U.S. patent application number 17/178085 was filed with the patent office on 2022-09-01 for repulpable and recyclable composite packaging articles and related methods.
This patent application is currently assigned to Smart Planet Technologies, Inc.. The applicant listed for this patent is Smart Planet Technologies, Inc.. Invention is credited to Christopher R. Tilton.
Application Number | 20220275165 17/178085 |
Document ID | / |
Family ID | 1000006344956 |
Filed Date | 2022-09-01 |
United States Patent
Application |
20220275165 |
Kind Code |
A1 |
Tilton; Christopher R. |
September 1, 2022 |
Repulpable And Recyclable Composite Packaging Articles And Related
Methods
Abstract
Unexpectedly unique and environmentally friendly composite
material structures, storage articles fabricated therefrom, and
related methods. The composite structure includes at least one or
more fiber-containing layers, such as fiberboard or other layers
having fibers from natural and/or synthetic sources, and one or
more mineral-containing layers. The mineral-containing layer(s)
comprises a thermoplastic bonding agent fixing the mineral
particles in place. The fiber-containing layer(s) and
mineral-containing layer(s) can be shaped, sized, and manufactured
such that the composite structure formed therefrom is capable of
being machined to form the storage article. The composite structure
can be repulped and recycled without the use of dispersions,
emulsions, or aqueous solutions. Further, the composite reduces
layer mass requirements for heat seal, barrier, and fiber adhesion
compared to polymer layers. The composite structure further has
tensile strength and other structural characteristics that allow it
to be readily machined into desired storage article forms.
Inventors: |
Tilton; Christopher R.;
(Laguna Hills, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Smart Planet Technologies, Inc. |
Newport Beach |
CA |
US |
|
|
Assignee: |
Smart Planet Technologies,
Inc.
Newport Beach
CA
|
Family ID: |
1000006344956 |
Appl. No.: |
17/178085 |
Filed: |
February 17, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16503280 |
Jul 3, 2019 |
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17178085 |
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15487928 |
Apr 14, 2017 |
10421848 |
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16503280 |
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14211180 |
Mar 14, 2014 |
9637866 |
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15487928 |
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61879888 |
Sep 19, 2013 |
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61782291 |
Mar 14, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B27N 3/28 20130101; B32B
2439/00 20130101; C08J 2323/06 20130101; B32B 2307/72 20130101;
C08J 11/06 20130101; B27N 3/04 20130101; B05D 2252/00 20130101;
D21H 5/12 20130101; D21F 11/12 20130101; B05D 1/265 20130101; B32B
2260/046 20130101; Y10T 428/259 20150115; B32B 27/20 20130101; C08K
3/26 20130101; Y10T 428/264 20150115; Y10T 428/258 20150115; B32B
2264/10 20130101; B32B 27/12 20130101; C08J 5/045 20130101; B32B
2260/025 20130101; C08K 2003/265 20130101; B32B 19/02 20130101;
Y10T 428/24967 20150115; D21J 1/08 20130101; B32B 2307/7246
20130101; B32B 2307/702 20130101 |
International
Class: |
C08J 11/06 20060101
C08J011/06; D21F 11/12 20060101 D21F011/12; B32B 27/12 20060101
B32B027/12; B32B 19/02 20060101 B32B019/02; B32B 27/20 20060101
B32B027/20; D21H 15/00 20060101 D21H015/00; D21J 1/08 20060101
D21J001/08; C08J 5/04 20060101 C08J005/04; B27N 3/04 20060101
B27N003/04; B27N 3/28 20060101 B27N003/28; C08K 3/26 20060101
C08K003/26 |
Claims
1-13. (canceled)
14. A method of making a packaging layer from a paper, wherein the
paper comprises a mineral containing barrier layer coupled to a
fiber layer, and wherein the mineral containing layer comprises a
thermoplastic bonding agent, comprising: pulping the paper to
produce released fibers and mineral containing layer fragments;
compounding the pulp to intersperse particles in the thermoplastic
resin to have a density ranging from about 1.01 g/cm.sup.3 to about
4.25 g/cm.sup.3; extrusion coating the thermoplastic resin to form
a packaging layer, collecting the packaging for recycling and
depositing the collected packages into a paper recycling machine
pulper; wherein the packaging layer has a higher density than
water; upon recycling, the packaging layer improving the quality of
the pulp; and the packaging layer having a higher structural
brittleness and crystallinity such that it improves the recycling
process by forming unique particles and fragments in the pulp.
15. The method of claim 1, wherein the thermoplastic content in the
pulp separates and breaks into fragments and particles containing
thermoplastic and other particles having a size between 0.05
mm.sup.2 and up to 2 mm.sup.2.
16. The method of claim 1, wherein the recycling process is
continued until the screen yield is at least 77%, wherein the
screen is a slotted and round screen with 0.01'' slot openings.
17. The method of claim 1, wherein the released fibers pass through
screening plates having hole screen openings with a diameter of
about 0.8 mm to about 1.5 mm.
18. The method of claim 4, wherein the screening plates comprise a
hole screen, a slotted screen, and a contoured screen.
19. The method of claim 1 wherein the fiber component comprises
softwood fibers, hardwood fibers, or a mixture thereof.
20. The method of claim 1, further comprising using high density,
forward, and through flow cleaners to separate the mineral
containing impurities from the pulp.
21. The method of claim 7, wherein the cleaners have a diameter of
from about 70 mm to about 400 mm.
22. The method of claim 1, further comprising using centrifugal
cleaners to separate the mineral containing impurities from the
pulp.
23. The method of claim 1, wherein the minerals in the mineral
containing layer have physical properties as shown in Table 2.
24. The method of claim 1, wherein the minerals in the mineral
containing layer have a particle size between from 0.1 micron to
10.0 micron, or a particle size of less than 100 nanometers.
25. The method of claim 1, wherein the minerals in the mineral
containing layer are nanoparticles having a size range from 0.06
microns to 0.15 microns.
26. The method of claim 1, wherein the minerals in the mineral
containing layer have shapes comprising spheres, rods, cubes,
blocks, flakes, platelets, and irregular shapes.
27. A pulp of a paper, wherein the paper comprises a mineral
containing barrier layer and a fiber containing layer, having the
characteristics, comprising: the paper having a structural
brittleness to release fibers from the barrier layer and pass
through a screen having one or more hole screen openings with a
diameter of about 0.8 mm to about 1.5 mm; and the pulp having a
crystallinity from 60% to 95%
Description
[0001] This application is a continuation application of U.S.
patent application Ser. No. 16/503,280 filed Jul. 3, 2019, which is
a divisional application of U.S. patent application Ser. No.
15/487,928 filed Apr. 14, 2017, which issued as U.S. Pat. No.
10,421,848 on Sep. 24, 2019, which is a continuation of U.S. patent
application Ser. No. 14/211,180, filed Mar. 14, 2014, which issued
as U.S. Pat. No. 9,637,866 on May 2, 2017, and claims priority to
provisional application Ser. No. 61/879,888, filed on Sep. 19,
2013, and to provisional application Ser. No. 61/782,291, filed on
Mar. 14, 2013. These and all other referenced extrinsic materials
are incorporated herein by reference in their entirety. Where a
definition or use of a term in a reference that is incorporated by
reference is inconsistent or contrary to the definition of that
term provided herein, the definition of that term provided herein
is deemed to be controlling.
FIELD OF THE INVENTION
[0002] The present embodiments relate generally to repulpable and
recyclable composite packaging materials and/or finished packaging
structures.
BACKGROUND
[0003] Packages and packaging materials for retail and shipping
purposes are typically designed to be sufficiently durable to allow
reliable use of the materials and protection of packaged goods. For
environmental and economic reasons, pulping and recycling
characteristics are critical considerations in the development of
such packages and materials. Other important considerations include
barrier performance, heat seal during fabrication, surface energy,
and efficiency in manufacturing.
SUMMARY OF THE INVENTION
[0004] Compositions and methods that provide for a composite
material that is readily recyclable are provided. The composite
material is configured to generate polymer-containing particles
that are readily separable from fibrous content when subjected to
recycling operations.
[0005] One embodiment of the inventive concept is a method of
recycling a composite material (e.g. such as a composite material
having a caliper of about 0.254 mm to about 0.762 mm), where the
method includes obtaining a composite material having a fiber layer
and a barrier layer that is coupled to the fiber layer. This
barrier layer includes a mineral containing layer having a mineral
content of 15% to 70%. The composite material is pulped to produce
released fibers and mineral containing layer fragments. These
mineral containing layer fragments have an area of about 0.01
mm.sup.2 to about 5 mm.sup.2 and a density ranging from about 1.01
g/cm.sup.3 to about 4.25 g/cm.sup.3. Unwanted materials, which
include at least a portion of the mineral containing layer
fragments, are separated from the released fibers by a screening
process having a rejection rate of less than 25% by weight of the
composite material and a screen cleanliness efficiency is greater
than 60%. In some embodiments the screening process includes
applying a suspension that includes the released fibers to one or
more screening plates (e.g. a hole screen, a slotted screen, and a
contoured screen). Suitable hole screens can have one or more hole
screen openings having a diameter of about 0.8 mm to about 1.5 mm.
Suitable slotted screens can have one or more slotted screen
openings having a width of about 0.1 mm to about 0.4 mm. Suitable
contoured screens can have one or more contoured screen openings
having a width of about 0.1 mm to about 0.4 mm. The pressure drop
across such screening plates can be less than about 12 kPa of
Feed-Accept pressure.
[0006] In some embodiments the method includes a post-screening
process step, which can include centrifugal cleaning of screen
accepts (for example, using a tapered cylinder). Such screen
accepts can include at least a portion of the unwanted materials
and at least a portion of the released fibers. This produces
cleaned fibers (e.g. the released fibers separated from the
unwanted materials) that are carried inward to an accepted stock
inlet. The unwanted materials include at least a portion of the
mineral containing layer fragments, and more than 70% by mass of
the mineral containing layer fragments of the unwanted materials
are removed from the screen accepts in this process. Such mineral
containing layer fragments are at least partially spherical and
have a diameter of about 0.05 .mu.m to about 150 .mu.m. Overall
recovery of the fiber layer of the composite is greater than about
70%.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The present embodiments now will be discussed in detail with
an emphasis on highlighting the advantageous features. These
embodiments depict the novel and non-obvious repulpable and
recyclable composite packaging articles and related methods shown
in the accompanying drawings, which are for illustrative purposes
only. These drawings include the following figures, in which like
numerals indicate like parts:
[0008] FIG. I is a schematic side cross-sectional view of a
multilayer repulpable packaging composite material according to the
present embodiments;
[0009] FIG. IA is a detail view of the portion of FIG. I indicated
by the circle IA-IA;
[0010] FIG. 2 is a schematic side cross-sectional view of another
multilayer repulpable packaging composite material according to the
present embodiments;
[0011] FIG. 3 is a schematic side cross-sectional view of a
repulpable mineral-containing material according to the present
embodiments;
[0012] FIG. 4 is a schematic detail view of a pellet of a
mineral-containing resin with mineral particles interspersed within
a bonding agent according to the present embodiments;
[0013] FIG. 5 is a schematic side cross-sectional view of another
multilayer repulpable packaging composite material according to the
present embodiments; and
[0014] FIG. 6 is a schematic side cross-sectional view of another
multilayer repulpable packaging composite material according to the
present embodiments;
[0015] FIG. 7 is a graph showing the stickies content of Sample 6 #
from Table 12;
[0016] FIG. 8 is a graph showing a total ion spectrum of DCM
extract from a washout fraction of sample CL WR-2;
[0017] FIG. 9 is an envelope formed from a composite material
according to the present embodiments; and
[0018] FIG. IO is a display tray formed from a composite material
according to the present embodiments.
[0019] FIG. 11 is an envelope formed from a composite material
according to the present embodiments; and
[0020] FIG. 12 is a display tray found formed from a composite
material according to the present embodiments.
DETAILED DESCRIPTION
[0021] The present embodiments relate to methods and compositions
providing repulpable and recyclable consumer packaging for
containing, for example and without limitation, food products, dry
goods, detergents, etc. More particularly, the present embodiments
include using mineral-containing layer(s), minerals bonded by
thermoplastic polymers and subsequently adhered to fiber-containing
layer(s) using extrusion coating, extrusion lamination, or
lamination adhering the mineral-containing layer continuously and
substantially to the surface or surfaces of natural
fiber-containing layers such that the finished package can be
effectively repulped and recycled using both pre-consumer and
postconsumer collection methods. The present embodiments provide
reusable pulp, thus offering reusability and reprocess ability into
valuable recycled paper-containing packaging products. The present
packaging composites can be used to form one or more layers of all
types of single-layer and multilayer packaging structures, e.g.
folding cartons and the like, including single-wall or multi-wall
corrugated structures using the composite packaging material as one
or more inner or outer liner(s) and/or corrugated medium(s).
[0022] It is current practice, for example, to add a film of
polyethylene (PE), polypropylene (PP), polyester, wax, or
polyvinylidene chloride (PVDC) on paper substrates to provide a
moisture barrier. Also, various types of emulsion and aqueous
coatings are applied to paper substrates for the same reason.
However, it is believed that there are no repulpable and recyclable
solutions that offer the efficiencies of high speed thermoplastic
extrusion coating of mineral-containing pellets forming a layer.
The present embodiments provide finished composite materials having
high barrier performance, heat sealability, high performance
adhesion to fiber, strength, repulpability, and low cost of
manufacture. Further, other resins may be used to give packaging
materials barrier performance, such as polyacrylates, polyvinyl
acetates, and the like. However, these materials are more expensive
than wax, polyethylene and PVDC. Predominantly, barrier
alternatives are considered by recycling (repulping) mills to be
non-repulpable, mainly because they introduce quality problems in
the fiber recovery process, either by upsetting the process, e.g.
by plugging filter screens, or by contaminating the finished
product. Approximately 20% of known paperboards are laminated with
the materials listed above, or similar materials, resulting in
products that are incompatible within the recycling industry.
[0023] A major drawback to polyolefin and other polymer coatings,
such as wax, acrylic, polyethylene terephthalate (PET) dispersions,
and PVDC barrier layers, is that they are either difficult to
reprocess or recycle and usually discarded, or they can only be
processed at a recycling mill with specialized equipment, or, if
processible, provide inferior barrier and heat seal performance for
packaging articles such as cups or heat sealed folding cartons. For
environmental and cost reasons, the disposal of moisture barrier
packaging materials has become an important issue for paper mills
and their customers. Repulping these materials poses special
problems for the industry. The moisture barrier layer manifests
problems in recovering the useful fiber from the package.
Presently, nearly all of these packages are ultimately discarded
into landfills or incinerated, which raises issues with respect to
the environment and public health, particularly for PVDC.
Reprocessing packaging to recover wood fibers is an important
source of wood fibers, and helps avoid waste of high quality and
costly fibers.
[0024] When forming packaging that contains food products and dry
goods, heat scalability is often important for closures. Also, the
packaging structure preferably provides a barrier for moisture,
oxygen, oils, and fatty acids. Other desirable characteristics
include mechanical performance, aesthetics, cosmetics, resistance
to chemicals, recyclability, heat sealability, surface energy, ink
adhesion, ink wet-ability, film adhesion to fibers, improved
surface for glue and adhesive application, and barrier performance
(against oxygen, water, moisture, etc.). Therefore, extrusion
coating fiber surfaces using polymers, (polyolefins being the most
common) and bio-polymers is common practice.
[0025] Two methods are commonly used for reprocessing wood fibers.
The first method breaks up the source of wood fibers, such as
packaging materials, by repulping, while other materials are
filtered out. The second method breaks up the packaging materials
such that any non-fibrous material breaks up into tiny pieces
(generally smaller than 1.6 mm), which then pass through the filter
screen(s) with the wood fibers to constitute a pulp. This second
method is frequently carried out with chemical additives and/or
additional equipment, making it expensive and therefore
undesirable.
[0026] However, no known resins, with our without wax, used in
high-performance barrier layers, can be reprocessed without
additional manufacturing steps. Recycling these materials is
therefore difficult if not impossible. Additionally, the presence
of wax in resins frequently results in a lower quantity of usable
pulp, and therefore increases the amount of waste. In the repulping
process, waste materials may break up into very tiny particles,
often smaller than 0.7 mm. These particles pass through the filter
screen(s) and contaminate pulp that is sent to the paper machine.
Problems repulping wax include clogging the felts, gumming up the
can dryer causing web breaks, sticky related unacceptable paper
surface cosmetics, and yield reduction.
[0027] The repulping of PE and PP barrier layers (as with most
polymers) is very difficult. During reprocessing, while polyolefin
is in the pulper, it separates from the fiber and the polyolefin
breaks into large pieces with estimated widths from about 0.3 cm to
3.0 cm, or larger pieces and particles having densities in a range
from about 0.875 g/cm.sup.3 to about 0.995 g/cm3 and higher. These
pieces cause screen plugging, requiring expensive downtime to
clean, and generate solid waste. However, mineralized layers when
repulped break down into a preponderance of from about 35% to about
99% of much smaller and more dense fragments in sizes of from about
0.0005 mm.sup.2 to about 2 mm.sup.2 or larger, having densities
from about 1.10 g/cm.sup.3 to about 4.75 g/cm.sup.3. These unique
particles provide improved repulping and recycling processing
benefits. Therefore, the mineral-containing layers can be applied
successfullyto fiber-containing layers with improved re-pulpability
vs. polymer layers with mineral-containing layers applied in coat
weights in the range of from about 4 lbs/msf (pounds per thousand
square feet) to about 25 lbs/msf. The processing of the mineralized
layer composite material can be accomplished using industry
standard repulping and recycling equipment, much of which is
further described in this specification.
[0028] Also, for normal processing it is important for the recycler
to use a standard pulper equipped with a steam line, using typical
screens of various sizes and an operating centrifuge. PVDC coating
also has generally the same processing issues as PE. Further, other
options such as emulsion and aqueous coating with vinyl content
cannot provide comparable barrier performance or high performance
heat scalability at low cost. Also, mixing at the point of
manufacture is often required and single or multiple layers of
vinyl plus separate layers for minerals, for example, may be
required. Also, unlike polyolefins, barrier failure is quite common
using these types of layers at points of package stress or fracture
during converting or subsequent use. Finally, PVDC and related
coatings provide major environmental toxic hazards and are
therefore a poor option as a barrier layer.
[0029] During repulping, non-fibrous barrier layers must be
structurally brittle enough to break into small enough pieces to
ensure the fibers efficiently release from the barrier layer and
pass through the screen(s). Also, the pulped barrier layer
fragments must not be too small to pass through the screen(s) and
create process difficulties in the paper making machine. Finally,
the pulped barrier layer pieces cannot be so large as to clog the
screen(s) and foul the filtering process.
[0030] By introducing mineral content into a thermoplastic barrier
layer using proper particle specifications and proper amounts of
minerals added, the mineral-containing polyolefin layer obtains
structural attributes providing for efficient, clean, and proper
processing during the pulping process. Also, a 20%-70% mineralized
layer easily releases fiber content through the screen(s),
resulting in high fiber yields. Further, by using an extrusion
coated thermoplastic, high speed, efficient production applying the
barrier layer to the fiber can be enjoyed using common processes
such as extrusion coating. Without the need for water based or
other dispersions, press line applications, emulsions, or use of
single or multiple layers containing vinyl, adjunct or additional
layers of similar materials or minerals, the thermoplastic content
acts as a bonding agent for the particles, bonding the mineral
particles together, fixing them in position in a compounded
thermoplastic and mineral-containing resin pellet, heated at
temperatures above 400.degree. F., and extrusion coated in-line on
a single piece of equipment an extrusion laminated on a single
piece of equipment at high speeds from about 100 FPM (feet per
minute) up to about 3,500 FPM on paper rolls up to and over from
about 30'' to about 140'' wide. The mineral-containing layer resin
is extruded as a pre-mixed or master batch pellet, and as such the
layer maintains its original integrity after extrusion. Therefore,
unlike aqueous or emulsion coatings, no mixing is required prior to
coating, and drying is not required during production at the point
of printing and converting. The mineralized polyolefin or polymer
layer provides additional benefits, such as high speed heat sealing
and improved barrier performance. Additional benefits may include
an excellent surface for the application of room temperature and
hot melt adhesives when forming a package and high levels of
moisture, oil, and fatty acid barrier performance.
[0031] The fiber component of the repulpable composite may comprise
softwood fibers, hardwood fibers, or a mixture thereof. For
example, the paper substrate may comprise from about 5% to about
95% (such as from about 25% to about 90%) softwood fibers and from
about 5% to about 95% (such as from about 25% to about 90%)
hardwood fibers. Paper substrates may also have, for example, a
basis weight of from about 30 to about 200 lbs/3000 sq. ft and a
caliper (thickness) of from about 0.006'' to about 0.048''.
[0032] During paper repulping and processing, the fibers are
subjected to a cleansing and filtering process provided by one or
more screens, thus removing unwanted materials from the re-pulped
fiber. Screen plates are commonly designed to be either hole,
slotted, or contoured screens. The amount and type of rejected and
removed material can have an impact on screen cleanliness. If the
screens become clogged, they fail to function and must be cleaned,
creating expensive downtime during processing. The plates are
normally found one behind another with an A plate having the
smallest perforations, an intermediary B plate, and often a C plate
having the largest perforations. Because of the size and
conformation of plastic coating fragments generated during
repulping, the plastic rejects clog and dirty the screening system,
creating downtime and general inability to process efficiently.
However, mineral-containing layers create dense particles from
about 5 mm.sup.2 to about 0.01 mm.sup.2 Therefore, based upon
reject rates from about 10% to about 25% by weight of the starting
paper, the screen cleanliness efficiency achieved can be from about
60% to about 100%, including pressure screen devices. Further, the
pressure drop, expressed as Feed-Accept pressure, can range from
about 2 kPa to about 12 kPa on smooth, contoured, or heavily
contoured screens.
[0033] Post screen processing includes centrifugal cleaning of the
screen accepts. This pulp cleaning process uses fluid pressure to
create rotational fluid motion in a tapered cylinder, causing
denser particles to move outside faster than lighter particles.
During cleaning, good fiber yields are carried inward and upward to
the accepted stock inlet. Impurities such as dirt, metals, inks,
sand, and any impurities are held in the downward current and
removed from the bottom of the cleaner. Mineral-containing layer
impurities found in fiber accepts and rejects have a density of
from about 1.01 g/cm.sup.3 to about 4.25 g/cm.sup.3 Because the
particles have large density differences from water, and size
characteristics, the particles are effectively removed and cleaned
from the accepts during cleaning. The mineral-containing impurities
process out of the fiber accepts efficiently in High Density,
Forward, and Through Flow cleaners, the cleaners having a diameter
of from about 70 mm to about 400 mm. Further, these particles
process out of fibers having reject rates on or about 0.1-1% to
about 5-30%. Additionally, because some particles are typically
somewhat spherical in shape (CwAp) they separate more efficiently
during centrifugal cleaning. Finally, because the particles are
smaller in size and generally dense, they can often achieve a
removal efficiency of from about 50% to about 95% by mass, particle
sizes of from about 150 microns to about 0.05 microns using
singularly or in combination, specific gravity activated
centrifugal cleaners, flotation washers, and ultra-dispersion
washing, the repulpable and recyclable composite material having a
pulper consistency of from about 3% to about 30%, pulping
temperatures of from about 100.degree. F. to about 200.degree. F.,
and pulping times of from about 10 minutes to about 60 minutes,
with pulping pH from about 6 to about 9.5.+-.0.5. Process pressure
screens can have holes from about 0.050'' to about 0.075'' with
slots from about 0.006'' to about 0.020''.
[0034] Table 1, below, illustrates estimated repulpability ranges
of a composite containing paper layer(s) combined with mineralized
layer(s). The chart is also applicable when using paper layer(s)
fiber fine content from about 0.5% to 60% by weight of the paper.
This data is congruent using various pulping batch and continuous
pulping methods including low consistency continuous, rotor
de-trashing, drum pulping having 9-20 RPM, high consistency drum
pulping, and drum pulping containing 4 mm to 8 mm holes, pulping
consistency from about 3% to about 20%, also, using disk, pressure,
and cylindrical screen types with hole type screen openings from
about 0.8 mm to about 1.5 mm and slot and contoured type openings
from about 0.1 mm to about 0.4 mm, further including coarse to fine
screen holes and slots from about 0.150 mm to about 2.8 mm, and
screen rotor circumference speeds from about 10 meters/second (m/s)
to about 30 m/s.
TABLE-US-00001 TABLE 1 Composite Repulpability Mineral Thermo-
Screen Cal- Content of plastic Yield Inor- Total iper lbs/ Barrier
Bonding (Ac- ganic Overall (in.) 3 msf Layer(s) Agent cepts) Matter
Recovery 0.010 136 30%-65% 30%-70% 60%-90% 1%-40% 70%-95% 0.012 157
30%-65% 30%-70% 60%-90% 1%-40% 70%-98% 0.014 172 30%-65% 30%-70%
60%-90% 1%-40% 70%-98% 0.016 190 30%-65% 30%-70% 60%-90% 1%-40%
70%-98% 0.018 208 30%-65% 30%-70% 60%-90% 1%-40% 70%-98% 0.020 220
30%-65% 30%-70% 60%-90% 1%-40% 70%-98% 0.022 241 30%-65% 30%-70%
60%-90% 1%-40% 70%-98% 0.024 259 30%-70% 60%-90% 1%-40% 70%-98%
0.026 268 30%-70% 60%-90% 1%-40% 70%-98% 0.028 276 30%-70% 60%-90%
1%-40% 70%-98% 0.030 286 30%-70% 60%-90% 1%-40% 70%-98%
[0035] Note: Percentages are "by weight" of the total composition.
MSF is "thousand square feet." % of inorganic matter is based upon
industry standard ash tests. Repulpability data per Tappi and Fibre
Box Association industry standard testing and Georgia Tech IPST
reporting.
[0036] Various diatomaceous earth mineral fillers and pigments are
available for use within the repulpable mineral-containing layer
within the composite structure including mica, silica, clay,
kaolin, calcium carbonate, dolomite, and titanium dioxide to name a
few. The fillers offer improved performance for barrier, opacity,
increased stiffness, thermal conductivity, and strength. Fillers
are normally less expensive than polymers and are therefore a very
economical component of the polymer layer. The most commonly used
mineral fillers have densities in the range of 2.4 g/cm.sup.3 to
4.9 g/cm.sup.3. Most polymers have densities in the range of 0.8
g/cm.sup.3 to 1.85 g/cm.sup.3 and many can be used as thermoplastic
bonding agents.
[0037] Filler particles can vary in size and shape. Size can vary
from 0.1 micron to 10.0 micron mean particle size. An example of
very fine mineral particles include nano-precipitated calcium
carbonate which are less than 100 nanometers in size. Ultrafine
nanoparticles can range from 0.06 microns to 0.15 microns. These
ultrafine particles are useful for controlling rheological
properties such as viscosity, sag, and slump. Mineral filler
particles can have various shapes including e.g. spheres, rods,
cubes, blocks, flakes, platelets, and irregular shapes of various
proportions. The relationship between the particles' largest and
smallest dimensions is known as aspect ratio. Together, aspect
ratio and shape significantly impact the particles' effect in a
composite polymer matrix. In yet other examples, particle hardness
relates to coarseness, color to layer cosmetics and opacity.
Particle morphology suited for the present embodiments are
primarily, but not limited to, the cube and block shapes of salt
and calcite having the characteristics shown in Table 2, below.
Examples of cubic structures include calcite and feldspar. Examples
of block structures include calcite, feldspar, silica, barite, and
nephelite.
TABLE-US-00002 TABLE 2 Mineral Physical Properties PARTICLE CLASS
CUBE BLOCK Type Cubic, Prismatic, Tabular, Prismatic, Rhombohedral
Pinacoid, Irregular Aspect/Shape Ratios: Length -1 1.4-4 Width -1 1
Thickness -1 1-<1 Sedimentation esd esd Surface Area Equivalence
1.24 1.26-1.5
[0038] Mineral particles also often have higher specific gravity
than polymers. Therefore, the density increases cost through
elevated weight. Many particles are surface treated with fatty
acids or other organic materials, such as stearic acid and other
materials to improve polymer dispersion during compounding. Surface
treatments also affect dry flow properties, reduce surface
absorption, and alter processing characteristics. The specific
gravity range potential of the minerals used in the present
embodiments including pigments are from about 1.8 to about 4.85
g/cm.sup.3.
[0039] It is advantageous to disperse fillers and pigments (which
provide opacity and whiteness to the polymer composite) effectively
in order to obtain good performance. For fillers, impact strength,
gloss, and other properties are improved by good dispersion. For
pigments, streaking indicates uneven dispersion, whereas a loss in
tinting strength may be observed if the pigment is not fully
de-agglomerated. Agglomerates act as flaws that can initiate crack
formation and thus lower impact strength. In the present
embodiments, agglomerates are preferably less than about 30 microns
to preferably less than about 10 microns in size.
[0040] Resin and composite extrudate sensitivity to heat becomes
important during extrusion coating and extrusion lamination
production. Small alterations during processing have an outsized
impact upon pre- and post-extrusion results. Table 3 is a sample,
but not limited to, extrusion coating production ranges for
identified mineral-filled resins. In Table 3, the melt index
measurements were stated under the guidelines of ASTM method
D1238-04, and the density measured under the guidelines of ASTM
standard method D1501-03.
TABLE-US-00003 TABLE 3 Operating Parameters, Mineralized Composite
Resins, Monolayer, Coextrusion and Multilayer Mineral-Containing
Composites, to Fiber-Containing Layers Extruder #2-#6 Maximum
ranges Coextrusion or Plus & Minus as separate a % of stated
Comments below Extruder #1 downstream value or stated do not
represent ROLL Monolayer units value limitations RESIN Earth
Coating Earth Coating SUPPLIER Standridge Color Standridge Color
GRADE TBD TBD NUMBER MELT FLOW- EST: EST: 4 g IO/min to
Interspersed and Carrier 16 g/10 min 16 g/10 min 16 g IO/min
non-interspersed Resin(s)/bonding agent COMPOUND 1.25 g/cm.sup.3
1.25 g/cm.sup.3 1.01-4.90 g/cm.sup.3 Molecular DENSITY weight from
(Mz 150,00 to 300,000) MINERAL 40% 40% General mineral Interspersed
and CONTENT content 15-60% non-interspersed by weight MELT
590.degree. F TBD .+-.20% TEMPERATURE (307.degree. C) DESIRED
1600-2200 psi TBD 1200-2500 psi From 1 to 6 BARREL extruders PRESS.
Composite Melt 2-12 g/ 2-12 g/ 2 g/10 min- Interspersed and Flow 10
min 10 min 14 g/10 min non-interspersed Air Gap 8'' 4''- 4''- 12''
16'' Die Gap 0.025''- 0.025''- 0.020''- From 1 to 6 0.030'':
0.040'' 0.050'' Coextrusion Monolayer and Initial Settings Maximum
Settings Die Maximum Coextrusion or Barrel Zones Adjustment Zone
Adjustment Die separate Barrel Zones Zone downstream #2- #6
Co-layers TEMPERATURE SETTINGS Melt Temperature 590.degree. F. Up
to .+-.25% BARREL ZONE 405.degree. F. Up to .+-.35% Die Zone 1
585.degree. F. .+-.25% #1 BARREL ZONE 540.degree. F. Up to .+-.35%
Die Zones 2-10 595.degree. F. .+-.25% #2 (as applicable to
equipment) BARREL ZONE 575.degree. F. Up to .+-.35% Die Zone 11
585.degree. F. .+-.25% #3 (as applicable to equipment) BARREL ZONE
590.degree. P Up to .+-.35% #4 BARREL ZONE 590.degree. P Up to
.+-.35% #5 Other barrel 590.degree. P Up to .+-.35% Other die zones
Up to .+-.35% Zones, if if applicable applicable on specific
equipment
[0041] Molecular chains in crystalline areas are arranged somewhat
parallel to each other. In amorphous areas they are random. This
mixture of crystalline and amorphous regions is essential to the
extrusion of good extrusion coatings. The crystals can act as a
filler in the matrix, and so can mineralization, improving some
mechanical properties. A totally amorphous polyolefin would be
grease-like and have poor physical properties. A totally
crystalline polymer would be very hard and brittle. High-density
polyethylene (HDPE) resins have molecular chains with comparatively
few side chain branches. Therefore, the chains are packed closely
together. Polyethylene, polypropylene, and polyesters are
semi-crystalline. The result is crystallinity up to 95%.
Low-density polyethylene (LDPE) resins have, generally, a
crystallinity ranging from 60% to 75%, and linear low-density
polyethylene (LLDPE) resins have crystallinity from 60% to 85%.
Density ranges for extrusion coating resins include LDPE resins
that range from 0.915 g/cm.sup.3 to 0.925 g/cm.sup.3 LLDPE resins
have densities ranging from 0.910 g/cm.sup.3 to 0.940 g/cm.sup.3
and medium-density polyethylene (MDPE) resins have densities
ranging from 0.926 g/cm3 to 0.940 g/cm.sup.3 HDPE resins range from
0.941 g/cm.sup.3 to 0.955 g/cm.sup.3. The density of PP resins
range from 0.890 g/cm.sup.3 to 0.915 g/cm.sup.3.
[0042] Addition of a mineral filler to the polymer results in a
rise in viscosity. The addition of filler may also change the
amount of crystallinity in the polymer. As polymer crystals are
impermeable to low molecular weight species, an increase in
crystallinity also results in improved barrier properties, through
increased tortuosity. This effect is expected to be prevalent for
fillers that induce a high degree of transcrystallinity. Some
minerals can change the crystallization behavior of some
thermoplastics and thus the properties of the polymer phase are not
those of virgin material, providing novel characteristics during
processing and in the performance of the finished composite
structure. Thermoplastics crystallize in the cooling phase and
solidify. Solidification for semi-crystalline polymers is largely
due to the formation of crystals, creating stiffer regions
surrounding the amorphous area of the polymer matrix. When used
correctly, mineral fillers can act as nucleating agents, normally
at higher temperatures. This process can provide mechanical
properties in the polymer composite favorable to high barrier
performance and adhesion to fiber surfaces without a detrimental
effect on heat sealing characteristics. Minerals can begin to
significantly affect crystallinity when used from about 15% to
about 70% by weight of the polymer composite. Some of the factors
influencing mechanical adhesion to paper include extrudate
temperature, oxidation, and penetration into the fibers. Mineral
onset temperatures of the polymer extrudate influence cooling rate
upon die exit to the nip roller, which can be adjusted by the
extruder air gap setting. Other key factors include the mass of the
polymers of the polymer interface layer. The crystalline onset
temperatures vary, however, examples are shown in Table 4,
below.
TABLE-US-00004 TABLE 4 Selected Polymers with Estimated Mineral
Onset Temperatures Unfilled Polypropylene 120-122.degree. C.
Calcium Carbonate 120-125.degree. C. Dolomite 120-131.degree. C.
Talc 120-134.degree. C. Silica 120-122.degree. C. Mineral Fiber
120-122.degree. C. Mica 120-124
[0043] Further, homogeneous blends of solid olefin polymers with
varying densities and melt indexes can be mixed within the mineral
composite layer, either interspersed or noninterspersed through
coextrusion. The mineral-containing composite layer can be applied
and bonded substantially and continuously on at least a
fiber-containing layer using extrusion or extrusion lamination,
including blown film, cast, or extrusion coating methods. Polymer
content of the mineral-containing layer can be used as a tie layer
for interspersed and non-interspersed constructions as well as
particle bonding agents within each individual layer. These bonding
agents or tie layers can include individually, or in mixtures,
polymers of monoolefins and diolefins, e.g. polypropylene,
polyisobutylene, polybut-1-ene, poly-4-methylpent-1-ene,
polyvinylcyclohexane, polyisoprene or polybutadiene, homogeneous
mettallocene copolymers, and polymers of cycloolefins, e.g.
cyclopentene or norbornene, polyethylene, cross-linked
polyethylene, ethylene oxide and high density polyethylene, medium
molecular weight high density polyethylene, ultra heavy weight high
density polyethylene, low density polyethylene, very low density
polyethylene, ultra low density polyethylene; copolymers of
monoloefins and diolefins with one another or with other vinyl
monomers, e.g. ethylene/propylene copolymers, linear low density
polyethylene, and blends thereof with low density polyethylene,
propylene but-1-ene, copolymers ethylene, propylene/isobutylene
copolymers, ethylene/but-1-ene copolymers, ethylene/hexene
copolymers, ethylene/octene copolymers, ethylene/methylepentene
copolymers, ethylene/octene copolymers, ethylene/vinyelcyclohexane
copolymers, ethylene/cycloolefin copolymers, COC, ethylene/I-olefin
copolymers, the I-olefin being produced m situ; propylene/butadiene
copolymers, isobutylene/isoprene copolymers,
ethylene/vinylcyclohexene copolymers, ethylene vinyl acetate
copolymers, ethylene/alkyl methacrylate copolymers,
ethylene/acrylic acid copolymers or ethylene/acrylic acid
copolymers and salts thereof (ionomers) and terapolymers of
ethylene with propylene and diene, such as, for example, hexadiene,
dicyclopentadiene or ethylidenenorbornene; homopolymers and
copolymers that may have any desired three dimensional structure
(stereo-structure), such as, for example, syndiotactic, isotactic,
hemiisotactic or atactic stereoblock polymers are also possible;
polystyrene, poly methylstyrene, poly alpha-methylstyrene, aromatic
homopolymers and copolymers derived from vinylaromatic monomers,
including styrene, alpha-methylstyrene, all isomers of vinyl
toluene, in particular p-vinyltoluene, all isomers of ethylstyrene,
propylstyrene, vinylbiphenyl, vinylnaphthalene and blends thereof,
homopolymers and copolymers of may have any desired three
dimensional structure, including syndiotactic, isotactic,
hemiisotactic or atactic, stereoblock polymers; copolymer,
including the above mentioned vinylaromatic monomers and commoners
selected from ethylene, propylene, dienes, nitriles, acids, maleic
anhydrides, vinyl acetates and vinyl chlorides or acryloyl
derivatives and mixtures thereof--for example styrene/butadiene,
styrene/acrylonitrile, styrene/ethylene (interpolymers)
styrene/alkymethacrylate, styrene/butadiene/alkyl acrylate,
styrene/butadiene/alkyl methacrylate, styrene/maleic anhydride,
styrene copolymers; hydrogen saturated aromatic polymers derived
from by saturation of said polymers, including
polycyclohexylethylene; polymers derived from alpha,
beta-unsaturated acids and derivatives; unsaturated monomers such
as acrylonitrile/butadiene copolymers acrylate copolymers, halide
copolymers and amines from acyl derivatives or acetals; copolymers
with olefins, homopolymers and copolymers of cyclic ethers;
polyamides and copolyamides derived from diamines and dicarboxylic
acids and or from aminocarboxylic acids and corresponding lactams;
polyesters and polyesters derived from dicarboxylic acids and dials
and from hydroxycarboxylic acids or the col Tesponding lactones;
blocked copolyetheresters derived from hydroxyl terminated
polyethers; polyketones, polysulfones, polyethersulfones, and
polyetherketones; cross-linked polymers derived from aldehydes on
the one hand phenols, ureas, and melamines such as
phenol/formaldehyde resins and cross-linked acrylic resins derived
from substantial acrylates, e.g. epoxyacrylates, urethaneacrylates
or polyesteracrylates and starch; polymers and copolymers of such
materials as polybutylene succinate, polymers and copolymers of
N-vinylpyrroolidone such as polyvinylpyrrolidone, and crosslinked
polyvinylpyrrolidone, ethyl vinyl alcohol. More examples of
thermoplastic polymers suitable for the mineral-containing
composite include polypropylene, high density polyethylene combined
with MS0825 Nanoreinforced POSS polypropylene, thermoplastic
elastomers, thermoplastic vulcinates, polyvinylchloride, polylactic
acid, virgin and recycled polyesters, cellulosics, polyamides,
polycarbonate, polybutylene tereaphthylate, polyester
elastomers,thelmoplastic polyurethane, cyclic olefin copolymer;
biodegradable polymers such as Cereplast-Polylactic acid,
Purac-Lactide PLA, Nee Corp PLA, Mitsubishi Chemical Corp GS PLS
resins, Natureworks LLC PLA, Cereplast-Biopropropylene, Spartech
PLA Rejuven 8, resins made from starch, cellulose, polyhydroxy
alcanoates, polycaprolactone, polybutylene succinate or
combinations thereof, such as Ecoflex FBX 7011 and Ecovio L Resins
from BASF, polyvinylchloride and recycled and reclaimed polyester
such as Nodax biodegradable polyester by P & G.
[0044] The mineral-containing layer can include coupling agents
from about 0.05% to about 15% of the weight of the
mineral-containing layer. The agents aid in the mixing and the
filling of the mineral into the polymer matrix. Functional coupling
groups include (Pyro-) phosphato, Benzene sulfonyl and ethylene
diamino. These can be added to thermoplastics including
polyethylene, polypropylene, polyester, and ethyl vinyl alcohol,
aluminate, siloxane, silane, an lino, malice anhydride, vinyl and
methacryl. The results of these combinations improve adhesion to
fibers, heat seal strength, heat seal activation temperatures,
surface energy, opacity, and cosmetics. Mineral content can
include, but is not limited to, wollanstonite, hydrated and
non-hydrated, magnesium silicate, barium sulfate, barium ferrite,
magnesium hydroxide, magnesium carbonate, aluminum trihydroxide,
magnesium carbonate, aluminum trihydroxide, natural silica or sand,
cristobalite, diaonite, novaculite, quartz tripoli clay calcined,
muscovite, nepheliner-syenite, feldspar, calcium sulfate-gypsum,
terra alba, selenite, cristobalite, domite, silton mica, hydratized
aluminum silicates, coke, montmorillonite (MMT), attapulgite (AT)
carbon black, pecan nut flour, cellulose particles, wood flour, fly
ash, starch, TiO.sub.2 and other pigments, barium carbonate, terra
alba, selenite, nepheline-syenite, muscavite, pectolite,
chrysotile, borates, sulfacates, nano-particles of the above from
0.01 to 0.25 micron particle size, and precipitated and ground
calcium carbonate. Among, but not limited procedures generally
involving the use of polymerization initiators of catalysts for the
polymerization of butene-I monomer to polymers of high molecular
weight, preferably catalytic systems used in such procedures are
the reaction products of metal alkyl compounds such as aluminum
triethyl, and a heavy metal compound, such as the trihalides of
Groups IV-VI metals of the periodic table, e.g. titanium, vanadium,
chromium, zirconium, molybdenum and tungsten. The formation of
polymers exhibiting substantial isotactic properties as wells as
the variations in the molecular weight and the nature of the
polymerization catalyst, co-reactants, and reaction conditions.
Suitable, but not limited to, isotatic polybutylenes are relatively
rigid at normal temperatures but flow readily when heated, and they
most preferably, should show good flow when heated, expressed in
melt:flow. Applicable isotatic polybutylenes should show a melt
flow of from 0.1 to 500, preferably 0.2 to 300, more preferably
from 0.4 to 40, most preferably 1 to 4. Other polymers expressed
within the contents of the present specification should also be
considered within these parameters.
[0045] Regarding the mineral-containing composite layer, upon
substantially and continuously bonding to the fiber-containing
using extrusion coating or extrusion lamination techniques, the
layer of which can then be used to form a laminated structure of
which the mineral-containing layer can be used as a peel coat onto
a desired backing material. The best peel seal, for example, to the
mineral-containing layer of the composite, may be selected from
poly-4-methyl pentene, nylon, high-density polyethylene (HDPE),
aluminum foil, polycarbonate polystyrene, polyurethane, polyvinyl
chloride, polyester, polyacrylonitrile, polypropylene (PP), and
paper. An example extrusion process can be accomplished with a
screw or pneumatic tube. Sometimes the mineralized polymers can be
combined with such materials as plasticizers lubricants,
stabilizers, and colorants by means of Banbury mixers. The
resulting mix is then extruded through rod shaped dies and chipped
into pellets. Pelletized mineralized polymer can then enhance the
mineral and other content by "letting down" the resin pellet mix
with inline or offline mixing capability before being fed into the
end of a, for example, screw-type extruder, heated, and mixed into
a viscous fluid or semi-fluid in the extruder barrel for further
processing to the die. Further, when properly dispersed the
interaction between the mineral particles and the polymer content
without covalent bonding, results in improved van der Waals forces
that provide attraction between the materials. This interaction
results in some adhesion in the composite during extrusion,
resulting in an absorbed polymer layer on the filler surface. These
considerations combined with the unique attributes of the mineral
content dispersed within the polymeric matrix of both monolayer and
multilayer mineral composite layers impact the application of heat
that initiates the melting of semi-crystalline polymers, causing
the polymer molecules to better diffuse across the interface. Given
sufficient time, the diffused polymers form entanglements at the
inter-facial layer. This effect is possible at extrusion line
speeds from up to about 100 FPM and extrusion lamination up to
about 3,500 FPM, using semi-crystalline mineralized resin blends
with extrusion equipment die and barrel zone temperatures from
about 540 degrees to about 615 degrees F. Because of improved
mineral thermal properties, oxidation of the extrudate upon exiting
the die but before fiber contact improves from about I 0-50%, thus
greatly strengthening fiber bonding characteristics under normal
equipment operating conditions.
[0046] Molecular weight ranges of the polymer bonding agent
component of the mineral containing layer are from about Mw 10,000
to about Mw 100,000. Further, about 10%-70% of the polymer bonding
agent may have a branching index (g') of about 0.99 or less as
measured at the Z-average molecular weight (Mz) of the polymer.
Some, part, or all of the mineral containing layer polymer bonding
agent is preferred but not required to have an isotactic run length
of from about I to about 40. Further, the polymer bonding agent of
the mineral containing layer has a shear rate range of from about
Ito about 10,000 at temperatures from about 180.degree. C. to about
410.degree. C.
TABLE-US-00005 TABLE 5 Particle characteristics of CaCO.sub.3
Particle Coating Fatty Acids Including Stearates Hunter Reflectance
(Green) 91-97% Hunter Reflectance (Blue) 89-96% Mohs Hardness
2.75-4.0 pH in Water, 5% Slurry, 23.degree. C. 8.5-10.5 Resistance
in Water, ohms, 23.degree. C. 5,000-25,000 ASTM DI 119 Max % on 325
Mesh 0.05-0.5 Volume Resistivity @ 25.degree. C. 10.sup.9-10.sup.11
ohms pH 8.5-10.5 lard Heat of Formation, Ca CO.sub.3 from
288.45-288.49 Kg-cal/mole its Elements 25.degree. C. Standard Free
Energy of Formation, 269.53-269.78 Kg-cal/mole Ca CO.sub.3 from its
Elements 25.degree. C. Specific Heat (between O to 100.degree. C.)
0.200-0.214 Heat Conductivity 0.00071 g ca/sec cm.sup.2 1 cm thick@
25.degree. C. Coefficient of Linear Expansion C = 9 .times.
10.sup.6@ 25 to 100.degree. C. C = 11.7 .times. 10@ 25 to
100.degree. C.
[0047] Also, nano-cellulose can be used in the mineral-containing
composite layer having a crystalline content from about 40%-70%,
including nano-fibrils, micro-fibrils, and nanofibril bundles,
having lateral dimensions from about 0.4-30 nanometers (nm) to
several microns, and highly crystalline nano-whiskers from about
100 to 1000 nanometers. Nanocellulose fiber widths are from about
3-5 nm and from about 5-15 nm, having charge densities from about
0.5 meq/g to about 1.5 meq/g, with the nano-cellulose having a
stiffness from about an order of 140-220 GPa and tensile strength
from about 400-600 MPa.
[0048] The mineral-containing interspersed or non-interspersed
polymer composite layer can be substantially and continuously
directly bonded to a fiber surface or to the fiber surface
interface adhesive layer using extrusion coating or extrusion
lamination. Further, the fiber containing layer can contain
inorganic mineral coatings and fillers, e.g. clay, kaolin, CaC03,
mica, silica, TiO.sub.2 and other pigments, etc. Other materials
found in the fiber-containing layer include vinyl and polymeric
fillers and surface treatments such as starch and latex. Preferred
characteristics of the fiber-containing layer bound to the
mineral-containing layer include, but are not limited to, a
smoothness range of about 150 to about 200 Bekk seconds, and an ash
content from about 1% to about 40% by weight. Also, in this
example, the fiber-containing layer coefficient of static friction,
.mu., is from about 0.02 to about 0.50. Identified cellulose within
the fiber-containing layer preferably has a thermal conductivity
from about 0.034 to about 0.05 W/mK. If using air-laid paper or
non-woven fibers, the fiber content is preferably from about 40% to
about 65% of the layer by weight. Other preferred, but not
limiting, characteristics of the fiber-containing layer are shown
in Table 6, below.
TABLE-US-00006 TABLE 6 Fiber Layer Characteristics Fiber Aspect
Ratio (Average) 5-100 Fiber Thickness (Softwood) 1.5-30 mm Fiber
Thickness (Hardwood) 0.5-30 mm Filled Fiber Content 1% to 30% Fiber
Density 0.3-0.7 g/cm2 Fiber Diameter 16-42 microns Fiber Coarseness
16-42 mg/100 m Fiber Pulp Types Mechanical, Thermo-Mechanical,
Chemi- (Single- to Triple-Layered) Thermo-Mechanical, and Chemical
Permeability 0.11-110 m.sup.2 .times. 10.sup.15 Hydrogen Ion
Concentration 4.5-10 Tear Strength (Tappi 496, 56-250 402) Tear
Resistance (Tappi 414) M49-250 .sup. Moisture Content 2%-18% by
Weight
[0049] Coextrusion methods provide the possibility for
non-interspersed contact layers within the mineral-containing
layer. Based on performance and structural requirements, the
finished composite structures can contain separate layers in the
composite that can vary based on types of mineral and amount of
mineral content per layer, degrees of amorphous and crystalline
content per layer, and type of polymer resin and resin mixes per
layer. The more extruders feeding a common die assembly, the more
layered options become available to the noninterspersed
mineral-containing layer. The number of extruders depends on the
number ofdifferent materials comprising the coextruded film. For
example, a non-interspersed mineral containing composite may
comprise a three-layer to six-layer coextrusion including a barrier
material core that could be, for example, a high density
polyethylene and low density polyethylene mix having a 25% to 65%
mineral content by weight in the first base layer, this layer
making contact with the fiber surface. Subsequent layers may
contain differing mineral contents, neat LDPE, or polypropylene.
Another example is a six-layer coextrusion including a bottom layer
of LDPE, a tie-layer resin, a 20% to 65% mineral-containing
polypropylene barrier resin, a tie-layer, and an EVA copolymer
layer, and a final layer of polyester. Any mineral containing
barrier layer according to the present embodiments may have a basis
weight from about 4 lbs/3 msf to about 60 lbs/3 msf, a density from
about 1.10 g/cm.sup.3 to about 1.75 g/cm.sup.3, and/or a caliper
from about 0.30 mil to about 3 mil. Tie-layers often are used in
the coextrusion coating of multiple layer constructions where
mineral-containing polymers or other resins would not bond
otherwise, and tie-layers are applied between layers of these
materials to enable desired adhesion. Another example multilayer
film construction is 25%-65% mineral content LLDPE/tie-layer/EVOH
barrier/tie-layer/EV A Interspersed, e.g. monolayer, and
noninterspersed, e.g. multilayer, coextrusions can comprise from
one to six layers of the mineral containing layer substantially and
continuously bonded across the surface of a fiber-containing layer.
Layers can be designed to improve hot tack, heat-sealability, seal
activation temperature, and extrudate adhesion to fiber, mineral
enhancement of barrier performance, surface energy, hot and cold
glue adhesion improvements, etc.
[0050] Table 7, below, shows example layer constructions (not
limited to) found in the mineral-containing resin and extrusion
coated or laminate composite structure. The preferred single layer
ranges contain from about 0% to about 65% by weight mineral
content, from 25%-80% amorphous to 25%-80% crystalline structure by
weight, and 25%-65% cellulose, nanocellulose, or nano-minerals by
weight. Also, the mineral content of the mineral-containing
layer(s) may comprise different fillers with different densities,
size, and shape depending upon the desired outcome of the final
composite structure.
TABLE-US-00007 TABLE 7 Examples of Non-Interspersed (Multilayered)
Mineral Composite Layers Layer Structure Example 1 Example 2
Example 3 Example 4 Example 5 Example 6 Monolayer LDPE HDPE
LDPE-HDPE resin LDPE-MMW LLDPE- PLA-bio (1) blend HDPE resin LDPE
resin derived blend blend starch based resm blend Monolayer Bio-
LDPE-bio LDPE-LLDPE-bio LDPE-HDPE- PP-bio ULDPE- (2) derived,
derived derived starch blend LLDPE blend derived starch HDPE-
starch starch based bio polymer polymer polymer derived blend blend
blend starch polymer blend 3-layer HDPE- HDPE-PP HDPE-PET LDPE-PP
LLDPE-PET EVA- LDPE LDPE 4-layer EVA- HDPE- Biaxially oriented
Oriented EVA-PE- PVC- ethylene EVA- homopolypropylene-
polypropylene- MMWHDPE- ABS-PC vinyl Ionomer polyester- HDPE-PE-
oriented Nylon acetate resm- polypropylene-PE metallized
polypropylene EEA- Polyamides- PET ethylene acrylic acid- HDPE- EAA
ethylene acrylic acid
[0051] Additionally, ifrelative clarity is desired in the
mineral-containing composite layer the following resins are
possible, but not limiting, bonding agents for these materials:
carboxy-polymethyelene, polyacrylic acid polymers and copolymers,
hydroxypropylcellulose, cellulose ethers, salts for poly(methyl
vinyl ether-co-maleic anhydride), amorphous nylon, polyvinyl
chloride, polymethyl pentene, methyl
methacrylate-acrylonitrile-butadiene-styrene,
acrylonitrile-styrene, poly carbonate, polystyrene, poly
methylacrylate, polyvinyl pyrrolidone, poly
(vinylpyrrolidone-co-vinyl acetate), polyesters, parylene,
polyethylene naphatalate, ethylene vinyl alcohol, and poly lactic
acids containing from about 10% to about 65% mineral content.
Various mineral-containing layer polymer and mineral content can be
determined based upon performance and content requirements
considering the parameters shown in Table 7, above. Branched,
highly branched, and linear polymer combinations are possible in
all composite layer constructions. Examples are shown in Table 7
(not limited to combinations within the table) of the interspersed
and non-interspersed mineral-containing layer constructions, not
including tie layers. Layer combinations depend on coextrusion die
design, flow properties, and processing temperature, allowing for
coextrusion fusion layers and/or subsequently extrusion laminating
or laminating the layers into the final mineral-containing
composition, of which individual (noninterspersed) or total
combination of layers have by weight mineral content of about
20%-65%. Layers can be uniaxially or biaxially oriented (including
stretching) from about 1.2 times to about 7 times in the machine
direction (MD) and from about 5 times to about 10 times in the
cross-machine (transverse) direction (CD), and stretched from about
10% to about 75% in both the MD and CD directions. Generally,
although without limitation, polyolefin mineral content bonding
agents have number average molecular weight distributions (Mn) of
from about 5,500 to about 13,000, weight average molecular weight
(Mw) of from about 170,000 to about 490,000, and Z average
molecular weight (Mz) of from about 170,000 to about 450,000. A
coextruded mineral-containing layer may differ in molecular weight,
density, melt index, and/or polydispersity index within the
finished layer structure. The polydispersity index is the weight
average molecular weight (Mw) divided by the number average
molecular weight (Mn). For example only, and without limitation,
the mineral-containing layer may have a Mw/Mn ratio of from about
6.50 to about 9.50. Using wet or dry ground CaCO.sub.3 as an
example, it can be surface treated at levels from about 1.6 to
about 3.5 mg surface agent/m.sup.2 of CaCO.sub.3. The surface
treatment can be applied before, during, or after grinding. Mean
particle sizes range from, without limitation, about 0.7 microns to
about 2.5 microns, having a top cut from about d98 of 4-15 microns,
and a surface area of from about 3.3 m.sup.2/g to about 10.0
m.sup.2/g. For improved dispersion into the polyolefin bonding
agent, the CaCO.sub.3 mineral content can be coated with fatty
acids from between, without limitation, about 8 to about 24 carbon
atoms.
[0052] The preferred surface treatment range is about 0.6% to about
1.5% by weight of treatment agent or about 90%-99% by weight of
CaCO.sub.3. Polyolefin bonding agents having lower molecular
weights and high melt index provide improved downstream moisture
barrier characteristics. Preferred mineral layer content could
include finely divided wet ground marble with 65% solids in the
presence of a sodium polyacrylate dispersant, dried, and surface
treated, and also dispersant at 20% solids, dried, and surface
treated.
[0053] Testing methods for measuring moisture vapor transmission
rates and water vapor transmission rates (MVTR/WVTR) often involve
tropical conditions (100.degree. F. and 90% RH) according to TAPPI
Test Method T-464, orienting the barrier coating toward the higher
humidity of the chamber atmosphere, when it is present on the
surface. For water resistance, the standard short (2 minute) and
long (20 minute) Cobb test is often used. For oil, two tests are
commonly used. The first is the 3M kit test per TAPPI T-559
standards, coating film weight as measured by TAPPi 410 standards.
The second is red dyed canola oil and castor oil exposure to the
coating surface using a 2-minute and a 20-minute Cobb ring.
[0054] Extruded mineral-containing interspersed and
non-interspersed composite layers of the present embodiments
demonstrate high barrier performance characteristics when
substantially and continuously bonded to fiber-containing layers.
The fiber-containing layers may include in their composition or
surface, but are not limited to, mineral and polymeric sizings,
surface treatments, coatings, and mineral fillers. Some advantages
of the non-fiber content of the fiber-containing layer include
improved fiber layer printability, ink hold out, dynamic water
absorption, water resistance, sheet gloss, whiteness, delta gloss,
pick strength, and surface smoothness. Often, mineral content
contained within or upon one or more opposing surfaces of the
fiber-containing layer can include, but is not limited to, clay,
calcined clay, or combinations thereof. The minerals are frequently
applied to the surface of the fiber-containing layer through a
blade or air coating process. Common mineral binding methods
include the use of protein systems such as a mixture of vinyl
acrylic/protein co-binders. Another non-limiting example is
tri-binder systems, e.g. SB/Pvac/Protein. Further, pigments such as
TiO.sub.2 can be included to improve whiteness characteristics. The
nature of the fiber layer's mineral and binder content can impact
the selection of the non-interspersed and interspersed
mineral-containing layer characteristics when bonded substantially
and continuously to one or more sides of the fiber-containing
layer(s), which comprise part of the composite structure. Examples
of non-fiber content in the fiber-containing layer include, but are
not limited to, 50%-95% of #1 clay or #1 fine clay, 3%-20% by part
calcined clay, 3%-40% by part Ti02, 2%-45% vinyl acrylic, and from
about 1% to about 35% protein binders, co-binders,
ortri-binders.
[0055] Also, the fiber-containing layer surfaces can have from
about 55% to about 88% TAPPI 452 surface brightness. The examples
shown in Table 8, below, illustrate acceptable, but not limiting,
fiber-containing layer characteristics for substantially and
continuously bonding to the mineral-containing layer. Surface
roughness values are based upon Parker Print Surf (.mu.m) and
Bendtsen (mls/min) per TAPPI T-479 (moderate pressure), TAPPI
T-538, and TAPPI 555 (print-surf method). Tear resistance per TAPPI
T-414 standards are expressed in millinewtons (mN). Surface
brightness is expressed per TAPPI 452. Burst strength is expressed
per TAPPI 403 standards. Bursting strength is reported as burst
ratio=bursting strength (lbs/in.sup.2/basis weight (lbs/ream).
Internal bond strength or interlayer strength of the
fiber-containing layer is an important characteristic as
represented by TAPPI T-403 and T-569. Preferred fiber-containing
layer internal strengths are, but are not limited to, from about
125 J/m2 to about 1150 J/m.sup.2. Further, fiber-containing layer
Z-direction tensile strength per TAPPI T-541 testing standard is
from about 45-50 Nm/g to about 950 Nm/g. Finally, preferred, but
non-limiting, fiber containing layer air resistance per TAPPI 547
is from about Oto about 1500 mls/min, as represented by the
Bendsten method.
TABLE-US-00008 TABLE 8 Fiber-Containing Layer Characteristics Fiber
Weight Tear Resistance Surface Burst Strength (lbs/3 msf) g/m2 (Mn)
Roughness (kPa) 40-75 60-110 400-700 2.0-5.5 140-300 .mu.m >75
110-130 650-700 2.0-3.5 175-400 .mu.m >115 180-190 1400-1900
100-2500 175-475 mls/min >130 205-215 1600-2200 100-2500 250-675
mls/min >200 315-330 1900-3200 100-2500 500-950 mls/min >300
460-195 500-4000 100-2500 700-1850 mls/min
[0056] Table 9, below, displays finished composite board barrier
performance ranges, but is not limited to, that of a composite
structure having from about 20% to about 70% mineral-containing
layer bonded to at least one side of a fiber-containing layer. The
mineral-containing layer can be either a dispersed monolayer or
non-interspersed coextrusion, for example.
TABLE-US-00009 TABLE 9 Barrier Values of Formed Composite Structure
Test Method TAPPI T441 TAPPI T464 TAPPI T410 TAPPI T559 Test Name
WVTRin Cobb Water Tropical Mineral layer Absorption Conditions Wgt
Grease Resistance units g/m2 3M Test Kit# Sample 2 minute 30 minute
g/100 lb/1000 Coated Uncoated # Fiber Layer Cobb Cobb g/m2 m.sup.2
g/m2 ft.sup.2 Side Side 1 Recycled .28 mil 0.22 -- 23.4 1.51 *12
**1- Fiber caliper 2 Virgin .20 mil 0.40 0.00 15.2 0.98 32.3 4.12
12 1- Fiber caliper 3 Recycled .20 mil 0.00 -- 18.6 1.20 3.45 12 1-
Fiber caliper 4 85-100% .20 mil 0.10 0.05 13.9 0.89 18.25 3.55 12
1- Recycled caliper Fiber 5 Virgin- .30 mil -- -- 7.58 0.49 12 1-
TMP caliper content 6 Clay coated .18 mil -- 0.45 7.13 0.46 7.5 12
1- 1 side- caliper bleached 7 Fiber 2- .18 mil 0.00 -- 9.31 0.6
6.44 12 1- side caliper bleached 8 Fiber 1 .18 mil 0.50 0.11 37.7
2.43 11.33 12 1- side, caliper bleached 9 Virgin .16 mil 0.05 0.11
15.0 0.97 3.94 12 1- Craft- clay caliper coated 10 Virgin .14 mil
0.00 0.10 14.1 0.91 28.1 3.89 12 1- Craft- clay thick coated 11
Clay .18 mil 0.00 0.05 13.0 0.84 6.2 12 1- coated, caliper
unbleached Kraft- 100% v1rgm 12 Solid .18 mil 0.00 0.00 9.49 0.61
52.2 5.5 12 1- Unbleached caliper Sulfate Note: 1 mil =
1/1000.sup.th of an inch
[0057] Table 10, below, shows the barrier performance of a formed
composite having a monolayer HDPE-PE mix with a density from about
0.925 gm/cm.sup.3 to about 0.960 g/cm.sup.3 and containing from
about 36% to about 45% mineral content by weight.
TABLE-US-00010 TABLE 10 Barrier Values of a Formed Composite
Structure, Interspersed (Mono), Mineral Containing Layer Fiber Type
WVTR in Tropical Cobb Water Conditions Mineral layer Absorption
100.degree. F./90% R.H. weight Unit g/m2 g/100 lb/1000 Sample 2-min
30-min g/m2 in.sup.2 g/m2 ft.sup.2 Recycled 0.2 0.1 16.7 1.08 24.9
5.09 Recycled 0.0 0.0 9.7 0.63 49.6 7.4 Virgin Kraft 0.0 0.1 11.1
0.72 32.8 6.73 Virgin Kraft 0.1 0.1 9.9 0.64 36.9 7.57 Virgin Kraft
0.0 0.1 8.7 0.56 36.2 7.42 Virgin Kraft 0.0 0.2 7.8 0.50 41.0 6.46
Virgin Kraft 26.1 5.35
[0058] Table 11, below, shows projected moisture barrier
performance (MVTR, WVTR) for the present embodiments, comparing a
coextruded mineral-containing layer bonded to a surface of a
fiber-containing layer, the mineral-containing layer having both a
monolayer and a multilayer (coextrusion) construction. The
fiber-containing layer in Table 11 lists Klabin virgin Kraft fiber.
However, the data is applicable to a range of both virgin and
recycled fiber surfaces to include similar various weights and
densities known in the art. Maximum MVTR via coextrusion is
projected to be about the values in Table 11 in mineral-containing
layers down to about 12 g/m.sup.2 layer weight. The data
illustrates two different MVTR values. The first value is
coextrusion. Coextrusion can provide superior results because of
the flexibility to alter the type of polymers used per layer,
density, branched or linear molecular nature, as well as
crystallinity, among others. Also, because of stress fracturing
found in more monolayer constructions as a result of bending,
scoring, and processing, performance improvements using coextrusion
are possible. The base layer in the coextrusion can be more dense
and crystalline, for example, than the outer layer, which is more
amorphous and light density and more linear, thus not as vulnerable
to stress fracture within the matrix, preventing percolation
through the layer. Other options for improving processing include
additives to the mineral-containing blend, which include, but are
not limited to, elastomers.
TABLE-US-00011 TABLE 11 Barrier Attributes of Mineral-Containing
Layer Bonded to Fiber-Containing Layer Based for Interspersed
(Monolayer) and Non-Interspersed (Coextruded) Composite Flat
Samples Full Case Mineral Layer Project Barrier Performance Table
Fiber Layer-Outer Layer Pre Score + Bed Post Score Weight Ethylene
Co-Polymer Mineral Layer--% Amorphous Uncoated Mineral Ranges
WVTR-Tropical WVTR WVTR Range Box board 38-65% gm/m2 day Variation
gm/m2 day Variation Ranges 20 pt. Klabin 2+ layer 5 to 13 0.20 11
to 17 0.2 15 gsm 50 gsm coex 1.22-1.41 g/cm3 25%-65% 1.22-1.36
g/cm3 25-70% 20 pt. Klabin Monolayer 8 to 22 0.2 14 to 25 0.2 15
gsm 50 gsm
[0059] FIG. I is a schematic side cross-sectional view of
amultilayer repulpable packaging composite material 20 according to
the present embodiments. The illustrated embodiment includes a
mineral-containing layer 22 having an outer or heat-sealable
surface 24. Figure IA is a detail view of the portion of Figure I
indicated by the circle IA-IA As shown in Figure IA, a plurality of
mineral particles 26 are interspersed within a bonding agent 28,
which may be a thermoplastic. With reference to FIG. 1, the
mineral-containing layer 22 may be substantially and continuously
bonded to a first surface 30 of a fiber-containing layer 32.
Another mineral-containing layer 22 may be substantially and
continuously bonded to a second surface 34 of the fiber-containing
layer 32, the second surface 34 being opposite the first surface
30. With reference to Figure IA, the fiber-containing layer 32
includes a plurality of fiber particles 36 interspersed within a
bonding agent 38, which may be a thermoplastic. The thermoplastic
bonding agent of either or both of the mineral-containing layer 22
and the fiber-containing layer 32 may comprise, for example and
without limitation, polyolefin, polyester, or any other
thermoplastic or polymer-containing resins.
[0060] The mineral-containing layer(s) 22 may include about 30% to
about 65% minerals, and the minerals may comprise any of the
minerals described throughout this specification and combinations
thereof. The mineral-containing layer(s) 22 may be adhered to the
fiber-containing layer 32 through coextrusion,
extrusion-lamination, or any other suitable method or process.
Extrusion-lamination may comprise a separately applied adhesive
between the mineral- and fiber-containing layers. The composite
material 20 illustrated in Figure I may advantageously be used as a
single or multiple corrugate liner(s) or medium(s) within a single
layered or multilayered conjugated structure.
[0061] FIG. 2 is a schematic side cross-sectional view of another
multilayer repulpable packaging composite material 40 according to
the present embodiments. The illustrated embodiment includes a
mineral-containing layer 22 substantially and continuously bonded
to the first surface 30 of a fiber-containing layer 32. In contrast
to the embodiment of FIG. 1, in the embodiment of FIG. 2 the second
surface 34 of the fiber-containing layer 32 is not bonded to a
mineral-containing layer 22.
[0062] FIG. 3 is a schematic side cross-sectional view of a
repulpable mineral containing material according to the present
embodiments. The illustrated embodiment includes a
mineral-containing layer 22 having both the first and second
surfaces 30, 34 uncovered by a mineral-containing layer 22.
[0063] FIG. 4 is a schematic detail view of a pellet 42 of a
mineral-containing resin with mineral particles interspersed within
a bonding agent, according to the present embodiments. Pellets such
as that illustrated in FIG. 4 may be used in an extrusion process
to adhere the mineral-containing layer 22 and the fiber-containing
layer 32 to one another. With reference to FIG. 4, the mineral
particles 26 are interspersed within the bonding agent 28 within
the pellet 42.
[0064] FIG. 5 is a schematic side cross-sectional view of another
multilayer repulpable packaging composite material according to the
present embodiments. The illustrated embodiment includes a first
mineral-containing layer 22 substantially and continuously bonded
to the first surface 30 of a fiber-containing layer 32. A second
mineral-containing layer 44 is substantially and continuously
bonded to the second surface 34 of the fiber-containing layer 32.
The second mineral-containing layer 44 comprises three layers or
plies of the first mineral containing layer 22. The first and
second mineral-containing layers 22, 44 may be secured to the
fiber-containing layer 32 through any of the processes described
herein, such as coextrusion, extrusion-lamination, etc., or through
any other process. The plies 22 of the second mineral containing
layer 44 may be secured to one another through any of the processes
described herein, such as coextrusion, extrusion-lamination, etc.,
or through any other process. One or more of the plies 22 may
comprise a mineral content and/or a bonding agent that is different
from the mineral content and/or the bonding agent of another one or
more of the plies 22. Further, the illustrated embodiment in which
the second mineral-containing layer 44 comprises three layers or
plies 22 is only one example. In other embodiments the second
mineral-containing layer 44 may have any number of layers or plies
22, such as two layers or plies, four layers or plies, five layers
or plies, etc. In yet further embodiments, the fiber-containing
layer 32 may have a multilayer mineral-containing layer 44 adhered
to both the first and second surfaces 30, 32.
[0065] FIG. 6 is a schematic side cross-sectional view of another
multilayer repulpable packaging composite material 46 according to
the present embodiments. The material 46 of FIG. 6 includes
multiple layers of any of the material layers described herein,
such as a first dual layer 48 and a second dual layer 50 with a
corrugated layer 52 there between.
[0066] The composite materials illustrated in the foregoing figures
and described above are well-suited for use as packaging materials,
such as for packages for containing one or more products. For
example, and without limitation, such packages may comprise folding
cartons and/or boxes. The package material has high performance
heat seal characteristics, elevated barrier performance, is
repulpable, and provides excellent cosmetics and favorable
economics. The present composite materials can also be used as
components, or layers, of multilayer packaging structures, such as
corrugated boxes, and/or be used as a single-layer or multilayer
corrugated liner or medium.
EXAMPLE 1
[0067] To form a repulpable composite, a 38.5% by weight
mineralized HPDE-PE resin containing additives was compounded using
wet ground and coated for dispersion finely ground within a range
of about approximately 5-14 micron mean particle sized
limestone-originating CaCO.sub.3 particles with incremental
crystalline silica content within a range of from about 0.2% to
about 3.5%. The specific heat of the ground CaCO.sub.3 particles
was from about 0.19 to about 0.31 kcal/kg.degree. C. The HDPE had a
density within a range of about 0.939 to about 0.957 g/cm.sup.3 and
the PE had a density of from about 0.916 g/cm.sup.3 to about 0.932
g/cm3. The HDPE-PE bonding agent had a melt flow index of 14 g/10
minutes. The finished and pelletized mineralized compound had an
approximate density within a range of about of 0.125 to about 1.41
g/cm.sup.3. The compound was coextruded using the mineralized
HDPE-PE composite layer as a base layer applied at 22 g/m.sup.2
coating thickness contacting the uncoated side of 320 g/m2 weight
Klabin virgin paper surface having a TAPI T-441 Sheffield
Smoothness of 74, a 7.5% moisture content, and a TAPPI T 556 MD-CD
Taber Stiffness of 39.9 and 17.4, respectively. The minor layer, or
top facing, outer, polymer bonding agent mineral-containing layer
of the coextrusion was about 8 g/m.sup.2 weight having a mineral
content from about 4% to about 65%, the base layer being
predominately crystalline using the top layer to provide additional
moisture barrier at box bend, scoring, and folding joints. The
extrusion processing condition melt temperature for the base layer
was within a range of approximately 560.degree. F. to 610.degree.
F. with barrel temperatures from zone one to zone six from about
405.degree. F. to 600.degree. F. Base layer die temperature zones
were approximately 575.degree. F. to 600.degree. F. The extruder
die gap setting was within the range of 0.025''-0.046''. Unfilled
Westlake.RTM. brand top neat PE mineral-containing layer processing
was consistent with neat LDPE. The extruder air gap was
approximately 4''-10'', providing sufficient base layer oxidation
and excellent adhesion use gas pre-heat, but without ozone or
primer layers. The extrusion line speeds were within the range of
150-600 meters per minute across a fiber web with within 50''-118''
range. Post corona treatment was used. Roll stock was in-process
quality control checked for adhesion using "tape" testing and
saturated for pin holing. Coat weight testing was done consistently
using lab instrumentation. Finished and coated roll stock was
rewound and sent for converting. Successful converting and
packaging article forming, e.g. folding cartons/boxes, were done up
to eight months post-extrusion coating. Using room temperature
adhesives during converting, the roll stock was run on high speed
detergent box production lines at speeds from about 100 to 500
cartons per minute. The enclosed detergent, being sensitive to
moisture exposure, was shipped in tropical moisture conditions.
Glue seams and small, medium, and large carton sizes were
successfully formed having sufficient fiber tear, meeting standards
with both room temperature and hot melt adhesives, including the
manufacturer's seam. Moisture barrier testing was completed for
large size sampling sizes, which included full converted and formed
case samples having MVTR performance of 13.91 g/m2/24 hours with a
minimum of 13.03 g/m.sup.2/24 hours, with a standard deviation of
0.86. These results compared to 40 g/m.sup.2 inline primed and then
applied aqueous PVDC coatings on the same Klabin board having an
average MVTR of 18.92 g/m.sup.2/24 hrs with a minimum of 16.83
g/m.sup.2/24 hours, a maximum of 20.89 g/m.sup.2/24 hrs, with a
standard deviation of 2.00, and also compared to 20 micron thick
BOPP primed and roll-to-roll laminated on the same Klabin board
having an average MVTR of 15.03 g/m.sup.2/24 hrs with a minimum of
13.20 g/m.sup.2/24 hrs, a maximum of 16.6 g/m.sup.2/24 hrs, with a
standard deviation of 1.41.
EXAMPLE 2
[0068] To form a repulpable and recyclable composite, a 43.5% by
weight mineralized PE resin containing additives was compounded
using wet ground and coated with fatty acid containing materials
for dispersion and finely ground approximately 4-12 micron mean
particle sized limestone-originating CaCO.sub.3 particles with
incremental crystalline silica content of less than from about 0.2%
to about 5%. The resin blend also had 5% by weight titanium dioxide
(TiO.sub.2) for a total mineral content of from about 48.5% by
weight. The specific heat of the ground CaCO.sub.3 particles was
0.21 kcal/kg.degree. C. The PE had a density of 0.919 g/cm.sup.3 to
about 93.1 g/cm.sup.3. The PE bonding agent had a melt flow index
of 16 g/10 minutes. The finished and pelletized mineralized
compound had an approximate density of 1.38 g/cm.sup.3. The
compound was then extruded using the mineralized PE and TiO.sub.2
composite layer as a mono layer applied at 32 lbs/3 msf coating
weight contacting the uncoated side of Rock Tenn AngelCote.RTM.
approximately 100% recycled fiberboard with a nominal basis weight
of 78 lbs/msf, with the paper surface having a TAPPI T-441
Sheffield Smoothness of approximately 68-72, a 5% to 7.5% moisture
content, and a TAPPI T 556 MD-CD Taber Stiffness g-cm of 320 and
105, respectively. The extrusion processing condition melt
temperature was approximately 585.degree. F. with barrel
temperatures from zone one to zone six from about 400.degree. F. to
about 585.degree. F. Die temperature zones were approximately
575.degree. F. to 585.degree. F. The extruder die gap setting was
within the range of 0.025''-0.030''. The extruder air gap was
approximately 6''-10'', providing excellent extrudate to fiber
adhesion without a gas pre-heat, ozone, or primer layers. Extrusion
line speeds were within the range of 150-1400 feet per minute
across a 80''-118'' web width. Post corona treatment was used. Roll
stock was in-process quality control checked for adhesion using
"tape" testing and saturated for visual pin holing. Post production
coat weight testing was done consistently using lab
instrumentation. Finished and coated roll stock was rewound and
sent for converting. Successful converting and packaging forming
was done up to three months postextrusion coating. During
converting, the roll stock was run for use in high barrier MVR
requirement frozen seafood box production lines at speeds up to 250
boxes per minute. The finished composite material was formed, bent,
scored, and machined at standard production rates. The
mineral-containing surface layer was efficiently offset printed
using standard industry inks and aqueous press coatings. The
mineral coating layer was highly opaque and improved the brightness
of the base paper surface from about 59 bright to about 76 bright.
The mineral layer had a resident dyne level range of 44-48 as
measured during post-production testing. Moisture barrier testing
was completed for large size sampling sizes, which included full
convertedand formed case samples having MVTR performance of 12 to
16 g/m.sup.2/24 hrs@100% humidity in tropical conditions with
mineral composite layer coat weights from 12 lbs/3 msf to 16 lbs/3
msf.
EXAMPLE 3
[0069] Example 3 illustrates three different finished repulpable
composites containing bleached virgin board SBS paper within a
caliper range from about 0.014'' to about 0.028'' having a
mineral-containing layer extrusion-coated to the fiber-containing
layer. These composites were analyzed for ash content with Tappi
standard T2 1 1, and for repulpability using an in-house procedure
developed by the Georgia Institute of Technology. Results indicated
that ash content varied from about 2.21% up to about 21.44%. Screen
yield and overall recovery seem to depend at least in part on ash
content of the starting paper. A 40% by weight mineralized PE resin
and a 47% by weight mineralized PE resin, both containing
additives, were compounded using wet ground and coated for
dispersion finely ground approximately 5.0 to 13.0 micron mean
particle sized limestone-originating CaC03 particles with
incremental crystalline silica content of less that about 5% by
weight. The specific heat of the ground CaCO.sub.3 particles was
0.21 kcal/kg.degree. C. The PE had a density from about 0.919
g/cm.sup.3 to about 93.2 g/cm.sup.3. The PE bonding agent had a
melt flow index of 16 g/10 minutes. The finished and pelletized
mineralized compound had an approximate density from about 1.34
g/cm.sup.3 to about 1.41 g/cm.sup.3. The compound was then extruded
as a mono layer substantially and continuously applied on the
fiber-containing layer at from about 7.5 lbs/3 msf to about 16
lbs/3 msf layer weight contacting the uncoated side of
International Paper Fortress SBS and Clearwater Paper Candesce SBS
having approximately 89% to approximately 100% bleached virgin
fiberboard with nominal basis weight from about 182 lbs to about
233 lbs, with the paper surface having a TAPPI T-441 Sheffield
Smoothness of approximately 68-72, a 5% to 7.5% moisture content,
and a TAPPI T 556 MD-CD Taber Stiffness g-cm above 375 and 105,
respectively. The extrusion processing condition melt temperature
was from about 565.degree. F. to about 610.degree. F., with barrel
temperatures from zone one to zone six from about 400.degree. F. to
about 605.degree. F. The die temperature zones were approximately
575.degree. F. to 610.degree. F. The extruder die gap setting was
within the range of about 0.020''-0.040''. The extruder air gap was
approximately 4''-16'', providing excellent extrudate to fiber
adhesion without a gas pre-heat, ozone, or primer layers. The
extrusion line speeds were within the range of 150-1600 feet per
minute across a 55''-118'' web width. Post corona treatment was
used. Roll stock was in-process quality control checked for
adhesion using "tape" testing and saturated for visual pin holing.
Post production coat weight testing was done consistently using lab
instrumentation. Finished and coated roll stock was rewound and
sent for converting. Successful converting and packaging forming
was done up to three months postextrusion coating. During
converting, the roll stock was run for use in high barrier MVR
requirement frozen seafood box production lines at speeds up to
250-500 boxes per minute, and cupstock as well as ice cream
packaging material converted from about 150 to about 600 formed
units per minute. The finished composite material was formed, bent,
scored, and machined at standard production rates. The
mineral-containing surface layer was efficiently offset printed
using standard industry inks and aqueous press coatings. The
mineral coating layer was highly opaque and maintained the fiber
layer brightness of the base paper surface from about 80 to about
90 bright. The mineral layer had a post corona treatment resident
dyne level range of 42-56 as measured during post-production
testing. Moisture barrier testing was completed for large size
sampling sizes, which included full converted and formed case
samples having MVTR performance of about 8 g/m.sup.2/24 hrs to
about 16 g/m.sup.2/24 hrs@100% humidity in tropical conditions with
mineral composite layer coat weights from about 7.5 lbs/3 ms to
about 16 lbs/3 msf. Packages were closed and sealed using standard
heat seal procedures found on cup forming and folding carton
production lines.
EXAMPLE 4--REPULPABILITY EXPERIMENT
1. Ash Content
[0070] Ash content was measured following Tappi standard T413. The
time at maximum temperature was extended to eight hours to ensure
complete ash.
TABLE-US-00012 TABLE 12 Ash/Solids Content for Six Paper Samples
Ash/Solids Content Sample Dish, g Sample Wt., g Solids % Ash
Content % 1# 27.7401 1.1446 95.83 21.41 Duplicate 15.8099 1.1136
96.20 21.46 Average 96.02 21.44 2# 18.8742 1.0837 96.16 5.41
Duplicate 16.1962 0.9697 96.11 6.45 Average 96.14 5.93 3# 15.7174
1.0131 95.92 2.17 Duplicate 16.5933 1.0285 95.73 2.26 Average 95.83
2.21 4# 17.9733 0.9974 96.09 9.31 Duplicate 18.4839 1.0778 95.75
9.32 Average 95.92 9.32 5# 16.3182 1.0548 95.92 4.11 Duplicate
18.3800 1.2260 96.28 3.83 Average 96.10 3.97 6# 28.1106 1.3772
94.88 2.80 Duplicate 27.5611 1.5707 95.24 2.76 Average 95.06
2.78
[0071] The above results indicate that the ash content of sample 1
# is 21.44%, the highest among the six samples, whereas that of
sample 3# is only 2.21%. It is contemplated that the values shown
in Table 12 above may vary by about .+-.50%.
2. Repulpability
[0072] Around 25 g of oven dried paper samples were tom into
1''.times.1'' pieces and weighted into a preheated (around
52.degree. C.) Waring blender, which was equipped with a special
blade to reduce fiber cutting. After 1,500 ml of hot (around
52.degree. C.) water was added, the paper was disintegrated on low
speed (15,000 rpm) for 4 minutes. The content was then transferred
quantitatively into a British disintegrator using 500 ml hot water
as rinsing liquor, so that the pulp slurry had a temperature around
52.degree. C. The pulp suspension was then de-flaked for 5 minutes
with a British disintegrator at 3,000 rpm. The disintegrated pulp
was screened by using a Valley flat screen with 0.01'' slot
openings for 20 minutes. During the screening, a water head over
the screen was maintained at 3'' and water flow was kept constant.
Accepts and rejects were collected and were used to calculate the
screen yield (accepts/starting paper*100) and overall recovery
((accepts+rejects)/starting paper*100). Images of the accepts and
rejects were taken to examine the fibers and flakes. After full
completion of the repulpability cycle, the entire procedure was
completed without using an acid wash to clean the flat screen
during the test or dismantling the pressure screens to clean them
before completing the test. Also, there was no visible deposition
on any part or the disintegrator during the test.
TABLE-US-00013 TABLE 13 Repulpability Data of the Paper Samples
Start Screen Overall Sample Pulp, g Accepts, g Rejects, g Yield, %
Recovery, % #2 26.448 20.511 1.754 77.55 84.18 #3 25.203 19.421
1.963 77.06 84.85 #4 26.235 20.700 2.044 78.90 86.69
[0073] The samples were disintegrated for 70,000 revolutions. It is
contemplated that the values shown in Table 13 above may vary by
about .+-.50%.
3. Determination of Fibers, Plastics, and Ash
Compositions--Determined Ash Content of the Fraction Following the
Procedure Stated in 1 (Above)
[0074] Around 0.2 g was weighted into a 50 plastic vial. After 1.8
ml of 72% sulfuric acid was added, the content was mixed thoroughly
and the sample mass turned to a paste. The vial was then set in a
30.degree. Cheating block for 1 hour, and the content was stirred
periodically. By the end of the heating treatment, water was added
to the vial until a total of 50 ml volume was reached. The vial was
capped and set in a 121.degree. C. autoclave for two hours. This
would completely hydrolyze the carbohydrate components and
solubilize the acid soluble inorganics. By the end of hydrolysis,
the acid insoluble substances were collected over a tarred glass
filter, which was preheated at 550.degree. C. overnight. The
collected substances were plastics plus acid insoluble inorganics
(ash), which was determined by the procedure stated under heading 1
above. Thus, the fiber content was calculated from the weight
difference of starting materials and substances after hydrolysis
minus the acid soluble inorganics. This portion of inorganics was
determined from the ash content stated under heading 3 above, minus
acid insoluble inorganics. The plastics were the weight difference
of acid insoluble substances minus acid insoluble inorganics.
[0075] Validation--In validation run, 1.5 g starting materials was
first hydrolyzed with 15 ml of 72% sulfuric acid at room
temperature for 1 hour followed by a 3% sulfuric acid hydrolysis
for 4 hours at boiling temperature.
4. Stickies Analysis
[0076] Around 0.3 g materials were hydrolyzed following the
procedure stated under heading 3 above. The hydrolyzed content was
filtered through black filtering paper (15 cm diameter). The
retained white residues were thoroughly washed with water until
neutral. When the filter paper was dry, the residues on the black
filtering paper were scanned with a HP scanner. A known dimension
shape was placed in the scanner as a reference. The image thus
acquired was input to Image-J software. Set threshold at 125/255
and scale based on the insert reference. The particles were
analyzed and the output was input into MS Excel for further
calculations. The stickies content was expressed as specified
stickies area, which was defined as total stickies area in
mm.sup.2/weight of starting materials in g.
5. Fate of Rosin Acids
[0077] Proper amount of mass from each fraction was weighted into
15 ml vials. After 10 ml DCM and 3 drops of 2 M HCl were added, the
vial was firmly capped with Teflon-lined caps, and shaken for 3
minutes. The vial was set in room temperature overnight. 1 ml
extract was filtered through a layer of sodium sulfate, and 100
.mu.l clear filtrate was measured into a 1 ml GC vial. After the
content was dried under a stream of nitrogen, the residues were
derivatized with MSTFA (N-Methyl-N-(trimethylsilyl)
trifluoroacetamide) at 50.degree. C. for 30 minutes with periodic
shaking. 1 .mu.l derivatized mixture was injected into the GC/MS
for analysis. The GC was equipped with 60 meter SPB DB-5 fused
silica capillary column and helium was used as carrying gas. GC
operation conditions were set as follows: initial temperature
120.degree. C., initial time 5 min., rate 15.degree. C./min., final
temperature 315.degree. C., and final time 30 minutes, inject port
temperature 250.degree. C. The components were analyzed using an HP
5975C mass detector in EI mode. The operation parameters were
properly set to realize maximum detection limit. Identification of
individual compounds based on the commercial mass spectra libraries
and inhouse libraries. Peak area was used to anticipate the total
mass of rosin acids.
6. Starch Detection
[0078] Around 0.2 g materials were weighted into a 10 ml vial.
After 5 ml water was added, the vial was capped and placed in a
105.degree. C. oven overnight. Around 2 ml water extract was
transferred to a test tube and added with 2 drops of 0.1 M iodine
solution. If the solution inside the test tube turned to blue, it
indicated that starch was present.
Results
1. Repulpability
[0079] Coated paper board and product are repulped and recovered in
three fractions: accepts, rejects, and wash-out. The oven dry
weight of each fraction, along with the accepts yield and overall
yield, are listed in Table 14, below.
TABLE-US-00014 TABLE 14 Repulpability Data of the Paper Samples
Repulpability Start Wash- Accepts Overall pulp, Accepts, Rejects,
out, Yield, Yield, g g g g % % CS-1 26.616 22.388 2.255 1.711 84.12
99.01 IP Mix 26.170 20.573 1.376 3.770 78.61 98.28 CLWR 2 25.257
20.123 1.056 3.930 79.67 99.42 CLWR 8.1 25.550 20.572 0.919 3.941
80.51 99.53
[0080] Results indicated that the accepts yield for all studied
samples is close to 80%.
[0081] Sample CS-I had the highest accepts yield and the least
amount of wash-out. This result may be due to the uncoating feature
of the based paper sheet. For all the samples, the overall yield
almost reaches 100%, indicating excellent recovery of the starting
materials in the three fractions. All the accepts had particles of
impurities in various sizes. Accepts of some samples also contain
fragments of plastics that may have been broken down from the
plastic coating. Judged from the reference ruler, the size of those
particles is less than 1 mm. The rejects also contain small
quantities of fibers. During the entire procedure, was completed
without the use of acid wash to clean the flat screens in the
repulpability tests or dismantling the pressure screens to clean
them before finishing the recyclability test. Further, there was no
visible deposition on any part of the disintegrator during the
repulpability test or anticipated in a recyclability test. It is
contemplated that the values shown in Table 14 above may vary by
about .+-.50%.
2. Compositions of the Three Fractions
[0082] Compositions of the fractions are divided into three
categories: fibers, plastics and inorganics which may come from the
fillers in the base paper and the mineral coatings in the coating
layers. Through the acid hydrolysis-ash operations, the fibers,
plastics and inorganics can be distinguished and quantified. This
is based on the fact that fibers are composed of carbohydrates and
they are readily hydrolyzed in sulfuric acid solution under
elevated temperature. Plastics, however, are generally resistant
toward such hydrolysis and will be recovered as insoluble
substances. In the ashing process, both fibers and plastics will be
burnt out. Inorganics survive this process and are recovered as
ash.
[0083] Table 15, below, lists the experimental results indicating
the percentage of each fraction in each sample.
TABLE-US-00015 TABLE 15 Percent Compositions of the Three Fractions
Accepts Rejects Wash-out Sample Ash Fibers Plastics Ash Fibers
Plastics Ash Fibers Plastics Ash CS-I 0.24 98.92 0.74 0.40 3.56
96.44 0.04 82.44 1.47 17.78 IP Mix 8.18 92.18 3.21 4.75 1.05 89.28
9.22 68.43 2.56 29.01 CLWR_2 10.33 94.43 1.04 4.53 5.05 57.43 37.52
63.07 2.21 34.72 (94.17) (1.30) CLWR_8.1 8.43 94.42 1.00 4.58 10.59
54.87 34.54 61.82 2.79 35.39 (94.11) (1.31)
[0084] Note: Data in parentheses are validation runs. Plastics
columns can represent either mineralized layer fragments or
separated plastic materials or both. It is contemplated that the
values shown in Table 15 above may vary by about .+-.50%.
[0085] In order to obtain reliable results, analysis to accepts of
sample CLWR-2 and CL WR-8 was performed in triplet runs: a
duplicate run to produce the average result, and a third run in
large sample size to serve as validation. As indicated, the
majority of the accepts is fibers, accounting for over 92% of the
mass. Ash and plastics are minor components existing probably in
the forms of small particles. Comparing to sample CS-I, all the
accepts from other three samples contains higher amounts of
inorganics. As to the plastics components, IP Mix has substantial
high quantity than CS-I, whereas those among CS-I, CLWR-2 and
CLWR-8.1 are comparable. Plastics are the dominant components in
the rejects fraction, especially in sample CS-1. Sample IP Mix, CL
WR-2 and CL WR-8.1 have increasingly amounts ofinorganics in the
rejects. It is not known if these inorganics are closely packed
inside the plastics or presented as separated particles. In the
washout, the fibers are the major components, especially in sample
CS-I and IP MIX. Sample CL WR-2 and CL WR-8.1 have increasingly
amounts of inorganics, probably presented as colloid particles in
the washing liquor.
3. Stickies Analysis
[0086] Impurities in the accepts are the major concern m the
recycled pulp fibers. Although composition analysis in section 2
provides information regarding these impurities, a visualized
analysis can provide more subtle features of the impurities.
Stickies analysis (some of the particles could also be referred to
as "dirties") is thus performed to reveal the particle content and
their size distribution.
TABLE-US-00016 TABLE 16 Stickies Analysis Results CLWR-2 CLWR-8.1
Fibers Rejects Washout Fibers Rejects Washout Stickies, 108 n/a n/a
123 n/a n/a mm.sup.2/g Rosin +++ + +++ +++ + +++ Starch + Not + +
Not + detected detected
[0087] Table 16 stickie count is represented as a number of
stickies contained in the accepts sampling prior to any further
processing. Therefore, the 3 gram hand sheets subsequently made
from the accepts fibers contained I 00% of the stickies and other
miscellaneous particles in the accepts immediately after pulping
but before further cleansing or processing such as cleaning,
flotation, etc. The hand sheets are pressed and dried at
350.degree. F. and 500 psi on a Carver press for 5 minutes and
tested for performance consistent with TAPPI T 537, TAPPI T277,
TAPPI T 220, TAPPI 815, TAPPI T 826, TAPPI T 403, TAPPI T 831 and
TAPPI T563. It is contemplated that the values shown in Table 16
above may vary by about .+-.50%.
[0088] Result shown in FIG. 7 indicate that contents of stickies in
both CLWR-2 and CLWR-8.1 are comparable. Particle size distribution
plots indicate that all the stickies have a size less than 0.4 mm.
All particles having an area less than 0.05 mm.sup.2 are dominant,
with approximately 80% or more of the particles 0.0015 mm.sup.2 or
less. This result, however, is highly in line with what have been
observed the accepts for each sampling. Since no further processing
e.g. cleaning, reverse cleaning, flotation, high density cleaning,
sidewall washing, peroxide dispersion, sodium hydrosulfite
bleaching, hydrosieve washing, or post flotation at specified pH
levels, etc., of the accepts occurred, 100% of the stickies or
diliies residing in the unprocessed accepts passed directly through
to the handsheets. Upon completion of the handsheets, no
substantial or important visual or cosmetic difference from that of
the virgin control board samples were seen. This exceptional
cosmetic result is primarily a factor driven by the very small
overall particle size and the white, opaque, color which closely
matches the bleached board SBS fibers found in the handsheets and
control samples. Further, 100% of the particles are less than or
equal to 0.4 mm.sup.2 and therefore would not be considered large
enough for cosmetic considerations. It is expected that the
mineralized board testing samples CS-I, IP MIX, CL WR 8.1 CL W 2
and the handsheets would be considered fully recyclable fibers
based on structural, cosmetic, and other considerations including
processability within about pH 6 to 8.+-.0.5 pH levels, fiber
processing temperature levels from about 110.degree. F. to about
135.degree. F., pulper consistency from about 1.2 to 30%, pulping
time from about 10 minutes to about 40 minutes, fiber on fiber
yield from about 60% to about 95% and hand sheet drying
temperatures in the range of about 240.degree. F. to about
290.degree. F., with finished sheet moisture levels from about 5%
to 9%, recyclability testing methods in accordance with testing
standards established by TAPPi T220, T8 1 5, T826, T403, T831,
T537, T277, T563.
4. Fate of Rosin Acids
[0089] Rosin is a collective name given to a group of chemicals
including abietic acid, pimaric acid, isopimirc acid, palustric
acid, dehydroabietic acid, etc. The rosin used in the paper making
process can also be oxidized into different forms. Nonetheless, the
acids are readily extracted by using DCM in acidic medium, and can
be easily separated by using a neutral GC capillary column.
[0090] Results of GC/MS analysis to the three fractions from sample
CL WR-2 and CL WR-8.1 are shown in FIG. 7. FIG. 8 illustrates a
typical total ion spectrum of the DCM extract.
[0091] As indicated, the rosin acids are separated completely by
GC. Judged from the peak area, the fibers fraction contains the
highest amount of rosin, following by the washout and the rejects.
It is contemplated that the values shown in FIG. 8 may vary by
about .+-.50%.
5. The Whereabouts of Starch
[0092] Starch's whereabouts among the three fractions is determined
by iodine detection. It is well known that starch will tum the
iodine-contained solution into blue color. Based on this
phenomenon, starch is found in both the fibers fraction and washout
fraction, but not in the rejects fraction, as indicated in Table
3.
EXAMPLE 5
[0093] By weight 40% to 60% mineralized resins were applied via
extrusion coating were to uncoated and clay coated virgin bleached
boards with weights from about 57 lbs per thousand square feet
(msl) to about 77 msf and were repulped to produce three fractions:
the accepts, the rejects and the wash-out. A full study including
repulpability, compositions of different fractions, stickies
analysis, fate of rosin acids and starch were performed. Results
indicated that the accept yield was over 78%, and an overall
recovery of almost I 00% was reached when the accepts, the rejects
and the wash-out were compiled. In general, the accepts were
dominated with fibers, which accounted for over 92% of the mass.
However, small amounts of plastics and inorganics (fillers and
coatings) were also present. The rejects were mainly plastics, but
significant amount of inorganics were also found in some samples.
The wash-out collected from the washing liquor contained
significant amounts of fibers and inorganics with small portion of
plastics. Stickies content in the accepts without any cleaning,
screening, washing, or flotation was determined in mm.sup.2/g and
was 108 and 123 respectively for sample CWR-2 and CWR-8.1. The
stickies or non-fiber particles were quite unique in composition
and do not fit the standard industry definition as such, for
example, they were not comprised of adhesives, hot melts, waxes, or
inks. They were instead comprised of small dense fragmented mineral
particles with varying amounts of PE bonding agent attached,
forming primarily structures appearing to be easily dispersed as
individual particles within the accepted fibers. Other
characteristics included relatively high surface energy and little,
if any, tackiness. They appeared to resist deformability and
appeared to have little potential to cause problems with
deposition, quality of sheet, and process efficiency. The stickies
and other various particles were predominantly opaque and white in
color, with densities projected to fall within a range from about
1.10 g/cm.sup.3 to about 4.71 g/cm.sup.3. Because of the nature of
the stickies, higher processing pH levels or peroxide bleaching
would not have the effect of increasing tackiness. The majority of
the stickies can be defined as "micro-stickies" as they pmlicles
sizes fell beneath 150 microns in size and above 0.001 micron in
size. Because of the benign nature of the stickie composition, it
is expected they will have little tendency to stick or adhere to
equipment during processing. The data indicated that the rosin
acids were found in almost all three fractions, but most of them
associated with the accepts and the wash-out. An iodine detect
technique found that the starch was in the accepts and the
wash-out, and the rejects was practically starch-free.
[0094] The composite structures described herein are well suited to
be formed into containers of various types. For example, FIG. 11
illustrates a container comprising a box 60. The box 60 may have
many applications, such as, without limitation, retail and
shipping. The box 60 may be in the form of a cube or other
parallelepiped that is sized to contain an item for retail sale
and/or shipping. The box 60 may be formed by preparing the
composite structure in the form of a pliable sheet, for example by
performing a milling step and/or other processing steps as
described above, cutting the structure into a desired shape, and
then folding and/or creasing the sheet, either manually or by
machine, such as via an automated cartoning process, to form the
final three-dimensional box shape. Abutting surfaces of the box 60
may be secured to one another using the various heat seal processes
described herein and/or other heat seal processes known in the art.
In the embodiment shown in FIG. 11, the composite structure forms
the walls of the box 60, including a bottom wall 62, one or more
side walls 64, as well as a foldover lid portion 66.
[0095] In other embodiments, the composite structures described
herein may be formed into a container liner 70 for retail and/or
shipping use, as shown in FIG. 12. The liner 70 may be used to line
a shipping or retail container 72 to cushion and/or protect a
product held in the container 72, as well as to provide moisture
resistance and deter infiltration of rodents and other pests. The
liner 70 fornled of the composite structure may be sufficiently
flexible and pliable such that it is capable of at least partially
conforming to the shape of the container 72.
[0096] In other embodiments, the composite structures described
herein may be formed into a shipping mailer 80, such as an
envelope, which may be used to ship documents and/or other items,
as shown in FIG. 11. The composite structure may be used to form a
part of or even all of the mailer structure 80, and may be
fabricated by using a series of folding, creasing, and/or
adhesive/heat seal steps to prepare the desired mailer shape.
[0097] In other embodiments, the composite structures described
herein may be formed into a display tray 90 and/or other sales
displays, as shown in FIG. 12. For example, the composite structure
may be cut, shaped, and/or folded into the shape of a display tray
90 capable of holding and displaying products for retail sale. The
composite structure can be molded by bending and/or folding, as
well as via thermo- and/or vacuum-forming to form desired parts of
the display 90.
[0098] Other non-limiting examples of applications for which the
present embodiments are well suited are described in one or more of
the following publications, each of which is incorporated herein by
reference in its entirety: U.S. Patent Application Publication Nos.
2009/0047499, 2009/0047511, and 2009/0142528.
[0099] The above description presents various embodiments of the
present invention, and the manner and process of making and using
them, in such full, clear, concise, and exact terms as to enable
any person skilled in the art to which it pertains to make and use
this invention. This invention is, however, susceptible to
modifications and alternate constructions from that discussed above
that are fully equivalent. Consequently, this invention is not
limited to the particular embodiments disclosed. On the contrary,
this invention covers all modifications and alternate constructions
coming within the spirit and scope ofthe invention as generally
expressed by the following claims, which particularly point out and
distinctly claim the subject matter of the invention.
* * * * *