U.S. patent application number 14/211132 was filed with the patent office on 2014-09-18 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 | 20140272352 14/211132 |
Document ID | / |
Family ID | 51528244 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140272352 |
Kind Code |
A1 |
Tilton; Christopher R. |
September 18, 2014 |
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: |
51528244 |
Appl. No.: |
14/211132 |
Filed: |
March 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61879888 |
Sep 19, 2013 |
|
|
|
61782291 |
Mar 14, 2013 |
|
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Current U.S.
Class: |
428/215 ;
428/330; 428/331; 428/335 |
Current CPC
Class: |
B32B 2260/046 20130101;
C08K 3/26 20130101; Y10T 428/259 20150115; C08J 5/045 20130101;
Y10T 428/258 20150115; B05D 1/265 20130101; B32B 19/02 20130101;
B05D 2252/00 20130101; B32B 27/12 20130101; C08J 2323/06 20130101;
B32B 27/20 20130101; B27N 3/28 20130101; B27N 3/04 20130101; D21J
1/08 20130101; B32B 2307/702 20130101; C08K 2003/265 20130101; Y10T
428/24967 20150115; B32B 2264/10 20130101; C08J 11/06 20130101;
D21F 11/12 20130101; Y10T 428/264 20150115; B32B 2307/72 20130101;
B32B 27/10 20130101; B32B 2260/025 20130101; D21H 5/12 20130101;
B32B 2439/00 20130101; B32B 2307/7246 20130101 |
Class at
Publication: |
428/215 ;
428/335; 428/331; 428/330 |
International
Class: |
D21J 1/08 20060101
D21J001/08; D21H 15/00 20060101 D21H015/00 |
Claims
1. A recyclable composite packaging structure, comprising: a
fiber-containing layer; and a barrier layer bonded to the
fiber-containing layer, the barrier layer including mineral
particles evenly dispersed in a matrix of a polyolefin bonding
agent; wherein the barrier layer has 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 a caliper from about 0.30
mil to about 3 mil.
2. The recyclable composite packaging structure of claim 1, wherein
the barrier layer is extruded.
3. The recyclable composite packaging structure of claim 1, wherein
the fiber-containing layer has a caliper from about 0.010'' to
about 0.030'' and a basis weight from about 136 lbs/3 msf to about
286 lbs/3 msf.
4. The recyclable composite packaging structure of claim 1, wherein
the barrier layer has a polyolefin content from about 30% to about
70% by weight.
5. The recyclable composite packaging structure of claim 1,
comprising about 1% to about 40% inorganic matter.
6. The recyclable composite packaging structure of claim 1,
comprising a total repulping recovery up to 98%.
7. The recyclable composite packaging structure of claim 1, wherein
the mineral particles comprise diatomaceous earth with ultrafine
nanoparticles having densities from about 2.4 g/cm.sup.3 to about
4.9 g/cm.sup.3 and particle sizes from about 100 nm to about 10
.mu.m.
8. The recyclable composite packaging structure of claim 1, wherein
the polyolefin bonding agent has molecular weights from about Mw
10,000 to about Mw 100,000 and a branching index (g') from about
0.99 to about 0.65 as measured at the Z-average molecular weight
(Mz) of the polymer.
9. The recyclable composite packaging structure of claim 1, wherein
the polyolefin bonding agent has an isotactic run length from about
1 to about 40.
10. The recyclable composite packaging structure of claim 1,
wherein the polyolefin bonding agent has a shear rate from about 1
to about 10,000 at temperatures from about 180.degree. C. to about
410.degree. C.
11. The recyclable composite packaging structure of claim 1,
wherein the mineral particles are cube or block particles.
12. The recyclable composite packaging structure of claim 1,
wherein the mineral particles have an average surface area from
about 1-1.3 m.sup.2/g to about 1.8-2.3 m.sup.2/g.
13. The recyclable composite packaging structure of claim 1,
wherein the mineral particles comprise calcium carbonate particles
having from about 18%-80% particle diameters finer than 6 .mu.m and
from about 33%-96% particle diameters less than 10 .mu.m and top
cut from about d98 of 4-15 .mu.m and a surface area from about 3.3
m.sup.2/g to about 10 m.sup.2/g, a surface treatment level from
about 0.6% to about 1.5% by weight of treatment agent or about 99%
by weight of the calcium carbonate.
14. The recyclable composite packaging structure of claim 1,
wherein the fiber-containing layer comprises nano-cellulose having
a crystalline content from about 40% to about 70%, including
nano-fibrils, micro-fibrils, and non-fibril bundles having lateral
dimensions from about 4 nm to about 30 nm and highly crystalline
nano-whiskers from about 100 nm to about 1,000 nm, with fiber
widths from about 3 nm to about 15 nm, having charge densities from
about 0.5 meq/g to about 1.5 meq/g, and the nano-cellulose having a
stiffness from about 140 GPa to about 220 GPa and a tensile
strength from about 400 MPa to about 600 MPa.
15. The recyclable composite packaging structure of claim 1,
wherein some of the mineral particles contain fatty acid and
stearate coatings having a Hunter reflectance (green) from about
91% to about 97%, a Hunter reflectance (blue) from about 89% to
about 96%, a Mohs hardness from about 2.75 to about 4.0, a particle
pH in water, 5% slurry, at 23.degree. C., from about 8.5 to about
10.5, a particle resistance in water, at 23.degree. C., from about
5,000 ohms to about 25,000 ohms, an ASTM D1199 maximum percentage
on a 325 mesh from about 0.05 to about 0.5, a volume resistivity at
20.degree. C. of 10.sup.9 to about 10.sup.11 ohms, a standard heat
of formation from its elements at 25.degree. C. from about 288.45
to about 288.49 kg-cal/mole, a standard free energy of formation
from its elements from about 269.53 to about 269.78 kg-cal/mole, a
specific heat 1 g 1.degree. C. (between 0.degree. C. and
100.degree. C.) from about 0.200 to about 0.214, a heat
conductivity of about 0.0071 g-ca/sec/cm.sup.2/1 cm thick at
20.degree. C., a coefficient of linear expansion
C=9.times.10.sup.-6 at 25.degree. C. to 100.degree. C. and
C=11.7.times.10 at 25.degree. C. to 100.degree. C.
16. The recyclable composite packaging structure of claim 1,
wherein the fiber-containing layer comprises vinyl and inorganic
mineral coatings and fillers.
17. The recyclable composite packaging structure of claim 1,
wherein the fiber-containing layer has a surface smoothness from
about 1.50 to about 3.15, a smoothness from about 150 to about 200
Bekk-seconds, an ash content from about 1% to about 40% by weight,
a static friction coefficient .mu..sub.s from about 0.02 to about
0.50, and a cellulose content having thermal conductivity from
about 0.034 to about 0.05 W/mk.
18. The recyclable composite packaging structure of claim 1,
wherein some virgin and recycled fiber types within the
fiber-containing layer include mechanical, thermo-mechanical,
chemo-thermo-mechanical, and chemical having an average aspect
ratio from about 5 to about 100, a softwood fiber thickness from
about 1.5 mm to about 30 mm, a hardwood fiber thickness from about
0.5 mm to about 30 mm, a filled fiber content from about 1% to
about 30%, a density from about 0.3 g/cm.sup.3 to about 0.7
g/cm.sup.3, fiber diameters from about 16 .mu.m to about 42 .mu.m,
a fiber coarseness from about 16 mg/100 m to about 42 mg/100 m, a
permeability from about 0.1.times.10.sup.15 m.sup.2 to about
110.times.10.sup.15 m.sup.2, a hydrogen ion concentration from
about 4.5 to about 10, a Tappi 496, 402 tear strength from about 56
to about 250, a Tappi 414 tear resistance from about m49 to about
m250, and a moisture content from about 2% to about 18% by
weight.
19. The recyclable composite packaging structure of claim 1,
wherein the fiber-containing layer comprises a combination of
recycled fiber, virgin fiber, thermo-mechanical pulp "TMP," virgin
kraft fiber, clay coated craft fiber, clay coated unbleached kraft
fiber, and solid bleached sulfate fiber.
20. The recyclable composite packaging structure of claim 1,
wherein the barrier layer comprises Tappi T410 weights from about
5.5 g/m.sup.2 to about 52.2 g/m.sup.2, Tappi T464 moisture barrier
values from about 0.46 g/100 in.sup.2 to about 37.7 g/100 in.sup.2,
Tappi T441 Cobb 2-minute water absorption from about 0.00 to about
0.40, T441 30-minute water absorption from about 0.00 to about
0.45, and a Tappi T559 grease resistance of 12.0.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application 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. The entire
contents of the priority applications are hereby incorporated by
reference herein and made a part of this disclosure.
TECHNICAL FIELD
[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
[0004] The present embodiments have several features, no single one
of which is solely responsible for their desirable attributes.
Without limiting the scope of the present embodiments as expressed
by the claims that follow, their more prominent features now will
be discussed briefly. After considering this discussion, and
particularly after reading the section entitled "Detailed
Description," one will understand how the features of the present
embodiments provide the advantages described herein.
[0005] Any or all of the below listed aspects may be a part of the
present embodiments:
[0006] Mineral particle densities within the polymer matrix of the
mineral-containing layer may be from about 2.4 g/cm.sup.3 to about
4.9 g/cm.sup.3.
[0007] Mineral particles within the polymer matrix of the
mineral-containing layer may comprise the cube and block class.
[0008] Calcium carbonate particles within the polymer matrix of the
mineral-containing layer may have about 18-80% particle diameters
finer than 6 .mu.m and about 33-96% particle diameters less than 10
.mu.m.
[0009] A hardness of mineral particles within the polymer matrix of
the mineral-containing layer may be from about 2.0 to 4.0 Mohs.
[0010] Mineral particles within the polymer matrix of the
mineral-containing layer may have 0.05 to 0.5 maximum % on 325 mesh
per ASTM D1199.
[0011] Mineral particles within the polymer matrix of the
mineral-containing layer may have a pH from about 8.5 to about
10.5.
[0012] The polymer bonding agent(s) within the mineral-containing
layer may have densities from about 0.908 g/cm.sup.3 to about 1.60
g/cm.sup.3.
[0013] The polymer bonding agent(s) within the mineral-containing
layer may have a physical melt flow index from about 4 g/m.sup.2/10
min to about 16 g/m.sup.2/10 min.
[0014] Minerals may be fully dispersed within the polymer bonding
agent matrix.
[0015] The polymer bonding agent(s) within the mineral-containing
layer may have a molecular weight (Mz) from about 150,000 to about
300,000.
[0016] The polymer content weight of the mineral-containing layer
may be from about 3.5 lbs/3 msf to about 50 lbs/3 msf.
[0017] The mineral-containing layer may have a modulus from about
1.8 GPa to about 4.5 GPa.
[0018] About 40-60% of the mineral-containing layer may have a
coefficient of thermal expansion from about 1.times.10.sup.-6 in/in
to about 8.times.10.sup.-6 in/in.
[0019] The mineral-containing layer may be applied to the
fiber-containing layer in coat weights from about 3 g/m.sup.2 to
about 20 g/m.sup.2.
[0020] Surfaces of the mineral-containing layer may have a
coefficient of static friction from about 0.18 to about 0.59.
[0021] The mineral-containing layer may include a mixture of
crystalline, semi-crystalline, and amorphous structures.
[0022] The polymer bonding agent(s) of the mineral-containing layer
may have crystallinity from about 60% to about 85%.
[0023] The mineral-containing layer may contain coupling agents
from about 0.05% to about 15% by weight.
[0024] The mineral-containing layer may contain from about 0.5% to
about 10% plastomers and elastomers with densities from about 0.86
g/cm.sup.3 to about 0.89 g/cm.sup.3 per ASTM D 792.
[0025] The mineral-containing layer may have differential scanning
calorimetry (DSC) melting peaks from about 59.degree. C. to about
110.degree. C.
[0026] The mineral-containing layer molecular weight ranges (Mw)
may be from about 10,000 to about 100,000.
[0027] About 10% to about 70% of the mineral-containing layer may
have a branching index (g') of about 0.99 or less as measured at
the Z-average molecular weight (Mz) of the bonding agent.
[0028] The polymer bonding agent(s) of the mineral-containing layer
may have an isotactic run length from about 1 to about 40.
[0029] The polymer bonding agent(s) of the mineral-containing layer
may have a physical shear rate from about 1 to about 10,000 at
temperatures from about 180.degree. C. to about 410.degree. C.
[0030] The mineral-containing layer may have a basis weight from
about 0.5 lbs/msf to about 175 lbs/msf.
[0031] The polymer bonding agent(s) of the mineral-containing layer
may have from about 20% to about 60% amorphous structure and from
about 20% to about 55% crystalline structure.
[0032] The polymer bonding agent(s) of the mineral-containing layer
may comprise polyethylene having an amorphous fraction from about
40% to about 85%.
[0033] The mineral-containing layer may have a copolymer
isotacticity index from about 20% to about 50% as measured by the
DSC method.
[0034] Mineral particles within the polymer matrix of the
mineral-containing layer may have an average surface area from
about 1.0-1.3 m.sup.2/g to about 1.8-2.3 m.sup.2/g.
[0035] Mineral particles within the polymer matrix of the
mineral-containing layer may have a Green Hunter reflectance range
from about 91% to about 97%, and a Blue Hunter reflectance range
from about 89% to about 96%.
[0036] The fiber-containing layer may contain inorganic mineral
coatings and fillers, including without limitation, kaolin clay,
mica, silica, TiO.sub.2, and other pigments.
[0037] The fiber-containing layer may contain vinyl and polymeric
fillers.
[0038] A surface smoothness of the fiber-containing layer may be in
the range of about 150 to about 200 Bekk seconds.
[0039] The fiber-containing layer may have an ash content from
about 1% to about 40%.
[0040] The fiber-containing layer may have any or all the
characteristics presented in the following table:
TABLE-US-00001 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/cm.sup.2 Fiber
Diameter 16-42 microns Fiber Coarseness 16-42 mg/100 m Fiber Pulp
Types Mechanical, Thermo-Mechanical, (Single- to Triple-Layered)
Chemi-Thermo-Mechanical, and Chemical Permeability 0.1-110 m.sup.2
.times. 10.sup.15 Hydrogen Ion Concentration 4.5-10 Tear Strength
(Tappi 496, 402) 56-250 Tear Resistance (Tappi 414) m49-250
Moisture Content 2%-18% by Weight
[0041] The fiber-containing layer may have any or all the
characteristics presented in the following table:
TABLE-US-00002 Burst Fiber Weight Tear Surface Strength (lbs/3 msf)
g/m.sup.2 Resistance (Mn) Roughness (kPa) 40-75 60-110 400-700
2.0-5.5 .mu.m 140-300 75 110-130 650-750 2.0-3.5 .mu.m 175-400 115
180-190 1400-1900 100-2500 mls/min 175-475 130 205-215 1600-2200
100-2500 mls/min 250-675 200 315-330 1900-3200 100-2500 mls/min
500-950 300 460-195 500-4000 100-2500 mls/min 700-1850
[0042] The mineral-containing layer may comprise a multilayer
coextrusion, such as up to six layers, with each layer having from
about 0% to about 70% by weight mineral content with a polymer
bonding agent.
[0043] A weight of the overall composite may be from about 2.5
lbs/3 msf to about 150 lbs/3 msf.
[0044] The polymer bonding agent(s) of the mineral-containing layer
may comprise linear, branched, and/or highly branched polymers.
[0045] The polymer bonding agent(s) of the mineral-containing layer
may comprise polyolefin(s) having a number average molecular weight
distributions (Mn) from about 5,500 to about 13,000, a weight
average molecular weight (Mz) from about 170,000 to about 490,000,
and/or a Z-average molecular weight (Mz) from about 170,000 to
about 450,000.
[0046] The mineral-containing layer may have a Mw/Mn ratio from
about 6.50 to about 9.50.
[0047] The mineral particles within the polymer matrix of the
mineral-containing layer may be surface treated at levels from
about 1.6 to about 3.5 mg surface agent/m.sup.2 of the
particle.
[0048] The mineral particles within the polymer matrix of the
mineral-containing layer may have a particle top cut from about d98
of 4-15 microns and a surface area from about 3.3 m.sup.2/g to
about 10 m.sup.2/g.
[0049] The mineral particles within the polymer matrix of the
mineral-containing layer may comprise CaCO.sub.3 coated with fatty
acids having from about 8 to about 24 carbon atoms, with a surface
treatment level from about 0.6% to about 1.5% by weight of the
treatment, or from about 90% to about 99% by weight of the
CaCO.sub.3.
[0050] The mineral-containing layer may be from about 0.5 mil thick
to about 5 mil thick.
[0051] Examples of non-fiber content in the fiber-containing layer
include, but are not limited to, about 50-95% of #1 clay or #1 fine
clay, about 3-20% by part calcined clay, about 3-40% by part
TiO.sub.2, about 2-45% vinyl acrylic, and from about 1% to about
35% protein binders, co-binders, or tri-binders.
[0052] The mineral-containing layer may contain incremental
quartz-silica content.
[0053] A process for recycling the present composite structure may
have reject rates from about 10% to about 25% by weight of the
starting composite, and screen plate efficiencies from about 60% to
about 100%, with screen plates having the option of using hole,
slotted, and contoured screens with one screen behind the other
with an A plate having the smallest perforations, an intermediary B
plate, and a C plate having the largest perforations, using
processes including high density, forward, and through flow
cleaners having a diameter from about 70 mm to about 400 mm and
particle process out of fibers having reject rates of about 0.1% to
about 30% and a particle removal efficiency from about 50% to 90%
by mass, and particle sizes from about 150 microns to 0.05
microns.
[0054] A process for recycling the present composite structure may
have feed-accept pressures in the range of about 2 kPa to about 12
kPa on smooth contoured and heavily contoured screens.
[0055] The present composite materials may have a pulper
consistency from about 3% to about 30%, pulping temperatures from
about 100.degree. F. to about 200.degree. F., pulping times from
about 10 min. to about 60 min., with pulping pH from about 6 to
about 9.5.+-.0.5, and screen holes from about 0.050'' to about
0.075'' and slots from about 0.006'' to about 0.020'', drum pulping
having an RPM from about 9 to about 20, having 4 mm to about 8 mm
holes, with hole-type screens with holes from about 0.8 mm to about
1.5 mm in size, 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 m/s to about 30 m/s.
[0056] Certain of the present embodiments comprise a recyclable
composite packaging structure. The structure comprises a
fiber-containing layer, and a barrier layer bonded to the
fiber-containing layer. The barrier layer includes mineral
particles evenly dispersed in a matrix of a polyolefin bonding
agent. The barrier layer has 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 a caliper from about 0.30 mil to about 3
mil. The barrier layer may be extruded. The fiber-containing layer
may have a caliper from about 0.010'' to about 0.030'' and a basis
weight from about 136 lbs/3 msf to about 286 lbs/3 msf. The barrier
layer may have a polyolefin content from about 30% to about 70% by
weight. The recyclable composite packaging structure may comprise
about 1% to about 40% inorganic matter. The recyclable composite
packaging structure may comprise a total repulping recovery up to
98%. The mineral particles may comprise diatomaceous earth with
ultrafine nanoparticles having densities from about 2.4 g/cm.sup.3
to about 4.9 g/cm.sup.3 and particle sizes from about 100 nm to
about 10 .mu.m. The polyolefin bonding agent may have molecular
weights from about Mw 10,000 to about Mw 100,000 and a branching
index (g') from about 0.99 to about 0.65 as measured at the
Z-average molecular weight (Mz) of the polymer. The polyolefin
bonding agent may have an isotactic run length from about 1 to
about 40. The polyolefin bonding agent may have a shear rate from
about 1 to about 10,000 at temperatures from about 180.degree. C.
to about 410.degree. C. The mineral particles may be cube or block
particles. The mineral particles may have an average surface area
from about 1-1.3 m.sup.2/g to about 1.8-2.3 m.sup.2/g. The mineral
particles may comprise calcium carbonate particles having from
about 18%-80% particle diameters finer than 6 .mu.m and from about
33%-96% particle diameters less than 10 .mu.m and top cut from
about d98 of 4-15 .mu.m and a surface area from about 3.3 m.sup.2/g
to about 10 m.sup.2/g, a surface treatment level from about 0.6% to
about 1.5% by weight of treatment agent or about 99% by weight of
the calcium carbonate. The fiber-containing layer may comprise
nano-cellulose having a crystalline content from about 40% to about
70%, including nano-fibrils, micro-fibrils, and non-fibril bundles
having lateral dimensions from about 4 nm to about 30 nm and highly
crystalline nano-whiskers from about 100 nm to about 1,000 nm, with
fiber widths from about 3 nm to about 15 nm, having charge
densities from about 0.5 meq/g to about 1.5 meq/g, and the
nano-cellulose having a stiffness from about 140 GPa to about 220
GPa and a tensile strength from about 400 MPa to about 600 MPa.
Some of the mineral particles may contain fatty acid and stearate
coatings having a Hunter reflectance (green) from about 91% to
about 97%, a Hunter reflectance (blue) from about 89% to about 96%,
a Mohs hardness from about 2.75 to about 4.0, a particle pH in
water, 5% slurry, at 23.degree. C., from about 8.5 to about 10.5, a
particle resistance in water, at 23.degree. C., from about 5,000
ohms to about 25,000 ohms, an ASTM D1199 maximum percentage on a
325 mesh from about 0.05 to about 0.5, a volume resistivity at
20.degree. C. of 10.sup.9 to about 10.sup.11 ohms, a standard heat
of formation from its elements at 25.degree. C. from about 288.45
to about 288.49 kg-cal/mole, a standard free energy of formation
from its elements from about 269.53 to about 269.78 kg-cal/mole, a
specific heat 1 g 1.degree. C. (between 0.degree. C. and
100.degree. C.) from about 0.200 to about 0.214, a heat
conductivity of about 0.0071 g-ca/sec/cm.sup.2/1 cm thick at
20.degree. C., a coefficient of linear expansion
C=9.times.10.sup.-6 at 25.degree. C. to 100.degree. C. and
C=11.7.times.10 at 25.degree. C. to 100.degree. C. The
fiber-containing layer may comprise vinyl and inorganic mineral
coatings and fillers. The fiber-containing layer may have a surface
smoothness from about 1.50 to about 3.15, a smoothness from about
150 to about 200 Bekk-seconds, an ash content from about 1% to
about 40% by weight, a static friction coefficient .mu..sub.s from
about 0.02 to about 0.50, and a cellulose content having thermal
conductivity from about 0.034 to about 0.05 W/mk. Some virgin and
recycled fiber types within the fiber-containing layer may include
mechanical, thermo-mechanical, chemo-thermo-mechanical, and
chemical having an average aspect ratio from about 5 to about 100,
a softwood fiber thickness from about 1.5 mm to about 30 mm, a
hardwood fiber thickness from about 0.5 mm to about 30 mm, a filled
fiber content from about 1% to about 30%, a density from about 0.3
g/cm.sup.3 to about 0.7 g/cm.sup.3, fiber diameters from about 16
.mu.m to about 42 .mu.m, a fiber coarseness from about 16 mg/100 m
to about 42 mg/100 m, a permeability from about 0.1.times.10.sup.15
m.sup.2 to about 110.times.10.sup.15 m.sup.2, a hydrogen ion
concentration from about 4.5 to about 10, a Tappi 496, 402 tear
strength from about 56 to about 250, a Tappi 414 tear resistance
from about m49 to about m250, and a moisture content from about 2%
to about 18% by weight. The fiber-containing layer may comprise a
combination of recycled fiber, virgin fiber, thermo-mechanical pulp
"TMP," virgin kraft fiber, clay coated craft fiber, clay coated
unbleached kraft fiber, and solid bleached sulfate fiber. The
barrier layer may comprise Tappi T410 weights from about 5.5
g/m.sup.2 to about 52.2 g/m.sup.2, Tappi T464 moisture barrier
values from about 0.46 g/100 in.sup.2 to about 37.7 g/100 in.sup.2,
Tappi T441 Cobb 2-minute water absorption from about 0.00 to about
0.40, T441 30-minute water absorption from about 0.00 to about
0.45, and a Tappi T559 grease resistance of 12.0.
[0057] Certain of the present embodiments comprise a method of
making a recyclable composite packaging structure including a
fiber-containing layer and a mineral-containing layer. The method
comprises extrusion coating the mineral-containing layer onto the
fiber-containing layer using a mineral-containing resin having
mineral particles interspersed within a polyolefin bonding agent.
The extrusion process is carried out under the following
conditions: the resin having a melt flow index from about 4 g/10
min. to about 16 g/10 min.; a melt temperature from about
440.degree. F. to about 640.degree. F.; an extruder screw or tube
barrel pressure from about 1,200 psi to about 2,500 psi; an air gap
from about 4'' to about 16''; a die gap from about 0.020'' to about
0.050''; barrel and die zone temperatures from about 400.degree. F.
to about 640.degree. F.; an extrusion line speed from about 100 FPM
to about 3,500 FPM; and an extrusion lamination line speed from
about 100 FPM to about 3,500 FPM. The mineral-containing resin may
comprise between 20% and 70% mineral content by weight. The
mineral-containing resin may comprise pellets. The
mineral-containing layer may be applied to the fiber-containing
layer in coat weights from about 4 lbs/3 msf to about 30 lbs/3 msf.
The recyclable composite packaging structure may not contain
water-based dispersions, aqueous dispersions, aqueous coatings,
emulsions, emulsion-containing coatings, water-containing
dispersions, press-line applications, or off-line mixing processes.
The mineral-containing layer, weighing from about 15 g/m.sup.2 to
about 50 g/m.sup.2, may be coextruded in line on an extrusion
coating machine and bonded by extrusion to the fiber-containing
layer. The mineral-containing layer may have a density from about
1.22 g/cm.sup.3 to about 1.41 g/cm.sup.3. The mineral-containing
layer may be from about 25% to about 75% amorphous and have a water
vapor transmission rate (WVTR) under tropical conditions from about
5 gm/m.sup.2 per day to about 22 g/m.sup.2 per day.
BRIEF DESCRIPTION OF THE DRAWINGS
[0058] 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:
[0059] FIG. 1 is a schematic side cross-sectional view of a
multilayer repulpable packaging composite material according to the
present embodiments;
[0060] FIG. 1A is a detail view of the portion of FIG. 1 indicated
by the circle 1A-1A;
[0061] FIG. 2 is a schematic side cross-sectional view of another
multilayer repulpable packaging composite material according to the
present embodiments;
[0062] FIG. 3 is a schematic side cross-sectional view of a
repulpable mineral-containing material according to the present
embodiments;
[0063] 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;
[0064] FIG. 5 is a schematic side cross-sectional view of another
multilayer repulpable packaging composite material according to the
present embodiments; and
[0065] FIG. 6 is a schematic side cross-sectional view of another
multilayer repulpable packaging composite material according to the
present embodiments;
[0066] FIG. 7 is a graph showing the stickies content of Sample 6#
from Table 12;
[0067] FIG. 8 is a graph showing a total ion spectrum of DCM
extract from a washout fraction of sample CLWR-2;
[0068] FIG. 9 is a container formed from a composite material
according to the present embodiments;
[0069] FIG. 10 is a container liner formed from a composite
material according to the present embodiments;
[0070] FIG. 11 is an envelope formed from a composite material
according to the present embodiments; and
[0071] FIG. 12 is a display tray formed from a composite material
according to the present embodiments.
DETAILED DESCRIPTION
[0072] 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
post-consumer 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).
[0073] 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.
[0074] 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.
[0075] When forming packaging that contains food products and dry
goods, heat sealability 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.
[0076] 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.
[0077] 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.
[0078] 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/cm.sup.3 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
successfully to 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.
[0079] 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 sealability 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.
[0080] 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.
[0081] 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 and 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.
[0082] 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''.
[0083] 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.
[0084] 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''.
[0085] 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-00003 TABLE 1 Composite Repulpability Mineral Content
Thermoplastic Screen Total Caliper of Barrier Bonding Yield
Inorganic Overall (in.) lbs/3 msf Layer(s) Agent (Accepts) 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%-65% 30%-70% 60%-90% 1%-40%
70%-98% 0.026 268 30%-65% 30%-70% 60%-90% 1%-40% 70%-98% 0.028 276
30%-65% 30%-70% 60%-90% 1%-40% 70%-98% 0.030 286 30%-65% 30%-70%
60%-90% 1%-40% 70%-98% 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.
[0086] 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.
[0087] 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-00004 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
[0088] 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.
[0089] 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.
[0090] 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-00005 TABLE 3 Operating Parameters, Mineralized Composite
Resins, Monolayer, Coextrusion, and Multilayer Mineral-Containing
Composites, to Fiber-Containing Layers ROLL Extruder #2-#6 Maximum
ranges Comments (coextrusion) or Plus & Minus as a % below do
not Extruder #1 separate downstream of stated value or represent
Monolayer units stated value limitations RESIN Earth Coating Earth
Coating SUPPLIER Standridge Color Standridge Color GRADE NUMBER TBD
TBD MELT FLOW - Carrier EST: 16 g/10 min. EST: 16 g/10 min. 4 g
10/min to 16 g/10 min Interspersed Resin(s)/bonding agent and non-
interspersed COMPOUND DENSITY 1.25 g/cm.sup.3 1.25 g/cm.sup.3
1.01-4.90 g/cm.sup.3 Molecular weight from (Mz 150,00 to 300,000)
MINERAL CONTENT 40% 40% General mineral Interspersed content 15-60%
by and non- weight interspersed MELT TEMPERATURE 590.degree. F.
(307.degree. C.) TBD .+-.20% DESIRED BARREL PRESS 1600-2200 psi TBD
1200-2500 psi From 1 to 6 extruders Composite Melt Flow 2-12 g/10
min 2-12 g/10 min 2 g/10 min-14 g/10 min Interspersed and Non-
Interspersed Air Gap 8'' 4''-12'' 4''-16'' Die Gap 0.025''-0.030''
0.025''-0.040'' 0.020''-0.050'' From 1 to 6 Coextrusion Monolayer
and Coextrusion or separate downstream #2-#6 Co-layers TEMPERATURE
SETTINGS Maximum Maximum Initial Settings Adjustment Settings Die
Adjustment Barrel Zones Barrel Zones Zone Die Zone Melt Temperature
590.degree. F. Up to .+-.25% BARREL ZONE #1 405.degree. F. Up to
.+-.35% Die Zone 1 585.degree. F. .+-.25% BARREL ZONE #2
540.degree. F. Up to .+-.35% Die Zones 2-10 595.degree. F. .+-.25%
(as applicable to equipment) BARREL ZONE #3 575.degree. F. Up to
.+-.35% Die Zone 11 585.degree. F. .+-.35% (as applicable to
equipment) BARREL ZONE #4 590.degree. F. Up to .+-.35% BARREL ZONE
#5 590.degree. F. Up to .+-.35% Other barrel Zones, if 590.degree.
F. Up to .+-.35% Other die zones Up to .+-.35% applicable on
specific if applicable equipment
[0091] 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/cm.sup.3 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.
[0092] 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-00006 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.degree. C.
[0093] Further, homogeneous blends of solid olefin polymers with
varying densities and melt indexes can be mixed within the mineral
composite layer, either interspersed or non-interspersed 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 polytheylene; 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/1-olefin
copolymers, the 1-olefin being produced in situ;
propylene/butadiene copolymers, isobutylene/isoprene copolymers,
ethylene/vinylcyclohexene copolymers, ethylene vinyl acetate
copolymers, ethylene/alkyl methacrylate copolymers,
ethylene/acrylic acid copolymers or ethyelene/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 alph-methystyrene, aromatic
homopolymers and copolymers derived from vinylaromatic monomers,
including styrene, alpha-methylstyrene, all isomers of
vinyltoluene, in particular p-vinyletoluene, all isomers of
ethylstyrene, propylstyrene, vinylbiphenyl, vinylnaphthalene and
blends thereof, homopolymers and copolymers of may have any desired
three dimensional structure, including syndiotactic, isotatic,
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 styren/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; unstaturated 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 aminocarboxylicacides and corresponding lactams;
polyesters and polyesters derived from dicarboxylic acids and diols
and from hydroxycarboxylic acids or the corresponding 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 poly lactic acids and its copolymers, cellulose,
polyhdyroxy alcanoates, polycaprolactone, polybutylene succinate,
polymers and copolymers of N-vinylpyrroolidone such as
polyvinylpyrrrolidone, 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 FOSS
polypropylene, thermoplastic elastomers, thermoplastic vulcinates,
polyvinylchloride, polylactic acid, virgin and recycled polyesters,
cellulosics, polyamides, polycarbonate, polybutylene
tereaphthylate, polyester elastomers, thermoplastic polyurethane,
cyclic olefin copolymer; biodegradable polymers such as
Cereplast-Polylactic acid, Purac-Lactide PLA, Nec 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.
[0094] 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, amino, malice anhydride, vinyl and
methtacryl. 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 suphate-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, TiO2 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-1 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.
[0095] 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.
[0096] 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 10-50%, thus greatly strengthening fiber bonding
characteristics under normal equipment operating conditions.
[0097] 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 1 to about 40. Further, the polymer bonding agent of
the mineral-containing layer has a shear rate range of from about 1
to about 10,000 at temperatures from about 180.degree. C. to about
410.degree. C.
TABLE-US-00007 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 D1199 Max % on 325
Mesh 0.05-0.5 Volume Resistivity @ 20.degree. C. 10.sup.9-10.sup.11
ohms pH 8.5-10.5 Standard Heat of Formation, CaCO.sub.3
288.45-288.49 Kg-cal/mole from its Elements @ 25.degree. C.
Standard Free Energy of Formation, 269.53-269.78 Kg-cal/mole
CaCO.sub.3 from its Elements Specific Heat (between 0 to
100.degree. C.) 0.200-0.214 Heat Conductivity 0.0071 g ca/sec
cm.sup.2 1 cm thick @ 20.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.
[0098] 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. Nano-cellulose 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.
[0099] 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,
CaCO.sub.3, 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-00008 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/cm.sup.2 Fiber Diameter 16-42 microns Fiber
Coarseness 16-42 mg/100 m Fiber Pulp Types Mechanical,
Thermo-Mechanical, (Single- to Triple-Layered)
Chemi-Thermo-Mechanical, and Chemical Permeability 0.1-110 m.sup.2
.times. 10.sup.15 Hydrogen Ion Concentration 4.5-10 Tear Strength
(Tappi 496, 402) 56-250 Tear Resistance (Tappi 414) m49-250
Moisture Content 2%-18% by Weight
[0100] 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 non-interspersed
mineral-containing layer. The number of extruders depends on the
number of different 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/EVA. Interspersed, e.g. monolayer, and
non-interspersed, 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.
[0101] 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, nano-cellulose, 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-00009 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 (1) LDPE HDPE
LDPE-HDPE resin LDPE-MMW LLDPE-LDPE PLA- bio blend HDPE resin resin
blend derived starch blend based resin blend Monolayer (2)
Bio-derived, LDPE-bio LDPE-LLDPE-bio LDPE-HDPE- PP-bio derived
ULDPE- starch derived starch derived starch blend LLDPE- blend
starch based HDPE-bio polymer polymer blend polymer blend derived
starch blend polymer blend 3-Layer HDPE- HDPE-PP HDPE-PET LDPE-PP
LLDPE-PET EVA-LDPE LDPE 4-Layer EVA- HDPE-EVA- Biaxially oriented
Oriented EVA-PE- PVC-ABS- ethylene Ionomer resin-
homopolypropylene- polypropylene- MMWHDPE- PC Nylon vinyl acetate
Polyamides- polyester- HDPE-PE- oriented EEA- polypropylene-PE
metallized PET polypropylene ethylene acrylic acid- HDPE-EAA
ethylene acrylic acid
[0102] Additionally, if relative 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,
polyvinylchrloride, polymethylpentene, methyl
methacrylate-acrylonitrile-butadiene-styrene,
acrylonitrile-styrene, poly carbonate, polystyrene, poly
methylcrylate, polyvynl pyrrolidone, ply (vinylpyrrolidone-co-vinyl
acetate), polyesters, parylene, polyethylene napphatalate, ethylene
vinyl alcohol, and polylactic 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
(non-interspersed) 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.
[0103] 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.
[0104] 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.
[0105] 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 TiO.sub.2, 2%-45% vinyl acrylic, and
from about 1% to about 35% protein binders, co-binders, or
tri-binders.
[0106] 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/m.sup.2 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 0 to about 1500 mls/min, as represented by the
Bendsten method.
TABLE-US-00010 TABLE 8 Fiber-Containing Layer Characteristics Tear
Fiber Weight Resistance Surface Burst (lbs/3 msf) g/m.sup.2 (Mn)
Roughness Strength (kPa) 40-75 60-110 400-700 2.0-5.5 .mu.m 140-300
>75 110-130 650-750 2.0-3.5 .mu.m 175-400 >115 180-190
1400-1900 100-2500 mls/min 175-475 >130 205-215 1600-2200
100-2500 mls/min 250-675 >200 315-330 1900-3200 100-2500 mls/min
500-950 >300 460-195 500-4000 100-2500 mls/min 700-1850
[0107] 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-00011 TABLE 9 Barrier Values of Formed Composite Structure
Test Method TAPPI T441 TAPPI T464 TAPPI T410 Tappi T559 Test Name
Cobb Water Absorption WVTR in Tropical Conditions Mineral layer Wgt
Grease Resistance Units g/m.sup.2 g/m.sup.2 g/100 in.sup.2
g/m.sup.2 lb/1000 ft.sup.2 3M Kit Test # Sample 2 minute 30 minute
Coated Uncoated # Fiber Layer Cobb Cobb Side Side 1 Recycled Fiber
.28 mil caliper 0.22 -- 23.4 1.51 *12 **1- 2 Virgin Fiber .20 mil
caliper 0.40 0.00 15.2 0.98 32.3 4.12 12 1- 3 Recycled Fiber .20
mil caliper 0.00 -- 18.6 1.20 3.45 12 1- 4 85-100% Recycled .20 mil
caliper 0.10 0.05 13.9 0.89 18.25 3.55 12 1- Fiber 5 Virgin-TMP
content .30 mil caliper -- -- 7.58 0.49 12 1- 6 Clay coated 1 side-
.18 mil caliper -- 0.45 7.13 0.46 7.5 12 1- bleached 7 Fiber 2-side
.18 mil caliper 0.00 -- 9.31 0.60 6.44 12 1- bleached 8 Fiber 1
side, .18 mil caliper 0.50 0.11 37.7 2.43 11.33 12 1- bleached 9
Virgin Kraft- .16 mil caliper 0.05 0.11 15.0 0.97 3.94 12 1- clay
coated 10 Virgin Kraft- .14 mil thick 0.00 0.10 14.1 0.91 28.1 3.89
12 1- clay coated 11 Clay coated un- .18 mil caliper 0.00 0.05 13.0
0.84 6.2 12 1- bleached kraft- 100% virging 12 Solid Unbleached .18
mil caliper 0.00 0.00 9.49 0.61 52.2 5.5 12 1- Sulfate Note: 1 mil
=1/1000th of an inch
[0108] 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-00012 TABLE 10 Barrier Values of a Formed Composite
Structure, Interspersed (Mono), Mineral-Containing Layer Monolayer
40%-60% Mineral Content (HDPE-PE MIX) WVTR in Tropical Conditions
Fiber type Cobb Water Absorption 100.degree. F./90% R.H. Mineral
layer weight Unit g/m.sup.2 g/m.sup.2 g/100 in.sup.2 g/m.sup.2
lb/1000 ft.sup.2 Sample 2-min 30-min 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
[0109] 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-00013 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 Perormance Table
Fiber Layer--Outer layer Pre Score + Bed Post Score Weight Ethylene
Co-Polymer Uncoated Mineral Ranges WVTR-Tropical WVTR WVTR Ranges
Mineral Layer Density - - - % Amorphous Box board 38-65%
gm/mm.sup.2 day Variation gm/mm.sup.2 day Variation Range 1.22-1.41
g/cm.sup.3 25%-65% 20 pt. Klabin 2 + layer coex 5 to 13 0.20 11 to
17 0.2 15 gsm 50 gsm 1.22-1.36 g/cm.sup.3 25-70% 20 pt. Klabin
Monolayer 8 to 22 0.2 14 to 25 0.2 15 gsm 50 gsm
[0110] FIG. 1 is a schematic side cross-sectional view of a
multilayer 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. FIG. 1A is a detail view of the portion of FIG. 1
indicated by the circle 1A-1A. As shown in FIG. 1A, 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 FIG. 1A, 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.
[0111] 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 FIG. 1 may advantageously be used as a
single or multiple corrugate liner(s) or medium(s) within a
single-layered or multilayered corrugated structure.
[0112] 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.
[0113] 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.
[0114] 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.
[0115] 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.
[0116] 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 therebetween.
[0117] 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
[0118] 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/cm.sup.3. 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/m.sup.2
weight Klabin virgin paper surface having a TAPPI 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/m.sup.2/24 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 16.64 g/m.sup.2/24 hrs, with a standard deviation of
1.41.
Example 2
[0119] 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 Term 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 post-extrusion 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
converted and 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
[0120] 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 T211, 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 CaCO.sub.3 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 post-extrusion 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
[0121] 1. Ash Content
[0122] Ash content was measured following Tappi standard T413. The
time at maximum temperature was extended to eight hours to ensure
complete ash.
TABLE-US-00014 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
[0123] 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%.
[0124] 2. Repulpability
[0125] Around 25 g of oven dried paper samples were torn 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-00015 TABLE 13 Repulpability Data of the Paper Samples
Screen Overall Sample Start 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 #5 26.235 20.700 2.044 78.90 86.69
[0126] The samples were disintegrated for 70,000 revolutions. It is
contemplated that the values shown in Table 13 above may vary by
about .+-.50%.
[0127] 3. Determination of Fibers, Plastics, and Ash
Compositions--Determined Ash Content of the Fraction Following the
Procedure Stated in 1 (Above)
[0128] 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. C. heating 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.
[0129] 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.
[0130] 4. Stickies Analysis
[0131] 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.
[0132] 5. Fate of Rosin Acids
[0133] 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 in-house libraries. Peak
area was used to anticipate the total mass of rosin acids.
[0134] 6. Starch Detection
[0135] 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.
[0136] Results
[0137] 1. Repulpability
[0138] 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-00016 TABLE 14 Repulpability Data of the Paper Samples
Repulpability Start Accepts, Rejects, Washout, Accepts Overall
pulp, g g g g Yield, % Yield, % 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
[0139] Results indicated that the accepts yield for all studied
samples is close to 80%. Sample CS-1 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%.
[0140] 2. Compositions of the Three Fractions
[0141] 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.
[0142] Table 15, below, lists the experimental results indicating
the percentage of each fraction in each sample.
TABLE-US-00017 TABLE 15 Percent Compositions of the Three Fractions
Accepts Rejects Wash-out Sample Ash Fibers Plastics Ash Fibers
Plastics Ash Fibers Plastics Ash CS-1 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) 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%.
[0143] In order to obtain reliable results, analysis to accepts of
sample CLWR-2 and CLWR-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-1, 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-1, whereas those among CS-1, 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, CLWR-2 and CLWR-8.1 have
increasingly amounts of inorganics 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-1 and IP MIX. Sample
CLWR-2 and CLWR-8.1 have increasingly amounts of inorganics,
probably presented as colloid particles in the washing liquor.
[0144] 3. Stickies Analysis
[0145] Impurities in the accepts are the major concern in 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-00018 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
detected + + Not detected +
[0146] 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 100% 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%.
[0147] Results 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.sup.2. 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 dirties 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-1, IP
MIX, CLWR 8.1 CLW 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, T815, T826, T403,
T831, T537, T277, T563.
[0148] 4. Fate of Rosin Acids
[0149] 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.
[0150] Results of GC/MS analysis to the three fractions from sample
CLWR-2 and CLWR-8.1 are shown in FIG. 7. FIG. 8 illustrates a
typical total ion spectrum of the DCM extract.
[0151] 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%.
[0152] 5. The Whereabouts of Starch
[0153] Starch's whereabouts among the three fractions is determined
by iodine detection. It is well known that starch will turn 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
[0154] 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
(msf) 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 100% 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 predominently 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 particles
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.
[0155] The composite structures described herein are well suited to
be formed into containers of various types. For example, FIG. 9
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. 9, 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 fold-over lid portion 66.
[0156] 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. 10. 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 formed 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.
[0157] 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.
[0158] 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.
[0159] 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.
[0160] 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 of the invention as generally
expressed by the following claims, which particularly point out and
distinctly claim the subject matter of the invention.
* * * * *