U.S. patent application number 10/118555 was filed with the patent office on 2002-08-15 for method of manufacturing a disposable absorbent article having a reinforced fastening tape landing zone.
Invention is credited to Glaug, Frank S., Waksmundzki, Andrew.
Application Number | 20020111599 10/118555 |
Document ID | / |
Family ID | 24080040 |
Filed Date | 2002-08-15 |
United States Patent
Application |
20020111599 |
Kind Code |
A1 |
Glaug, Frank S. ; et
al. |
August 15, 2002 |
Method of manufacturing a disposable absorbent article having a
reinforced fastening tape landing zone
Abstract
A disposable absorbent brief is provided with a reinforced
fastening tape landing zone which permits repeated removal and
reattachment of the fastening tape for adjustment of fit. The
backing sheet of the brief is a relatively thin and inexpensive
sheet material which has at least one relatively thin and
inexpensive, adhesively-secured strip of landing zone reinforcement
sheet material. The reinforcement strip provides the strength
required to allow tape removal and reattachment without causing
tearing of the reinforcement strip or backing sheet or separation
of the reinforcement sheet from the backing sheet. The adhesive
layer is applied to the reinforcement sheet stock by slot coating
as a continuous and uninterrupted layer on the reinforcement strip
in a cost-effective and efficient process.
Inventors: |
Glaug, Frank S.; (Chester
Springs, PA) ; Waksmundzki, Andrew; (Jackson,
NJ) |
Correspondence
Address: |
HOWSON AND HOWSON
ONE SPRING HOUSE CORPORATION CENTER
BOX 457
321 NORRISTOWN ROAD
SPRING HOUSE
PA
19477
US
|
Family ID: |
24080040 |
Appl. No.: |
10/118555 |
Filed: |
April 8, 2002 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10118555 |
Apr 8, 2002 |
|
|
|
09522235 |
Mar 9, 2000 |
|
|
|
Current U.S.
Class: |
604/389 ;
156/256; 156/270 |
Current CPC
Class: |
Y10T 156/1085 20150115;
Y10T 156/1062 20150115; A61F 13/60 20130101 |
Class at
Publication: |
604/389 ;
156/270; 156/256 |
International
Class: |
B32B 031/00 |
Claims
We claim:
1. A method of manufacturing a disposable absorbent article with a
reinforced tape fastening landing zone, comprising the steps of:
coating a continuous elongate strip of landing zone reinforcement
material with adhesive so that the adhesive forms an elongate,
continuous and uninterrupted layer on said material; cutting said
adhesive-coated continuous elongate strip of landing zone
reinforcement material to produce a plurality of individual-sized
landing zone reinforcement strips; and applying individual-sized
landing zone reinforcement strips onto outer surfaces of backing
sheets of the disposable absorbent articles, and securing said
reinforcement strips to said backing sheets by said adhesive.
2. A method according to claim 1, wherein the cutting step is
carried out by means of a rotary die.
3. A method according to claim 1, wherein the adhesive is a
pressure sensitive adhesive.
4. A method according to claim 1, wherein the coating step is
carried out by transferring the adhesive from a chill roll onto the
elongate strip of landing zone reinforcement material.
5. A method according to claim 1, wherein said adhesive is
slot-coated onto one side face of said elongate strip such that
said entire face is coated with said elongate, continuous and
uninterrupted layer of adhesive except for a pair of opposite
elongate edge margins of said face of said elongate strip.
6. A method according to claim 1, wherein said adhesive is
transferred through an elongate, narrow slot onto a chill roll and
from the chill roll onto the elongate strip of landing zone
reinforcement material, and in which the adhesive is at a
temperature within a range of about 150.degree. F. to 350.degree.
F. when transferred onto the chill roll.
7. A method according to claim 1, wherein said elongate strip is a
strip of polypropylene having a thickness in a range of about
0.2-0.9 mil.
8. A method according to claim 7, wherein said backing sheet of the
disposable absorbent article is made of polyethylene having a
thickness in a range of about 0.3-0.9 mil.
9. A method according to claim 8, wherein a pair of
individual-sized landing zone reinforcement strips are adhesively
secured to each disposable absorbent article at different locations
on said backing sheet.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a division of application Ser. No.
09/522,235, filed Mar. 9, 2000.
FIELD OF THE INVENTION
[0002] This invention relates to disposable absorbent articles and
more particularly to improvements in adult incontinence briefs of
the kind utilizing fastening tapes with pressure-sensitive adhesive
for securing parts of the brief together in order to fit the diaper
to the person.
BACKGROUND OF THE INVENTION
[0003] Disposable absorbent articles, such as infant diapers and
adult incontinence products, are used to absorb body fluids and
waste materials of infants, children and adults. These products are
provided, for example, as briefs or undergarments, and have a
moisture absorbent pad covered on one side by a moisture-permeable,
body-contacting cover sheet and on the other side by a
moisture-impermeable or hydrophobic backing sheet. Typically, the
disposable absorbent article is fitted to the wearer by two or more
fastening tapes, which are permanently connected to, and extend
from, the outside surface of the backing sheet and are adhesively
secured to areas of the outside surface of the backing sheet known
variously as "target zones" or "landing zones."
[0004] After the disposable absorbent article is initially secured
on the wearer, adjustment is often necessary in order to obtain a
proper fit. Thus, after the fastening tapes are initially secured
to the landing zone, detachment and reattachment of the tapes are
required in order to carry out the desired adjustment. A backing
sheet which is too thin or weak will rip or become damaged when the
fastening tape is removed. Thus, to achieve the necessary strength
to permit tape removal and reattachment, the backing sheets of
disposable absorbent articles are generally made relatively thick.
For example, a backing sheet made from a polyethylene film having a
uniform thickness of 1.1 mils (0.0011 inch or 0.028 mm) has been
found to provide the required strength, even at the low end of the
film thickness range, to permit tape removal and reattachment
without causing excessive damage to the backing sheet. However, the
thickness of the backing material is important only in order to
avoid tearing the backing material when the tape is removed from
it. The use of thick backing sheet material results in significant
material costs, and thus, the backing sheet is not a "value-adding"
feature.
[0005] As an alternative to relatively thick and expensive backing
sheet materials, backing sheets have been provided with reinforced
landing zone areas to permit removal and reattachment of the
fastening tapes without ripping or otherwise damaging the backing
sheet. For example, U.S. Pat. No. 4,911,702 to O'Leary et al.
discloses a disposable absorbent adult brief having a backing film
with two "target tapes" on a backing having a thickness in the
range of 1.0 to 1.3 mil. FIG. 2 of the O'Leary patent illustrates a
prior art adult brief having four attachment tabs and two target
tapes, the stated purpose of which is to serve as attachment points
for the attachment tabs so that, if desired, they may be
repositioned without tearing the thin polyethylene backing
film.
[0006] U.S. Pat. Nos. 5,370,639, 5,024,672 and 5,236,429, to
Widlund, disclose a disposable diaper having a polyethylene backing
film onto which a plastic strip is glued, and to which
pressure-adhesive tapes are secured.
[0007] U.S. Pat. No. 5,026,446 to Johnston et al. discloses a
method of manufacturing a disposable diaper having a target strip.
The target strips are made of high-strength thermoplastic films
such as biaxially oriented polypropylene film or biaxially oriented
poly (ethylene terephthalate) film having a thickness of 0.6 to 1.6
mil. A roll of pressure-sensitive adhesive tape is first fed
through a metal roll and a counter rotating abrasive brush and is
then fed onto a vacuum wheel where it is cut into strips by a
rotary cutter. Each strip is adhered to a diaper web with pressure
applied by a rubber pad on a steel roll.
[0008] U.S. Pat. No. 4,710,190 to Wood et al. discloses a
disposable diaper having a reinforcement strip made of
polypropylene or poly (ethylene terephthalate) film having a
thickness of 0.4 to 3.0 mil. A bonding layer secures the strip to
the backing film when the strip and backing film are applied with
pressure and heat, such as, by a heating roll.
[0009] U.S. Pat. Nos. 4,753,649 to Pazdernik; U.S. Pat. No.
5,106,383 to Mulder et al.; U.S. Pat. No. 5,720,739 to Hilston et
al.; U.S. Pat. No. 5,649,921 to Arakawa et al. and U.S. Pat. No.
5,599,620 to Huskey disclose various other disposable diapers
having reinforcement strips adhesively secured to backing films.
U.S. Pat. Nos. 5,690,628 to Huskey et al.; U.S. Pat. No. 5,527,305
to Goulait et al.; U.S. Pat. No. 5,061,262 to Chen et al.; U.S.
Pat. No. 5,275,538 to Matsumoto et al. and U.S. Pat. No. 5,722,969
to Ito et al. disclose various other disposable diapers having
reinforced landing zones.
[0010] Although the aforementioned disposable absorbent articles
having reinforced landing zones, and their methods of manufacture,
may be satisfactory for their intended purposes, there remains a
need for an improved disposable absorbent article which permits
tape removal and re-fastening and which can be produced at lower
cost. There is also a need for an improved, more efficient and
cost-effective method of producing a disposable absorbent article
having a reinforced landing zone.
BRIEF SUMMARY OF THE INVENTION
[0011] The principal object of this invention is to provide a
disposable absorbent article, adapted to be worn on the person,
which has a reinforced landing zone permitting tape removal and
re-fastening, and which can be produced at a very low cost. An
additional object of this invention is to provide an efficient and
cost-effective method of producing a disposable absorbent article
having a reinforced landing zone.
[0012] The invention addresses the foregoing objects in a
disposable absorbent article comprising a thin, liquid-impermeable
backing sheet having a uniform thickness, preferably in the range
of 0.3 to 0.9 mil, and opposite inner and outer faces. An absorbent
layer is secured to the inner face, and tapes, secured to first and
second areas on the outer face of the backing sheet have portions
extending therefrom coated by a pressure-sensitive adhesive. The
pressure-sensitive adhesive is sufficiently aggressive and the
backing sheet is sufficiently thin, that if the tapes were adhered
by the adhesive directly to the outer face of the backing sheet,
they could not be removed consistently from the backing sheet
without ripping the backing sheet. Reinforcement sheets, which are
preferably of uniform thickness in the range of about 0.2 to 0.9
mil, are secured to the outer face of the backing sheet to
establish landing zones for attachment of the adhesive-coated
portions of the tapes. These reinforcement sheets are secured to
the outer face of the backing sheet respectively over third and
fourth, preferably rectangular, areas. The reinforcement sheets are
secured respectively to the third and fourth areas of the outer
face of the backing sheet by layers of adhesive which are
uninterrupted widthwise and lengthwise over each of the third and
fourth areas.
[0013] A key to the achievement of highly superior results with the
invention is the application of the layer or layers of adhesive to
the reinforcement sheets by slot coating. Slot coating produces the
uninterrupted area coverage, and thereby prevents gaps in the
adhesive layer which could result in ripping of the reinforcement
sheets or separation of the reinforcement sheets from the backing
sheet. It also enhances efficiency in adhesive usage, produces a
uniform adhesive coating thickness, and provides well-defined
margins along opposite edges of the reinforcement strips, thereby
avoiding areas of exposed adhesive which could result in portions
of the article adhering to one another or to other, similar
articles.
[0014] Another key to the achievement of highly superior results
with the invention is the application of hot melt adhesive to a
thin, heat-sensitive polymeric film. One method to achieve this is
first to "slot coat" the hot melt adhesive to a low friction,
smooth roll (made of PTFE, or having a silicone or PTFE coating),
which is cooled as well. Rolls of this kind are known as "chill
rolls." The chill roll is then rotated to transfer coat the lower
temperature hot-melt adhesive to a polymeric film. The hot melt
adhesive, which is a pressure-sensitive adhesive, sticks to the
higher friction polymeric film and is thus transferred completely
from the chill roll to the film.
[0015] Other objects, details and advantages of the invention will
be apparent from the following detailed description when read in
conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a perspective view of a disposable absorbent brief
secured on a wearer according to the invention;
[0017] FIG. 2 is a plan view of the disposable absorbent brief of
FIG. 1 disposed in a flat condition; and
[0018] FIG. 3 is a cross-sectional view of the disposable absorbent
brief taken on plane 3-3 of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The invention will be described with reference to an adult
incontinence brief, in which the advantages of the invention are
most conspicuous. However, it will be apparent from the description
which follows, that advantages of the invention can be realized in
other absorbent articles, including infant diapers.
[0020] The disposable absorbent article 10 has a construction which
permits the article to be adjusted to ensure a proper and
comfortable fit. To this end, the article 10 has a reinforced
backing sheet 12 which permits removal and reattachment of tape
fasteners 14 so that, after the article is initially positioned on
the wearer, it can be readily adjusted for a proper and comfortable
fit.
[0021] Typically, material and manufacturing costs are relatively
high for a disposable absorbent article having an extra-strength,
or reinforced, backing sheet. A significant aspect of this
invention is that the absorbent article 10 is inexpensive to
produce even though it utilizes a reinforced backing sheet.
Material costs are minimized by a unique construction and
manufacturing costs are minimized by a novel and cost-effective
method of manufacture. The construction and manufacturing technique
can be utilized for both infant diapers and adult briefs, but are
particularly advantageous in the manufacture of adult briefs
because of the requirements for larger sizes of sheet material and
a greater number of relatively strong fastening tapes.
[0022] In FIG. 2, the outer face of the backing sheet 12 is seen in
full, and the moisture absorbent pad 16 is shown in broken lines on
the opposite, inner face of the backing sheet. The pad is secured
to the inner face of the backing sheet, and covered by a
moisture-permeable, body-contacting cover sheet (not shown) which
may be coextensive with the backing sheet, or alternatively large
enough to cover the absorbent pad but smaller than the backing
sheet so that the backing sheet has a margin extending beyond the
edges of the moisture-permeable cover sheet. As best illustrated in
FIG. 1, the backing sheet 12 has an abdominal portion 12a and a
rear portion 12b, and as best illustrated in FIG. 2, the rear
portion of the backing sheet has opposite side edges 12c and
12d.
[0023] Plural fastening tapes 14 extend laterally from the rear
portion 12b of the backing sheet, beyond the edges 12c and 12d so
that, when the brief 10 is positioned on the wearer, the fastening
tapes 14 extend forward and can be attached to the abdominal
portion 12a of the backing sheet. Preferably, an adult brief 10, as
illustrated, will include a pair of fastening tapes 14 extending
from each backing sheet side edge, 12c and 12d. A
pressure-sensitive adhesive on the inward facing sides 14a of the
fastening tapes 14 permits the tapes to be secured to the backing
sheet to attach the brief 10 to the wearer, and permits subsequent
removal and reattachment.
[0024] The backing sheet 12 has two reinforced landing zones 18 to
which the fastening tapes 14 may be attached. Each landing zone 18
is provided by a separate strip of material 20 permanently secured,
by a layer 22 of adhesive, to the abdominal portion 12a of the
outer face of the backing sheet. The layer of adhesive is also
illustrated in FIG. 3, and its area of coverage is illustrated by
dotted lines in FIG. 2. Reinforcement strip 20 must be secured to
the backing sheet 12 in such a way as to avoid ripping of the strip
20 or the backing sheet 12, and also to avoid separation of the
strip 20 from the backing sheet 12, when the fastening tapes 14 are
pulled away from the landing zone 18 for adjustment. For example,
if the adhesive layer 22 is not continuous, air pockets between the
reinforcement strip 20 and backing sheet 12 will allow the
reinforcement strip 20 to tear and/or separate from the backing
sheet 12. Therefore, an important aspect of the invention is that
the adhesive layers 22 are uninterrupted widthwise and lengthwise
over the areas which they cover. Thus, if the layer of adhesive is
rectangular, which is the preferred configuration for manufacturing
efficiency, the adhesive layer covers the entire area within the
borders of the rectangle. More generally, for a rectangular
adhesive layer, or any other suitable shape, the adhesive layer is
uninterrupted lengthwise and widthwise if substantially any
straight path lying in the plane of the layer of adhesive and
intersecting an edge of the adhesive layer, passes through adhesive
substantially continuously and without interruption by a gap in the
adhesive layer until it finally exits from the adhesive layer
through an edge on the other side of the adhesive layer. Thus, the
border of any adhesive layer will generally be either straight or
convex at all locations. However, minor concavities are not
objectionable.
[0025] Preferably, the continuous and uninterrupted layer of
adhesive 22 is applied to the reinforcement strips 20 by a
slot-coating process. In this process, the adhesive layer 22
extends the full length "L" of the reinforcement strip 20, but
slightly less than the full width "W" of the reinforcement strip 20
as best illustrated in FIG. 2 by dotted lines. Thus, a pair of side
edge margins, 20a and 20b, of the reinforcement strip 20 freely
extend from the backing sheet 12 along opposite edges of the
adhesive layer 22. The margins, 20a and 20b, do not form a part of
the landing zone area 18 and are located so that the tape fasteners
14 are never secured to them. The application of adhesive to the
strip material by slot coating results in several advantages.
First, slot coating produces a continuous adhesive layer without
gaps or air pockets which would allow ripping or separation to take
place upon removal of the attachment tapes. Second, slot coating
permits application of the adhesive in such a way as to provide the
narrow margins 20a and 20b in the reinforcement strips along
opposite edges of the adhesive area. These narrow margins avoid
exposed adhesive that could cause parts of the article 10 to adhere
to one another or cause adjacent articles 10 to adhere to each
other in manufacture, or in the process of packaging the articles.
Third, slot coating improves the efficiency of adhesive usage by
avoiding application of adhesive to coating machine parts and to
areas where it is not needed, and by producing a uniform adhesive
coating having an optimum thickness.
[0026] Another important aspect of the invention is that the use of
a continuous and uninterrupted layer of adhesive 22 permits the use
of relatively thin and inexpensive sheet materials for the backing
sheet 12 and reinforcement strips 20. For example, the sheet
material for either the backing sheet or the reinforcement strips
can be polyethylene, polypropylene, a co-polymer blend, co-extruded
film, polyester or polyurethane. The backing sheet and
reinforcement strips can be made of the same sheet material or of
different sheet materials. Preferably, the backing sheet 12 has a
uniform thickness of about 0.3 to 0.9 mils, and each reinforcement
strip 20 has a uniform thickness of about 0.2 to 0.9 mils.
[0027] By way of example, one contemplated embodiment of article 10
utilizes a backing sheet 12 made of polyethylene having a thickness
of 0.8 mils and reinforcement strips 20 made of polypropylene
having a thickness of 0.5 mils. In this embodiment, the combined
thickness of the polyethylene and polypropylene components of each
landing zone area 18 is 1.3 mils, and the thickness of the
remaining portions of the backing sheet is 0.8 mils. Thus, the
material usage in the construction of the backing sheet is
optimized by reinforcing only the area to which the tape fasteners
14 are likely to be attached in normal use. In addition, the use of
a continuous and uninterrupted layer of adhesive 22 permits further
reduction in the thickness of the reinforcement strip material. The
embodiment is thereby produced inexpensively, but permits repeated
removal and reattachment of the attachment tapes.
[0028] In the manufacture of the disposable absorbent article 10, a
continuous, elongate, advancing strip of landing zone reinforcement
material is transfer coated with a pressure sensitive adhesive.
Preferably, a slot-coating process is utilized, in which an
adhesive is extruded through an elongate narrow slot onto a PTFE
chill roll or a PTFE- or silicone-coated chill roll, and than
transferred to the advancing reinforcement material. To this end,
the slot extends transversely relative to the advancing elongate
strip of material so that the reinforcement material is transfer
coated with a continuous elongated layer of adhesive 22. The width
of the slot is slightly less than the width of the reinforcement
material so that the opposite side edge margins 20a and 20b of the
reinforcement material are not covered by the adhesive layer.
Slot-coating ensures that the layer of adhesive 22 is continuous
and uninterrupted, and provides for cost-effective and efficient
coating of the reinforcement material and avoidance of exposed
adhesive.
[0029] Preferably, the adhesive is a low-temperature processing,
pressure sensitive, construction adhesive. An example of such an
adhesive is an adhesive sold under the trademark COOL-LOK by
National Starch & Chemical of Bridgewater, N.J.
[0030] In the slot-coating process, when the temperature sensitive
adhesive is transferred from the elongate narrow slot to the chill
roll, the temperature of the adhesive is in the range of about
150.degree. to 350.degree. F. (66.degree. to 177.degree. C.),
preferably at approximately 200.degree. F. (93.degree. C.). The
temperature of the adhesive is at a lower level when it is
transferred from the chill roll onto the elongated strip of landing
zone material.
[0031] After the elongate strip of landing zone reinforcement
material is coated with adhesive, the material is transferred onto
a vacuum roll and then cut on a rotary die to produce multiple,
individual landing zone reinforcement strips 20. The individual
landing zone reinforcement strips 20 are applied directly onto the
outer faces of backing sheets 12
[0032] The above-described disposable absorbent article and method
of manufacture of the article provide a brief having a reinforced
backing sheet which permits repeated removal and reattachment of
fastening tapes. Material costs and manufacturing costs are
minimized by utilizing thin and inexpensive sheet materials and a
applying a continuous and uninterrupted layer of pressure sensitive
adhesive onto the reinforcement strips by slot-coating.
[0033] While a preferred disposable absorbent article and method of
its manufacture have been described, various modifications can be
made to the brief construction and to the method of manufacture.
For example, the number of tapes for attachment to each landing
zone can be varied from one in the case of an infant diaper, to two
or more in the case of an adult brief. Although the illustrated
embodiment has a pair of landing zones 18 in order to minimize the
amount of material needed for strips 20, one elongate landing zone,
extending across the abdominal portion 12a of the backing sheet 12,
could be utilized instead. The thicknesses of the backing sheet and
reinforcing strips are desirably kept at a minimum, but can be
varied. Moreover, the thicknesses of the backing sheet and
reinforcing strips can be identical or different from each other.
The reinforcing strips, although preferably rectangular for
convenience of manufacture, can be provided in other shapes, such
as circular or oval, provided that the adhesive layer has no gaps
permitting ripping of the reinforcement strips or detachment of the
reinforcement strips from the backing layer. Other modifications,
alterations, and changes may be made without departing from the
spirit and scope of the invention as defined in the appended
claims.
* * * * *