U.S. patent application number 13/657914 was filed with the patent office on 2013-04-25 for dispersions of higher crystallinity olefins.
This patent application is currently assigned to Dow Global Technologies LLC. The applicant listed for this patent is Dow Global Technologies LLC. Invention is credited to Neil W. Dunchus, Matthew J. Kalinowski, Kevin D. Maak, Anthony C. Neubauer, Albert Quaranta, Gary M. Strandburg.
Application Number | 20130101847 13/657914 |
Document ID | / |
Family ID | 40329369 |
Filed Date | 2013-04-25 |
United States Patent
Application |
20130101847 |
Kind Code |
A1 |
Neubauer; Anthony C. ; et
al. |
April 25, 2013 |
DISPERSIONS OF HIGHER CRYSTALLINITY OLEFINS
Abstract
Dispersions and methods for forming dispersions that include a
higher crystallinity polyolefin and at least one dispersing agent
are disclosed. Various applications for use of the dispersions are
also disclosed.
Inventors: |
Neubauer; Anthony C.;
(Piscataway, NJ) ; Quaranta; Albert; (Sayreville,
NJ) ; Dunchus; Neil W.; (Kinnelon, NJ) ;
Kalinowski; Matthew J.; (Freeland, MI) ; Strandburg;
Gary M.; (Mt. Pleasant, MI) ; Maak; Kevin D.;
(Midland, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC; |
Midland |
MI |
US |
|
|
Assignee: |
Dow Global Technologies LLC
Midland
MI
|
Family ID: |
40329369 |
Appl. No.: |
13/657914 |
Filed: |
October 23, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12680502 |
Mar 26, 2010 |
8318257 |
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PCT/US08/76758 |
Sep 18, 2008 |
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13657914 |
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60976255 |
Sep 28, 2007 |
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Current U.S.
Class: |
428/396 ;
427/385.5; 521/143; 521/144; 524/570; 524/585 |
Current CPC
Class: |
C08J 3/05 20130101; B29K
2023/00 20130101; G03G 9/083 20130101; G03G 9/0804 20130101; G03G
9/08797 20130101; C08J 9/30 20130101; C08J 2205/05 20130101; D21H
21/20 20130101; D06M 15/227 20130101; C03C 25/30 20130101; D21H
17/35 20130101; C08J 2323/02 20130101; C08J 2323/08 20130101; B29B
15/12 20130101; C08L 23/00 20130101; G03G 9/08704 20130101; C09D
123/04 20130101; Y10T 428/2971 20150115; C08L 23/02 20130101; D21H
19/58 20130101; C08L 23/0869 20130101; C08L 23/00 20130101; C08L
2666/06 20130101; C08L 23/02 20130101; C08L 2666/06 20130101; C08L
23/0869 20130101; C08L 2666/06 20130101 |
Class at
Publication: |
428/396 ;
427/385.5; 524/585; 524/570; 521/143; 521/144 |
International
Class: |
C09D 123/04 20060101
C09D123/04 |
Claims
1-3. (canceled)
14. A method of forming an aqueous dispersion, comprising: melt
kneading (A) at least one higher crystallinity polyolefin, having a
crystallinity of greater than 50 percent, and (B) at least one
stabilizing agent, to produce a melt-kneaded product; diluting the
melt-kneaded product with water; and melt kneading the resulting
mixture to form the dispersion; wherein the polyolefin comprises an
ethylene hompolymer, an ethylene/.alpha.-olefin copolymer, an
ethylene/.alpha.-olefin multiblock interpolymer; or combinations of
two or more thereof.
15. The method of claim 14, wherein the melt kneading comprises
forming the aqueous dispersion in an extrusion apparatus comprising
a variable high internal phase emulsion creation zone, the method
further comprising controlling an extrusion apparatus outlet
pressure via a self-cleaning micro-notch V-ball control valve.
16. A foam produced from a dispersion prepared by the method of
claim 14.
17. The foam of claim 16, having a compression set at 85.degree.
C., 20 minutes, at a pressure of 0.5 psig of less than 70
percent.
18. The foam of claim 16, comprising cells having a size range from
about 5 micrometers diameter to about 1000 micrometers
diameter.
19. The foam of claim 18, wherein the cells comprise open
cells.
20. The foam of claim 16, wherein the dispersion has a viscosity of
not more than about 50,000 cP at 25.degree. C.
21-22. (canceled)
23. An article formed by a process comprising: impregnating a
fibrous structure with a compound; the compound comprising an
aqueous dispersion, the dispersion comprising; at least one higher
crystallinity polyolefin, having a crystallinity greater than 50
percent; at least one dispersing agent; and water; and wherein the
polyolefin comprises an ethylene hompolymer, an
ethylene/.alpha.-olefin copolymer, an ethylene/.alpha.-olefin
multiblock interpolymer; or combinations thereof.
24. A coated fiber comprising; a compound in contact with a portion
of a fiber, wherein the compound at the time of contacting a higher
crystallinity polyolefin; and at least one higher crystallinity
polyolefin, having a crystallinity greater than 50 percent; at
least one dispersing agent; and water; and wherein the polyolefin
comprises an ethylene hompolymer, an ethylene/.alpha.-olefin
copolymer, an ethylene/.alpha.-olefin multiblock interpolymer; or
combinations thereof, wherein the fiber has a diameter between 5
and 35 microns; and wherein a thickness of a coating layer of the
compound on the fiber ranges from about 0.1 to 10 microns.
25-33. (canceled)
Description
BACKGROUND OF INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates generally to dispersions of
olefins.
[0003] 2. Background
[0004] Aqueous dispersions of a thermoplastic resin of various
types are known in the art and have been used in a wide variety of
fields. For example, when an aqueous dispersion is coated and dried
on a surface of a substrate such as paper, fiber, wood, metal, or
plastic molded article, the resin coating formed will provide the
substrate with water resistance, oil resistance, chemical
resistance, corrosion resistance and heat sealability. An aqueous
medium is advantageous compared to an organic dispersion medium in
view of common hazards such as flammability, working environment,
handling convenience, and the like.
[0005] Conventional aqueous dispersions of a thermoplastic resin
have been produced either by a process wherein a polymerizable
monomer which is the resin raw material is polymerized by emulsion
polymerization in an aqueous medium in the presence of a dispersing
agent, or by a process wherein a molten thermoplastic resin and an
aqueous medium, and optionally a dispersing agent are mixed by
applying shearing force.
[0006] Until the advent of polyolefin dispersions, polyolefins were
typically limited to extrusion and coextrusion processes and thus
polyolefins could not be used in coating processes such as paper
coating, fabric coating, and the like, nor in very thin layers,
e.g., less than 15 microns.
[0007] Newer polyolefin dispersions have provided improved
performance, but the useful polyolefin dispersions have been
limited to those with lower crystallinities, such as ethylene and
propylene elastomers and plastomers. Exemplary aqueous dispersions
of this sort are disclosed in U.S. Patent Application Publication
No. 2005/0100754, which is assigned to the assignee of the present
invention. Alternatively, higher crystallinity polyolefins have
been dispersed in water, but have required the presence of
solvents.
[0008] Accordingly, there exists a need for dispersions and foams
formed from higher crystallinity thermoplastic polymers, especially
olefin-based polymers, where the dispersions are preferably formed
without the use of solvents.
SUMMARY OF INVENTION
[0009] In one aspect, embodiments disclosed herein relate to
aqueous dispersions including: at least one higher crystallinity
thermoplastic; at least one dispersing agent; and water.
[0010] In another aspect, embodiments disclosed herein relate to a
method of forming an aqueous dispersion, including: melt kneading
(A) at least one higher crystallinity polyolefin, and (B) at least
one stabilizing agent, to produce a melt-kneaded product; diluting
the melt-kneaded product with water; and melt kneading the
resulting mixture to form the dispersion.
[0011] In another aspect, embodiments disclosed herein relate to a
method of forming a foam, including: contacting the dispersion of
claim 1 with air or other inert gas to form a whipped dispersion;
depositing the whipped dispersion onto a substrate; and at least
partially drying the whipped dispersion to form a foam, wherein the
whipped dispersion is formed at a temperature less than the melting
point of the dispersed polymer.
[0012] In another aspect, embodiments disclosed herein relate to a
cellulose-based article including: a cellulose-based composition;
and an applied compound, wherein the applied compound, at the time
of application, comprises an aqueous dispersion including: a higher
crystallinity polyolefin; and at least one dispersing agent.
[0013] In another aspect, embodiments disclosed herein relate to
articles formed by a process including: impregnating a fibrous
structure with a compound, the compound comprising an aqueous
dispersion, the dispersion comprising a higher crystallinity
polyolefin; and at least one dispersing agent, removing at least a
portion of the water from the impregnated fibrous structure.
[0014] In another aspect, embodiments disclosed herein relate to
coated fibers including: a compound in contact with a portion of a
fiber, wherein the compound at the time of contacting comprised an
aqueous dispersion comprising: a higher crystallinity polyolefin;
and at least one dispersing agent, wherein the fiber has a diameter
between 5 and 35 microns; and wherein a thickness of a coating
layer of the compound on the fiber ranges from about 0.1 to 10
microns.
[0015] In another aspect, embodiments disclosed herein relate to a
toner composition including: a particulate made from an aqueous
dispersion, the dispersion comprising: a higher crystallinity
polyolefin; and at least one dispersing agent, and at least one
selected from the group consisting of a colorant and a magnetic
pigment, wherein the dispersion has an average volume diameter
particle size from about 0.3 to about 8 microns, wherein the
dispersion has at least been partially dried such that the liquid
level is at least 50 percent that of the liquid level of the
dispersion to form the particulate.
[0016] In another aspect, embodiments disclosed herein relate to a
method for forming a layer on a substrate comprising: applying an
aqueous dispersion to a substrate, the dispersion comprising: a
higher crystallinity polyolefin; at least one dispersing agent;
removing at least a portion of water in the dispersion to form a
first layer.
[0017] In another aspect, embodiments disclosed herein relate to a
method to make a long fiber concentrate comprising fibers and a
thermoplastic resin comprising the steps of: i) coating continuous
fibers with an aqueous dispersion to form thermoplastic coated
continuous fiber strands, wherein the dispersion comprises: a
higher crystallinity polyolefin and at least one dispersing agent;
ii) heating the thermoplastic coated continuous fiber strands, iii)
chopping the dried thermoplastic coated continuous fiber strands
forming dried long fiber concentrate pellets, and iv) isolating
dried long fiber concentrate pellets.
[0018] In another aspect, embodiments disclosed herein relate to a
method to make a long fiber concentrate comprising fibers and a
thermoplastic resin comprising the steps of: i) coating chopped
long fibers with an aqueous dispersion to form thermoplastic coated
chopped fiber pellets, wherein the dispersion comprises a higher
crystallinity polyolefin and at least one dispersing agent; ii)
heating the coated chopped long fiber concentrate pellets, and iii)
isolating dried long fiber concentrate pellets.
[0019] Other aspects and advantages of the invention will be
apparent from the following description and the appended
claims.
BRIEF DESCRIPTION OF DRAWINGS
[0020] FIG. 1 is a schematic representation of a typical
melt-extrusion apparatus used to prepare embodiments of the
invention.
[0021] FIG. 2 is a schematic representation of a typical
melt-extrusion apparatus used to prepare embodiments of the
dispersions disclosed herein, according to embodiments of the
invention.
[0022] FIG. 3A is a chart illustrating the performance of an
unmodified melt extrusion device, similar to that of FIG. 1,
graphically depicting extruder operating pressures over time.
[0023] FIG. 3B is a chart illustrating the performance of a
modified melt extrusion device according to embodiments disclosed
herein, similar to that of FIG. 2, graphically depicting extruder
operating pressures over time.
[0024] FIG. 4 is a chart comparing neutralizing agent feed rates
for an unmodified extrusion apparatus and a modified extrusion
apparatuses according to embodiments disclosed herein.
DETAILED DESCRIPTION
[0025] As used herein, the term "higher crystallinity
thermoplastic," preferably a polyolefin means a thermoplastic
having a crystallinity of at least 46% and, preferably a density
greater than or equal to 0.915 g/cc. As used herein, the term
"lower crystallinity thermoplastic," preferably a polyolefin, means
a thermoplastic having a crystallinity of less than 46%, regardless
of density. In various embodiments, higher crystallinity
polyolefins may have a density of at least 0.920 g/cc, at least
0.925 g/cc, at least 0.930 g/cc, at least 0.940 g/cc, at least
0.945 g/cc, at least 0.950 g/cc, at least 0.955 g/cc, at least
0.960 g/cc, or at least 0.965 g/cc (density is measured in
accordance with ASTM D 792). In other various embodiments, higher
crystallinity polyolefins may have a crystallinity of at least 49
percent, at least 50 percent, at least 52 percent, at least 56
percent, at least 62 percent, at least 65 percent, at least 69
percent, at least 72 percent, at least 75 percent or at least 78
percent. Preferably, the higher crystallinity thermoplastics may
have weight average molecular weights, M.sub.w, for example,
ranging from a lower limit of 15,000 g/mole, 30,000 g/mole,
preferably 50,000 g/mole to an upper limit of about 5,000,000
g/mole, preferably to about 2,500,000, and especially to about
1,000,000 in some embodiments; from 1000 g/mole to 1,000,000 g/mole
in other embodiments; from 10,000 g/mole to 500,000 g/mole in other
embodiments; and from 10,000 g/mole to 300,000 g/mole in yet other
embodiments. For example, polyolefin polymers having a
crystallinity of about 55% and higher with a from about 15,000 to
about 1,000,000 g/mole are especially preferred.
[0026] Other embodiments disclosed herein relate to an apparatus
for forming a polymer dispersion. More specifically, embodiments
disclosed herein relate to an extruder or art extrusion system
useful for forming polymer dispersions, such as polyolefin
dispersions. In another aspect, embodiments disclosed herein relate
to a kneading disk useful in an extrusion system for forming
polymer dispersions. Apparatuses for forming dispersions herein may
be used to produce aqueous (having a water-based dispersion medium)
or non-aqueous dispersion (having an oleaginous or
hydrocarbon-based dispersion medium).
[0027] "Polymer" means a polymeric compound prepared by
polymerizing monomers, whether of the same or a different type. The
generic term "polymer" embraces the terms "homopolymer,"
"copolymer," "terpolymer," as well as "interpolymer."
[0028] "Interpolymer" means a polymer prepared by the
polymerization of at least two different types of monomers. The
generic term "interpolymer" includes the term "copolymer" (which is
usually employed to refer to a polymer prepared from two different
monomers) as well as the term "terpolymer" (which is usually
employed to refer to a polymer prepared from three different types
of monomers). It also encompasses polymers made by polymerizing
four or more types of monomers.
[0029] The terms "ethylene/.alpha.-olefin interpolymer" and
"propylene/.alpha.-olefin interpolymer" refer to polymers with
ethylene or propylene, respectively, being the majority mole
fraction of the whole polymer. In some embodiments, the majority
monomer may comprise at least 50 mole percent of the whole polymer;
at least 60 mole percent in other embodiments; at least 70 mole
percent in other embodiments; and at least 80 mole percent in yet
other embodiments. The remainder of the whole polymer comprising at
least one comonomer. In some embodiments, ethylene/.alpha.-olefin
interpolymers include ethylene at a content of greater than about
80 mole percent, and an .alpha.-olefin content of equal to or less
than about 20 mole percent.
[0030] In one aspect, embodiments disclosed herein relate to an
aqueous dispersion composition including at least one polyolefin
with a density greater than 0.915 g/cc, e.g., LDPE or HDPE
homopolymer, ethylene/alpha-olefin LLDPE or HDPE copolymers, PP
homopolymer, PP random and impact copolymers, propylene-ethylene
copolymers, and a dispersing agent.
[0031] More specifically, selected embodiments disclosed that
involve a polyethylene component have a melt index (I.sub.2 at
190.degree. C.) (melt index is measured in accordance with ASTM D
1238, condition 190 C/2.16 kg) ranging from 0.5 dg/min to 30
dg/min. Moreover, in select embodiments the dispersion composition
may also include at least one surfactant agent, such as PRIMACOR
5980I, at 3 wt % to 50 wt %. Still further, in select embodiments,
a neutralizing agent may be used. Specifically, KOH, NH.sub.4OH and
NaOH may be used as neutralizing agents and dosed at 50% to 100%
neutralization. In select embodiments, the final solids
concentration should be between 30% (wt/wt) to 60% (wt/wt).
[0032] Embodiments disclosed herein may include mixtures or blends
of multiple polymers, so long as at least one of the dispersed
polymers is a higher crystallinity olefin. For example, it is
specifically within the scope of the present disclosure that
dispersions of higher crystallinity olefins may be blended with
dispersions of lower crystallinity olefins. Similarly, multiple
different higher crystallinity olefins and/or multiple different
lower crystallinity olefins may be used in conjunction with each
other.
[0033] Polyolefins
[0034] In specific embodiments, the thermoplastic polymers or
non-polar thermoplastic polyolefins may include polyolefins such as
polypropylene, polyethylene, and copolymers thereof, and blends
thereof, as well as ethylene-propylene-diene terpolymers. In some
embodiments, preferred olefinic polymers include homogeneous
polymers described in U.S. Pat. No. 3,645,992; high density
polyethylene (HDPE) as described in U.S. Pat. No. 4,076,698;
homogeneously branched, linear ethylene/.alpha.-olefin copolymers;
homogeneously branched, substantially linear
ethylene/.alpha.-olefin polymers, which may be prepared, for
example, by a process disclosed in U.S. Pat. Nos. 5,272,236 and
5,278,272, the disclosures of which are incorporated herein by
reference; and high pressure, free radical polymerized ethylene
polymers and copolymers such as low density polyethylene
(LDPE).
[0035] Polymer compositions described in U.S. Pat. No. 6,566,446,
6,538,070, 6,448,341, 6,316,549, 6,111,023, 5,869,575, 5,844,045,
or 5,677,383, each of which is incorporated herein by reference in
its entirety, are also suitable in some embodiments. Of course,
blends of polymers may be used as well. In some embodiments, the
blends include two different Ziegler-Natta polymers. In other
embodiments, the blends may include blends of a Ziegler-Natta and a
metallocene polymer. In still other embodiments, the polymer used
herein may be a blend of two different metallocene polymers. In
other embodiments polymers produced from single site catalysts may
be used. In yet another embodiment, block or multi-block copolymers
may be used in embodiments of the invention. Such polymers include
those described and claimed in WO2005/090427 (having priority to
U.S. Ser. No. 60/553,906, filed Mar. 7, 2004).
[0036] Thus, in select embodiments, exemplary polymers include
polypropylene (both impact modifying polypropylene, isotactic
polypropylene, atactic polypropylene, and random ethylene/propylene
copolymers), various types of polyethylene, including high
pressure, free-radical LDPE, Ziegler Natta LLDPE, metallocene PE,
including multiple reactor PE ("in reactor" blends of Ziegler-Natta
PE and metallocene PE, such as products disclosed in U.S. Pat. Nos.
6,545,088, 6,538,070, 6,566,446, 5,844,045, 5,869,575, and
6,448,341), ethylene-vinyl acetate (EVA), ethylene/vinyl alcohol
copolymers, polystyrene, impact modified polystyrene, ABS,
styrene/butadiene block copolymers and hydrogenated derivatives
thereof (SBS and SEBS).
[0037] In some particular embodiments, the polymer is a
propylene-based copolymer or interpolymer. In some embodiments, the
propylene-based copolymer or interpolymer is characterized as
having substantially isotactic propylene sequences. The term
"substantially isotactic propylene sequences" and similar terms
mean that the sequences have an isotactic triad (mm) measured by
.sup.13C NMR of greater than about 0.85, preferably greater than
about 0.90, more preferably greater than about 0.92 and most
preferably greater than about 0.93. Isotactic triads are well-known
in the art and are described in, for example, U.S. Pat. No.
5,504,172 and WO 00/01745, which refer to the isotactic sequence in
terms of a triad unit in the copolymer molecular chain determined
by .sup.13C NMR spectra.
[0038] In other particular embodiments, the thermoplastic polymer
may be ethylene vinyl acetate (EVA) based polymers. In other
embodiments, the thermoplastic polymer may be ethylene-methyl
acrylate (EMA) based polymers. In other particular embodiments, the
ethylene-.alpha. olefin copolymer may be ethylene-butene,
ethylene-hexene, or ethylene-octene copolymers or interpolymers. In
other particular embodiments, the propylene-.alpha. olefin
copolymer may be a propylene-ethylene or a
propylene-ethylene-butene copolymer or interpolymer.
[0039] Dispersions formed in accordance with other embodiments may
also include fillers and additives. In addition, embodiments of the
present invention may also use multi-block olefin interpolymers
having suitable densities and/or crystallinities, as those polymers
are described below.
[0040] Multi-Block Olefin Interpolymer
[0041] As described above, embodiments of the dispersions disclosed
herein may include a polymeric component that may include at least
one multi-block olefin interpolymer. The following definitions are
provided to distinguish a multi-block olefin interpolymer from
other olefin polymers.
[0042] The term "multi-block copolymer" or "segmented copolymer"
refers to a polymer comprising two or more chemically distinct
regions or segments (referred to as "blocks") preferably joined in
a linear manner, that is, a polymer comprising chemically
differentiated units which are joined end-to-end with respect to
polymerized ethylenic functionality, rather than in pendent or
grafted fashion. In certain embodiments, the blocks differ in the
amount or type of comonomer incorporated therein, the density, the
amount of crystallinity, the crystallite size attributable to a
polymer of such composition, the type or degree of tacticity
(isotactic or syndiotactic), regio-regularity or
regio-irregularity, the amount of branching, including long chain
branching or hyper-branching, the homogeneity, or any other
chemical or physical property.
[0043] The multi-block copolymers are characterized by unique
distributions of polydispersity index (PDI or M.sub.w/M.sub.n),
block length distribution, and/or block number distribution due to
the unique process making of the copolymers. More specifically,
when produced in a continuous process, embodiments of the polymers
may possess a PDI ranging from about 1.7 to about 8; from about 1.7
to about 3.5 in other embodiments; from about 1.7 to about 2.5 in
other embodiments; and from about 1.8 to about 2.5 or from about
1.8 to about 2.1 in yet other embodiments. When produced in a batch
or semi-batch process, embodiments of the polymers may possess a
PDI ranging from about 1 to about 2.9; from about 1.3 to about 2.5
in other embodiments; from about 1.4 to about 2 in other
embodiments; and from about 1.4 to about 1.8 in yet other
embodiments.
[0044] One example of the multi-block olefin interpolymer is an
ethylene/.alpha.-olefin block interpolymer. Another example of the
multi-block olefin interpolymer is a propylene/.alpha.-olefin
interpolymer. The following description focuses on the interpolymer
as having ethylene as the majority monomer, but applies in a
similar fashion to propylene-based multi-block interpolymers with
regard to general polymer characteristics.
[0045] The ethylene/.alpha.-olefin multi-block interpolymers
(hereinafter "ethylene/.alpha.-olefin interpolymer" or variations
thereof) comprise ethylene and one or more co-polymerizable
.alpha.-olefin comonomers in polymerized form, characterized by
multiple (i.e., two or more) blocks or segments of two or more
polymerized monomer units differing in chemical or physical
properties (block interpolymer), preferably a multi-block
interpolymer. In some embodiments, the multi-block interpolymer may
be represented by the following formula:
(AB).sub.n
where n is at least 1, preferably an integer greater than 1, such
as 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, or
higher; "A" represents a hard block or segment; and "B" represents
a soft block or segment. Preferably, A's and B's are linked in a
linear fashion, not in a branched or a star fashion. "Hard"
segments refer to blocks of polymerized units in which ethylene is
present in an amount greater than 95 weight percent in some
embodiments, and in other embodiments greater than 98 weight
percent. In other words, the comonomer content in the hard segments
is less than 5 weight percent in some embodiments, and in other
embodiments, less than 2 weight percent of the total weight of the
hard segments. In some embodiments, the hard segments comprise all
or substantially all ethylene. "Soft" segments, on the other hand,
refer to blocks of polymerized units in which the comonomer content
is greater than 5 weight percent of the total weight of the soft
segments in some embodiments, greater than 8 weight percent,
greater than 10 weight percent, or greater than 15 weight percent
in various other embodiments. In some embodiments, the comonomer
content in the soft segments may be greater than 20 weight percent,
greater than 25 eight percent, greater than 30 weight percent,
greater than 35 weight percent, greater than 40 weight percent,
greater than 45 weight percent, greater than 50 weight percent, or
greater than 60 weight percent in various other embodiments.
[0046] In some embodiments, A blocks and B blocks are randomly
distributed along the polymer chain. In other words, the block
copolymers do not have a structure like:
AAA-AA-BBB-BB
[0047] In other embodiments, the block copolymers do not have a
third block. In still other embodiments, neither block A nor block
B comprises two or more segments (or sub-blocks), such as a tip
segment.
[0048] The ethylene/.alpha.-olefin interpolymers are characterized
by an average block index, ABI, ranging from greater than zero to
about 1.0 and a molecular weight distribution, M.sub.w/M.sub.n,
greater than about 1.3. The average block index, ABI, is the weight
average of the block index ("BI") for each of the polymer fractions
obtained in preparative TREF (temperature rising elution
fractionation) from 20.degree. C. and 110.degree. C., with an
increment of 5.degree. C.:
ABI=.SIGMA.(w.sub.iBI.sub.i)
where BI.sub.i is the block index for the i.sup.th fraction of the
ethylene/.alpha.-olefin interpolymer obtained in preparative TREF,
and w.sub.i is the weight percentage of the i.sup.th fraction.
[0049] Similarly, the square root of the second moment about the
mean, hereinafter referred to as the second moment weight average
block index, may be defined as follows:
2 nd moment weight average BI = ( w i ( BI i - ABI ) 2 ) ( N - 1 )
w i N ##EQU00001##
[0050] For each polymer fraction, BI is defined by one of the two
following equations (both of which give the same BI value):
BI = 1 / T X - 1 / T XO 1 / T A - 1 / T AB or ##EQU00002## BI = -
Ln P x - Ln P XO Ln P A - Ln P AB ##EQU00002.2##
where T.sub.X is the analytical temperature rising elution
fractionation (ATREF) elution temperature for the i.sup.th fraction
(preferably expressed in Kelvin), P.sub.X is the ethylene mole
fraction for the i.sup.th fraction, which may be measured by NMR or
IR as described below. P.sub.AB is the ethylene mole fraction of
the whole ethylene/.alpha.-olefin interpolymer (before
fractionation), which also may be measured by NMR or IR. T.sub.A
and P.sub.A are the ATREF elation temperature and the ethylene mole
fraction for pure "hard segments" (which refer to the crystalline
segments of the interpolymer). As an approximation or for polymers
where the "hard segment" composition is unknown, the T.sub.A and
P.sub.A values are set to those for high density polyethylene
homopolymer.
[0051] T.sub.AB is the ATREF elution temperature for a random
copolymer of the same composition (having an ethylene mole fraction
of P.sub.AB) and molecular weight as the multi-block interpolymer.
T.sub.AB may be calculated from the mole fraction of ethylene
(measured by NMR) using the following equation:
Ln P.sub.AB=.alpha./T.sub.AB+.beta.
where .alpha. and .beta. are two constants which may be determined
by a calibration using a number of well characterized preparative
TREF fractions of a broad composition random copolymer and/or well
characterized random ethylene copolymers with narrow composition.
It should be noted that .alpha. and .beta. may vary from instrument
to instrument. Moreover, one would need to create an appropriate
calibration curve with the polymer composition of interest, using
appropriate molecular weight ranges and comonomer type for the
preparative TREF fractions and/or random copolymers used to create
the calibration. There is a slight molecular weight effect. If the
calibration curve is obtained from similar molecular weight ranges,
such effect would be essentially negligible. In some embodiments,
random ethylene copolymers and/or preparative TREF fractions of
random copolymers satisfy the following relationship:
Ln P=-237.83/T.sub.ATREF+0.639
[0052] The above calibration equation relates the mole fraction of
ethylene, P, to the analytical TREF elution temperature,
T.sub.ATREF, for narrow composition random copolymers and/or
preparative TREF fractions of broad composition random copolymers.
T.sub.XO is the ATREF temperature for a random copolymer of the
same composition and having an ethylene mole fraction of P.sub.X.
T.sub.XO may be calculated from LnP.sub.X=.alpha./T.sub.XO+.beta..
Conversely, P.sub.XO is the ethylene mole fraction for a random
copolymer of the same composition and having an ATREF temperature
of T.sub.X, which may be calculated from Ln
P.sub.XO=.alpha./T.sub.X+.beta..
[0053] Once the block index (BI) for each preparative TREF fraction
is obtained, the weight average block index, ABI, for the whole
polymer may be calculated. In some embodiments, ABI is greater than
zero but less than about 0.4 or from about 0.1 to about 0.3. In
other embodiments, ABI is greater than about 0.4 and up to about
1.0. Preferably, ABI should be in the range of from about 0.4 to
about 0.7, from about 0.5 to about 0.7, or from about 0.6 to about
0.9. In some embodiments, ABI is in the range of from about 0.3 to
about 0.9, from about 0.3 to about 0.8, or from about 0.3 to about
0.7, from about 0.3 to about 0.6, from about 0.3 to about 0.5, or
from about 0.3 to about 0.4. In other embodiments, ABI is in the
range of from about 0.4 to about 1.0, from about 0.5 to about 1.0,
or from about 0.6 to about 1.0, from about 0.7 to about 1.0, from
about 0.8 to about 1.0, or from about 0.9 to about 1.0.
[0054] Another characteristic of the ethylene/.alpha.-olefin
interpolymer is that the ethylene/.alpha.-olefin interpolymer
comprises at least one polymer fraction which may be obtained by
preparative TREF, wherein the fraction has a block index greater
than about 0.1 and up to about 1.0 and the polymer having a
molecular weight distribution, M.sub.w/M.sub.n, greater than about
1.3. In some embodiments, the polymer fraction has a block index
greater than about 0.6 and up to about 1.0, greater than about 03
and up to about 1.0, greater than about 0.8 and up to about 1.0, or
greater than about 0.9 and up to about 1.0. In other embodiments,
the polymer fraction has a block index greater than about 0.1 and
up to about 1.0, greater than about 0.2 and up to about 1.0,
greater than about 0.3 and up to about 1.0, greater than about 0.4
and up to about 1.0, or greater than about 0.4 and up to about 1.0.
In still other embodiments, the polymer fraction has a block index
greater than about 0.1 and up to about 0.5, greater than about 0.2
and up to about 0.5, greater than about 0.3 and up to about 0.5, or
greater than about 0.4 and up to about 0.5. In yet other
embodiments, the polymer fraction has a block index greater than
about 0.2 and up to about 0.9, greater than about 0.3 and up to
about 0.8, greater than about 0.4 and up to about 0.7, or greater
than about 0.5 and up to about 0.6.
[0055] In addition to an average block index and individual
fraction block indices, the ethylene/.alpha.-olefin interpolymers
may be characterized by one or more of the properties described as
follows.
[0056] In one aspect, the ethylene/.alpha.-olefin interpolymers
used in embodiments of the invention have a M.sub.w/M.sub.n from
about 1.7 to about 3.5 and at least one melting point, T.sub.m, in
degrees Celsius and density, d, in grams/cubic centimeter, wherein
the numerical values of the variables correspond to the
relationship:
T.sub.m>-2002.9+4538.5(d)-2422.2(d).sup.2 in some
embodiments;
T.sub.m.gtoreq.-6288.1+13141(d)-6720.3(d).sup.2 in other
embodiments; and
T.sub.m.gtoreq.858.91-1825.3(d)+1112.8(d).sup.2 in yet other
embodiments.
[0057] Unlike the traditional random copolymers of
ethylene/.alpha.-olefins whose melting points decrease with
decreasing densities, the ethylene/.alpha.-olefins interpolymers
exhibit melting points substantially independent of the density,
particularly when density is between about 0.87 g/cc to about 0.95
g/cc. For example, the melting point of such polymers may be in the
range of about 110.degree. C. to about 130.degree. C. when density
ranges from 0.875 g/cc to about 0.945 g/cc. In some embodiments,
the melting point of such polymers may be in the range of about
115.degree. C. to about 125.degree. C. when density ranges from
0.875 g/cc to about 0.945 g/cc.
[0058] In another aspect, the ethylene/.alpha.-olefin interpolymers
comprise, in polymerized form, ethylene and one or more
.alpha.-olefins and are characterized by a .DELTA.T, in degree
Celsius, defined as the temperature for the tallest Differential
Scanning calorimetry ("DSC") peak minus the temperature for the
tallest Crystallization Analysis Fractionation ("CRYSTAF") peak and
a heat of fusion in J/g, .DELTA.H, and .DELTA.T and .DELTA.H
satisfy the following relationships:
.DELTA.T>-0.1299(.DELTA.H)+62.81 in some embodiments;
.DELTA.T>-0.1299(.DELTA.H)+64.38 in other embodiments; and
.DELTA.T>-0.1299(.DELTA.H)+65.95, in yet other embodiments,
for .DELTA.H up to 130 J/g. Moreover, .DELTA.T is equal to or
greater than 48.degree. C. for .DELTA.H greater than 130 J/g. The
CRYSTAF peak is determined using at least 5 percent of the
cumulative polymer (that is, the peak must represent at least 5
percent of the cumulative polymer), and if less than 5 percent of
the polymer has an identifiable CRYSTAF peak, then the CRYSTAF
temperature is 30.degree. C., and .DELTA.H is the numerical value
of the heat of fusion in J/g. More preferably, the highest CRYSTAF
peak contains at least 10 percent of the cumulative polymer.
[0059] In yet another aspect, the ethylene/.alpha.-olefin
interpolymers may have a molecular fraction which elutes between
40.degree. C. and 130.degree. C. when fractionated using
Temperature Rising Elution Fractionation ("TREF"), characterized in
that the fraction has a molar comonomer content higher, at least 5
percent higher in some embodiments, at least 10 percent higher in
other embodiments, than that of a comparable random ethylene
interpolymer fraction eluting between the same temperatures,
wherein the comparable random ethylene interpolymer contains the
same comonomer(s), and has a melt index, density, and molar
comonomer content (based on the whole polymer) within 10 percent of
that of the block interpolymer. In some embodiments, the Mw/Mn of
the comparable interpolymer is also within 10 percent of that of
the block interpolymer and/or the comparable interpolymer has a
total comonomer content within 10 weight percent of that of the
block interpolymer.
[0060] In still another aspect, the ethylene/.alpha.-olefin
interpolymers are characterized by an elastic recovery, Re, in
percent at 300 percent strain and 1 cycle measured on a
compression-molded film of an ethylene/.alpha.-olefin
interpolyrner, and has a density, d, in grams/cubic centimeter,
wherein the numerical values of Re and d satisfy the following
relationship when ethylene/.alpha.-olefin interpolymer is
substantially free of a cross-linked phase:
Re>1481-1629(d) in some embodiments;
Re.gtoreq.1491-1629(d) in other embodiments;
Re.gtoreq.1501-1629(d) in other embodiments; and
Re.gtoreq.1511-1629(d) in yet other embodiments.
[0061] In some embodiments, the ethylene/.alpha.-olefin
interpolymers may have a tensile strength above 10 MPa; a tensile
strength greater than 11 MPa in other embodiments; and a tensile
strength greater than 13 MPa in yet other embodiments. In some
embodiments, the ethylene/.alpha.-olefins interpolymers may have an
elongation at break of at least 600 percent at a crosshead
separation rate of 11 cm/minute; at least 700 percent in other
embodiments; at least 800 percent in other embodiments; and at
least 900 percent in yet other embodiments.
[0062] In some embodiments, the ethylene/.alpha.-olefin
interpolymers may have a storage modulus ratio, G'(25.degree.
C.)/G'(100.degree. C.), from 1 to 50; from 1 to 20 in other
embodiments; and from 1 to 10 in yet other embodiments. In some
embodiments, the ethylene/cc-olefin interpolymers may have a
70.degree. C. compression set of less than 80 percent; less than 70
percent in other embodiments; less than 60 percent in other
embodiments; and, less than 50 percent, less than 40 percent, down
to a compression set of 0 percent in yet other embodiments.
[0063] In some embodiments, the ethylene/.alpha.-olefin
interpolymers may have an 85.degree. C. compression set of less
than 80 percent; less than 70 percent in other embodiments; less
than 60 percent in other embodiments; and, less than 50 percent,
less than 40 percent, down to a compression set of 0 percent in yet
other embodiments.
[0064] In some embodiments, the ethylene/.alpha.-olefin
interpolymers may have a heat of fusion of less than 851/g. In
other embodiments, the ethylene/.alpha.-olefin interpolymer may
have a pellet blocking strength of equal to or less than 100
pound/ft.sup.2 (4800 Pa); equal to or less than 50 lb/ft.sup.2
(2400 Pa) in other embodiments; equal to or less than 5 lb/ft.sup.2
(240 Pa), and as low as 0 lb/ft.sup.2 (0 Pa) in yet other
embodiments.
[0065] In other embodiments, the ethylene/.alpha.-olefin
interpolymers may comprise, in polymerized form, at least 50 mole
percent ethylene and have a 70.degree. C. compression set of less
than 80 percent; less than 70 percent in other embodiments; less
than 60 percent in other embodiments; and, less than 50 percent,
less than 40 percent, and down to a compression set of 0 percent in
yet other embodiments.
[0066] In some embodiments, the multi-block copolymers may possess
a PDI fitting a Schultz-Flory distribution rather than a Poisson
distribution. The copolymers may be further characterized as having
both a polydisperse block distribution and a polydisperse
distribution of block sizes and possessing a most probable
distribution of block lengths. Preferred multi-block copolymers are
those containing 4 or more blocks or segments including terminal
blocks. More preferably, the copolymers include at least 5, 10 or
20 blocks or segments including terminal blocks.
[0067] In addition, the block interpolymers may have additional
characteristics or properties. In one aspect, the interpolymers,
preferably comprising ethylene and one or more co-polymerizable
comonomers in polymerized form, are characterized by multiple
blocks or segments of two or more polymerized monomer units
differing in chemical or physical properties (blocked
interpolymer), most preferably a multi-block copolymer, the block
interpolymer having a molecular fraction which elutes between
40.degree. C. and 130.degree. C. when fractionated using TREF,
characterized in that the fraction has a molar comonomer content
higher, at least 5 percent higher in some embodiments, at least 10
percent higher in other embodiments, than that of a comparable
random ethylene interpolymer fraction eluting between the same
temperatures, wherein the comparable random ethylene interpolymer
comprises the same comonomer(s), and has a melt index, density, and
molar comonomer content (based on the whole polymer) within 10
percent of that of the blocked interpolymer. The Mw/Mn of the
comparable interpolymer may also be within 10 percent of that of
the blocked interpolymer and/or, the comparable interpolymer may
have total comonomer content within 10 weight percent of that of
the blocked interpolymer.
[0068] Comonomer content may be measured using any suitable
technique, with techniques based on nuclear magnetic resonance
("NMR") spectroscopy preferred. Moreover, for polymers or blends of
polymers having relatively broad TREF curves, the polymer is first
fractionated using TREF into fractions each having an eluted
temperature range of 10.degree. C. or less. That is, each eluted
fraction has a collection temperature window of 10.degree. C. or
less. Using this technique, the block interpolymers have at least
one such fraction having a higher molar comonomer content than a
corresponding fraction of the comparable interpolymer.
[0069] Comonomer content may be measured using any suitable
technique, with techniques based on nuclear magnetic resonance
(NMR) spectroscopy preferred. Using this technique, the blocked
interpolymers have higher molar comonomer content than a
corresponding comparable interpolymer.
[0070] In some embodiments, for interpolymers of ethylene and
1-octene, the block interpolymer may have a comonomer content of
the TREF fraction eluting between 40 and 130.degree. C. greater
than or equal to the quantity (-0.2013)*T+20.07, where T is the
numerical value of the peak elution temperature of the TREF
fraction being compared, measured in .degree. C. The comonomer
content of the TREF fraction eluting between 40 and 130.degree. C.
may be greater than or equal to the quantity (-0.2013)*T+21.07 in
other embodiments
[0071] The interpolymers having the higher crystallinities may
especially have higher weight average molecular weights, M.sub.w
for example, ranging from a lower limit of 15,000 g/mole, 30,000
g/mole, preferably 50,000 g/mole to an upper limit of about
5,000,000 g/mole, preferably to about 2,500,000, and especially to
about 1,000,000 in some embodiments; from 1000 g/mole to 1,000,000
g/mole in other embodiments; from 10,000 g/mole to 500,000 g/mole
in other embodiments; and from 10,000 g/mole to 300,000 g/mole in
yet other embodiments. For example, polyolefin polymers having a
crystallinity of about 55% and higher with a M.sub.w from about
15,000 to about 1,000,000 g/mole are especially preferred. In
certain embodiments, when using higher crystallinity polyolefins,
the density of the ethylene/.alpha.-olefin polymers may range from
0.915 g/cm.sup.3 to 0.99 g/cm.sup.3 or 0.925 g/cm.sup.3 to 0.97
g/cm.sup.3.
[0072] The process of making the polymers has been disclosed in the
following patent applications: U.S. Provisional Application No.
60/553,906, filed Mar. 17, 2004; U.S. Provisional Application No,
60/662,937, filed Mar. 17, 2005; U.S. Provisional Application No.
60/662,939, filed Mar. 17, 2005; U.S. Provisional Application No.
60/662,938, filed Mar. 17, 2005; PCT Publication No. WO2005/90425,
filed Mar. 17, 2005; PCT Publication No. WO2005/90427, filed Mar.
17, 2005; and PCT Application No. PCT/US2005/008917, filed Mar. 17,
2005, all of which are incorporated by reference herein in their
entirety.
[0073] Dispersing Agent
[0074] Embodiments of the present invention use a dispersing agent
(or stabilizing agent) to promote the formation of a stable
dispersion or emulsion. In selected embodiments, the stabilizing
agent may be a surfactant, a polymer (different from the base
polymer detailed above), or mixtures thereof. In certain
embodiments, the polymer may be a polar polymer, having a polar
group as either a comonomer or grafted monomer. In preferred
embodiments, the stabilizing agent comprises one or more polar
polyolefins, having a polar group as either a comonomer or grafted
monomer. For example, the dispersing agent may include an
ethylene/alpha-beta unsaturated carboxylic acid copolymer. In some
embodiments, the ethylene/alpha-beta unsaturated carboxylic acid
copolymer may include an ethylene-acid copolymer, such as an
ethylene-acrylic acid copolymer or an ethylene methacrylic acid
copolymer.
[0075] Typical polymers include ethylene-acrylic acid (EAA) and
ethylene-methacrylic acid copolymers, such as those available under
the trademarks PRIMACOR.TM. (trademark of The Dow Chemical
Company), NUCREL.TM. (trademark of E.I. DuPont de Nemours), and
ESCOR.TM. (trademark of ExxonMobil) and described in U.S. Pat. Nos.
4,599,392, 4,988,781, and 5,938,437, each of which is incorporated
herein by reference in its entirety. Other polymers include
ethylene ethyl acrylate (EEA) copolymer, ethylene methyl
methacrylate (EMMA), and ethylene butyl acrylate (EBA). Other
ethylene-carboxylic acid copolymer may also be used. Those having
ordinary skill in the art will recognize that a number of other
useful polymers may also be used.
[0076] Other surfactants that may be used include long chain fatty
acids or fatty acid salts having from 12 to 60 carbon atoms. In
other embodiments, the long chain fatty acid or fatty acid salt may
have from 12 to 40 carbon atoms.
[0077] If the polar group of the polymer is acidic or basic in
nature, the stabilizing polymer may be partially or fully
neutralized with a neutralizing agent to form the corresponding
salt. In certain embodiments, neutralization of the stabilizing
agent, such as a long chain fatty acid or EAA, may be from 25% to
200% on a molar basis; from 50% to 110% on a molar basis in other
embodiments. For example, for EAA, the neutralizing agent is a
base, such as ammonium hydroxide or potassium hydroxide, for
example. Other neutralizing agents may include lithium hydroxide or
sodium hydroxide, for example. Those having ordinary skill in the
art will appreciate that the selection of an appropriate
neutralizing agent depends on the specific composition formulated,
and that such a choice is within the knowledge of those of ordinary
skill in the art.
[0078] Additional surfactants that may be useful in the practice of
the present invention include cationic surfactants, anionic
surfactants, zwitterionic, or non-ionic surfactants. Examples of
anionic surfactants include sulfonates, carboxylates, and
phosphates. Examples of cationic surfactants include quaternary
amines. Examples of non-ionic surfactants include block copolymers
containing ethylene oxide and silicone surfactants. Surfactants
useful in the practice of the present invention may be either
external surfactants or internal surfactants. External surfactants
are surfactants that do not become chemically reacted into the
polymer during dispersion preparation. Examples of external
surfactants useful herein include salts of dodecyl benzene sulfonic
acid and lauryl sulfonic acid salt. Internal surfactants are
surfactants that do become chemically reacted into the polymer
during dispersion preparation. An example of an internal surfactant
useful herein includes. 2,2-dimethylol propionic acid and its
salts.
[0079] In particular embodiments, the dispersing agent or
stabilizing agent may be used in an amount ranging from greater
than zero to about 60% by weight based on the amount of base
polymer (or base polymer mixture) used. For example, long chain
fatty acids or salts thereof may be used in an amount ranging from
0.5% to 10% by weight based on the amount of base polymer. In other
embodiments, ethylene-acrylic acid or ethylene-methacrylic acid
copolymers may be used in an amount from 0.5% to 60% by weight
based on polymer. In yet other embodiments, sulfonic acid salts may
be used in an amount from 0.5% to 10% by weight based on the amount
of base polymer.
[0080] The type and amount of stabilizing agent used may also
affect end properties of the cellulose-based article formed
incorporating the dispersion. For example, articles having improved
oil and grease resistance might incorporate a surfactant package
having ethylene-acrylic acid copolymers or ethylene-methacrylic
acid copolymers in an amount from about 10% to about 50% by weight
based on the total amount of base polymer. A similar surfactant
package may be used when improved strength or softness is a desired
end property. As another example, articles having improved water or
moisture resistance might incorporate a surfactant package
utilizing long chain fatty acids in an amount from 0.5% to 5%, or
ethylene-acrylic acid copolymers in an amount from 10% to 50%, both
by weight based on the total amount of base polymer. In other
embodiments, the minimum amount of surfactant or stabilizing agent
must be at least 1% by weight based on the total amount of base
polymer.
[0081] Additives
[0082] Additives may be used with the base polymer, dispersing
agent, or filler used in the dispersion without deviating from the
scope of the present invention. For example, additives may include
a wetting agent, surfactants, anti-static agents, antifoam agent,
anti block, wax-dispersion pigments, a neutralizing agent, a
thickener, a compatibilizer, a brightener, a rheology modifier, a
biocide, a fungicide, a shear stabilizer, a UV stabilizer, a
coefficient of friction modifier, and other additives known to
those skilled in the art.
[0083] For example, a formulation of the present invention may
include surfactants, frothing agents, dispersants, thickeners, fire
retardants, pigments, antistatic agents, reinforcing fibers,
antifoam agent, anti block, wax-dispersion, antioxidants, a
neutralizing agent, a rheology modifier, preservatives, biocides,
acid scavengers, a wetting agent, and the like. While optional for
purposes of the present invention, other components may be highly
advantageous for product stability during and after the
manufacturing process.
[0084] In addition, embodiments of the present invention optionally
include a filler wetting agent. A filler wetting agent generally
may help make the filler and the polyolefin dispersion more
compatible. Useful wetting agents include phosphate salts, such as
sodium hexametaphosphate. A filler wetting agent may be included in
a composition of the present invention at a concentration of at
least about 0.5 parts per 100 parts of filler, by weight.
[0085] Furthermore, embodiments of the present invention may
optionally include a thickener. Thickeners may be useful in the
present invention to increase the viscosity of low viscosity
dispersions. Thickeners suitable for use in the practice of the
present invention may be any known in the art such as for instance
poly-acrylate type or associate non ionic thickeners such, as
modified cellulose ethers. For example, suitable thickeners include
ALCOGUMT.TM. VEP-II (trademark of Alco Chemical Corporation),
RHEOVIS.TM. and VISCALEX.TM. (trademarks of Ciba Geigy), UCAR.RTM.
Thickener 146, or ETHOCEL.TM. or METHOCEL.TM. (trademarks of the
The Dow Chemical Company) and PARAGUM.TM. 241 (trademarks of
Para-Chem Southern, Inc.), or BERMACOL.TM. (trademark of Akzo
Nobel) or AQUALON.TM. (trademark of Hercules) or ACUSOL.RTM.
(trademark of Rohm and Haas). Thickeners may be used in any amount
necessary to prepare a dispersion of desired viscosity.
[0086] The ultimate viscosity of the dispersion is, therefore,
controllable. Addition of the thickener to the dispersion including
the amount of filler may be done with conventional means to result
in viscosities as needed. Viscosities of thus dispersions may reach
+3000 cP (Brookfield spindle 4 with 20 rpm) with moderate thickener
dosing (up to 4% preferably, below 3% based on 100 phr of polymer
dispersion). The starting polymer dispersion as described has an
initial viscosity prior to formulation with fillers and additives
between 20 cP and 1000 cP (Brookfield viscosity measured at room
temperature with spindle RV3 at 50 rpm). Still more preferably, the
starting viscosity of the dispersion may be between about 100 to
about 600 cP.
[0087] Also, embodiments of the present invention are characterized
by their stability when a filler is added to the
polymer/stabilizing agent. In this context, stability refers to the
stability of viscosity of the resultant aqueous polyolefin
dispersion. In order to test the stability, the viscosity is
measured over a period of time. Preferably, viscosity measured at
20.degree. C. should remain.+-.10% of the original viscosity over a
period of 24 hours, when stored at ambient temperature.
[0088] Fillers
[0089] Embodiments of the dispersions disclosed herein may include
a filler as part of the composition. A suitable filler loading in a
polyolefin dispersion may be from about 0 parts to about 600 parts
of filler per hundred parts of polyolefin. In certain embodiments,
the filler loading in the dispersion may be from about 0 parts to
about 200 parts of filler per hundred parts of a combined amount of
the polyolefin and the dispersing agent.
[0090] The filler material may include conventional fillers such as
milled glass, calcium carbonate, aluminum trihydrate, talc,
antimony trioxide, fly ash, clays (such as bentonite or kaolin
clays for example), titanium dioxide, zeolites, powdered metals,
organic or inorganic fibers, including carbon fibers, silicon
nitride fibers, steel wire or mesh, and nylon or polyester cording,
nano-sized particles, tackifiers, oil extenders, including
paraffinic or napthelenic oils, other known fillers.
[0091] Those having ordinary skill in the art will recognize that
the above list is a non-comprehensive listing of suitable polymers.
It will be appreciated that the scope of the present invention is
restricted by the claims only.
[0092] Dispersion Formulations
[0093] Dispersions formed in accordance with embodiments disclosed
herein may include a base polymer, which comprises a higher
crystallinity polyolefin, and a dispersing agent, which may
comprise at least one polar polyolefin. In preferred embodiments,
when using an EAA as the dispersing agent, the polymer-to-EAA ratio
is preferably between 50:50 to 90:10, and when using fatty acid
surfactants as the dispersing agent, the polymer-to-fatty-acid
ratio is preferably between 97:3 to 94:6.
[0094] With respect to the higher crystallinity polyolefin and the
dispersing agent, in some embodiments, the higher crystallinity
polyolefin may comprise between about 30 percent to about 99
percent by weight of the total amount of base polymer and
dispersing agent in the composition. In other embodiments, the
higher crystallinity polyolefin may comprise between about 50
percent and about 90 percent of the total amount of base polymer
and dispersing agent in the composition. In yet other embodiments,
the higher crystallinity polyolefin may comprise between about 60
percent and about 80 percent of the total amount of base polymer
and dispersing agent in the composition.
[0095] The higher crystallinity polyolefin may be contained within
the aqueous dispersion in an amount from about 1 percent by weight
to about 96 percent by weight. In some embodiments, the higher
crystallinity polyolefin may be present in the aqueous dispersion
in an amount from about 10 percent by weight to about 80 percent by
weight. In other embodiments, the higher crystallinity polyolefin
may be present in an amount from about 20 percent to about 70
percent by weight; and from about 30 percent to about 60 weight
percent by weight in yet other embodiments.
[0096] Dispersions formed in accordance with embodiments disclosed
herein may include a base polymer, which may include a higher
crystallinity polyolefin, a secondary polymeric component, which
may include at least one lower crystallinity polyolefin, and a
dispersing agent. The higher crystallinity polyolefin, in some
embodiments, may comprise from about 30 percent to 95 percent by
weight of the total amount of base polymer, secondary polymer, and
dispersing agent in the composition. In other embodiments, the
higher crystallinity polyolefin may comprise between about 50
percent and about 80 percent by weight; and, between about 60
percent to about 70 percent by weight in yet other embodiments. In
some embodiments, the secondary polymeric component may comprise
from 1 percent to 48 percent by weight of the total amount of base
polymer, secondary polymer, and dispersing agent in the
composition. In other embodiments, the secondary polymeric
component may comprise from 5 to 30 percent by weight; and from 10
percent to 25 percent by weight in yet other embodiments.
[0097] Benefits derived from a higher crystallinity polyolefin
dispersion may also be realized where the higher crystallinity
polyolefin is used as a minority component in a dispersion.
Accordingly, dispersions formed in accordance with other
embodiments disclosed herein may include a base polymer, which may
include a lower crystallinity polyolefin, a secondary polymeric
component, which may include a higher crystallinity polyolefin, and
a dispersing agent. The base polymer, in some embodiments, may
comprise from about 30 percent to 0.95 percent by weight of the
total amount of base polymer, higher crystallinity polyolefin, and
dispersing agent in the composition. In other embodiments, the base
polymer may comprise between about 50 percent and about 80 percent
by weight; and, between about 60 percent to about 70 percent by
weight in yet other embodiments. In other embodiments, the higher
crystallinity polyolefin component may comprise from 1 percent to
48 percent by weight of the total amount of base polymer, higher
crystallinity polyolefin, and dispersing agent in the composition.
In other embodiments, the higher crystallinity polyolefin component
may comprise from 5 percent to 30 percent by weight; and from 10
percent to 25 percent by weight in yet other embodiments.
[0098] With respect to the filler, typically, an amount greater
than about 0 parts to about 1000 parts per hundred of the polymer
(polymer meaning here the higher crystallinity polyolefin combined
with the secondary polymer (if any) and the dispersing agent) is
used. In selected embodiments, between about 50 parts to about 250
parts per hundred parts polymer are used. In other selected
embodiments, between about 10 parts to about 500 parts per hundred
parts polymer are used. In still other embodiments, from between
about 20 parts to 400 parts per hundred parts polymer are used. In
other embodiments, from about 0 parts to about 200 parts per
hundred are used.
[0099] The solid materials (higher crystallinity polyolefin plus
secondary polymer (if any) plus dispersing agent) are preferably
dispersed in water. In preferred embodiments, sufficient
neutralizing agent is added to neutralize the resultant dispersion
to achieve a pH range of between about 4 to about 14. In preferred
embodiments, sufficient base is added to maintain a pH of between
about 6 to about 11; in other embodiments, the pH may be between
about 8 to about 10.5. Water content of the dispersion is
preferably controlled so that the solids content is between about
1% to about 74% by volume. In another embodiment, the solid content
is between about 25% to about 74% by volume. In particular
embodiments, the solids range may be between about 10% to about 70%
by weight. In other particular embodiments, the solids range is
between about 20% to about 60% by weight. In particularly preferred
embodiments, the solids range is between about 30% to about 55% by
weight.
[0100] Dispersions formed in accordance with embodiments of the
present invention are characterized in having an average particle
size from about 0.1 micron to about 5.0 micron. In other
embodiments, dispersions have an average particle size from about
0.5 .mu.m to about 2.7 .mu.m. In other embodiments, from about 0.8
.mu.m to about 1.2 .mu.m. By "average particle size", the present
invention means the volume-mean particle size. In order to measure
the particle size, laser-diffraction techniques may be employed for
example. A particle size in this description refers to the diameter
of the polymer in the dispersion. For polymer particles that are
not spherical, the diameter of the particle is the average of the
long and short axes of the particle. Particle sizes may be measured
on a Beckman-Coulter LS230 laser-diffraction particle size analyzer
or other suitable devices, such as the DOWM 102 E06A.
[0101] The coatings obtained from dispersions formed in accordance
with this disclosure exhibit excellent moisture resistance, water
repellency, oil and grease resistance, thermal adhesion to paper
and other natural and synthetic substrates such as metal, wood,
glass, synthetic fibers and films, and woven and non-woven
fabrics.
[0102] The aqueous dispersions disclosed herein may be used as
coatings, froths, as articles such as foams, and adhesives for
bonding and sealing various substrates, especially corrugated boxes
and plastics films such as BOPP, polyester and polyamide films.
Aqueous dispersion of the present invention may be used for such
applications as a binder of a coating or ink composition for a
coated paper, paper-board, wall-paper, or other cellulose based
article. The aqueous dispersion may be coated by various
techniques, for example, by spray coating, curtain coating, coating
with a roll coater or a gravure coater, brush coating, or dipping.
The coating is preferably dried by heating the coated substrate to
70.degree. C. to 150.degree. C. for 1 sec to 300 sec.
[0103] Examples of aqueous dispersions that may be incorporated
into the additive composition of the present disclosure are
disclosed, for instance, in U.S. Patent Application Publication No.
2005/0100754, U.S. Patent Application Publication No. 2005/0192365,
PCT Publication No. WO 2005/021638, and PCT Publication No. WO
2005/021622, which are all incorporated herein by reference.
[0104] Some embodiments of the foams formed from the aqueous
dispersion disclosed herein may have a compression set value, as
defined below, at testing conditions of 80.degree. C., 20 minutes,
and 0.5 psig (4.4 kPag), of less than 80 percent. In other
embodiments, the foams may have a compression set of less than 70
percent; less than 65 percent in other embodiments; and less than
60 percent in yet other embodiments.
[0105] Some embodiments of the foams formed from the aqueous
dispersion disclosed herein may have a compression set value, as
defined below, at testing conditions of 80.degree. C., 20 minutes,
and 0.25 psig (1.7 kPag), of less than 70 percent. In other
embodiments, the foams may have a compression set of less than 60
percent; less than 55 percent in other embodiments; and less than
50 percent in yet other embodiments.
[0106] Some embodiments of the foams formed from the aqueous
dispersion disclosed herein may have a compression set value, as
defined below, at testing conditions of 80.degree. C., 20 minutes,
and 0.1 psig (0.69 kPag), of less than 60 percent. In other
embodiments, the foams may have a compression set of less than 50
percent; less than 45 percent in other embodiments; and less than
40 percent in yet other embodiments.
[0107] Forming the Dispersion
[0108] The dispersions of the present invention may be formed by
any number of methods recognized by those having skill in the art.
In selected embodiments, the dispersions may be formed by using
techniques, for example, in accordance with the procedures as
described in WO2005/021638, which is incorporated by reference in
its entirety.
[0109] In a specific embodiment, a higher crystallinity polyolefin
and a dispersing agent may be melt-kneaded along with water and a
neutralizing agent to form a dispersion. Those having ordinary
skill in the art will recognize that a number of other neutralizing
agents may be used. In some embodiments, the filler may be added
after blending the base polymer and dispersing agent. In some
embodiments, the dispersion is first diluted to contain about 1% to
about 3% by weight water and then, subsequently, further diluted to
comprise greater than about 25% by weight water.
[0110] Any melt-kneading means known in the art may be used. In
some embodiments, a kneader, a BANBURY.TM. mixer, single-screw
extruder or a multi-screw extruder is used. A process for producing
the dispersions in accordance with the present invention is not
particularly limited. One preferred process, for example, is a
process comprising melt-kneading the above-mentioned components
according to U.S. Pat. No. 5,756,659 and U.S. Pat. No.
6,455,636.
[0111] Referring now to FIG. 1, a schematic diagram of an extrusion
apparatus for manufacturing polymer dispersions is illustrated. An
extruder 1, such as a twin screw extruder, may be coupled to a
pressure control device 2, such as, but not limited a pressure
control valve, a back pressure regulator, a melt pinup, a gear
pump, and the like. Neutralizing agent reservoir 3 and an initial
water reservoir 4, each of which includes a pump (not shown), may
also be provided. Desired amounts of neutralizing agent and initial
water are provided from the neutralizing agent reservoir 3 and the
initial water reservoir 4, respectively. Any suitable pump may be
used, but in some embodiments a pump that provides the desired flow
at a pressure of 3480 psig (240 bar, 24 MPag) is used to provide
the neutralizing agent and the initial water to the extruder 20. In
other embodiments, a liquid injection pump provides the required
flow at 2900 psig (200 bar, 20 MPag) or at 1930 psig (133 bar, 13.3
MPag). In some embodiments, the neutralizing agent and initial
water are preheated in a preheater.
[0112] Polymer resin(s), in the form of pellets, powder, or flakes,
for example, may be fed from the feeder 7 to an inlet 8 of the
extruder 1, where the resin is melted or compounded. The dispersing
agent is typically added to the extruder through and along with the
resin but may be provided separately to the twin screw extruder 1.
The resin melt is then delivered from the mix and convey zone to an
emulsification zone of the extruder where the initial amount of
water and neutralizing agent from the reservoirs 3 and 4 is added
through inlet 5. The emulsified mixture may be further diluted with
additional water via inlet 9 from reservoir 6 in a dilution and
cooling zone of the extruder 1. Typically, the dispersion is
diluted to at least 30 weight percent water in the cooling
zone.
[0113] In some embodiments, dispersing agent may be added
additionally or exclusively to the water stream. In some
embodiments, the emulsified mixture is further diluted with
additional water inlet 9 from reservoir 6 in a dilution and cooling
zone of the extruder 1. Typically, the dispersion is diluted to at
least 30 weight percent water in the cooling zone. In addition, the
diluted mixture may be diluted any number of times until the
desired dilution level is achieved. In some embodiments, water is
not added into the twin screw extruder 1 but rather to a stream
containing the resin melt after the melt has exited from the
extruder
[0114] Referring now to FIG. 2, a schematic diagram of an extrusion
system used in embodiments disclosed herein is illustrated. An
extruder 30, such as a twin screw extruder, may be coupled to a
control valve 32, for controlling extruder discharge pressure. In
some embodiment, control valve 32 may be a V-ball control valve. In
other embodiments, control valve 32 may be a micro-notch V-ball
control valve.
[0115] Neutralizing agent reservoir 34 and an initial dispersion
medium reservoir 36, each of which includes a pump (not shown), may
also be provided. Desired amounts of neutralizing agent and initial
dispersion medium are provided from the neutralizing agent
reservoir 34 and the initial water reservoir 36, respectively.
[0116] Polymer resin(s), in the form of pellets, powder, or flakes,
for example, may be fed from the feeder 37 to an inlet 38 of the
extruder 30. The dispersing agent is typically added to the
extruder through and along with the resin but may be provided
separately to the twin screw extruder 30. The polymer and
dispersing agent are then melted, mixed, and conveyed by screws 40
in mix and convey zone 42.
[0117] The resin melt is then delivered from the mix and convey
zone to a high internal phase emulsion creation zone 43 (referred
to herein as the "HIPE zone") of the extruder. In the HIPE zone, an
initial amount of dispersion medium and neutralizing agent from the
reservoirs 34 and 36 is added through inlet 44.
[0118] In the HIPE zone 43, the dispersion particle size is formed,
based upon the interfacial chemistry of the mixture components, the
mass transfer of the neutralizing agent, and the distributive and
dispersive mixing imparted by the screws 40, including the stress,
strain and passage frequency.
[0119] The emulsified mixture may be further diluted with
additional dispersion medium via one or more of inlet 46, 47, 48
from reservoir 50 in dilution zone 52 of the extruder 30.
Typically, the dispersion is diluted to at least 30 weight percent
dispersion medium in dilution zone 52. In dilution zone 52, the
packing fraction of the dispersion particles and the viscosity of
the mixture are reduced. For example, the viscosity may be reduced
from a magnitude of about 10.sup.6 to about 10.sup.2
centipoise.
[0120] A cooling zone 54 may be located toward the end of screw 40,
near the outlet of extruder 30. Cooling zone 54, providing heat
exchange between the dispersion mixture and a cooling medium, not
shown, may be used to cool the dispersion mixture to a temperature
below that of the boiling point of the dispersion medium. For
example, where the dispersion medium is water, the dispersion
mixture may be cooled to a temperature below about 100.degree. C.
The reduction in dispersion mixture temperature may allow further
processing of the mixture without unwanted loss of dispersion
medium through evaporation.
[0121] The cooled dispersion may then exit extruder 30 via outlet
56. Outlet 56 may be coupled to control valve 32, as described
above, to maintain extruder discharge pressure control.
[0122] Regarding screws 40 and the internals of extruder 30, one or
more rotating restriction orifices 58 may be located along screw 40
in some embodiments. In addition to control valve 32, rotating
restriction orifices 58 may improve stability of the dispersion
forming process. In other embodiments, non-rotating restriction
orifices, not shown, may be used.
[0123] Screws 40 may also include high-mixing kneading disks 60 in
some embodiments. In addition to the high-mixing kneading disks 60
described above, embodiments of the extrusion apparatus disclosed
herein may also include low free volume kneading disks 62, which
may minimize the volume weighted particle size distribution of
dispersions formed using extruder 30.
[0124] In other embodiments of the extrusion apparatus, the reverse
elements may be removed, preventing unwanted back mixing.
Additionally, the melt seal may be located directly upstream of the
HIPE zone in some embodiments.
[0125] As illustrated in FIG. 2, HIPE zone 43 may be variable in
length. Depending upon the feed composition (such as the polymer,
dispersing agent, neutralizing agent, etc.), it may be desirable to
have a longer or a shorter HIPE zone. Multiple dispersion medium
injection points 46, 47, 48 may be provided to allow the HIPE zone
to be extended or shortened as needed. As the particle size of the
dispersed polymer particles is formed in the HIPE zone, adequate
mixing should be provided to develop the desired particle size.
Having a variable length for the HIPE zone may allow for a broader
range of polymers to be processed in a single extruder, providing
for process flexibility, among other benefits.
[0126] For example, the twin screw extruder barrels, screws, and
dilution medium injection points may such that the length to
diameter (L/D) of the HIPE zone is at least 20 when producing fatty
acid dispersions and that the L/D of the HIPE zone is at least 16
when producing EEA dispersions. Additionally, the twin screw
extruder barrels, screws, and dilution medium injection points may
such that the 1st dilution zone L/D is at least 4 when producing
fatty acid dispersions and that the 1st dilution zone L/D is at
least 8 when producing EEA dispersions.
[0127] The apparatuses described above may be used to produce
dispersions, where, in some embodiments, the polymer feed rate may
range from about 50 to about 2000 lb/h (about 22 to about 907
kg/h). In other embodiments, the polymer feed rate may range from
about 100 to about 1000 lb/h (between about 45 and about 454
kg/h).
[0128] In other embodiments, the screw speed may range from about
300 rpm to about 1200 rpm. In yet other embodiments, the extruder
discharge pressure may be maintained at a pressure ranging from
about 300 to about 800 psig (from about 21 bar to about 56
bar).
[0129] The above described extrusion apparatus may be used to form
polymer dispersions. The polymer dispersions may be formed from any
thermoplastic polymer in some embodiments, polyolefins in other
embodiments, and ethylene-based polymers or propylene-based
polymers in other embodiments. In select embodiments, the extrusion
apparatus may be useful for forming aqueous dispersions of
polyolefins, including ethylene-based and propylene-based polymers,
copolymers, interpolymers, and multi-block interpolymers.
[0130] Polyolefin dispersions, in particular, when applied to a
substrate, may provide for water and chemical resistance, heat
sealability, adhesion to polyolefin substrates, low temperature
flexibility. Additionally, the wide range of polyolefins may
provide raw materials for producing dispersions and coatings having
a wide range of hardness and heat resistance. Also, most
polyolefins are compliant with various regulations allowing for
direct food contact.
[0131] The process for forming polyolefin dispersions described
above may be integrated with various downstream processes, such as
foaming and spray drying, to create foams, films, coatings,
powders, and other value added products. Additionally, the
dispersions may provide some synergy with other polyolefin system
components, such as fibers and films.
[0132] In particular embodiments, it may be desired to utilize the
dispersion in the form of foam. When preparing foams, it is often
preferred to froth the dispersion. For example, froths and foams
may be prepared as described in WO2005/021622, which is fully
incorporated herein by reference. Preferred in the practice of this
invention is the use of a gas as a frothing agent. Examples of
suitable frothing agents include: gases and/or mixtures of gases
such as, air, carbon dioxide, nitrogen, argon, helium, and the
like. Particularly preferable is the use of air as a frothing
agent. Frothing agents are typically introduced by mechanical
introduction of a gas into a liquid to form a froth. This technique
is known as mechanical frothing. In preparing a frothed dispersion,
it is preferred to mix all components and then blend the air or gas
into the mixture, using equipment such as an OAKES, MONDO, or
FIRESTONE frother.
[0133] Surfactants useful for preparing a stable froth are referred
to herein as foam stabilizers. Foam stabilizers are useful in the
practice of the present invention. Those having ordinary skill in
this field will recognize that a number of foam stabilizers may be
used. Foam stabilizers may include, for example, sulfates,
succinamates, and sulfosuccinamates.
EXAMPLES
[0134] To test the dispersibility of higher crystallinity
polyolefins, a number of dispersions are formulated, and their
performance measured. As an initial test, seven dispersions, using
EAA as the stabilizing agent are formed. Specifically, 70/30
polymer/stabilizing agent blends are formed, using thermoplastic
ethylene/acrylic acid copolymer with an acrylic acid content of
20.5 wt %, a density of about 0.958 g/cm.sup.3 (ASTM D-792) and a
melt index of 13.5 g/10 min. (as determined according to ASTM D1238
at 125.degree. C. and 2.16 kg) a Mw/Mn of about 3.7, and a melting
point of about 77.degree. C. (as determined by DSC at a scanning
rate of about 10.degree. C. per minute), commercially available as
PRIMACOR. 5980I (available from The Dow Chemical Company, Midland,
Mich.), as the stabilizing agent.
[0135] As base polymers, AFFINITY EG8150G (density of 0.868 g/cc,
MI of 0.5 g/10 min.), AFFINITY EG8100G (density of 0.870 g/cc, MI
of 1 g/10 min.), AFFINITY PL 1280G (density of 0.900 g/cc, MI of
6.00), DOWLEX 2035 (density of 0.919 g/cc, MI of 6 g/10 min),
DOWLEX 2027G (density of 0.941 g/cc, MI of 4 g/10 min.),
ethylene/1-hexene copolymer DMDA-8907 (density of 0.952 g/cc, MI of
6.8 g/10 min.), and ethylene/homopolymer DMDA-8007 (density of
0.965 g/cc, MI of 83 g/10 min), all commercially available from
Union Carbide Corp. and/or The Dow Chemical Company, Midland,
Mich., are used.
[0136] The conditions for making the seven formulations are listed
in Table 1 below.
TABLE-US-00001 TABLE 1 Formulation 1 2 3 4 5 6 7 Base Polymer
AFFINITY AFFINITY AFFINITY DOWLEX DOWLEX DMDA-8907 DMDA-8007
EG8150G EG8100G PL1280G 2035 2027G Stabilizing PRIMACOR PRIMACOR
PRIMACOR PRIMACOR PRIMACOR PRIMACOR PRIMACOR Agent 5980I 5980I
5980I 5980I 5980I 5980I 5980I Neutralizing KOH @30% KOH @30% KOH
@30% KOH @30% KOH @30% KOH @30% KOH @30% Agent & w/v w/v w/v
w/v w/v w/v w/v Concentration 500 #/Hr 280 280 280 280 280 280 280
Feeder Rate lb/hr 200 #/Hr 120 120 120 120 120 120 120 Feeder Rate
lb/hr Base Pump 67 66 67 66 67 67 67 lb/hr 1A Water lb/hr 67 67 67
67 67 68 67 1.sup.st Dilution 305 304 304 302 305 307 306 lb/hr
2.sup.nd Dilution 145 145 145 145 145 145 145 lb/hr Total Feed 985.
984 984 981 985 987 986 Rate lb/hr Weight & AA 20 20 20 20 20
20 20 in Polymer % MW of AA 72 72 72 72 72 72 72 g/gmole MW of Base
56 56 56 56 56 56 56 g/gmole Calc. HIPE 78 78 78 78 78 78 78.
solids content % w/w Calc. 1.sup.st dil. 42 42 42 42 42 42 42
solids content % w/w Calc. degree of 88 87 87 86 88 87 87
neutralization % ZSK motor 149 151 137 142 148 145 143 current,
amps ZSK motor 1180 1180 1180 1180 1180 1180 1180 speed, rpm ZSK
Ind. Disc 92 88 84 83 84 86 86. Temp .degree. C. Actual suction 397
405 410 424 394 385 410 pressure, psig Cooler 37 37 35 37 36 39 42
discharge temp .degree. C. Initial Water 117 117 117 117 117 117
117 Temp .degree. C. Initial Water 614 602 528 549 574 529 550
Pressure .degree. C. 1.sup.st Dilution 387 397 399 416 382 363 398
pressure, psig 1.sup.st Dilution 110 110 110 109 108 107 106 Temp
.degree. C.
[0137] The dispersion formulations noted above are manufactured
using an extrusion apparatus similar to that illustrated in FIG. 2.
The barrel/zone temperature control conditions for the seven
formulations are given in Table 2 below.
TABLE-US-00002 TABLE 2 Formulation 1 2 3 4 Barrel/Zone Setpoint
Actual Setpoint Actual Setpoint Actual Setpoint Actual Temp Control
.degree. C. Zone 1 22 21 20 20 Zone 2 100 91 100 89 100 89 100 90
Zone 3 150 152 150 151 150 153 150 151 Zone 4 150 167 150 164 150
152 150 153 Zone 5 180 205 180 196 180 180 180 185 Zone 6 200 199
200 202 200 204 200 205 Zone 7 200 201 200 197 200 191 200 197 Zone
8 150 166 150 163 150 153 150 154 Zone 9 70 132 70 129 70 125 70
127 Zone 10 70 116 70 114 70 110 70 111 Zone 11 70 83 70 82 70 78
70 80 Zone 12 70 73 70 72 70 71 70 71 Transition 70 69 70 76 70 75
70 69 Piece .degree. C. Diverter 100 99 100 101 100 110 100 101
Valve .degree. C. Formulation 5 6 7 Barrel/Zone Temp Control
Setpoint Actual Setpoint Actual Setpoint Actual .degree. C. Zone 1
19 19 20 Zone 2 100 87 100 88 100 98 Zone 3 150 150 150 149 150 150
Zone 4 150 161 150 157 150 152 Zone 5 180 179 180 184 180 176 Zone
6 200 203 200 205 200 204 Zone 7 200 203 200 195 200 202 Zone 8 150
162 150 156 150 153 Zone 9 70 129 70 126 70 121 Zone 10 70 114 70
112 70 107 Zone 11 70 81 70 81 70 80 Zone 12 70 72 70 74 70 74
Transition Piece .degree. C. 70 76 70 69 70 77 Diverter Valve
.degree. C. 100 109 100 99 100 110
[0138] The end results of the seven formulations are shown in Table
3 below.
TABLE-US-00003 TABLE 3 Formulation 1 2 3 4 5 6 7 Base Polymer
AFFINITY AFFINITY AFFINITY DOWLEX DOWLEX DMDA- DMDA- EG8150G
EG8100G PL1280G 2035 2027G 8907 8007 Polymer 0.868 0.870 0.900
0.919 0.941 0.952 0.965 Density (g/cc) Polymer MI 0.50 1.00 6.00
6.00 4.00 6.80 8.30 dg/min Volume Mean 2.5 1.8 1.0 1.0 1.2 1.0 0.9
Particle Size (microns) Solids 47.2 46.6 41.9 41.4 41.4 41.4 41.5
Content % w/w Viscosity cP 157 179 135 116 104 112 120 pH 9.9 10.1
9.8 10.1 10.2 10.2 10.3 Yellowness 1.7 1.4 1.2 1.2 1.3 0.9 0.7
Index Filterable 0.0142 0.0046 0.0076 0.0028 0.0018 0.0020 0.0044
Residue % w/w
Example 8
[0139] To prepare the dispersion, 100 parts by weight of a high
density polyethylene homopolymer, available from The Dow Chemical
Company under the name HDPE 30460M, with a melt index of about 30
g/10 minutes as determined according to ASTM D-1238 at 190.degree.
C. and 2.16 kg and a DSC melting point of about 130.degree. C. (as
determined by DSC at a scanning rate of about 10.degree. C. per
minute) is melt kneaded at 145.degree. C. in a twin screw extruder
at a rate of 4.5 kg/hr along with 6.4 parts of a synthetic C26 mean
carboxylic acid available from Baker Petrolite under the tradename
of UNICID 350.
[0140] Upon the melt kneaded product above, 4.6 parts by weight of
an aqueous solution of 19 weight percent potassium hydroxide is
continuously fed into a downstream injection port at a rate of 0.2
kg/hr (at a rate of 4.1 weight percent of the total mixture). This
aqueous dispersion is subsequently diluted with additional water at
a rate of 17 kg/hr before exiting the extruder. This aqueous
dispersion having a solids content of 21.9 weight percent at pH
12.2 is obtained with a Brookfield viscosity of <75 cP (RV1
spindle, 22.degree. C., 20 rpm). The dispersed particle size as
measured with a Coulter LS230 light scattering instrument is 1.12
micron.
Example 9
[0141] To prepare the dispersion, 100 parts by weight of a random
polypropylene copolymer, available from The Dow Chemical Company
under the name DOW 6D43 Polypropylene Resin, with a melt flow rate
of about 35 g/10 minutes as determined according to ASTM D-1238 at
230.degree. C. and 2.16 kg and a DSC melting point of about
140.degree. C. (as determined by DSC at a scanning rate of about
10.degree. C. per minute) is melt kneaded at 165.degree. C. in a
twin screw extruder at a rate of 4.5 kg/hr along with 6.4 parts of
a synthetic C26 mean carboxylic acid available from Baker Petrolite
under the tradename of UNICID 350.
[0142] Upon the melt kneaded product above, 4.8 parts by weight of
an aqueous solution of 16 weight percent potassium hydroxide is
continuously fed into a downstream injection port at a rate of 0.2
kg/hr (at a rate of 4.3 weight percent of the total mixture). This
aqueous dispersion is subsequently diluted with additional water at
a rate of 7.2 kg/hr before exiting the extruder. This aqueous
dispersion having a solids content of 34.8 weight percent at pH
11.8 is obtained with a Brookfield viscosity of <75 cP (RV1
spindle, 22.degree. C., 20 rpm). The dispersed particle size as
measured with a Coulter LS230 light scattering instrument is 0.61
micron.
Example 10
[0143] To prepare the dispersion, 100 parts by weight of a random
polypropylene copolymer, available from The Dow Chemical Company
under the name DOW 6D43 Polypropylene Resin, with a melt flow rate
of about 35 g/10 minutes as determined according to ASTM D-1238 at
230.degree. C. and 2.16 kg and a DSC melting point of about
140.degree. C. (as determined by DSC at a scanning rate of about
10.degree. C. per minute) is melt kneaded at 175.degree. C. in a
twin screw extruder at a rate of 4.5 kg/hr along with 42.8 parts by
weight of a thermoplastic ethylene/acrylic acid copolymer with an
acrylic acid content of 20.5 wt %, a density of about 0.958
g/cm.sup.3 (ASTM D-792) and a melt index of 300 g/10 min. (as
determined according to ASTM D1238 at 190.degree. C. and 2.16 kg)
and a melting point of about 77.degree. C. (as determined by DSC at
a scanning rate of about 10.degree. C. per minute), commercially
available from The Dow Chemical Company.
[0144] Upon the melt kneaded product above, 38.1 parts by weight of
an aqueous solution of 14 weight percent potassium hydroxide is
continuously fed into a downstream injection port at a rate of 1.7
kg/hr (at a rate of 21.0 weight percent of the total mixture). This
aqueous dispersion is subsequently diluted with additional water at
a rate of 8.9 kg/hr before exiting the extruder. This aqueous
dispersion having a solids content of 39.4 weight percent at pH
11.1 is obtained with a Brookfield viscosity of 140 cP (RV1
spindle, 22.degree. C., 20 rpm). The dispersed particle size as
measured with a Coulter LS230 light scattering instrument is 0.97
micron.
[0145] Extruder Examples
[0146] Dispersions similar to those of Examples 1-7 above, are
produced using an extruder apparatus similar to that illustrated in
FIG. 2. The extruder apparatus includes a self-cleaning micro-notch
V-ball control valve, rotating restriction orifices, and the
above-described high-mixing kneading disks. For comparative
purposes, extruder operations are compared to an unmodified
extruder apparatus having a back pressure regulator at the exit of
the extruder for pressure control, similar to that illustrated in
FIG. 1. The two extruder apparatuses have similar L/D's for both
the emulsification zone or HIPE zone and the first dilution
zone.
[0147] Comparison of the extruder operations indicates that
operation of the modified extruder apparatus (FIG. 2) is much
improved compared to the unmodified extruder apparatus. Comparing
FIGS. 3a and 3b, the variance in extruder discharge pressure
(DISCHARGE), neutralizing agent addition pressure (IA-PSI), and
first dilution zone pressure (ISTDILPSI) are each decreased for the
modified extruder apparatus, indicative of improved process
stability.
[0148] The improved process stability achieved through use of one
or more of the V-ball control valve, the high-mixing kneading
disks, and the rotating restriction orifices may result in a more
consistent dispersion product. For example, the feed rate of
neutralizing agent may be more consistent, as illustrated in FIG.
4, due to the improved extruder pressure control obtained via one
or more of the noted modifications.
[0149] Higher crystallinity polyolefin foams formed from the
dispersion of higher crystallinity polyolefins may have a number of
useful properties. Modified foams are also within the purview of
this invention and may include micro-cavity containing
thermoplastic foams such as those disclosed in U.S. Provisional
Application Ser. No. 60/700,644. The micro-cavity containing
additives include such materials as super absorbent polymers (SAP)
for articles such as infant and children diapers, adult
incontinence pants, feminine hygiene pads, household cleaning
articles, pet urine absorption mats/pads, and garbage bag liquid
absorbent pads.
[0150] Advantageously, the present invention provides for aqueous
dispersions of higher crystallinity polyolefin. Coatings and
articles produced from dispersions disclosed herein may
advantageously have a higher heat resistance, a greater resistance
to compression set at elevated temperatures, and may exhibit a
broader operating window in various extrusion and molding
process.
[0151] These dispersions may be used as coatings and as articles
such as foams. Alternative uses for these dispersions include
adhesives for bonding and sealing various substrates, especially
corrugated boxes and plastics films such as biaxially oriented
polypropylene (BOPP), polyester and polyamide films. Additionally,
these foams may be used in the construction of diapers and feminine
hygiene pads as the liquid absorbent and distribution layer. Today,
such diapers and feminine hygiene pads are packaged tightly. Foams
formed from dispersions disclosed herein may provide significantly
lower compression set at 40.degree. C., allowing near full recovery
of the original foam thickness, a requirement for the end
product.
[0152] In another aspect, dispersions made using higher
crystallinity polyolefins may be used as a coating or adhesive
where heat resistance is required. Many automotive applications
require heat resistance at temperatures of 60.degree. C. and
higher.
[0153] In addition to the mechanical emulsification of a higher
crystallinity polyolefin dispersion, blends of different higher
crystallinity polyolefins and blends of higher crystallinity
polyolefins and other polyolefins and plastics may be produced to
enhance certain properties such as adhesion to specific substrates
such as paper or glass and heat resistance, improve the abrasion
resistance of polyolefin films, and allow the deposition of harder
materials on a substrate.
[0154] In another embodiment of the present invention, a dispersion
of higher crystallinity polyolefins may be used in connection with
other dispersions to form a blended dispersion product.
[0155] In addition to the applications described above, higher
crystallinity polyolefin dispersions described herein may be useful
in a number of other applications.
[0156] Accordingly, in one application, dispersions of higher
crystallinity polyolefins may be useful in cellulose-based
articles, especially having a specific volume of less than 3
cc/.mu.m, for example, paper and board structures, incorporating a
compound comprising an aqueous polyolefin dispersion resulting in
articles having improved properties. In various embodiments, the
articles may have improved oil and grease resistance, improved
water resistance, controlled coefficients of friction, thermal
embossability, thermal formability, improved wet and dry strength,
or an improved softness, among others. Such techniques and
compositions are disclosed in U.S. Application Ser. No. 60/750,466,
which is expressly incorporated by reference in its entirety.
[0157] Thus, in one application, dispersions of higher
crystallinity polyolefins may be useful in providing a
cellulose-based article having, especially those having a specific
volume of less than 3 cc/gm, including: a cellulose-based
composition; and an applied compound. The applied compound, at the
time of application, may include a higher crystallinity polyolefin
and at least one dispersing agent. The article may have an oil and
grease resistance value of at least 9 as measured using the Kit
test at an exposure time of 15 seconds.
[0158] Thus, in one application, dispersions of catalytic linear
multi-block olefins may be useful in providing a cellulose-based
article, especially those having a specific volume of less than 3
cc/gm, including: a cellulose-based composition; and an applied
compound. The applied compound, at the time of application, may
include a higher crystallinity polyolefin, and at least one
dispersing agent. The cellulose-based article may have a water
resistance value of less than about 10 g/m.sup.2/120 seconds as
measured via the Cobb test.
[0159] The Kit test: the kit value of samples may be determined
using TAPPI T559 cm-02. The test was performed flat as described in
the TAPPI test. This involves putting five separate drops of oil
onto the board's surface and inspecting the board after a specified
amount of exposure time (15 seconds) to see if any pronounced
darkening of the paper appears. A modified Kit test run at elevated
temperature(s) can be useful to distinguish deposited dispersions
made using the catalytic linear multi-block polymers, especially
for ethylene based block polymers versus other ethylene based
random copolymers. Such elevated temperatures for testing can be as
high as about 80.degree. C., but preferably tested around
50.degree. C. Film layers made using deposited dispersions from the
catalytic linear ethylenic multi-block polymers show higher Kit
values at 50.degree. C. than Kit values (also at 50.degree. C.) for
random ethylene polymer based deposited dispersions, even at
similar overall ethylene polymer density and melt index.
[0160] The Cobb test: Cobb tests may be performed in accordance
with ASTM D3285-93. The exposure time was 2 minutes. The test
involves a known volume of water (100 ml) being poured onto a
specific area of the board's surface (100 cm.sup.2). The board is
weighed before and after the exposure and the difference between
the two can then be expressed as the weight per unit area of water
absorbed in that given time; the lower the Cobb value, the better
the result. A modified Cobb test run at elevated temperature(s) can
be useful to distinguish deposited dispersions made using higher
crystallinity polyolefins. Such elevated temperatures for testing
can be as high as about 80.degree. C., but preferably tested around
50.degree. C.
[0161] Thus, embodiments disclosed herein may relate to
cellulose-based compositions, which are generally referred to as
"paper and/or paperboard products" (i.e., other than paper towels),
such as newsprint, uncoated groundwood, coated groundwood, coated
free sheet, uncoated free sheet, packaging and industrial papers,
linerboard, corrugating medium, recycled paperboard, bleached
paperboard, writing paper, typing paper, photo quality paper,
wallpaper, etc. Such compositions can generally be formed in
accordance with the present invention from at least one paper
web.
[0162] For example, in one embodiment, the paper product can
contain a single-layered paper web formed from a blend of fibers.
In another embodiment, the paper product can contain a
multi-layered paper (i.e., stratified) web. Furthermore, the paper
product can also be a single- or multi-ply product (e.g., more than
one paper web), wherein one or more of the plies may contain a
paper web formed according to the present invention. Normally, the
basis weight of a paper product of the present invention is between
about 10 grams per square meter (g/m.sup.2) to about 525 g/m.sup.2.
Normally, the specific volume of a paper product in accordance with
embodiments of the present invention is between about
0.3.degree.g/cc to about 2 g/cc.
[0163] Any of a variety of materials can be used to form the paper
products of the present invention. For example, the material used
to make paper products can include fibers formed by a variety of
pulping processes, such as kraft pulp, sulfite pulp,
thermomechanical pulp, etc.
[0164] Papermaking fibers useful in the process of the present
invention include any cellulosic fibers that are known to be useful
for making cellulosic base sheets. Suitable fibers include virgin
softwood and hardwood fibers along with non-woody fibers, as well
as secondary (i.e., recycled) papermaking fibers and mixtures
thereof in all proportions. Non-cellulosic synthetic fibers can
also be included in the aqueous suspension. Papermaking fibers may
be derived from wood using any known pulping process, including
kraft and sulfite chemical pulps.
[0165] Fibers suitable for making paper webs comprise any natural
or synthetic cellulosic fibers including, but not limited to
nonwoody fibers, such as cotton, abaca, kenaf, sabai grass, flax,
esparto grass, straw, jute hemp, bagasse, milkweed floss fibers,
and pineapple leaf fibers; and woody fibers such as those obtained
from deciduous and coniferous trees, including softwood fibers,
such as northern and southern softwood kraft fibers; hardwood
fibers, such as eucalyptus, maple, birch, and aspen. Woody fibers
can be prepared in high-yield or low-yield forms and can be pulped
in any known method, including kraft, sulfite, high-yield pulping
methods and other known pulping methods. Fibers prepared from
organosols pulping methods can also be used, including the fibers
and methods disclosed in U.S. Pat. No. 4,793,898, issued Dec. 27,
1988 to Laamanen et al.; U.S. Pat. No. 4,594,130, issued Jun. 10,
1986 to Chang et al.; and U.S. Pat. No. 3,585,104. Useful fibers
can also be produced by anthraquinone pulping, exemplified by U.S.
Pat. No. 5,595,628 issued Jan. 21, 1997, to Gordon et al.
[0166] In one embodiment, a portion of the fibers, such as up to
50% or less by dry weight, or from about 5% to about 30% by dry
weight, can be synthetic fibers such as rayon, polyolefin fibers,
polyester fibers, bicomponent sheath-core fibers, multi-component
binder fibers, and the like. An exemplary polyethylene fiber is
PULPEX.RTM., available from Hercules, Inc. (Wilmington, Del.). Any
known bleaching method can be used. Synthetic cellulose fiber types
include rayon in all its varieties and other fibers derived from
viscose or chemically-modified cellulose. Chemically treated
natural cellulosic fibers can be used such as mercerized pulps,
chemically stiffened or crosslinked fibers, or sulfonated fibers.
For good mechanical properties in using papermaking fibers, it can
be desirable that the fibers be relatively undamaged and largely
unrefined or only lightly refined. While recycled fibers can be
used, virgin fibers are generally useful for their mechanical
properties and lack of contaminants. Mercerized fibers, regenerated
cellulosic fibers, cellulose produced by microbes, rayon, and other
cellulosic material or cellulosic derivatives can be used. Suitable
papermaking fibers can also include recycled fibers, virgin fibers,
or mixes thereof. In certain embodiments capable of high bulk and
good compressive properties, the fibers can have a Canadian
Standard Freeness of at least 200, more specifically at least 300,
more specifically still at least 400, and most specifically at
least 500. In some other embodiments, portions of the fibers up to
about 90% by dry weight may be synthetic fibers.
[0167] Other papermaking fibers that can be used in the present
disclosure include paper broke or recycled fibers and high yield
fibers. High yield pulp fibers are those papermaking fibers
produced by pulping processes providing a yield of about 65% or
greater, more specifically about 75% or greater, and still more
specifically about 75% to about 95%. Yield is the resulting amount
of processed fibers expressed as a percentage of the initial wood
mass. Such pulping processes include bleached chemithermomechanical
pulp (BCTMP), chemithermomechanical pulp (CTMP), pressure/pressure
thermomechanical pulp (PTMP), thermomechanical pulp (TMP),
thermomechanical chemical pulp (TMCP), high yield sulfite pulps,
and high yield Kraft pulps, all of which leave the resulting fibers
with high levels of lignin. High yield fibers are well known for
their stiffness in both dry and wet states relative to typical
chemically pulped fibers.
[0168] In some embodiments, the pulp fibers may include softwood
fibers having an average fiber length of greater than 1 mm and
particularly from about 2 mm to 5 mm based on a length-weighted
average. Such softwood fibers can include, but are not limited to,
northern softwood, southern softwood, redwood, red cedar, hemlock,
pine (e.g., southern pines), spruce (e.g., black spruce),
combinations thereof, and the like. Exemplary commercially
available pulp fibers suitable for the present invention include
those available from Neenah Paper Inc. under the trade designations
"LONGLAC-19."
[0169] In some embodiments, hardwood fibers, such as eucalyptus,
maple, birch, aspen, and the like, can also be used. In certain
instances, eucalyptus fibers may be particularly desired to
increase the softness of the web. Eucalyptus fibers can also
enhance the brightness, increase the opacity, and change the pore
structure of the paper to increase the wicking ability of the paper
web. Moreover, if desired, secondary fibers obtained from recycled
materials may be used, such as fiber pulp from sources such as, for
example, newsprint, reclaimed paperboard, and office waste.
Further, other natural fibers can also be used in the present
invention, such as abaca, sabai grass, milkweed floss, pineapple
leaf, and the like. In addition, in some instances, synthetic
fibers can also be utilized. Some suitable synthetic fibers can
include, but are not limited to, rayon fibers, ethylene vinyl
alcohol copolymer fibers, polyolefin fibers, polyesters, and the
like.
[0170] As stated, the paper product of the present invention can be
formed from one or more paper webs. The paper webs can be
single-layered or multi-layered. For instance, in one embodiment,
the paper product contains a single-layered paper web layer that is
formed from a blend of fibers. For example, in some instances,
eucalyptus and softwood fibers can be homogeneously blended to form
the single-layered paper web.
[0171] In another embodiment, the paper product can contain a
multi-layered paper web that is formed from a stratified pulp
furnish having various principal layers. For example, in one
embodiment, the paper product contains three layers where one of
the outer layers includes eucalyptus fibers, while the other two
layers include northern softwood kraft fibers. In another
embodiment, one outer layer and the inner layer can contain
eucalyptus fibers, while the remaining outer layer can contain
northern softwood kraft fibers. If desired, the three principle
layers may also include blends of various types of fibers. For
example, in one embodiment, one of the outer layers can contain a
blend of eucalyptus fibers and northern softwood kraft fibers.
However, it should be understood that the multi-layered paper web
can include any number of layers and can be made from various types
of fibers. For instance, in one embodiment, the multi-layered paper
web can be formed from a stratified pulp furnish having only two
principal layers.
[0172] In accordance with the present invention, various properties
of a paper product such as described above, can be optimized. For
instance, strength (e.g., wet tensile, dry tensile, tear, etc.),
softness, lint level, slough level, and the like, are some examples
of properties of the paper product that may be optimized in
accordance with the present invention. However, it should be
understood that each of the properties mentioned above need not be
optimized in every instance. For example, in certain applications,
it may be desired to form a paper product that has increased
strength without regard to softness.
[0173] In this regard, in one embodiment of the present invention,
at least a portion of the fibers of the paper product can be
treated with hydrolytic enzymes to increase strength and reduce
lint. In particular, the hydrolytic enzymes can randomly react with
the cellulose chains at or near the surface of the papermaking
fibers to create single aldehyde groups on the fiber surface which
are part of the fiber. These aldehyde groups become sites for
cross-linking with exposed hydroxyl groups of other fibers when the
fibers are formed and dried into sheets, thus increasing sheet
strength. In addition, by randomly cutting or hydrolyzing the fiber
cellulose predominantly at or near the surface of the fiber,
degradation of the interior of the fiber cell wall is avoided or
minimized. Consequently, a paper product made from these fibers
alone, or made from blends of these fibers with untreated pulp
fibers, show an increase in strength properties such as dry
tensile, wet tensile, tear, etc.
[0174] Other examples of useful cellulose-based compositions useful
in the present invention include those disclosed in U.S. Pat. Nos.
6,837,970, 6,824,650, 6,863,940 and in U.S. Patent Application
Publication Nos. US20050192402 and 20040149412, each of which is
incorporated herein by reference. Cellulosic webs prepared in
accordance with the present invention can be used for a wide
variety of applications, such as paper and paperboard products
(i.e., other than paper towels), newsprint, uncoated groundwood,
coated groundwood, coated free sheet, uncoated free sheet,
packaging and industrial papers, linerboard, corrugating medium,
recycled paperboard, and bleached paperboard. Webs made according
to the present invention can be used in diapers, sanitary napkins,
composite materials, molded paper products, paper cups, paper
plates, and the like. Materials prepared according to the present
invention can also be used in various textile applications,
particularly in textile webs comprising a blend of cellulosic
materials and wool, nylon, silk or other polyamide or protein-based
fibers.
[0175] The paper products may contain a variety of fiber types both
natural and synthetic. In one embodiment the paper products
comprises hardwood and softwood fibers. The overall ratio of
hardwood pulp fibers to softwood pulp fibers within the product,
including individual sheets making up the product may vary broadly.
The ratio of hardwood pulp fibers to softwood pulp fibers may range
from about 9:1 to about 1:9, more specifically from about 9:1 to
about 1:4, and most specifically from about 9:1 to about 1:1. In
one embodiment of the present invention, the hardwood pulp fibers
and softwood pulp fibers may be blended prior to forming the paper
sheet thereby producing a homogenous distribution of hardwood pulp
fibers and softwood pulp fibers in the z-direction of the sheet. In
another embodiment of the present invention, the hardwood pulp
fibers and softwood pulp fibers may be layered so as to give a
heterogeneous distribution of hardwood pulp fibers and softwood
pulp fibers in the z-direction of the sheet. In another embodiment,
the hardwood pulp fibers may be located in at least one of the
outer layers of the paper product and/or sheets wherein at least
one of the inner layers may comprise softwood pulp fibers. In still
another embodiment the paper product contains secondary or recycled
fibers optionally containing virgin or synthetic fibers.
[0176] In addition, synthetic fibers may also be utilized in the
present invention. The discussion herein regarding pulp fibers is
understood to include synthetic fibers. Some suitable polymers that
may be used to form the synthetic fibers include, but are not
limited to: polyolefins, such as, polyethylene, polypropylene,
polybutylene, and the like; polyesters, such as polyethylene
terephthalate, poly(glycolic acid) (PGA), poly(lactic acid) (PLA),
poly((3-malic acid) (PMLA), poly(.epsilon.-caprolactone) (PCL),
poly(p-dioxanone) (PDS), poly(3-hydroxybutyrate) (PHB), and the
like; and, polyamides, such as nylon and the like. Synthetic or
natural cellulosic polymers, including but not limited to:
cellulosic esters; cellulosic ethers; cellulosic nitrates;
cellulosic acetates; cellulosic acetate butyrates; ethyl cellulose;
regenerated celluloses, such as viscose, rayon, and the like;
cotton; flax; hemp; and mixtures thereof may be used in the present
invention. The synthetic fibers may be located in one or all of the
layers and sheets comprising the paper product.
[0177] Cellulose-based articles can be formed by a variety of
processes known to those skilled in the art. Machines may be
configured to have a forming section, a press section, a drying
section, and depending on the article formed, optionally a reel.
Examples of the details of the process steps and schematic
illustrations may be found in "Properties of Paper: An
Introduction" 2nd edition W. Scott and J. Abbott, TAPPI Press 1995.
In a simplified description of the process, typically a dilute
suspension of pulp fibers is supplied by a head-box and deposited
via a sluice in a uniform dispersion onto a forming fabric of a
conventional papermaking machine. The suspension of pulp fibers may
be diluted to any consistency which is typically used in
conventional papermaking processes. For example, the suspension may
contain from about 0.01 percent to about 1.5 percent by weight pulp
fibers suspended in water. Water is removed from the suspension of
pulp fibers to form a uniform layer of pulp fibers. Other
paper-making processes, paper-board manufacturing processes, and
the like, may be utilized with the present invention. For example,
the processes disclosed in U.S. Pat. No. 6,423,183 may be used.
[0178] The pulp fibers may be any high-average fiber length pulp,
low-average fiber length pulp, or mixtures of the same. The
high-average fiber length pulps typically have an average fiber
length from about 1.5 mm to about 6 mm. An exemplary high-average
fiber length wood pulp includes one available from the Neenah Paper
Inc. under the trade designation LONGLAC 19.
[0179] The low-average fiber length pulp may be, for example,
certain virgin hardwood pulps and secondary (i.e., recycled) fiber
pulp from sources such as, for example, newsprint, reclaimed
paperboard, and office waste. The low-average fiber length pulps
typically have an average fiber length of less than about 1.2 mm,
for example, from 0.7 mm to 1.2 mm.
[0180] Mixtures of high-average fiber length and low-average fiber
length, pulps may contain a significant proportion of low-average
fiber length pulps. For example, mixtures may contain more than
about 50 percent by weight low-average fiber length pulp and less
than about 50 percent by weight high-average fiber length pulp. One
exemplary mixture contains 75 percent by weight low-average fiber
length pulp and about 25 percent high-average fiber length
pulp.
[0181] The pulp fibers used in the present invention may be
unrefined or may be beaten to various degrees of refinement. Small
amounts of wet-strength resins and/or resin binders may be added to
improve strength and abrasion resistance. Useful binders and
wet-strength resins include, for example, KYMENE 557 H available
from the Hercules Chemical Company and PAREZ 631 available from
American Cyanamid, Inc. Cross-linking agents and/or hydrating
agents may also be added to the pulp mixture. Debonding agents may
be added to the pulp mixture to reduce the degree of hydrogen
bonding if a very open or loose nonwoven pulp fiber web is desired.
One exemplary debonding agent is available from the Quaker Chemical
Company, Conshohocken, Pa., under the trade designation QUAKER
2008. The addition of certain debonding agents in the amount of,
for example, l percent to 4 percent, by weight, of the composite
also appears to reduce the measured static and dynamic coefficients
of friction and improve the abrasion resistance of the continuous
filament rich side of the composite fabric. The de-bonder is
believed to act as a lubricant or friction reducer.
[0182] When treating paper webs in accordance with the present
disclosure, the additive composition containing the higher
crystallinity polyolefin dispersion can be applied to the web
topically or can be incorporated into the web by being pre-mixed
with the fibers that are used to form the web. When applied
topically, the additive composition can be applied to the web when
the web is wet or dry. In one embodiment, the additive composition
may be applied topically to the web during a creping process. For
instance, in one embodiment, the additive composition may be
sprayed onto the web or onto a heated dryer drum to adhere the web
to the dryer drum. The web can then be creped from the dryer drum.
When the additive composition is applied to the web and then
adhered to the dryer drum, the composition may be uniformly applied
over the surface area of the web or may be applied according to a
particular pattern.
[0183] When topically applied to a paper web, the additive
composition may be sprayed onto the web, extruded onto the web, or
printed onto the web. When extruded onto the web, any suitable
extrusion device may be used, such as a slot-coat extruder or a
meltblown dye extruder. When printed onto the web, any suitable
printing device may be used. For example, an inkjet printer or a
rotogravure printing device may be used.
[0184] The dispersion may be incorporated at any point in the paper
manufacturing process. The point during the process at which the
dispersion is incorporated into the cellulose-based composition may
depend upon the desired end properties of the cellulose-based
product, as will be detailed later. Incorporation points may
include pre-treatment of pulp, co-application in the wet end of the
process, post treatment after drying but on the paper machine and
topical post treatment. Incorporation of the dispersion of the
present invention onto or in the cellulose-based structure may be
achieved by any of several methods, as incorporated by reference,
and known by those of ordinary skill in the art.
[0185] In yet another application, a higher crystallinity
polyolefin dispersion formed in accordance with the disclosure, is
suitable for impregnating a fibrous structure. In certain cases, a
fibrous structure impregnated with such a stiffening composition
can provide adequate stiffness, elasticity, resilience, adhesion,
and shape retention for use in shoe stiffeners, such as toe boxes,
counters, and the like. Suitable techniques for impregnation are
disclosed in U.S. patent application Ser. No. 11/300,993, which is
expressly incorporated by reference in its entirety.
[0186] One skilled in the art will appreciate that a desirable
degree or amount of impregnation can range from a partial
saturation of the fibrous structure to a complete saturation of the
fibrous structure. The desired degree of impregnation can depend
upon variables including the nature of the fiber being impregnated
and the nature of impregnate, for example. One skilled in the art
will also appreciate that the intended end properties of the
impregnated structure will influence the selection of the specific
ingredients (fibers and dispersions, for example) and processing
parameters.
[0187] In yet another application, dispersions of higher
crystallinity polyolefins may be useful as toner compositions,
wherein at least one selected from the group consisting of a
colorant and a magnetic pigment is used with the dispersion, and
wherein the dispersion has an average volume diameter particle size
from about 0.3 to about 8.0 microns. Techniques for formulating
such toner compositions are discussed in co-pending, co-assigned,
application U.S. Provisional Application Ser. No. 60/779,126 filed
on Mar. 3, 2006, which is expressly incorporated by reference in
its entirety.
[0188] Briefly, after forming the dispersion, at least a portion of
the liquid may be removed to form toner particles. In selected
embodiments, substantially all of the water may be removed to form
base toner particles. In one embodiment, drying of the dispersion
may be accomplished by spray drying the dispersion. As is known in
the art, spray drying involves the atomization of a liquid
feedstock into a spray of droplets and contacting the droplets with
hot air in a drying chamber. The sprays are typically produced by
either rotary (wheel) or nozzle atomizers. Evaporation of moisture
from the droplets and formation of dry particles proceed under
controlled temperature and airflow conditions. Powder is discharged
substantially continuously from the drying chamber. Operating
conditions and dryer design are selected according to the drying
characteristics of the product and powder specification.
[0189] Thus, in one embodiment, a dispersion may be formed, and
shipped to another location, where the dispersion is subjected to a
post-treatment process such as spray drying to form a toner
powder.
[0190] In select embodiments, it is advantageous to add auxiliary
fine particles to the base toner particles in order to improve the
fluidity, the electrification stability, or the blocking resistance
at a high temperature, etc. The auxiliary fine particles to be
fixed on the surface of the base toner particles may be suitably
selected for use among various inorganic or organic fine
particles.
[0191] As the inorganic fine particles, various carbides such as
silicon carbide, boron carbide, titanium carbide, zirconium
carbide, hafnium carbide, vanadium carbide, tantalum carbide,
niobium carbide, tungsten carbide, chromium carbide, molybdenum
carbide and calcium carbide, various nitrides such as boron
nitride, titanium nitride and zirconium nitride, various borides
such as zirconium boride, various oxides such as titanium oxide,
calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum
oxide, cerium oxide, silica and colloidal silica, various titanate
compounds such as calcium titanate, magnesium titanate and
strontium titanate, phosphate compounds such as calcium phosphate,
sulfides such as molybdenum disulfide, fluorides such as magnesium
fluoride and carbon fluoride, various Metal soaps such as aluminum
stearate, calcium stearate, zinc stearate and magnesium stearate,
talc, bentonite, various carbon black and conductive carbon black,
magnetite and ferrite, may, for example, be employed. As the
organic fine particles, fine particles of a styrene resin, an
acrylic resin, an epoxy resin or a melamine resin, may, for
example, be employed.
[0192] Among such auxiliary fine particles, silica, titanium oxide,
alumina, zinc oxide, various carbon black or conductive carbon
black may, for example, be particularly preferably employed.
Further, such auxiliary fine particles may include the above
mentioned inorganic or organic fine particles, where the surface of
the particles is treated by surface treatment such as hydrophobic
treatment by a treating agent such as a silane coupling agent, a
titanate coupling agent, a silicone oil, a modified silicone oil, a
silicone varnish, a fluorinated silane coupling agent, a
fluorinated silicone oil or a coupling agent having amino groups or
quaternary ammonium bases. Such treating agents may be used in
combination as a mixture of two or more of them.
[0193] As a method for adding the auxiliary fine particles to the
base toner particles, a method is known to add and blend them by
means of a high speed stirring machine such as a Henschel mixer.
However, in order to improve the blocking resistance at a high
temperature, it is preferred to have the auxiliary fine particles
fixed on the surface of the base toner particles. In the present
invention, fixing means an addition method employing an apparatus
capable of exerting a compression sharing stress (hereinafter
referred to as a compression shearing treatment apparatus) or an
apparatus capable of melting or softening the surface of the base
toner particles (hereinafter referred to as a particle
surface-melting treatment apparatus). By such fixing treatment, the
auxiliary fine particles may be firmly be fixed to the surface of
the base toner particles without substantial pulverization of the
base toner particles, whereby blocking resistance during the
storage at a high temperature may be improved, and it is possible
to produce a toner which is less likely to bring about fusion to
components of a copying machine or a printer even in a continuous
copying operation.
[0194] The above-mentioned compression shearing treatment apparatus
is constructed to have a narrow clearance defined by a head surface
and a head surface, a head surface and a wall surface, or a wall
surface and a wall surface, which are mutually mobile while a
distance is maintained, so that the particles to be treated are
forcibly passed through the clearance, whereby a compression stress
and a shearing stress will be exerted to the surface of the
particles without substantially pulverizing them. As the
compression shearing treatment apparatus to be used, a
mechanofusion apparatus manufactured by Hosokawa Micron K.K., may,
for example, be mentioned.
[0195] The above-mentioned particle surface-melting treatment
apparatus is usually constructed so that a mixture of the base
toner fine particles and the auxiliary fine particles is
instantaneously heated to a temperature of at least the
melting-initiation temperature by means of for example, a hot air
stream thereby to have the auxiliary fine particles fixed. As the
particle surface-melting treatment apparatus to be used, a
surfacing system manufactured by Nippon Neumatic K.K. may be
employed.
[0196] In yet another application, dispersions using a higher
crystallinity polyolefin may be useful as films, adhesives, or
other sealing and/or packaging applications. This particular
application involves applying a dispersion formulated in accordance
with the above disclosure to a substrate. Those having skill in the
art will appreciate that any useful substrate may be used. In
particular, a wide variety of polymer substrates may be used, and
even more particularly, oriented polymers may be used. Such
techniques are disclosed for example, in U.S. Patent Application
Publication No. 20050271888, which is expressly incorporated by
reference in its entirety.
[0197] In yet another application, dispersions using a higher
crystallinity polyolefin may be useful in forming long
fiber-reinforced thermoplastic concentrates. Techniques for forming
such concentrates are disclosed in co-pending, co-assigned Attorney
Docket No. 64154, which is incorporated by reference in its
entirety.
[0198] While the invention has been described with respect to a
limited number of embodiments, those skilled in the art, having
benefit of this disclosure, will appreciate that other embodiments
can be devised which do not depart from the scope of the invention
as disclosed herein. Accordingly, the scope of the invention should
be limited only by the attached claims.
[0199] All priority documents are herein fully incorporated by
reference for all jurisdictions in which such incorporation is
permitted. Further, all documents cited herein, including testing
procedures, are herein fully incorporated by reference for all
jurisdictions in which such incorporation is permitted to the
extent such disclosure is consistent with the description of the
present invention.
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