of brush rollers of the present invention is used as the first and second brush rollers in the cleaning method or the cleaning apparatus. The first roll body and the second roll body have substantially the same shape, and the first protrusion and the second protrusion have substantially the same shape. The plurality of first protrusions and the plurality of second protrusions are arranged on the outer peripheral surface of the roll body according to a common basic pattern, and the first protrusion arrangement pattern and the second protrusion arrangement pattern are: The first roll body and the second roll body are displaced from each other in the axial direction of the inner diameter portion of the roll body in a comparison state in which the end face positions of the two roll bodies are aligned.

  The pair of brush rollers are fixedly supported on the respective rotation shafts so that the end faces of the two roll bodies are arranged in the same plane substantially orthogonal to the axis of the two rotation shafts. Thereby, even when the two rotation shafts are rotated asynchronously, the state in which the first region and the second region substantially coincide with each other on the front and back of the object to be cleaned during the rotation of the brush roller. It does not occur, and the maximum protrusion overlap ratio can be suppressed to 80% or less.

In order to ensure a desired cleaning effect for each surface to be cleaned, the number of protrusions arranged on the same circumference in the rotation direction of the outer peripheral surface of the roll body in each brush roller is preferably 4 or more and 40 or less. The number of protrusions arranged on the same straight line along the axial direction of the outer peripheral surface of the roll body is preferably 2 or more and 60 or less. Further, the shape of the protrusion is preferably substantially cylindrical, and the area of the top of the protrusion is preferably 1πcm ² or less. Furthermore, the maximum protrusion overlap ratio is preferably 50% or more.

  In the basic pattern, a plurality of protrusion arrangement rows along the circumferential direction of the outer peripheral surface of the roll body are set for each first predetermined interval along the axial direction of the inner diameter portion. Each projection arrangement row set above has a second predetermined interval so that the projection on the projection arrangement row and the projection on the other projection arrangement row are displaced in the circumferential direction by approximately ½ of the second predetermined interval. It may be an arrangement pattern in which a plurality of protrusions are arranged. In this case, it is preferable that the arrangement pattern of the first protrusions and the arrangement pattern of the second protrusions are shifted in the axial direction by approximately ½ of the first predetermined interval in the contrast state. By setting the two arrangement patterns so as to be shifted as described above, the maximum value of the protrusion overlap ratio during the asynchronous rotation of the brush roller can be minimized.

  ADVANTAGE OF THE INVENTION According to this invention, the damage given to a to-be-cleaned body can be reduced in the washing | cleaning process of scrub-cleaning a to-be-cleaned body from both front and back simultaneously.

It is a perspective view which shows the state which wash | cleans a to-be-cleaned body with a pair of brush roller which concerns on one Embodiment of this invention. It is a side view of the brush roller of FIG. It is the front view which looked at the deformation | transformation state of the protrusion at the time of scrub cleaning from the axial direction of the rotating shaft. It is sectional drawing which shows the overlapping range of a 1st area | region and a 2nd area | region. It is a figure which shows the arrangement pattern of the 1st projection, and the arrangement pattern of the 2nd projection by developing the peripheral surface of each roll object in the shape of a plane. It is a perspective view which shows the type | mold for shape | molding the brush roller of FIG. It is sectional drawing which shows the manufacturing method of the brush roller of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the protrusions are not shown.

  As shown in FIGS. 1 to 4, the object 10 to be cleaned is a thin disk-shaped wafer, and has a first surface 11 </ b> A and a second surface 11 </ b> B to be cleaned. .

  A pair of left and right brush rollers 1 (first brush roller 1A and second brush roller 1B) that perform scrub cleaning is a substantially cylindrical roll body 3 (first roll body 3A and second roll body 3B). And a plurality of protrusions 5 (first protrusions 5A and second protrusions 5B) that protrude integrally from the outer peripheral surface 12 (12A, 12B) of the roll body 3 (3A, 3B) at a substantially uniform density. . Each protrusion 5 has a cylindrical shape, and each roll body 3 has a substantially cylindrical rotating shaft 2 (a first rotating shaft 2A and a second rotating shaft 2B) formed of a hard material such as metal or plastic. ) Is installed. In addition, the shape of the protrusion 5 is not limited to the cylindrical shape.

  In scrub cleaning, the left and right rotating shafts 2 are separated by a predetermined distance and are arranged substantially in parallel, and the left and right roll bodies 3 ( The object to be cleaned 10 is sandwiched between the protrusion 5A of the first roll body 3A and the protrusion 5B of the second roll body 3B, and the surface to be cleaned 11 (the first surface to be cleaned 11A and the second surface to be cleaned 11B). ), The left and right rotating shafts 2 are rotated in opposite directions (the direction of rotation is indicated by an arrow 7), and the object to be cleaned 10 (the object to be cleaned is centered on the rotating shaft 6 substantially orthogonal to the rotating shaft 2). This is done by rotating the cleaning surface 11) (the direction of rotation is indicated by the arrow 8). When the protrusion 5A of the first roll body 3A is in rotational contact with the rotating first cleaned surface 11A, the first cleaned surface 11A is scrubbed, and the second cleaned surface 11B is rotated second. When the protrusion 5B of the roll body 3B is in rotational contact, the second surface 11B to be cleaned is scrubbed.

  The arrangement of the pair of brush rollers 1 is not limited to the left and right arrangements as described above. For example, the pair of brush rollers 1 is arranged vertically or obliquely. It can be arranged in various ways. Further, the rotation shaft 6 of the object to be cleaned 10 may be set so as to be substantially orthogonal to the rotation shaft 2 of the brush roller 1. For example, the pair of brush rollers 1 and the rotation shaft 2 are arranged in a substantially horizontal direction. In this case, the rotation shaft 6 of the object to be cleaned 10 may be set in a substantially vertical direction. Further, the first and second rotating shafts 2A and 2B may be rotated so as to be synchronized, or may be rotated independently (asynchronously).

  The brush roller 1 (roll body 3 and protrusion 5) is made of a polyvinyl acetal porous material (PVAt porous material) having elasticity in a water-containing state. The PVAt porous material is cured in a dry state and softened in a wet state. Further, the PVAt porous material is excellent in water absorption and water retention, exhibits favorable flexibility when wet and moderate rebound resilience, and is excellent in abrasion resistance. The rotating shaft 2 is inserted into the inner diameter portion of the roll body 3 and fixedly supports the roll body 3. For example, the outer peripheral surface of the rotating shaft 2 and the inner peripheral surface of the roll body 3 may be fixed by an adhesive, and the outer diameter of the rotating shaft 2 is formed larger than the inner diameter of the roll body 3. The roll body 3 may be fixedly supported on the rotary shaft 2 by the elastic force of the roll body 3 by press-fitting into the inner diameter portion of the roll body 3. Further, when the roll body 3 is manufactured, the roll body 3 may be fixed or supported on the rotary shaft 2 by using the rotary shaft 2 instead of the core rod 29 shown in FIG. In this case, the brush roller 1 (roll body 3) after the reaction is taken out of the mold 21 with the rotating shaft 2 and washed with water. By such fixed support, the roll body 3 rotates together with the rotating shaft 2.

  As shown in FIG. 3, during scrub cleaning, the first and second protrusions 5A and 5B abut against the first and second cleaned surfaces 11A and 11B, respectively, and elastically deform backward in the rotational direction 7. . At this time, the first protrusion 5A presses the first surface to be cleaned 11A, and the second protrusion 5B presses the second surface to be cleaned 11B. For this reason, there is a possibility that the same portion of the object to be cleaned 10 is simultaneously pressed by the protrusions 5 from both the front and back sides, and both the front and back sides of the region of the object to be cleaned 10 pressed by the first or second protrusions 5A and 5B. If the ratio of the parts pressed simultaneously is excessive, damage to the object to be cleaned 10 may be increased, which is not preferable in terms of quality. Therefore, in order to prevent the quality of the object to be cleaned 10 from deteriorating, the ratio of the portions that are simultaneously pressed from both the front and back sides in the region of the object to be cleaned 10 pressed by the first or second protrusions 5A and 5B is excessive. It is necessary to suppress becoming.

  However, since the protrusion 5 during scrub cleaning presses the surface 11 to be cleaned while elastically deforming backward in the rotation direction 7, the region of the object 10 to be cleaned that is pressed by the first or second protrusion 5 </ b> A, 5 </ b> B. It is extremely difficult to actually measure.

  Therefore, in the present invention, it is assumed that the protrusion 5 during scrub cleaning is compressed and deformed only in the protruding direction (substantially orthogonal to the surface 11 to be cleaned) and is in contact with the surface 11 to be cleaned. As shown in FIG. 4, in the cross section including the axis of these two rotary shafts 2 </ b> A, 2 </ b> B substantially orthogonal to the rotational direction of 2 </ b> B, as shown in FIG. A plurality of first projections in which the base end portions of the plurality of first protrusions 5A that are in contact with the cleaning surface 11A are projected onto the body to be cleaned 10 (first cleaning surface 11A) from a direction substantially perpendicular to the first cleaning surface 11A. One base (distance) La and each base end portion of the plurality of second protrusions 5B that are in contact with the second surface to be cleaned 11B are to be cleaned 10 from the substantially vertical direction of the second surface to be cleaned 11B (second A plurality of second regions (distances) Lb projected onto the surface to be cleaned 11B), and these first regions La and second regions Lb And a plurality of overlapping range (distance) Lp overlapping is defined as the determination parameter. Regardless of the rotational position of the two brush rollers 1A and 1B, each of the plurality of overlapping ranges Lp is 80% or less with respect to both the first region La and the second region Lb including the overlapping region Lp. The range is limited (Lp / La ≦ 0.8, Lp / Lb ≦ 0.8). This is because if the overlapping range exceeds 80%, the object to be cleaned 10 is greatly damaged, which is not preferable in terms of quality. In FIG. 4, only a pair of protrusions 5 that overlap each other is illustrated, and illustration of the other protrusions 5 is omitted. However, the overlapping range of other protrusions 5 is also limited to 80% or less. .

  When the two rotary shafts 2A and 2B are rotated synchronously, the relative rotational positions of the brush rollers 1A and 1B do not vary with time. Accordingly, the brush rollers 1A and 1B (rotating shafts 2A and 2B) are set so that the ratio of the overlapping range Lp to the first region La and the second region Lb does not exceed 80% during the rotation of the rotating shafts 2A and 2B. What is necessary is just to set the relative rotation position.

  On the other hand, when the first and second rotating shafts 2A and 2B are rotated asynchronously, the relative rotational positions of the brush rollers 1A and 1B vary with time, and the overlapping range Lp also varies with time. The ratio of the overlapping range Lp to the first area La (first overlapping ratio) and the ratio of the overlapping range Lp to the second area Lb (second overlapping ratio) also vary. Therefore, the shape and number of the first protrusions 5A and the second protrusions 5B are set so that the maximum value of the first overlap ratio and the second overlap ratio (protrusion overlap ratio maximum value) that varies with time does not exceed 80%. It is necessary to set the position and the like.

  Further, the maximum value of the protrusion overlap ratio is preferably 50% or more. This is because if the maximum protrusion overlap ratio is less than 50%, the density of the protrusions 5 may be reduced on one or both of the outer peripheral surfaces 12A and 12B, and a desired cleaning effect may not be obtained.

  The two brush rollers 1A and 1B of the present embodiment have substantially the same shape. That is, the first roll body 3A and the second roll body 3B have substantially the same shape, and the first protrusion 5A and the second protrusion 5B have substantially the same cylindrical shape.

  Further, as shown in FIG. 5, the plurality of first protrusions 5A and the plurality of second protrusions 5B are respectively arranged on the outer peripheral surfaces 11A and 11B of the roll bodies 3A and 3B according to a common basic pattern. In the basic pattern, a plurality of protrusion arrangement rows along the circumferential direction of the outer peripheral surface 11 of the roll body 3 are set for each first predetermined interval D1 along the axial direction of the inner diameter portion. The projections 5 on one projection arrangement row and the projections 5 on the other projection arrangement row are shifted in the circumferential direction by about ½ of the second predetermined distance D2 on the set projection arrangement rows. This is an arrangement pattern in which a plurality of protrusions 5 are arranged every two predetermined intervals D2. By adopting such a basic pattern of the protrusion arrangement, the surface 11 to be cleaned can be efficiently cleaned. FIG. 5 shows the center line 15 of the protrusion arrangement row.

  However, the arrangement pattern of the first protrusions 5A and the arrangement pattern of the second protrusions 5B are not completely the same, and the two roll bodies 3A and 3B are arranged with their end faces 13A and 13B aligned. In contrast, the roll bodies 3A and 3B are displaced from each other in the axial direction of the inner diameter portion. In the present embodiment, the arrangement pattern of the first protrusions and the arrangement pattern of the second protrusions are shifted in the axial direction by approximately ½ of the first predetermined distance D1 in the above-described comparison state.

In order to secure a desired cleaning effect on the surface 11 to be cleaned, the number of the protrusions 5 arranged on the same circumference (on the same protrusion arrangement row) in the rotation direction of the outer peripheral surface 12 of the roll body 3 is four or more. 40 or less is suitable, and the number of the protrusions 5 arranged on the same straight line along the axial direction of the outer peripheral surface 12 of the roll body 3 is preferably 2 or more and 60 or less. Further, the area of the top of the protrusion 5 is preferably 1πcm ² or less.

  The pair of brush rollers 1A, 1B has their respective rotary shafts so that the end faces 13A, 13B of the two roll bodies 3A, 3B are arranged in the same plane substantially orthogonal to the axis of the two rotary shafts 2A, 2B. 2A and 2B are fixedly supported. In this roller insertion state, the arrangement pattern of the first protrusions 5A and the arrangement pattern of the second protrusions 5B are shifted from each other in the axial direction of the rotation shafts 2A and 2B, so that the two rotation shafts 2A and 2B are asynchronous. Even when the brush rollers 1A and 1B are rotated, the state in which the first region La and the second region Lb substantially coincide with each other on the front and back of the object to be cleaned 10 does not occur. The maximum protrusion overlap ratio can be suppressed to 80% or less.

  In particular, since the displacement between the arrangement patterns in the roller insertion state is approximately ½ of the first predetermined interval D1, the maximum protrusion overlap ratio during asynchronous rotation of the brush roller can be minimized.

  The brush roller 1 made of a PVAt porous material is prepared by mixing, for example, one or more polyvinyl alcohols (raw materials) having an average polymerization degree of 500 to 3000 and a saponification degree of 80% or more to form an aqueous solution. Mineral acids as catalysts, starch and the like as pore-forming agents are added, and these mixed solutions are injected into a predetermined mold 21 as shown in FIGS. 6 and 7, and reacted at 40 to 80 ° C. After removing from 21, the pore-forming agent and the like are removed by washing with water.

  The mold 21 includes an outer mold 23, an inner mold 25, a bottom plate 27, a core rod 29, and a cap 31. Both the outer mold 23 and the inner mold 25 are formed in a cylindrical shape. The inner mold 25 has an outer diameter that is the same as or slightly smaller than the inner diameter of the outer mold 23, and is inserted into the outer mold 23. The core rod 29 is inserted approximately at the center of the inner mold 25. The bottom plate 27 closes the lower ends of the outer mold 23 and the inner mold 25 and supports the lower end of the core rod 29. The cap 31 is fitted to the inner peripheral surface at the upper end of the outer mold 23. The core rod 29 is positioned by the bottom plate 27 and the cap 31.

  A substantially cylindrical space 33 for forming the roll body 3 is defined between the inner peripheral surface of the inner mold 25 and the outer peripheral surface of the core rod 29. A plurality of through holes 35 for forming the protrusions 5 are formed in the inner mold 25, and each through hole 35 communicates with the space 33. The mixed liquid is injected into the space 33 from the casting nozzle 43 inserted between the outer mold 23 and the cap 31 and flows into the through holes 35 from the space 33. At the same time, the air in the through hole 35 moves to the space 33 and is released from the upper end of the space 33 to the atmosphere. Thereby, the liquid mixture is reliably filled up to the end of the through hole 35.

  Moreover, the 30% compressive stress (physical property value) of the brush roller 1 in an appropriate water-containing state is preferably 4 kPa or more and 15 kPa or less. The proper water content state refers to a water content state in which the PVAt porous material can exhibit an appropriate elasticity, and the water content (weight% of the water content state relative to the dry state) is obtained in a range of approximately 100% to 1500%. The 30% compressive stress means that the PVAT-based porous material with proper water content is cut so that the distance between both end faces (height in the longitudinal direction) is 30 mm, and a load is applied to the entire end face. It is set to a type load measuring instrument, and the load when it is crushed by 30% (9 mm) in the longitudinal direction is measured and obtained as a value obtained by dividing the load by the area of the end face.

  Moreover, as a PVAt type | system | group porous material, the porosity of the internal structure | tissue is 80% or more and 95% or less, and an average pore diameter is 50 micrometers or more and 200 micrometers or less.

  This is because if the porosity is less than 80%, the flexibility when wet is insufficient, and if the porosity is more than 95%, the practical strength is poor and none is suitable for cleaning applications. Further, if the average pore diameter is smaller than 50 μm, the elasticity at the time of wetting is insufficient and a sufficient brushing effect cannot be obtained, and if it exceeds 200 μm, the eyes are too coarse to be suitable for precision cleaning.

  The porosity is measured with a dry automatic dense watch on a dry rectangular parallelepiped PVAt sufficiently dried by a dryer, and from the apparent volume and true volume of the rectangular parallelepiped, the following equation (1) This is a calculated value.

  Porosity (%) = (apparent volume−true volume) / apparent volume × 100 (1)

  The average pore diameter is an average value of the diameters of a plurality of pores present in the internal structure of the PVAt porous material. In this embodiment, the average value of the long diameters (distances in the longitudinal direction of each pore) of a predetermined number of pores extracted from a plurality of pores on a predetermined basis is defined as the average pore diameter, and is obtained, for example, by the following measurement method Can do.

  The brush roller 1 is cut at a predetermined position, and the internal tissue exposed on the cut surface is photographed with an electron microscope. Next, a predetermined measurement range is set in the photographed photograph, and 20 pores are extracted in descending order of the longest diameter from a plurality of pores existing in the measurement range. Next, each major axis of the 20 extracted pores is measured. Finally, the average of the 11th to 20th measurement values counted from the larger of the 20 measurement values is calculated as the average pore diameter.

Furthermore, as the PVAt porous material, those having an apparent density of 0.06 g / cm ³ or more and a water retention of 600% or more are suitable.

  The apparent density is calculated by measuring the dry weight of the PVAt porous material of a predetermined shape (for example, rectangular shape) and the external dimensions under proper water content, and calculating the volume (wet volume) from the external dimensions. And obtained by dividing the dry weight by the wet volume.

  The water retention rate is a value calculated by the following equation (2) by measuring the dry weight of the PVAt porous material (dry weight) and the weight sufficiently wet (wet weight). is there.

  Water retention rate (%) = (wet weight−dry weight) / dry weight × 100 (2)

  As described above, according to the present embodiment, it is possible to reduce damage to the object to be cleaned 10 in the cleaning process in which the object 10 to be cleaned is scrubbed simultaneously from both the front and back sides.

  In addition, this invention is not limited to the above-mentioned embodiment described as an example, and its modification, In the range which does not deviate from the technical idea which concerns on this invention even if it is other than the above-mentioned embodiment etc. If so, various changes can be made according to the design and the like.

  For example, the shape and basic pattern of the protrusion 5 are not limited to the above and are arbitrary. Further, the protrusions 5 may be arranged in different basic patterns on the two brush rollers 1A and 1B, and the first protrusion 5A and the second protrusion 5B may be set to different shapes and sizes. Further, the first roll body 2A and the second roll body 2B may be set to different sizes.

DESCRIPTION OF SYMBOLS 1,1A, 1B ... Brush roller, 2, 2A, 2B ... Rotating shaft, 3, 3A, 3B ... Roll body, 5, 5A, 5B ... Projection, 10 ... Body to be cleaned, 11, 11A, 11B ... Surface to be cleaned , 12, 12A, 12B ... outer peripheral surface, La ... first region, Lb ... second region, Lp ... overlapping region

Claims (5)

The first brush roller and the second brush roller that form a pair are each formed of a porous material having elasticity in a wet state, and the first brush roller includes a first roll body having a substantially cylindrical shape and the first roll body. A plurality of first protrusions integrally projecting from the outer peripheral surface of one roll body at a substantially uniform density, and the first rotating shaft is inserted through the inner diameter portion of the first roll body. The second brush roller is fixedly supported by the first rotating shaft, and the second brush roller protrudes integrally from the substantially cylindrical second roll body and the outer peripheral surface of the second roll body at a substantially uniform density. A plurality of second protrusions, and is fixedly supported by the second rotating shaft in a state where the second rotating shaft is inserted into the inner diameter portion of the second roll body, and the two rotating shafts are Rotate in opposite directions while being arranged substantially parallel to each other, and A thin flat plate-like object to be cleaned having a surface and a second surface to be cleaned is disposed between the pair of brush rollers in a posture substantially parallel to the two rotation shafts. A method for cleaning an object to be cleaned, wherein the object to be cleaned is simultaneously cleaned from both front and back surfaces by rotating the first protrusion on the cleaning surface and rotating the second protrusion on the second surface to be cleaned. Because
The base end portions of the plurality of first protrusions that are in contact with the first surface to be cleaned in the cross section including the axis of the two rotation shafts substantially orthogonal to the rotation direction of the two rotation shafts. A plurality of first regions projected onto the object to be cleaned from a substantially vertical direction of the first surface to be cleaned, and respective base end portions of the plurality of second protrusions contacting the second surface to be cleaned Each of the plurality of overlapping ranges in which the plurality of second regions projected onto the object to be cleaned from the substantially vertical direction of the two surfaces to be cleaned includes the overlapping range regardless of the rotational position of the two brush rollers. The method for cleaning an object to be cleaned is characterized by being limited to a range of 80% or less for both the first region and the second region. A pair of first brush roller and second brush roller are provided, and each of the pair of brush rollers is formed of a porous material having elasticity in a wet state, and the first brush roller is substantially cylindrical. A first roll body having a shape and a plurality of first protrusions integrally projecting from the outer peripheral surface of the first roll body at a substantially uniform density; The second brush roller is fixedly supported by the first rotating shaft in a state of being inserted through the first rotating shaft, and the second brush roller is formed from a substantially cylindrical second roll body and an outer peripheral surface of the second roll body. A plurality of second protrusions protruding integrally at a substantially uniform density, and fixed to the second rotation shaft in a state where the second rotation shaft is inserted into the inner diameter portion of the second roll body. The two rotating shafts are arranged substantially parallel to each other. The thin plate-like object to be cleaned, which rotates in opposite directions and has a first surface to be cleaned and a second surface to be cleaned, has the pair of brushes in a posture substantially parallel to the two rotation axes. The first protrusion is in rotation contact with the first surface to be cleaned, and the second protrusion is in rotation contact with the second surface to be cleaned. A cleaning device for an object to be cleaned at the same time from both front and back sides,
The base end portions of the plurality of first protrusions that are in contact with the first surface to be cleaned in the cross section including the axis of the two rotation shafts substantially orthogonal to the rotation direction of the two rotation shafts. A plurality of first regions projected onto the object to be cleaned from a substantially vertical direction of the first surface to be cleaned, and respective base end portions of the plurality of second protrusions contacting the second surface to be cleaned Each of the plurality of overlapping ranges in which the plurality of second regions projected onto the object to be cleaned from the substantially vertical direction of the two surfaces to be cleaned includes the overlapping range regardless of the rotational position of the two brush rollers. The apparatus for cleaning an object to be cleaned is limited to a range of 80% or less for both the first area and the second area. A pair of brush rollers used as the first and second brush rollers in the cleaning method according to claim 1 or the cleaning device according to claim 2,
The first roll body and the second roll body have substantially the same shape,
The first protrusion and the second protrusion have substantially the same shape,
The plurality of first protrusions and the plurality of second protrusions are arranged on the outer peripheral surface of the roll body according to a common basic pattern, and the arrangement pattern of the first protrusions and the arrangement of the second protrusions The pattern is characterized in that the first roll body and the second roll body are shifted from each other in the axial direction of the inner diameter portion of the roll body in a comparison state in which the end face positions of both are aligned. A pair of brush rollers. A pair of brush rollers according to claim 3,
In the basic pattern, a plurality of protrusion arrangement rows along the circumferential direction of the outer peripheral surface of the roll body are set for each first predetermined interval along the axial direction of the inner diameter portion, and in two adjacent protrusion arrangement rows, The projections on one projection arrangement row and the projections on the other projection arrangement row are shifted in the circumferential direction by about ½ of the second predetermined interval, and the second projection arrangement row is set on the second projection arrangement row. Is an arrangement pattern in which a plurality of protrusions are arranged at predetermined intervals.
The arrangement pattern of the first protrusion and the arrangement pattern of the second protrusion are shifted in the axial direction by approximately ½ of the first predetermined interval in the comparison state. Brush roller. A pair of brush rollers according to claim 3 or claim 4,
The pair of brush rollers are fixedly supported by the two rotating shafts so that the end faces of the two roll bodies are arranged in the same plane substantially orthogonal to the axis of the two rotating shafts,
During the rotation of the two rotating shafts, the maximum value of the ratio of the overlapping range to the first region and the maximum value of the ratio of the overlapping range to the second region are both 50% or more. A pair of brush rollers.

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