WO1999063852A1 - Mechanical restoration of a deformed loop structure - Google Patents

Abstract

An improved process for making disposable diapers, and the like, having hook-and-loop fastening systems, and disposable diapers made by the improved process. The loop structure of the hook-and-loop fastening system used in this invention is substantially free of article attachment adhesive and comprises loop elements affixed to a support structure. The loop elements are deformed when the loop structure is wound onto a parent roll (51). At least a portion of the deformed loop elements (4') are restored to essentially their original, undeformed, state after the loop structure is unwound from the parent roll. The restoration is accomplished by contacting the loop elements (4') with a mechanical restoration device (52) which comprises either a brush or a scarfing surface. The brush preferably has a plurality of bristles having an average free length greater than about three times the average undeformed height of the loop elements and an average bending modulus less than the average modulus of elasticity of the loop elements. The scarfing surface preferably has an average roughness of at least about 500 RMS.

Description

MECHANICAL RESTORATION OF A DEFORMED LOOP

STRUCTURE

Background of the Invention

Field of the Invention

This invention relates to hook-and-loop fastening systems. More particularly, it relates to manufacturing processes for articles comprising hook-and-loop fastening systems. Even more particularly, it relates to an improvement in continuous processes for the attachment of loop structures of

hook-and-loop fastening systems to articles of manufacture.

Background Art

The general public, frequently erroneously, refers to the ubiquitous

hook-and-loop fastening system as "Velcro®" regardless of the manufacturer or the technical form of the system. The various hook-and-loop fastening

systems have found extensive use wherever repeated attachment and

reattachment, fastening and unfastening are required. Articles of clothing such as jackets and shoes commonly use hook-and-loop systems. One major

use of hook-and-loop systems is in disposable diapers. (In this particular

application the hook-and-loop system is sometimes called a "mechanical

fastening" system.) While the present invention can be used in a wide

variety of applications, and while its use in such wide variety is not disclaimed, for the sake of simplicity it will be discussed and described in

conjunction with its use in the manufacture of disposable diapers.

There are numerous patents in which various hook-and-loop systems

are described as well as patents in which various methods of affixing the

hook-and-loop systems to disposable diapers are described.

Examples of patents describing hook-and-loop systems include U.S.

Patent 4,846,815 issued to Scripps on July 11, 1989; U.S. Patent 4,894,060

issued to Nestegard on January 16, 1990; and U.S. Patent 4,973,326 issued

to Wood et al on November 27, 1990.

Examples of patents describing disposable diapers which can benefit

from use of the present invention include U.S. Patent 3,860,003 issued to

Kenneth B. Buell on January 14, 1975; U.S. Patent 5,151,092 issued to Buell

on September 9, 1992; and U.S. Patent 5,221,274 issued to Buell on June 22,

1993; each of which is incorporated herein by reference. It will be clear to

those skilled in the art that other diaper structures can also benefit from use

of the present invention.

Summary of the Invention

This invention is of an improvement in continuous processes for

manufacturing articles comprising hook-and-loop fastening systems. The

improvement comprises the steps of: a.) Providing a loop structure comprising a plurality of loop

elements, the loop elements being affixed to a support substrate, the support

substrate being substantially free of article attachment adhesive;

b.) Deforming at least a portion of the loop elements by winding the

loop structure upon itself to form a parent roll;

c.) Unwinding the loop structure from the parent roll;

d.) Restoring at least a portion of the deformed loop elements by

contacting the deformed loop elements with a mechanical restoration device;

and

e.) Introducing the loop structure comprising the restored loop

elements into the continuous process.

The restoration device can be a brush having particular properties or a

solid surface having specified roughness characteristics.

Brief Description of the Drawings

To aid in the understanding of the invention, the following non-

limiting drawings are presented. The thickness of certain materials has

been exaggerated for clarity.

FIG. 1 is a cross sectional view of a generic hook-and-loop fastening

system. It is intended to represent a wide variety of such systems while not

illustrating any one system with particularity. In this illustration the hooks

are not engaged with the loops. Fig. 2 is a perspective view of a generic disposable diaper and

illustrates a significant use of the hook-and-loop fastening system used with

the present invention. It is intended to represent a wide variety of disposable

diapers while not illustrating any one disposable diaper with particularity.

Fig. 3 is a cross sectional view of the generic loop structure portion of

the generic hook-and-loop fastening system illustrated in Fig. 1. Certain

dimensions have been indicated.

Fig. 4 is the cross sectional view of the generic loop structure

illustrated in Fig. 3 in which the generic loop elements have been deformed.

Fig. 5 is a schematic representation of the process of the present

invention.

Fig. 6 is a perspective view of a preferred mechanical restoration

device used in the present invention.

Fig. 7 is a perspective view of an alternate preferred mechanical

restoration device used in the present invention.

Fig 8 is a perspective view of an alternate preferred mechanical

restoration device used in the present invention.

Fig 9 is a perspective view of an alternate preferred mechanical

restoration device used in the present invention.

Detailed Description of the Invention

While this specification concludes with claims particularly pointing

out and distinctly claiming that which is regarded as the invention, it is anticipated that the invention can be more readily understood through

reading the following detailed description of the invention and study of the

included drawings and example.

This invention is of an improvement in continuous processes for

manufacturing articles comprising hook-and-loop fastening systems. The

improvement comprises the steps of:

a.) Providing a loop structure comprising a plurality of loop

elements, the loop elements being affixed to a support substrate, and the

support substrate being substantially free of article attachment adhesive;

b.) Deforming at least a portion of the loop elements by

winding the loop structure upon itself to form a parent roll;

c.) Unwinding the loop structure with its deformed loop

structures from the parent roll;

d.) Restoring at least a portion of the deformed loop elements

by contacting the deformed loop elements with a mechanical restoration

device; and

e.) Introducing the loop structure comprising the restored loop

elements into the continuous process.

The restoration device can be a brush having particular properties or a

solid surface having specified roughness characteristics.

Fig. 1 is a cross sectional view of generic hook-and-loop fastening

system 1. As noted above, illustrated fastening system 1 is intended to

represent a wide variety of such systems while not illustrating any one system with particularity. U.S. Patents 4,846,815; 4,894,060; and 4,973,326

mentioned above, and which are incorporated herein by reference, describe

hook structures, loop structures, and hook-and-loop fastening systems which

can be used in the present invention. Additional references describing hook

structures and loop structures include U.S. Patent 5,019,073 issued to

Roessler et al on May 28, 1991; U.S. Patent 5,318,555 issued to Siebers et al

on June 7, 1994; and PCT Publication WO 96/13996 issued to Thomas on

May 17, 1996. All the foregoing references are incorporated herein by

reference.

Hook-and-loop fastening system 1 comprises loop structure 2 and hook

structure 3. Loop structure 2, in turn, comprises a plurality of loop elements

4 affixed (by means not shown) to loop support substrate 5. Hook structure

3, in turn, comprises hook elements 7 affixed (by means not shown) to hook

support substrate 8. In this cross sectional view, hooks 7 are shown

disengaged from loop element 4. It is to be understood that when fastening

system 1 is in use, hooks 7 cooperate with loop element 4 to effect releasable

union of structures 2 and 3. Reference numerals 6 and 9 indicate,

respectively, loop structure attachment surface and hook structure

attachment surface. Loop structure 2 will, in use, be affixed at attachment

surface 6 to an article of manufacture 11. Hook structure 3 will, in use, be

affixed at attachment surface 9 to an article of manufacture 12. In this

orientation, then, fastening system 1 can be used to releasable join the two

articles of manufacture 11 and 12. Alternatively, articles of manufacture 11 and 12 can be envisioned as being different parts of the same overall article

of manufacture. In this orientation, then, fastening system 1 can be used to

releasable secure the two parts of the overall article to one another.

Fig. 2 is a perspective view of simplistic, generic disposable diaper 21.

As noted above, illustrated disposable diaper 21 is intended to represent a

wide variety of such disposable diapers while not illustrating any one diaper

with particularity. U.S. Patents 3,860,003, 5,151,092, and 5,221,274

mentioned above and incorporated herein by reference, describe disposable

diapers which can benefit from the use of the present invention. The present

invention, however, finds application in other diaper designs.

Diaper 21 comprises outer liquid impermeable backsheet 22 and inner

liquid permeable topsheet 23. An absorbent element, not illustrated, is

interposed between backsheet 22 and topsheet 23. Hook structures 3 are

affixed to rear portion 24 of diaper 21 by means not illustrated. In this

position, loop structure 2 provides what those skilled in the art sometimes

refer to as a "landing zone" for hook elements 7 of hook structures 3. Hook

structures 3 are affixed to diaper 21 with a plurality of hook elements 7

oriented as shown. Loop structure 2 is affixed to front portion 25 of diaper 21

by means not illustrated. A plurality of loop elements 4 are oriented as

shown. In use, diaper 21 is applied to a human wearer, such as an infant, by

placing crotch region 26 of diaper 21 between the legs of the wearer with

front portion 25 adjacent the front of the wearer and rear portion 24 adjacent

the back of the wearer. Each rear side margin 27 is then folded about the hips and thighs of the wearer. Hook elements 7 are engaged with loop

elements 4 to secure diaper 21 in position about the wearer.

Backsheet 22 is impervious to liquids (e.g., urine) and comprises, for

example, a thin plastic film such as a thermoplastic film having a thickness

of about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils). Suitable

backsheet films include those manufactured by Tredegar Industries Inc. of

Terre Haute, IN and sold under the trade names X15306, X10962 and

X10964. Other suitable backsheet materials can include breathable

materials which permit vapors to escape from the diaper 21 while still

preventing exudates from passing through the backsheet 22. Exemplary

breathable materials include materials such as woven webs, nonwoven webs,

composite materials such as film-coated nonwoven webs, and microporous

films such as manufactured by Mitsui Toatsu Co., of Japan under the

designation ESPOIR NO and by EXXON Chemical Co., of Bay City, TX,

under the designation EXXAIRE. Suitable breathable composite materials

comprising polymer blends are available from Clopay Corporation,

Cincinnati, OH under the name HYTREL blend P18-3097. Such breathable

composite materials are described in greater detail in PCT Application No.

WO 95/16746, published on June 22, 1995 in the name of E. I. DuPont and

copending U.S. Patent Application Serial No. 08/744,487, filed on November

6, 1996 in the name of Curro. Other breathable backsheets including

nonwoven webs and apertured formed films are described in U.S. Patent 5,571,096 issued to Dobrin et al. on November 5, 1996. Each of the foregoing

references is incorporated herein by reference.

The whole of backsheet 22, or any portion thereof, can be elastically

extensible in one or more directions. Extensible webs suitable for the present

invention are described in U.S. Patent 5,518,801 issued to Chappell, et, al.

on May 21, 1996, which is incorporated herein by reference. In alternate

embodiments, backsheet 22 comprises elastomeric films, foams, strands, or

combinations of these or other suitable materials with nonwovens or

synthetic films.

The present invention is not dependent on the use of any particular

backsheet. The foregoing is presented for purposes of illustration and not

limitation.

Topsheet 23 is preferably compliant, soft feeling, and non-irritating to

the wearer's skin. Further, at least a portion of topsheet 23 is liquid

pervious, permitting liquids to readily penetrate through its thickness.

Topsheet 23 can be manufactured from a wide range of materials such as

porous foams; reticulated foams; formed plastic films such as apertured

plastic films;, and woven or nonwoven webs of natural fibers (e.g., wood or

cotton fibers), synthetic fibers (e.g., polyester or polypropylene fibers), or a

combination of natural and synthetic fibers. If topsheet 23 includes fibers,

the fibers can be spunbond, carded, wet-laid, meltblown, hydroentangled, or

otherwise processed as is well known in the art. One suitable topsheet

material comprises a web of staple length polypropylene fibers and is manufactured by Veratec, Inc., a Division of International Paper Company,

of Walpole, Massachusetts under the designation P-8.

Formed films suitable for topsheet 23 are described in U.S. Patent

3,929,135 issued to Thompson on December 30, 1975; U.S. Patent 4,324,246

issued to Mullane, et al. on April 13, 1982; U.S. Patent 4,342,314 issued to

Radel, et al. on August 3, 1982; U.S. Patent 4,463,045 issued to Ahr, et al. on

July 31, 1984; and U.S. Patent 5,006,394 issued to Baird on April 9, 1991.

Other suitable topsheets can be made in accordance with U.S. Patents

4,609,518 and 4,629,643 which issued to Curro et al. on September 2, 1986

and December 16, 1986, respectively. All of the foregoing patents are

incorporated herein by reference. Suitable formed films are available from

The Procter & Gamble Company of Cincinnati, Ohio as "DRI-WEANE" and

from Tredegar Corporation of Terre Haute, Indiana as "CLIFF-T."

Preferably, topsheet 23 is made of a hydrophobic material or is treated

so as to be hydrophobic in order to isolate the wearer's skin from liquids

contained in the absorbent element. If topsheet 23 is made of a hydrophobic

material, preferably at least the upper surface of topsheet 23 is treated to be

hydrophilic so that liquids will transfer through the topsheet more rapidly.

This diminishes the likelihood that body exudates will flow off topsheet 23

rather than being drawn through topsheet 23 and being absorbed by the

absorbent element. Topsheet 23 can be rendered hydrophilic by treating it

with a surfactant or by incorporating a surfactant into the topsheet material.

Suitable methods for treating topsheet 23 with a surfactant include spraying topsheet 23 with the surfactant and immersing the material into the

surfactant. A more detailed discussion of such a treatment and

hydrophilicity is contained in U.S. Patents 4,988,344 and 4,988,345 issued to

Reising, et al. on Jan. 29, 1991. A more detailed discussion of suitable

methods for incorporating surfactant in the topsheet can be found in U.S.

Statutory Invention Registration No. H1670, published on July 1, 1997 in

the names of Aziz et al. Each of the foregoing references is incorporated

herein by reference. Alternatively, topsheet 23 can include an apertured web

or film which is hydrophobic. This can be accomplished eliminating the

hydrophilizing treatment step from the production process or by applying a

hydrophobic treatment to topsheet 23. Materials such as

polytetraflouroethylene compounds and a hydrophobic lotion composition (as

described below) are suitable. In such embodiments, it is preferred that the

apertures be large enough to allow the penetration of aqueous fluids like

urine without significant resistance.

Any portion of topsheet 23 can be coated with a lotion as is known in

the art. Examples of suitable lotions include those described in U.S. Patent

5,607,760 issued to Roe on March 4, 1997; U.S. Patent 5,609,587 issued to

Roe on March 11, 1997; U.S. Patent 5,635,191 issued to Roe et al. on June 3,

1997; and U.S. Patent 5,643,588 issued to Roe et al. on July 1, 1997. The

lotion can function alone or in combination with another agent as the

hydrophobizing treatment described above. The topsheet can also include or

be treated with antibacterial agents, examples of which are disclosed in PCT Publication No. WO 95/24173 published on September 14, 1995 in the name

of Johnson. Further, the whole of topsheet 23, the whole of backsheet 22 or

any portion of either can be embossed or matte finished to provide a more

cloth like appearance.

The present invention is not dependent on the use of any particular

topsheet. The foregoing is presented for purposes of illustration and not

limitation.

The absorbent element, which is mentioned above and which, as

noted, is not illustrated in Fig. 2, comprises any absorbent material which is

generally compressible, conformable, non-irritating to the wearer's skin, and

capable of absorbing and retaining liquids such as urine and other certain

body exudates. The absorbent element can be manufactured in a wide

variety of sizes and shapes (e.g., rectangular, hourglass, "T"-shaped,

asymmetric, etc.) dependent on the overall diaper design, and can comprise a

wide variety of liquid-absorbent materials commonly used in disposable

diapers such as, for example, comminuted wood pulp generally referred to as

airfelt. Examples of other suitable absorbent materials include creped

cellulose wadding; meltblown polymers, including coform; chemically

stiffened, modified or cross-linked cellulosic fibers; tissue, including tissue

wraps and tissue laminates; absorbent foams; absorbent sponges;

superabsorbent polymers; absorbent gelling materials; and any other known

absorbent material or combinations of materials. The configuration and construction of the absorbent element can be

varied (e.g., the absorbent element or other absorbent structure can have

varying caliper zones, a hydrophilic gradient, a superabsorbent gradient, or

lower average density and lower average basis weight acquisition zones; or

can comprise one or more layers or structures). However, the total absorbent

capacity of the absorbent element should be compatible with the design

loading and the intended use of diaper 21.

Exemplary absorbent structures for use as the absorbent element are

described in U.S. Patent 4,610,678 issued to Weisman et al. on September 9,

1986; U.S. Patent 4,673,402 issued to Weisman et al. on June 16, 1987; U.S.

Patent 4,834,735 issued to Alemany et al. on May 30, 1989; U.S. Patent

4,888,231 issued to Angstadt on December 19, 1989; U.S. Pat.. No. 5,137,537

issued to Herron et al. on August 11, 1992; U.S. Patent 5,147,345 issued to

Young et al. on September 15, 1992; U.S. Patent 5,342,338 issued to Roe on

August 30, 1994; U.S. Patent 5,260,345 issued to DesMarais et al. on

November 9, 1993; U.S. Patent 5,387,207 issued to Dyer et al. on February 7,

1995; and U.S. Patent 5,650,222 issued to DesMarais et al. on July 22, 1997.

Each of these patents is incorporated herein by reference.

The present invention is not dependent on the use of any particular

absorbent element. The foregoing are presented for purposes of illustration

and not limitation.

Backsheet 22 can be joined to topsheet 23, the absorbent element or

any other element of diaper 21 by any attachment means known in the art. For example, the attachment means can include a uniform continuous layer

of adhesive, a patterned layer of adhesive, or an array of separate lines,

spirals, or spots of adhesive. One preferred attachment means comprises an

open pattern network of filaments of adhesive as disclosed in U.S. Patent

4,573,986 issued to Minetola et al. on March 4, 1986. Other suitable

attachment means include several lines of adhesive filaments which are

swirled into a spiral pattern, as is illustrated by the apparatus and methods

shown in U.S. Patent 3,911,173 issued to Sprague, Jr. on October 7, 1975;

U.S. Patent 4,785,996 issued to Ziecker, et al. on November 22, 1978; and

U.S. Patent 4,842,666 issued to Werenicz on June 27, 1989. Each of the

foregoing patents is incorporated herein by reference. Adhesives which have

been found to be satisfactory are manufactured by H. B. Fuller Company of

St. Paul, Minnesota and marketed as HL-1620 and HL-1358-XZP.

Alternatively, the attachment means can comprise heat bonds, pressure

bonds, ultrasonic bonds, dynamic mechanical bonds, or any other suitable

attachment means or combinations of these attachment means as are known

in the art.

Fig. 2 illustrates one use of hook-and-loop fastening systems. This

particular use is a commercially important use of such systems and will be

used for convenience in this specification to illustrate the present invention.

It is to be understood that the present invention can be used in other

applications, and no such applications are disclaimed. The present invention is concerned with the loop structure portions of

hook-and-loop fastening systems. From even a cursory examination of Fig. 2,

those skilled in the art can readily deduce two requirements for loop

structures. First, loop structure 2 must be able to cooperate with hook

structure 3 to effectively releasably secure diaper 21 about the wearer.

Second, one skilled in the art would recognize that diaper 21 must be capable

of being made at high speed if it is to be commercially viable. This

recognition leads to the requirement that loop structure 2 must be such that

it can be affixed to diaper 21 in a high speed manufacturing process in a

condition such that it will function effectively in cooperating with hook

structure 3. The last words of the foregoing sentence are emphasized to

indicated that mere high speed application of loop element 2 to diaper 21,

while necessary, is not in and of itself sufficient. After application, loop

structure must be in condition for efficient, effective use.

Disposable diapers are made by well known processes (sometimes

called "converting processes") at high speed. The particular process used, of

course, depends on the design of the diaper and the materials used. In such

processes, various components (topsheet, backsheet, hook structure, loop

structure, etc.) are introduced into the process by being unwound from large

rolls of the material in question. (These large rolls are sometimes called

"parent rolls.") The converting processes operate at high speed so long as the

various materials can be unwound at high speed. Obviously, each parent roll

contains only a finite quantity of material. When the material on a parent roll is exhausted, the converting process must be either stopped completely

or significantly slowed while a new parent roll of material is installed and

the new supply of material is introduced into the converting process. In

order to provide converting processes with high average rates of production,

effort is expended in seeking ways to increase the amount of material on any

given parent roll.

One obvious way of increasing the amount of material on a parent roll

is to make larger parent rolls. That is to say, to make parent rolls having

larger diameters. There are practical limits to the diameter of a parent roll,

however. One such limit is the physical space available for a parent roll.

This space is dictated by the particular orientation of the converting process

and the process equipment involved.

A second limit is imposed on the diameter of a parent roll used for

compressible materials. This limit is imposed because as the diameter of a

parent roll increases, the pressure (or force per unit area) exerted on the

material increases as the distance from the center of the parent roll

decreases. Stated in another way: as material is wound onto a parent roll at

any given tension, compressive forces are exerted on the material already on

the roll. These forces are in general not uniform throughout the radius of the

parent roll, but are greater nearer the center of the roll than nearer the

surface of the roll. Winding more material onto the parent roll will, then,

increase the compressive forces, particularly near the center of the roll.

These increased compressive forces can represent a limitation on roll diameter when the material in question is deformed by the forces to such an

extent that it will no longer perform its intended function effectively and

efficiently in the article of manufacture.

Another obvious way to increase the amount of a compressible

material on a parent roll of any given diameter is to increase the tension

with which it is wound onto the roll, thereby compressing the material and

decreasing the diameter of the parent roll for any given quantity of material.

This method can suffer from the same limitation as expressed in the

immediately preceding paragraph: increased compressive forces in the

parent roll can deform the material to an unacceptable extent.

The present invention permits the preparation of parent rolls of loop

structure material, which parent rolls have greater diameters than

heretofore possible and which material can be wound onto the parent rolls at

greater tension than heretofore possible. The net result of the greater

diameters and higher tensions is the placement of greater quantities of loop

structure material on the parent rolls thereby allowing longer intervals of

uninterrupted converting process operation and, hence, faster overall

production of disposable diapers. The invention is not concerned with the

preparation of parent rolls which can be prepared by any means known to

those skilled in the art. The invention is concerned with the treatment of the

loop structure material as it is being introduced into the converting process.

The present invention is of a restoration process for the loop structure

material after it is unwound from its parent roll. As used in this specification, "restore" is a verb meaning to remove deformations at least

partially from the loop elements of a loop structure thereby returning the

elements at least partially, in a practical sense, to their original orientation,

and thereby enhancing their ability to cooperate with hook elements relative

to the fully deformed state of the loop elements.

Fig. 3 is a cross sectional view of loop structure 2 illustrated in Fig. 1.

As noted above, illustrated loop structure 2 and loop elements 4 are intended

to represent a wide variety of such structures and elements while not

illustrating any one structure or element with particularity. In Fig. 3, "h"

indicates the average undeformed height of loop elements 4 and "g" indicates

the average gap (i.e. the average spacing) between adjacent loop elements 4.

Loop structures are sometimes supplied by the manufacturer as a "pre-

glued" material. That is to say, the manufacturer of a loop structure will

sometimes apply an article attachment adhesive (such as contact adhesive or

hot melt adhesive) to loop structure attachment surface 6. The function of

the attachment adhesives is, as the name implies, to attach the loop

structure to the article being manufactured. In the present invention, loop

structure 2 is free of attachment adhesive on loop structure attachment

surface 6 until it loop elements 4 have been restored and loop structure 2

passes on into the converting process as described below.

Fig. 4 illustrates deformed loop structure 2'. Deformed loop structure

2' is loop structure 2 of Fig. 3 after loop elements 4 of Fig. 3 have been

subjected to deforming forces such as the compressive forces present in a parent roll. Reference numeral 4' indicates deformed loop elements. The

deformation of the loop elements is, in general, permanent after compression

and deformation in the parent roll. Such deformation is deleterious because

the deformed loops will not cooperate with the hook elements of the fastening

system as effectively or efficiently as will loop elements having their original

configuration.

The first step of the present invention is the deforming of at least one

loop element of a loop structure (such as loop structure 2 of Fig. 3) by

winding the loop structure upon it self to form a parent roll. Techniques of

such winding are well known to those skilled in the art. The actual

technique used is immaterial to the practice of the present invention. The

width of the parent roll is determined by the width of the loop structure

required by the converting process in which the loop structure will be used.

In the general case, the width of the parent roll will be the final length of the

loop structure (e.g. the landing zone) used on the article. The diameter of the

parent roll is dictated by the physical dimensions and orientation of the

converting equipment. The tension of the loop structure as it is wound into a

parent roll is dictated by the permitted diameter of the parent roll, the

desired quantity of loop structure to be incorporated into the parent roll, and

the extent of deformation of the loop elements that can be tolerated.

The second step of the present invention is the unwinding of the loop

structure with its deformed loop element (such as deformed loop structure 2'

of Fig. 4) from the parent roll. The third step of the present invention is restoring the deformed loop

elements by contacting them with a mechanical restoration device.

The fourth step of the present invention is using the restored loop

structure in a continuous converting process.

Fig. 5 is a schematic representation of the second, third, and fourth

steps of the present invention.

A parent roll 51 containing deformed loop structure 2' is placed by any

convenient technique on an unwind stand (not illustrated) well known to

those skilled in the art. In the second step of the present invention,

deformed loop structure 2' is unwound from parent roll 51 as parent roll 51

rotates in the direction indicated. Deformed loop elements 4' are oriented as

shown. (The size of deformed loop elements 4' relative to other items in Fig.

5 is exaggerated for purposes of illustration.) In the third step of the present

invention loop elements 4' are contacted with mechanical restoration device

52. During this contact, deformed loop elements 4' are restored to their

undeformed state as loop elements 4 and deformed loop structure 2' is

restored to loop structure 2. In the fourth step of the present invention, and

as indicated by arrow 55, loop structure 2 is introduced into converting

process 53.

Converting process 53 can be any convenient process in which loop

structures are used in the manufacture of articles such as disposable diapers.

For purposes of the present invention, the details of converting process 53

are immaterial. Fig. 5 suggests that mechanical restoration device 52 is in the form of

a roller rotating in the direction indicated. That is the preferred design and

the preferred rotation, but not the only design or only rotation for mechanical

restoration device 52. For example, the mechanical restoration device could

be in the form of a substantially flat plate over which deformed loop

structure 2' passes. (See Fig. 8 and Fig. 9 and the discussion below.)

Fig. 5 is a schematic representation. Various auxiliary mechanical

and electronic elements which facilitate the implementation of the process of

the present invention are not illustrated. For example, the unwind stand

mentioned above, various drive and support mechanisms for parent roll 51

and mechanical restoration device 52, guide rolls for loop structures 2 and 2',

various other supports, speed controls, and the like are neither illustrated

nor specified. Those skilled in the art can readily select these auxiliary

elements.

In a preferred embodiment of the present invention, mechanical

restoration device 52 is a rotating brush in the form of a cylinder as

illustrated in Fig. 6. Cylindrical rotating brush 62 has a diameter d and a

length L; it rotates about axis of rotation 61. The outer surface of brush 62 is

provided with a plurality of bristles 63. (Only a small portion of bristles 63

on the surface of brush 62 are illustrated.) Preferably, bristles 63 are round.

The length, diameter, and material of construction of bristles 63 are all

determined by the nature of the loop elements concerned. Preferably,

bristles 63 have a free length greater than about loop height h shown in Fig. 3. The free length of a bristle is the distance from the free tip of the bristle to the surface to which the bristle is attached. Preferably, the average

bristle free length is less than about 3h (i.e. less than about three times the

average undeformed height of loop elements 4 as shown in Fig. 3). The material of construction of the bristles can be readily selected so that

restoration and not tearing of the loop elements occurs. The bristles are

selected sot hat the average bristle will itself bend rather than tear a loop element. Preferably, bristles 63 have an average bending modulus of less than yield strength of the loop elements.

The spatial arrangement of bristles 63 on mechanical restoration 62 device is not critical so long as there are enough bristles present to adequately contact, during restoration, the deformed loop elements of the particular deformed loop structure in question. Length L and diameter d of

mechanical restoration device 63 are not critical to the practice of the present invention and can be convenient dimensions readily selected by those skilled in the art.

Alternatively, the mechanical restoration device of the present

invention can be a rotating cylinder as illustrated in Fig. 7. In this alternate

preferred embodiment of the present invention, mechanical restoration

device 52 is a rotating cylinder as illustrated in Fig. 7. Rotating cylinder 72

has a diameter "d" and a length "L;" it rotates about axis of rotation 71.

Cylinder 72 is provided with a scarfing surface 74. Scarfing surface 74 has a

roughness of at least about 500 RMS. Surface roughness is measured in accordance with American National

Standard ANSI/ASME B46.1-1985.

Length L, diameter d, and the material of construction of cylinder 72

are not critical to the practice of the present invention and can be convenient

dimensions and materials readily selected by those skilled in the art.

The two preferred mechanical restoration devices described above are

in the form of a rotating brush and a rotating cylinder. Alternatively, the

mechanical restoration device can be in the form of a substantially flat brush

or a substantially flat plate as shown in Fig. 8 and Fig. 9. For the purposes

of the present invention, a brush or a plate is substantially flat if the portion

in contact with the deformed loop elements is curved, but subtends an arc of

less than about 180°. The substantially flat brush and the substantially flat

plate can be stationary or can move with respect to the deformed loop

structure in contact with it.

In Fig. 8, mechanical restoration device 82 is illustrated as a

substantially flat brush provided with a plurality of bristles 83. Preferably,

bristles 83 have a length greater than about loop height h shown in Fig. 3.

Preferably, bristle length is less than about 3h. Preferably, bristles 83 have

a diameter less than about 2g (i.e. less than about twice the average gap

between loop elements 4 as shown in Fig. 3). The material of construction of

the bristles can be readily selected so that restoration and not tearing of the

loop elements occurs. Preferably, bristles 83 have a modulus of less than the

modulus of elasticity of the loop elements. The spatial arrangement of bristles 83 on mechanical restoration 82 device is not critical so long as there

are enough bristles present to adequately contact, during restoration, the

deformed loop elements of the particular deformed loop structure in question.

Length L, width w, and thickness t of mechanical restoration device 83 are

not critical to the practice of the present invention and can be convenient

dimensions readily selected by those skilled in the art. In use, mechanical

restoration device 83 is substituted for mechanical restoration device 52 as

illustrated in Fig. 5

In Fig. 9, mechanical restoration device 92 is illustrated as a

substantially flat plate with a scarfing surface 94. Scarfing surface 94 has a

roughness of at least about 500 RMS. Length L, width w, thickness t, and

the material of construction of mechanical restoration device 92 are not

critical to the practice of the present invention and can be convenient

dimensions and materials readily selected by those skilled in the art. In use,

mechanical restoration device 92 is substituted for mechanical restoration

device 52 as illustrated in Fig. 5

Examples

The following examples are presented by way of illustration and not

by way of limitation. Example One:

Loop structure material (hereinafter referred to as the "loop web")

denominated EBL (XPL-7034) and comprising polypropylene loop elements

affixed to a polyethylene loop support structure is obtained from The

Minnesota Mining and Manufacturing Company, Personal Care and Related

Products Division, of St. Paul, MN. The loop web has an original thickness

of about 0.381 mm, which includes a loop element height of about 0.30 mm.

This loop web, 178 mm wide, is wound upon itself to form a parent roll of

loop web material; the loop elements are oriented toward the center (i.e. axis)

of the parent roll. The parent roll has an initial finished diameter of about

81.3 cm. The loop web is wound upon itself at a tension of about 35.4 kg per

m of width of loop web. The loop elements of the loop web are deformed from

their original upright orientation to such an extent that the average

thickness of the loop web on the parent roll is about 380 microns.

The parent roll of loop web is placed into a loop restoration system

having the general orientation illustrated in Fig. 5. It is to be understood

that various support and drive elements, well known to those skilled in the

art, are not shown in Fig. 5. More specifically, the parent roll is placed in an

unwind stand where the loop web is unwound at a liner speed of about 24.7

m per min and directed toward a mechanical restoration device. In this

Example One, the mechanical restoration device comprises a rotating

cylindrical brush provided with a plurality of bristles. The overall diameter

of the cylindrical brush, from bristle tip to bristle tip, is about 7.6 cm and the cylindrical brush is about 200 mm long. The average bristle in the

cylindrical brush has an average free length of about 10 mm. The cylindrical

brush is mechanically driven so that its surface moves in the direction of the

moving loop web, and the surface of the cylindrical brush is driven at a linear

speed of abut 24.7 m per min. The loop web contacts the surface of the

cylindrical brush through an angle of about 20°. During the passage of the

loop web over the mechanical restoration device, the deformed loop elements

associated with the loop web are restored essentially to their original upright

orientation and are rendered suitable for use in the manufacture of

disposable diapers. After leaving the mechanical restoration device of this

Example One, the loop web, with its now-restored loop elements, is used in

the manufacture of disposable diapers according to the teaching of Buell in

the hereinbefore mentioned U.S. Patent 5,221,274.

Example Two

Example One is repeated except that the mechanical restoration

device comprises a cylinder, about 7.6 cm in diameter and 200 mm long,

provided with a scarfing surface. This surface has a roughness of about 500

and is provided by Plasma Coating of Tennessee, Inc. of Memphis, TN. This

surface is denominated 936 and comprises a polymer having Teflon ®

polytherthalatefluroethylene grit embedded therein. In this Example Two,

the cylinder (i.e. the mechanical restoration device) is mechanically driven so

that its surface moves counter to the direction of movement of the loop web

and at a speed of about 12 m per min. As in Example One, the deformed loop elements are restored essentially to their original upright orientation, and

the loop web, with its now-restored loop elements, is used in the manufacture

of disposable diapers according to the teaching of Buell in the hereinbefore

mentioned U.S. Patent 5,221,274.

Claims

What is claimed is:

1. In a continuous process for the manufacture of an article comprising a

hook-and-loop fastening system, the improvement comprising the steps of:

a.) Providing a loop structure comprising a plurality of loop

elements, said loop elements being affixed to a support substrate, said

support substrate being substantially free of article attachment adhesive;

b.) Deforming at least a portion of said loop elements by winding

said loop structure upon itself to form a parent roll;

c.) Unwinding said loop structure from said parent roll;

d.) Restoring at least a portion of said deformed loop elements by

contacting said deformed loop elements with a mechanical restoration device;

and

e.) Introducing said loop structure comprising said restored loop

elements into said continuous process.

2. The process of Claim 1 wherein said mechanical restoration device

comprises a brush.

3. The process of Claim 2 wherein said brush comprises a rotating cylinder.

4. The process of Claim 2 wherein said brush is a substantially flat brush.

5. The process of Claims 2, 3, or 4 wherein said brush comprises a plurality

of bristles, said bristles having an average free length greater than about

three times the average undeformed height of said loop elements.

6. The process of Claim 5 wherein said bristles have an average bending

modulus less than the average modulus of elasticity of said loop elements.

7. The process of Claim 1 wherein said mechanical restoration device

comprises a rotating cylinder provided with a scarfing surface.

8. The process of Claim 1 wherein said mechanical restoration device

comprises a substantially flat plate provided with a scarfing surface.

9. The process of Claims 7 or 8 wherein said scarfing surface has an average

roughness of at least about 500 RMS.

10. A disposable diaper comprising a hook-and-loop fastening system, said

diaper made by a continuous process, said process comprising the steps of:

a.) Providing a loop structure comprising a plurality of loop

elements, said loop elements being affixed to a support substrate, said

support substrate being substantially free of article attachment adhesive; b.) Deforming at least a portion of said loop elements by winding

said loop structure upon itself to form a parent roll;

c.) Unwinding said loop structure from said parent roll;

d.) Restoring at least a portion of said deformed loop elements by

contacting said deformed loop elements with a mechanical restoration device;

and

e.) Affixing said loop structure comprising said restored loop

elements to said disposable diaper.

11. The disposable diaper of Claim 10 wherein said mechanical restoration

device comprises a brush, said brush comprising a plurality of bristles, said

bristles having an average free length greater than about three times the

average undeformed height of said loop elements and an average bending

modulus less than the average modulus of elasticity of said loop elements.

12. The disposable diaper of Claim 10 wherein said mechanical restoration

device comprises a scarfing surface, said scarfing surface having an average

roughness of at least about 500 RMS.