Sheet Package

Abstract: A sheet package can prevent a sheet (10) from causing damage upon dispensing the sheet through a dispensing openig without widening an opening width of the dispensing opening (4) and providing extra gap within a package container (40). The sheet package includes a sheet stack (1), in which a plurality of folded sheets are stacked, receiced within a package container with a dispensing opening. Each individual sheet is folded into two-ply sheet along a first folding line (11), two sheets of the two-ply sheet are folded along a second folding line (12a,12b) extending in parallel to the first folding line together for forming a folded sheet, a plurality of folded sheets are stacked in such a manner that a portion including the first folding line of a lower folded sheet is disposed within a valley folded portion of an upper folded sheet.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a sheet package housing a sheet stack in which a plurality of sheets are stacked, received within a package container having a dispensing opening. Description of the Related Art Some of sheets for hand cleaning, baby wipes or sheets for cleaning toilet, kitchen and so forth are provided as wet type sheet. Such wet type sheets are sealingly received within a package container, such as a hard packaging vessel and a bag formed of a packaging sheet in order to maintain wet condition. The package container is formed with a dispensing opening so as to permit sequential dispensing of the sheets. On the other hand, this kind of sheets are so combined as to link vertically adjacent sheets with each other, so that next sheet is drawn together with the uppermost sheet to project the upper portion thereof through the dispensing opening when the uppermost sheet is pulled out. Such type of the sheet package is typically called as pop-up type. Prior art of a sheet stack of the wet type sheet as pop-up type will be discussed with reference to Figs. 6 and 7. The sheet stack shown in Fig. 6 is formed by stacking a plurality of folded sheets 80 combined with each other. Each sheet 80 is folded in a folding line 81 to form an upper piece 82 and a lower piece 83. The odd number order sheets 80 and the even number order sheets 80 are combined symmetrically with each other. Between the upper piece 82 and the lower piece 83 of the upper sheet (or the overlying sheet), the upper piece 82 of the lower sheet (or the underlying sheet) is disposed. An overlapping width between the lower piece 83 of the upper sheet and the upper piece 82 of the lower sheet are set in an extent of 30 mm, for example. The lower piece 83 and the upper piece 82 are joined by a water screen. The sheet stack is housed within a package container 100, such as a hard packaging vessel, a packaging bag or the like, provided with a dispensing opening 100a. Pinching the upper piece 82 of the upper sheet with fingers and pulling out the same through the dispensing opening 100a, the lower sheet is drawn at the upper piece by the lower piece of the upper sheet. Then, due to resistance at the edge portion of the dispensing opening 100a, joining between the upper sheet and the lower sheet by the water screen is broken to separate theupper sheet and the lower sheet. As a result, the upper piece 82 of the lower sheet is projected from the dispensing opening 100a to facilitate dispensing of the next sheet. Each sheet 90 in the sheet stack shown in Fig. 7 is folded in such a manner that an upper piece 91 is placed at upper side of an intermediate piece 93 and a lower piece 92 is placed at lower side of the intermediate piece 93. Thus, the sheet 90 is folded into substantially Z-shape. In the sheet stack, the upper piece 91 of the lower sheet is disposed between the intermediate piece 93 and the lower piece 92 of the upper sheet. When the upper piece 91 of the upper sheet is drawn out through the dispensing opening 100a of the package container 100, the upper piece 91 of the lower sheet is trained (or dragged) together with the lower piece 92 of the upper sheet to be drawn out through the dispensing opening 100a to project therefrom. However, in the sheet stacks shown in Figs. 6 and 7, the lower sheet is drawn out to project from the dispensing opening 100a when the upper sheet is dispensed through the dispensing opening 100a. For separating the lower sheet from the upper sheet as trained, a resistance force is exerted on the upper piece 82 projecting through the dispensing opening 100a in case of the sheet stack shown in Fig. 6. On the other hand, the resistance force is exerted on the upper piece 91 projecting through the dispensing opening 100a in case of the sheet stack shown in Fig. 7. Therefore, in the case where strength of each sheet is low in dispensing direction, when the upper piece 82 or 91 projecting from the dispensing opening 100a is drawn out with pinching by fingers, the sheet may be broken at the mid-way of dispensing due to sliding resistance between the edge portion of the dispensing opening 100a and the sheet, or the sheet may be damaged to be locally become thin due to separation between the fibers. Particularly, when the sheets in the package container 100 is in wet condition, strength of each sheet becomes low. Furthermore, when the sheet 80 or 90 is water-decomposable sheet to be dispersed in large amount of water as disposed into flush toilet after use, the breaking strength in dispensing direction is typically less than or equal to 4.9N per 25 mm width in wet condition. Therefore, the water-decomposable sheet can be damaged by resistance as being dispensed through the dispensing opening 100a. For preventing damage to the sheet dispensed as a single sheet as set forth above, an inner width W100 of the dispensing opening 100a is required to be widened to reduce sliding resistance to be exerted on the sheet from the edge portion of the dispensing opening 100a. However, when the inner width W100 of the dispensing opening 100a becomes excessively wide, the sheets within the package container 100 in wet condition can be easily dried. Also, since a cover member closing the dispensing opening 100a becomes excessively large to cause difficulty in certainly adhering the cover member in the circumference of the dispensing opening 100a when the dispensing opening 100a is covered by the cover member. If closure of the dispensing opening 100a by the cover member is incomplete, the sheet can be easily dried. On the other hand, when number of sheets to be received is smaller as compared with a volume of the package container and when a slight gap is formed between the uppermost sheet and the dispensing opening, resistance to be exerted as dispensing uppermost several sheets becomes smaller. However, in this case, excessive size of the package container becomes necessary as compared with the sheet stack. On the other hand, when the package container is formed with a packaging sheet, the package container is formed by wrapping the sheet stack with the package sheet. At this time, it is difficult to continuously and automatically perform operation for packing the sheet stacked with maintaining a gap (space) within the package container. US Patent 5,118,554, upon which the preamble of claim 1 is based, discloses sheet towels for a towel dispenser, where each sheet is formed of two plies by first folding a single ply sheet in half to form a leading edge. The two ply sheets are then interlaced in a conventional manner with the leading edge being first presented to a user so that both plies of a sheet are drawn from the dispenser together. SUMMARY OF THE INVENTION The present invention has been worked out in view of the problems in the prior art as set forth above. It is therefore an object of the present invention to provide a sheet package which can prevent from causing damage to a sheet upon dispensing the sheet through a dispensing opening without widening an opening width of the dispensing opening and providing extra gap within a package container. According to the first aspect of the present invention, there is provided a sheet package including a sheet stack in which a plurality of folded sheets are stacked, received within a package container with a dispensing opening, each individual sheet being folded into a two-ply sheet along a first folding line, two sheets of said two-ply sheet are together folded along a second folding line extending parallel to said first folding line to form a folded sheet with a plurality of folded sheets stacked in such a manner that a portion including said first folding line of a lower folded sheet is disposed within a valley folded portion of an upper folded sheet, said folded sheets in said sheet stack include first folded sheets oriented in one direction and second folded sheets oriented in the other direction, said first and second folded sheets being stacked alternately in such a manner that said portion including said first folding line of a lower one of said first or second folded sheets is disposed within said valley folded portion of the other upper one of said first or second folded sheet, wherein said portion including said first folding line of a lower one of said first or second folded sheet and said portion including said first folding line of the other upper one of said first or second folded sheet do not overlap with each other on a centre line (0-0) extending in the sheet stacking direction. The sheet stack may be formed by placing the first folding line of each folded sheet within a width range of the dispensing opening. The sheet may be a water decomposable sheet disposed within the package container in wet condition, the two-ply sheet may have a breaking strength less than or equal to 9.8N per 25 mm width in wet condition in a direction perpendicular to the first folding line. The two-ply sheet may be formed by folding an essentially rectangular flat one-ply sheet at the first folding line inclined to one of opposite shorter edges so that shorter edges of the two-ply sheet as folded along the first folding line are offset from each other, and two sheet fractions continuous across the first folding line for forming the two-ply sheet have mutually different length in a direction perpendicular to a direction along which the first folding line extends, one of the sheet fraction having shorter length of the first and second folded sheets do not overlap with each other as stacked. The two-ply sheets may be interfolded with each other in such a manner that when an uppermost sheet is withdrawn through the dispensing opening, a succeeding sheet follows and is separated at the dispensing opening to be retained projecting a portion including the first folding line from the dispensing opening so that portion of the sheet in two-ply structure is constantly gripped as withdrawn from the package container. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood more fully from the detailed descriptive given hereinafter and from the accompanying drawings of the preferred embodiment of the present invention, which, however, should not be taken to be limitative to the invention, but are for explanation and understanding only. In the drawings: Figure 1 is a section of the sheet package according to the present invention; Figures 2A and 2B are perspective views showing manner of folding of an individual sheet forming the sheet stack; Figure 3 is a section showing a more preferred modification of the sheet package according to the present invention; Figure 4 is a section for explaining one conventional sheet package; and Figure 5 is a section for explaining another conventional sheet package. DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will be discussed hereinafter in detail in terms of the preferred embodiment of the present invention with reference to the accompanying drawings. Figure 1 is a section of a sheet package according to the present invention, and Figures 2A and 2B are perspective views showing manner of folding of an individual sheet forming the sheet stack. The package container 40 of Figure 1 may be a hard packaging vessel formed of a plastic material or a packaging bag formed of a laminated material of a soft packaging sheet, such as a resin film and an aluminium foil and so forth. On the other hand, it is also possible that the packaging bag containing the sheet stack is used as received within the hard packaging vessel. In an upper portion (upper surface) of the package container 40, a dispensing opening 41 is formed. The sheet package shown in Figure 1 is formed by disposing a sheet stack within package container 40. In the shown embodiment, each individual sheet 20 forming the sheet stack 2 in developed condition has rectangular shape having longer edges 20a and shorter edges 20b and 20c, as shown in Figure 2A. As shown in Figure 2A, the sheet 20 is folded into a two-ply sheet 20A along a first folding line 21 parallel to the shorter edges 20b and 20c. The first folding line 21 is formed at a position inclined toward one shorter edge 20c from a centre position of the length W0 of the longer edge 20a. Therefore, as shown in Figure 2B, one shorter edge 20c is located at closer position to the first folding line 21 than the other shorter edge 20b. Thus, the shorter edges 20b and 20c are offset with each other. As shown in Figure 2B, the two-ply sheet 20A is further folded along a second folding line 22 extending in parallel to the first folding line 21. The second folding line 22 is set at a position having two-ply structure. Accordingly, the second folding line 22 is consisted of an inner folding line 22a on one sheet fraction located at inner side and an outer folding line 22b on the other sheet fraction located at outer side, continuous with the one sheet fraction across the first folding line 21 and thus forming the two-ply sheet 20A together with one sheet fraction. Two sheet fractions of the two-ply sheet 20A are folded together at their respective inner and outer folding lines 22a and 22b to form a four-ply V-folded sheet 20B. In the sheet stack 2 shown in Figure 1, first four-ply V-folded sheets 20B and second four-ply V-folded sheets 20B respectively folded in mutually opposite directions. In the sheet stack 2, the first and second four-ply V-folded sheets 20B are alternately stacked in laterally symmetrical fashion with placing the sheet fraction having the shorter edges 20b inner side. In case of the sheet stack 2 shown in Figure 1, the four-ply V-folded sheet 20B as folded along the second folding line 22 defines a valley folded portion between the lower surface of an upper piece 20B1 and the upper surface of the lower piece 20B2 as folded along the inner folding line 22a. In the valley folded portion of one four-ply folded sheet 20B, the upper piece 20B1 of the next lower four-ply V-folded sheet 20B with the folded edge along the first folding line 21 is placed. Thus, the upper piece 20B1 of the next lower four-ply V-folded sheet 20B is disposed between the upper and lower pieces 20B1 and 20B2 of one four-ply V-folded sheet 20B. With respect to a centre line O - O extending in sheet stacking direction at a position half of the width W20, the folded portions along the first folding lines 21 in the first and second four-ply V-folded sheets 20B are located close to the centre line O - O so that the folded portion along the first folding line 21, namely a tip end of the upper piece 20B1 of the four-ply V-folded sheet always falls within an area of the dispensing opening 41 of the width Wa when the sheet is dispensed through the dispensing opening 41 in order. In the sheet package shown in Figure 1, since the tip end of the upper piece 20B1 of the four-ply V-folded sheet 208 is exposed through the dispensing opening 41, the two-ply sheet is gripped by finger at the tip end along the first folding line 11 to be pulled up for dispensing. When each sheet is in a condition impregnated by water or chemical solution (ie, wet condition), the lower piece 20B2 of the four-ply V-folded sheet to be withdrawn and the upper piece 20B1 of the next lower four-ply V-folded sheet are tightly fitted by the water screen. Therefore, when the uppermost four-ply V-folded sheet is withdrawn from the dispensing opening 41, the next lower four-ply V-folded sheet is pulled up together with the uppermost four-ply V-folded sheet to project from the dispensing opening 41. Then, by exerting a resistance force on the next lower four-ply V-folded sheet being pulled out from the edge portion of the dispensing opening 41, the uppermost sheet being withdrawn or dispensed and the next lower sheet joined at the mating portions of the width W3 are separated. Then, the upper piece 10B1 of the next lower sheet is held in slightly projecting condition from the dispensing opening 41. Therefore, at the next time, the sheet projecting from the dispensing opening 41 can be gripped and withdrawn through the dispensing opening 41. In the condition retained in the dispensing opening 41 after dispensing the preceding sheet, the tip end as folded along the first folding line 11 is orientated upwardly. On the other hand, since the two-ply sheets are folded together at the second folding line 22 (at the inner folding line 22a and the outer folding line 22b), the entire upper piece 20B1 has two-ply structure. When the next lower sheet is pulled following the uppermost sheet to project from the dispensing opening 41, the upper piece 20B1 primarily receives the resistance force from the edge portion of the dispensing opening 41. Since the upper piece 20B1 is two-ply sheet structure, the strength of the upper piece 20B1 is sufficiently high to prevent from causing rupture or damage due to resistance. Therefore, even if the sheet per se has low wet strength, the sheet may hardly cause rupture or damage, such as expansion of gap between the fibres or so forth, due to sliding resistance of the dispensing opening 41. For example, the sheet 20 may be water decomposable sheet having low wet strength. The water decomposable sheet may be decomposed by dispersing fibres with a large amount of water as disposed into a flush toilet. For example, the water decomposable sheet may be a paper or non-woven fabric made of fibres such as rayon or pulp and containing water decomposable or water-swelling binder such as CMC (carboxymethyl cellulose); or non-woven fabric fabricated by entangling fibres such as rayon or the like of fibre length shorter than or equal to 10 mm or shorter than or equal to 7 mm by water-jetting treatment, so that the entangled short fibres having fibre length shorter than or equal to 10 mm are separated and dispersed as applied a large amount of water. In the alternative, the water decomposable sheet may be a paper or non-woven fabric containing fibrillated rayon in rayon or pulp, in which the fibrillated rayon acts as binder. Typical water-decomposable sheet in wet condition has a breaking strength less than or equal to 4.9N per 25 mm width in a direction of withdrawing the sheet through the dispensing opening 41 (i.e., the dispensing direction), as one-ply sheet. Even with such sheet having low breaking strength, the sheet package of the present invention can be embodied with avoiding the problem to be damaged by the resistance to be exerted by the edge portion of the dispensing opening 41. It should be noted that the breaking strength herein referred to is expressed by a tension load upon occurrence of rupture on a test sample of 25 mm width and 150 mm length as subject to tensile test by impregnating with moisture of 2.5 times of a weight of the sheet (i.e., the test sample), chucking between chucks of Tensilon Tester at an initial distance of 100 mm, and applying a tension between the chucks at a speed of 100 mm/min. In the sheet stack 2,the first folding line 21 (21A) of the first four-ply V-folded sheet 20B and the first folding line 21 (21B0 of the second four-ply V-folded sheet 20B are placed on the centre line O - O extending in sheet stacking direction without overlapping with each other. While the shown embodiment is illustrated in a form where the first folding line 21 (21A) of the first four-ply V-folded sheet 20B and the first folding line 21 (21B0 of the second four-ply V-folded sheet 20B are placed on the centre line O - O, it is also possible to combine the first and second four-ply V-folded sheets 20B with placing the first folding line 21 (21A0 on left side of the centre line O - O in Figure 1, and placing the first folding line 21 (21B) on right side of the centre line O - O in Figure 1. Therefore, the upper pieces 20B1 of the first and second four-ply V-folded sheets 20B in two-ply structure do not overlap as stacking alternately the first and second four-ply V-folded sheets 20B for avoiding increasing of thickness due to overlapping of the upper pieces 20B1. This prevents thickening of the sheet stack 2 at the centre portion. On the other hand, since the first folding lines 21 (21A, 21B) of respective sheets are located substantially centre of the dispensing opening 41 having the width Wa, even if the upper piece 20B1 of the next lower sheet fails to follow the uppermost sheet as disposed, the upper edge of the upper piece 20B1 along the first folding line 21 placed inside of the package container 40 can be easily withdrawn through the dispensing opening 41. Even in the shown embodiment, when resistance is exerted on the upper piece 20B1 of the two-ply structure from the edge portion of the dispensing opening 41 upon dispensing the sheet, the sheet is hardly damage even though one-ply sheet has low wet strength. In the embodiment shown in Figures 1, 2A and 2B, a length W0 of the longer edge 20a of the sheet 20 is 190 mm in developed condition, a length W4 of the upper piece 20B1 between the first folding line 21 and the second folding line 22 is 37.5 mm, a length W5 from the second folding line 22 to one shorter edge 20b is 67.5 mm, and a length W6 from the second folding line 22 to the other shorter edge 20c is 47.5 mm, for example. In this case, assuming that the overlapping width W3 of the upper piece 20B1 and the lower piece 20B2 of adjacent first and second four-ply V-shaped sheets is 30 mm, the width W20 of the sheet stack 2 becomes 75 mm. Figure 3 is a section showing a more preferred modification of the sheet package according to the invention shown in Figure 1. A sheet stack 3 shown in Figure 3 is basically the same as the embodiment shown in Figure 1, 2A and 2B in folding method of respective sheets and the manner of combination of the folded sheets. In Figure 3, the first and second four-ply V-folded sheets 20B are combined with placing the first folding line 21 (21A) on the left side of the centre line O - O in Figure 3, and placing the first folding line 21 (2B) on right side of the centre line O - O in Figure 3. Thus, the first folding line 21A of the first four-ply V-folded sheet 20B and the first folding line 21B of the first four-ply V-folded sheet 20B are located in the vicinity of the centre line O - O without overlapping. In the embodiment shown in Figure 3, a length W7 between the shorter edge 20C and the second folding line 22 is substantially equal to the length of the upper piece 20B1. The first and second four-ply V-folded sheets 20B as alternately stacked in such a manner that the shorter edges 20C of the first four-ply V-folded sheets 20B and the shorter edges 20C of the second four-ply V-folded sheets 20B do not overlap at a position in the vicinity of the centre line O - O. Therefore, when number of the first four-ply V-folded sheet 20B and number of the second four-ply V-folded sheet 20B are equal to each other, total numbers of sheets on left side and right side of the centre line O - O become equal to each other. For example, as shown in Figure 3, assuming that three first four-ply V-folded sheets and three second four-ply V-folded sheets are combined, number of sheets on left side and right side becomes fifteen on both sides. Therefore, the sheet stack 3 becomes flat without causing local bulging. In the sheet stack 3 shown in Figure 3, a length W0 of the longer edge 20a of the sheet 20 is 190 mm in developed condition, a length W7 of the upper piece 20B1 between the first folding line 21 and the second folding line 22, that is, a length W7 between the second folding line 22 and one shorter edge 20c is 40 mm, and a length W8 between the second folding line 22 and the other shorter edge 20b is 70 mm. In this case, assuming that the overlapping width W3 of the upper piece 20B1 and the lower piece 20B2 of adjacent first and second four-ply V-folded sheets is 30 mm, the width W30 of the sheet stack 2 becomes 80 mm. With the present invention, the sheet package according to the present invention hardly causes breakage on the sheet with minimizing damage upon dispensing or withdrawing the sheet through the dispensing opening. Therefore, when the water decomposable sheet is package in wet condition or in other occasion, even if the strength of the individual sheet is low, damage of the sheet is hardly caused. Although the present invention has been illustrated and described with respect to exemplary embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without departing from the spirit and scope of the present invention. Therefore, the present invention should not be understood as limited to the specific embodiment set out above but to include all possible embodiments which can be embodied within a scope encompassed and equivalent thereof with respect to the feature set out in the appended claims. It should be noted that when the sheet stack is formed by folding the sheet such as wet tissue by a machine, it is inherent to cause tolerance in folding dimension in each individual sheet. Therefore, there is a possibility that the sheet stacks shown in Figures 1 and 3 may have some sheets in which the first folding lines 21 or the shorter edges 20c extend across the centre line O - O. The requirement of the present invention should be satisfied as long as at least some of the sheets are combined or stacked so that the first folding lines 21 or the shorter edges 20c do not overlap on the centre line O - O. On the other hand, the present invention is not limited to the sheet package, in which the sheets are packaged in wet condition, but can be the sheet package, in which the sheets are packaged in dry condition. Even in the latter case, by constructing to dispense or withdraw the sheet in two-ply structure, damaging of the sheet can be successfully prevented.

Claims: A sheet package including a sheet stack (2) in which a plurality of folded sheets are stacked, received within a package container (40) with a dispensing opening (41), each individual sheet (20) being folded into a two-ply sheet (20A) along a first folding line (22), two sheets of said two-ply sheet are together folded along a second folding line (22) extending parallel to said first folding line to form a folded sheet (20B) with a plurality of folded sheets stacked in such a manner that a portion including said first folding line (22) of a lower folded sheet is disposed within a valley folded portion of an upper folded sheet, said folded sheets (20B) in said sheet stack include first folded sheets (20B) oriented in one direction and second folded sheets (20B) oriented in the other direction, said first and second folded sheets being stacked alternately in such a manner that said portion (20B1) including said first folding line (21) of a lower one of said first or second folded sheets is disposed within said valley folded portion of the other upper one of said first or second folded sheet (20B), wherein said portion (20B1) including said first folding line (21) of a lower one of said first or second folded sheet and said portion (20B1) including said first folding line (22) of the other upper one of said first or second folded sheet do not overlap with each other on a centre line (0-0) extending in the sheet stacking direction. A sheet package as claimed in Claim 1, wherein said two-ply sheet (20A) is formed by folding an essentially rectangular flat one-ply sheet (20) at said first folding line (21) nearer to one of opposite shorter edges (20b, 20c) so that shorter edges (20b, 20c) of said two-ply sheet (20B) as folded along said first folding line (21) are offset from each other, and two sheet fractions continuous across said first folding line (22) for forming said two-ply sheet have mutually different lengths in a direction perpendicular to a direction along which said first folding line (22) extends, wherein the sheet fractions of said first and second folded sheets (20B2) having shorter length do not overlap each other when stacked. A sheet package as claimed in Claim 1, wherein said sheet stack (2) is formed placing said first folding line (22) of each folded sheet within a width range (Wa) of said dispensing opening (41). A sheet package as set forth in claim 1, wherein said sheet (20A) is a water decomposable sheet disposed within said package container (40) in wet condition, said two-ply sheet (20A) has a breaking strength less than or equal to 9.8N per 25 mm width in wet condition in a direction perpendicular to said first folding line (22). A sheet package as claimed in any preceding claim, wherein said two-ply sheets are interfolded with each other in such a manner that when an uppermost sheet (20B) is withdrawn through said dispensing opening (41), a succeeding sheet (20B) follows and is separated at said dispensing opening (41) to be retained projecting a portion including said first folding line from said dispensing opening so that a portion of the sheet (20A) in two-ply structure may be constantly gripped as the sheet is withdrawn from said package container.

Inventors: IIDA YUKIKO, IIDA, YUKIKO, Iida, Yukiko, c/o Technical Center
Applicants: UNI CHARM CORP, UNI-CHARM CORPORATION
Application year: 2001
Main classification: B65D83
IPC codes: A47K10, B65D83, A47K7, B65H45