U.S. patent application number 10/220531 was filed with the patent office on 2003-05-15 for single-use absorbent sanitary article.
Invention is credited to Malowaniec, Krzysztof D., Mangold, Rainer, Wurster, Thomas.
Application Number | 20030093051 10/220531 |
Document ID | / |
Family ID | 26004652 |
Filed Date | 2003-05-15 |
United States Patent
Application |
20030093051 |
Kind Code |
A1 |
Malowaniec, Krzysztof D. ;
et al. |
May 15, 2003 |
Single-use absorbent sanitary article
Abstract
The invention relates to a single-use absorbent sanitary
article, especially diapers, sanitary napkins, and incontinence
articles. The inventive sanitary article comprises an absorbent
body (30) that consists of at least two layers, one layer (32) for
absorbing, distributing and temporarily storing liquid and facing
the body when used, and one storage layer (34) on the side facing
away from the body which has a content of at least 50% of
superabsorbent polymer material. The inventive layer (32) for
absorbing, distributing and temporarily storing liquid is extruded
from a thermoplastic polymer to which a blowing agent is added.
Inventors: |
Malowaniec, Krzysztof D.;
(Heidenheim, DE) ; Mangold, Rainer;
(Herbrechtingen, DE) ; Wurster, Thomas;
(Heidenheim, DE) |
Correspondence
Address: |
William M Halon Jr
Young & Basile
Suite 624
3001 West Big Beaver Road
Troy
MI
48084
US
|
Family ID: |
26004652 |
Appl. No.: |
10/220531 |
Filed: |
August 29, 2002 |
PCT Filed: |
March 2, 2001 |
PCT NO: |
PCT/EP01/02386 |
Current U.S.
Class: |
604/378 ;
604/368; 604/369; 604/370 |
Current CPC
Class: |
A61F 13/15617 20130101;
A61F 2013/530948 20130101; A61F 13/53 20130101; A61L 15/425
20130101; A61F 13/47227 20130101; A61L 15/60 20130101; Y10T
428/24405 20150115; Y10T 428/2457 20150115; A61F 2013/1543
20130101; A61F 13/534 20130101; A61F 13/535 20130101; A61L 15/225
20130101; Y10T 428/24479 20150115; A61F 13/53747 20130101; A61F
13/532 20130101 |
Class at
Publication: |
604/378 ;
604/370; 604/368; 604/369 |
International
Class: |
A61F 013/15; A61F
013/20 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 2, 2000 |
DE |
100 10 269.7 |
Mar 2, 2000 |
DE |
100 10 268.9 |
Claims
What is claimed is:
1. Absorbent sanitary article for one-time use, specifically
diaper, feminine napkin, incontinence pad, having an at least
two-ply absorbent body (30) which comprises a layer for absorbing,
distributing and temporarily storing fluid (32) contacting the body
when the article is used and a storage layer (34) furnished on the
side away from the body having a content of at least 50% by weight
of superabsorbent polymer materials, characterized in that the
layer for absorbing, distributing and temporarily storing fluid
(32) is extruded from a thermoplastic polymer with the addition of
a blowing agent.
2. Sanitary article from claim 1, wherein the layer for absorbing,
distributing and temporarily storing fluid (32) has a total pore
volume of at least 30 ml.
3. Sanitary article from one of the preceding claims, wherein the
layer for absorbing, distributing and temporarily storing fluid
(32) is essentially free from superabsorbent polymer materials.
4. Sanitary article from one of the claims 1, 2 or 3, wherein the
thermoplastic polymer comprises a polyolefin, specifically
polypropylene and/or polyethylene.
5. Sanitary article from one or more of the preceding claims,
wherein the degree of foaming is greater than 50%.
6. Sanitary article from one or more of the preceding claims,
wherein the degree of foaming is greater than 100%.
7. Sanitary article from one or more of the preceding claims,
wherein the layer for absorbing, distributing and temporarily
storing fluid (32) comprises 3%-30% by weight, specifically 10%-20%
by weight fibers as additive materials.
8. Sanitary article from claim 7, wherein the fibers are formed
from polyester fibers.
9. Sanitary article from one or more of the preceding claims,
wherein the unit weight of the layer for absorbing, distributing
and temporarily storing fluid (32) varies in the longitudinal
and/or perpendicular direction.
10. Sanitary article from one or more of the preceding claims,
wherein the width of the layer for absorbing, distributing and
temporarily storing fluid (32) varies over its longitudinal
direction.
11. Sanitary article from one or more of the preceding claims,
wherein a storage layer (34) is furnished on the side of the layer
for absorbing, distributing and temporarily storing fluid (32)
facing away from the body when in use and is extruded with said
layer.
12. Process for producing a layer for absorbing, distributing and
temporarily storing fluid (32) as part of producing a sanitary
article from one or more of the preceding claims 1-11, comprising
the following steps: introduction of a thermoplastic polymer into
an extrusion apparatus, melting the thermoplastic polymer material,
introduction of a blowing agent under positive pressure, extrusion
of the mixture, where the blowing agent results in foaming of the
thermoplastic polymer when pressure is reduced.
13. Process from claim 12, wherein CO.sub.2 is used as the blowing
agent.
14. Process from claim 12 or 13, wherein the thermoplastic polymer
is melted at temperatures of 80-200 degrees C.
15. Process from claim 12, 13 or 14, wherein fibers are introduced
into the extrusion apparatus as an additive.
16. Process from one of the claims 12-16, wherein a surfactant
substance is introduced into the extrusion apparatus as an
additive.
17. Process from one of the claims 12-16, wherein an extrusion
cross-section is changed during extrusion.
18. Process from claim 17, wherein the extrusion cross-section is
changed in an oscillating manner.
19. Process from claim 12-18, wherein the process is integrated
into a production process for sanitary articles and thereby the
layer for absorbing, distributing and temporarily storing fluid
(32) is extruded directly inside high-speed production machinery
for sanitary articles.
20. Process from claim 19, wherein the layer for absorbing,
distributing and temporarily storing fluid (32) and the storage
layer are formed inside the high-production machinery by
co-extrusion of the layers.
Description
BACKGROUND
[0001] The invention relates to a single-use absorbent sanitary
article, specifically a diaper, women's sanitary napkin or
incontinence article, having an at least double-layer absorbent
body which includes a layer contacting the body in use for
absorbing, distributing and temporarily storing fluid and a storage
layer furnished on the side facing away from the body having a
content of at least 50% by weight of superabsorbent polymer
materials.
[0002] The invention further relates to a process for producing a
layer for absorbing, distributing and temporarily storing fluid in
the course of producing a sanitary article of the said type.
[0003] Large numbers of sanitary articles of this kind are known.
In generic sanitary articles, the high superabsorbent polymer
materials content in the storage layer facing away from the body in
use serves to permanently store the absorbed fluid because the
superabsorbent polymer materials bind aqueous fluid and are
converted into a gel-like state. Since the time required for this
compared with the discharge time for the fluid during passing of
water by the wearer of the sanitary article is relatively long, a
layer for absorbing, distributing and temporarily storing fluid is
provided in a known way, arranged on the side of the storage layer
contacting the body. The task of this layer for absorbing,
distributing and temporarily storing fluid is to provide an
adequately high absorption rate for the flood of impacting fluid to
prevent it from running across the sanitary article in the
transverse or longitudinal direction, which would detract from its
functionality. Furthermore, the layer for absorbing, distributing
and temporarily storing fluid is intended to channel the relatively
concentrated contacting fluid into other areas of the absorbent
body in order to be able to utilize the fluid absorption capacity
available there. The aim is then to distribute fluid within the
distribution layer contacting the body, but also to temporarily
store and subsequently discharge fluid to the storage layer located
thereunder.
[0004] Efforts have already been made to use materials for the
layer for absorbing, distributing and temporarily storing fluid
which, even with wetting, and specifically repeated wetting, can
perform the previously named function for the layer contacting the
body at least largely unimpaired by the wetting. Preferably
entangled cellulose fibers, which are also described as "curled
fibers," are used in the distribution layer contacting the body. A
distribution layer consisting of entangled cellulose fibers or
comprising such fibers to a substantial degree, which is disposed
on the side of the storage layer contacting the body, retains a
relatively large fluid retention volume even after saturation and
does not collapse on itself ("wet collapse") in contrast to a layer
formed from natural non-entangled cellulose fibers.
[0005] With this as the point of departure, the object of the
present invention is to improve an absorbent sanitary article of
the generic type such that its layer for absorbing, distributing
and temporarily storing fluid has fluid absorbency, distribution
and temporary storage characteristics at least as good as the
previously named sanitary article, even without substantial content
of entangled cellulose fibers.
SUMMARY
[0006] This object is accomplished in the case of a generic
sanitary article of the invention by extruding the layer for
absorbing, distributing and temporarily storing fluid from a
thermoplastic polymer with the addition of a blowing agent.
[0007] It was shown that impinging aqueous fluid can penetrate very
rapidly into the open-pored foamed structure formed by extrusion as
a blowing agent expands and be stored there temporarily.
Corresponding to the degree of foaming, which is preferably greater
than 50% and in an especially preferred manner greater than 100%,
the extruded layer makes available a measured take-up volume of
preferably more than 30 ml, even following specifically repeated
heavy fluid contact while the sanitary article is in use.
[0008] In the case of the layer for absorbing, distributing and
temporarily storing fluid extruded in the manner described, the
problems discussed above concerning collapse of a fiber structure
when saturated does not occur. Following heavy impaction of fluid,
the fluid is temporarily stored in the pores and gradually
discharged to the storage layer disposed thereunder, where the
fluid is then permanently stored by means of the superabsorbent
polymer materials there provided.
[0009] The layer for absorbing, distributing and temporarily
storing fluid is preferably substantially free of superabsorbent
polymer materials, by which it should be understood that it has
preferably less than 10%, specifically less than 5% by weight and
especially preferably less than 1% by weight of superabsorbent
polymer materials.
[0010] A polymer from the group of polyolefins, specifically
polypropylenes and/or polyethylenes, has proven suitable as a
thermoplastic polymer in an especially preferred fashion.
Corresponding co-polymers, specifically ethylene vinyl acetate
copolymers as well as halogenated polyolefins, can also be used.
However, other thermoplastic polymers are suitable in principle for
the production of the inventive absorbent structure, e.g., those
from the group of the styrene polymers.
[0011] Additives, for example 3% to 30% by weight, specifically 10%
to 20% by weight, in the form of fibers, preferably polyester
fibers, can also be provided. By adding fibers whose melting or
degradation temperature is higher than the melting temperature of
the thermoplastic polymers used, passages are formed during the
extrusion process which promote the penetration and distribution of
aqueous fluid into the structure and within the structure as well
as the transfer of the fluid to the storage layer disposed
thereunder.
[0012] The invention makes it possible in a particularly
advantageous way for the mass per unit area, i.e., the thickness of
the layer for absorbing, distributing and temporarily storing
fluid, to be varied in the longitudinal and/or in the transverse
direction, where the longitudinal direction by definition should
coincide with the direction of extrusion. By suitably shaping an
extrusion opening, specifically an extrusion die, structures having
any type of cross-section can be achieved. The thickness of the
absorbent structure, specifically viewed in cross-section
perpendicular to the longitudinal direction, could be thicker in
the center and in conformity with the structure of the extrusion
opening decrease toward the sides in any fashion desired.
[0013] In the same way it can prove to be advantageous if the width
of the extruded layer varies in the longitudinal direction; layers
which are profiled in plan view, for example, an hour glass shape,
can be created in this way.
[0014] The layer for absorbing, distributing and temporarily
storing fluid can additionally comprise a surfactant substance,
specifically a hydrophilizing agent in an amount of preferably 0.2%
to 10% by weight. The already extruded structure can be contacted
secondarily with the hydrophilizing agent. In a preferred manner,
this agent is fed to an extrusion apparatus jointly with the
remaining initial materials or injected into the already molten
polymer mass, so it is already in mixture with the polymer melt
before said melt is extruded. Advantageously alkyl sulfonates,
fatty acid derivates and fluorochemicals are used for this--as
described in the publication "Polymer Melt Additives; Their
Chemistry, Structure and Use" (authors Gasper et al., lecture
during Insight 1999 "Non-wovens Business/Fiber and Fabric
Conferences," San Diego, Calif., Nov. 1-2, 1999, Proceeding
published by Marketing Technology Services, Inc.).
[0015] To increase the accessibility of the extruded structure for
aqueous fluids, it is advantageous to subject the extruded
structure to further mechanical treatment, for example, stretching,
compression (rolling) and/or perforation by a fine needling tool. A
possibly closed pore can thereby come into fluid communication with
other pores and contribute to the take-up capacity, also to the
distribution and transfer function, or be activated,
respectively.
[0016] Multi-stage rolling of the extruded structure is
particularly advantageous. Multi-stage rolling makes it possible to
apply several temperature and/or pressure stages. The extruded
structure can thereby can be altered/optimized more selectively
with respect to the requirements of its later use. Thus it has
proven to be advantageous to compress the extruded structure in a
first calendering stage at a temperature that is appropriate for
keeping the thermoplastic polymer in the extruded structure above
the softening temperature. Depending on the polymer used, a
temperature of 40.degree.-90.degree. C., specifically
45.degree.-70.degree. C., specifically 50.degree.-60.degree. C.,
has proven to be suitable. Afterwards the extruded absorbent
structure can be advantageously compressed cold in a second
calendering stage, which is performed specifically at temperatures
of 0.degree. C.-30.degree. C., specifically at 15.degree.
C.-25.degree. C.
[0017] It has furthermore proved to be advantageous to subject the
extruded structure to additional stretching.
[0018] It is also conceivable that the storage layer is similarly
produced as an extruded foamed structure. In such cases, granular
particles of superabsorbent materials are introduced into an
extrusion apparatus together with thermoplastic polymer, and the
thermoplastic polymer materials are melted at temperatures below
the degradation temperature of the superabsorbent polymer materials
and extruded with said such materials. In such cases, both the
layer for absorbing, distributing and temporarily storing fluid as
well as the storage layer could be produced inside the production
machinery by direct co-extrusion.
[0019] A fluid-impermeable film layer disposed on the side of the
storage layer facing away from the body can be produced by
co-extrusion with the preceding layers. A fixing agent, such as a
hot-melt adhesive, can then be advantageously dispensed with, since
the extruded layers can be fixated with each other; but also with
respect to additional layers and/or elements of the sanitary
article by extrusion during the course of production.
[0020] In an advantageous improvement of the invention, it is also
conceivable that the layer for absorbing, distributing and
temporarily storing fluid has wall sections on both sides extending
upwardly in the longitudinal direction of the sanitary article and
toward the wearer, which form a leakage barrier. These wall
sections then assume the function of gatherings which are usually
formed in known sanitary articles from non-woven materials with
inserted means of elastification.
[0021] Also subject of the present invention is also a process for
producing a layer for absorbing, distributing and temporarily
storing fluid as part of production of a sanitary article.
[0022] CO.sub.2 is preferably used as the blowing agent, although
equally conceivable would be saturated, unsaturated, cyclic
hydrocarbons and halogenated hydrocarbons as well as noble gases,
such as argon, helium or nitrogen, or a water/air mixture or water
itself, preferably in the form of moisture which is part of or in
the extruded materials.
[0023] Inside the extrusion apparatus positive pressure is
preferably developed high enough that the blowing agent finds
itself in a so-called "supercritical state", in which the phase
boundary between fluid and gaseous aggregate state disappears and
only a single homogenous phase is present. In the case of CO.sub.2,
this state is present at temperatures above about 31.degree. C. and
pressures above 73.5 bar. In this state, the blowing agent can be
mixed optimally for preparing a physical foaming process with the
molten thermoplastic polymer. If this mixture is then passed
through an extrusion opening into an area of lower pressure, the
blowing agent evaporates with decreasing temperature, and the
foamed open-pore structure of the layer for absorbing, distributing
and temporarily storing fluid is created.
[0024] But since not only does the blowing agent have to attain a
preferably supercritical state, the thermoplastic polymer must be
at least partially melted, temperatures of 80.degree. C. to
200.degree. C. are generated inside the extrusion apparatus.
[0025] To produce a large number of similarly configured
structures, it proves to be advantageous if the extrusion
cross-section is changed in a correspondingly oscillating fashion.
This takes place transversely to the direction of extrusion,
specifically in the discharge direction, whereby the thickness of
an extruded web is varied, or transversely to the discharge
direction, whereby its width is varied.
[0026] It proves to quite particularly advantageous if the
extrusion process is directly integrated into the production
process for the sanitary article and thereby the layer for
absorbing, distributing and temporarily storing fluid is extruded
directly inside a high-speed machine for producing sanitary
articles.
BRIEF DESCRIPTION OF THE DRAWING
[0027] Additional details, features and advantages of the invention
can be found in the appended patent claims and from the drawings
and the description which follows of an inventive sanitary article.
In the drawings:
[0028] FIG. 1 shows a schematic view of an apparatus for producing
a layer for absorbing, distributing and temporarily storing fluid
for an inventive sanitary article;
[0029] FIGS. 2 and 3 show a top view and a sectional view through
an absorbent body of an inventive sanitary article, respectively;
and
[0030] FIG. 4 shows a top view corresponding to FIG. 2 of an
absorbent body with a width varying in the longitudinal
direction.
DETAILED DESCRIPTION
[0031] FIG. 1 shows an apparatus for extruding a layer for
absorbing, distributing and temporarily storing fluid. The
apparatus includes a funnel-shaped feed device 1, through which a
solid-material mixture, which was preferably produced previously in
accordance with the composition by weight percentage of the
individual ingredients, can be introduced into a cylindrical
interior 4 of a high-pressure stable tubular housing 5 of the
extrusion device. A shaft 6 extends in this interior 4 having a
helical screw 8 driven by an electric motor. When the shaft 6 is
driven, the solid-matter mixture which was introduced is further
mixed and transported in longitudinal direction 10. Heating devices
12 are provided on the outer circumference of the tubular housing
5.
[0032] An extrusion tool 16 can be mounted on the end face of the
tubular housing 5 at the end opposite the feed device 2. The
extrusion tool 16 communicates through an opening 18 on the end
face 14 with the interior 4 of the tubular housing.
[0033] Injection devices 20, 22 discharge into the interior 4,
whereby the injection devices 20, 22 discharge quasi inside the
opening 18. A blowing agent under operating pressure can be
introduced into the interior 4 through the injection devices 20,
22. In this way, an operating pressure can be set and maintained in
the interior 4 during the extrusion process, depending on the
blowing agent employed in the extrusion process, generally above 70
bar.
[0034] To produce a layer for absorbing, distributing and
temporarily storing fluid, specifically a polypropylene and/or
polyethylene granulate, can be used as an example of a
thermoplastic polymer. This granulate can be mixed with additives,
such as fibers, for example.
[0035] The mixture obtained in this way is transported into the
interior 4 by means of the conveying device 2. The mixture is
brought up to an operating temperature by the heating devices 12
such that the thermoplastic polymer melts.
[0036] A blowing agent, for example CO.sub.2, is introduced into
the interior 4 through the injection devices 20, 22 so that an
operating pressure obtains there which is suitable for extruding
the partially molten mixture via the extrusion tool 16. Since the
blowing agent is intended to result in foaming of the thermoplastic
polymer, it is preferably introduced into the interior 4 in the
so-called "supercritical stage."
[0037] When the mixture obtained in this way passes through the
extrusion opening of the extrusion tool 16, the blowing agent
expands as result of the accompanying drop in pressure, and the
mixture is foamed, that is to say, pores or cavities which
communicate with each other are formed by the expanding and usually
escaping blowing agent.
[0038] FIGS. 1 and 2 show a top view onto or a sectional view
through, respectively, a two-ply absorbent body 30 of an inventive
sanitary article. The absorbent body 30 comprises a layer for
absorbing, distributing and temporarily storing fluid 32 and a
storage layer 34 disposed on the side of the layer facing away from
the body which comprises a content of at least 50% by weight,
specifically at least 80% by weight, of superabsorbent polymer
materials which can, for example, be embedded in a fibrous
structure (thermoplastic or natural fibers).
[0039] The layer for absorbing, distributing and temporarily
storing fluid is formed from a thermoplastic polymer foamed by
extrusion with the addition of a blowing agent. The polymer
comprises polyethylene and/or polypropylene. In accordance with a
preferred embodiment of the invention between 3% and 30% by weight
of additives in the form of thermoplastic fibers, preferably
polyester fibers, is added. Additionally it can contain
hydrophilizing agents in the form of alkyl sulfonates, fatty acid
derivates or fluorochemicals.
[0040] A porous layer which has a total pore volume of at least 30
ml and which is suitable for the rapid absorption, distribution and
temporary storage of fluid is created by the extrusion of the
thermoplastic polymer with the addition of a blowing agent. The
longitudinal and perpendicular dimensions of layer 32 are less than
those of the storage layer 34 disposed thereunder such that layer
32 is located on all sides within the storage layer 34 in top view.
In this way impinging fluid cannot pass beyond the edges of storage
layer 34 because of the distribution effect within layer 32.
Preferably the surface percentage of layer 32 is about 55%- 90% of
the surface of the storage layer 34. But it must be expressly
pointed out that any other geometric configuration of layer 32
would be conceivable, specifically layer 32 could have the same
length in the longitudinal direction as storage layer 34, which
would be advantageous from the point of view of manufacturing.
[0041] FIG. 4 shows a top view of a further aspect of an absorptive
body 30, in which the layer for absorbing, distributing and
temporarily storing fluid 32 has a varying width b in the
longitudinal direction, which corresponds to the direction of
extrusion. It is hour-glassed shaped in the instance shown.
* * * * *