Patent Document

RELATED APPLICATIONS 
       [0001]    This is a continuation-in-part of U.S. patent application Ser. No. 10/622,763, filed Jul. 18, 2003, which is a divisional of U.S. patent application Ser. No. 09/891,034, filed on Jun. 25, 2001, both of which are hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a method for manufacturing a disposable worn article using an elastic sheet. 
         [0004]    2. Description of the Related Art 
         [0005]    Japanese Laid-Open Patent Publication No. 2000-26015 discloses a method for cutting off only an elastic member without damaging a base material sheet by using a roll cutter having a ridge-shaped blade thereon. 
         [0006]    However, Laid-Open Patent Publication No. 2000-26015 fails to disclose sealing the base material sheet while cutting off the elastic member, improving the air permeability of the base material sheet while cutting off the elastic member, etc. 
       SUMMARY OF THE INVENTION 
       [0007]    A method for manufacturing a disposable worn article of the present invention includes: a first step of applying an adhesive on at least one of a first web and a second web; a second step of sandwiching an elastic member between the first and second webs and combining the first and second webs and the elastic member together, thereby producing a combined web; and a third step of melting a portion of at least one of the first and second webs and a portion of the elastic member, thereby reducing a shrinking force of the elastic member in the melted portion. 
         [0008]    Another method for manufacturing a disposable worn article of the present invention includes: a first step of applying an adhesive on at least one of a first web and a second web; a second step of sandwiching an elastic member between the first and second webs and combining the first and second webs and the elastic member together, thereby producing a combined web; and a third step of melting a portion of at least one of the first and second webs and a portion of the elastic member, thereby cutting off the elastic member. 
         [0009]    Still another method for manufacturing a disposable worn article includes: a first step of applying an adhesive on at least one of a first web and a second web; a second step of sandwiching an elastic member between the first and second webs and combining the first and second webs and the elastic member together, thereby producing a combined web; and a third step of cutting off a portion of at least one of the first and second webs, and the elastic member. 
         [0010]    In one embodiment of the invention: the third step is performed by passing the combined web between an embossing roll having a plurality of protrusions and a counter roll; and an interval of the protrusions in a direction of a rotation axis of the embossing roll is about 1 mm to 25 mm. 
         [0011]    In another embodiment of the invention, the third step is performed by passing the combined web between an embossing roll having a lattice portion and a counter roll. 
         [0012]    In still another embodiment of the invention, a first charge is applied to an area of at least one of the first and second webs where the adhesive is to be applied, and a second charge different from the first charge is applied to the adhesive to be applied. 
         [0013]    In still another embodiment of the invention: at least the first web includes a design area having at least one of a graphical design, a symbol and a character printed thereon; and the elastic member located on at least a portion of the design area is cut off in the third step. 
         [0014]    In still another embodiment of the invention: at least the second web includes an area on which a member is to be adhered; and the elastic member located under at least a portion of the area is cut off in the third step. 
         [0015]    In still another embodiment of the invention, the elastic member is at least one of a string rubber, a flat rubber and a meshed rubber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view illustrating one embodiment of the method of the present invention. 
           [0017]    Each of  FIG. 2A ,  FIG. 2B  and  FIG. 2C  is a diagram illustrating an example of a disposable worn article using a combined web. 
           [0018]    Each of  FIG. 3A  and  FIG. 3B  is a diagram illustrating an example of a staggered emboss pattern. 
           [0019]      FIG. 4  is a diagram illustrating how elastic members are cut off. 
           [0020]      FIG. 5  is a diagram illustrating how elastic members are cut off. 
           [0021]      FIG. 6  is a diagram illustrating an example of a lattice emboss pattern. 
           [0022]      FIG. 7A  is a diagram illustrating an example of an adhesive applicator, and each of  FIG. 7B  and  FIG. 7C  is a diagram illustrating an example of a conductive portion thereof. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    A first embodiment of the present invention will now be described with reference to the accompanying drawings. 
         [0024]      FIG. 1  is a diagram illustrating a manufacturing apparatus  1  for manufacturing a disposable worn article according to the first embodiment. 
         [0025]    The manufacturing apparatus  1  includes an adhesive applicator  13  for applying an adhesive on a first sheet  10 , a guide  21  for guiding an elastic member  20  between the first sheet  10  and a second sheet  30 , press rolls  31  and  32  for pressing together the first sheet  10  and the second sheet  30  into a combined web  40 , and a processing section  2  for cutting off at least a part of, or reducing the shrinking force of, the elastic member  20  of the combined web  40  produced through the press rolls  31  and  32 . The adhesive may be applied on the second sheet  30 . 
         [0026]    The adhesive applicator  13  is capable of applying an adhesive on the first sheet  10 , which has a strip shape of a predetermined width and which is advanced in the X direction (the direction of the production flow), so that an adhesive portion  11  and a non-adhesive portion  12  are provided on the first sheet  10 . In terms of the air permeability of the combined web  40 , it is preferred that the adhesive applicator  13  is a spray coater, a curtain coater, a spiral coater, or the like. The amount of adhesive is preferably about 1 g/m 2  to about 20 g/m 2 . The adhesive may be a hot melt. A specific example of the adhesive applicator  13  will be described later. 
         [0027]    The elastic member  20  under a predetermined tension is supplied to the guide  21 . The elastic member  20  may be in the form of a plurality of lines, as illustrated in  FIG. 1 , or a mesh (e.g., elastomeric netting such as REBOUND® of CONWED PLASTICS may be used). The elastic member  20  may be a string rubber or a flat rubber. The guide  21  is capable of reciprocating transversely of the direction of the production flow. In such a case, the guide  21  is capable of guiding the elastic member  20  between the first sheet  10  and the second sheet  30  so that the elastic member  20  is drawn in a non-linear line. A predetermined tension is applied to the elastic member  20  supplied to the guide  21  by means of a tension roll (not shown). 
         [0028]    The processing section  2  includes an embossing roll  50  and a counter roll  60  facing the embossing roll  50 . The combined web  40  is inserted between the embossing roll  50  and the counter roll  60 , and the processing section  2  cuts off at least a part of, or reduces the shrinking force of, the elastic member  20 . The embossing roll  50  includes an embossing section  51  having a plurality of protrusions. The protrusions may generate heat as will be described later. In such a case, the amount of heat to be generated is determined by the distance between the embossing roll  50  and the counter roll  60 , the shape and/or the size of each protrusion, the material, the cross-sectional area and/or the shape of the elastic member  20 , and/or the speed at which the combined web  40  is advanced. 
         [0029]      FIG. 2(A)  to  FIG. 2(C)  are plan views illustrating an exemplary disposable worn article made of the combined web  40 , which has been passed through the processing section  2 . The disposable worn articles illustrated in  FIG. 2(A)  to  FIG. 2(C)  (e.g., disposable underpants or disposable diapers; hereinafter referred to simply as “underpants”) include a design area  150  having a graphical design or characters (a picture of a bear in the illustrated example, which is not shown in  FIG. 2(A)  and  FIG. 2(C) ) printed thereon. If the shrinking force of a part of the elastic member  20  on the design area  150  is not reduced or eliminated, the design area  150  will be wrinkled by the shrinking force, thereby making the bear not look like a bear and deteriorating the appearance. If the shrinking force of a part of the elastic member  20  on the design area  150  is reduced or eliminated, the bear can be perceived as a bear as shown in the underpants  130  of  FIG. 2(A) , thus making the underpants aesthetic. 
         [0030]    Also in cases where a label having a graphical design or characters printed thereon is attached to the combined web  40 , the label will have wrinkles due to the shrinkage of the elastic member  20 , thereby deteriorating the appearance. Besides, such wrinkles make it difficult to adhere, on the combined web  40 , a member such as a label, a tape used for fixing a diaper, a tape used when disposing of the article having the combined web  40 , etc. Even if the combined web  40  and the other member are successfully adhere together while the wrinkles are being smoothed out, it is difficult to keep the adhesion between the combined web  40  and the other member for a long period of time due to the shrinkage of the elastic member  20 . 
         [0031]    The underpants  130  of  FIG. 2(A)  include the adhesive portion  11  and the non-adhesive portion  12  which has substantially the same width as that of the design area  150 , and the part of the elastic member  20  on the design area  150  is cut off. Reference numeral  42  denotes sealing lines or slits occurring when cutting off the elastic member  20 . The shrinkage of the cut elastic member  20  stops in the vicinity of the boundary between the adhesive portion  11  and the non-adhesive portion  12 . Where the combined web  40  has the non-adhesive portion  12 , it is preferred that the embossing section  51  of the embossing roll  50  has at least two rows of protrusions such that the rows of protrusions are spaced apart from each other in the direction of the rotation of the embossing roll  50  and such that a protrusion of the second row is located between a pair of adjacent protrusions of the first row, as shown in  FIG. 3(A) , for example, in order to eliminate the shrinking force of the elastic member  20  on the design area  150 . In  FIG. 2(A) , the elastic member  20  is cut off by the embossing section  51  having two rows of protrusions, and the sealing lines (or slits where the second web  30  is also cut off)  42  are formed during the cutting process. Even with a single row of protrusions, the elastic member  20  can be cut off if the protrusions are arranged so as to overlap with one another in a slant direction, for example. In other words, it is only required that when the protrusions are projected in the direction of the rotation of the embossing roll  50 , end portions of projection lines of adjacent protrusions overlap with each other. Alternatively, for example, cutting off, etc., of a plurality of elastic members  20  can be achieved with a single protrusion. The length L 2  of the embossing section  51  may be slightly smaller than the length L 1  of the non-adhesive portion  12 . 
         [0032]    The protrusions of the embossing roll  50  may generate heat in order to eliminate the shrinking force of the elastic member  20 . The elastic member  20  is cut off by the protrusions temporarily melting at least a part of the second web  30  and apart of the elastic member  20 . Then, with the temporary melting of the second web, the first web  10  and the second web  30  are fused together. For example, in the case of the underpants  130 , the first web  10  and the second web  30  are sealed together to form the sealing line  42 , while the elastic member  20  is cut off. The wrinkling in the design area  150  is improved when the shrinking force of the elastic member  20  is reduced, even if the elastic member  20  is not cut off completely. 
         [0033]    Even if the protrusions do not generate heat, it is possible to cut off the elastic member  20  via the second web  30  when the width of each protrusion is small. In this process, at least a part of the second web  30  is also cut off (the part abutting the protrusions), thus making the slits  42  in the second web  30 . 
         [0034]    In the underpants  140  of  FIG. 2(B) , an adhesive is applied also in the design area  150 . In order to eliminate the shrinking force of the part of the elastic member  20  on the design area  150 , it is preferred to cut off, for example, the part of the elastic member  20  located on the design area  150  at a predetermined interval. By performing a process such as the cutting off at a predetermined interval, the appearance of the design area  150  will be even. Therefore, it is preferred that the protrusions in each row are arranged at a predetermined interval in the embossing section  51 . If the slits  42  are provided not only in the label area  41  but also in a waist section  151  and a crotch section  152 , the air permeability is improved. 
         [0035]    Moreover, the elastic member  20  is located under the second web  30 . Therefore, when fixing another additional member (e.g., a tape used for disposing of underpants, a fastening tape for fastening the article into a underpants shape, a label, etc.) is fixed on the second web  30 , the shrinking force of the part of the elastic member  20  present in the fixing position may be eliminated in advance through the processing section  2 . This is because it is difficult to fix such a member on the second web  30  while the underpants are shrunk due to the shrinking force of the elastic member  20 . 
         [0036]    The underpants  160  of  FIG. 2(C)  are made of the combined web  40  having the meshed elastic member  20  sandwiched between the first web  10  and the second web  30 . In a waist area  161 , it is preferred that the vertical elastic strings are cut off while leaving the horizontal elastic strings so that the underpants  160  fit well to the body of the wearer. If another additional member is bonded to a section indicated by reference numeral  162 , for example, the vertical and horizontal elastic strings are cut off in the section  162 . Moreover, also in a predetermined crotch section  163 , the vertical and horizontal elastic strings are cut off. The predetermined section  163  is an area where it is preferred that the underpants  160  do not shrink. It is preferred that an absorbent is provided in such an area. 
         [0037]    As described above, it is made possible to adhere a member on the combined web  40  by reducing the shrinking force of the elastic member  20  of the combined web  40  in areas where the member is to be adhered. Possible methods for reducing or eliminating the shrinking force of the elastic member  20  include: cutting off the elastic member  20 ; reducing the shrinking force of the elastic member  20 ; altering the molecular structure of the elastic member  20  (when the elastic member  20  is a rubber), and melting a part of the combined web  40  and curing the melted part. 
         [0038]    The protrusions may generate heat in order to reduce or eliminate the shrinking force of the elastic member. In such a case, the elastic member  20  is cut off by the protrusions melting at least a part of the second sheet  30  and at least apart of the elastic member  20 . In this process, the first sheet and the second sheet are sealed together. For example, in the case of the underpants  130 , the first sheet and the second sheet are sealed together while the elastic member  20  is cut off. The wrinkling of the elastic member  20  is improved when the shrinking force of the elastic member  20  is reduced, even if the elastic member  20  is not cut off. 
         [0039]    Moreover, even if the protrusions do not generate heat, it is possible to cut off the elastic member  20  via the second sheet  30  when the width of each protrusion is small (e.g., several microns to about 0.5 mm). In this process, at least a part of the second sheet  30  is cut by the protrusions, thereby increasing the air permeability of the underpants  140 . In addition to the design area  150 , a part of the elastic member  20  corresponding to an upper waist area  151  and/or a leg area  152  of the underpants  140  may also be opened by the protrusions. 
         [0040]    The protrusions of the embossing section  51  will now be described.  FIG. 3A  illustrates an emboss pattern including a plurality of rectangular protrusions arranged in a staggered pattern. The embossing section  51  includes: an n−1 th  row of rectangular protrusions  53 ,  53  each having a length S 1  and a width W 1  which are arranged in the axial direction of the embossing roll  50  (indicated by a solid arrow) at intervals of a distance D 1 ; an n th  row of protrusions  54 ,  54  each having the same length (S 1 ) and width (W 1 ) as those of the protrusions  53  which are arranged in the circumferential direction of the embossing roll  50  (indicated by an outline arrow) at a distance of M 1  from the protrusions  53  so that the longitudinal center line thereof passes through a point of D 1 /2; and an n+1 th  row of protrusions  55 ,  55  having the same shape as that of the protrusions  53  which are arranged in the same manner as the protrusions  53 . The number of protrusions in each row may be determined based on, for example, the number of elastic members to be cut off. The number of rows of protrusions may be determined based on the length L 1  of the non-adhesive portion. Herein, n is a natural number, and “0 row” means there is no row of protrusions. 
         [0041]    In an alternative emboss pattern where n is a natural number equal to or greater than 2, a protrusion in the n−1 th  row may overlap with the protrusion in the n+1 th  row in the row direction by at least 1 mm or more. In such a case, a protrusion in the n−1 th  row may not overlap with the protrusion in the n th  row or may overlap with the protrusion in the n th  row by about 0.5 mm to about 1 mm. In this way, the density of protrusions in each row may be reduced as compared to the emboss pattern illustrated in  FIG. 3A , thereby facilitating the production of the emboss roll. 
         [0042]    With an emboss roll having such protrusions as described above, as compared to an emboss roll having a single line blade, the protrusions more easily cut into the combined web, whereby it is possible to easily cut off the elastic member. 
         [0043]      FIG. 3B  shows a pattern in which diamond-shaped protrusions are arranged in a staggered pattern. The embossing section  51  includes: a row of diamond-shaped protrusions  56 ,  56  each having a long axis S 2  and a short axis W 2  which are arranged in the axial direction of the embossing roll  50  (indicated by a solid arrow) at intervals of a distance D 2 ; another row of protrusions  57 ,  57  each having the same diamond shape as the protrusions  56  which are arranged in the circumferential direction of the embossing roll  50  (indicated by an outline arrow) at a distance of M 2  from the protrusions  56  so that the short axis thereof is collinear with a point of D 2 /2; and still another row of protrusions  58 ,  58  each having the same shape as that of the protrusions  56  which are arranged in the same manner as the protrusions  56 . Of course, also for this pattern, the number of protrusions in each row may be determined based on, for example, the number of elastic members to be cut off, and the number of rows of protrusions may be determined based on the length L 1  of the non-adhesive portion. 
         [0044]    The length S 1  of the rectangular protrusions and the length of the long axis S 2  of the diamond-shaped protrusions are both preferably in the range of 1 mm to 25 mm, and more preferably 2 mm to 25 mm. Where the interval D 1  between adjacent protrusions is less than or equal to S 1 , the elastic member located between adjacent protrusions  53  can be reliably cut off by the protrusion  54  due to the staggered arrangement. Similarly, D 2  and S 2  may be determined so that D 2 S 2  holds. When S 1  or S 2  is less than 1 mm, the embossing section  51  may fail to cut off the elastic member, and when it is greater than 25 mm, the feel/touch of the article may deteriorate due to the excessive total area of seal portions. D 1  and D 2  are also preferably in the range of 1 mm to 25 mm, and D 1  is more preferably 2 mm to 25 mm. Where diamond-shaped protrusions are used, if a protrusion in a row has little overlap with the closest protrusion in an adjacent row in the row direction, the elastic member may fall between adjacent seal portions, and the embossing section  51  may thereby fail to cut off the elastic member, depending upon the arrangement of the protrusions. In view of this, D 2  is more preferably 3 mm to 10 mm. 
         [0045]    When a portion of the combined web is to be melted, the width W 1  of the rectangular protrusions and the length of the short axis W 2  of the diamond-shaped protrusions are preferably 0.5 mm to 15 mm. When the first sheet  10  and the elastic member are cut off, W 1  is preferably several microns to about 0.5 mm. When they are greater than 15 mm, the feel/touch of the manufactured article may deteriorate due to the excessive total area of seal portions. The lower limit of W 2  is preferably 1 mm or more. 
         [0046]    While the distance between adjacent rows of protrusions is not limited to any particular value, M 1  or M 2  is preferably 1 mm to 25 mm. The protrusions may have a shape other than a rectangular shape and a diamond shape as described above, including a slanted rectangular shape, a circular shape, a triangular shape, a star shape, a heart shape, a clover shape, a crescent shape, other polygons, etc. The shape of the protrusions may be varied for different rows. 
         [0047]      FIG. 4  schematically illustrates elastic members  22  and  23  having been cut off. It is assumed that the combined web is advanced downwardly in  FIG. 4 . The area  11  is the adhesive portion and the area  12  is the non-adhesive portion. The left-hand side elastic member  22  is cut off by a seal portion  70  (corresponding to the protrusion  53 ). An end portion  22   a  of the elastic member  22  is released from the tension and shrink toward the elastic member  22  bonded on the sheet. If the remaining part of the elastic member is caught by the protrusion  55  before completion of the cutting off by the protrusion  53 , an elastic member  22   b  between the protrusion  53  and the protrusion  55  shrinks toward a seal portion  72  when the elastic member is cut off by the protrusion  53 . If the cutting off by the protrusion  53  is completed before the remaining part of the elastic member is caught by the protrusion  55 , the elastic member  22   b  will shrink toward the elastic member existing in the downstream adhesive portion (not shown). The right-hand side elastic member  23  is cut off by a seal portion  71  (corresponding to the protrusion  54 ), and an end portion  23   a  thereof shrinks. 
         [0048]    With the arrangement described above, the elastic member is cut off and a large number of small seal portions are formed in the non-adhesive portion, whereby the upper and lower sheets are bonded together also in the non-adhesive portion. Since the seal portions are separated from one another and each have a small size, they are less likely to give discomfort to the wearer than when they are provided as a continuous line even when they are heat-sealed into a film. 
         [0049]    An exemplary adhesive applicator will now be described. 
         [0050]      FIG. 7A  is a diagram illustrating an exemplary adhesive applicator  13   a.  The adhesive applicator  13   a  includes a gun member  100  for spraying an adhesive (a hot melt in the following description) while positively charging the hot melt, and a conductive member  101  which is located under the first sheet  10  and is grounded or negatively charged. Generally, not all of the hot melt sprayed from the gun member  100  is attached to the sheet, but a portion thereof is left floating in the air. However, by charging the hot melt as described above, it is possible to efficiently attach the hot melt to the sheet, and to reduce the amount of hot melt to be scattered with respect to the width direction of the sheet, thereby improving the widthwise precision. A voltage of the same polarity as the hot melt may be applied to portions where it is not necessary to apply the hot melt. 
         [0051]    It is possible to improve the positional precision of the attachment of the hot melt in the flow direction, which is transverse to the width direction, by controlling the period in which the hot melt is output and the potential of the gun member  100  or the conductive member  101 . The polarities of the applied voltages may be reversed from that described above. 
         [0052]    The conductive member  101  may be provided in the form of a plurality of plates  101   a  and  101   b  as illustrated in  FIG. 7B . For example, when the hot melt is applied on areas separated by a predetermined interval by using a plurality of gun members  100 , the hot melt application may be performed with the interval between adjacent hot melt-applied areas being the interval between the plates  101   a  and  101   b.    
         [0053]    Alternatively, the conductive member  101  may be provided in the form of a roller  102  as illustrated in  FIG. 7C . The roller  102  rotates in synchronism with the first sheet  10 . The roller  102  includes a conductive portion  103  and a non-conductive portion  104 . As described above, the hot melt is charged to a potential of the first polarity, and the conductive portion  103  is grounded or charged to a potential of the opposite polarity to the first polarity. 
         [0054]    The shape of the conductive portion  103  is determined based on the shape of the area of the first sheet  10  on which the hot melt is to be applied. The gun member  100  is controlled to output the hot melt a predetermined time before the leading edge of the area on which the hot melt is to be applied passes by the gun member  100 , and to stop outputting the hot melt a predetermined time before the trailing edge of the area on which the hot melt is to be applied passes by the gun member  100 . With such an arrangement, it is possible to attach the hot melt to an area substantially equal to the intended area on which the hot melt should be applied. The roller  102  may be positioned upstream of the gun member  100 . 
         [0055]    It is understood that the adhesive applicator as described above may be used for manufacturing articles other than disposable worn articles. Nothing may be sandwiched between the first sheet and second sheet after the application of the hot melt, or a member other than the web materials may be adhered by the hot melt after the application of the hot melt. 
         [0056]    The hot melt adhesive may be continuously applied without providing a non-adhesive portion. This may be a more preferred embodiment than when the adhesive portions and the non-adhesive portions are alternately provided, because it is possible, in the former embodiment, to further increase the production line speed. The elastic member may be sandwiched between sheets on which an adhesive has been continuously applied and then passed between the embossing roll and the counter roll, so as to cut off only the elastic member without cutting off the sheets. After the cutting process, each elastic member  24  is held by two (or three or more) seal portions  59  and  59 , as illustrated in  FIG. 5 , while being relaxed. Therefore, even when the coating of the hot melt adhesive is continuous, the seal portion can be made non-elastic by changing the type and/or amount of the hot melt adhesive and/or the spraying direction thereof. It is believed that where the elastic member is cut off by heat, the hot melt adhesive is re-melted and softened by the heat of the embossing roll, so that the anchoring force on the elastic member by the hot melt adhesive is reduced and the elastic recovering force of the elastic member overcomes the anchoring force, whereby the elastic member is bonded to the seal portion while being relaxed. 
         [0057]    Next, a second embodiment of the present invention will be described. The second embodiment employs, instead of the embossing roll having protrusions spaced apart from one another, an embossing roll including depressions having a length of 1 mm to 25 mm and a width of 0.5 mm to 15 mm and a latticed protrusion (ridges) having a width of 0.5 mm to 5 mm. As illustrated in  FIG. 6 , the latticed protrusion  63  includes a large number of ridges  61 ,  61 , . . . , which are arranged in the form of parallel crosses, with each space  62  surrounded by the ridges  61  being a depression. W 3  denotes the width of each ridge, which is 0.5 mm to 5 mm. An excessively large width of the ridges may deteriorate the feel/touch of the manufactured article, while the ridges having a width smaller than 0.5 mm may possibly cut off the sheet. D 3  is the length of each depression, which is preferably 5 mm to 25 mm, and more preferably 5 mm to 10 mm. M 3  is the width of each depression, which is preferably 5 mm to 25 mm, and more preferably 5 mm to 10 mm. 
         [0058]    While  FIG. 6  shows a slanted lattice pattern, the pattern may alternatively be any other polygonal lattice pattern such as a square lattice pattern or a rectangular lattice pattern. In this embodiment, the seal portions are in a lattice pattern, whereby it is possible to reliably cut off the elastic member. Moreover, since the latticed protrusion made up of narrow ridges extends across a sufficiently large area in a meshed pattern, the elastic member can be cut off by any of the seal portions. Where the sealing is provided by using a single line blade, all the elastic members need to be cut off by the single line blade, whereby it is necessary to perform strong sealing so that no elastic member is left uncut. As a result, the sheet may possibly be cut off. With the above-described arrangement, the elastic member can be cut off by any of the seal portions. Therefore, the sheet will not be cut off because it is not necessary to perform strong sealing and the contact surface between the sheet and the protrusion is increased. Moreover, such a latticed seal portion gives the wearer a soft feel/touch, and also is aesthetically desirable. Also in the second embodiment, the sheet may include hot melt adhesive portions and non-adhesive portions, or the hot melt adhesive may be continuously applied on the sheet without providing the non-adhesive portions. 
         [0059]    At least one of the embossing roll  50  and the counter roll  60  illustrated in  FIG. 1  may include a heating member. Moreover, other heating members such as a rod-shaped sheathed heater, a high-frequency heating member, a far infrared heater, or an oil heater, may be additionally provided in the vicinity of these rolls. In the arrangement of  FIG. 1 , the positions of the embossing roll  50  and the counter roll  60  may be reversed. 
         [0060]    It is preferred that either the first sheet  10  or the second sheet  30  is heat sealable. Applicable types of sheet include non-woven fabric, a plastic film, knit fabric, woven fabric, paper, etc. Applicable sheet materials include known materials such as a polypropylene, a polyethylene, a polyester, a cellulose, a rayon, etc., which can be used alone or in combination of two or more. Each of the sheets  10  and  30  may be a multi-layer sheet including a number of sheets laminated together. In such a case, a heat sealable sheet should be provided on the uppermost surface of the first sheet  10  or on the lowermost surface of the second sheet  30 . 
         [0061]    The elastic member may be made of a material that can be cut off by heat (e.g., a thermoplastic polyurethane, an elastomer, a rubber, etc.), and may be provided in the form of a ribbon or a string. A film-shaped elastic member (e.g., an elastomer film) can also be used because it can be reliably cut off by seal portions arranged in a staggered pattern or a lattice pattern. It is preferred that the elastic member has a melting point that is lower than that of the heat sealable material of the second sheet so that the second sheet will not be cut off. The melting point of the second sheet may be higher than that of the first sheet. 
         [0062]    While  FIG. 1  illustrates an example where the elastic member is adhered in the widthwise central portion of the sheet, the elastic member may alternatively be adhered near the edge of the sheet. In such a case, the emboss pattern can be changed according to the position of the elastic member. 
         [0063]    According to the present invention, the seal portions can be made non-elastic after the heat seal process not only in the case where an adhesive is applied so as to provide non-adhesive portions and adhesive portions but also in the case where the adhesive application is continuous. Therefore, an elastic sheet having alternating elastic and non-elastic portions can be continuously manufactured.

Technology Category: 4