Method for manufacturing wearable article components

Abstract: A manufacturing method of structural parts for wearing products is described which allows partial webs having one concavoconvex edge to be attached to other parts of the product in a high speed process of manufacturing these vearing products. A concavoconvex cutting line (33) is applied in the longitudinal direction of a first web (30) to form first and second partial webs (30a,30b,130a,130b). The first partial web (30a,130a) is offset with respect to the second partial web (30b,130b) in the longitudinal direction thereof by a prescribed interval, so that the concave edges and the convex edges (33a,33b) of the first and the second partial webs (30a,30b,130a,130b) are positioned opposite and aligned to each other respectively. Thereafter the wearing products are manufactured with these partial webs arranged on the outsides thereof.

Description: Detailed explanation of the invention Industrial application field This invention concerns a manufacturing method of the structural parts for wearing products. More specifically, it concerns a manufacturing method of the structural parts of disposable diapers, baby training pants, or other wearing products. Conventional techniques In the conventional manufacturing method of disposable wearing products, in order to cut the manufacturing cost by reducing waste in the materials, a continuous web is cut along the longitudinal central line to form symmetric concavoconvex edge portions. Then, the partial webs are cut at the prescribed length to form the structural parts, such as disclosed in JP-A-62231659 and US-A-4 760 764 (corresponding to JP-A-62250202). In JP-A-62231659, it is indicated that the said partial webs are assembled as the tape fastener of the disposable diaper. However, there is no specific description of this method. In US-A-4 760 764, it is pointed out that the said partial webs are used to form the die-shaped [sic] absorptive body which is used to assemble the disposable diaper. In this scheme, one of the pair of partial webs having concavoconvex edge portions makes a rotation around an oblique roll so that it is offset from the other web; in this way, with the concavoconvex edge portions of the webs located on the outsides and symmetric to each other, they are laminated with each other, followed by cutting at prescribed positions in the transverse direction to form the die-shaped absorptive body. WO 83/03 051 discloses a method of longitudinal offsetting of partial web parts after concavoconvex axial cutting. After cutting, the parts are bonded directly to the end product. Problems to be solved by the invention However, in the scheme disclosed in US-A-4 760 764, as one of the partial webs is made to rotate 1 cycle on an oblique roll so that it is offset with respect to the other partial web, the interval alignment is difficult because the said partial web may easily slide in the axial direction on the roll. Besides, when twisting takes place for one partial web, the other partial web may be entangled with the first partial web. Hence, it is still a topic to be solved for incorporating these webs at a high speed with the other structural parts. The purpose of this invention is to provide a manufacturing method of the structural parts of the wearing product characterized by the following features: for a pair of partial webs, one web is offset with respect to the other web without twisting or entangling with each other; the concave edge portions and the convex edge portions of these webs are made opposite and aligned to each other, respectively; with these aligned concavoconvex portions of the webs arranged on the outsides, the wearing product is manufactured. Means to solve the problem In order to realize the aforementioned purpose, in the method of this invention, a concavoconvex cutting line is applied repetitively in a periodical way in the longitudinal direction of a continuous first web to form the first and second partial webs; the said first partial web is offset with respect to the said second partial web in the longitudinal direction by a prescribed interval, so that the concave edges and the convex edges of the first and second partial webs are positioned opposite and aligned to each other, respectively. Then, a continuous second web is used to connect the outside edges opposite to the said aligned concave and convex edge portions of the first and second partial webs; as the second web is bonded with the outside edges of the partial webs, a composite web is formed; the first and second partial webs of the composite web are spread-to the outer sides. When the said first and second partial webs are bonded with the said second web, a fold-back portion can be formed at each outside edge portion of the second web and the formed fold-back portions are bonded with the outside edges of the first and second partial webs; it is also possible to form fold-back portions at the outer edge portions of the first and second partial webs and to bond these fold-back portions with the outside edge portions of the second web. It is preferred that the said first partial web be offset by a prescribed interval in the longitudinal direction with respect to the said second partial web to ensure alignment between the opposite concave edge portions and between the opposite concave edge portions of the first and second partial webs by arranging a roller with a prescribed diameter at a position in the direction perpendicular to the transfer plane of the second partial web with a prescribed vertical difference and at a right angle to the transfer direction of the first and second partial web and making the first partial web go through this roller. Effects of the invention According to the method of this invention, the first and second [partial] webs formed by dividing are positioned properly to ensure that the opposite concave edge portions as well as the convex edge portions positioned at the central portions of the said partial webs are aligned with each other, respectively; the outer edge portions of a second web are bonded with the outer edge portions of the aligned first and second partial webs to form a composite web; by spreading the first and second partial webs of the composite web outwards, the concave and convex edge portions are positioned on the outer sides. This scheme for positioning the opposite aligned concave and convex edge portions on the outsides is very simple. In addition, fold-back portions are formed on the outer edges of the second web. The fold-back portions are bonded with the outer edges of the first and second partial webs. It is also possible to form the fold-back portions at the outer edges of the first and second partial webs, and to bond these fold-back portions to the second web. In this way, the said spreading operation can be carried out easily, and the finish of the said compound web is excellent. In addition, a roller with a prescribed diameter is set above the transfer plane of the second partial web with a certain height in the vertical direction and at a right angle to the transfer direction of the first and second partial web. By making the first partial web go around this roller, the first partial web is offset with respect to the second partial web to ensure the alignment between the opposite concave and convex edge portions. In this way, without twisting the first web and without the need to cross the first and second webs, these webs can be assembled with other structural parts at a high speed in a stable way. The method of this invention can be used for manufacturing various structural parts of wearing products, such as top sheets, back sheets, mat-shaped cores, tape fasteners, etc. Brief explanation of the figures In the following, the application examples of the method of this invention will be explained with reference to figures. Figure 1 is a schematic side view of the apparatus for implementing the method of this invention. Figure 2 is a schematic side view of another apparatus for implementing the method of this invention. Figure 3 is an oblique view of a portion of the apparatus shown in Figure 2. Figure 4 is a plane view showing the state of aligned opposite concave and convex edges of the first and second partial webs formed by cutting along the concavoconvex cutting line running along the longitudinal central line of the first web in a symmetric way. Figure 5 is a cross-sectional view cut along the V-V line in Figure 4. Figure 6 is a plane view illustrating the state of the composite web in Figure 4 with portions of it spread outwards. Figure 7 is a cross-sectional view cut along VII-VII line in Figure 6. Figures 8A, 8B, 8C, and 8D are also cross-sectional views similar to Figure 5 illustrating other examples of composite webs. Figures 1-3 schematically illustrate apparatus 10 for implementing the method of this invention. In apparatus 10 shown in Figure 1, there are the following parts for processing continuous first web 30: roll cutter 11, guide rolls 12, 13, 14, bearing roll 15, and pressing roll 16. In apparatus 10 shown in Figure 2, the following parts are used to process continuous first web 30: roll cutter 11, guide rolls 12, 13, and guide/pressing roll 17. In apparatus 10 shown in Figure 1, guide roll 12 is arranged at a certain distance above guide rolls 13, 14 which are arranged opposite to each other at a certain distance. On the other hand, in apparatus 10 shown in Figure 2, guide roll 12 is arranged in contact with or near guide roll 13 and pressing roll 17 which are located opposite to each other at a certain distance. For apparatus 10 shown in Figure 1 and that shown in Figure 2, the processing operation schemes of the continuous first web 30 are substantially the same. In order to process continuous first web 30 and continuous second web 40, in addition to said bearing roll 15 and said pressing rolls 16 and 17, apparatus 10 also contains a porous belt conveyor 18, a suction unit 19, a bending guider 20, and a coating unit 21. Figure 3 illustrates a portion of apparatus 10 shown in Figure 2. As shown in Figure 4, continuous first web 30 has substantially parallel side edges 31a, 31b; with respect to longitudinal central line 32 cutting line 33 for forming concavo-convex portions is drawn repetitively in a periodical way along the longitudinal direction, so that the first web is cut by said roll cutter 11 to form first division web 30a and [second partial web] 30b having concave edge portions 33a and convex edge portions 33b. As shown in Figure 3 (also see Figures 1 and 2), first partial web 30a is made to pass above guide roll 12 and below guide roll 13 and pressing roll 17. In this way, it is separated from second partial web 30b. At the same time, as it is transferred to bonding station 22 containing bearing roll 15 and pressing roll 16, it is offset in the longitudinal direction by an interval of (1/2)n (where n is an odd number) with respect to second partial web 30b. In this way, concave edge portions 33a as well as convex edge portions 33b of the first and second partial webs 30a, 30b are made opposite and aligned with each other, respectively. In this case, opposite convex edge portions 33b are laminated. In this way, the interval of offset of the first partial web 30a with respect to second partial web 30b in the longitudinal direction can be determined by the diameter of guide roll 12 and the height of guide roll 12 above the transfer plane of second partial web 30b. In the application example, it is preferred that guide roll 12 be rotated. However, it is also possible to arrange guide roll 12 separately without coupling to other rolls by contact between peripheries. In this case, the guide roll may not be rotatable. On the other hand, in folding guider 20, second web 40 has its two sides folded back to the upper surface. After adhesive 42 is coated on fold-back portions 41 by coating unit 21, it is located below said aligned first and second partial webs 30a, 30b; these webs are made to pass between bearing roll 15 and pressing roll 16, 17 together. After this passage, as shown in Figure 5, outside edges 31a, 31b of first and second partial webs 30a, 30b are bonded with fold-back portions 41 of second web 40 by adhesive 42. In this way, a continuous composite web 50 is formed from first and second partial webs 30a, 30b and second web 40. As composite web 50 is transferred to the next stage for processing on belt conveyor 18, first and second partial webs 30a, 30b are spread outwards by a spreading unit (not shown in the figure) arranged on belt conveyor 18 near the downstream side of bonding station 22, as shown in Figures 6 and 7. The composite web 50 that can be manufactured using this scheme can be used as the structural part of wearing products, such as top sheet, back sheet, mat-like core, etc., of disposable diapers. It is well-known that the top sheet is made of nonwoven fabric, porous plastic film, or other thin soft and liquid permeable materials; the back sheet is made of plastic film, laminate of plastic film and nonwoven fabric, or other thin soft and liquid barrier materials; and the mat-like core is made of fluffy pulp, mixture of pulp and high-absorptivity polymer powder, or other relatively thick elastic and liquid absorptive materials. When composite web 50 is used as these structural parts, the first and second partial webs 30a, 30b and second web 40 may be made of materials having different properties. Figures. 8A-8D illustrate some variation examples of the composite web before spreading, manufactured either by the said apparatus 10 in its original form or by an apparatus with positions changed partially from that of apparatus 10. In these figures, as the parts and portions indicated by the same symbols as in said composite web 50 are identical or similar to those of the said composite web, only a minimum explanation for composite webs 50a, 50b, 50c, 50d will be presented. Their manufacturing methods are essentially identical to the manufacturing method of said composite web 50. For composite web 50a shown in Figure 8A, compared with first and second partial webs 30a and 30b, second web 40 and fold-back portions 41 are formed wider. For composite web 50b shown in Figure 8B, compared with second web 40, first and second partial webs 30a, 30b are formed wider, and the two side portions of these partial webs are folded back to the lower surface and bonded-with second web 40. For composite web 50c shown in Figure 8C, relatively thick first and second webs 30a, 30b are connected to relatively thick second web 40 via folded ribbon sheets 43 made of a thin nonwoven fabric which are bonded with them. For composite web 50d shown in Figure 8D, first and second partial webs 30a, 30b are located below second web 40. The composite webs 50a, 50b, and 50d shown in Figures 8A, 8B, and 8D are suitable for applications as the top sheet and/or back sheet of a disposable diaper. The composite web 50c shown in Figure 8C is suitable for application as the mat-like core of a disposable diaper which has two side portions which are difficult to fold back. When continuous composite webs 50 manufactured in the aforementioned scheme are used as, say, the top sheet and back sheet of the disposable diaper (in this case, although not shown in the figures, apparatus 10 has a structure enabling manufacture of continuous composite webs 50 as two rows with one above the other), mat-like cores formed separately are arranged between these sheets intermittently in sequence in the longitudinal direction; the peripheral portions of these sheets are bonded to form diaper laminates in a continuous way. Then, at prescribed positions of the laminate without core inserted, such as the positions indicated by the dash-dot lines in Figure 6, the laminate is cut in the transverse direction to form individual diapers. For the top sheet and back sheet, it is also possible to use the following scheme: only one web is manufactured as a composite web 50, while for the other web, after the said laminate is formed, portions on its outer side are cut off in alignment with the concave edge portions of the first web. In addition, when composite web 50 is the core, composite web 50 can be cut beforehand at said positions 44 to form individual pieces, which are inserted between the top sheet and back sheet intermittently in the longitudinal direction to form the said laminate, which is then cut as mentioned above. In this manufacturing example, the overall configuration of the manufacturing system of diapers is able to form the top sheet and/or back sheet in the form of composite web 50, as apparatus 10 can be incorporated into the said system.

Claims: Manufacturing method of structural parts for wearing products in which a concavoconvex cutting line (33) is applied repetitively in a periodical way in the longitudinal direction of a continuous first web (30) to form the first and second partial webs (30a,30b), the first partial web (30a) is offset with respect to said second partial web (30b) in the longitudinal direction by a prescribed interval, so that the concave edges (33a) and the convex edges (33b) of the first and second partial webs (30a,30b) are positioned opposite and aligned to each other, respectively characterized in that a contiuous second web (40) is used to connect the outside edges (31a,31b) opposite to said aligned concave and convex portions (33a,33b) of the first and second partial webs (30a,30b), that the second web (40) is bonded with outside edges of the partial webs (30a,30b) in order to form a composite web (50,50a,50b,50c,50d), that the first and second partial webs (30a,30b) of the composite web (50,50a,50b,50c,50d) are spread to the outer sides. Manufacturing method as claimed in claim 1, characterized in that a fold-back portion (41) is formed at each outer side edge portion of said second web (40), the fold-back portions (41) are bonded with the outside edges (31a,31b) of said first and second partial webs (30a,30b). Manufacturing method as claimed in claim 1, characterized in that said fold-back portions are formed on the outside edge portions of the first and second partial webs (30a,30b) and the fold-back portions are bonded with the outside edge portions of said second web (40). Manufacturing method as claimed in one of claims 1 to 3, characterized in that a roller (12) with a prescribed diameter is located at a position perpendicular to the transfer plane of said second web (40) with a prescribed vertical difference and at a right angle with a transfer direction of said first and second partial webs (30a,30b), by making the first partial web (30a) pass above the roller (12) the first partial web (30a) is offset appropriately with respect to said second partial web (30b) to ensure the opposite matching positioning of the two partial webs (30a,30b).

Inventors: HOSAKAWA MASASHI, NAKANO SHOJI, OCHI MITSUZO, HOSAKAWA, MASASHI, NAKANO, SHOJI, OCHI, MITSUZO
Applicants: UNI CHARM CORP, UNI-CHARM CORPORATION
Application year: 1990
Main classification: A61F13
IPC codes: A61F5, D06H7, B31D1, A61F13, D06H5