WO2007111990A2

WO2007111990A2 - Method and apparatus for forming an absorbent core

Info

Publication number: WO2007111990A2
Application number: PCT/US2007/007222
Authority: WO
Inventors: John J. Walter; John D. Litvay
Original assignee: Walter John J; Litvay John D
Priority date: 2006-03-24
Filing date: 2007-03-24
Publication date: 2007-10-04
Also published as: WO2007111872A2; WO2007111990A3

Abstract

An apparatus and a method for making an absorbent core from a tow-based absorbent core composite. The tow-based absorbent core composite is made using a forming apparatus. The tow-based absorbent core composite is fed into a crimping device. The crimping device generates a pattern on the tow-based absorbent core composite. The tow-based absorbent core is cut into absorbent cores using a cutting device. The apparatus excludes a set of calender rolls used for compressing the tow-based absorbent core composite. The method eliminates a step of compressing the tow-based absorbent core composite using the set of calender rolls.

Description

METHOD AND APPARATUS FOR FORMING AN ABSORBENT CORE

CROSS REFERENCE TO RELATED APPLICATIONS The present application claims priority to US provisional application Serial No. 60/785,455, filed March 24, 2006, and this application is herein incorporated by reference in its entirety.

BACKGROUND The present invention relates generally to a system and a method for manufacturing absorbent cores. More specifically, the present invention relates to a system and a method for forming tow-based absorbent cores.

Generally, disposable absorbent garments such as infant diapers, training pants, adult incontinence products, feminine hygiene products and other such products are constructed with a moisture-impervious outer backsheet, a moisture-pervious body- contacting inner topsheet, and an absorbent core sandwiched between the topsheet and the backsheet.

Much effort has been expended to find cost-effective methods and apparatus for manufacturing of absorbent cores with good liquid absorbency and retention of liquid under pressure. The absorbent cores are made from absorbent core composites, and the integrated to absorbent garments. To improve the quality of the absorbent core composite, particles of superabsorbent particulates (SAP) are distributed within the absorbent core composites comprising a fibrous web of fluffed pulp material, tow fiber and the like. The introduction of tow fiber into the absorbent core composites has further improved liquid absorbency and liquid retention capacity of the absorbent core composites. These absorbent core composites have improved SAP efficiency and higher density. Moreover, higher density of tow fibers result into thinner absorbent core composites. Such absorbent cores are disclosed, for example, in U.S. Statutory Invention Registration No. H 1,565 to Brodof et al., which is incorporated by reference herein in its entirety and in a manner consistent with the present invention.

Generally, known processes for creating a conventional tow-based absorbent core composite use a large forming apparatus to blend the SAP with the tow fiber, and then convey this blend onto a vacuum draw roll or screen by using a vacuum. One or more casing sheets are supplied to encase the blend of SAP and tow fiber. The vacuum draw roll has forming pockets that form the absorbent core composites.

Conventionally, an absorbent core has been made by crimping and cutting of an absorbent core composite. Before cutting, the absorbent core composite is compressed using one or more calender rolls. Since, the calender roll assemblies are normally about 2 meters in length, therefore, almost about 2 meters of absorbent core composite is held by the calender rolls. Each time the manufacturing line of absorbent core composite is shutdown for any reasons, about 2 meters of absorbent core composite is wasted before restarting of the manufacturing line. Even, the presence of calender rolls increases the size, weight, and cost of manufacturing line or manufacturing unit of the absorbent core composite or absorbent core. Therefore, there exits a need to modify the manufacturing line in order to prevent the wastage of absorbent core composite, reduce the cost of absorbent core, and to reduce the size, weight and cost of manufacturing line or unit.

These are just a few of the disadvantages of the prior art which the preferred embodiments seek to address. The foregoing description of certain material, methods and systems with their attendant disadvantages in no way is meant to infer that the present invention excludes such materials, methods, and systems. Indeed, certain embodiments of the invention may solve some of the aforementioned disadvantages, yet utilize the same or similar materials, methods and/or systems.

BRIEF DESCRIPTION

It would be desirable to provide an apparatus and method for forming tow-based absorbent cores, deriving special advantages tow-based materials may provide over the fluff type absorbent cores. It would further be desirable for such an apparatus and method to be efficient, easy to operate, and capable of operating at high line speeds. It would furthermore be desirable to provide an apparatus and a method to prevent the wastage of absorbent core composite before restarting of manufacturing line and to reduce the size, weight and cost of the manufacturing line. In accordance with these and other features of various embodiments of the invention, there is provided an apparatus and method for forming tow-based absorbent cores.

In accordance with various embodiments, the present invention provides an apparatus and a method of making an absorbent core. The apparatus comprises a cutting device for cutting an absorbent core composite. The absorbent core composite comprises tow fiber. The absorbent core composite is cut into one or more absorbent cores. However, the apparatus excludes one or more calender rolls, wherein, each of the one or more calender rolls is used for compressing the absorbent core composite.

DRAWINGS

The foregoing and other advantages and features of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:

FIG. 1 illustrates a prior art apparatus for making an absorbent core.

FIG. 2 illustrates an apparatus for making an absorbent core according to various embodiments of the present invention.

DETAILED DESCRIPTION

As used herein, the term "absorbent garment" or "garment" refers to garments that absorb and contain exudates, and more specifically, refers to' garments that are placed against or in proximity to the body of the wearer to absorb and contain the various exudates discharged from the body. A non-exhaustive list of examples of absorbent garments includes diapers, diaper covers, disposable diapers, training pants, feminine hygiene products and adult incontinence products. The term garment includes all variations of absorbent garments, including disposable absorbent garments that are intended to be discarded or partially discarded after a single use (i.e., they are not intended to be laundered or otherwise restored or reused) and unitary disposable absorbent garments that have essentially a single structure (i.e., do not require separate manipulative parts such as a diaper cover and insert). As used herein, the term "diaper" refers to an absorbent garment generally worn by infants and incontinent persons about the lower torso. The claims are intended to cover all of the foregoing classes of absorbent garments, without limitation, whether disposable, unitary or otherwise. The invention will also be understood to encompass, without limitation, all other types of absorbent structure that may comprise an absorbent core, whether described herein or not. Absorbent garments and diapers may have a number of different constructions. In each of these constructions it is generally the case that an absorbent core is disposed between a liquid pervious, body-facing topsheet, and a liquid impervious, exterior facing backsheet. In some cases, one or both of the topsheet and backsheet may be shaped to form a pant-like garment. In other cases, the topsheet, backsheet and absorbent core may be formed as a discrete assembly that is placed on a main chassis layer and the chassis layer is shaped to form a pant-like garment. The garment may be provided to the consumer in the fully assembled pant-like shape, or may be partially pant-like and require the consumer to take the final steps necessary to form the final pant-like shape. In the case of training pant-type garments and most adult incontinent products, the garment is provided fully formed with factory-made side seams and the garment is donned by pulling it up the wearer's legs. For clarity, the present invention is described herein only with reference to a diaper-type garment in which the topsheet, backsheet and absorbent core are assembled into a structure that forms a pant-like garment when secured on a wearer using fastening devices, although the invention may be used with other constructions. Throughout this description, the expression "tow fibers" relates in general to any continuous fiber. Non-limiting examples of suitable tow fibers includes among others cellulose esters, polyolefin, polypropylene, and the like.

FIG. 1 illustrates a prior art apparatus 100 used for making one or more absorbent cores. Prior art apparatus 100 comprises a forming apparatus 102, a set of calender rolls 1 10, a crimping device 1 12, and a cutting device 114. Forming apparatus 102 is used to make an absorbent core composite 148.

Forming apparatus 102 comprises, a tow supply 120, a tow jet assembly 122, a vibratory feeder 124, a first casing sheet supply 126, a second casing sheet supply 128, and a vacuum draw roll 130. The tow supply 120 is provided along a first path to tow jet assembly 122. The tow supply 120 enters the tow jet assembly 122 and is opened in preparation for being incorporated into the absorbent cores composite 148. Air or other gas are projected into the tow jet assembly 122 to impinge upon the tow fiber to thereby separate the fibers and "bloom" or open the tow fiber. Such forming apparatus are disclosed, for example, in U.S. Patent No. 6, 923,926 to J. Walter et al., which is incorporated by reference herein in its entirety and in a manner consistent with the present invention.

After the opened tow exits the tow jet assembly 122, vibratory feeder 124 delivers superabsorbent particles to the opened tow, and the tow/SAP composite is encased between the first casing sheet supply 126 and second casing sheet supply 128. Alternatively, the tow/SAP composite is also encased within a fold in a single casing sheet. The opened tow is laid onto first casing sheet supply 126 before the SAP is fed to the opened tow, then the second casing sheet supply 128 is laid on the tow/SAP composite to form absorbent core composite 148 . The absorbent core composite 148 is assembled in four steps that take place as the various parts of the forming apparatus 102 are pulled onto the rotating vacuum draw roll 130. In the first step, which takes place at location A, the first casing sheet supply 126 is drawn onto the vacuum draw roll 130. In the second step, at location B, the opened tow is drawn onto the vacuum draw roll 130 to overlay the first casing sheet supply 126 after being pulled out of the tow jet assembly 122. In the third step, at location C, a supply of SAP is deposited onto the opened tow by the vibratory feeder 124. And in the fourth step, at location D, the second casing sheet supply 128 is brought in to overlie the first casing sheet supply 126, and deposited tow/SAP composite. In other prior art apparatuses, these steps are performed using equipment other than that specifically described herein, and also performed in various different orders, with some of the steps being rearranged, omitted or combined, or with additional steps being performed.

Further, a lay on roll 140 is used to press the second casing sheet supply 128 against the tow/SAP composite and the first casing sheet supply 126. The lay on roll 140 helps flatten the absorbent core composite 148 and improves the edge seals between the first and second casing sheet supplies 126, 128.

The absorbent core composite 148 made from forming apparatus 102 is cut into one or more absorbent cores. More particularly, absorbent core composite 148 is fed into set of calender rolls 1 10 before cutting. Set of calender rolls 1 10 compresses absorbent core composite 148 in order to make a thinner absorbent core composite. The thinner absorbent core composite results into thinner absorbent cores. Normally, set of calender rolls 110 is about 2 meters of length. Thus, a portion of absorbent core composite 148 of about 2 meters length is held by set of calender rolls 1 10 during manufacturing process. During this manufacturing process, whenever, manufacturing line is shutdown and restarted, the portion of absorbent core composite 148 held by the set of calender rolls 1 10 goes as waste. Therefore, each time the manufacturing line restarted, the absorbent core composite of about 2 meters in length goes as waste. This is very undesirable. Further, absorbent core composite 148 is also fed into crimping device 112 before cutting into one or more absorbent cores. Crimping device 112 generates patterns on absorbent core composite 148. Then, absorbent core composite 148 is cut into one or more absorbent cores using cutting device 1 14.

The prior art apparatus 100 has been in practice since very long. However, set of calender rolls 110 are effective only when absorbent core composite comprises discontinuous fibers such as wood pulp, fluff fibers, and the like. Since the discontinuous fibers have relatively lesser density, application of set of calender rolls 1 10 increases density of absorbent core composite resulting into a thinner absorbent core composite. On the other hand, tow fibers are continuous fibers having higher density compared to discontinuous fibers such as wood pulp, fluff fibers, and the like. Moreover, the density of tow fibers does not change by compressing from set of calender rolls 110. Therefore, the thickness of an absorbent core composite comprising tow fibers does not change even after the compression by set of calender rolls 110. Therefore, the absorbent core composite comprising tow fibers need not to be compressed by set of calender rolls 110. FIG. 2 illustrates an apparatus 200 for making one or more absorbent core. Apparatus 200 comprises forming apparatus 102, crimping device 1 12, and cutting device 114. Essentially, apparatus 200 excludes set of calender rolls 110 (as shown in fig. 1). Absorbent core composite 148 is made from forming apparatus 102. Here, absorbent core composite 148 comprises tow fibers. Preferable examples of tow fibers include among others cellulose esters, polyolefin, polypropylene, and the like. Since, set of calender rolls 110 is excluded from the apparatus 200, absorbent core composite 148 is directly fed into crimping device 112. Essentially, a step of compressing of absorbent core composite 148 is eliminated. Crimping device 112 generates patterns on absorbent core composite 148. Then, absorbent core composite 148 is fed into cutting device 114 to cut into one or more absorbent cores. However, in another embodiment of the present invention, absorbent core composite 148 may directly be fed into cutting device 114 without crimping. In alternative embodiment, cutting device 114 may further comprise a crimping device. Here, the crimping device firstly creates patterns on absorbent core composite 148. Then, absorbent core composite 148 is cut into one or more absorbent cores. It will be recognized within the scope of the present invention that absorbent core composite 148 may also be made by various different apparatus and different methods known in the art. The absorbent core made from apparatus 200 may be used in construction of absorbent garment as discussed previously. Apparatus 200 has various advantages over prior art apparatus 100. Each time, apparatus 200 is shutdown and restarted, about 2 meters of length of absorbent core composite is saved. Size and weight of apparatus 200 is less than size and weight of prior art apparatus 100. Consequently the cost of apparatus 200 is less than the cost of apparatus 100. Even the cost of absorbent garment decreases as the wastage of absorbent core composite is reduced.

Other embodiments, uses, and advantages of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. Furthermore, the present invention may be used in combination with any suitable prior art apparatus or methods, and any description herein of drawbacks or limitations of the prior art are not to be understood as limiting the scope of the present invention to necessarily exclude the inclusion of such prior art apparatus or methods with the present invention. The specification should be considered exemplary only, and the scope of the invention is accordingly intended to be limited only by the following claims and equivalents thereof.

Claims

1. An apparatus for making an absorbent core, the apparatus comprising a cutting device for cutting an absorbent core composite into at least one absorbent core, wherein the apparatus excludes a set of calender rolls used for compressing the absorbent core composite, and wherein the absorbent core composite comprises tow fiber.

2. The apparatus of claim 1 further comprising a forming device, the forming device being used for formation of the absorbent core composite.

3. The apparatus of claim I further comprising a crimping device for crimping of the absorbent core composite before cutting the absorbent core composite.

4. The apparatus of claim 1, wherein the cutting device further comprises a crimping device used for crimping of the absorbent core composite before cutting the absorbent core composite.

5. A method for making an absorbent core, the method comprising: a. providing an absorbent core composite comprising tow fiber; and b. cutting the absorbent core composite into at least one absorbent core, wherein the method eliminates a step of compressing the absorbent core composite using a set of calender rolls.

6. The method of claim 5, wherein the step of providing an absorbent core composite comprises making the absorbent core composite, the absorbent core composite made using a forming device.

7. The method of claim 5 further comprises a step of crimping the absorbent core composite, the crimping being done before cutting the absorbent core composite.

8. An absorbent garment comprising an absorbent core, wherein the absorbent core is made using an apparatus comprising a cutting device for cutting an absorbent core composite, the absorbent core composite comprising tow fiber, the absorbent core composite being cut into at least one absorbent core, wherein the apparatus excludes a set of calender rolls used for compressing the absorbent core composite.

9. The absorbent garment of claim 8, wherein the tow fiber is polyolefin fiber.

10. The absorbent garment of claim 8, wherein the tow fiber is polypropylene fiber.

1 1. The absorbent garment of claim 8 further comprising: a. a topsheet; and b. a backsheet, wherein the absorbent core is disposed between the topsheet and the backsheet.

12. An absorbent garment comprising an absorbent core, wherein the absorbent core is made using a method comprising: i. providing an absorbent core composite comprising tow fiber; and H. cutting the absorbent core composite into at least one absorbent

^•^ore. wherein, the method eliminates a step of compressing the absorbent core composite using a set of calender rolls.

13. The absorbent garment of claim 12, wherein the tow fiber is polyolefin fiber.

14. The absorbent garment of claim 12, wherein the tow fiber is polypropylene fiber.

15. The absorbent garment of claim 12 further comprising: a. a topsheet; and b. a backsheet, wherein the absorbent core is disposed between the topsheet and the backsheet.

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