Patent Publication Number: US-2018042440-A1

Title: Cleaning sheet and cleaning instrument

Description:
TECHNICAL FIELD 
     The present invention relates to a cleaning sheet and a cleaning tool for cleaning an object to be cleaned. 
     BACKGROUND ART 
     Japanese Unexamined Patent Application Publication (JP-A) No. 2014-150963 discloses a cleaning sheet configured to be attached to a holder. In the cleaning sheet, a cleaning operation is performed by using a cleaning side sheet having strips and a fiber assembly. Further, in the cleaning operation, the strips and constituent fibers of the fiber assembly are raised, so that a space for capturing dust is provided between the strips and the constituent fibers of the fiber assembly. Specifically, by providing the space for capturing dust in a region of the cleaning sheet which is actually used for cleaning operation, the cleaning sheet has an effective cleaning function. 
     In forming the space for capturing dust, however, further improvement is desired. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: JP-A No. 2014-150963 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     Accordingly, it is an object of the present invention to provide a more rational constructing technique relating to a structure for providing a space for capturing dust in a cleaning region which is actually used for cleaning operation. 
     Invention to Solve the Problem 
     In order to solve the above problem, a cleaning sheet according to the present invention is provided which is configured to be attached to a holder and has a holding region which is attached to the holder and a cleaning region which comes in contact with an object to be cleaned. 
     The holding region has sheet elements and a receiving part configured to receive the holder and formed by superposing the sheet elements. Specifically, the receiving part is configured to be removably attached to the holder. 
     The cleaning region has a fiber bundle, a cleaning side sheet-like member superposed on the fiber bundle, and a bonding part that bonds the fiber bundle and the cleaning side sheet-like member. The fiber bundle is formed by arranging a plurality of fiber bundle constituent fibers having prescribed orientation. The cleaning side sheet-like member has a first surface facing the fiber bundle, a second surface on the side opposite to the first surface, a cut element and a strip element defined by the cut element. The cut element consists of a plurality of cuts. The strip element is formed between adjacent ones of the cuts and has a first strip and a second strip. Further, the strip element has a plurality of strips, and any pair of the strips can be respectively defined as the first strip and the second strip. 
     The fiber bundle constituent fibers are configured to be bent along the bonding part so as to be raised up in a direction away from the holding region. Each of the first strip and the second strip has a first engagement part formed on the first surface and a second engagement part formed on the second surface and is configured to be bent along the bonding part so as to be raised up in a direction away from the holding region. Specifically, when the fiber bundle constituent fibers and the first and second strips are raised, a space for capturing dust is formed between the fiber bundle constituent fibers and the first and second strips. Further, a user can raise the fiber bundle constituent fibers and the first and second strips by holding both ends of the cleaning sheet with both hands and alternately moving the hands up and down, or by shaking the user&#39;s hand holding the holder attached to the cleaning sheet. 
     With the above-described structure, it is configured such that, when the first and second strips are raised, the first engagement part can be engaged with the fiber bundle constituent fibers and the second engagement part of the first strip and the second engagement part of the second strip can be engaged with each other. 
     The cleaning sheet according to this invention is raised, while the first engagement parts of the strips are engaged with the fiber bundle constituent fibers and the first and second strips are engaged with each other via the respective second engagement parts. Therefore, particularly in an early stage of a cleaning operation, the raised state of the strips and the fiber bundle constituent fibers can be easily maintained. The term “engagement” or “engage” as used in the present invention is explained. For example, when the cleaning side sheet-like member is a nonwoven fabric, the cleaning side sheet-like member has nonwoven fabric constituent fibers forming the nonwoven fabric. Therefore, the engagement between the first strip and the second strip means that the nonwoven fabric constituent fibers of the first and second strips are entangled with each other. Further, the “engagement” between the strips and the fiber bundle constituent fibers means that the nonwoven fabric constituent fibers of the strips and the fiber bundle constituent fibers are entangled with each other. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the cleaning side sheet-like member has a first direction which is defined by a direction from the bonding part toward a free end of the strip element, and a second direction crossing the first direction. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the cleaning side sheet-like member may be formed of nonwoven fabric. In this case, the nonwoven fabric may have a plurality of nonwoven fabric constituent fibers having orientation in the first direction. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the first engagement part may be formed of the nonwoven fabric constituent fibers exposed to the first surface. In the cleaning sheet according to this aspect, the nonwoven fabric constituent fibers and the fiber bundle constituent fibers can be engaged with each other. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the second engagement part may be formed of the nonwoven fabric constituent fibers exposed to the second surface. In the cleaning sheet according to this aspect, the nonwoven fabric constituent fibers of the first strip and the nonwoven fabric constituent fibers of the second strip can be engaged with each other. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the nonwoven fabric preferably has higher rigidity in the first direction than in the second direction. 
     In an aspect of the solution in the cleaning sheet according to the present invention, preferably, the nonwoven fabric has rigidity of 69.7 mm to 80.0 mm in the first direction and rigidity of 35.0 mm to 39.9 mm in the second direction. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the nonwoven fabric preferably has total light transmittance of 83.03 to 88.43%. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the nonwoven fabric preferably has a larger average surface friction coefficient in the first direction on the second surface than on the first surface. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the nonwoven fabric preferably has an average surface friction coefficient of 0.126 to 0.129μ in the first direction on the first surface and an average surface friction coefficient of 0.138 to 0.145μ in the first direction on the second surface. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the nonwoven fabric preferably has a larger average surface friction coefficient in the second direction on the second surface than on the first surface. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the nonwoven fabric preferably has an average surface friction coefficient of 0.136 to 0.137μ in the second direction on the first surface and an average surface friction coefficient of 0.145 to 0.163μ in the second direction on the second surface. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the nonwoven fabric preferably has a larger average deviation of surface roughness in the first direction on the second surface than on the first surface. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the nonwoven fabric preferably has an average deviation of surface roughness of 3.225 to 3.350μ in the first direction on the first surface and an average deviation of surface roughness of 3.250 to 3.535μ in the first direction on the second surface. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the sheet element may be a laminate sheet formed by superposing a first sheet-like member and a second sheet-like member one on the other. In this case, the laminate sheet has a first sheet bonding part which bonds the first and second sheet-like members, and a second sheet bonding part which is spaced apart from the first sheet bonding part and bonds the first and second sheet-like members. With this structure, the receiving part may be defined by a space surrounded by the first sheet-like member, the second sheet-like member, the first sheet bonding part and the second sheet bonding part. 
     In an aspect of the solution in the cleaning sheet according to the present invention, the sheet element may be a single sheet-like member. The sheet-like member has a superposed part formed by superposing regions spaced apart from each other in the sheet-like member one on the other, and a sheet bonding part which bonds the superposed regions of the sheet-like member in the superposed part. With this structure, the receiving part may be defined by a space surrounded by the sheet bonding part and a region of the sheet-like member which extends in a loop between the spaced-apart regions bonded at the sheet bonding part. 
     In order to solve the above-described problem, a cleaning tool according to the present invention is provided which has a holder and a cleaning sheet attached to the holder. The holder has a grip configured to be held by a user, and a long part connected to the grip. The cleaning sheet has a holding region attached to the long part and a cleaning region which comes in contact with an object to be cleaned. 
     The holding region has sheet elements and a receiving part configured to receive the holder and formed by superposing the sheet elements. Specifically, the receiving part is configured to be removably attached to the holder. 
     The cleaning region has a fiber bundle, a cleaning side sheet-like member superposed on the fiber bundle, and a bonding part that bonds the fiber bundle and the cleaning side sheet-like member. The fiber bundle is formed by arranging a plurality of fiber bundle constituent fibers having prescribed orientation. The cleaning side sheet-like member has a first surface facing the fiber bundle, a second surface on the side opposite to the first surface, a cut element and a strip element defined by the cut element. The cut element consists of a plurality of cuts. The strip element is formed between adjacent ones of the cuts and has a first strip and a second strip. Further, the strip element has a plurality of strips, and any pair of the strips can be respectively defined as the first strip and the second strip. 
     The fiber bundle constituent fibers are configured to be bent along the bonding part so as to be raised up in a direction away from the holding region. Each of the first and second strips has a first engagement part formed on the first surface and a second engagement part formed on the second surface and is configured to be bent along the bonding part so as to be raised up in a direction away from the holding region. Specifically, when the fiber bundle constituent fibers and the first and second strips are raised, a space for capturing dust is formed between the fiber bundle constituent fibers and the first and second strips. Further, a user can raise the fiber bundle constituent fibers and the first and second strips by holding both ends of the cleaning sheet with both hands and alternately moving the hands up and down, or by shaking the user&#39;s hand holding the holder attached to the cleaning sheet. 
     With the above-described structure, it is configured such that, when the first and second strips are raised, the first engagement part can be engaged with the fiber bundle constituent fibers and the second engagement part of the first strip and the second engagement part of the second strip can be engaged with each other. 
     In the cleaning tool according to the present invention, the cleaning sheet is raised, while the first engagement parts of the strips are engaged with the fiber bundle constituent fibers and the first and second strips are engaged with each other via the respective second engagement parts. Therefore, particularly in an early stage of a cleaning operation, the raised state of the strips and the fiber bundle constituent fibers can be easily maintained. 
     Effect of the Invention 
     According to the present invention, a more rational constructing technique relating to a structure for providing a space for capturing dust in a cleaning region is provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a cleaning tool according to a first embodiment of the present invention. 
         FIG. 2  is a plan view showing a holder according to the first embodiment of the present invention. 
         FIG. 3  is a plan view showing a cleaning sheet according to the first embodiment of the present invention. 
         FIG. 4  is a bottom view of the cleaning sheet. 
         FIG. 5  is a sectional view taken along line II-II in  FIG. 3 . 
         FIG. 6  is an explanatory drawing for illustrating a strip element. 
         FIG. 7  is an explanatory drawing for illustrating the strip element and a fiber bundle. 
         FIG. 8  is an explanatory drawing for illustrating operation of the strip element and the fiber bundle. 
         FIG. 9  is an explanatory drawing for illustrating a cleaning sheet according to a second embodiment of the present invention. 
     
    
    
     EMBODIMENTS FOR CARRYING OUT THE INVENTION 
     Description of First Embodiment 
     A first embodiment of the present invention is now described with reference to  FIGS. 1 to 8 .  FIG. 1  is a perspective view showing a cleaning tool A 100 . As shown in  FIG. 1 , the cleaning tool A 100  includes a holder C 100  and a cleaning sheet B 100  which is removably attached to the holder C 100 . The cleaning sheet B 100  has a holding region B 110  to which the holder C 100  is attached. Further, a region of the cleaning sheet B 100  which comes in contact with an object to be cleaned forms a cleaning region B 120 . The cleaning tool A 100 , the holder C 100 , the cleaning sheet B 100 , the holding region B 110  and the cleaning region B 120  are example embodiments that correspond to the “cleaning tool”, the “holder”, the “cleaning sheet”, the “holding region” and the “cleaning region”, respectively, according to the present invention. 
     The cleaning sheet B 100  may be sold alone or sold as the cleaning tool A 100  in a package in which the cleaning sheet B 100  and the holder C 100  are packed together. The cleaning sheet B 100  may be of disposable type designed for single use, or disposable type designed for multiple use which can be used several times, while holding dust or dirt collected from a cleaning surface to be cleaned. 
     The cleaning sheet B 100  defines a prescribed cleaning sheet first direction B 100   y  and a cleaning sheet second direction B 100   x  crossing the cleaning sheet first direction B 100   y.  A longitudinal direction of the cleaning sheet B 100  coincides with the cleaning sheet first direction B 100   y.    
     The holding region B 110  extends in the cleaning sheet first direction B 100   y.  Further, in the cleaning sheet first direction B 100   y,  a direction in which the holder C 100  is attached to the cleaning sheet B 100  defines an inserting direction B 100   y   1  and a direction in which the holder C 100  is removed from the cleaning sheet B 100  defines a removing direction B 100   y   2 . 
     An extending direction of the holder C 100  is defined by an extending direction of the cleaning sheet B 100  when the holder C 100  is attached to the cleaning sheet B 100 . Specifically, a long part C 110  of the holder C 100  is inserted into a receiving part B 600  of the cleaning sheet B 100  and extends in the cleaning sheet first direction B 100   y.  Further detailed structures of the cleaning sheet B 100  and the holder C 100  are described below. 
     (Description of the Holder) 
     The holder C 100  is now described with reference to  FIG. 2 .  FIG. 2  is a plan view showing the entire holder C 100 . 
     As shown in  FIG. 2 , the holder C 100  has the long part C 110  which is attached to the holding region B 110  of the cleaning sheet B 100 , and a handle C 160  configured to be held by a user. The long part C 110  has a front end part C 120 , a base part C 130  and an extending part C 140  extending between the front end part C 120  and the base part C 130 . The extending part C 140  has a bifurcated form extending from the base part C 130 . It means that the long part C 110  has the single base part C 130  and has two extending parts C 140  and two front end parts C 120 . The handle C 160  has a front end part C 161 , a rear end part C 162  and a grip C 163  extending between the front end part C 161  and the rear end part C 162 . The base part C 130  of the long part C 110  and the front end part C 161  of the handle C 160  are configured to be removable from each other. The long part C 110  and the grip C 163  are example embodiments that correspond to the “long part” and the “grip”, respectively, according to the present invention. The holder C 100  is formed of resin material. 
     (Description of the Cleaning Sheet) 
     A basic structure of the cleaning sheet B 100  is explained with reference to  FIGS. 3 to 5 .  FIG. 3  is a plan view showing the cleaning sheet B 100 ,  FIG. 4  is a bottom view showing the cleaning sheet B 100 , and  FIG. 5  is a sectional view taken along line II-II in  FIG. 3 . 
     First, an overall structure of the cleaning sheet B 100  is explained with reference to  FIG. 5 . 
     As shown in  FIG. 5 , the cleaning sheet B 100  mainly includes a sheet-like member and a fiber bundle B 400 . The sheet-like member refers to a first sheet B 210 , a second sheet B 220  and a third sheet B 230 . Particularly the first sheet B 210  and the second sheet B 220  form a sheet element for forming the receiving part B 600 . The first sheet B 210  and the second sheet B 220  are an example embodiment that corresponds to the “sheet element” according to the present invention. 
     The first sheet B 210  and the second sheet B 220  are superposed one on the other. The fiber bundle B 400  is disposed between the second sheet B 220  and the third sheet B 230 . 
     As shown in  FIG. 5 , the first sheet B 210 , the second sheet B 220 , the fiber bundle B 400  and the third sheet B 230  are bonded together by a first bonding part B 710 . Further, the first sheet B 210 , the second sheet B 220  and part of the fiber bundle B 400  are bonded together by a second bonding part B 720 . The holding region B 110  is formed in a region surrounded by the second bonding part B 720  between the first sheet B 210  and the second sheet B 220 . In this sense, it can be said that the first bonding part B 710  forms a dividing part for dividing the holding region B 110 . The first bonding part B 710  is an example embodiment that corresponds to the “bonding part” according to the present invention. 
     In other words, a laminate sheet formed by superposing the first and second sheets B 210 , B 220  one on the other is bonded by a pair of second bonding parts B 720 . Further, the second bonding parts B 720  are arranged apart from each other. The pair second bonding parts B 720  are example embodiments that correspond to the “first sheet bonding part” and the “second sheet bonding part” according to the present invention. Thus, it can be said that the receiving part B 600  is defined by a space surrounded by the first sheet B 210 , the second sheet B 220  and the pair second bonding parts B 720 . The receiving part B 600 , the first sheet B 210  and the second sheet B 220  are example embodiments that correspond to the “receiving part”, the “first sheet-like member” and the “second sheet-like member”, respectively, according to the present invention. Further, the receiving part B 600  is divided by the first bonding part B 710 . 
     The cleaning region B 120  includes both end regions of the first sheet B 210  and the second sheet B 220  in the cleaning sheet first direction B 100   y,  both end regions of the first sheet B 210  and the second sheet B 220  in the cleaning sheet second direction B 100   x,  the fiber bundle B 400  and the third sheet B 230 . Particularly, the fiber bundle B 400  and the third sheet B 230  form a brush part B 500  which is held in contact with a region to be cleaned by a user during cleaning operation. The third sheet B 230  and the fiber bundle B 400  are example embodiments that correspond to the “cleaning side sheet-like member” and the “fiber bundle”, respectively, according to the present invention. 
     Further, the cleaning sheet B 100  according to the first embodiment has the brush part B 500  only on the second sheet B 220  side. However, the brush part B 500  may be formed on both sides of the receiving part B 600  by bonding the fiber bundle B 400  on both the first sheet B 210  side and the second sheet B 220  side. 
     As shown in  FIG. 3 , the receiving part B 600  has openings B 610  on its both ends. The long part C 110  of the holder C 100  can be inserted from either of the openings B 610 . As shown in  FIG. 3 , the first sheet B 210  is formed to be shorter than the second sheet B 220  in the cleaning sheet first direction B 100   y.  The first and second sheets B 210 , B 220  have a plurality of cuts B 331  extending in the cleaning sheet second direction B 100   x.  Further, as shown in  FIG. 4 , the third sheet B 230  also has a plurality of cuts B 331  extending in the cleaning sheet second direction B 100   x.  Strips B 310  are formed between the adjacent cuts B 331  in the first, second and third sheets B 210 , B 220 , B 230 . The strips B 310  are brought in contact with the object to be cleaned by the user so as to perform a function of scraping dust. 
     In other words, as shown in  FIGS. 3 and 4 , each of the first, second and third sheets B 210 , B 220 , B 230  has a cut element B 330  and a strip element B 300  defined by the cut element B 330 . It can be said that the cut element B 330  consists of a plurality of the cuts B 331  and the strip element B 300  is formed between adjacent ones of the cuts B 331 . With this structure, the strip element B 300  consists of a plurality of the strips B 310 . 
     The cut element B 330 , the strip element B 300  and the cut B 331  are example embodiments that correspond to the “cut element”, the “strip element” and the “cut”, respectively, according to the present invention. 
     The first, second and third sheets B 210 , B 220 , B 230  are formed of flexible nonwoven fabric or other similar materials. The first, second and third sheets B 210 , B 220 , B 230  which are welded by the bonding parts B 710 , B 720  are preferably formed of nonwoven fabric of thermal melting fibers (thermoplastic fibers). Next, structures of the first, second and third sheets B 210 , B 220 , B 230  are explained. 
     The first and second sheets B 210 , B 220  may be formed of any material having a sufficient strength for use, such as nonwoven fabric, resin film and cloth containing synthetic fibers. Particularly, in terms of the strength, through-air nonwoven fabric is preferably used which has a basis weight of 10 to 100 gsm and is formed of conjugated fibers having a core of polyethylene terephthalate and a sheath of polyethylene. 
     The third sheet B 230  may be formed of any material having a sufficient strength for use, such as nonwoven fabric, resin film and cloth containing synthetic fibers. When the third sheet B 230  is formed of nonwoven fabric, particularly in terms of the strength, through-air nonwoven fabric is preferably used which has a basis weight of under 30 gsm and is formed of conjugated fibers having a core of polyethylene terephthalate and a sheath of polyethylene. In this case, the third sheet B 230  is preferably formed to have a lighter basis weight than the first and second sheets B 210 , B 220 . With such a structure, the third sheet B 230  can be formed to be lighter and more flexible than the first and second sheets B 210 , B 220 . As a result, as described below, the strips B 310  of the third sheet B 230  can be satisfactorily raised. 
     Next, structures of the third sheet B 230  and the fiber bundle B 400  are explained with reference to  FIGS. 6 and 7 .  FIG. 6  is an explanatory view showing the strip element B 300  and  FIG. 7  is an explanatory view showing the strip element and the fiber bundle. 
     As shown in  FIG. 6 , the third sheet B 230  has a strip first direction B 310   y  which is defined by a direction from the first bonding part B 710  toward a free end of the strip element B 300 , and a strip second direction B 310   x  crossing the strip first direction B 310   y.  The strip first direction B 310   y  and the strip second direction B 310   x  are example embodiments that correspond to the “first direction” and the “second direction”, respectively, according to the present invention. 
     As shown in  FIG. 6 , the strip B 310  has a connected end B 310   b  on the first bonding part B 710  side and a free end B 310   a  on the side opposite to the connected end B 310   b  in the strip first direction B 310   y.  Further, a pair of the strips B 310  which are opposed to each other on the opposite sides of the first bonding part B 710  are defined as a first strip B 321  and a second strip B 322 , respectively. The first strip B 321  and the second strip B 322  are example embodiments that correspond to the “first strip” and the “second strip”, respectively, according to the present invention. 
     When the third sheet B 230  is formed of nonwoven fabric, fibers forming the nonwoven fabric are referred to as nonwoven fabric constituent fibers B 231 . The nonwoven fabric constituent fiber B 231  is an example embodiment that corresponds to the “nonwoven fabric constituent fiber” according to the present invention. The nonwoven fabric constituent fibers B 231  are shown only in  FIG. 7  for convenience of explanation. The nonwoven fabric constituent fibers B 231  are arranged to have orientation in the strip first direction B 310   y.    
     Further, as shown in  FIG. 7 , a plurality of fiber bundle constituent fibers B 410  having prescribed orientation are arranged to form the fiber bundle B 400 . More specifically, the fiber bundle constituent fibers B 410  have orientation in the strip first direction B 310   y.  Further, as described below, the strips B 310  and the fiber bundle constituent fibers B 410  are deformed by cleaning operation. Therefore, the state in which the fiber bundle constituent fibers B 410  have orientation in the strip first direction B 310   y  refers to the state in which the strips B 310  and the fiber bundle constituent fibers B 410  are not yet moved or deformed, or the state of the fiber bundle constituent fibers B 410  in design. The fiber bundle constituent fiber B 410  is an example embodiment that corresponds to the “fiber bundle constituent fiber” according to the present invention. 
     The fiber bundle constituent fiber B 410  has a connected end B 410   b  on the first bonding part B 710  side and a free end B 410   a  on the side opposite to the connected end B 410   b.    
     The fiber bundle constituent fiber B 410  represents a structure formed of “fibers”. In this invention, the “fibers” include a typical single fiber, and typical fibers aligned in the length direction and/or the radial direction (twist yarn, spun yarn, yarn to which a plurality of filaments are partially connected). The “typical fibers” as used herein are components of yarn, textile or the like and thin and flexible fibers having a substantially longer length compared with the thickness. Specifically, a long continuous fiber is defined as a filament and a short fiber as a staple. With this structure, the fiber bundle constituent fibers B 410  have flexibility. 
     More specifically, the fiber bundle B 400  is an assembly of the fiber bundle constituent fibers B 410  which are manufactured from polyethylene, polypropylene, polyethylene terephthalate, nylon, rayon or the like. Generally, a so-called tow can be used as the fiber bundle constituent fibers B 410 . In this case, it is preferred that the fiber bundle constituent fibers B 410  have a fineness of 0.5 to 66 dtex and are crimped fibers having 5 to 30 crimps per inch. It is further preferred that the fiber bundle constituent fibers B 410  are conjugated fibers having a core of polyethylene terephthalate and a core covering sheath of polyethylene. 
     Further, in order to enhance the dust collecting function, liquid paraffin is applied to the fiber bundle B 400 . 
     As shown in  FIG. 7 , the third sheet B 230  has a first surface B 311  facing the fiber bundle B 400  and a second surface B 312  on the side opposite to the first surface B 311 . The first surface B 311  and the second surface B 312  are example embodiments that correspond to the “first surface” and the “second surface”, respectively, according to the present invention. As described above, the fiber bundle constituent fibers B 410  and the strips B 310  are flexible. Therefore, the fiber bundle constituent fibers B 410  and the strips B 310  are configured to be bent along the first bonding part B 710  so as to be raised up in a direction away from the holding region B 110 . 
     As shown in  FIG. 7 , the strips B 310  each have a first engagement part B 311   a  formed on the first surface B 311  and a second engagement part B 312   a  formed on the second surface B 312 . The first engagement part B 311   a  and the second engagement part B 312   a  are example embodiments that correspond to the “first engagement part” and the “second engagement part”, respectively, according to the present invention. 
     The first engagement part B 311   a  is formed by the nonwoven fabric constituent fibers B 231  exposed to the first surface B 311 , and the second engagement part B 312   a  is formed by the nonwoven fabric constituent fibers B 231  exposed to the second surface B 312 . 
     Then, operation of the cleaning tool A 100  according to the first embodiment of the present invention is explained with reference to  FIG. 8 . In use of the cleaning tool A 100 , a user raises the strips B 310  and the fiber bundle constituent fibers B 410  of the cleaning sheet B 100 . For this purpose, for example, the user holds both ends of the cleaning sheet B 100  in the cleaning sheet first direction B 100   y  with both hands and alternately moves the ends up and down, and thereafter attaches the holder C 100  to the cleaning sheet B 100 . Alternatively, the cleaning sheet B 100  can also be raised by shaking up and down the user&#39;s hand holding the grip C 163  of the holder C 100  attached to the cleaning sheet B 100 . 
       FIG. 8  shows the raised state of the strips B 310  and the fiber bundle constituent fibers B 410 . Further, for the sake of explanation, only the first strip B 321 , the second strip B 322  and part of the fiber bundle constituent fibers B 410  are shown in  FIG. 8 . 
     When the first strip B 321  and the second strip B 322  are raised, the first engagement part B 311   a  is engaged with the fiber bundle constituent fibers B 410 . At this time, the first engagement part B 311   a  and the fiber bundle constituent fibers B 410  are required only to be partially engaged with each other, but not to be wholly engaged with each other. 
     Further, the second engagement part B 312   a  of the first strip B 321  and the second engagement part B 312   a  of the second strip B 322  are engaged with each other. At this time, the second engagement parts B 312   a  of the two strips B 310  are required only to be partially engaged with each other, but not to be wholly engaged with each other. 
     In the cleaning tool A 100  according to the first embodiment of the present invention, when the strips B 310  and the fiber bundle constituent fibers B 410  are raised, the strips B 310  and the fiber bundle constituent fibers B 410  are engaged with each other and the strips B 310  are engaged with each other. Therefore, the strips B 310  and the fiber bundle constituent fibers B 410  which form the brush part B 500  can be efficiently raised. As a result, particularly in an early stage of a cleaning operation, a space for capturing dust can be suitably secured between the strips B 310  and the fiber bundle constituent fibers B 410 . Further, the volume of the brush part B 500  is increased in appearance, which can provide the user with higher expectations for efficient cleaning operation. 
     (Description of Preferable Third Sheet) 
     Inventors have confirmed that a preferable structure of the nonwoven fabric forming the third sheet B 230  includes the following physical properties in order to raise the strips B 310  and the fiber bundle constituent fibers B 410  as described above. Further, the nonwoven fabric constituent fibers B 231  preferably have orientation in the strip first direction B 310   y.    
     In order to raise the third sheet B 230 , it is preferred that the nonwoven fabric has low rigidity. Specifically, the third sheet B 230  is preferably formed of nonwoven fabric having rigidity of 69.7 to 80.0 mm in the first direction and rigidity of 35.0 to 39.9 mm in the second direction. Further, the rigidity is measured according to JIS L 8.21 bending resistance (cantilever A method). Thus, it is preferred that the third sheet B 230  has higher rigidity in the first direction than in the second direction. 
     In order to form the first and second engagement parts B 311   a,  B 312   a,  it is necessary to appropriately arrange the nonwoven fabric constituent fibers B 231  on the first and second surfaces B 311 , B 312 . This structure can be achieved by increasing the distance between the nonwoven fabric constituent fibers B 231  adjacent to each other. This increase means that the total light transmittance of the nonwoven fabric increases. 
     Specifically, the total light transmittance of the third sheet B 230  is preferably 80% or more. More specifically, it is preferred that the third sheet B 230  is formed of nonwoven fabric having a total light transmittance of 83.03 to 88.43%. Further, the total light transmittance is measured in accordance with JIS-K7105. More specifically, it was measured by a color difference meter Z-300A of light irradiation photometric system of Nippon Denshoku Industries Co., Ltd. domiciled at 4-45-17 Sengoku, Bunkyo-ku, Tokyo, Japan. 
     In view of the functions exhibited by the first and second engagement parts B 311   a,  B 312   a,  it is preferred that an average friction coefficient of the second surface B 312  in the strip first direction B 310   y  is larger than that of the first surface B 311  in the strip second direction B 310   x.  With this structure, the strips B 310  can be engaged with each other in a satisfactory manner. Specifically, the fiber bundle constituent fibers B 410  engage with the strips B 310  which are engaged with each other in a satisfactory manner, so that the reliability of raising the strips B 310  and the fiber bundle constituent fibers B 410  is improved. 
     Further, in order to prevent the strips B 310  engaged with each other from being displaced from each other in the cleaning sheet first direction B 100   y,  it is preferred that an average surface friction coefficient of the second surface B 312  in the strip second direction B 310   x  is larger than that of the first surface B 311  in the strip second direction B 310   x.    
     In this sense, the third sheet B 230  is preferably formed of nonwoven fabric having an average surface friction coefficient of 0.126 to 0.129μ in the strip first direction B 310   y  on the first surface B 311  and an average surface friction coefficient of 0.138 to 0.145μ in the strip first direction B 310   y  on the second surface B 312 . 
     Further, the third sheet B 230  is preferably formed of nonwoven fabric having an average surface friction coefficient of 0.136 to 0.137μ in the strip second direction B 310   x  on the first surface B 311  and an average surface friction coefficient of 0.145 to 0.163μ in the strip second direction B 310   x  on the second surface B 312 . 
     Further, the average surface friction coefficient was evaluated by using KES-FB4 of Kato Tech Co., Ltd. domiciled at 26 Karato-cho, Nishikujo, Minami-ku, Kyoto, Japan. The measurement was conducted on a sample of nonwoven fabric having a size of 100 mm×100 mm under a tension of 400 g, a friction static load of 50 g and a roughness static load of 10 g at a standard speed of 1 mm per second. 
     In order to improve the reliability of engagement between the strips B 310  and the fiber bundle constituent fibers B 410  and between the strips B 310 , it is preferred that the third sheet B 230  has a rough surface. In this sense, it is preferred that the third sheet B 230  is a nonwoven fabric having an average deviation of surface roughness of 3.225 to 3.350μ in the strip first direction B 310   y  on the first surface B 311  and having an average deviation of surface roughness of 3.250 to 3.535μ in the strip first direction B 310   y  on the second surface B 312 . Thus, it is preferred that the third sheet B 230  is configured such that the average deviation of surface roughness in the strip first direction B 310   y  on the second surface B 312  is larger than that on the first surface B 311 . 
     Further, the average deviation of surface roughness was evaluated by using KES-FB4 of Kato Tech Co., Ltd. The measurement was conducted on a sample of nonwoven fabric having a size of 100 mm×100 mm under a tension of 400 g, a friction static load of 50 g and a roughness static load of 10 g at a standard speed of 1 mm per second. 
     Based on the above-mentioned conditions of a suitable nonwoven fabric for the third sheet B 230 , the cleaning sheet B 100  having the following cleaning region B 120  was prepared. 
     (Structure of the Cleaning Region B 120  in Example) 
     
         
         
           
             The nonwoven fabric constituent fibers B 231  are conjugated fibers having a core of polyethylene terephthalate and a core covering sheath of polyethylene, and has a fineness of 3.2 dtex and an average fiber length of 39 mm. 
             The nonwoven fabric has a basis weight of 20 gsm. 
             The nonwoven fabric is manufactured by through-air bonding. 
             The fiber bundle B 400  is obtained by arranging about 37,500 fiber bundle constituent fibers B 410  each having a fineness of 3.3 dtex (total fineness of about 124,000 dtex). 
           
         
       
    
     (Structure of the Cleaning Region B 120  in Comparative Example) 
     
         
         
           
             The nonwoven fabric constituent fibers B 231  are conjugated fibers having a core of polyethylene terephthalate and a core covering sheath of polyethylene. The conjugated fibers consist of 35% of fibers having a fineness of 2.2 dtex and an average fiber length of 51 mm, and 65% of fibers having a fineness of 2.8 dtex and an average fiber length of 45 mm. 
             The nonwoven fabric has a basis weight of 30 gsm. 
             The nonwoven fabric is manufactured by through-air bonding. 
             The fiber bundle B 400  is obtained by arranging about 31,250 fiber bundle constituent fibers B 410  each having a fineness of 3.5 dtex (total fineness of about 110,000 dtex). 
           
         
       
    
     In the cleaning sheet B 100  having the above-described cleaning region B 120  in the example and the cleaning sheet having the above-described cleaning region in the comparative example, the strips and the fiber bundle constituent fibers were raised under the same conditions and then the results were visually checked. As a result, it was confirmed that the cleaning sheet B 100  in the example can be more satisfactorily raised than the cleaning sheet in the comparative example. 
     Further, assuming an actual product, the size of the third sheet B 230  corresponding to seven strip sheets arranged in the strip second direction B 310   x  was set to 40 mm square. The nonwoven fabrics of the example and the comparative example were prepared in such a manner as to meet the above-described conditions, and the thicknesses of the nonwoven fabrics were measured. The measurement was conducted by using a PEACOCK measuring instrument of Ozaki Mfg. Co., Ltd. domiciled at 1-63-11 Tokiwadai, Itabashi-ku, Tokyo, Japan. The PEACOCK measuring instrument has a measuring surface having a diameter of 44 mm and the measuring pressure is 3 g/cm 2 . 
     The result showed that the nonwoven fabric of the example has a thickness of 0.315 mm and the nonwoven fabric of the comparative example has a thickness of 0.6052 mm. 
     Thus, it is confirmed that the nonwoven fabric of the example is preferably thinner than the nonwoven fabric of the comparative example. Further, the basis weight of the nonwoven fabric of the example is lower than that of the nonwoven fabric of the comparative example, so that it is confirmed that a thinner and lighter nonwoven fabric is suitable to obtain an excellent raised state of the strips B 310 . 
     Description of Second Embodiment 
     A cleaning tool A 100  according to a second embodiment of the present invention is now explained with reference to  FIG. 9 . In the cleaning tool A 100  according to the second embodiment, components or elements having the same structures and functions as those in the cleaning tool A 100  of the first embodiment are given like numerals as in the first embodiment, and they are not described here. 
     The cleaning tool A 100  of the second embodiment is different from the cleaning tool A 100  of the first embodiment in the structure of the holding region B 110 . Specifically, in the cleaning tool A 100  of the second embodiment, the receiving part B 600  is formed only by the first sheet B 210 . The first sheet B 210  is an example embodiment that corresponds to the “single sheet-like member” according to the present invention. 
     As shown in  FIG. 9 , the first sheet B 210  has a superposed part formed by superposing regions spaced apart from each other in the first sheet B 210  one on the other. The superposed regions of the first sheet B 210  are bonded by a bonding part B 730  in the superposed part. The bonding part B 730  is an example embodiment that corresponds to the “sheet bonding part” according to the present invention. With this structure, the receiving part B 600  is defined by a space surrounded by the bonding part B 730  and a region of the first sheet B 210  which extends in a loop between the spaced-apart regions bonded at the bonding part B 730 . 
     In the cleaning tool A 100  according to the second embodiment, the extending part C 140  of the holder C 100  can be attached to the receiving part B 600 . Further, the cleaning region B 120  has the same structure as that of the first embodiment, so that the same effect as the first embodiment can be obtained in raising the strips B 310  and the fiber bundle constituent fibers B 410 . 
     (Correspondences Between the Features of the Embodiments and the Features of the Invention) 
     The cleaning tool A 100  is an example embodiment that corresponds to the “cleaning tool” according to the present invention. The holder C 100  is an example embodiment that corresponds to the “holder” according to the present invention. The cleaning sheet B 100  is an example embodiment that corresponds to the “cleaning sheet” according to the present invention. The holding region B 110  is an example embodiment that corresponds to the “holding region” according to the present invention. The cleaning region B 120  is an example embodiment that corresponds to the “cleaning region” according to the present invention. The long part C 110  is an example embodiment that corresponds to the “long part” according to the present invention. The grip C 163  is an example embodiment that corresponds to the “grip” according to the present invention. The first sheet B 210  and the second sheet B 220  are an example embodiment that corresponds to the “sheet element” according to the present invention. The first bonding part B 710  is an example embodiment that corresponds to the “bonding part” according to the present invention. A pair of second bonding parts B 720  is an example embodiment that corresponds to the “first sheet bonding part” and the “second sheet bonding part” according to the present invention. The first sheet B 210  is an example embodiment that corresponds to the “first sheet-like member” according to the present invention. The second sheet B 220  is an example embodiment that corresponds to the “second sheet-like member” according to the present invention. The receiving part B 600  is an example embodiment that corresponds to the “receiving part” according to the present invention. The third sheet B 230  is an example embodiment that corresponds to the “cleaning side sheet-like member” according to the present invention. The fiber bundle B 400  is an example embodiment that corresponds to the “fiber bundle” according to the present invention. 
     The cut element B 330  is an example embodiment that corresponds to the “cut element” according to the present invention. The strip element B 300  is an example embodiment that corresponds to the “strip element” according to the present invention. The cut B 310  is an example embodiment that corresponds to the “cut” according to the present invention. The strip first direction B 310   y  is an example embodiment that corresponds to the “first direction” according to the present invention. The strip second direction B 310   x  is an example embodiment that corresponds to the “second direction” according to the present invention. The first strip B 321  is an example embodiment that corresponds to the “first strip” according to the present invention. The second strip B 322  is an example embodiment that corresponds to the “second strip” according to the present invention. The nonwoven fabric constituent fiber B 231  is an example embodiment that corresponds to the “nonwoven fabric constituent fiber” according to the present invention. The fiber bundle constituent fiber B 410  is an example embodiment that corresponds to the “fiber bundle constituent fiber” according to the present invention. The first surface B 311  is an example embodiment that corresponds to the “first surface” according to the present invention. The second surface B 312  is an example embodiment that corresponds to the “second surface” according to the present invention. The first engagement part B 311   a  is an example embodiment that corresponds to the “first engagement part” according to the present invention. The second engagement part B 312   a  is an example embodiment that corresponds to the “second engagement part” according to the present invention. The first sheet B 210  is an example embodiment that corresponds to the “single sheet-like member” according to the present invention. The bonding part B 730  is an example embodiment that corresponds to the “sheet bonding part” according to the present invention. 
     DESCRIPTION OF THE NUMERALS 
     
         
         A 100  cleaning tool 
         B 100  cleaning sheet 
         B 100   x  cleaning sheet second direction 
         B 100   y  cleaning sheet first direction 
         B 100   y   1  inserting direction 
         B 100   y   2  removing direction 
         B 110  holding region 
         B 120  cleaning region 
         B 210  first sheet (sheet element, first sheet-like member) 
         B 220  second sheet (sheet element, second sheet-like member) 
         B 230  third sheet (cleaning side sheet-like member) 
         B 231  nonwoven fabric constituent fiber 
         B 300  strip element 
         B 310  strip 
         B 310   a  free end 
         B 310   b  connected end 
         B 310   x  strip second direction (second direction) 
         B 310   y  strip first direction (first direction) 
         B 311  first surface 
         B 311   a  first engagement part 
         B 312  second surface 
         B 312   a  second engagement part 
         B 321  first strip 
         B 322  second strip 
         B 330  cut element 
         B 331  cut 
         B 400  fiber bundle 
         B 410  fiber bundle constituent fiber 
         B 410   a  free end 
         B 410   b  connected end 
         B 500  brush part 
         B 600  receiving part 
         B 610  opening 
         B 710  first bonding part (bonding part) 
         B 720  second bonding part (first sheet bonding part, second sheet bonding part) 
         B 730  bonding part (sheet bonding part) 
         C 100  holder 
         C 110  long part 
         C 120  front end part 
         C 130  base part 
         C 140  extending part 
         C 141  first extending part 
         C 142  second extending part 
         C 151  front end side projection 
         C 152  base side projection 
         C 160  handle 
         C 161  front end part 
         C 162  rear end part 
         C 163  grip