Note: Descriptions are shown in the official language in which they were submitted.
~zxx~~
ABSORBENT 'PR011UC'L' FL1I3 PERSOINA~ USB
BACKGROUND OF THE INVENTION
1. Field of the Invention.
This invention relates to the field of absorbent products,
especially for use by persons with incontinence. Specifically,
the invention is concerned with diapers or underpants type
products, as well as absorbent pads and the like, which are
~.0 highly absorptive due to the inclusion of a super absorbent
polymer in an embossed target a~.~ea.
2. Description of the Prior Art
There has been a great deal. of recent development in the
field of personal absorbent products ranging from diapers for
infants to adult briefs for people with urinary incontinence.
One major area of development has been broadly in the field of
super absorbent polymers, such as starches, acrylics modified
cellulose, gums and the like. In some respects, th'e super
absorbent polymers are far superior to cellulose fluff and
other conventional absorbent media used in personal absorbent
products. For example, the polymers, on a weight basis, have
an absorption capacity which is far greater than fluff. In
addition, super absorbent polymers retain absorbed liquid, even
under pressure, far better than fluff which is subject to
"squeeze-out" where absorbed liquid is released from fluff when
it is subjected to pressure.
There are some drawbacks, however, to super absorbent
polymers as components of personal absorbent products.
Generally, super absorbent polymers are inferior to fluff in
terms of rate of absorption of liquid. Another drawback of
super absorbent polymers is their susceptibility to what is
referred to as "gel--blocking'' where a layer containing super
absorbent polymer is wetted, the polymer absorbs the liquid and
the gelled polymer, which has expanded to many times its dry
size, blocks additional liquid from entering the layer. Super
absorbent polymers, because they are finely powdered, present
manufacturing difficulties in terms of satisfactorily
incorporating into absorbent products.
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Super absorbent polymers have been incorporated into
absorbent products in a variety of ways. In some cases, super
absorbent polymer is sprinkled into a fluff layer or deposited
between two fluff layers, as disclosed in US Patent No.
4,381,782, but these approaches are plagued by problems arising
from the migration of the powder from the place it is deposited.
Another approach entails the use of tissue with super absorbent
polymer powder fixed to it. Such tissue, also known as
laminate, has been used in absorbent products alone and in
combination with conventional fluff.
Examples of the use of laminate alone are shown in US
Patent No. 4,568,341. This patent discloses a special laminate
structure including undulations and small hinge and flap members
formed in the laminate. This laminate structure compensates for
the relatively slow absorbency rate of the super absorbent
polymer in the laminate.
Composite absorbent products including one or more
layers of laminate and one or more layers of fluff are disclosed
in US Patent Nos. 3,888,256, 4,333,465, 4,411,660, 4,592,751,
4,622,036, 4,643,726 and 4,699,619.
US Patent No. 4,055,180 discloses an absorbent article
including super absorbent polymer powder disposed in pockets
formed in an absorbent pad.
A product distributed under the trademark Slimline
comprises a backing sheet, a facing sheet, a layer of laminate
adjacent to the facing sheet and a layer of fluff between the
laminate and the backing sheet.
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Summary of the Invention
The instant invention is based upon the discovery of
an improved absorbent article incorporating an improved
absorbent insert or core. According to one embodiment of the
invention, the insert comprises a fluff layer physically
integrated to at least one layer of laminate. The insert is
positioned in the absorbent article so that the laminate will be
adjacent to a wearer. In a preferred embodiment, the fluff
layer and the laminate are embossed between rollers that
physically integrate the two layers and produce transfer sites
through which liquid
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is rapidly transferred into the fluff layer, away from a wearer.
In another embodiment, an absorbent insert is produced
by embossing a laminate between a smooth roller and a patterned
roller and trimming and folding the embossed laminate. The
insert is folded to produce an insert with a central region with
an exposed pattern of embossed depressions and, on each side of
the central region, lateral regions with an exposed, smooth
surface .
In yet another embodiment, an absorbent insert is
produced by depositing super absorbent polymer powder on a
portion of a layer of fluff, covering the powder with at least
one tissue layer, and embossing the assembly to produce an
integrated absorbent insert with transfer sites through which
liquid is rapidly transferred into the fluff layer, away from a
wearer.
According to another embodiment, an absorbent insert
is produced by depositing super absorbent polymer powder on a
portion of layer of fluff, covering at least a portion of the
fluff with polymer deposited thereon with at least one laminate
layer, and embossing the assembly to produce an integrated
absorbent insert with transfer sites through which liquid is
rapidly transferred into the fluff layer for absorption by the
polymer powder dispersed in the fluff.
More specifically, the present invention provides an
absorbent core including a given amount of a super
absorbent polymer, said core consisting essentially of a water
permeable cover sheet, an absorbent fluff layer having first
and second major surfaces, said first surface being positioned
adjacent to said cover sheet, an absorbent laminate layer for
absorbing and retaining liquid, said absorbent laminate layer
~
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(a) being positioned between said fluff layer and said cover
sheet, (b) consisting essentially of aperture free tissue and a
first portion of super absorbent polymer that is subject to gel
blocking when wet, and is present in an amount sufficiently
great that gel blocking occurs when the laminate is wet, said
first portion of super absorbent polymer being less than the
given amount, and being secured to and supported on said
tissue, and (c) being positioned so that it is adjacent to and
covers at least a central portion of the first major surface of
said fluff layer, a second portion of super absorbent polymer
distributed in said fluff layer, adjacent to the first major
surface thereof wherein said fluff layer and said absorbent
laminate layer are connected to each other by a plurality of
channel regions consisting of compressed, physically integrated
portions of said fluff layer and of said absorbent laminate
layer, the channel regions having a given density and, between
the channel regions discrete regions composed of portions of
said fluff layer and of said absorbent laminate layer, and
having a density less than the given density, said channel
regions having been formed by pressing absorbent laminate into
a moistened surface of said fluff layer, and the absorbent core
has improved absorbency as a consequence of said channel
regions, and is operable to absorb, through said cover sheet,
multiple wettings with simulated urine in quantities which
would cause gel blocking in the absence of said channel
regions.
The present invention also provides an absorbent
product consisting essentially of an absorbent core including a
given amount of a super absorbent polymer, said core consisting
essentially of a water permeable cover sheet, an absorbent
fluff layer having first and second major surfaces, said first
~
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surface being positioned adjacent to said cover sheet, an
absorbent laminate layer for absorbing and retaining liquid,
said absorbent laminate layer (a) being positioned between said
fluff layer and said cover sheet, (b) consisting essentially of
aperture free tissue and a first portion of super absorbent
polymer that is subject to gel blocking when wet, and is
present in an amount sufficiently great that gel blocking
occurs when the laminate is wet, said first portion of super
absorbent polymer being less than the given amount, and being
secured to and supported on said tissue, and (c) being
positioned so that it is adjacent to and covers at least a
central portion of the first major surface of said fluff layer,
a second portion of super absorbent polymer distributed in said
fluff layer, adjacent to the first major surface thereof,
wherein said fluff layer and said absorbent laminate layer
are connected to each other by a plurality of channel regions
consisting of compressed, physically integrated portions of
said fluff layer and of said absorbent laminate layer, the
channel regions having a given density and, between the channel
regions, discrete regions composed of portions of said fluff
layer and of said absorbent laminate layer, and having a
density less than the given density, said channel regions
having been formed by pressing absorbent laminate into a
moistened surface of said fluff layer, and the absorbent core
has improved absorbency as a consequence of said channel
regions, and is operable to absorb, through said cover sheet,
multiple wettings with simulated urine in quantities which
would cause gel blocking in the absence of said channel
regions, and a water impervious backing sheet positioned
adjacent the second surface of said absorbent fluff layer.
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The present invention also provides an absorbent core
including a super absorbent polymer, said core consisting
essentially of a water permeable cover sheet, an absorbent
fluff layer having first and second major surfaces, the first
surface being positioned adjacent to said cover sheet, a layer
of tissue disposed between the first major surface of said
fluff layer and said cover sheet, and super absorbent polymer
powder distributed in said fluff layer, adjacent to the first
major surface, wherein said fluff and tissue layers are
connected to each other by a plurality of channel regions
consisting of compressed, physically integrated portions of the
fluff and tissue layers having a given density and, between the
channel regions, discrete regions of portions of said fluff and
tissue layers having a density less than the given density,
said channel regions having been formed by pressing the tissue
layer into a moistened surface of the fluff layer, and the
absorbent core has improved absorbency as a consequence of said
channel regions, and is operable to absorb, through said cover
sheet, multiple wettings with simulated urine in quantities
which would cause gel blocking in the absence of said channel
regions.
The present invention also provides an absorbent
product consisting of essentially of an absorbent core
including a super absorbent polymer, said core consisting
essentially of a water permeable cover sheet, an absorbent
fluff layer having first and second major surfaces, the first
surface being positioned adjacent to said cover sheet, a layer
of tissue disposed between the first major surface of said
fluff layer and said cover sheet, and super absorbent polymer
powder distributed in said fluff layer, adjacent to the first
major surface, wherein said fluff and tissue layers are
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connected to each other by a plurality of channel regions
consisting of compressed, physically integrated portions of the
fluff and tissue layers having a given a given density and,
between the channel regions, discrete regions of portions of
said fluff and tissue layers having a density less than the
given density, said channel regions having been formed by
pressing the tissue layer into a moistened surface of the fluff
layer, and the absorbent core has improved absorbency as a
consequence of said channel regions, and is operable to absorb,
through said cover sheet, multiple wettings with simulated
urine in quantities which would cause gel blocking in the
absence of said channel regions, and a water impervious backing
sheet positioned adjacent the second surface of said absorbent
fluff layer.
The present invention also provides an absorbent core
consisting essentially of a water permeable cover sheet, an
absorbent fluff layer having first and second major surfaces,
said first surface being positioned adjacent to said cover
sheet, an absorbent laminate layer for absorbing and retaining
liquid, said absorbent laminate layer (a) being positioned
between said fluff layer and said cover sheet, (b) consisting
essentially of aperture free tissue and a super absorbent
polymer that is subject to gel blocking when wet, and is
present in an amount sufficiently great that gel blocking
occurs when the laminate is wet, said super absorbent polymer
being secured to and supported on said tissue, and (c) being
positioned so that it is adjacent to and covers at least a
central portion of said first major surface of said fluff
layer, wherein said first layer and said absorbent laminate
layer are connected to each other by a plurality of channel
regions consisting of compressed, physically integrated
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portions of said fluff layer and of said absorbent laminate
layer, the channel regions having a given density and, between
the channel regions, discrete regions composed of portions of
said fluff layer and of said absorbent laminate layer having a
density less than the given density, said channel regions
having been formed by pressing absorbent laminate into a
moistened surface of the fluff layer, and the absorbent core
has improved absorbency as a consequence of said channel
regions, and is operable to absorb, through said cover sheet,
multiple wettings with simulated urine in quantities which
would cause gel blocking in the absence of said channel
regions.
The present invention also provides an absorbent
product consisting essentially of an absorbent core consisting
essentially of a water permeable sheet, an absorbent fluff
layer having first and second major surfaces, said first
surface being positioned adjacent to said cover sheet, an
absorbent laminate layer for absorbing and retaining liquid,
said absorbent laminate layer (a) being positioned between said
fluff layer and said cover sheet, (b) consisting essentially of
aperture free tissue and a super absorbent polymer that is
subject to gel blocking when wet, and is present in an amount
sufficiently great that gel blocking occurs when the laminate
is wet, said super absorbent polymer being secured to and
supported on said tissue, and (c) being positioned so that it
is adjacent to and covers at least a central portion of said
first major surface of said fluff layer, wherein said fluff
layer and said absorbent laminate layer are connected to each
other by a plurality of channel regions consisting of
compressed, physically integrated portions of said fluff layer
and of said absorbent laminate layer, the channel regions
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having a given density and, between the channel regions,
discrete regions composed of portions of said fluff layer and
of said absorbent laminate layer having a density less than the
given density, said channel regions having been formed by
pressing absorbent laminate into a moistened surface of the
fluff layer, and the absorbent core has improved absorbency as
a consequence of said channel regions, and is operable to
absorb, through said cover sheet, multiple wettings with
simulated urine in quantities which would cause gel blocking in
the absence of said channel regions, and a water impervious
backing sheet positioned adjacent the second surface of said
absorbent fluff layer.
The present invention also provides an absorbent core
including a super absorbent polymer, said core consisting
essentially of a water permeable cover sheet, an absorbent
fluff layer having first and second major surfaces, the first
surface being positioned adjacent to said cover sheet, a layer
of tissue disposed between the first major surface of said
fluff layer and said cover sheet, and super absorbent polymer
powder distributed in said fluff layer, adjacent to the first
major surface, wherein said fluff and tissue layers are
connected to each other by a plurality of channel regions
consisting of compressed, physically integrated portions of the
fluff and tissue layers having a given density and, between the
channel regions, discrete regions of portions of said fluff and
tissue layers having a density less than the given density,
said channel regions having been formed by pressing the tissue
layer into a surface of the fluff layer to which an adhesive
has been applied, and the absorbent core has improved
absorbency as a consequence of said channel regions, and is
operable to absorb, through said cover sheet, multiple wettings
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with simulated urine in quantities which would cause gel
blocking in the absence of said channel regions.
The present invention also provides an absorbent product
consisting essentially of an absorbent core including a super
absorbent polymer, said core consisting essentially of a water
permeable cover sheet, an absorbent fluff layer having first
and second major surfaces, the first surface being positioned
adjacent to said cover sheet, a layer of tissue disposed
between the first major surface of said fluff layer and said
cover sheet, and super absorbent polymer powder distributed in
said fluff layer, adjacent to the first major surface, wherein
said fluff and tissue layers are connected to each other by a
plurality of channel regions consisting of compressed,
physically integrated portions of the fluff and tissue layers
having a given density and, between the channel regions,
discrete regions or portions of said fluff and tissue layers
having a density less than the given density, said channel
regions having been formed by pressing the tissue layer into a
surface of the fluff layer to which an adhesive has been
applied, and the absorbent core has improved absorbency as a
consequence of said channel regions, and is operable to absorb,
through said cover sheet, multiple wettings with simulated
urine in quantities which would cause gel blocking in the
absence of said channel regions, and a water impervious backing
sheet positioned adjacent the second surface of said absorbent
fluff layer.
The present invention also provides a method for
producing an absorbent core including a given amount of a super
absorbent polymer, the method comprising the steps of: (a)
providing an absorbent fluff layer having first and second
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major surfaces the first major surface being moistened; (b)
providing a water permeable cover sheet adjacent the first
major surface of the absorbent fluff layer; (c) providing an
absorbent laminate layer for absorbing and retaining liquid,
between the fluff layer and the cover sheet; the absorbent
laminate layer consisting essentially of aperture free tissue
and a first portion of super absorbent polymer that is subject
to gel blocking when wet, and is present in an amount
sufficiently great that gel blocking occurs when the laminate
is wet, said first portion of super absorbent polymer being
less that the given amount, and being secured to and supported
on said tissue; and being positioned so that it is adjacent to
and covers at least a central portion of the first major
surface of said fluff layer, a second portion of super
absorbent polymer distributed in said fluff layer, adjacent to
the first major surface thereof wherein said fluff layer and
said absorbent laminate layer are connected to each other by a
plurality of channel regions consisting of compressed,
physically integrated portions of said fluff layer and of said
absorbent laminate layer, the channel regions having a given
density and, between the channel regions discrete regions
composed of portions of said fluff layer and of said absorbent
laminate layer, and having a density less than the given
density, said channel regions having been formed by pressing
absorbent laminate into a moistened surface of said fluff
layer, and the absorbent core has improved absorbency as a
consequence of said channel regions, and is operable to absorb,
through said cover sheet, multiple wettings with simulated
urine in quantities which would cause gel blocking in the
absence of said channel regions (d) pressing the absorbent
laminate layer to the moistened surface of the fluff layer in a
manner that produces a plurality of channel regions consisting
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of compressed physically integrated portions of the fluff layer
and of the absorbent laminate layer, the channel regions having
a given density and, between the channel regions, discrete
regions composed of portions of the fluff layer and of the
absorbent laminate layer and having a density less than the
given density; the absorbent core having improved absorbency as
a consequence of the channel regions and being operable to
absorb, through the cover sheet, multiple wettings with
simulated urine in quantities which would cause gel blocking in
the absence of the channel regions.
The present invention also provides a method for
producing an absorbent core including a super absorbent
polymer, the method comprising the steps of: (a) providing an
absorbent fluff layer having first and second major surfaces,
the first major surface being moistened; (b) providing a water
permeable cover sheet adjacent the first major surface of the
fluff layer; (c) providing a layer of tissue between the first
major surface of the fluff layer and the cover sheet; (d)
distributing super absorbent polymer powder in the fluff layer,
adjacent the first major surface; (e) pressing the tissue layer
into the moistened surface of the fluff layer in a manner that
produces a plurality of channel regions consisting of
compressed, physically integrated portions of the fluff and
tissue layers having a given density and, between the channel
regions, discrete regions of portions of the fluff and tissue
layers having a density less than the given density; the
absorbent core having improved absorbency as a consequence of
the channel regions and being operable to absorb, through the
cover sheet, multiple wettings with simulated urine in
quantities which would cause gel blocking in the absence of the
channel regions.
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The present invention also provides a method for
producing an absorbent core, the method comprising the steps
of: (a) providing an absorbent fluff layer having first and
second major surfaces, the first major surface being moistened;
(b) providing a water permeable cover sheet adjacent the first
major surface of the absorbent fluff layer; (c) providing an
absorbent laminate layer, for absorbing and retaining liquid,
between the fluff layer and the cover sheet; the absorbent
laminate layer consisting essentially of aperture free tissue
and a super absorbent polymer that is subject to gel blocking
when wet, and is present in an amount sufficiently great that
gel blocking occurs when the laminate is wet, said super
absorbent polymer being secured to and supported on said
tissue, and being positioned so that it is adjacent to and
covers at least a central portion of said first major surface
of said fluff layer, wherein said first layer and said
absorbent laminate layer are connected to each other by a
plurality of channel regions consisting of compressed,
physically integrated portions of said fluff layer and of said
absorbent laminate layer, the channel regions having a given
density and, between the channel regions, discrete regions
composed of portions of said fluff layer and of said absorbent
laminate layer having a density less than the given density,
said channel regions having been formed by pressing absorbent
laminate into a moistened surface of the fluff layer, and the
absorbent core has improved absorbency as a consequence of said
channel regions, and is operable to absorb, through said cover
sheet, multiple wettings with simulated urine in quantities
which would cause gel blocking in the absence of said channel
regions; and (d) pressing the absorbent laminate layer into the
moistened surface of the fluff layer in a manner that produces
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a plurality of channel regions consisting of compressed,
physically integrated portions of the fluff layer and of the
absorbent laminate layer, the channel regions having a given
density and, between the channel regions, discrete regions
composed of portions of the fluff layer and of the absorbent
laminate layer having a density less than the given density;
the absorbent core having improved absorbency as a consequence
of the channel regions and being operable to absorb, through
the cover sheet, multiple wettings with simulated urine in
quantities which would cause gel blocking in the absence of the
channel regions.
The present invention also provides a method for
producing an absorbent core including a super absorbent
polymer, the method comprising the steps of: (a) providing an
absorbent fluff layer having first and second major surfaces an
adhesive being applied to the first major surface; (b)
providing a water permeable cover sheet adjacent the first
major surface of the fluff layer; (c) providing a layer of
tissue between the first major surface of the fluff layer and
the cover sheet; (d) distributing super absorbent polymer
powder in the fluff layer, adjacent the first major surface;
(e) pressing the tissue layer into the adhesive and the first
major surface of the fluff layer in a manner that produces a
plurality of channel regions consisting of compressed,
physically integrated portions of the fluff and tissue layers
having a given density and, between the channel regions,
discrete regions of portions of the fluff and tissue layers
having a density less than the given density; the absorbent
core having improved absorbency as a consequence of the channel
regions and being operable to absorb, through the cover sheet,
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31
multiple wettings with simulated urine in quantities which
would cause gel blocking in the absence of the channel regions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded, perspective view of the
absorptive components of one embodiment of an absorbent product
according to the present invention.
FIG. 2 is an exploded, perspective view of the
absorptive components illustrated in FIG. 1, and upper and
lower tissue layers.
FIG. 3 is a perspective view of an absorbent core
comprising the components illustrated in FIG. 2, after they
have been integrated by an embossing operation.
FIG. 4 is a perspective view of the absorbent core
during a trimming operation.
FIG. 5 is an exploded, perspective view of the
components of one embodiment of an absorbent product
incorporating the absorbent core illustrated in FIG. 4.
4
FTG. 6 is a perspective view of a completed absorbent
product according to one embodiment of t:he present invention.
FIG. 7 is an exploded perspective view of the absorptive
camponents of a second embodiment of an absorbent product
according to the present invention.
FIG. 8 is a perspective view of the absorptive components
illustrated in FIG. 7 after they have been joined together by
an embossing operation.
FIG. 9 is a perspective view of a tissue wrapping
operation applied to the embossed components illustrated in
FIG. 8.
FIG. 10 is a perspective view of 'the embossed components
after a cutting and folding operation.
FIG. 11 is an exploded, perspective view of a second
embodiment of an absorptive product incorporating the tissue
wrapped, embossed absorptive components illustrated in FIG. 10.
FIG. 12 is a perspective view of apparatus for depositing
polymer to praduce one of the absorptive components of third
and fourth embodiments of an absorbent product according to the
present invention.
FIG. 13 is a perspective view of absorbent components of
a third embodiment of the invention, including a component
produced on the apparatus illustrated in FIG. 12.
FIG. 14 is an exploded, perspective view of the absorptive
components illustrated in FIG. 13, and upper and lower tissue
layers.
FIG. 15 is a perspective view of an absorbent core
comprising the components illustrated in FIG. 14, after they
have been integrated by an embossing operation.
FIG. is is a perspective view of the absorbent core during
a trimming operation.
FIG. 17 is a perspective view of absorbent components of
a fourth embodiment of the invention, including a component
produced on the apparatus illustrated in FIG. 12.
FIG. 18 is an exploded, perspective view of the absorptive
components illustrated in FIG. 17, and upper and lower tissue
layers.
5
FIG. 19 is a perspective view c>f an absorbent core
comprising the components illustrated in FIG. 18, after they
have been iwtegrated by an embossing operation.
FIG. 20 is a perspective view of the absorbent core during
a trimming operation.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, absorptive components of one
embodiment of an absorptive product are indicated generally at
ZO 20. One of the absorptive components 20 is a relatively thick,
fluff layer of moisture absorbing material 22, such as
cellulose fluff, fluffed wood pulp, batting or the like. The
other one of 'the absorptive components 20 is a layer of
laminate 24 comprising tissue with particles of a super
absorbent polymer deposited thereon and secured thereto. A
preferred material for the laminate layer 24 is a laminate
containing a super absorbent polymer of the modified acrylic
type. Such a laminate is available from Gelok International
under the trademark "Gelok s000 double ply/double ply (1080)".
The laminate layer 24 is superposed on a central target
area 26 of the fluff layer 22, as indicated by dotted lines in
FIG. 1. The laminate layer 24 does not extend the full length
or width of the fluff layer 22, although a larger laminate
layer may be used. The laminate layer 24 has an extremely high
absorption capacity but the laminate itself is relatively
expensive. Accordingly, the laminate layer is advantageously
restricted to the target area 26 which coincides with the area
where urine voided by a wearer will first contact the
absorptive product. In the target area 26, the need for
absorptive capacity is the greatest and the laminate layer 24
meets this need.
Before the laminate layer 24 is deposited on the fluff
layer 22, water is sprayed on the central region 2f of the
fluff layer 22. The moisture serves to adhere the laminate
layer 24 to the fluff layer 22 during subsequent assembly
operations. The amount of water to be sprayed is not critical,
but there should be enough water to provide some modicum of
adhesion between the layers 22 and 24. On the other hand, the
s~ ~.~ r~s ~ r~'.~.
6
amount of water should be only enough to moisten 'the upper
surface of the fluff layer 22.
After water has been sprayed on the fluff layer 22, the
laminate layer 24 is deposited on the fluff layer 22 in the
target area 26, as shown in FTC. 2. An upper layer of tissue
28 is positioned on top of the layers 22 and 24 while a lower
layer of tissue 30 is positioned below the layer 22. After the
tissue layers 28 and 30 are b~°ought into contact with the
absorbent core 20, the components are subjected to an embossing
step. A smooth roller (not shown) is applied to the lower
tissue layer 30 and a patterned roller (not shown) is applied
to the opposed, upper tissue la!,~er 28 to produce an embossed
absorbent core 32. A suitable diamond embossing pattern is
shown in FIG. 3, reflected in the pattern shown on the surface
Z5 of the tissue layer 30. The embossing pattern on the embossing
die (not shown) applied to the upper tissue layer 28 produces
a pattern of channels 34 in the surface of the tissue layer 28,
in the laminate layer 24, and in the fluff layer 22. As is
explained below, these channels 34 constitute transfer sites
through which liquid is absorbed quickly from above the upper
tissue layer 28, through the laminate layer 24, to the fluff
layer where it will be absorbed. The channels 34 are
interconnected in a continuous network which promotes excellent
wicking characteristics.
In the channels 34, there is a high density interface
between the tissue layer 28, the laminate layer 24 and the
fluff layer 22. In this interface, there is a physical bond
between the layers 28, 24 and 22 which gives the absorbent core
32 physical integrity. In the areas between the channels 34,
the layers 28, 24 and 22 have a lower density than these layers
have in the channels 34.
The embossing step can be carried out advantageously with
approximately 50 to 175 lbs of pressure per lineal inch of the
embossing rollers. A variety of patterns would be suitable for
the patterned embossing roller, beside the one reflected in the
upper tissue layer 28 shown in FIG. 3. Particulars about the
embossing pattern are discussed below in connection with some
examples of the invention.
~~~~~~r~..
7
The embossing operation was carried out with and without
the step of spraying water on the fluff layer. In the cases
whexe no water was sprayed, the embossing step did not result
in a physical bond between the fluff layer and the laminate
layer. Rather, the laminate layer and the fluff layer remained
discreet layers, like the layeres in the prior art Slimline
product. However, when the embossing operation was carried out
after water had been sprayed on the fluff layer, a physical
bond was produced between the f:~uff layer and the laminate
layer.
It will be appreciated that the manufacturing steps
described above with reference to FIGS. 1-3 can be applied to
bulk materials supplied, for example, from rolls.
Specifically, the fluff layer 22, the laminate layer 24 and the
tissue layers 28 and 30 can be manufactured into an embossed,
absorbent care 32 of infinite length which can later be cut to
appropriate length and incorporated into an absorbent product
according to the instant invention. After the absorbent core
32 has been embossed, it is preferably subjected to a de-
bulking operation in which it is passed between two compression
rollers (not shown). This step adds further integrity to the
embossed absorbent core 32 and promotes more economical
packaging by producing thinner absorbent products.
Referring now to FIG. 4, the embossed absorbent core 32
is illustrated after ears 36 have been trimmed therefrom to
produce an absorbent insert 38, with leg cut outs 40, for
incorporation in an absorbent product. The cut outs 40 extend
inwardly toward, but terminate just short of, the laminate
layer 24. The ears 36 can be recycled, if desired, to yield
material suitable for producing additional fluff layers 22.
The trimming can be carried out with a die-cutter which may
include a cutter for cutting the embossed absorbent core 32 to
produce an absorbent insert 38 of a given length.
Alternatively, a separate cutter may be used to cut absorbent
core material to an appropriate length.
With reference to FIG. 5, a water impervious bac%ing sheet
42 is illustrated below the absorbent insert 38. A plurality
of lines 44 c>f a hot melt type adhesive are applied
longitudinally to the backing sheet 42, across the entire width
thereof. In the illustrated embodiment, elastic means 46 are
sectared to 'the banking sheet 42 in spaced, parallel
relationship to one another. Preferably, the elastic means 46
comprise a plurality of individual elastic threads secured to
the backing sheet 42 by an adhesive which is applied thereto
and to the backing sheet 42. Then, a center portion 48 of the
elastic means 46 is stretched, and the stretched elastic means
46 are applied to the adhesive on the backing sheet 42. When
the adhesive sets and the stretching is relaxed, gathers 58
(FIG. 6) are formed by the center portion 48 of the elastic
means 46.
Also shown in FIG. 5 is a facing sheet 50 which has the
same length and width as 'the backing sheet. The facing sheet
50 is composed of a non~woven material through which liquid
will readily pass for absorption in the absorbent insert 38.
Several sprays 52 of hot melt adhesive are applied
longitudinally to the facing sheet 50, over a central portion
having a width corresponding generally with the width of the
absorbent insert 38. With the lines 44 and sprays 52 of hot
2o melt in place, the components shown in FIG. 5 are assembled by
positioning the absorbent insert 38 centrally on the backing
sheet 42 and positioning the facing sheet 50 thereon. After
assembly, these components are passed between compression
rollers (not shown) to promote good bonding therebetween.
With reference to FIG. 6, an absorbent product 54 is
illustrated after leg cut outs 56 have been trimmed therefrom.
Gathers 58 are formed, adjacent to a central portion of the leg
cut outs 56, by the central portion 48 (FIG. 5) of the elastic
means 46. The gathers 58 serve to prevent leakage by promoting
a snug fit of the absorbent product 54 around the legs of a
wearer. Adhesive tab fasteners 60 are secured to a rear panel
62 of the absorbent product 54 in a known fashion. The tab
fasteners 60 include an adhesive side 64 which remains secured
to a release paper 66, until the absorbent product 54 is to be
worn. With the absorbent product 54 positioned on a wearer,
the tab fasteners 60 are lifted from the release paper 66 and
the adhesive side 64 is applied to the outside of the backing
sheet 42 on a front panel 68 of the absorbent product 54,
thereby securing the absorbent product 54 to the wearer.
Preferably, the adhesive on the side 64 of the tab fasteners
is one which can be released from and refastened to the backing
sheet ~2, so that the tab fasteners 60 are refastenable.
E7~AMPLE 1
An absorbent core corresponding with the core 32 was
produced from cellulose .fluff and Gelok 6000 double ply/double
ply (1080) laminate. The super absorbent polymer in the
laminate was a polyacrylate product which is distributed by
Chemdal under the trade name Aridall 1080. The core was
embossed with a 1 inch by 1 inch diamond pattern on an upper
surface thereof. The channels had a width of approximately ~;
inch. Approximately 45~ of the :surface area of the core was
constituted by channels and the remaining 555 of the surface
area of the core was not channelled.
CONTROLS A, D, C, D, E~ F' AND Ci
For purposes of comparison, but not in accordance with the
instant invention, several absorbent cores were produced, as
described below.
Absorbent core A consisted of embossed cellulose fluff
having the same base weight as the cellulose fluff used in
Example 1. Core A was embossed with the same diamond pattern
as the core of Example 1.
Absorbent core B comprised unembossed cellulose fluff
having the same base weight as the fluff used in producing
Example 1.
Absorbent core C comprised a layer of the Gelok 6000
double ply/double ply (1080] laminate on top of a cellulose
fluff layer. This core differed from Example 1 only in that
it was not embossed. This sore corresponds with the core of
a product that is distributed under the trademark Slimline.
Absorbent core n comprised a layer of embossed cellulose
fluff on top of which Aridall 1080 polyacrylate super absorbent
polymer had been sprinkled. The amount of super absorbent
polymer was controlled to provide the same weight thereof, per
square inch of the cellulose fluff, as the weight of super
absorbent polymer in the Gelok 6000 double ply/double ply
(1080' laminate, per square inch thereof.
'~'~~ ~~ ~w ~~
Absorbent core E comprised a layer of unembossed cellulose
fluff on top of which Aridall 1080 polyacrylate super absorbent
polymer had been sprinkled. The amount of super absorbent
polymer was controlled to provide the same weight thereof, per
5 square inch of the cellulose fluff, as the weight of super
absorbent polymer in the Gelok 6000 double ply/double ply
{1080) laminate, per square inch thereof.
Absorbent core F correspands with Example 1 except for the
embossing pattern. Rather than ithe diamond shaped embossing
10 pattern, absorbent core F was embossed between smooth upper and
lower embossing rollers.
Absorbent core G comprises cellulose fluff which has been
split into two layers, between which Aridall 1080 polyacrylate
super absorbent polymer had been sprinkled. The amount of
super absorbent polymer was controlled 'to provide the same
weight thereof, per square inch of the cellulose fluff, as the
weight of super absorbent polymer in the Gelok 6000 double
ply/double ply (1080) laminate, per square inch thereof.
The absorbent insert of Example 1 and the absorbent cores
A-G were tested for absorbency {rate), wicking and skin
wetness. The procedure for each test is described below. The
results of each 'test are sat forth in Table I.
ABSORBENCY
In this test, a four inch by four inch square sample of
absorbent core material, with a water impervious backing, is
placed on a level surface. A test plate with a plurality of
evenly spaced apertures is placed on the sample. The test
plate has sides to retain a test liquid until it passes through
the apertures to the absorbent core. The test liquid is a 1.00
NaCl solution. A timer is started after 10.0 milliliters of
the test liquid has been introduced into the test plate. The
timer is stopped when the test liquid has emptied from the test
plate, through the apertures and into the absorbent core. The
results of this kind of test are indicative of the rate at
which an absorbent product will absorb urine. For example, an
absorbent core with a 2 second time in this absorbency test
will absorb urine at a faster rate than an absorbent core with
a 5 second time in 'this absorbency test.
s~.d~~~~~~~.
:11
STCIN WETNESS
In this test, a three inch by five inch rectangular sample
of absorbent core, with a water impervious backing, is placed
on a level surface. In the center of the sample, a 50
milliliter sample of a l.0% NaCl solution is deposited at the
rate of 7.0 milliliters per second. Absorbent paper toweling
is cut into three inch by five inch rectangles and a stack of
the paper toweling weighing approximately eighteen grams is
weighed and its dry weight is recorded. Sixty seconds after
the 1.0% NaCl solution has been deposited on the absorbent core
sample, a previously weighed stack of paper toweling is placed
on top of the absorbent core sample and a three inch by five
inch rectangular five pound weight is placed on top of the
paper toweling. After fifteen seconds, the weight is removed
from the then wet paper toweling which is reweighed. The
weight of the dry toweling is subtracted from the weight of the
wet paper toweling to give a skin wetness number corresponding
with the weight of 1.0% NaCI solution which was released by the
absorbent core into the paper toweling. A low number indicates
that an absorbent core has good retention of liquid so that
adjacent skin will stay relatively dry while a high number
indicates that liquid is readily released from an absorbent
core so that adjacent skin will become relatively wet.
WICKING
In this test, a seven inch by seven inch square sample of
absorbent core, with a water impervious backing, is placed on
a level surface. A 25.0 milliliter sample of 1.0% NaCl solution
including a blue dye is dispensed from a burette into the
canter of the sample at the rate of 10.0 milliliters per
second. The tip of the burette is ; inch from the surface of
the absorbent core sample, to prevent spattering of the test
liquid. One minute after the test liquid has been dispensed,
the perimeter of the wet spot is marked and measurements are
taken along a first axis and a second axis which is angularly
displaced ninety degrees from the first axis. Thus, the
results of this test are expressed in terms of two
measurements. A pair of small measurements for an absorbent
core indicates that the core does a relatively poor job of
distributing or wicking fluid so that fluid may puddle in one
12
area of the absorbent core wYiile the ab sorptive capacity of
remote, dry areas of 'the absorbent core is wasted. Conversely,
a pair of large measurements far an absorbent core indicates
that the core does a relatively good fob of wicking fluid so
that liquid will be well distribu7ted throughout the absorbent
core.
TABLE .I
ABSORBENCx SKIN WETNESS WICKING
(time in sec- (grams of (side-to (tap to
li-
onds until quid absorbedside die- bottom
fully absor- by toweling) meter of diameter
bed) licruid) of lic,~
EXAMPLE 1 2 . 3 12 > 4 ao 6 ea
53/
~'
COREA 1.5 19.0 4" 4"
COREB 1. 7 19 3 ~/ 3 ~
3 " "
. z /z
COREC 5.5 9.0 4~/ 4~
e' ~0
r, /2
COREC 5.0 --- _____ _____
COREC* --_ 2 3~/ 4~
2 'o 'e
. z /4
CORED 1.8 12 3~/ 3'
1 9' "
. z /z
COREE 1.4 11.3 3" 3~/4"
CORE F 1.3 __- _____ _--_-
CORE F* -_- 8 . 4 5/4'0 4 ai
CORE G 2.0 14.2 31/G~' 23/4~~
(Note: the core idewtificatians which are follawed by an
asterisk represent absorbent cores which were produced from
laminate from a different batch than the laminate which was
incorporated in the other absorbent cores for which test
results are reparted in Table I. As a comparison of the skin
wetness numbers for the first and third "Core C" struc4ures
suggests, the laminate which was incorporated in the cores
marked by an asterisk had a higher concentra~tian of super
absorbent polymer than the laminate which was incarporated in
the other cores. Accordingly, comparisons between results for
cores marked by an asterisk and cares which are not so marked,
should take this into account.)
The results set forth in Table I for absorbency
demonstrate that unembossed Core C has relatively poor
absorbency, while the core of Example 1 has relatively good
'~~~~a~~'~..
I3
absorbency. Of the cores that included a layer of laminate,
only Core F had a better absorbexicy number than the Example 1
core. It is theorized that the channel areas in Example 1
promote a rapid absorption of liquid through the laminate layer
into the fluff layer. Core F, embossed with flat rollers,
simulates the channels in Example 1 and the rapid absorption
of liquid into Core F supports the theory that there is very
fast absorption through 'the channels. There is a drawback
to the structure of Core F, however, and this is demonstrated
by a comparison of Skin Wetness numbers for Core C* and Core
F*. Core C* only gave up 2.2 grams of 3.iquid, while Core F*
gave up 8.4 grams. This indicates that Core C* with no channels
retains liquid much better than Core F* which corresponds with
100 channels. Thus, after 1 minute, liquid can flow back
through the laminate, owt of Core F*, whereas Core C* with no
channels gave up very little liquid in the Skin Wetness test.
The embossing pattern of the Example I core includes a
continuous network of channels which exhibits a demonstrated
ability to promote good wicking. In fact, Example 1 core had
the best wicking numbers although, as indicated in Table I, a
direct comparison between Cores C* and F* and the other cores
is unwarranted.
additional samples of cores were separateZ.y produced and
tested. The additional cores corresponded with the Example I
core, Core E and Core C. Same of the cores corresponding with
Core C and the Example I core were subjected to the Skin
Wetness test described above while others of those cores were
subjected to a modified Skin Wetness test in which the toweling
and the five pound weight were placed on the specimens ten
minutes after wetting, instead of one minute after wetting.
The results are set Earth below in Table II.
T.~~E TI
1 MINUTE 10 MINUTE
SKIN WETNESS SKIN WETNESS
(grams) (grams)
Example I 6.7 3.0
Core C 3.5 1,g
~s~~~~~~~~
14
The results set forth in Table TI demonstrate that 'the
super absorbent polymer continues to absorb liquid after one
minute after a wetting. Accordingly, over time, the Skin
Wetness per.foranance of the Example I core approaches that of
Core C. One minute after wetting, 'the Example T core gave up
3.2 grams more of liquid than Core C while, ten minutes after
wetting, the Example I core gave up only 1.4 grams mare of
liquid than Core C. These results demonstrate that the Example
I core, in addition to exhibiting much better Absorbency than
Core C, exhibits Skin Wetness performance which is comparable
to Core C, ten minutes after wetting.
An additional set of core samples were separately produced
and tested for their ability to absorb multiple wettings. The
test procedure corresponded with the Absorbency test procedure
outlined abave, except that, before the timer is started and
ten minutes after the initial wetting, an additional 10
milliliters of liquid was deposited on the core. Then, the
timer was started and the time required for the second ten
milliliter wetting to be absorbed was recorded. The results of
this test, fox cores corresponding with Example I, Core B and
Core C, are set forth in Table III.
ThE ITI
ABSORBEPICY (for a second 10 ml wetting)
(seconds)
Example T 19.6
Core B 6.0
Core C a120.0 (not all liquid was absorbed
after 2 minutes)
The results set forth in Table III suggest that the
channels in the Example I core continue to serve as transfer
sites through which liquid can be absorbed, even after an
initial wetting. Core C, on the other hand, exhibits an
inability to absorb a second wetting. This is believed to be
due to °°gel-blocking°° where swollen, gelled
super absorbent
polymer particles coalesce to form a layer which blocks
additional liquid from being absorbed by the core. Although
Core B has excellent Absorbency for a second wetting, Core B
~~~ ~~~ ~ ~~3~9.
cannot hold liquid under pressure, as shown by the data in
Table I.
With reference to FIG. 7, the absorptive components of an
absorbent product according to a second embodiment of the
5 invention are indicated generally at 70. In this embodiment,
the absorptive components 70 comprise an upper layer 72 and a
lower layer 74 of thick, air-laid tissue and, on top of the
layer 74, a layer of super absorbent polymer particles,
represented by dots 76 in the middle and the four corners of
10 the layer 74. The polymer particles can be relatively evenly
distributed over the entire layer 74 although the polymer :Layer
need not extend to the reaches of the two ends, 78 and 80 of
the layer 74. With the polymer powder in place on the layer
74, the layer 72 is united with the layer 74 and embossed to
15 produce an absorbent core 82, shown in FIG. 8.
A preferred embossing pattern is represented by bars 84
in the middle and the four corners of the core 82. The bars
84 correspond with areas of compression created during the
embossing step. Surrounding the bars 84 are uncompressed,
tufted areas. The side of the core 82 not illustrated in FIG.
8 lass a smooth surface.
With reference to FTG. 9, a tissue wrapping operation is
illustrated in which tissue paper 8~ is wrapped around the
absorbent core 82. When. the core 82 is completely wrapped,
excess tissue 86 is trimmed and the ends of the wrapped tissue
86 are glued or otherwise secured to produce a seam 88, shown
in FIG. 10. The wrapped core 82 is slit to define
lateral regians 90 which are folded inwardly, opposite the seam
88, to produce an absorbent insert 92. When the lateral
regions are folded inwardly, a smaoth surface 92 is exposed.
The slitting and folding steps are controlled so that a
substantial gap remains between the edges of the lateral
regions 90 to define a central region 94. The exposed surface
in the central region 94 includes compressed areas represented
by the bars 84. An absorbent article can be produced from
the absorbent insert 92, by sandwiching it between a water
impervious backing sheet 98 and a non-woven facing sheet 100.
Lines 102 of hot melt adhesive are applied~to the backing sheet
98 to adhesively secure it to the absorbent insert 92 and the
16
facing sheet 100. If desired, elastic means (not shown)
corresponding with the means 46 (FIG. 5) can be applied to the
backing sheet 98 (FIG. 11) to produce gathers in a finished
absorbent product.
After the insert 92 has been assembled between the backing
sheet 98 and the facing sheet 100, leg cut outs would be
trimmed from the assembly, as discussed above with reference
to FIG. 6.
7Referring now to FIG. 12, the direct deposition of a super
1o absorbent polymer onto a fluff layer 110 will now be described.
Layer 110 is a relatively thick layer of moisture absorbing
material, such as cellulose fluff, fluffed wood pulp, batting
or the like.
Apparatus for use in depositing polymer powder on the
fluff layer 110 comprises water spray means indicated generally
at 112 and polymer deposition means indicated generally at 7.14.
The water spray means comprises a spray head 116 to which water
is supplied through conduit 118 at a constant pressure which
may be monitored or controlled by a pressure controller 120.
The polymer deposition means 114 comprises a trough 222 for
holding polymer powder, indicated at 7.24, and deposition rate
control means 12f> for adjusting the rate at which polymer
powder 124 is released from the trough 122. Beneath the
polymer deposition means 7.7.4, specifically, the trough 122,
there is provided a vacuum integration means 128 for drawing
a vacuum below the fluff layer to draw polymer powder 124 into
the fluff layer where the fluff fibers will engage and retain
it. A central conduit 130 in the vacuum integration means 128
can be connected to a suitable vacuum source (not shown).
The water spray means 112 and the polymer deposition means
114 are positioned and sized to spray water and deposit polymer
powder on the fluff layer 110 in a central region 132 defined
between dotted lines 134. The polymer deposition means 114 may
be operated continuously, or intermittently so that discreet
absorbent portions of the central region 132 having polymer
powder 324 deposited thereon are separated by discreet
portions of the central region 132 which do not have polymer
powder 114 deposited thereon. Continuous operation of the
polymer deposition means 114 will produce a continuous layer
1 °7
of polymer powder 124 in the central region 132 of a piece 136
which has been cut from the fluff layer 110, as shown in FIG.
13. Intermittent deposition of polymer powder 124 could be used
to produce a piece, like the piece 136, except that the polymer
powder 124 would not extend all of the way to the edges; it
would be recessed from all four sides of the piece.
During operation of the FTG. 12 apparatus, fluff material
constituting the layer 110 is advanced from right to left,
passing first under the polymer deposition means 114 and 'then
under the water spray means 112. By controlling the rate of
deposition of polymer powder 124, relative to the rate at which
the fluff layer is advanced, one can achieve a desired
concentration of palymer powder i:n the fluff material 110. In
the central region, a concentration of approximately 130 grams
of polymer (Aridall 1080 polyacryiate super absorbent polymer)
per square meter is a good concentration. More or less polymer
may be used, depending on a number of factors including the
identity and capacity of the super absorbent polymer and the
intended use.
After the polymer powder 124 is deposited in the central
region 132 of the layer 110, water or an aqueous solution of
a water soluble adhesive is sprayed on the central region. The
water or the like promotes bonding between the fibers
constituting the layer 110 and the polymer powder. Additionally
the water or the like plays an important role during an
embossing operation which is described below.
With further reference to FIG. 13, there is illustrated
a layer 138 of heavy tissue, corresponding in size with the
central region 132. As illustrated in FIG. 14, the tissue layer
138 is positioned on the piece 136 so that it covers the
central region 132 and the polymer powder 124 deposited
thereon. The layer 138 is positioned on the same side of the
fluff layer 110 as that on which the polymer powder 124 was
deposited. The layer 138, as well as the layer 24 (FIG. 1) can
be single ply or double ply. If single ply, the tissue should
have a basis weight of between 14 pounds and 18 pounds. If
double ply, the tissue should have a basis weight of between
14 pounds and 22 pounds. A single ply tissue with a basis
weight of 14.5 pounds produces very good results. The tissue
18
layers 138 and 24 (FIG. 1) should consist of a tissue with good
stretchabilityp 18~ to 33~ machine direction stretch is
preferred.
In FIG. 14, upper and lower tissue layers 140 and 142 are
positioned to be brought into cowtact with 'the upper and lower
surfaces of the piece 136. The tissue layers 140 and 142 are
light by comparison with the tissxre layer 138. A 12 pound basis
weight wet strength tissue is preferred for the layers 140 and
142 as well as for the layers 28 and 30 (FIG. 2) and the tissue
wrap 86 (FIG. 9).
After the tissue layers 140 and 142 are brought into
contact with the piece 136, the components are subjected to an
embossing step. A smooth roller (not shown) is applied to 'the
lower tissue layer 142 and a patterned roller (not shown) is
applied to the opposed, upper tissue layer 140 to produce an
embossed absorbent core 144. A suitable diamond embossing
pattern is shown in FIG. 15, reflected in the pattern shown on
the surface of the tissue layer 140. The embossing pattern on
the embossing die (not shown) applied to the upper tissue layer
140 produces a pattern of channels 146 in the tissue layer 140,
the tissue layer 138, and the fluff layer 110. As is explained
above, these channels 146 constitute transfer sites through
which liquid is absorbed quickly from above the upper tissue
layer 140, through the tissue layer 138, to the fluff layer 110
where it will be absorbed, eventually by the polymer powder 124
dispersed therein. The channels 146 are iwterconnected in a
continuous network which promotes excellent wicking
characteristics.
In the channels 146, there is a high density interface
between the tissue layers 138 and 140 and the fluff layer 3.10.
In this interface, there is a physical bond between the layers
138, 140 and 110 which gives the absorbent core 144 physical
3ntegri~ty. In the areas between the channels 146, the layers
138, 140 and 110 have a lower density than these layers have
in the channels 146. The polymer powder 124 is, in effect,
laminated between the tissue layer 138 and the fluff layer 130.
This core construction is advantageous because migration of the
powder 124 is resisted while swelling of the powder i24 is
relatively unrestricted. The channels 146 promote fast
1g
absorption. This core construction also provides very high
capacity with an ability to absorb multiple wettings. These
characteristics are believed to be due, in part, to what
amounts to a three dimensional distribution of polymer powder
in the core 144, as opposed to a two dimensional distribution
of polymer powder in absorbent products which include a super
absorbent polymer laminated between two tissue layers. In the
former, there is a degree of freedom for the polymer to expand
into the fluff layer whereas, in the latter, the polymer is
stuck between two tissue layer.~s in a substantially two-
dimensional plane. For example, Core C is an absorbent core
which included a super absorbent laminate with super absorbent
polymer sandwiched between tissues layers. As the results set
forth in TABLE TIT indicate, core C could not absorb a second
wetting, even after two minutes. Tt appeared that the super
absorbent polymer in the laminate layer in Core C had expanded
and coalesced to form a two-dimensional barrier layer through
which liquid could not pass. Tn contrast, the super absorbent
polymer in the core 144 is riot confined in a two-dimensional
plane. Consequently, the core 144 can absorb multiple wettings
The core 144 has good skin wetness performance, i.e., it
retains fluid well, even under pressure. It is believed that
the three-dimensional distribution of super absorbent polymer
in this core construction allows the polymer to have greater
capacity because there is more room for the polymer to expand.
Once liquid is taken up by the super absorbent polymer, the
liquid is not released, even under pressure. Liquid that is
not picked up by the polymer will be held in the fluff layer.
Although liquid can be squeezed nut of fluff, this core
construction resists the squeeze out of liquid, back through
the upper tissue layer 140. The polymer powder in the core 144
is concentrated on and near the upper surface of the fluff
layer 110. When the absorbent core is not under pressure, the
polymer is distributed in three-dimensions, as discussed above.
However, when the core is compressed after a wetting, the
gelled, swollen polymer particles will be brought into close
contact forming a barrier layer to prevent the squeeze out of
liquid through the upper tissue layer 140.
~~~a~~~,..
The embossing step can be carried out. advantageously with
approximately 50 to 175 lbs of pressure per lineal inch of the
embossing rollers. A variety of patterns would be suitable for
the patterned embossing roller, beside the one reflected in the
5 upper tissue layer 140 shown in FIG. 15.
It will be appreciated that the manufacturing steps
described above with reference to FIGS. 12-15 can be applied
to bulk materials supplied, for example, from rolls.
Specifically, the fluff layer 110, the tissue layers 138, 140
10 and 142 can be manufactured into an embossed, absorbent core
144 of infinite length which can later be cut to appropriate
length and incorporated into an absorbent product according to
the instant invention. After the absorbent core 144 has been
embossed, it is preferably subjected to a de-bulking aperation
15 in which it is passed between 'two compression rollers (not
shown). This step adds further integrity to the embossed
absorbent core 144 and promotes more economical packaging by
producing thinner absorbent products.
Referring now to FIG. 16, the embossed absorbent core 144
20 is illustrated after ears 148 have been trimmed therefrom to
produce an absorbent insert 150, with leg cut outs 152, for
incorporation in an absorbent product. The cut outs 152 extend
inwardly toward, but terminate just short of, the central
region 132 defined between the dotted lines 134. The eaxs 148
can be recycled, if desired, to yield material suitable for
producing additional fluff layers 110. The trimming can be
carried out with a die-cutter which may include a cutter for
cutting the embossed absorbent core 144 to produce an absorbent
insert 150 of a given length. Alternatively, a separate cutter
may be used to cut absorbent core material to an appropriate
length.
As used hereinabove, the term fluff refers to a web made
up of loose fibers. It is also intended to encompass composite
webs made up of such fibers and including other materials such
as synthetic fibers. For example, Hercules distributes, under
the name Pulpex, a polyethylene/polypropylene blend of fibers
which can be advantageously incorporated into a fluff layer.
Pulpex, in amaunts of five percent can be incorporated into
fluff and heated to improve the integrity of tire fluff layer.
21
With reference to FIG. 17, ano~th~er embodiment of an
absorbent core comprises a layer 1.60 of laminate and piece 162
consisting of a fluff layer 164 and super absorbent polymer
powder 166 deposited in a central region 168 of the fluff layer
164. The piece 162 can be readily produced on apparatus of the
type described above with reference to FIG. 12. Tt will be
appreciated that the apparatus of FIG. 12 can be operated so
that it intermittently deposits polymer powder 166 on the
central region 168 of the layer of fluff 164. In that case,
the layer of polymer powder 166 would terminate short of the
ends of the piece 162, as well as terminating short of the
sides of the piece 162, as shown in FIG. 17.
The laminate layer 160 comprises super absorbent polymer
powder dispersed in and supported on a heavy tissue.
Preferable, the layer 160 of laminate is Gelok 6000 single
ply/double ply, a laminate consisting of 1080 polyacrylate
super absorbent polymer sandwiched between a single ply of 14
pound basis weight tissue and two sheets of 10.5 pound basis
weight tissue. The laminate layer corresponds in size with the
central region 168 where the polymer powder 166 is deposited.
As illustrated in FIG. 18, the laminate layer 160 is positioned
on the piece 162 so that it covers the cewtral region 168 and
the polymer powder 166 deposited thereon. The laminate layer
160 is positioned on the same side of the fluff layer 164 as
that on which the polymer powder 166 was deposited. The
laminate layer can be single ply or double ply. If single ply,
the tissue should have a basis weight of between 14 pounds and
18 pounds. If double ply, the tissue should have a basis
weight of between 14 pounds and 22 pounds. A single ply tissue
with a basis weight of 14.5 pounds produces very good results.
The laminate layer 160 should consist of a tissue with good
stretchability; 18% to 33% machine direction stretch is
preferred.
In FIG. 18, upper and lower tissue layers 170 and 172 are
positioned to be brought into contact with the upper and lower
surfaces of the piece 162. Optionally, a single ply of heavy
tissue (not shown) can be positioned between the piece 162 and
the tissue layer 170. The tissue layers 170 and 172 are light
by comparison with the tissue incorporated into the laminate
22
layer 160. A 12 pound basis weight wet strength tissue is
preferred for the layers x.70 and 172.
After the tissue layers 170 and 172 are brought into
contact with the piece 162, the components are subjected to an
embossing step. A smooth roller (not shown) is applied to the
lower tissue layer 172 and a patterned roller (not shown) is
applied to the opposed, upper tissue layer 170 to produce an
embossed absorbent core 174 shown in FIG 19. A suitable
diamond embossing pattern is shown in FIG. 19, reflected in the
pattern shown on the surface of the tissue layer 170. The
embossing pattern on the embossing die (not shown) applied to
the upper tissue layer 170 produces a pattern of channels 176
in the tissue layer 170, the laminate layer 160, and the fluff
layer 164. These channels 176 constitute transfer sites
'through which liquid is absorbed quickly from above the upper
tissue layer 170, through the laminate layer 160, to the fluff
layer 164 where it will be absorbed, eventually by the polymer
powder 166 dispersed therein. The channels 176 are
interconnected in a continuous network which promotes excellent
wicking of deposited fluid, through the channels, to portions
of the embossed absorbent core 174 remote from the deposit
site. The polymer powder which is deposited in the fluff layer
locks in liquid which is absorbed throughout the channels 176
to yield excellent skin dryness characteristics for the
absorbent core 174, while the channels 176 provide excellent
absorbency characteristics. Moreover, as demonstrated in Table
III, an absorbent core (Example I) which has been embossed to
provide channels, can absorb multiple wettings.
In the channels 176, there is a high density interface
between the laminate layer 160, the tissue layer 170 and the
fluff layer 164. In this interface, there is a physical bond
between the layers 160, 170 and 164 which gives the absorbent
core 174 physical integrity. In the areas between the channels
176, the layers 160, 170 and 164 have a lower density than
these layers have in the channels 176. The polymer powder 166
that has been deposited on the fluff layer 164 is, in effect,
laminated between the laminate layer 160 and the fluff layer
164 . This core construction is advantageous because migration
of the deposited powder 166 is resisted while swelling of the
~r~~~,i~~~'~.
23
deposited powder 166 is relatively unrestricted. The channels
176 provide the absorbent insert with excellent absorbency.
This coxe construction also provides very high capacity with
an ability to absorb multiple wettings. ~.Chese characteristics
are believed to be due, in part, to what amounts to a three
dimensional distribution of polymer powder in the core 144, as
opposed to a two dimensional distribution of polymer powder in
absorbent products which includes a super absorbent polymer
laminated between two tissue layers. Thus, the absorbent core
174 combines the high capacity afforded by super absorbent
polymer dispersed in fluff with tlhe excellent skin wetness and
core integrity afforded by the embossed laminate/fluff
structure.
The embossing step can be carried out advantageously with
approximately 50 to 175 lbs of pressure per lineal inch of the
embossing rollers. A variety of patterns would be suitable for
the patterned embossing roller, beside the one reflected in the
upper tissue layer 170 shown in FIG. 19.
It will be appreciated that the manufacturing steps
described above with reference to FIGS. 17-19 can be applied
to bulk materials supplied, for example, from rolls.
Specifically, the fluff layer 164, the laminate layer 160, the
tissue layers 170 and 172 can be manufactured into an embossed,
absorbent core 174 of infinite length which can later be cut
to appropriate length and incorporated into an absorbent
product according to the instant invention. After the
absorbent core 174 has been embossed, it is preferably
subjected to a de-bulking operation in which it is passed
between two compression rollers (not shown). This step adds
further integrity to the embossed absorbent core 174 and
promotes more economical packaging by producing thinner
absorbent products.
Referring now to FIG. 20, the embossed absorbent core 174
is illustrated after ears 178 have been trimmed therefrom to
produce an absorbent insert 180, with leg cut outs 182, for
incorporation in an absorbent product > The cut outs 182 extend
inwardly toward, but terminate just short of, the layer 160 of
laminate. The ears 178 can be recycled, if desired, to yield
material suitable for producing additional fluff layers 164.
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The trimming can be carried out with a die-cutter which may
include a cutter fox cutting the embossed absorbent core 174
to produce an absorbent insert 180 of a given length.
Alternatively, a separate cutter may be used to cut absorbent
core material to an appropriate length.
The absorbent inserts 150 and 180 can readily be
incorporated in a diaper product ;such as the absorbent product
54 shown in FIG. 6. Alternat9.vely, these inserts can be
sandwiched between a layer of non-cloven material and poly
backing to produce pad products, such as a bed pad, without leg
cut outs 56 as provided for the absorbent product 54.
The foregoing description is intended to enable those
skilled in the art to practice the presemt invention and
constitutes the best mode presently known for practicing the
invention. Undoubtedly, modifications will occur to those
skilled in the art, and such modifications may be resorted to
without departing from the spirit and scope of the invention
disclosed herein and claimed below.
