U.S. patent application number 14/800822 was filed with the patent office on 2015-11-05 for method for production of disposable absorbent articles.
This patent application is currently assigned to SCA Hygiene Products AB. The applicant listed for this patent is SCA Hygiene Products AB. Invention is credited to Carina HEDLUND, Kent HERMANSSON, Niclas NORRBY, Jan WASTLUND-KARLSSON, Margareta WENNERBACK.
Application Number | 20150313765 14/800822 |
Document ID | / |
Family ID | 36119170 |
Filed Date | 2015-11-05 |
United States Patent
Application |
20150313765 |
Kind Code |
A1 |
HERMANSSON; Kent ; et
al. |
November 5, 2015 |
METHOD FOR PRODUCTION OF DISPOSABLE ABSORBENT ARTICLES
Abstract
A method for production of disposable pant diapers, the method
including providing a length of a substantially homogeneous elastic
laminate web having a maximum elastic extensibility in a first
direction of at least 40% under a peak load F.sub.p; advancing the
length of the substantially homogeneous elastic laminate web in the
first direction; attaching individual absorbent cores to the length
of the elastic laminate web during the advancing to create a strip,
while maintaining the length of the substantially homogeneous
elastic laminate web under a tensioning load F.sub.t in the first
direction; folding the strip onto itself; maintaining the length of
the substantially homogeneous elastic laminate web under the
tensioning load F.sub.t in the first direction during the folding;
the tensioning load F.sub.t satisfying the condition: 0.03
F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p; and welding the
substantially homogeneous elastic laminate web and severing the
individual pant diapers along the weld lines.
Inventors: |
HERMANSSON; Kent; (Vastra
Frolunda, SE) ; WASTLUND-KARLSSON; Jan; (Molndal,
SE) ; WENNERBACK; Margareta; (Molnlycke, SE) ;
HEDLUND; Carina; (Molnlycke, SE) ; NORRBY;
Niclas; (Goteborg, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCA Hygiene Products AB |
Goteborg |
|
SE |
|
|
Assignee: |
SCA Hygiene Products AB
Goteborg
SE
|
Family ID: |
36119170 |
Appl. No.: |
14/800822 |
Filed: |
July 16, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11658539 |
Jan 25, 2007 |
9114041 |
|
|
PCT/SE2004/001384 |
Sep 29, 2004 |
|
|
|
14800822 |
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Current U.S.
Class: |
156/164 |
Current CPC
Class: |
A61F 13/15739 20130101;
A61F 13/15699 20130101; B32B 37/12 20130101; B32B 37/02 20130101;
B32B 38/0012 20130101; B32B 37/22 20130101; B32B 2305/34 20130101;
B32B 2307/726 20130101; A61F 13/15747 20130101; B32B 38/0004
20130101; B32B 2555/02 20130101; Y10T 156/1084 20150115; A61F
13/51401 20130101; B32B 38/1875 20130101; A61F 13/15682 20130101;
A61F 13/51464 20130101 |
International
Class: |
A61F 13/15 20060101
A61F013/15; B32B 38/00 20060101 B32B038/00; B32B 37/22 20060101
B32B037/22 |
Claims
1. A method for production of disposable pant diapers, the method
comprising: providing a continuous length of a substantially
homogeneous elastic laminate web having a maximum elastic
extensibility in a first direction of at least 40% under a peak
load F.sub.p; advancing said continuous length of said
substantially homogeneous elastic laminate web in said first
direction; attaching individual absorbent cores to said continuous
length of said elastic laminate web at spaced intervals during said
advancing to create a strip comprising said continuous length of
said substantially homogeneous elastic laminate web loaded with a
plurality of said cores, while maintaining said continuous length
of said substantially homogeneous elastic laminate web under a
tensioning load F.sub.t in said first direction; folding said strip
onto itself to form a fold edge and an open edge of the pant
diapers; maintaining said continuous length of said substantially
homogeneous elastic laminate web under the tensioning load F.sub.t
in said first direction during said folding; said tensioning load
F.sub.t satisfying the condition: 0.03
F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p; and welding said
substantially homogeneous elastic laminate web to define weld lines
intermittently transverse to the first direction and severing the
individual pant diapers along the weld lines.
2. The method as claimed in claim 1, whereby said tensioning load
F.sub.t satisfies the condition: 0.05
F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p.
3. The method as claimed in claim 1, whereby said tensioning load
F.sub.t satisfies the condition: 0.03
F.sub.p.ltoreq.F.sub.t.ltoreq.0.20 F.sub.p.
4. The method as claimed in claim 1, whereby said tensioning load
F.sub.t satisfies the condition: 0.05
F.sub.p.ltoreq.F.sub.t.ltoreq.0.20 F.sub.p.
5. The method as claimed in claim 1, wherein said substantially
homogeneous elastic laminate web includes a first nonwoven layer
affixed to a first surface of a film layer.
6. The method as claimed in claim 5, wherein said substantially
homogeneous elastic laminate web further comprises a second
nonwoven layer affixed to a second surface of said film layer.
7. The method as claimed in claim 5, wherein said film layer is an
apertured three-layer PE/styrene-based film/PE elastomeric
film.
8. The method as claimed in claim 1, wherein said substantially
homogenous elastic laminate web exhibits a non-linear load-strain
curve relationship which relationship includes a knee point within
the range of 0.03 F.sub.p.ltoreq.F.sub.t.ltoreq.0.20 F.sub.p.
9. The method as claimed in claim 8, wherein the knee point is
located at a position where a load/strain gradient increases
sharply.
10. The method as claimed in claim 5, wherein said first nonwoven
layer is affixed to the first surface of the film layer with
glue.
11. The method as claimed in claim 7, wherein said PE is low
crystallinity polyethylene or metallocene-catalyzed low
crystallinity polyethylene, and/or the styrene-based film is formed
of butadiene-styrene copolymers, styrene block polymers and blends
thereof.
12. The method as claimed in claim 6, wherein said first or said
second nonwoven layer comprises a spunbond or carded material
selected from the group consisting of: polypropylene, polyethylene,
polyester and other polyolefin homopolymers and copolymers.
13. The method as claimed in claim 1, wherein said substantially
homogeneous elastic laminate web constitutes an outer cover of said
pant diaper.
14. The method as claimed in claim 5, wherein said film layer has a
basis weight from about 20 to about 40 g/m.sup.2.
15. The method as claimed in claim 6, wherein each of said first
and said second nonwoven layers has a basis weight of from about 10
g/m.sup.2 to about 40 g/m.sup.2.
16. The method as claimed in claim 6, wherein said first or said
second nonwoven layer has a basis weight of from about 12 g/m.sup.2
to about 30 g/m.sup.2.
17. The method as claimed in claim 6, wherein said first or said
second nonwoven layer has a basis weight of from about 15 g/m.sup.2
to about 25 g/m.sup.2.
18. The method as claimed in claim 16, wherein each of said first
and said second nonwoven layers has a basis weight of from about 12
g/m.sup.2 to about 30 g/m.sup.2.
19. The method as claimed in claim 17, wherein each of said first
and said second nonwoven layers has a basis weight of from about 15
g/m.sup.2 to about 25 g/m.sup.2.
20. The method as claimed in claim 11, wherein said styrene block
polymers comprise styrene/isoprene/styrene (SIS),
styrene/butadiene/styrene (SBS), or
styrene/ethylene-butadiene/styrene (SEBS) block copolymer.
21. The method as claimed in claim 5, wherein said film layer has a
basis weight from about 20 g/m.sup.2 to about 100 g/m.sup.2.
22. The method as claimed in claim 1, wherein said substantially
homogenous elastic laminate web includes two layers having
respective levels of elasticity different from one another.
23. The method as claimed in claim 22, wherein both of said two
layers comprise fibers.
24. The method as claimed in claim 1, wherein said substantially
homogenous elastic laminate web exhibits a non-linear load-strain
curve relationship.
25. A method for production of disposable pant diapers, the method
comprising: providing a continuous length of a substantially
homogeneous elastic laminate web having a maximum elastic
extensibility in a first direction of at least 40% under a peak
load F.sub.p; advancing said continuous length of said
substantially homogeneous elastic laminate web in said first
direction and attaching individual absorbent cores to said
continuous length of said substantially homogeneous elastic
laminate web at spaced intervals, while maintaining said continuous
length of said substantially homogeneous elastic laminate web under
a tensioning load F.sub.t in said first direction during said
advancing; folding said substantially homogeneous elastic laminate
web with the individual absorbent cores attached thereto onto
itself to form a fold edge and an open edge of the pant diapers;
maintaining said continuous length of said substantially
homogeneous elastic laminate web under the tensioning load F.sub.t
in said first direction during said folding, said tensioning load
F.sub.t satisfying the condition: 0.03
F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p, and welding said
substantially homogeneous elastic laminate web to define weld lines
intermittently transverse to the first direction and severing the
individual pant diapers along the weld lines.
26. The method as claimed in claim 25, whereby said tensioning load
F.sub.t satisfies the condition: 0.05
F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p.
27. The method as claimed in claim 25, wherein said substantially
homogeneous elastic laminate web includes a first nonwoven layer
affixed to a first surface of a film layer.
28. The method as claimed in claim 27, wherein said substantially
homogeneous elastic laminate web further comprises a second
nonwoven layer affixed to a second surface of said film layer.
29. The method as claimed in claim 27, wherein said film layer is
an apertured three-layer PE/styrene-based film/PE elastomeric
film.
30. The method as claimed in claim 25, wherein the substantially
homogenous elastic laminate webs each includes two layers having
respective levels of elasticity different from one another.
31. The method as claimed in claim 25, wherein said substantially
homogenous elastic laminate web exhibits a non-linear load-strain
curve relationship.
32. A method for production of disposable hygienic absorbent
articles, the method comprising: advancing, in a first direction,
first and second continuous lengths of a substantially homogeneous
elastic laminate web having a maximum elastic extensibility in the
first direction of at least 40% under a peak load F.sub.p; said
first and second continuous lengths being spaced apart in a second
direction orthogonal to the first direction; maintaining said first
and second continuous lengths of the substantially homogeneous
elastic laminate web under a tensioning load F.sub.t in the first
direction during the advancing, the tensioning load F.sub.t
satisfying the condition: 0.03 F.sub.p.ltoreq.F.sub.t.ltoreq.0.25
F.sub.p; joining the spaced apart first and second continuous
lengths to a non-elastic nonwoven material to thereby define the
outer cover of a diaper in which the first and second continuous
lengths are respectively located in the front and rear of the
diaper, and in which the non-elastic nonwoven material is located
in the crotch of the diaper.
33. The method as claimed in claim 32, wherein said non-elastic
nonwoven material is a strip of non-elastic nonwoven material.
34. The method as claimed in claim 32, wherein: said substantially
homogenous elastic laminate webs each includes two layers having
respective levels of elasticity different from one another, and
each of said substantially homogenous elastic laminate webs
exhibits a non-linear load-strain curve relationship.
35. The method as claimed in claim 32, further comprising the step
of attaching individual absorbent cores to said non-elastic
nonwoven material.
36. The method as claimed in claim 32, further comprising: folding
one of the first and second continuous lengths of substantially
homogeneous elastic laminate web onto the other of the first and
second continuous lengths of substantially homogeneous elastic
laminate web to form a fold edge and an open edge of the disposable
hygienic absorbent articles; welding said substantially homogeneous
elastic laminate webs together to define weld lines intermittently
transverse to the first direction; and severing the substantially
homogeneous elastic laminate webs along the weld lines to form
individual disposable hygienic absorbent articles.
37. The method as claimed in claim 36, further comprising: folding
one of the first and second continuous lengths of substantially
homogeneous elastic laminate web onto the other of the first and
second continuous lengths of substantially homogeneous elastic
laminate web to form a fold edge and an open edge of the disposable
hygienic absorbent articles; welding said substantially homogeneous
elastic laminate webs together to define weld lines intermittently
transverse to the first direction; and severing the substantially
homogeneous elastic laminate webs along the weld lines to form
individual disposable hygienic absorbent articles.
Description
[0001] The present application is a continuation of U.S. Ser. No.
11/658,539, filed on Jan. 25, 2007, which is a national stage
application of PCT/SE2004/001384, filed on Sep. 29, 2004. The
entire contents of U.S. Ser. No. 11/658,539 and PCT/SE2004/001384
are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a method for production of
disposable hygienic absorbent articles such as pants-type absorbent
articles.
BACKGROUND OF THE INVENTION
[0003] In order to improve comfort and fit, disposable hygienic
articles, and particularly those which are intended to be worn
around the waist of a user, are commonly provided with elastic
components in selected regions of the article. In a pants-type
absorbent article, i.e. an article which is pulled on in the same
manner as a traditional pair of pants, the selected regions
comprise the waist opening and the leg openings. Conventionally,
the elastic components used in these regions are in the form of
elastic threads or bands which are secured to a substrate, e.g. the
outer cover of the article, in a stretched state under a tensioning
force. When the tensioning force is released, the elastic
components contract and thereby gather the substrate to which they
are secured. In this manner, an otherwise substantially inelastic
material web can be provided with elastic properties.
[0004] The above-described manner of providing elasticised regions
on an absorbent article suffers from several drawbacks. For
example, securing the elastic components to a running material web
in a continuous process is relatively complicated. The elastic
components are generally secured to the material web with adhesive,
for example hot-melt adhesive or thermosetting adhesive. To ensure
that the elastic components do not release from the material web
during the production process, it is necessary to ensure that the
elastic components bear against the material web until the adhesive
has set, dried or hardened. Problems may also arise in
synchronizing the tensioning of the different elastic components
and in achieving uniform tensioning of the different elastic
components independently of the speed of the running web material.
Since the extent of elasticity of the thus elasticised material web
is directly proportional to the degree to which the elastic
components are tensioned, typically 100%, when attached to the
material web, during production the articles occupy an area which
is substantially greater than that occupied by the finished
articles in a relaxed state. This implies that the production
facility takes up an undesirably large area. In addition, the
production equipment has to be dimensioned to accommodate the
tensioning force. A further difficulty is that of handling the
finished articles once they have been severed from the running
material web, since the articles assume an irregular
three-dimensional shape as soon as the tensioning of the elastic
components ceases. Folding and packaging of the finished articles
have additionally proven to be very difficult steps because of
their creased and three-dimensional shape.
[0005] Although such elasticised disposable absorbent articles may
provide satisfactory comfort and fit, the thus gathered material
web can impart a bulky, creased appearance to the article. This
implies that it may be difficult to conceal the article under
normal clothing. This is particularly problematic for adult users
of disposable absorbent pants.
[0006] To overcome at least some of these drawbacks, rather than
using an elasticised material in disposable absorbent articles, it
has been proposed to make at least some regions of disposable
absorbent articles of elastic material per se, for example an
elastic nonwoven or elastic laminate. By using such material, there
is no need to secure a tensioned elastic component to a gatherable
substrate. As such, theoretically at least, it is possible to
manufacture disposable absorbent articles in a process in which the
constituent elastic components are substantially unstretched.
Indeed, in WO-A-03/070140 it is proposed to stretch the elastic
material web during production to a maximum of 5%.
[0007] The present inventors have found that, in order to ensure
accurate control of the elastic material web during production, it
is necessary to subject the web to a certain minimum tensioning
load. On the other hand, to enjoy as many as possible of the
advantages that, at least theoretically, are available using an
elastic material web vis-a-vis an elasticised web, it is important
that the tensioning load be significantly less than the load to
attain maximum elastic extensibility of the elastic material
web.
OBJECTS AND SUMMARY
[0008] It is therefore an object of the invention to provide a
method of production of disposable hygienic absorbent articles
which permits efficient production of the articles.
[0009] According to one method, a disposable hygienic absorbent
article is produced in a process in which an elastic material web
is a substantially homogenous elastic laminate web having a maximum
elastic extensibility in a first direction of at least 40%,
preferably at least 60%, and most preferably at least 80%, under a
peak load F.sub.p. The elastic laminate web is advanced in a
direction of travel corresponding to the first direction while
being maintained under a tensioning load F.sub.t satisfying the
condition: 0.03 F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p.
[0010] For the purposes of this disclosure, an elastic laminate web
is to be regarded as substantially homogenous if the properties of
the web at any two sections of the web are essentially the same in
the same direction.
[0011] Elastic extensibility here refers to the lengthening of the
elastic laminate web in the direction of applied load which the web
permits without plastically deforming or rupturing. For a material
to be deemed to be elastically extensible it must also strive to
recover its original length once the tensioning load is removed.
For present purposes, a laminate web is deemed to be elastically
extensible if it can be extended in at least one direction to at
least 130% of its initial length, and will revert to at most 120%,
preferably no more than 110%, of its original length upon removal
of the tensioning load, while still meeting the requirement of
maximum elastic extensibility outlined above.
[0012] Due to the non-linear load/elongation property of elastic
laminate webs caused by the inter-engagement of fibres of the less
elastic layer or layers of the laminate, the %-elongation per unit
load decreases at higher values of elongation. By selecting the
tensioning load F.sub.t so as to satisfy the condition 0.03
F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p, adequate extension of
the web is assured at the same time that the production equipment
is not subjected to unnecessarily large forces.
[0013] Under certain circumstances, it may be preferable to
increase the elongation of the laminate during production. As such,
in a preferred embodiment, the tensioning load F.sub.t may be
selected so as to satisfy the condition 0.05
F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p. Similarly, where it is
desirable to keep the load on the laminate as low as possible,
F.sub.t may be selected so as to satisfy the condition 0.03
F.sub.p.ltoreq.F.sub.t.ltoreq.0.20 F.sub.p. In a further preferred
embodiment, F.sub.t may be selected so as to satisfy the condition
0.05 F.sub.p.ltoreq.F.sub.t.ltoreq.0.20 F.sub.p.
[0014] Preferably, the elastic laminate web comprises at least one
nonwoven layer affixed to a film layer. The film layer is
preferably an apertured three-layer PE/styrene-based film/PE
elastomeric film.
BRIEF DESCRIPTION OF DRAWINGS
[0015] Embodiments of the invention will be described in the
following in greater detail by way of example only and with
reference to the attached drawings, in which:
[0016] FIG. 1 is a schematic perspective view of a length of a
production line for the production of a disposable hygienic
absorbent article in accordance with an embodiment of the present
invention;
[0017] FIG. 2 is a schematic graphic representation showing load
vs. strain for an elastic laminate;
[0018] FIG. 3 is a graph showing load vs. strain for an elastic
laminate comprising 25 gsm nonwoven material;
[0019] FIG. 4 is a graph showing load vs. strain for an elastic
laminate comprising 20 gsm nonwoven material;
[0020] FIG. 5 is a graph showing load vs. strain for an elastic
laminate comprising 18 gsm nonwoven material, and
[0021] FIG. 6 is a cross-sectional view through an elastic laminate
web for use in an embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] In FIG. 1, reference numeral 10 generally denotes length of
a production line for the production of a disposable hygienic
absorbent article 12. In the present example, the absorbent article
is a pull-up pants-type diaper.
[0023] The various components of the absorbent article are united
on a (not shown) continuous conveyor belt running in a direction of
travel denoted by arrow A. In the broadest form of the invention, a
continuous length of a substantially homogenous elastic laminate
web 14 is placed on the conveyor belt and maintained under a
tensioning load F.sub.t. The elastic laminate web has a maximum
extensibility in a first direction corresponding to the direction
of travel denoted by arrow A of at least 40%, preferably at least
60%, and most preferably at least 80%, under a peak load F.sub.p.
The continuous length of the elastic laminate web 14 is advanced in
the direction of travel A to a station at which individual
absorbent cores 16 are attached to the continuous length of the
elastic laminate web 14 at spaced intervals. Individual articles
12, in this case pull-up pants-type diapers, are thereafter formed
from the thus assembled individual absorbent cores 16 and the
continuous length of the elastic laminate web.
[0024] The continuous length of the elastic laminate web 14 is
maintained under a tensioning load F.sub.t in the direction of
travel during the advancing, with the tensioning load F.sub.t
satisfying the condition: 0.03 F.sub.p.ltoreq.F.sub.t.ltoreq.0.25
F.sub.p.
[0025] In order to carry out the above described method, it is
necessary to determine the peak load F.sub.p, i.e. the load under
which the elastic laminate web displays elastic extensibility. The
peak load is determined using the ASTM D 882 tensile strength test
method. The tensile strength and elongation of a well-defined test
piece is tested by means of a tensile tester.
Apparatus: Instron 4301
[0026] Tensile tester connected to a computer Crosshead speed: 500
mm/min Clamp distance: 50 mm
[0027] Sample preparation: Test samples are cut from the entire
width of the material. The width of the sample shall be 25.4 mm and
the length at least 50 mm longer than the clamp distance if
possible. It is of importance that the edges of the sample are even
and without break notches. The samples are conditioned for at least
4 h in 50% RH.+-.5% RH and 23.degree. C..+-.2.degree. C. before
testing.
[0028] Procedure: The tensile tester is calibrated according to the
apparatus instructions and set to zero. The sample is mounted and
it is ensured that it is not obliquely or unevenly fastened. The
material is prevented from slipping by using clamps covered with
galloon or similar material. The tensile tester is started, and
stopped after the material has broken (if not automatically
controlled). Measurements resulting from premature failures (i.e.
the sample breaks at the clamp, or is damaged during preparation)
are ignored if possible.
[0029] The following results are expressed by the tensile
tester/computer:
Maximum force, N/25.4 mm Elongation at maximum force, % Break
force, N/25.4 mm Elongation at break force, Knee point, N/%
[0030] FIG. 2 is a schematic representation of the behaviour of an
elastic laminate web for use in the method according to the present
invention under stretching at a constant strain. The laminate web
comprises 25 gsm Sofspan NW from BBA on both sides of a 40 gsm
apertured elastic film, where one face is glue-laminated with
approximately 5 gsm glue.
[0031] From zero strain, the elastic laminate web exhibits
substantially elastic behaviour in region (A) up to around a "knee
point" (B), after which, the load increases rapidly through region
(C). The knee point (B) is defined as the first point on the
load-strain curve at which the gradient becomes greater than
0.3N/%. The laminate web shown is elastic up to about 80% strain.
The applied load eventually reaches a maximum (the "peak load") at
point (D), at which the gradient of the load-strain curve is zero.
The load then drops through region (E) as the material fails.
Complete failure of the laminate web occurs at point (F).
[0032] The peak load F.sub.p is the applied load at point D. In the
embodiment of the present invention, the elastic laminate web is
maintained under a tensioning load F.sub.t which satisfies the
condition: 0.03 F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p.
[0033] FIGS. 3 to 5 show the actual behaviour of elastic laminate
webs having a 40 gsm apertured elastic film, though glue-laminated
with approximately 3 gsm glue to Sofspan NW of different basis
weights. Thus, in FIG. 3 the basis weight of the nowwoven webs is
25 gsm, in FIG. 4 it is 20 gsm and in FIG. 5 it is 18 gsm. In all
cases, the "knee point" (B) lies within the range 0.03
F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p.
[0034] Under certain circumstances, it may be preferable to
increase the elongation of the laminate during production. As such,
in a preferred embodiment, the tensioning load F.sub.t may be
selected so as to satisfy the condition 0.05
F.sub.p.ltoreq.F.sub.t.ltoreq.0.25 F.sub.p. Similarly, where it is
desirable to keep the load on the laminate as low as possible,
F.sub.t may be selected so as to satisfy the condition 0.03
F.sub.p.ltoreq.F.sub.t.ltoreq.0.20 F.sub.p. In a further preferred
embodiment, F.sub.t may be selected so as to satisfy the condition
0.05 F.sub.p.ltoreq.F.sub.t.ltoreq.0.20 F.sub.p.
[0035] FIG. 6 is a cross-section through an elastic laminate web 14
for use in an embodiment of the present invention. The elastic
laminate web comprises a first nonwoven layer 26 affixed to a first
surface 28 of a film layer 30. Advantageously, the elastic laminate
web further comprises a second nonwoven layer 32 affixed to a
second surface 34 of the film layer 30.
[0036] Preferably, the film layer comprises an elastic film having
a basis weight from about 20 g/m.sup.2 to about 100 g/m.sup.2,
preferably between 20 and 60 g/m.sup.2. The film layer may be
selected from the group consisting of low crystallinity
polyethylenes, metallocene-catalyzed low crystallinity
polyethylene, ethylene vinyl acetate copolymers (EVA),
polyurethane, polyisoprene, butadiene-styrene copolymers, styrene
block polymers such as styrene/isoprene/styrene (SIS),
styrene/butadiene/styrene (SBS), styrene/ethylene-butadiene/styrene
(SEBS) block copolymer and blends thereof.
[0037] To increase the breathability of the elastic laminate web,
the film layer 30 may be provided with apertures 37. In a preferred
embodiment, the film is an apertured three-layer PE/styrene-based
film/PE elastomeric film.
[0038] Each of the first and second nonwoven layers may have a
basis weight of from about 10 g/m.sup.2 to about 40 g/m.sup.2,
preferably from about 12 g/m.sup.2 to about 30 g/m.sup.2, most
preferably from about 15 g/m.sup.2 to about 25 g/m.sup.2, and may
comprise a spunbond or carded material selected from the group
consisting of: polypropylene, polyethylene, polyester and other
polyolefin homopolymers and copolymers.
[0039] In order to provide the individual articles 12 with
desirable properties, the basic production method outlined above
may be complemented by one or more of the following steps.
[0040] In the production of a pants-type diaper, adhesive 36 may be
applied, for example by spraying or coating, to the elastic
laminate web 14, after which elastic members 38 in the form of
continuous elastic bands or threads are secured in a curved pattern
across the laminate web. These elastic members 38 will form
elasticised leg openings in the completed article 12.
Alternatively, the adhesive may be applied directly to the elastic
members themselves.
[0041] A second material web 40 of liquid barrier material, such as
an elastic plastic film, may thereafter be applied over the elastic
laminate web 14 and the elastic members 38. The second material web
may be provided with adhesive on its surface facing the first web
14 to ensure its adequate adhesion thereto.
[0042] In the illustrated embodiment a third material web 42 is
placed over the elastic laminate web 14 and the second material web
40 and secured over the absorbent cores 16. The third elastic
material web will constitute the topsheet of the completed
absorbent article. As such, it can consist of a nonwoven material,
e g spunbond, meltblown, carded, hydroentangled, wetlaid etc.
Suitable nonwoven materials can be composed of natural fibers, such
as woodpulp or cotton fibres, manmade fibres, such as polyester,
polyethylene, polypropylene, viscose etc. or from a mixture of
natural and manmade fibres. The topsheet material may further be
composed of tow fibres, which may be bonded to each other in a
bonding pattern, as e.g. disclosed in EP-A-1 035 818. Further
examples of topsheet materials are porous foams, apertured plastic
films etc. The materials suited as topsheet materials should be
soft and non-irritating to the skin and intended to be readily
penetrated by body fluid, e.g. urine or menstrual fluid.
Advantageously, the third material web will have elastic
properties. Before the third material web is applied to the second
material web, the third elastic web may be coated with an adhesive
on its surface directed towards the second material web.
[0043] In an alternative production method, the second material web
40 of liquid barrier material may be omitted. Instead, nonwoven
material may be placed over the elastic members 38. Liquid barrier
material may then be incorporated in an absorbent packet comprising
a plastic film, an absorbent core and a nonwoven surface layer.
Although in FIG. 1 the elastic members 38 as laid out on the
elastic laminate web comprise crotch elastic, it is to be
understood that the crotch elastic may be incorporated in the
thus-described absorbent packet instead.
[0044] The above-described assembly of components forms a
production web 44. Leg openings 46 are cut out from the production
web and the production web is then folded double in the production
direction so that a fold edge 48 and an open edge 50 are formed.
The folded production web 44 is then welded intermittently
transverse to the production direction along weld lines 52
extending from the open edge 50 to the edge at each leg opening 46.
The welded production web 44 is then divided by being severed along
each weld line 52 so that individual pants-type diapers 12 are
separated from the production web 44. The individual diapers can
then be subjected to further processing steps such as folding and
packing.
[0045] The elastic laminate web 14 of the thus-produced pants-type
diapers 12 constitutes the outer cover of the diapers. In a similar
manner, the elastic laminate web may also constitute the outer
cover of many types of disposable hygienic absorbent articles, such
as conventional diapers, incontinence garments, sanitary napkins
and panty liners. It is to be understood that the elastic laminate
web 14 need not cover the entire outer surface of such articles.
Instead, in certain circumstances it may be desirable to have a
non-elastic region of the outer cover. Thus, for example, the
crotch region of a diaper may have an outer cover region which is
constituted by a strip of non-elastic nonwoven material bounded on
either side by an elastic laminate web. In this manner, front and
rear panels of the diaper will enjoy elastic properties.
* * * * *