阅读说明：本技术 缝制且穿孔的吸收片材叠堆 (Sewn and perforated absorbent sheet stack ) 是由 J·A·帕维莱特克 C·P·奥尔森 于 2017-05-24 设计创作，主要内容包括：本发明提供了一种叠堆,所述叠堆包括以面对的方式叠堆的多个吸收片材。所述叠堆沿其顶部边缘被至少一行线迹结合,所述至少一行线迹包括多个间隔开的线迹孔眼和设置在所述多个间隔开的线迹孔眼中的线。单独的片材还包括一行穿孔,所述一行穿孔包括多个间隔开的穿孔孔眼。所述一行线迹和所述一行穿孔使得在所述多个线迹孔眼和穿孔孔眼中的至少大部分之间大体上存在一对一的数值对应。(The present invention provides a stack comprising a plurality of absorbent sheets stacked in a facing manner. The stack is joined along its top edge by at least one row of stitches including a plurality of spaced apart stitch apertures and a thread disposed in the plurality of spaced apart stitch apertures. The individual sheets also include a row of perforations that includes a plurality of spaced perforation apertures. The row of stitches and the row of perforations are such that there is substantially a one-to-one numerical correspondence between at least a majority of the plurality of stitch and perforation apertures.)

1. An absorbent sheet stack comprising:

a. a plurality of absorbent sheets having a machine direction and a cross-machine direction and stacked in a facing manner to form a stack of absorbent sheets, the stack having a top edge and a bottom edge;

b. a joining element for joining the sheets together to form a joining element disposed adjacent the top edge of the stack, the joining element including a plurality of spaced apart stitch eyes and a thread disposed between a first stitch eye and a second stitch eye; and

c. a row of perforations comprising a plurality of spaced apart perforation holes, wherein the number of perforation holes corresponds approximately to the number of stitch holes.

2. The stack of absorbent sheets of claim 1, wherein the absorbent sheet has a basis weight of greater than about 10 grams per square meter (gsm), a geometric mean tensile strength (GMT) of from about 500 to about 3,500g/3 ", and a vertical absorbent capacity of greater than about 4.0 g/g.

3. The stack of absorbent sheets of claim 1, wherein the plurality of absorbent sheets comprises half-folded or quarter-folded absorbent sheets.

4. The stack of absorbent sheets of claim 1, wherein at least a portion of the plurality of absorbent sheets further comprises a second row of perforations.

5. The stack of absorbent sheets of claim 1, wherein the stitch aperture has a first shape and the perforation aperture has a second shape, wherein the first shape and the second shape are different.

6. The stack of absorbent sheets of claim 1, wherein the stitch apertures have a circular, semi-circular, or oval shape and the perforation apertures have a rectangular, square, diamond, oval, or linear shape.

7. The stack of absorbent sheets of claim 1, wherein the plurality of spaced apart stitch apertures and the plurality of spaced apart perforation apertures are each substantially linear and arranged parallel to each other.

8. The stack of absorbent sheets of claim 1, further comprising a backing sheet or tape, wherein the taber stiffness of the backing sheet or tape is greater than the taber stiffness of the plurality of absorbent sheets.

9. The stack of absorbent sheets of claim 1, further comprising a backing sheet or tape folded over the top edge of the stack of absorbent sheets to form a portion of the bonding element.

10. The stack of absorbent sheets of claim 9, wherein the plurality of spaced apart stitch apertures are disposed in the backing sheet or strip and the plurality of absorbent sheets.

11. An absorbent sheet stack comprising:

a. a plurality of absorbent sheets stacked in a facing manner to form a stack having a top edge and a bottom edge;

b. a single row of stitches extending parallel to the top edge of the stack, the single row of stitches comprising a plurality of individual stitch apertures and at least one thread disposed between a first stitch aperture and a second stitch aperture of the plurality of individual stitch apertures to form a stitch; and

c. a single row of perforations extending parallel to the top edge of the stack and spaced apart from the single row of stitches, the single row of perforations comprising a plurality of individual perforation apertures, wherein there is a one-to-one numerical correspondence between the plurality of individual perforation apertures and the plurality of individual stitch apertures.

12. The stack of absorbent sheets of claim 11, wherein the absorbent sheet has a basis weight of greater than about 10 grams per square meter (gsm), a geometric mean tensile strength (GMT) of from about 500 to about 3,500g/3 ", and a vertical absorbent capacity of greater than about 4.0 g/g.

13. The stack of absorbent sheets of claim 11, wherein the plurality of absorbent sheets comprises half-folded or quarter-folded absorbent sheets.

14. The stack of absorbent sheets of claim 11, wherein at least a portion of the plurality of absorbent sheets further comprises a second row of perforations.

15. The stack of absorbent sheets of claim 11, wherein the stitch aperture has a first shape and the perforation aperture has a second shape, wherein the first shape and the second shape are different.

16. The stack of absorbent sheets of claim 11, wherein the stitch apertures have a circular, semi-circular, or oval shape and the perforation apertures have a rectangular, square, diamond, oval, or linear shape.

17. The stack of absorbent sheets of claim 11, wherein the plurality of spaced apart stitch perforations and the plurality of spaced apart perforation perforations are each substantially linear and arranged parallel to each other.

18. The stack of absorbent sheets of claim 11, further comprising a backing sheet or tape, wherein the taber stiffness of the backing sheet or tape is greater than the taber stiffness of the plurality of absorbent sheets.

19. The stack of absorbent sheets of claim 11, further comprising a backing sheet or tape folded over the top edge of the stack of absorbent sheets to form a portion of the bonding element.

20. A method of making a stack of sewn and perforated absorbent sheets comprising the steps of:

a. providing a plurality of absorbent sheets;

b. stacking the plurality of absorbent sheets in a manner facing each other;

c. providing a sewing and perforation device comprising a first tine and a second tine; wherein the first tine is adapted to receive a line and the first tine and the second tine are adapted to be displaced in a vertical direction by a drive means;

d. threading the first sharp tooth by using a wire;

e. moving the first tine and the second tine toward and through the stack of sheets, wherein the first tine forms a stitch aperture through which the thread passes and a second aperture forms a perforation aperture; and

f. moving the sewing and perforating apparatus or the stack of sheets in a horizontal direction and repeating step (e).

21. The method of claim 20, further comprising the step of cutting the plurality of sheets to size prior to step (b).

22. The method of claim 20, wherein the plurality of sheets are stacked in alignment with one another such that the machine directions of the sheets are aligned with one another.

23. The method of claim 22, wherein step (f) forms a row of stitch eyes and a row of perforation eyes, the row of stitch eyes and the row of perforation eyes being aligned substantially perpendicular to the machine direction of the sheet.

24. The method of claim 20, further comprising the steps of providing a backing sheet or tape and folding the backing sheet or tape over the first end of the stack.

Background

Consumers desire easy, convenient, and quick access to absorbent sheet products, such as paper towels, toilet tissue, napkins, facial tissues, and the like, for their home or work area. In particular, consumers desire these products to be available in areas where spills or messes occur, which are often found in home areas, such as kitchens or toilets, where such products are traditionally placed. When these areas spill or are messy, consumers desire quick and easy access to the absorbent sheet to quickly clean the mess to avoid damaging the surface in various locations in the home. Accordingly, there is a need for absorbent sheets, and particularly stacks of absorbent sheets, that can be easily placed in various locations in the home and provide a convenient form of distribution to ensure easy, convenient, and quick use of the sheets at and when desired by the consumer.

Not only do consumers demand sheet forms that are easy and convenient to use, they also want forms that are aesthetically pleasing and complement home furnishings. Often to meet the consumer's need for ease and convenience, these sheet products are designed to be placed in a direct view at home, rather than being stored in a cabinet. Therefore, these products must be aesthetically pleasing and capable of being used as home furnishings.

Accordingly, there is a need in the art for an absorbent sheet product that provides consumers with a convenient and easily accessible dispensing means when and where consumers desire such products. Further, there is a need for a dispensing form that can be used as a home decoration and to supplement the home decoration of a consumer.

Disclosure of Invention

The present invention satisfies the need for a convenient and easy to use dispenser for absorbent sheets by consumers. The absorbent sheets are provided in a stack that is sewn along one edge to join the stack, and the individual sheets are perforated to allow easy and convenient removal of the individual sheets. The stack is compact and fashionable, and the sewn combination complements the home decoration of many consumers. Moreover, the stack can be installed in many different locations, thereby allowing consumers to easily access the absorbent sheets at various locations in the home. For example, the stack may be laid flat on a horizontal surface (such as a countertop or table) using conventional and readily available mounting hardware (such as adhesive or mechanical fasteners), or may be mounted to a vertical surface (such as a wall or cabinet).

Accordingly, in one embodiment, the present disclosure provides a stack of absorbent sheet materials comprising: a plurality of absorbent sheets having a machine direction and a cross-machine direction and stacked in a facing manner to form a stack of absorbent sheets, the stack having a top edge and a bottom edge; a bonding element for bonding the sheets together to form a stack disposed adjacent the top edge of the stack, the bonding element comprising a plurality of spaced apart stitch eyes and a thread disposed between a first stitch eye and a second stitch eye; and a row of perforations comprising a plurality of spaced apart perforation apertures, wherein at least a portion of the plurality of stitch apertures are arranged in pairs with a portion of the plurality of perforation apertures.

In certain embodiments, at least about 50%, more preferably at least about 60%, still more preferably at least about 70%, such as from about 50% to about 100%, more preferably from about 70% to about 100%, of the stitch apertures have a corresponding perforation aperture. In this manner, there is a one-to-one numerical correspondence between at least a portion of the plurality of perforation apertures and at least a portion of the plurality of stitch apertures.

In another embodiment, the present disclosure provides a stack of absorbent sheet materials comprising: a plurality of absorbent sheets having a machine direction and a cross-machine direction and stacked in a facing manner to form a stack of absorbent sheets, the stack having a top edge and a bottom edge; a plurality of spaced apart stitch eyes disposed adjacent the top edge of the stack, including a binder of thread disposed between a first stitch eye and a second stitch eye for binding the stack of sheets together; and a row of perforations comprising a plurality of spaced apart perforation apertures, wherein there is a one-to-one numerical correspondence between at least a portion of the plurality of perforation apertures and at least a portion of the plurality of stitch apertures.

The stitching of the stack of absorbent sheets may be performed using one thread, two threads, or three or more threads. Further, the sewing may be performed by any method commonly used for sewing cloth materials, such as single-thread chain stitch, lock stitch, etc.

In one embodiment, the first and second line trace portions belonging to the at least one row are formed by a single line chain stitch of the line.

In another embodiment, the plurality of first and second wire trace portions belonging to the at least one row comprises two continuous wires crossing each other to be bonded to each other so as to be under tension, wherein the first and second wire trace portions are formed by lock-stitch of the two wires.

In other embodiments, the plurality of first and second wire trace portions belonging to the at least one row comprises two continuous wires crossing each other to be bonded to each other so as to be under tension, wherein the first and second wire trace portions are formed by lock-stitch of the two wires. For example, at least one of the first wire trace portions may be adapted to form a separate closed loop with the other wire trace portions, and at least one of the second wire trace portions may also be adapted to form a separate closed loop with the other wire trace portions. The closed loop may be formed by the joining of adjacent wire sections.

In other embodiments, the present disclosure provides an absorbent sheet stack comprising: a plurality of absorbent sheets stacked facing each other to form a stack having a top edge and a bottom edge; a single row of stitches extending parallel to the top edge of the stack, the single row of stitches comprising a plurality of individual stitch apertures and at least one thread disposed between a first thread aperture and a second thread aperture of the plurality of individual stitch apertures to form a stitch; and a single row of perforations extending parallel to the top edge of the stack and spaced apart from the single row of stitches, the single row of perforations comprising a plurality of individual perforation apertures, wherein there is a one-to-one numerical correspondence between the plurality of individual perforation apertures and the plurality of individual stitch apertures.

In other embodiments, the present disclosure provides a method of making a stack of sewn and perforated absorbent sheets, the method comprising the steps of: providing a plurality of absorbent sheets; stacking the plurality of absorbent sheets in a manner facing each other; providing a sewing and perforation device comprising a first tine and a second tine, wherein the first tine is adapted to receive a thread and the first tine and the second tine are adapted to be displaced in a vertical direction by a drive means; threading the first sharp tooth by using a wire; moving the first tine and the second tine toward and through the stack of sheets, wherein the first tine forms a stitch aperture through which the thread passes and a second aperture forms a perforation aperture; and moving the sewing and perforating device or the stack of sheets in a horizontal direction and repeating the previous steps.

Drawings

Fig. 1 is a perspective view of a stack of absorbent sheets according to one embodiment of the present invention;

FIG. 1A is a cross-sectional view through line 1A-1A, showing a line of stitches according to one embodiment of the present invention;

fig. 2 is a perspective view of a stack of absorbent sheets according to another embodiment of the present invention;

FIG. 3 illustrates one embodiment of a row of stitches and a row of perforations for use in the present invention; and is

Fig. 4A-4B illustrate various combinations of stitch and perforation hole shapes for use with the present invention.

Detailed Description

The present invention relates to stacks of absorbent sheets, such as paper towels, toilet tissue, napkins, facial tissue and the like, wherein the stack is thread bonded and individual sheets are perforated to facilitate separation from the stack. The type of material used for the absorbent sheet is understood to include any type of predominantly cellulosic material. However, the term "absorbent sheet" is not limited to paper products such as toilet paper and bath tissue, but may also include absorbent nonwoven materials. These nonwoven materials may comprise synthetic fibers or a mixture of synthetic and cellulosic fibers having properties similar to those of a wet-laid tissue product formed from cellulosic fibers. In certain embodiments, the absorbent material may comprise nonwoven airlaid sheets comprising synthetic fibers, binders, wet strength agents, and the like. The sheets of material are stacked in a facing manner and joined together by stitching and include perforations to facilitate removal of individual sheets from the stack. These and other embodiments will now be discussed in more detail with reference to the accompanying drawings.

Generally, in one embodiment of the invention, the individual sheets in the stack are joined together by sewing the sheets together using a thread. In this way, the stack has sewn regions that define the bonding elements. The bonding elements bond the sheets together and maintain the integrity of the stack. In certain embodiments, the bonding element consists essentially of stitches and is sufficiently strong to bond and hold the sheet material such that the bonding element is substantially free of any adhesive. Thus, in a preferred embodiment, the individual sheets in the stack are stacked in a facing manner without an adhesive disposed therebetween. In other embodiments, the binding element comprises one or more rows of stitches that are sufficiently strong that no other form of mechanical attachment, such as clamps, nails, grommets, or the like, is required.

Although no adhesive or other mechanical attachment means is required, the invention is not so limited. In other embodiments, the bonding element may comprise a hot melt adhesive or a pressure sensitive adhesive in addition to the at least one row of stitches. In other embodiments, adjacent sheets may be bonded to each other by thermal, ultrasonic, or chemical bonding. It should be understood that the aforementioned bonding element is complementary to at least one row of stitches that bonds and holds the individual sheets to form the stack. The supplemental bonding element may be used to bond all of the sheets in the stack, only a portion of the sheets, or in some cases to bond a backsheet or a ribbon to the stack, as discussed in more detail below.

Although a complementary fastener may be employed, in a preferred embodiment, the fastener element consists essentially of one or more rows of stitches. Thus, in a preferred embodiment, the present invention uses at least one row of stitches rather than using adhesive or the like to join the individual sheets together, wherein a single row of stitches may use one thread, two threads, or three or more threads. Various stitches for joining the stack of absorbent sheets will be discussed in more detail below. Stitches may be constructed using well-known sewing techniques, which typically employ needles and threads forming a row of needle holes through which threads or yarns are passed to join a stack of sheet material.

Joining the stack by sewing typically results in the stack having at least one row of stitches comprising a series of successive perforations with lines disposed therebetween. For example, referring to fig. 1, a stack 10 of absorbent sheet material includes a plurality of individual sheets 20 stacked in facing relation to one another and joined by a line of stitches 25. One line of stitches 25 includes a continuous line of spaced stitch eyes 27a, 27b with a line 28 disposed therebetween. The individual sheets also comprise a row of perforations 30 comprising spaced apart individual perforation eyes 31a, 31 b. A line of stitches joins and retains the sheets, while a line of perforations allows the user to separate individual sheets from the stack. Generally, a row of stitches 25 is referred to as a bonding element, and the area of the stack bonded by the row of stitches is referred to herein as a bonding area 21, as shown in fig. 1, adjacent one edge 22 of the sheet material.

The stitching or sewing lines used to join the stack of absorbent sheet material may comprise single or multiple threads. The weight of the thread may be a function of the material properties of the sheets being bonded, such as thickness, fiber composition, tensile strength, and the like. The weight of the thread may be in the range of about 20 to about 120 weight. The thread may comprise about 1 to about 2000 denier, such as about 10 to about 1500 denier, more preferably about 100 to about 1000 denier, still more preferably about 150 to about 500 denier.

The threads may comprise plied or twisted threads (e.g., z-twist or s-twist). The thread material may comprise natural fibers such as cotton, wool, silk or other natural materials, or may comprise synthetic fibers such as polyester, nylon, polypropylene, rayon or other synthetic materials. The thread may comprise a continuous filament. The thread may comprise a monofilament. The thread may comprise a short filament. The wire material may comprise a metal. The wire may comprise a wire, for example, a polymer wire or a composite wire. The wire material is preferably biocompatible and in some aspects absorbable. The wire material may include polydioxanone, polycarbonate, polyurethane, poly (alpha-ester), polyglycolide, polylactide (e.g., poly (L-lactic acid), poly (D-lactic acid) and poly (D, L-lactic acid), poly (4-hydroxybutyric acid), which is a homopolymer of 4-hydroxybutyrate (4HB) belonging to various classes of materials known as Polyhydroxyalkanoate (PHA), and poly (lactide-co-glycolide)), polycaprolactone, polypropylene, polyester, poly (propylene fumarate), polyanhydride, polyacetal, polycarbonate (e.g., poly (trimethylene carbonate)), poly (orthoester), polyphosphazene, polyphosphate, polytetrafluoroethylene, polyethylene terephthalate, or any combination or copolymer thereof. Preferred are polypropylene, polyester and polyethylene, more preferred is monofilament polyethylene.

In those embodiments where more than one wire is used to join the stack, the wires may be the same, or they may be different. For example, if the stack is joined by chain stitch with two threads, the needle thread may comprise a first thread material having a first denier and stretch, and the looper may comprise a second thread material having a second denier and stretch, wherein the denier and stretch of the first thread material and the second thread material are different. Similarly, if a lock stitch is used, the winding line may contain the same thread as the needle thread, or in other cases a different thread.

The number of stitches per unit length in each thread (i.e. the number of surface thread portions of the first and/or second suture portions per unit length) may optionally be selected depending on the kind and material of the absorbent sheets to be stacked and dispensed, the density and thickness of the sheets or the resulting stack, the material and diameter of the suture and the diameter of the suture needle. Similarly, the number of stitches per unit surface area, i.e. the second of the bonding sheets per unit surface area, may be variedThe number of surface thread portions of one suture portion and/or the second suture portion. For example, the number of stitches per unit length may be in the range of about 10 to about 30 stitches per 10cm, such as in the range of about 15 to about 20 stitches per 10 cm. In some embodiments, the length of the stitches may be from about 2.0 to about 8.0mm, and more preferably from about 4.0 to about 6.0 mm. In other cases, the bonding area of the stack can be between about 20 and about 60cm²Such as in the range of about 30 to about 40cm²And the area may include about 10 to about 40 stitches, such as about 15 to about 25 stitches.

The stitching of the stack of absorbent sheets may be performed using one thread, two threads, or three or more threads. Further, the sewing may be performed by any method commonly used for sewing cloth materials, such as single-thread lock stitch, chain stitch, loop stitch, etc. In a preferred embodiment of the method according to the invention, the stitching is performed by a single thread lock stitch. An exemplary lock-stitch is shown in fig. 1A, which generally comprises two separate threads (an upper thread 28 and a lower thread 29) interwoven together by cooperation of a sewing needle delivering the upper thread 28 into the stack 20 of material to be sewn and an auxiliary mechanism (typically a bobbin and a bobbin driver) providing the lower thread 29. The sewing needle forms a stitch eye 27 and passes an upper thread 28 therethrough. The cooperative movement of the sewing needle and the bobbin driver interweaves the upper and lower threads together to form a lock-stitch.

In other embodiments, the stack of absorbent sheets may be joined by chain stitches or loop stitches. In the case of using loop stitches to join the stack, the method may further comprise a further step of fixing adjacent portions of the seam created during the sewing step by means of a bond or by means of an adhesive, such that at least one stitch formed by the sewing may form a separate closed loop.

Referring now to fig. 2, in addition to a row of stitches 25, the stack 10 may further include a backing sheet 40 having portions that are bent over the top edge 22 of the stack to form a top end 42 and a face 43. The backing sheet may be formed of a material having a stiffness greater than that of the absorbent sheet, such as cardboard or the like. Stiffness of a material can be measured using the Taber (Taber) stiffness test described in ASTM standard D5650-97. As used herein, taber stiffness and taber stiffness units are typically reported in MD measurements of samples, and reported without reference units. For example, the taber stiffness of the backing sheet or strip may be about 2 times, such as about 2 times to about 20 times, the taber stiffness of the absorbent sheet material. In a particularly preferred embodiment, the backing sheet or strip and the absorbent sheet material differ not only in taber stiffness, but also are formed of different materials. For example, in one embodiment, the backing sheet or strip is formed from paperboard and has a Machine Direction (MD) stiffness (measured in taber stiffness units) greater than about 200cm gf and more preferably greater than about 250cm gf, and the absorbent sheet is a cellulosic tissue having a Machine Direction (MD) stiffness (measured in taber stiffness units) less than about 5.0 and more preferably less than about 3.0.

With continued reference to fig. 2, the backing sheet 40 includes a folded portion 41 that extends around and over the top edge 22 to form a joined top edge 42 and a face 43 that contacts the topmost sheet 12 of the stack 10. In this way, the bonding area 21 includes both a line of stitches 25 and the folded backing sheet 40. As shown in fig. 2, a row of stitches 25 is provided such that stitch eyes 27a, 27b and thread 28 do not contact the folded portion of backing sheet 40, although the invention is not limited thereto. In other embodiments, the row traces may be disposed on the folded portion. In other embodiments, the stitches are not arranged on the folded portion, but extend through the backing sheet.

While in certain embodiments it may be preferred to join the sheets using stitching alone, without other forms of attachment, such as adhesive or other mechanical attachment, in those embodiments where the backing sheet is folded to partially encapsulate the sheet, adhesive may be disposed between the folded backing sheet or strip and the absorbent sheet. Alternatively, a backing sheet may be provided, but not folded over the sheet, to provide stiffness to the stack. In such embodiments, the backing sheet may be adhesively attached to the bottom-most sheet in the stack, or the backing sheet may be bonded to the stack using stitching as described herein.

In other embodiments, the bonding element may comprise a strip instead of a bottom sheet. The straps typically do not extend along the back of the stack, but rather are disposed along the top edge and can be folded to extend along a portion of the front of the stack.

In certain embodiments, the backing sheet or tape may comprise means for mounting the stack of absorbent sheets to a surface. In other embodiments, a retainer may be provided, which may be made of metal, plastic, or other suitable material, and which is shaped to receive the joining edges of the stack to retain and hold the stack. The shape of the holder may be in the form of a flat slotted tube or channel member open at least at one end to receive the joining edges of the stack. The holder may provide means for fastening the holder to a vertical surface. In mounting the stack, the holder is fastened to a wall or the like, and then the spacer is engaged with the holder by inserting one end of the coupling edge into the channel.

Referring again to fig. 1, in addition to a row of stitches 25 that join a plurality of individual absorbent sheets 20 together to form the stack 10, the individual sheets 20 also include a row of perforations 30. The row of perforations 30 typically includes spaced apart individual perforation holes 31a, 31 b. The row of perforations 30 may be disposed parallel to and adjacent to the row of traces 25 as shown in fig. 1, although the invention is not limited thereto.

As described above, the row line trace includes a row of continuous trace apertures. Similarly, the row of perforations is also formed by a plurality of spaced apart perforations (referred to herein as perforation perforations), wherein at least a portion of the plurality of stitch perforations and a portion of the plurality of perforation perforations are arranged in pairs. For example, referring to fig. 3, a row of stitches 50 includes a continuous row of stitch eyes 51a, 51b with a line 52 disposed between adjacent stitch eyes. The stitch eyes 51a, 51b are arranged in a pattern comprising a first area 55, a second area 56 and a third area 57. The row of perforations 60 comprises a continuous row of perforation holes 61a, 62b comprising a first area 65, a second area 66 and a third area 67. In the embodiment shown, the stitch apertures 51 in the second region 56 and the perforation apertures 61 of the second region are arranged in pairs, with each stitch aperture having a corresponding perforation aperture.

In a particularly preferred embodiment, all the perforations forming a row of stitches and all the perforations forming a row of perforations are arranged in pairs. In certain embodiments, at least about 50%, more preferably at least about 60%, still more preferably at least about 70%, such as from about 50% to about 100%, more preferably from about 70% to about 100%, of the stitch apertures have a corresponding perforation aperture. In this manner, there is a one-to-one numerical correspondence between at least a portion of the plurality of perforation apertures and at least a portion of the plurality of stitch apertures.

In certain embodiments, not only are the stitch and perforation apertures arranged in pairs, but the rows of apertures are arranged generally parallel and adjacent to each other. In other embodiments, the stitch and perforation apertures are substantially vertically aligned with each other. For example, referring to fig. 1, stitch eyes 27 forming a row of stitches 25 and perforation eyes 31 forming a row of perforations 30 are arranged in pairs and are substantially vertically aligned with each other.

Although the stitch and perforation apertures may be vertically aligned, the invention is not so limited. In another embodiment, such as shown in fig. 2, there is a one-to-one numerical correspondence between stitch apertures 27 forming a row of stitches 25 and perforation apertures 31 forming a row of perforations 30, however, apertures 27, 31 are not vertically aligned. Thus, the stitch and perforation apertures may be vertically offset from each other, but still maintain a one-to-one numerical correspondence.

Further, while it is preferred that at least a portion of the stitch and perforation apertures are arranged in pairs, the size and shape of the apertures need not be similar. Thus, in certain embodiments, the stitch and perforation apertures have different shapes. In other embodiments, the stitch and perforation apertures have different areas. For example, referring to fig. 4A and 4B, non-limiting examples of shapes and sizes of stitch and perforation apertures are shown. For example, as shown in fig. 4A, a row of perforations 80 may include oval shaped perforation apertures 81a, 81b and a row of stitch lines 70 may include circular shaped stitch apertures 71a, 71 b. Alternatively, as shown in fig. 4B, the row of perforations 80 may include diamond-shaped perforation apertures 81a, 81B and the row of stitch lines 70 may include circular stitch apertures 71a, 71B.

In a particularly preferred embodiment, it may be preferred to form a row of perforations with perforations having a non-circular shape. For example, a row of perforations 80 may include oval shaped perforation holes 81a, 81b as shown in FIG. 4A, and oriented such that stress is concentrated at one end 82 when a user applies force (indicated by the arrow) to the sheet of material 90, making it easier to initiate and continue tearing along the perforation holes 80. Thus, less force may be required to tear the perforations and separate the sheets from the stack. In addition to the oval shaped perforations shown in fig. 4A, other suitable non-circular perforation shapes, such as triangular, diamond, or square shaped perforations, may be used to create stress concentrations and lower tear forces. For example, as shown in FIG. 4B, a row of perforations 80 may include diamond-shaped perforation holes 81a, 81B.

To achieve the paired arrangement of stitch and perforation, a sewing process using two, three or four needles may be used to make the stack of absorbent material. Sewing machines having multiple needles are well known in the art. In one embodiment, the sewing machine may include a double needle chuck supporting a pair of spaced apart needles arranged to form a double row of spaced apart eyelets. In the foregoing embodiments, the needles may be vertically aligned with one another, thereby creating similarly aligned stitch and perforation apertures, or they may be offset from one another. In other cases, a one-piece needle having two or more tines may be used, where one tine is used to make a line of stitches and the other tine is used to form a line of perforations. Whether the device uses a single needle or a one-piece needle having a plurality of tines, typically none of the needles or tines are provided with a line so as to form only perforations, which in turn form a row of perforations.

In other embodiments, additional rows of weakness or perforations may be formed in each of the plurality of absorbent sheets to allow portions of each of the absorbent sheets to be removed from the stack. For example, additional rows of perforations may be provided in each of the absorbent sheets to enable a user to remove only a portion of the sheets from the stack, such as a quarter or half of the sheets, while the remainder of the sheets remain bonded to the stack.

The bonded and perforated stack of absorbent sheets can be formed from a wide variety of absorbent sheet materials. For example, the absorbent sheet has a basis weight (measured using TAPPI test method T-220) of greater than about 10 grams per square meter (gsm), such as from about 10 to about 100gsm, more preferably from about 15 to about 70gsm, and a caliper (using an EMVECO 200-a Microgage automatic micrometer (EMVECO, inc., Newberg, OR) according to TAPPI test method T402) of greater than about 200 μm, such as from about 200 to about 2000 μm. Further, the vertical absorbent capacity (measured as described in U.S. Pat. No. 7,449,085) of the sheet can be greater than about 4.0g/g, such as from about 4.0 to about 12g/g, and more preferably from about 6.0 to about 10 g/g.

In other embodiments, the absorbent sheet has a dry geometric mean tensile strength (measured according to TAPPI test method T-494 om-01) of greater than about 500g/3 ", and more preferably greater than about 750 g/3", and still more preferably greater than about 1,000g/3 ", such as from about 500 to about 3,500 g/3", and more preferably from about 1,000 to about 2,500g/3 ". In this manner, the absorbent sheets have sufficient tensile strength to withstand the forces required to separate the individual sheets from the stack.

The absorbent sheet material may comprise one or more layers and may be folded or unfolded. In certain embodiments, individual sheets in the stack can be folded to form a folded sheet having multiple layers. When a single sheet is removed from the stack, it can be unfolded to provide a single absorbent sheet having a surface area greater than the surface area of the stack.

Thus, in embodiments, each absorbent sheet in the stack may be in a folded configuration, such as a half-fold or quarter-fold of the sheet. For example, a sheet material having a half-folded configuration may have four distinct edges, a first end, and a second end opposite the first end. A binding element is disposed along the first end and a row of perforations is disposed adjacent the binding element to enable the sheets to be individually removed from the stack. Other folded configurations may also be useful herein, such as Z-fold or C-fold.

Further, it should be understood that the sheets and resulting stack may take any number of different shapes, and although it may be desirable for two or more edges of the sheets to be aligned with one another, the invention is not so limited. In addition, the size of each sheet and the number of sheets in the stack correspond to the number of available units needed in the finished tissue product.

To make a bonded and perforated stack of absorbent sheets according to the present invention, a plurality of sheets are cut to size and stacked in a facing manner. In a particularly preferred embodiment, the sheets are stacked in register with each other, i.e. the machine direction of the sheets are in register with each other, and more preferably in register such that the subsequent stitches are substantially perpendicular to the machine direction of the sheets. The double sewing needle having the first and second tines is adapted to be displaced in a vertical direction by the driving means. The first tine points towards its tip and, if necessary, the thread is joined to the tip of the needle by means of a suitable joining device. The thread may be delivered from a coil of thread. After joining the thread on the tip, the needle is moved toward and through the stack of sheets to form a stitch aperture and thread through the aperture. The shape and size of the stitch aperture generally corresponds to the shape and size of the first tine. Simultaneously, the second tines move toward and through the stack of sheets to form perforation apertures.

While the present absorbent sheet stack has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. Accordingly, the scope of the invention should be assessed as that of the appended claims and any equivalents thereto and as that of the foregoing embodiments:

in a first embodiment, the present disclosure provides an absorbent sheet stack comprising: a plurality of absorbent sheets having a machine direction and a cross-machine direction and stacked in a facing manner to form a stack of absorbent sheets, the stack having a top edge and a bottom edge; a joining element for joining the sheets together to form a stack disposed adjacent the top edge of the stack, the joining element comprising a row of stitches including a plurality of spaced apart stitch apertures and a thread disposed between a first stitch aperture and a second stitch aperture; and a row of perforations comprising a plurality of spaced apart perforation apertures, wherein at least a portion of the perforation apertures and the stitch apertures are arranged in pairs.

In a second embodiment, the present disclosure provides the stack of absorbent sheets according to the first embodiment, wherein the absorbent sheets have a basis weight of greater than about 10 grams per square meter (gsm), a geometric mean tensile strength (GMT) of from about 500 to about 3,500g/3 ", and a vertical absorbent capacity of greater than about 4.0 g/g.

In a third embodiment, the present disclosure provides the stack of absorbent sheets according to the first or second embodiment, wherein the plurality of absorbent sheets comprises half-folded or quarter-folded absorbent sheets.

In a fourth embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to third embodiments, wherein the plurality of absorbent sheets comprises half-folded or quarter-folded absorbent sheets.

In a fifth embodiment, the present disclosure provides the stack of absorbent sheets as in any one of the first to fourth embodiments, wherein the stitch aperture has a first shape and the perforation aperture has a second shape, wherein the first shape and the second shape are different.

In a sixth embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to fifth embodiments, wherein the stitch apertures have a circular, semi-circular, or elliptical shape and the perforation apertures have a rectangular, square, diamond, elliptical, or linear shape.

In a seventh embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to sixth embodiments, wherein the plurality of spaced apart stitch apertures and the plurality of spaced apart perforation apertures are each substantially linear and arranged parallel to each other.

In an eighth embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to seventh embodiments, further comprising a backing sheet or tape, wherein the taber stiffness of the backing sheet or tape is greater than the taber stiffness of the plurality of absorbent sheets.

In a ninth embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to eighth embodiments, further comprising a backing sheet or tape folded over the top edge of the stack of absorbent sheets to form a portion of the bonding element.

In a tenth embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to ninth embodiments, wherein the stack is substantially free of adhesive.

In an eleventh embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to tenth embodiments, further comprising a second row of stitches comprising a plurality of spaced apart stitch apertures and a thread disposed between the first and second stitch apertures.

In a twelfth embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to eleventh embodiments, wherein about 50% to about 100% of the stitch and perforation apertures are arranged in pairs.

In a thirteenth embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to twelfth embodiments, wherein about 75% to about 100% of the stitch and perforation apertures are arranged in pairs.

In a fourteenth embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to thirteenth embodiments, wherein there is a one-to-one correspondence of the perforation and stitch apertures.

In a fifteenth embodiment, the present disclosure provides the stack of absorbent sheets of any one of the first to fourteenth embodiments, wherein the pairs of stitch and perforation apertures are substantially vertically aligned.