U.S. patent application number 11/303074 was filed with the patent office on 2007-06-14 for bonding of elastomeric substrate under stretched conditions.
This patent application is currently assigned to Kimberly-Clark Worldwide, Inc.. Invention is credited to Lars N. Nordang.
Application Number | 20070131343 11/303074 |
Document ID | / |
Family ID | 37670713 |
Filed Date | 2007-06-14 |
United States Patent
Application |
20070131343 |
Kind Code |
A1 |
Nordang; Lars N. |
June 14, 2007 |
Bonding of elastomeric substrate under stretched conditions
Abstract
A method of bonding material in a process system for producing a
bonded product includes the steps of loading a plurality of rolls
of elastomeric material in an unwind system; programming a
controller with an unwind speed and a rewind speed, the controller
in communication with the unwind system and a rewinder disposed
downstream from the unwind system for respective communication of
the unwind and rewind speeds to the unwind system and the rewinder;
unwinding a quantity of material from the plurality of rolls of
elastomeric material into a pressure bonder disposed upstream of
the rewinder, the pressure bonder and the rewinder operating faster
than the unwind system operating at the unwind speed to generate a
speed differential, wherein the speed differential imparts a
stretch state to the quantity of material; and bonding the
stretched quantity of material with the pressure bonder.
Inventors: |
Nordang; Lars N.; (Neenah,
WI) |
Correspondence
Address: |
DORITY & MANNING, P.A.
POST OFFICE BOX 1449
GREENVILLE
SC
29602-1449
US
|
Assignee: |
Kimberly-Clark Worldwide,
Inc.
|
Family ID: |
37670713 |
Appl. No.: |
11/303074 |
Filed: |
December 14, 2005 |
Current U.S.
Class: |
156/229 ;
156/308.2; 156/324 |
Current CPC
Class: |
B32B 2307/51 20130101;
A61F 13/15593 20130101; B32B 38/1825 20130101; B32B 2038/0028
20130101; B32B 2309/14 20130101 |
Class at
Publication: |
156/229 ;
156/324; 156/308.2 |
International
Class: |
B32B 37/20 20060101
B32B037/20; B29C 65/00 20060101 B29C065/00; B32B 37/00 20060101
B32B037/00 |
Claims
1. A method of bonding material in a process system for producing a
bonded product, the method comprising the steps of: loading a
plurality of rolls of elastomeric material in an unwind system;
programming a controller with an unwind speed and a rewind speed,
the controller in communication with the unwind system and a
rewinder disposed downstream from the unwind system for respective
communication of the unwind and rewind speeds to the unwind system
and the rewinder; unwinding a quantity of material from the
plurality of rolls of elastomeric material into a pressure bonder
system disposed upstream of the rewinder, the pressure bonder
system and the rewinder operating faster than the unwind system
operating at the unwind speed to generate a speed differential,
wherein the speed differential imparts a stretched state to the
quantity of material; and bonding the stretched quantity of
material with a pressure bonder of the pressure bonder system.
2. The method of bonding material as in claim 1, wherein the
plurality of rolls of elastomeric material includes a high loft
elastomeric material.
3. The method of bonding material as in claim 1, wherein the
plurality of rolls of elastomeric material is selected from the
group comprising a stretch bonded laminate, a vertical filament
stretch bonded laminate, a continuous filament stretch bonded
laminate and combinations thereof.
4. The method of bonding material as in claim 1, wherein the
quantity of material is selected from the group consisting of
polyesters, polyolefins, and combinations thereof.
5. The method of bonding material as in claim 1, wherein the unwind
system includes at least one unwinder being configured to unwind at
least one of the plurality of rolls of elastomeric material.
6. The method of bonding material as in claim 1, wherein the
controller is a computer or a programmable logic controller.
7. The method of bonding material as in claim 1, wherein the rewind
speed is at least twice as fast as the unwind speed.
8. The method of bonding material as in claim 1, wherein the
pressure bonder includes a bonding roll and an anvil, the bonding
roll and the anvil being configured to exert a pressure to induce
internal heating in the quantity of material to fuse a plurality of
fibers of the quantity of material into a bond between the pattern
roll and the anvil.
9. The method of bonding material as in claim 1, wherein the
quantity of material is stretched from about 25% to about 200%
before bonding by the pressure bonder.
10. The method of bonding material as in claim 1, wherein the
quantity of material is stretched from about 50% to about 150%
before bonding by the pressure bonder.
11. The method of bonding material as in claim 1, wherein the
quantity of material is stretched in a machine direction,
transverse to the machine direction, or transverse to the machine
direction and in the machine direction before bonding by the
pressure bonder.
12. The method of bonding material as in claim 1, wherein the
bonding step imparts a bond to the quantity of material having a
bond strength greater than a material strength of the quantity of
material such that material failure of the quantity of material
occurs before failure of the bond.
13. The method of bonding material as in claim 1, further
comprising the step of nipping the quantity of material with a nip
to stretch the quantity of material before bonding by the pressure
bonder, the nip being disposed between the unwind system and the
rewinder.
14. A method of bonding material in a process system for producing
a bonded product, the method comprising the steps of: loading a
first roll of high loft elastomeric material in a first unwinder
and a second roll of high loft elastomeric material in a second
unwinder; programming a controller with an unwind speed and a
rewind speed, the controller in communication with the first and
second unwinders and a rewinder disposed downstream from the first
and second unwinders for respective communication of the unwind and
rewind speeds to the first and second unwinders and the rewinder;
unwinding a first quantity of material from the first roll and a
second quantity of material from the second roll into a nip
disposed upstream of a pressure bonder system, the pressure bonder
system and the rewinder operating faster than the first and second
unwinders and the nip to generate a speed differential, wherein the
speed differential imparts a stretched state to the first and
second quantities of material; and bonding the stretched first and
second quantities of material together with a pressure bonder of
the pressure bonder system.
15. The method of bonding material as in claim 14, wherein the
first and second quantities of material are selected from the group
consisting of a high loft elastomeric material, a stretch bonded
laminate, a vertical filament stretch bonded laminate, a continuous
filament stretch bonded laminate, a polyester, a polyolefin and
combinations thereof.
16. The method of bonding material as in claim 14, wherein the
controller is a computer or a programmable logic controller.
17. The method of bonding material as in claim 14, wherein the
rewind speed is at least twice as fast as the unwind speed.
18. The method of bonding material as in claim 14, wherein the
quantities of material are stretched from about 25% to about 200%
before bonding by the pressure bonder.
19. The method of bonding material as in claim 14, wherein the
bonding step imparts a bond to the quantities of material having a
bond strength greater than a material strength of the quantities of
material such that material failure of the quantities of material
occurs before failure of the bond.
20. A method of bonding material in a process system for producing
a bonded product, the method comprising the steps of: providing a
roll of elastomeric material; programming a controller with a first
speed and a second speed, the controller in communication with the
roll of elastomeric material and a bonder system disposed
downstream from the roll of elastomeric material for respective
communication of the first and second speeds to the roll of
elastomeric material and the bonder system; feeding a quantity of
material from the roll of elastomeric material at the first speed
into the bonder system, the bonder system operating at the second
speed faster than the first speed to generate a speed differential,
wherein the speed differential imparts a stretched state to the
quantity of material; and bonding the stretched quantity of
material with a bonder of the bonder system.
21. The method of bonding material as in claim 20, wherein the roll
of elastomeric material is a high loft elastomeric material.
22. The method of bonding material as in claim 20, wherein the
controller is a computer or a programmable logic controller.
23. The method of bonding material as in claim 20, wherein the
first speed is at least twice as fast as the second speed.
24. The method of bonding material as in claim 20, wherein the
bonder system includes a nip being configured to impart the
stretched state to the quantity of material.
Description
BACKGROUND OF THE INVENTION
[0001] Disposable garments, such as infant and children's diapers,
swimwear and training pants, as well as adult incontinence
garments, conventionally include materials that are joined together
and connected using a bonding process, or the materials are bonded
in related converting systems prior to bonding the materials
together. For example, a training pant or other pant-type garment
may have a front side panel and a back side panel that are bonded
together at a side seam to provide a complete side panel. The side
panels are typically connected at the side seam using an ultrasonic
process such as the process described by You et al. in U.S. Pat.
App. Pub. No. 2005/0133144 A1.
[0002] The ability to form strong ultrasonic bonds using
conventional processes is limited by several factors, including the
process converting speeds or production line speeds, bonding time
or dwell time, and the thickness and/or basis weight of the
materials being bonded. Moreover, in the case of rotary ultrasonic
or pressure bonding of high loft substrates, bonding pattern roll
pins have a tendency of piercing the elastomeric material instead
of creating a suitable bond.
[0003] A bonding process that provides sufficient bond strength for
high loft substrates and does not decrease production line speeds
is needed in the industry.
SUMMARY OF THE INVENTION
[0004] The present invention is generally directed to a method of
bonding high loft substrates efficiently by placing the high loft
substrate in a stretched condition in preparation for bonding.
According to an aspect of the invention, this can be readily
achieved by feeding in less substrate to the process than an amount
of substrate being extracted from the process. Generally, a lower
loft substrate results, which is more suitable for bonding. The
component parts of the bonding system are simple, reliable and
economical to manufacture and use. Other advantages of the
invention will be apparent from the following description and the
attached drawings or can be learned through practice of the
invention.
[0005] In one aspect of the invention, a method of bonding material
in a process system for producing a bonded product includes the
steps of loading a plurality of rolls of elastomeric material in an
unwind system; programming a controller with an unwind speed and a
rewind speed, the controller in communication with the unwind
system and a rewinder disposed downstream from the unwind system
for respective communication of the unwind and rewind speeds to the
unwind system and the rewinder; unwinding a quantity of material
from the plurality of rolls of elastomeric material into a pressure
bonder system disposed upstream of the rewinder, the pressure
bonder system and the rewinder operating faster than the unwind
system operating at the unwind speed to generate a speed
differential, wherein the speed differential imparts a stretched
state to the quantity of material; and bonding the stretched
quantity of material with a pressure bonder of the pressure bonder
system. The plurality of rolls of elastomeric material can include
a high loft elastomeric material. The plurality of rolls of
elastomeric material can also include a stretch bonded laminate, a
vertical filament stretch bonded laminate, a continuous filament
stretch bonded laminate or combinations of these laminates.
Further, the quantity of material can be polyesters, polyolefins
and combinations thereof.
[0006] Also in this aspect of the invention, the unwind system can
have an unwinder for unwinding at least one of the rolls of
elastomeric material. Further in this aspect, the controller can be
a computer or a programmable logic controller to program the rewind
speed at least twice as fast as the unwind speed. In one example,
the unwind speed is from about 600 feet per minute to about 1200
feet per minute, although the unwind speed can be orders of
magnitude slower or faster with the rewind speed being at least
somewhat faster than the unwind speed.
[0007] Further in this aspect of the invention, the pressure bonder
can have a pattern roll and an anvil for exerting a pressure to
bond the quantity of material with a pattern between the pattern
roll and the anvil. For example, the pressure can be a lineal
pressure of about 0.05*10.sup.6 N/m up to about 6*10.sup.6 N/m.
[0008] Alternatively, or additionally, the pressure bonder in this
aspect of the invention can include a bonding roll and an anvil,
which exert a pressure such as the pressure noted above to induce
internal heating in the quantity of material to fuse a plurality of
fibers of the quantity of material into a bond between the pattern
roll and the anvil.
[0009] Still further in this aspect of the invention, the method of
bonding material can include at least two rolls providing
respective first and second quantities of material. The first and
second quantities of material can be stretched equally before
bonding by the pressure bonder. Also, one or more of the quantities
of material can stretched from about 25% to about 200% before
bonding by the pressure bonder, more particularly, from about 50%
to about 150% before bonding by the pressure bonder. The quantities
of material can be stretched in a machine direction or transverse
to the machine direction before bonding by the pressure bonder, or
the quantities of material can be stretched transverse to the
machine direction and in the machine direction before bonding by
the pressure bonder. In these aspects of the invention, the bonding
step imparts a bond to the quantity of material having a bond
strength greater than a material strength of the quantity of
material such that material failure of the quantity of material
occurs before failure of the bond.
[0010] Also in this aspect of the invention, the plurality of rolls
of elastomeric material can be a single roll and the quantity of
material can be folded at least once to generate at least two
layers of material, the at least two layers of material being
equally stretched before bonding by the pressure bonder.
[0011] Further in this aspect of the invention, the quantity of
material can be nipped with a nip to stretch the quantity of
material before bonding by the pressure bonder, the nip being
disposed between the unwind system and the rewinder and operating
at the unwind speed.
[0012] In another aspect of the invention, a method of bonding
material in a process system for producing a bonded product
includes the steps of loading a first roll of high loft elastomeric
material in a first unwinder and a second roll of high loft
elastomeric material in a second unwinder; programming a controller
with an unwind speed and a rewind speed, the controller in
communication with the first and second unwinders and a rewinder
disposed downstream from the first and second unwinders for
respective communication of the unwind and rewind speeds to the
first and second unwinders and the rewinder; unwinding a first
quantity of material from the first roll and a second quantity of
material from the second roll into a nip disposed upstream of a
pressure bonder system, the pressure bonder system and the rewinder
operating faster than the first and second unwinders and the nip to
generate a speed differential, wherein the speed differential
imparts a stretched state to the first and second quantities of
material; and bonding the stretched first and second quantities of
material together with a pressure bonder of the pressure bonder
system. In this aspect, the first and second quantities of material
can be a high loft elastomeric material, a stretch bonded laminate,
a vertical filament stretch bonded laminate, a continuous filament
stretch bonded laminate, a polyester, a polyolefin and combinations
of these.
[0013] Also in this aspect of the invention, the controller can be
a computer or a programmable logic controller to control the rewind
speed at least twice as fast as the unwind speed.
[0014] Further in this aspect, the pressure bonder includes a
pattern roll and an anvil, the pattern roll and the anvil being
configured to exert a pressure to bond the first and second
quantities of material with a pattern between the pattern roll and
the anvil. Alternatively or additionally, the pressure bonder
includes a bonding roll and an anvil, the bonding roll and the
anvil being configured to exert a pressure to induce internal
heating in the first and second quantities of material to fuse a
plurality of fibers of the first and second quantities of material
into a bond between the pattern roll and the anvil. The quantities
of material are stretched from about 25% to about 200% before
bonding by the pressure bonder, more particularly, from about 50%
to about 150% before bonding by the pressure bonder. The quantities
of material can be stretched in a machine direction before bonding
by the pressure bonder, or the quantities of material can be
stretched transverse to a machine direction before bonding by the
pressure bonder. Alternatively, the quantities of material can be
stretched transverse to the machine direction and in the machine
direction before bonding by the pressure bonder. In this aspect,
the bonding step imparts a bond to the quantities of material
having a bond strength greater than a material strength of the
quantities of material such that material failure of the quantities
of material occurs before failure of the bond. Also in this aspect,
at least one of the quantities of material can be folded at least
once to generate at least two layers, the at least two layers being
equally stretched before bonding by the pressure bonder.
[0015] In yet another aspect of the invention, a method of bonding
material in a process system for producing a bonded product
includes the steps of providing a roll of elastomeric material;
programming a controller with a first speed and a second speed, the
controller in communication with the roll of elastomeric material
and a bonder system disposed downstream from the roll of
elastomeric material for respective communication of the first and
second speeds to the roll of elastomeric material and the bonder
system; feeding a quantity of material from the roll of elastomeric
material at the first speed into the bonder system, the bonder
system operating at the second speed faster than the first speed to
generate a speed differential, wherein the speed differential
imparts a stretched state to the quantity of material; and bonding
the stretched quantity of material with a bonder of the bonder
system. In this aspect, the roll of elastomeric material is a high
loft elastomeric material. Also in this aspect of the invention,
the controller can be a computer or a programmable logic controller
for controlling the first and second speeds; for example, to set
the first speed at least twice as fast as the second speed
[0016] Other features and aspects of the invention are discussed in
greater detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] A full and enabling disclosure of the present invention,
including the best mode thereof to one skilled in the art, is set
forth more particularly in the remainder of the specification,
including reference to the accompanying figures, in which:
[0018] FIG. 1 is a schematic elevational view of one embodiment of
a system and process for producing bonded substrates in accordance
with an aspect of the present invention;
[0019] FIG. 2 is a detailed elevational view of a section of the
system as in FIG. 1;
[0020] FIG. 3 is a perspective view of a section of the system as
in FIG. 1 particularly showing stretched webs of material being
bonded according to one aspect of the invention; and
[0021] FIG. 4 is a magnified view of surfaces of the stretched webs
as in FIG. 3.
[0022] Repeat use of reference characters in the present
specification and drawings is intended to represent the same or
analogous features or elements of the present invention.
DEFINITIONS
[0023] Within the context of the present description, the following
terms may have the following meanings: [0024] "Machine direction"
(MD) refers to the length of a fabric or material in the direction
in which it is produced or converted, as opposed to "cross
direction" or "cross-machine direction" (CD or CMD), which refers
to the width of a fabric in a direction generally perpendicular to
the machine direction. [0025] "Attached" and "joined" refers to the
bonding, adhering, connecting, and any other method for attaching
or joining two elements. Two elements will be considered to be
attached or joined together when they are bonded directly to one
another or indirectly to one another, such as when each is directly
attached to an intermediate element. [0026] "Sheet" refers to a
layer, which may be a film, a foram, or a nonwoven web. [0027]
"Member" when used in the singular can refer to a single element or
a plurality of elements. [0028] The term "composite nonwoven
fabric", "composite nonwoven", "laminate", or "nonwoven laminate",
as used herein, unless otherwise defined, refers to a material
having at least one elastic material joined to at least one sheet
material. In most embodiments such laminates or composite fabric
will have a gatherable layer, which is bonded to an elastic layer
or material so that the gatherable layer may be gathered between
bonding locations. As set forth herein, the composite elastic
laminate may be stretched to the extent that the gatherable
material gathered between the bond locations allows the elastic
material to elongate. This type of composite elastic laminate is
disclosed, for example, in U.S. Pat. No. 4,720,415 to Vander Wielen
et al., which is incorporated herein in its entirety by reference
thereto.
[0029] As used herein, the term "nonwoven web" refers to a web
having a structure of individual fibers or threads that are
interlaid, but not in an identifiable, repeating manner. Nonwoven
webs have been, in the past, formed by a variety of processes such
as, for example, meltblowing processes, spunbonding processes and
bonded carded web processes.
[0030] The term "continuous filaments", as used herein, refers to
strands of continuously formed polymeric filaments. Such filaments
will typically be formed by extruding molten material through a die
head having a certain type and arrangement of capillary holes
therein.
[0031] As used herein, the term "meltblown fibers" means fibers
formed by extruding a molten thermoplastic material through a
plurality of fine, usually circular, die capillaries as molten
thermoplastic material or filaments into a high velocity gas (e.g.
air) stream which attenuates the filaments of molten thermoplastic
material to reduce their diameter, which may be to microfiber
diameter. Thereafter, the meltblown fibers are carried by the high
velocity gas stream and are deposited on a collecting surface to
form a web of randomly disbursed meltblown fibers. Such a process
is disclosed, for example, U.S. Pat. No. 3,849,241 to Butin, which
is incorporated herein in its entirety by reference thereto.
[0032] As used herein, the term "spunbonded fibers" refers to small
diameter fibers formed by extruding a molten thermoplastic material
as filaments from a plurality of fine, usually circular,
capillaries of a spinerette with the diameter of the extruded
filaments then being rapidly reduced as by, for example, eductive
stretching or other well-known spun-bonding mechanisms. The
production of spun-bonded nonwoven webs is illustrated in patents
such as, for example, U.S. Pat. Nos. 4,340,563 to Appel et al., and
3,692,618 to Dorschner et al. The disclosures of these patents are
incorporated herein in their entireties by reference thereto.
[0033] "Extendable" or "extensible" means that property of a
material or composite by virtue of which it stretches or extends in
the direction of an applied biasing force by at least about 25% of
its relaxed length. An extendable material does not necessarily
have recovery properties. For example, an elastomeric material is
an extendable material having recovery properties. A meltblown web
may be extendable, but not have recovery properties and, thus, be
an extensible but non-elastic material.
[0034] "Elastomeric," "elastic," and "elasticized" refer to a
material or composite which can be stretched or elongated by at
least 25% of its relaxed length and which will recover, upon
release of the applied force, at least 10% of its elongation. It is
generally preferred that the elastomeric material or composite be
capable of being elongated by at least 100%, more preferably by at
least 300%, of its relaxed length and recover at least 50% of its
elongation.
[0035] "Non-extensible" refers to a material that does not stretch
or extend by at least about 25% of its relaxed length without
fracture upon application of a biasing force. Materials that are
extensible or elastomeric are not considered "non-extensible."
[0036] "Untensioned" as used herein to describe a material web does
not mean lacking all tension. In order to handle and process moving
webs, some moderate amount of tension is needed to hold the web or
material in place. An "untensioned" web or material, as used
herein, is under enough tension to process the material, but less
than that required to cause substantial deformation of the
material.
[0037] "Necked material" refers to any material, which has been
constricted in at least one dimension by processes such as, for
example, drawing.
[0038] "Neck-bonded" laminate refers to a composite material having
an elastic member that is bonded to a member while the member is
extended in the machine direction creating a necked material that
is elastic in the cross-direction. Examples of neck-bonded
laminates are disclosed in U.S. Pat. Nos. 4,965,122; 4,981,747;
5,226,992; and 5,336,545, which are incorporated herein by
reference in their entirety for all purposes.
[0039] "Reversibly-necked material" refers to a necked material
that has been treated while necked to impart memory to the material
so that when force is applied to extend the material to it
pre-necked dimensions, the necked and treated portions will
generally recover to their necked dimensions upon termination of
the force. A reversibly-necked material may include more than one
layer. For example, multiple layers of spunbonded web, multiple
layers of meltblown web, multiple layers of bonded carded web or
any other suitable combination of mixtures thereof. The production
of reversibly-necked materials is described in U.S. Pat. Nos.
4,965,122 and 4,981,747, incorporated herein by reference for all
purposes.
[0040] "Stretch-bonded" laminate refers to a composite material
having at least two layers in which one layer is a gatherable layer
and the other layer is an elastic layer. The layers are joined
together when the elastic layer is in an extended condition so that
upon relaxing the layers, the gatherable layer is gathered. For
example, one elastic member can be bonded to another member while
the elastic member is extended at least about 25% of its relaxed
length. Such a multilayer composite elastic material may be
stretched until the non-extensible layer is fully extended.
Examples of stretch-bonded laminates are disclosed, for example, in
U.S. Pat. Nos. 4,789,699, 4781,966, 4,720,415, 4,657,802, and
4,655,760, which are incorporated herein by reference in their
entirety for all purposes.
[0041] "Neck stretch-bonded" laminate refers a laminate made from
the combination of a neck-bonded laminate and a stretch-bonded
laminate. Examples of necked stretch bonded laminates are disclosed
in U.S. Pat. Nos. 5,114,781 and 5,116,662, which are incorporated
herein in their entirety by reference thereto for all purposes. A
necked stretch bonded laminate can be stretchable in both the
machine and cross-machine directions.
[0042] Various aspects and embodiments of the invention will be
described in the context of a material for disposable absorbent
articles, such as disposable diapers, children's training pants,
incontinence articles, feminine care products, diaper pants,
disposable swim pants and the like. It should be appreciated that
this is for illustrative purposes only, and that the invention is
not limited to any particular absorbent article or absorbent
articles in general. The material according to the invention may
have beneficial uses in any number of applications, such as
protective medical clothing, drapes, gowns and the like.
[0043] It is to be understood by one of ordinary skill in the art
that the present discussion is a description of exemplary
embodiments only, and is not intended as limiting the broader
aspects of the present invention.
DETAILED DESCRIPTION
[0044] The present disclosure is generally directed to a method for
producing a bonded substrate. More particularly, the present
disclosure is directed to stretching a high loft substrate to
facilitate bonding of the substrate with a folded section of that
substrate, with one or more other substrates, during converting
processes or a combination of these. Through the above processes, a
lower loft substrate results, which is more suitable for
bonding.
[0045] Referring now to FIGS. 1-3, an exemplary system and process
for producing bonded substrates in accordance with certain aspects
of the present invention are illustrated. As shown most clearly in
FIG. 1, a process system is designated in general by the element
number 10 and broadly includes a plurality of rolls of elastomeric
material 12A, 12B, which are unwound by respective unwinds 14A, 14B
in an unwind system 14. Respective webs of material 24A, 24B from
the rolls of elastomeric material 12A, 12B are nipped together by a
nip 16. In this example, the nip 16 operates at a generally slower
speed than a pressure bonder system including a pressure bonder 18
located downstream from the nip 16. A speed differential is created
by this arrangement, which imparts a stretched state to the webs of
material 24A, 24B prior to bonding as will be described in greater
detail below. The skilled artisan will instantly appreciate that
although multiple rolls of material 12A, 12B are shown by way of
example in FIG. 1, a single web of material from a single roll of
material can be stretched, converted and bonded according to the
invention. Likewise, more than two rolls of material can be
stretched for conversion and bonding processes. For instance, the
present invention can be used to bond one or more webs of material
in various converting processes as described, for example, in U.S.
Pat. No. 6,740,200 to Seymour et al., which is incorporated herein
by reference thereto. Accordingly, it should be understood that the
invention is not limited to the exemplary process system 10 shown
in the accompanying figures. It will be further appreciated that
although the nip 16 is shown in a vertical roll-roll arrangement,
the nip 16 can be an S-wrap arrangement or other suitable
arrangement as known in the art.
[0046] As shown in FIGS. 1-3, the webs of material 24A, 24B are
high loft substrates according to an aspect of the invention that
are bonded efficiently when the webs of material 24A, 24B are in a
stretched state prior to being bonded by the pressure bonder 18.
The stretched state is readily achieved by feeding in less of the
webs of material 24A, 24B to the process (e.g., into the nip 16)
than what is being taken up by the pressure bonder 18. The result
is a lower loft substrate that is more suitable for bonding and
producing, for instance, an elastomeric composite 36 as shown or
for bonding the webs of material 24A, 24B during converting
processes, which is further described below.
[0047] As shown more particularly in FIG. 1, the unwind system 14
and its unwinds 14A, 14B are used to unwind the rolls of
elastomeric material 12A, 12B as briefly introduced above. In this
example, the rolls of elastomeric material 12 A, 12 B are disposed
in the respective unwinds 14A, 14B on respective spindles 26A, 26B.
As shown, the webs of material 24A, 24B are fed together by a
plurality of a carrier rollers 28 into the nip 16. The nip 16 in
this example is a roll 30A and an opposing roll 30B that are spaced
apart at a desired, adjustable distance to create a predetermined
nip pressure for nipping the webs of material 24A, 24B together
prior to entry into the pressure bonder 18. The rolls 30A, 30B
apply pressure to the webs of elastomeric material 24A, 24B at a
fairly high surface pressure, which can be between about 20 and 300
pounds per linear inch ("PLI"). These and other pressures are
described in greater detail below.
[0048] More particularly, the nip 16 in FIG. 1 performs the primary
stretching of the webs of material 24A, 24B. The speed ratio of the
nip 16 relative to the pressure bonder 18 in this example can be
varied and in most cases is between about 2:1 and 8:1 and in some
cases approximately 4:1 to 6:1. By way of example and not of
limitation, the nip 16 and its rolls 30A, 30B can operate from
about 600 feet per minute ("FPM") to about 1200 FPM. Accordingly,
the pressure bonder 18 in this example can operate from about 1200
FPM to about 2400 FPM. It will be appreciated that the speed of the
nip 16 can be slower or much faster than the foregoing examples,
and the speed can increased downstream at the pressure bonder 18 or
elsewhere in the process system 10 in order to impart stretch or
elongation to the webs of material 24A, 24B prior to bonding. The
skilled artisan will further appreciate that although the
nip/S-wrap 16 is shown upstream of the bonder 18 in this example, a
similar nip/S-wrap device can be located downstream to control the
web to achieve the desired amount of material stretch. In other
words, the pressure bonder system, including a plurality of nips,
create the stretch, but the pressure bonder 18 itself does not pull
the web through the process. Thus, the arrangement shown in FIG. 1
and the exemplary speeds above are provided merely for illustrative
purposes and do not limit the invention to these examples.
[0049] With more particular reference to the pressure bonder 18
shown in FIGS. 1-3, the pressure bonder 18 can be a calendaring
station such as a calendaring pattern roll 32 and a corresponding
or opposing anvil roll 34 (also referred to herein as a bottom or
backing roll or roller). As schematically shown, the anvil roll 34
can be fixed onto a base frame and the top roller or pattern roll
32 can be configured to ride on the anvil roll 34. As
representatively shown in FIG. 2, a forcing mechanism can be a
pneumatic air pressure cylinder configured at the ends of a shaft
of the pattern roll 32 to symmetrically exert a desired force F
(also referred to herein as a total force, a lineal-pressure value
or a loading force) for urging the pattern roll 32 toward the anvil
roll 34. Alternatively, the spatial positions of the pattern roll
32 and the anvil roll 34 can be exchanged or otherwise re-arranged,
and the anvil roll 34 can be fixed to the base and positioned above
the pattern roll 32. Still further, the pattern roll 32 can be
offset along a machine direction MD toward either side of the anvil
roll 34. The air pressure cylinders can then be installed to
operatively exert a loading force F that pushes or otherwise urges
the pattern roll 32 upwards and/or sideways against the anvil roll
34.
[0050] In the nip region between the pattern roll 32 and the anvil
roll 34, the invention can be configured to provide a distinctive
lineal-pressure value F, which has the units of force per lineal
distance, and may also be referred to as the nip force value. The
lineal-pressure value can be determined by the formula:
F=Q.sub.T/L; [0051] where: Q.sub.T=the total force which is exerted
by the forcing mechanism to urge the pattern roll 32 toward contact
with the anvil roll 34; [0052] L=an average length of contact
between the peripheral bonding surfaces of the bonding elements and
the surface of the anvil roll 34 if the pattern roll 32 contacted
the anvil roll 34 as measured along an axial cross direction of the
anvil roll 34.
[0053] The average length of contact, L, can be determined by the
following formula: L=n*G/S [0054] where: n=the number of pin lines;
G=bonding surface area of an individual bonding element (e.g.,
bonding surface area of an individual bonding pin); S=the MD pin
spacing distance.
[0055] For circular pins; G=(.pi.*d.sup.2)/4. Accordingly, for the
circular pins: L=(n* .pi.*d.sup.2)/ (4* S) [0056] where: d=the pin
diameter and .pi.=3.14.
[0057] In particular aspects, the lineal pressure value can be at
least a minimum of about 0.05*10.sup.6 N/m. The lineal pressure
value can alternatively be at least about 0.05*10.sup.6 N/m and can
optionally be at least about 1*10.sup.6 N/m to provide desired
benefits. In other aspects, the lineal pressure value can be up to
a maximum of about 10*10.sup.6 N/m or more. The lineal pressure
value can alternatively be up to about 6.times.10.sup.6N/M and can
optionally be up to about 4.5*10.sup.6 N/m to provide desired
effectiveness. Further details of pressure bonding methods as
described by example above can be found in U.S. patent application
Ser. No. 11/138,099, which is incorporated herein by reference.
[0058] With further reference now to FIG. 3, the pattern roll 32
and the anvil roll 34 are pressed together in an exemplary fashion
to bond one or more of the webs of material 24A, 24B as described
above. In this example, the pattern roll 32 includes a plurality of
bonding protrusions or pins 33 to impart a pattern in the machine
direction MD onto the bonded elastomeric composite 36. The skilled
artisan will instantly appreciate that the pattern roll 32 and the
anvil roll 34 can be arranged other than in the machine direction
MD to impart bonding patterns to the elastomeric composite 36.
Additionally, other sets of pattern rolls and anvil rolls can be
provided having different machine direction and cross machine
direction orientations as well as different pins other than the
protrusions 33 as shown. Moreover, according to an aspect of the
invention, pins are not required to bond the webs of material 24A,
24B since the invention may simply rely on the web materials 24A,
24B deforming plastically under the nip force of the rolls 32, 34.
Bonding will therefore occur due to plastic deformation induced
internal heating and fusion or melting of the materials 24A, 24B.
As known, larger deformation rates imply faster internal heating
and increasing bonding speed increases the deformation rate. Also,
the smaller a roll diameter the larger the deformation rate.
Further, it is known that heat conduction diminishes the
effectiveness of a bonding process; therefore, the rolls 32, 34 and
any pins 33 are selected from materials, which will not conduct
heat efficiently from the webs 24A, 24B.
[0059] Turning now to FIG. 4, a section of the elastomeric
composite 36 is shown, which includes a plurality of fibers 37. As
shown, a first bond side or pattern roll side 38A of the bonds 38
includes at least some of the fibers 37 that have been melt bonded
together. An opposing or bond anvil side 38B of the first bond side
38A is also shown, which most clearly shows compression of the
fibers 37 by the bonding force F described above.
[0060] The fibers 37 shown in FIG. 4 are an array of filaments that
may number from about 200 separate strands to as much as 2600
separate strands. A greater or lesser number of strands, however,
are also possible. Additionally, various types of compositions and
various processing conditions may be used to form the elastic
continuous filaments that form the fibers 37. For example, a
Kraton.RTM. brand elastic polymer may be fed into an extruder where
the polymer is melted at a controlled temperature of between about
260.degree. F. and 460.degree. F., and in certain instances at
about 385.degree. F. In other embodiments, depending on the
particular polymer employed, the melt temperature may be
approximately 470.degree. F. to 480.degree. F. The polymer is then
extruded through a predetermined number of apertures in a die head
in a generally downward direction into separate continuous
filaments at a pressure of approximately 300 to 4000 psi (typically
from about 1500 to about 2000 psi). One particular class of
polymers that may be used in the present process is the Kraton.RTM.
G series of polymers distributed by Shell Chemical Company (now
available from Kraton Products US-LLC). Various Kraton.RTM.
polymers may be utilized. However, the skilled artisan will
recognize that the invention is not limited to this or any
particular polymer or material from which to form the continuous
filaments. For example, various materials, including the following,
may be used: polypropylene, polyethylene, polyesters, polyethylene
terephthalate, polybutane, polymethyldentene, ethylene propylene
co-polymers, polamides, tetrablock polymers, styrenic block
copolymers, polyhexamethylene adipamide, poly-(oc-caproamide),
polyhexamethylenesebacamide, polyvinyls, polystyrene,
polyurethanes, thermoplastic polymers, polytrifluorochloroethylene,
ethylene vinyl acetate polymers, polyetheresters, polyurethane,
polyurethane elastomerics, polyamide elastomerics, polyamides,
viscoelastic hot melt pressure sensitive adhesives, cotton, rayon,
hemp and nylon.
[0061] Other exemplary elastomeric materials that may be used
include polyurethane elastomeric materials such as those available
under the trademark ESTANE from B. F. Goodrich & Co., polyamide
elastomeric materials such as those available under the trademark
PEBAX from the Rilsan Company, and polyester elastomeric materials
such as those available under trade designation HYTREL from E. I.
DuPont De Nemours & Company. However, the invention is not
limited to only such elastomeric materials. For example, various
latent elastic materials such as the Arnitel-brand polymers may be
utilized to provide the necessary elasticity characteristics to the
continuous filaments.
[0062] Likewise, the above-referenced materials, and others, may be
utilized in forming the outer facings of the presently described
laminate. In particular, various webs may be utilized that are
formed from elastomeric or nonelastomeric fibers. Various polyester
elastic materials are, for example, disclosed in U.S. Pat. No
4,741,949 to Morman et al., which is incorporated herein in its
entirety by reference thereto. Other useful elastomeric polymers
also include, for example, elastic copolymers of ethylene and at
least one vinyl monomer such as, for example, vinyl acetates,
unsaturated aliphatic monocarboxylic acids, and esters of such
monocarboxylic acids. The elastic copolymers and formation of
elastomeric fibers from these elastic copolymers are disclosed in,
for example, U.S. Pat. No. 4,803,117, which is also incorporated
herein in its entirety by reference thereto.
[0063] With brief reference once more to FIG. 1, a controller,
computer or programmable logic controller 40 is connected to
various components of the process system 10 to control the
components. For example, the controller 40 can be electronically
connected to the unwinds 14A, 14B, the nip 16, the pressure bonder
18, the rewinder 20 and combinations of these and other components
of the process system 10 to control the unwind and rewind speeds as
well as the nip pressures described above. More specifically, the
controller 40 can be programmed with a software program 42 for
setting and controlling desired speeds and pressures and to adjust
the speeds and pressures of the components to accommodate different
types of substrates being processed by the process system 10.
[0064] The present invention may be better understood with respect
to the following tests and examples.
Testing Procedures
[0065] The following tests were performed on the samples that were
produced. See, eg., the elastomeric composite 36 and the bonds 38
described above.
[0066] Porosity was measured using STM (scientific, technical and
medical) procedure number 3801. Porosity was measured using a
Frazier air permeability tester. The units are cubic feet per
minute per square foot (cfm per ft.sup.2) units.
[0067] Elongation was measured using test procedure number STM
529-W. Elongation may be tested using any suitable tensile testing
equipment, such as those available from the Syntech Corporation of
Cary, N.C., or from the Instron Corporation of Canton, Mass.
[0068] In a Peel Test, a laminate is tested for the amount of force
needed to pull the layers of the laminate apart. The peel strength
was measured using testing procedure number STM 751-W. The samples
were tested in the cross machine direction. Any suitable tensile
testing equipment may be used in order to perform the
procedure.
EXAMPLE
[0069] The following example was performed in order to determine
the effect of stretching webs of material, such as webs 24A, 24B
discussed herein, prior to bonding using a bonder such as the
bonder 18 as shown in FIG. 1. At least one of the webs of material
24A, 24B was unwound into the nip 16, specifically between the
rolls 30A, 30B and stretched prior to the pressure bonder 18 and
the rewinder 20. The pressure bonder 18 and the rewinder 20 were
processing at a line speed approximately twice that of the unwind
system 14 and the nip 16. Stated another way, the pressure bonder
18 and the rewinder 20 took away the material 24A, 24B at a speed
twice that of the nip 16 prior to the pressure bonder 18, which
ensured that the material 24A, 24B was in a stretched state at the
bonder 18. Thirty samples were produced and tested. As shown in the
following charts, various product speeds per minute--assuming a
product pitch of 29 inches based on the trial pressure bonder--were
employed for this test in combination with various pressures of the
pattern roll 32 and the anvil roll 34. TABLE-US-00001 Cylinder
Pressure Speed P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 ppm fpm (psig) (psig)
(psig) (psig) (psig) (psig) (psig) (psig) (psig) (psig) 250 604 10
15 20 25 30 35 40 45 50 55 350 846 10 15 20 25 30 35 40 45 50 55
450 1088 10 15 20 25 30 35 40 45 50 55
Manual checks of bond strength of the bonded materials 24A, 24B
revealed material failure generally before bond failure.
[0070] These and other modifications and variations to the present
invention may be practiced by those of ordinary skill in the art,
without departing from the scope and spirit of the present
invention, which is more particularly set forth in the appended
claims. In addition, it should be understood that aspects of the
various embodiments might be interchanged either in whole or in
part. Furthermore, those of ordinary skill in the art will
appreciate that the foregoing description is by way of example only
and is not intended to limit the invention so further described in
such appended claims.
* * * * *