U.S. patent application number 14/051723 was filed with the patent office on 2014-02-06 for melt-processed films of thermoplastic cellulose and microbial aliphatic polyester.
This patent application is currently assigned to Kimberly-Clark Worldwide, Inc.. The applicant listed for this patent is Kimberly-Clark Worldwide, Inc.. Invention is credited to JadHone Lee, James H. Wang.
Application Number | 20140039435 14/051723 |
Document ID | / |
Family ID | 44152112 |
Filed Date | 2014-02-06 |
United States Patent
Application |
20140039435 |
Kind Code |
A1 |
Wang; James H. ; et
al. |
February 6, 2014 |
Melt-Processed Films of Thermoplastic Cellulose and Microbial
Aliphatic Polyester
Abstract
Films made from a thermoplastic cellulose and
microbially-derived, renewable and biodegradable aliphatic
polyester such as polyhydroxyalkanoates are disclosed. The films,
made from two relatively brittle materials exhibit more ductility
and strength than the materials from which the film is made. The
film may be incorporated into absorbent personal care product
including but not limited to training pants, diaper, bandages, and
bed pads.
Inventors: |
Wang; James H.; (Appleton,
WI) ; Lee; JadHone; (Yongin-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kimberly-Clark Worldwide, Inc. |
Neenah |
WI |
US |
|
|
Assignee: |
Kimberly-Clark Worldwide,
Inc.
Neenah
WI
|
Family ID: |
44152112 |
Appl. No.: |
14/051723 |
Filed: |
October 11, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12645861 |
Dec 23, 2009 |
8586821 |
|
|
14051723 |
|
|
|
|
Current U.S.
Class: |
604/370 ;
524/39 |
Current CPC
Class: |
C08L 67/04 20130101;
C08L 1/14 20130101; A61L 15/225 20130101; Y10T 428/31855 20150401;
C08L 1/10 20130101; C08L 1/10 20130101; C08L 1/02 20130101; C08L
1/26 20130101; C08L 67/04 20130101; C08L 67/04 20130101; C08L 1/26
20130101; C08L 1/14 20130101; A61F 13/51401 20130101; C08L 67/04
20130101; C08L 67/04 20130101; C08L 2666/26 20130101 |
Class at
Publication: |
604/370 ;
524/39 |
International
Class: |
A61L 15/22 20060101
A61L015/22; A61F 13/514 20060101 A61F013/514 |
Claims
1. A melt-processed thermoplastic material film comprising: a blend
of about 5% to about 95% of a thermoplastic cellulose having a
melting point temperature between about 100.degree. C. to about
200.degree. C., and about 5 wt. % to about 95 wt. % of a
polyhydroxyalkanoate with an average molecular weight of at least
20,000 g/mol.
2. The film according to claim 1 wherein the thermoplastic
cellulose comprises cellulose alkanoate with two or more different
alkanoate groups.
3. The film according to claim 1 wherein the thermoplastic
cellulose comprises cellulose acetate butyrate.
4. The film according to claim 1 wherein the thermoplastic
cellulose comprises alkyl cellulose and hydroxyalkyl cellulose.
5. The film according to claim 1 wherein the thermoplastic
cellulose comprises alkyl cellulose and hydroxyalkyl cellulose with
1 to 10 carbon in an alkyl or hydroxyalkyl groups.
6. The film according to claim 1 wherein the thermoplastic
cellulose comprises methyl cellulose, ethyl cellulose, methyl
propyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose,
and/or hydroxybutyl cellulose.
7. The film according to claim 1 wherein the thermoplastic
cellulose comprises cellulose acetate butyrate with a butyrate to
acetate weight ratio of about 1:1 or greater.
8. The film according to claim 9, wherein said cellulose acetate
butyrate has an average molecular weight of at least 20,000
g/mol.
9. The film according to claim 9, wherein said cellulose acetate
butyrate ranges from about 20 wt. % to about 80 wt. % in the
blend.
10. The film according to claim 9, wherein said cellulose acetate
butyrate is 5 wt. % to about 90 wt. %.
11. The film according to claim 1 wherein the thermoplastic
material is in the form of a film having a thickness of about 0.5
to about 4.5 mil in both the machine and cross direction, and
wherein the film comprises about 50 percent cellulose acetate
butyrate and about 50 percent polyhydroxy butyrate.
12. An absorbent article comprising: a backsheet comprising the
film of claim 1; a top sheet attached to the backsheet, and an
absorbent core disposed between the backsheet and topsheet, and
directly attached to either the backsheet or the topsheet.
13. The absorbent article of claim 20 wherein the absorbent article
is configured as a training pant, diaper, an adult incontinent
garment, a feminine pad, a feminine pantiliner, a bandage or a bed
pad.
Description
PRIORITY
[0001] This application is a divisional of application Ser. No.
12/645,861 entitled Melt-Processed Films of Thermoplastic Cellulose
And Microbial Aliphatic Polyester and filed in the U.S. Patent and
Trademark Office on Dec. 23, 2009. The entirety of the prior
application is hereby incorporated by reference in this
application.
BACKGROUND
[0002] The present invention relates to a thermoplastic article. In
particular, the invention pertains to a melt-processed
thermoplastic film that contains a thermoplastic cellulose and a
microbially-derived, renewable and biodegradable aliphatic
polyester. The composition may be incorporated into a variety of
products.
[0003] Because of increasing consumers' concern on environmental
issues and the alleged depletion of fossil fuels, using
environmentally sustainable materials in consumer products has
attracted increased attention in recent decades. From an
environmental sustainability standpoint, cellulose material is an
attractive natural material made from abundant renewable sources
ranging from wood to agricultural waste.
[0004] It is known that some cellulose derivatives can be thermally
processed into various articles such as film and molded articles.
However, the short carbon chain alkanoates derivatives of cellulose
such as cellulose acetate and cellulose propionate have high
melting temperatures making them not suitable for blending with
microbial aliphatic polyester such as poly(3-hydroxybutyrate) due
to its thermal decomposition at processing temperatures.
[0005] In recent years, manufacturers of plastic or thermoplastic
products or materials have shown increasing interest in renewable
biopolymers and cellulose-based materials as important,
environmentally-friendly, natural resources. In fact,
cellulose-based materials are the most abundant natural polymers
that can be renewably produced each year in large quantities.
[0006] Commercially available thermoplastic cellulose derivatives
are cellulose esters and ethers such as cellulose acetate (CA),
cellulose acetate propionate (CAP), and cellulose acetate butyrate
(CAB), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose,
etc. Common properties of these cellulose derivatives are that they
tend to have high stiffness, low ductility, good clarity, and a
narrow thermal processing window. They also have moderate heat and
impact resistance. Unfortunately, the rigid and brittle nature of
cellulose derivatives tends to limit their wider use in a variety
of products and applications.
[0007] Native cellulose is not thermoplastic. Most cellulose esters
have high melting temperatures of over 230 to 240.degree. C. or
higher, while poly(3-hydroxybutyrate) (PHB) has a melting point of
177.degree. C. and a thermal decomposition temperature of about
200.degree. C. Therefore most cellulose esters, even some cellulose
acetate butyrate compositions having high melting points, cannot be
melt blended with PHB due to decomposition of the
polyhydroxyalkanoate (PHA).
[0008] To improve the performance of cellulose ester materials,
blending cellulose derivatives with other polymers has been
explored. The prior art blends of cellulose ester with
biodegradable polymers are prepared by solution blending. Solution
prepared films typically have different morphology and properties
from the films of the same composition produced by melt processing.
This is because melt processing cannot achieve the molecular level
mixing that can be achieved in a solution blending process.
However, the solution blending method is not preferred due to the
use and recovery of solvents as well the corresponding
environmental impact.
[0009] Thus, there is a need for environmentally sustainable films
made from 100% renewable polymers. There is also a need for
renewable polymers such as cellulose for sustainable plastic
applications in personal hygiene and health care products. There is
a further need for a film composition of cellulose and PHA with
suitable melting temperatures and stability during melt processing
without causing PHA to decompose. There is yet another need for
melt-processed films that have suitable mechanical properties such
as enhanced flexibility and ductility.
SUMMARY
[0010] The present invention discloses a new thermoplastic film
that exhibits synergistic properties. Typically, when two rigid
materials are combined, one would expect that the new material
would exhibit the physical attributes between the original two
materials, i.e. following an additivity type linear relationship of
the component polymers. In stark contrast, by the present
invention, it was unexpected to find that the blending of
particular percentages of two usually rigid or non-ductile polymers
can generate a rather ductile film material.
[0011] In one aspect of the present invention is a melt-processed
thermoplastic material film made from a blend of about 5% to about
95% of a thermoplastic cellulose having a melting point temperature
between about 100.degree. C. to about 200.degree. C., and about 5
wt. % to about 95 wt. % of a polyhydroxyalkanoates with an average
molecular weight of at least 20,000 g/mol.
[0012] In another aspect of the present invention is an absorbent
article made with a backsheet comprising the film of a melt
processed thermoplastic material; a top sheet attached to the
backsheet, and an absorbent core disposed between the backsheet and
topsheet, and directly attached to either the backsheet or the
topsheet.
[0013] In yet another aspect of this invention is a packaging film
or article comprising the film of this invention. The packaging
article includes product bags, molded containers, bottles, etc.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 shows a graph that plots the elongation at break of a
polymer blend film as a function of the weight percentage of PHB in
the blend.
[0015] FIG. 2A is a scanning electron microscope (SEM) image of a
cross-section of a sheet of pure CAB film, oriented parallel to a
machine direction (MD) of the film at 2500.times.
magnification.
[0016] FIG. 2B is a SEM image of a cross-section of the sheet of
pure CAB film in FIG. 2A, oriented parallel to a cross-machine
direction (CD) of the film at 2200.times. magnification.
[0017] FIG. 3A is a SEM image of a cross-section of a sheet of
CAB/PHB blend (80%/20%) film, oriented parallel to its MD at
3500.times. magnification.
[0018] FIG. 3B is a SEM image of a cross-section of the sheet of
CAB/PHB blend (80%/20%) film in FIG. 3A, oriented parallel to its
CD at 3000.times. magnification.
[0019] FIG. 4A is a SEM image of a cross-section of a sheet of
CAB/PHB blend (80%/20%) film after oxygen plasma etching, oriented
parallel to its MD at 3500.times. magnification.
[0020] FIG. 4B is a SEM image of a cross-section of the sheet of
CAB/PHB blend (80%/20%) film after oxygen plasma etching in FIG.
4A, oriented parallel to its CD at 2000.times. magnification.
[0021] FIG. 5A is a SEM image of a cross-section of a sheet of
CAB/PHB blend (70%/30%) film, oriented parallel to its MD at
2500.times. magnification.
[0022] FIG. 5B is a SEM image of a cross-section of the sheet of
CAB/PHB blend (70%/30%) film in FIG. 5A, oriented parallel to its
CD at 2300.times. magnification.
[0023] FIG. 6. is a plan view of an absorbent article according to
the present invention.
[0024] FIG. 7 is a perspective view of the absorbent article of
FIG. 6, shown in a partially fastened state.
[0025] FIG. 8A is a cross-sectional view of another embodiment of
an absorbent article of the present invention.
[0026] FIG. 8B is a top perspective view of the absorbent article
of FIG. 8A.
[0027] FIG. 9 is a top perspective view of yet another embodiment
of an absorbent article of the present invention.
DETAILED DESCRIPTION
[0028] Blend compositions used herein are by weight percent of the
composition unless otherwise stated.
[0029] Both cellulose esters and PHB are highly rigid and brittle
polymers. By blending these two polymer compositions together in a
melting process, it was unexpected to find that the film made from
the two rigid polymers has reduced rigidity and increased
ductility. The film also has great clarity, whereas films made from
microbial aliphatic polyester are usually opaque. The blend of the
present invention is stable at melting temperatures to allow for
thermoplastic processing.
[0030] The films of the present invention have at least two
renewable and biodegradable components: 1) plasticized cellulose
derivative (desirably a non-food-based material) and 2) a
biodegradable and renewable polymer such as polyhydroxyalkanoate
(PHA), e.g. poly(3-hydroxybutyrate) (PHB). Thermoplastic blend
films of this invention are flexible and have a relatively high
tensile strength. These properties are desirable for disposable
absorbent product applications. It is known that cellulose
derivatives; such as cellulose acetate, cellulose acetate
propionate, and cellulose acetate butyrate, etc.; can be thermally
processed into various articles such as film, molded articles.
However, the short carbon chain cellulose alkanoates derivatives
such as cellulose acetate and cellulose propionate have high
melting temperatures making them not suitable for blending with
PHA.
[0031] Native cellulose cannot be thermoplastically processed due
to the fact that cellulose has a decomposition temperature lower
than the melting temperature. Modification of the native cellulose
makes it possible to use in thermoplastic applications.
Commercially available thermoplastic cellulose derivatives are
cellulose esters and ethers such as cellulose acetate (CA),
cellulose acetate propionate (CAP), cellulose butyrate, and
cellulose acetate butyrate (CAB), methyl cellulose, ethyl
cellulose, hydroxypropyl cellulose, etc. The thermoplastic
cellulose may include an alkyl cellulose and hydroxyalkyl cellulose
with 1 to 10 carbon in an alkyl or hydroxyalkyl groups. In another
embodiment, the thermoplastic cellulose may include cellulose
alkanoate with 2 to 10 carbon in an alkanoate group. In yet another
embodiment, the thermoplastic cellulose may include cellulose
alkanoate with two or more different alkanoate groups. In a further
embodiment, the thermoplastic cellulose comprises alkyl cellulose
and hydroxyalkyl cellulose with 1 to 10 carbon in an alkyl or
hydroxyalkyl group. In another embodiment, the thermoplastic
cellulose may include methyl cellulose, ethyl cellulose, methyl
propyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose,
and/or hydroxybutyl cellulose. In another embodiment, the
thermoplastic cellulose includes alkyl cellulose and hydroxyalkyl
cellulose.
[0032] The common properties of these native cellulose derivatives
include high stiffness, high tensile strength, low ductility, good
clarity, and narrow thermal processing window. They also have
moderate heat and impact resistance. The rigid and brittle nature
of these cellulose derivatives makes it appropriate for number of
limited applications. To improve the performance, the cellulose
derivatives are blended with other polymers according to the
present invention.
[0033] Not all CAB materials are suitable for this invention. There
are several criteria for selecting CAB for making the film of the
present invention: 1) the composition of CAB or thermoplastic
cellulose has a melting point from 100.degree. C. to about
200.degree. C.; 2) the composition of CAB has a butyrate to acetate
weight ratio of 1 or greater; 3) butyrate content in CAB is
desirably 30% or greater; 4) the molecular weight of CAB is at
least 20,000 g/mol. Higher molecular weight analog such as
alkanoates with five or more carbon are also suitable for this
invention. Typically as the number of carbon in the alkanoate of
cellulose derivative increases, the melting temperature of the
cellulose derivative decreases.
[0034] In one aspect, the desirable thermoplastic cellulose
derivative, cellulose acetate butyrate (CAB), (grade: Tenite
butyrate 485-10, plasticizer: 10% of bis(2-ethylhexyl) adipate,
composition: 37 wt % of butyrate, 13.5 wt % of acetate, DS (degree
of substitution): 2.4.about.2.8), purchased from Eastman
(Minneapolis, Minn.), was used for creating examples listed in this
invention disclosure.
[0035] The average molecular weight of polyhydroxyalkanoate (PHA)
is desirably at least 20,000 g/mol. Short chain or medium chain
PHAs such as poly(3-hydroxybutyrate) (PHB),
poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV),
poly(3-hydroxybutyrate-co-4-hydroxybutyrate (P3HB-4HB),
poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-Hx),
poly(3-hydroxybutyrate-3-hydroxyoctanoate (P3HB-O), etc. can be
utilized in some aspects of this invention.
[0036] One particular example of PHA is PHB: Polyhydroxy butyrate
(PHB) is an isotactic, linear, thermoplastic aliphatic
homopolyester 3-hydroxy butyric acid. PHB is water-insoluble and
highly crystalline (60 to 70%), providing excellent resistance to
solvents. In one aspect, PHB, namely BIOMER P226, may be purchased
from Biomer Ltd. (Germany).
Example 1
[0037] The films of this embodiment of the present invention were
made on a THERMO PRISM USALAB 16 twin screw extruder (Thermo
Electron Corp., Stone, England). The melt blending and film
extrusion were made in the same process, e.g. a direct extrusion
and cast film extrusion process. The extruder had 11 heating zones,
numbered consecutively 1-10 from the feed hopper to the die. 100%
CAB was initially added to a feeder that delivers the material into
the feedthroat of the extruder. The first barrel received the CAB
at a rate of 1 lb/hr. The temperature profile of zones 1 through 10
of the extruder was 175.about.195.degree. C. for each zone (exact
temperatures are listed in Table 1). The die temperature was
180.degree. C. The screw speed was set at 15 rpm and the torque
during extrusion process was 70.about.75%. Film casting was
conducted directly by attaching a 4'' film die on the extruder. The
extruded film from the 4'' die was cooled on the chill-roll of a
film take-up device. The CAB film of the present invention was
clear and had no unmelted particles or other impurities.
Examples 2-6
[0038] The melt blending and film casting of a CAB and PHB blend
was conducted in the manner described above in Example 1. The
temperature profile of zones and operating conditions are listed in
Table 1. All polymers were dry blended and the fed to an extruder.
Film casting was conducted directly by attaching a 4'' film die on
the extruder. The screw speed ranged from 15 to 22 rpm. The torque
during the film extrusion experiments for Examples 2 to 6 ranged
from 28 to 64%.
[0039] Typically, as processing temperatures are reduced, the melt
pressure and torque tend to increase due to increased melt
viscosity. However, the process of melt blending according to the
present invention yielded unexpected results. First, it is shown
that it is possible to substantially reduce the melt processing
temperatures of CAB by blending it with PHB. The die temperature
was reduced from 190.degree. C. to 170.degree. C. This reduces the
energy requirements for processing CAB. For instance, see Examples
2 and 6 as compared to Example 4. For a further energy savings, the
torque was also reduced with the addition of PHB in the
composition.
Example 7
[0040] A film having 100% PHB is made in the manner described above
in Example 1. The first barrel received PHB at a rate of 1.5
lbs/hr. The temperature profile of zone 1 to 10 of the extruder was
155.about.165.degree. C. for each zone, as seen in Table 1. The die
temperature was 165.degree. C. The screw speed was set at 22 rpm
and the torque during extrusion process was 62.about.65%. The
extrusion process and film casting were successfully performed.
TABLE-US-00001 TABLE 1 Blending and Film Casting Condition for
Thermoplastic CAB and PHB Mixture feeding Extruder CAB/PHB rate
speed Extruder Temperature Profile (.degree. C.) P.sub.melt Torque
Sample No. ratio (lb/hr) (rpm) T1 T2 T3 T4 T5 T6 T7 T8 T9 Adaptor
Die psi (%) Example 1 100/0 1 15 175 175 180 180 185 185 195 195
195 195 180 25-30 70~75 Example 2 80/20 1 15 165 170 170 170 175
175 180 180 180 180 180 18~20 34~36 Example 3 70/30 1 15 165 170
170 170 175 175 180 180 180 180 180 14~15 30~32 Example 4 50/50 1.2
20 165 170 170 170 175 175 180 180 180 180 180 12~15 28~32 Example
5 30/70 1.5 20 160 165 165 165 170 170 170 175 175 175 180 9~10
35~38 Example 6 20/80 1.5 20 155 155 155 155 160 160 160 165 165
170 170 9~10 60-64 Example 7 0/100 1.5 22 155 155 155 155 160 160
160 165 165 165 165 8~10 62~65
Tensile Strength:
[0041] The tensile strength of the films of the present invention
was tested according the "Standard Test Method for Tensile
Properties of Plastics," ASTM 938-99, published by the American
Society of Testing and Materials. The tensile properties of the
exemplary films made from the CAB/PHB blends are shown below in
Table 2.
[0042] The tensile tests may be performed on a SINTECH1/D with five
repetitions in both the machine direction (MD) and the cross
direction (CD). Each film sample is cut into a dog-bone shape with
a center width of 3.0 mm. The gauge length is 18.0 mm. During the
test, samples are stretched at a crosshead speed of 12.7 cm (5.0
inches) per minute until breakage occurs. In one example, the
computer program TESTWORKS 4 collected data during the test and
generated a stress (MPa) versus strain (%) curve from which a
variety of properties can be determined: e.g., modulus, peak stress
and elongation.
[0043] The blending of CAB and PHB showed a synergistic effect of
increasing film ductility. For example, the elongation at break of
blending film was greater than that of pure CAB and pure PHB films.
Especially, the elongation at break also was increased
substantially in MD direction from about 3% for pure PHB to about
98% in Example 4. The improvement in the film's elongation or
ductility was unexpected since both the pure CAB and PHB films are
brittle materials.
TABLE-US-00002 TABLE 2 Tensile Properties of Films Film Mechanical
Properties Film Peak Thickness Modulus Stress Elongation Example
Sample (mil.) (Mpa) (Mpa) (%) No. Description Composition MD CD MD
CD MD CD MD CD Example 1 CAB/PHB 100/0 1.9 1.8 1800 1100 82 33 13
38 Example 2 80/20 1.8 2.0 1200 910 63 31 24 82 Example 3 70/30 1.9
1.8 600 540 33 26 56 100 Example 4 50/50 2.2 2.2 120 85 16 14 98
110 Example 5 30/70 1.9 2.1 1100 1000 35 31 35 37 Example 6 20/80
3.9 3.9 1000 1000 30 28 30 19 Example 7 0/100 3.5 3.5 1100 540 21
14 3 2
[0044] It was surprising to find that a low modulus of 120 MPa and
85 MPa respectively for MD and CD at PHB/CAB of 50/50 (Example 4).
At the 50/50 ratio, the modulus reached a minimum, while the
elongation at break reached a maximum (98% and 110% in MD and CD
respectively)
Scanning Electron Microscopy (SEM) Examination of CAB/PHB Blend
Films:
[0045] Machine direction sections were prepared by fracturing the
films in the MD direction after chilling the film samples to a
cryogenic temperature in liquid nitrogen. The cross direction
sections were prepared by cutting the film in the cross-direction
using a cryogenically chilled SUPER-KEEN razor while the sample was
maintained at cryogenic temperature. The sections were mounted
vertically and sputter coated with gold using light burst
applications at low current to significantly reduce any possibility
of sample heating.
[0046] For further evaluation of the film morphologic features,
additional sections were prepared and subjected to oxygen plasma
etching using an Emitech Inc. K1050X plasma etching unit. Three
4-minute treatments at 50 watts were performed. This regimen was
sufficient to provide etching without any evidence of melting.
Generally, different polymers are removed at different rates,
revealing further structural details in a blend. This process was
done for this sample to more clearly confirm the nature of two
polymers on the SEM images.
[0047] All samples were examined using a JEOL 6490LV scanning
electron microscope (SEM) operated at low voltage.
[0048] FIG. 2A is a SEM image of a cross-section of a sheet of pure
CAB film, oriented parallel to a machine direction (MD) of the film
at 2500.times. magnification. This micrograph shows that CAB
exhibits glassy brittle-fracture type morphology.
[0049] FIG. 2B is a SEM image of a cross-section of the sheet of
pure CAB film in FIG. 2A, oriented parallel to a cross-machine
direction (CD) of the film at 2200.times. magnification. This
micrograph shows that CAB also exhibits glassy brittle-fracture
type morphology.
[0050] FIG. 3A is a SEM image of a cross-section of a sheet of a
CAB/PHB blend (80%/20%) film, oriented parallel to its machine
direction at 3500.times. magnification.
[0051] This micrograph shows that CAB forms a continuous glassy
fracture phase and PHB forms an elongated dispersed phase.
[0052] FIG. 3B is a SEM image of a cross-section of the sheet of a
CAB/PHB blend (80%/20%) film in FIG. 3A, oriented parallel to the
sheet cross-direction at 3000.times. magnification. This micrograph
shows that PHB forms a dispersed phase with long, sub-micron
diameter filaments. The fracture surface image has shown that the
PHB dispersed phase had a ductile elongation since the PHB filament
was stretched extensively without breakage, this is quite
unexpected based on the brittle nature of pure PHB. The melt
processing of the thermoplastic films of this invention may have
produced the unique ductile deformation of the blends due to the
unique microstructure.
[0053] FIG. 4A is a SEM image of a cross-section of a sheet of a
CAB/PHB blend (80%/20%) film after oxygen plasma etching, oriented
parallel to the machine-direction at 3500.times. magnification.
This micrograph shows that CAB is the continuous phase, it still
exhibits glassy fracture, plasma etching did not have much effect
on CAB continuous phase.
[0054] FIG. 4B is a SEM image of a cross-section of the sheet of a
CAB/PHB blend (80%/20%) film after oxygen plasma etching in FIG.
4A, oriented parallel to the cross-direction at 2000.times.
magnification. This micrograph shows that voids were formed where
PHB filament were etched out, conforming the microfilament
structure of PHB in the blends.
[0055] FIG. 5A is a SEM image of a cross-section of a sheet of
CAB/PHB blend (70%/30%) film oriented parallel to the
machine-direction at 2500.times. magnification. This micrograph
shows that CAB still exhibits glassy fracture surface and PHB
filament intersections visible.
[0056] FIG. 5B is a SEM image of a cross-section of the sheet of
CAB/PHB blend (70%/30%) film in FIG. 5A, oriented parallel to the
cross-direction at 2300.times. magnification. This micrograph shows
that the CAB component consistently exhibits brittle fracture while
the PHB component occurs as long, mostly sub micron diameter
filaments that are often seen to have partially or completely
pulled out of the section, leaving a void.
Morphology Analysis:
[0057] The pure CAB film of FIGS. 2A and 2B shows that the CAB
component consistently exhibited a brittle fracture-type
morphology. In the blended films, the PHB component occurred as
long, mostly sub-micron diameter filaments that are often seen to
have partially or completely pulled out of the polymer film matrix.
The partial or complete pull-out of the filaments leaves voids, for
example, the voids seen in FIG. 4B.
Example Products
[0058] The film of this invention as be used as a component film in
a number of consumer and industrial products. One example is a
personal care absorbent article. The article include the diapers,
training pants, feminine pantiliners and pads, adult incontinence
pads and pantiliners, adult incontinence pants. The inventive film
can be used as an outer cover film in diapers and training pants,
or as a baffle film in feminine and adult pads or pantiliners.
[0059] To gain a better understanding of the present invention,
attention is directed to FIG. 6 and FIG. 7 for exemplary purposes
showing a training pant of the present invention. It is understood
that the present invention is suitable for use with various other
absorbent articles, including but not limited to other personal
care absorbent articles, health/medical absorbent articles,
household/industrial absorbent articles, sports/construction
absorbent articles, and the like, without departing from the scope
of the present invention.
[0060] Various materials and methods for constructing training
pants are disclosed in U.S. Pat. No. 6,761,711 to Fletcher et al.;
U.S. Pat. Nos. 4,940,464 to Van Gompel et al.; 5,766,389 to Brandon
et al., and 6,645,190 to Olson et al., each of which is
incorporated herein by reference in a manner that is consistent
herewith.
[0061] FIG. 7 illustrates a training pant in a partially fastened
condition, and FIG. 6 illustrates a training pant in an opened and
unfolded state. The training pant defines a longitudinal direction
48 that extends from the front of the training pant when worn to
the back of the training pant. Perpendicular to the longitudinal
direction 1 is a lateral direction 49.
[0062] The pair of training pants defines a front region 22, a back
region 24, and a crotch region 26 extending longitudinally between
and interconnecting the front and back regions. The pant also
defines an inner surface (i.e., body-facing surface) adapted in use
(e.g., positioned relative to the other components of the pant) to
be disposed toward the wearer, and an outer surface (i.e.,
garment-facing surface) opposite the inner surface. The training
pant has a pair of laterally opposite side edges and a pair of
longitudinally opposite waist edges.
[0063] The illustrated pant 20 may include a chassis 32, a pair of
laterally opposite front side panels 34 extending laterally outward
at the front region 22 and a pair of laterally opposite back side
panels 134 extending laterally outward at the back region 24.
[0064] The chassis 32 includes a backsheet 40 and a topsheet 42
that may be joined to the backsheet 40 in a superimposed relation
therewith by adhesives, ultrasonic bonds, thermal bonds or other
conventional techniques. The inventive film can be used as
backsheet 40 in the illustration. The chassis 32 may further
include an absorbent core 44 such as shown in FIG. 2 disposed
between the backsheet 40 and the topsheet 42 for absorbing fluid
body exudates exuded by the wearer, and may further include a pair
of containment flaps 46 secured to the topsheet 42 or the absorbent
core 44 for inhibiting the lateral flow of body exudates.
[0065] The backsheet 40, the topsheet 42 and the absorbent core 44
may be made from many different materials known to those skilled in
the art. All three layers, for instance, may be extensible and/or
elastically extensible. Further, the stretch properties of each
layer may vary in order to control the overall stretch properties
of the product.
[0066] The backsheet 40, for instance, may be breathable and/or may
be fluid impermeable. The backsheet 40 may be constructed of a
single layer, multiple layers, laminates, spunbond fabrics, films,
meltblown fabrics, elastic netting, microporous webs or
bonded-carded-webs. The backsheet 40, for instance, can be a single
layer of a fluid impermeable material, or alternatively can be a
multi-layered laminate structure in which at least one of the
layers is fluid impermeable. The backsheet 40 can be biaxially
extensible and optionally biaxially elastic. Elastic non-woven
laminate webs that can be used as the backsheet 40 include a
non-woven material joined to one or more gatherable non-woven webs
or films. Stretch bonded laminates (SBL) and neck bonded laminates
(NBL) are examples of elastomeric composites.
[0067] Examples of suitable nonwoven materials are
spunbond-meltblown fabrics, spunbond-meltblown-spunbond fabrics,
spunbond fabrics, or laminates of such fabrics with films, or other
nonwoven webs. Elastomeric materials may include cast or blown
films, meltblown fabrics or spunbond fabrics composed of
polyethylene, polypropylene, or polyolefin elastomers, as well as
combinations thereof. The elastomeric materials may include PEBAX
elastomer (available from AtoFine Chemicals, Inc., a business
having offices located in Philadelphia, Pa. U.S.A.), HYTREL
elastomeric polyester (available from Invista, a business having
offices located in Wichita, Kans. U.S.A.), KRATON elastomer
(available from Kraton Polymers, a business having offices located
in Houston, Tex., U.S.A.), or strands of LYCRA elastomer (available
from Invista), or the like, as well as combinations thereof. The
backsheet 40 may include materials that have elastomeric properties
through a mechanical process, printing process, heating process or
chemical treatment. For example, such materials may be apertured,
creped, neck-stretched, heat activated, embossed, and
micro-strained, and may be in the form of films, webs, and
laminates.
[0068] One example of a suitable material for a biaxially
stretchable backsheet 40 is a breathable elastic film/nonwoven
laminate, such as described in U.S. Pat. No. 5,883,028, to Morman
et al., incorporated herein by reference in a manner that is
consistent herewith. Examples of materials having two-way
stretchability and retractability are disclosed in U.S. Pat. Nos.
5,116,662 to Morman and 5,114,781 to Morman, each of which is
incorporated herein by reference in a manner that is consistent
herewith. These two patents describe composite elastic materials
capable of stretching in at least two directions. The materials
have at least one elastic sheet and at least one necked material,
or reversibly necked material, joined to the elastic sheet at least
at three locations arranged in a nonlinear configuration, so that
the necked, or reversibly necked, web is gathered between at least
two of those locations.
[0069] The topsheet 42 is suitably compliant, soft-feeling and
non-irritating to the wearers skin. The topsheet 42 is also
sufficiently liquid permeable to permit liquid body exudates to
readily penetrate through its thickness to the absorbent core 44. A
suitable topsheet 42 may be manufactured from a wide selection of
web materials, such as porous foams, reticulated foams, apertured
plastic films, woven and non-woven webs, or a combination of any
such materials. For example, the topsheet 42 may include a
meltblown web, a spunbonded web, or a bonded-carded-web composed of
natural fibers, synthetic fibers or combinations thereof. The
topsheet 42 may be composed of a substantially hydrophobic
material, and the hydrophobic material may optionally be treated
with a surfactant or otherwise processed to impart a desired level
of wettability and hydrophilicity.
[0070] The topsheet 42 may also be extensible and/or
elastomerically extensible. Suitable elastomeric materials for
construction of the topsheet 42 can include elastic strands, LYCRA
elastics, cast or blown elastic films, nonwoven elastic webs,
meltblown or spunbond elastomeric fibrous webs, as well as
combinations thereof. Examples of suitable elastomeric materials
include KRATON elastomers, HYTREL elastomers, ESTANE elastomeric
polyurethanes (available from Noveon, a business having offices
located in Cleveland, Ohio U.S.A.), or PEBAX elastomers. The
topsheet 42 can also be made from extensible materials such as
those described in U.S. Pat. No. 6,552,245 to Roessler et al. which
is incorporated herein by reference in a manner that is consistent
herewith. The topsheet 42 can also be made from biaxially
stretchable materials as described in U.S. Pat. No. 6,969,378 to
Vukos et al. which is incorporated herein by reference in a manner
that is consistent herewith.
[0071] The article 20 can optionally further include a surge
management layer which may be located adjacent the absorbent core
44 and attached to various components in the article 20 such as the
absorbent core 44 or the topsheet 42 by methods known in the art,
such as by using an adhesive. In general, a surge management layer
helps to quickly acquire and diffuse surges or gushes of liquid
that may be rapidly introduced into the absorbent structure of the
article. The surge management layer can temporarily store the
liquid prior to releasing it into the storage or retention portions
of the absorbent core 44. Examples of suitable surge management
layers are described in U.S. Pat. Nos. 5,486,166 to Bishop et al.;
5,490,846 to Ellis et al.; and 5,820,973 to Dodge et al., each of
which is incorporated herein by reference in a manner that is
consistent herewith.
[0072] The article 20 can further comprise an absorbent core 44.
The absorbent core 44 may have any of a number of shapes. For
example, it may have a 2-dimensional or 3-dimensional
configuration, and may be rectangular shaped, triangular shaped,
oval shaped, race-track shaped, I-shaped, generally hourglass
shaped, T-shaped and the like. It is often suitable for the
absorbent core 44 to be narrower in the crotch portion 26 than in
the rear 24 or front 22 portion(s). The absorbent core 44 can be
attached in an absorbent article, such as to the backsheet 40
and/or the topsheet 42 for example, by bonding means known in the
art, such as ultrasonic, pressure, adhesive, aperturing, heat,
sewing thread or strand, autogenous or self-adhering,
hook-and-loop, or any combination thereof.
[0073] The absorbent core 44 can be formed using methods known in
the art. While not being limited to the specific method of
manufacture, the absorbent core can utilize forming drum systems,
for example, see U.S. Pat. No. 4,666,647 to Enloe et al., U.S. Pat.
No. 4,761,258 to Enloe, U.S. Pat. No. 6,630,088 to Venturino et
al., and U.S. Pat. No. 6,330,735 to Hahn et al., each of which is
incorporated herein by reference in a manner that is consistent
herewith. Examples of techniques which can introduce a selected
quantity of optional superabsorbent particles into a forming
chamber are described in U.S. Pat. No. 4,927,582 to Bryson and U.S.
Pat. No. 6,416,697 to Venturino et al., each of which is
incorporated herein by reference in a manner that is consistent
herewith.
[0074] In some desirable aspects, the absorbent core includes
cellulose fiber and/or synthetic fiber, such as meltblown fiber,
for example. Thus, in some aspects, a meltblown process can be
utilized, such as to form the absorbent core in a coform line. In
some aspects, the absorbent core 44 can have a significant amount
of stretchability. For example, the absorbent core 44 can comprise
a matrix of fibers which includes an operative amount of
elastomeric polymer fibers. Other methods known in the art can
include attaching superabsorbent polymer particles to a stretchable
film, utilizing a nonwoven substrate having cuts or slits in its
structure, and the like.
[0075] The absorbent core 44 can additionally or alternatively
include absorbent and/or superabsorbent material. Accordingly, the
absorbent core 44 can comprise a quantity of superabsorbent
material and optionally fluff contained within a matrix of fibers.
In some aspects, the total amount of superabsorbent material in the
absorbent core 44 can be at least about 10% by weight of the core,
such as at least about 30%, or at least about 60% by weight or at
least about 90%, or between about 10% and about 98% by weight of
the core, or between about 30% to about 90% by weight of the core
to provide improved benefits. Optionally, the amount of
superabsorbent material can be at least about 95% by weight of the
core, such as up to 100% by weight of the core. In other aspects,
the amount of absorbent fiber of the present invention in the
absorbent core 44 can be at least about 5% by weight of the core,
such as at least about 30%, or at least about 50% by weight of the
core, or between about 5% and 90%, such as between about 10% and
70% or between 10% and 50% by weight of the core. In still other
aspects, the absorbent core 44 can optionally comprise about 35% or
less by weight unmodified fluff, such as about 20% or less, or 10%
or less by weight unmodified fluff.
[0076] It should be understood that the present invention is not
restricted to use with superabsorbent material and optionally
fluff. In some aspects, the absorbent core 44 may additionally
include materials such as surfactants, ion exchange resin
particles, moisturizers, emollients, perfumes, fluid modifiers,
odor control additives, and the like, and combinations thereof. In
addition, the absorbent core 44 can include a foam.
[0077] In addition to the absorbent article described above, the
present invention may be exemplified as an absorbent bandage.
Attention is directed to FIGS. 8A and 8B, which show a possible
configuration for a bandage of the present invention. FIG. 8A shows
a cross-section view of the absorbent bandage with optional layers
described below. FIG. 8B shows a perspective view of the bandage of
the present invention with some of the optional or removable layers
not being shown. The absorbent bandage 150 has a strip 151 of
material having a body-facing side 159 and a second side 158 which
is opposite the body-facing side. The strip is essentially a
backsheet and is desirably prepared from the same materials
described above for the backsheet. In addition, the strip may be an
apertured material, such as an apertured film, or material which is
otherwise gas permeable, such as a gas permeable film. The strip
151 supports an absorbent core 152 comprising the superabsorbent
polymer composition of the present invention which is attached to
the body-facing side 159 of the strip. In addition, an absorbent
protective layer 153 may be applied to the absorbent core 152 and
can be coextensive with the strip 151. The inventive film can be
used as strip 151.
[0078] The absorbent bandage 150 of the present invention may also
have a pressure sensitive adhesive 154 applied to the body-facing
side 159 of the strip 151. Any pressure sensitive adhesive may be
used, provided that the pressure sensitive adhesive does not
irritate the skin of the user. Suitably, the pressure sensitive
adhesive is a conventional pressure sensitive adhesive which is
currently used on similar conventional bandages. This pressure
sensitive adhesive is desirably not placed on the absorbent core
152 or on the absorbent protective layer 153 in the area of the
absorbent core 152. If the absorbent protective layer is
coextensive with the strip 151, then the adhesive may be applied to
areas of the absorbent protective layer 153 where the absorbent
core 152 is not located. By having the pressure sensitive adhesive
on the strip 151, the bandage is allowed to be secured to the skin
of a user in need of the bandage. To protect the pressure sensitive
adhesive and the absorbent, a release strip 155 can be placed on
the body-facing side 159 of the bandage. The release liner may be
removably secured to the article attachment adhesive and serves to
prevent premature contamination of the adhesive before the
absorbent article is secured to, for example, the skin. The release
liner may be placed on the body-facing side of the bandage in a
single piece (not shown) or in multiple pieces, as is shown in FIG.
10A.
[0079] In another aspect of the present invention, the absorbent
core of the bandage may be placed between a folded strip. If this
method is used to form the bandage, the strip is suitably fluid
permeable.
[0080] Absorbent furniture and/or bed pads or liners are also
included within the present invention. As is shown in FIG. 9, a
furniture or bed pad or liner 160 (hereinafter referred to as a
"pad") is shown in perspective. The pad 160 has a fluid impermeable
backsheet 161 having a furniture-facing side or surface 168 and an
upward facing side or surface 169 which is opposite the
furniture-facing side or surface 168. The fluid impermeable
backsheet 161 supports the absorbent core 162 which comprises the
superabsorbent polymer composition of the present invention, and
which is attached to the upward facing side 169 of the fluid
impermeable backsheet. In addition, an optional absorbent
protective layer 163 may be applied to the absorbent core. The
optional substrate layer of the absorbent core can be the fluid
impermeable layer 161 or the absorbent protective layer 163 of the
pad. The inventive film can be used as the backsheet 161 in FIG.
9.
[0081] To hold the pad in place, the furniture-facing side 168 of
the pad may contain a pressure sensitive adhesive, a high friction
coating or other suitable material which will aid in keeping the
pad in place during use. The pad of the present invention can be
used in a wide variety of applications including placement on
chairs, sofas, beds, car seats and the like to absorb any fluid
which may come into contact with the pad.
[0082] It will be appreciated that details of the foregoing
embodiments, given for purposes of illustration, are not to be
construed as limiting the scope of this invention. Although only a
few exemplary embodiments of this invention have been described in
detail above, those skilled in the art will readily appreciate that
many modifications are possible in the exemplary embodiments
without materially departing from the novel teachings and
advantages of this invention. For example, the film may be used as
a packaging film or articles such as product bags, molded
containers, bottles, etc. Accordingly, all modifications are
intended to be included within the scope of this invention, which
is defined in the following claims and all equivalents thereto.
Further, it is recognized that many embodiments may be conceived
that do not achieve all of the advantages of some embodiments,
particularly of the preferred embodiments, yet the absence of a
particular advantage shall not be construed to necessarily mean
that such an embodiment is outside the scope of the present
invention.
* * * * *