Note: Descriptions are shown in the official language in which they were submitted.
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
PRINT RECEPTIVE TOPCOAT FOR INK JET PRINTING MEDIA
COMPRISING A POLYSACCHARIDE AS A BINDER
Field of the Invention
[0001] The present invention relates to an ink-receptive topcoat for ink jet
printing media.
More particularly, the invention relates to an ink-receptive topcoat for ink
jet printing
media, which utilizes a polysaccharide as a binder.
Background of the Invention
[0002] The relatively low cost and convenient use of ink jet printers make
such printers
the generally preferred devices for recording processed images. Ink jet
printing
technology is usually broken down into two categories: continuous flow and
drop-on-
demand printing (including thermal and piezoelectric systems). In a typical
ink jet printing
or recording system, ink droplets are ejected from a nozzle at high speed in a
controlled
mamier to come in contact with a recording media to produce, a printed image
on the
media surface. The ink droplets, or recording liquid, are generally comprised
of a
recording agent, such as a dye or pigment, and a significant amount of a
carrier liquid
component. The carrier liquid is typically water and an organic solvent such
as a
monohydric alcohol, a polyhydric alcohol or mixtures thereof.
[0003] Ink jet recording media is typically composed of a base support layer
having on at
least one surface thereof an ink-receiving or image-receiving coating. Ink jet
media types
include those intended for reflection viewing, which have an opaque support
layer such as
1
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
a paper or pigmented film, and those intended for viewing by transmitted
light, which
have a transparent film support layer.
[0004] Ink jet media are typically used in both Narrow Format and Wide Format
ink jet
imaging devices or printers. Ink jet media is typically used to produce a wide
variety of
printed materials. Narrow Format, or Home/Office printed applications include,
but are
not limited to, newsletters, reports, brochures, catalog sheets, mailing
labels, inventory
control documents, tags, invitations, greeting cards etc. Wide Format, or
business to
business (B2B), printed applications include, but are not limited to, maps,
billboards,
vehicle graphics, banners, posters, and signs.
[0005] The acceptability of recorded images produced with ink jet printers is
in many
cases highly dependent on the recording medium. How well the media prints is
almost
entirely dependent on the quality of the topcoat applied. Key among the
concerns of ink
jet recording media are the requirement of the ink/media to dry quickly after
the ink jet
printing process and the ability to control both the absorption, and spread of
the ink to
provide an acceptable level of print color development and image quality.
[0006] One primary purpose of an ink jet media topcoat is to effectively
absorb the liquid
solvent, or carrier component of the ink jet ink, while providing sufficient
"hold out"
properties which allow the solid pigment or dye component of the ink jet ink
to remain
concentrated near the coated surface and effectively produce an acceptable
quality printed
image. The topcoat provides a base to which the ink can adhere. Without this
coating, the
inks would run, flake off or not dry.
2
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0007] Ink jet media topcoats control dry time of the ink by interacting with
the chemistry
of the ink. The topcoats also regulate drop spread. That is, the ink drop
needs to maintain
a certain circumference at its base. Topcoats prevent the ink drop from
spreading and
flattening. The topcoat also controls how far the ink drop is satarated into
the media,
ensuring that the ink saturates only to a certain point. Without a coating,
many media such
as paper would experience bleed through. The topcoat prevents ink from
saturating these
products and soaking through to the opposite side. Importantly, topcoats
improve image
definition. A smooth coating that controls saturation, bleed-through, spread
and height of
the drop will result in good image definition and image clarity.
[0008] Topcoat options include swellable, porous, and hybrid topcoats. Porous
topcoats
are quick drying, provided they are of sufficient thickness and possess
sufficient pore
volume to effectively contain and control the liquid ink. A porous recording
media coating
can be manufactured containing, a particulate (filler), a binder and a
solvent, or carrier.
[0009] Particulate-containing topcoats are applied to a media support layer
and
subsequently dried bonding them to the media base. The particles are often
silica, but
other materials including calcium carbonate and kaolin are used. The solvent
or carrier
can be either water or an alcohol.
[0010] Typical solvents or carriers include de-ionized water, alcohol
(monohydric or
polyhydric) or a combination thereof. Choice of the carrier, solvent type and
composition
can affect the absorption and drying characteristics of the topcoat during
application to the
base media sheet.
3
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0011] A polymeric binder that is compatible with the aforementioned
components is used
to bind the particles to the paper. The binder helps the absorption of the
carrier liquid of
the ink. The binder material imparts to the base (receiver) sheet improvements
in optical
density and coating adhesion to the substrate, reduced chalking of the applied
topcoat, and
greater paper-like texture of the coated base sheet. Additionally, improved
ink water-
fastness, improved uniformity of solid area printed colors, reduced bi-
directional color
banding in mixed primary colors and reduced inter-color mixing of adjacent
printed colors
result. The binder also serves the function of holding the pigment so as to
reduce or
eliminate dusting or chalking of the ink which results in clogging of the very
fine orifice
nozzles of ink jet printers.
[0012] The binder can be a hydrophilic polymer such as polyvinyl alcohol,
polyvinyl
pyrrolidone, gelatin, cellulose ethers, polyoxazolines, polyvinylacetamides,
partially
hydrolyzed polyvinyl acetate/vinyl alcohol, polyacrylic acid, polyacrylamide,
polyalkylene oxide, sulfonated or phosphated polyesters and polystyrenes,
casein, zein,
albumin, and the like.
[0013] U.S. Pat. No. 4,478,910 which is incorporated by reference herein
discloses a
coating layer comprising a water-soluble polymeric binder and fine silica
particles.
Polyvinyl alcohol or its derivatives is the particularly preferred water-
soluble polymeric
binder.
[0014] U.S. Pat. No. 4,758,461, incorporated by reference herein, describes a
topcoat,
which includes a silicon containing type pigment and an aqueous binder. The
liquid
viscosity of the aqueous coating liquid at 30 C is in the range of 60 to 200
cps. The
4
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
aqueous binder is one or more water-soluble polymers such as polyvinyl
alcohol, starch,
oxidized starch, cationized starch, casein, carboxymethyl cellulose, gelatin,
hydroxyethyl
cellulose and water-dispersed polymers such as SBR latex, MBR latex, vinyl
acetate
emulsion. Polyvinyl alcohol is the preferred binder. The ink jet recording
medium uses
several sizing agents. However, the sizing agents tend to migrate over time in
the
recording medium, thereby causing changes in the ink absorptivity of the
medium and
reducing overall print quality of the recorded medium.
[0015] U.S. Pat. No. 5,270,103, incorporated by reference herein, describes a
coating of a
pigment and a binder, which includes polyvinyl alcohol, and one or more
additional
binder materials. The pigment is a silica, such as a colloidal hydrogel type
amorphous
silica. Additional binders can be a styrene-butadiene latex, a cationic
polyamine, a
cationic polyacrylamide, a cationic polyethyleneimine, a styrene-vinyl
pyrrolidone
copolymer, a styrene-maleic anhydride copolymer, a polyvinyl pyrrolidone, or a
vinyl
pyrrolidone-vinyl acetate copolymer.
[0016] Carbohydrate polymers such as starches and gums can also be used as
binders.
Examples include cellulose derivatives, chitin, chitosan, dextran, pectin,
agar=agar,
arrowroot, guar, carrageenan, tragacanth, xanthan, as exemplified by U.S. Pat.
Nos.
6,610,136, 6,551,695 and 6,495,243, each of which is incorporated by reference
in their
entirety herein. Cornstarch is an inexpensive carbohydrate polymer and is one
of the
lowest binding strength and binding efficiency coating binders that can be
used. Some
disadvantages of the carbohydrate polymers as binders is that the coating
compositions
contain low coating solids, poor rheology, and are expensive to manufacture.
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0017] Prior topcoat compositions for ink jet printing media have several
drawbacks and
disadvantages. Problems exist with previous ink jet media topcoats that effect
printability
and color development.
[0018] Previous ink jet media topcoats do not effectively absorb the liquid
solvent or
carrier component and possess sufficient "hold-out properties" to allow solid
pigment or
dye to remain concentrated near the coated surface. Ink is often absorbed
along the fiber
on the media surface resulting in a phenomenon called feathering. Topcoat
compositions
that possess satisfactory absorbance often produce loss of density and hence,
inaccurate
color reproducibility in the printer image. A correct balance of the
properties is very
difficult to achieve especially at higher print resolutions and smaller dot
diameters. The
result is that in some of the teachings of the prior references, the density,
sharpness, and
roundness of each dot may still not be sufficient to obtain high quality, high
contrast, full
color recorded images for ink jet paper.
[0019] Another problem is that topcoats that use silica particles often
require an excessive
amount of binder for processing the solids to achieve the desired minimal coat
weight.
The suspensions become too viscous to allow pumping and uniform application
using
conventional coaters such as a blade coater. Attempts to use a lower binder
level have
resulted in excessive "dusting" in the finished product.
[0020] Another problem with previous topcoats is known as cockling in which
pulp fibers
are swelled with ink resulting in a wavy deformity or "back-through" in which
ink reaches
the back surface or the paper. Cockling not only impairs image quality but
also produces
scraping between the recording paper and the printer head.
6
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0021] Thus, there is a need for binders for ink jet printing media topcoats
that avoid
most, if not all, of the foregoing problems while addressing the unmet needs
of the
industry. Topcoats that are inexpensive yet produce improved print color
(Chroma)
development, improved print quality, and possess improved ink
absorption/holdout
characteristics are needed.
Summary of the Invention
[0022] The present invention is directed to the use of a polysaccharide as the
binder
component for an ink jet print receptive topcoat and a filler comprised of
silica, which
composition exhibits improved ink jet printing printability and improved color
development.
[0023] It is an object of this invention to provide an ink jet print receptive
topcoat
composition having good ink drying, ink absorption, and/or water resistance
with low
wicking and bleeding together with an acceptable dot density, sharpness and
roundness,
and which is suitable for the recording of high quality, high contrast, full
color
development.
[0024] The foregoing objective is achieved in accordance with the present
invention by
use of a polysaccharide as the binder component of an ink jet media topcoat in
combination with a filler comprised of silica.
[0025] The present invention also provides compositions and methods for using
compositions of media topcoat which includes a filler comprised of silica, a
binder
comprised of a polysaccharide and a carrier wherein a topcoat derived from the
coating
7
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
composition exhibits a high solids content, low viscosity and when dried is
printable with
liquid ink jet printing inks.
[0026] Other embodiments of the present invention also provide a method for
making an
ink jet printing medium with a basesupport layer and an ink receptive topcoat
composition wherein the topcoat is printable with liquid ink jet inks and may
be readily
applied to the base sheet with conventional coating equipment.
[0027] The method for making an ink jet printing medium in accordance with the
present
invention includes the steps of:
preparing a media topcoat comprising a filler comprised of silica, a solvent
or carrier and
a binder comprised of a polysaccharide;
applying the topcoat to at least one side of a substrate; and drying the
topcoat on the
substrate to produce the ink jet printing medium.
[0028] Also contemplated are a printing method and system employing the ink
receptive
topcoat media.
[0029] Still further embodiments of the invention provide printed products of
various
substrates using the ink receptive topcoat media.
[0030] It has surprisingly been found that the use of a polysaccharide in a
binder in the
topcoat for ink jet printing media together with the silica as the filler
results in
significantly improved print color (Chroma) development, improved print
quality through
improved ink absorption/holdout characteristics, and lower coating cost when
compared to
8
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
like media employing a coating containing polyvinyl alcohol or
polyvinylpyrrolidone as a
binder.
[00311 Polydextrose as the binder is especially preferred. The effectiveness
of using
polydextrose as the binder element is based on the 1) function of polydextrose
as an
effective water-based dye solubilizer and, 2) the pH neutral characteristics
of polydextrose
acting to minimize dye color shifts resulting in a more pure Chroma value.
Brief Description of the Drawings
[0032] FIG. 1: depicts the linkage distribution of FIBERSOL-2 versus
polydextrose.
[0033] FIG. 2: depicts the summary of linkage and branching for FIBERSOL-2
compared to polydextrose.
Detailed Description of the Invention
[0034] The print-receptive topcoat for ink jet printing media of the present
invention
comprises a filler comprised of silica, a binder comprised of a polysaccharide
and a
carrier.
[0035] The print receptive topcoat of the present invention absorbs the liquid
component
of the ink better than previous media, and provides a quicker ink drying time,
while
preventing bleeding or diffusion of the ink into the substrate media.
Additionally, the
topcoat causes the ink pigment to be fixed on the media in the form of well-
defined dots
of uniform size and shape. Moreover, the topcoat of the present invention
features
superior color depth.
9
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0036] Applicants have surprisingly discovered that ink receptive coating
formulations
employing a polysaccharide, as a binder could be produced at high solids
levels resulting
in relatively low viscosities, enabling a broader range of coating technology
methods used
in the actual topcoat deposition to an ink jet media substrate.
[0037] The low viscosity facilitates pumping, prevents clogging of the
applicator nozzle.
Low viscosity facilitates uniform application using conventional coaters such
as blade
coaters.
[0038] The term "ink jet printing media" is used interchangeably with
"substrate" and
refers to materials upon which the ink and topcoat formulation are applied.
Any suitable
substrate or media can be employed. Examples of suitable ink jet printing
media include
paper, card stock, metal, wood, plastic, tape, film, or combinations thereof.
[0039] Topcoat formulations produced with a polysaccharide, such as
polydextrose and/or
an indigestible polysaccharide, or dextrinized oligosaccharide in combination
with silica
yield better color development over those containing PVP. A distinct advantage
of using
polydextrose and/or an indigestible polysaccharide or dextrinized
oligosaccharide or
combination thereof in ink jet topcoat formulations is the capability of
producing high
solids/ low viscosity formulas with improved color development over PVP based
formulations. This advantage allows for the application of the topcoat
utilizing a broad
range of coating application processes and technologies.
[0040] Polysaccharides are defined as sugar polymers with more than 10
residues.
Oligosaccharides are defined as sugar polymers with 2-10 residues. It is
understood that
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
while the term polysaccharides is used throughout, the term encompasses
oligosaccharides
as well. Therefore, the term "polysaccharide" is inclusive of oligosaccharides
as well.
While theoretically there is no limit to the number of residues for the
polysaccharides of
the present invention, practical limitations are based on solution properties,
e.g. solubility
and viscosity. The lower limit of residues of the oligo- and polysaccharides
of the present
invention is based on solubility and the,ability to bind with the paper and
not wash off
easily or cause blocking.
[0041] Oligosaccharides and polysaccharides as defined herein may be homo- or
heterosacchraides. Homosaccharides are based essentially upon a single sugar,
e.g.
glucooligosaccharides or fructooligosaccharides, and may contain a single
linkage type
such as maltooligosaccharides (a-1,4-linkages) or a mixture of linkages,
e.g.,isomaltooligosaccharides (a-1,4-and a-1,6-linkages). Heterosaccharides
contain more
than a single sugar residue, e.g., arabinogalacatan (arabinose and galactose).
As defmed
herein the polymers may be linear or branched.
[0042] Suitable oligosaccharides and/or polysaccharides include, but are not
limited to,
maltooligosaccharides (maltodextrin), isomaltooligosaccharides, cyclodextrins,
gentiooligosaccharides, nigerooligosaccharides, frcictooligosaccharides,
inulin,
galactooligosaccharides, xylooligosaccharides, agarooligosaccharides,
mannooligosacchradies, chitin/chitosan oligosaccharides, arbinogalactan and
pullulan.
[0043] The term "polydextrose" includes polymer products of glucose which are
prepared
from glucose, maltose, oligomers of glucose or hydrolyzates of starch, which
are
polymerized by heat treatment in a polycondensation reaction in the presence
of an acid
11
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
e.g. Lewis acid, inorganic or organic acid, including monocarboxylic acid,
dicarboxylic
acid and polycarboxylic acid, such as, but not limited to the products
prepared by the
processes described in U.S. Pat. Nos. 2,436,967, 2,719,179, 4,965,354,
3,766,165,
5,051,500, 5,424,418, 5,378,491, 5,645,647 5,773,604, or 6,475,552, all of
which are
incorporated by reference herein in their entirety.
[0044] The term "polydextrose" also includes those polymer products of glucose
prepared
by the polycondensation of glucose, maltose, oligomers of glucose or starch
hydrolyzates
described hereinabove in the presence of a sugar alcohol, e.g. polyol, such as
in the
reactions described in U.S. Pat. No. 3,766,165, which is incorporated by
reference herein.
Moreover, the term polydextrose includes the glucose polymers, which have been
purified
by techniques described in the art, including any and all of the following but
not limited
to:
(a) neutralization of any acid associated therewith by base addition
thereto, or by passing a concentrated aqueous solution of the polydextrose
through an adsorbent resin, a weakly basic ion exchange resin, a type II
strongly
basic ion-exchange resin, mixed bed resin comprising a basic ion exchange
resin,
or a cation exchange resin, as described in U.S. Patent Nos. 5,667,593 and
5,645,647, each of which is incorporated by reference herein; or
(b) decolorizing by contacting the polydextrose with activated carbon
or charcoal, by slurrying or by passing the solution through a bed of solid
adsorbent or by bleaching with sodium chlorite, hydrogen peroxide and the
like;
12
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
(c) molecular sieving methods, like ultrafiltration, RO (reverse
osmosis), size exclusion, and the like;
(d) or enzymatically treated polydextrose or,
(e) any other recognized techniques known in the art.
[0045] Moreover, the term polydextrose includes hydrogenated polydextrose,
which, as
used herein, includes hydrogenated or reduced polyglucose products prepared by
techniques known to one of ordinary skill in the art. Some of the techniques
for
preparation are described in U.S. Pat. Nos. 5,601,863, 5,620,871 and
5,424,418, all of
which are incorporated by reference herein. The term polydextrose also
encompasses
fractionated polydextrose that is a conventional, known material and can be
produced, for
example, by the processes disclosed in U.S. Pat. Nos. 5,424,418 and 4,948,596,
which are
incorporated by reference herein.
[0046] Polydextrose is commercially available from a variety of companies
including
Danisco Sweeteners, A. E. Staley and Shin Dong Bang (Korea). Purified forms of
polydextrose are marketed by Danisco Sweeteners under the name LITESSE or
LITESSE II and by A. E. Staley under the name STALITE III . A reduced form of
polydextrose is called LITESSE ULTRA .
[0047] In another embodiment, the polysaccharide binder of the invention is an
indigestible polysaccharide. A preferred example of an indigestible
polysaccharide is
indigestible dextrin(s). Indigestible dextrin is a highly branched
polysaccharide derived by
pyroconversion from starch. Starch is made of glucose molecules attached by a-
(1,4)
13
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
bonds, with some branching by means of a-(1,6) bonds. The degree of branching
is
dependent on the source of the starch.
[0048] The indigestible dextrin is produced from starch in a heat treatment
process known
as pyroconversion. Pyrodextrins are starch hydrolysis products obtained in a
dry roasting
process either using starch alone or with trace levels of acid catalyst. The
first product
formed in this reaction is soluble starch, which in turn hydrolyzes further to
form dextrins.
The molecular weight of the final product depends on the temperature and
duration of
heating. Transglucosidation can occur in the dextrinization process, in which
rupture of an
a-(1,4) glucosidic bond is immediately followed by combination of the
resultant
fragments with neighboring hydroxyl groups to produce new linkages and
branched
structures. Thus, a portion of the glycosidic bonds are scrambled. A
commercially
available pyroconverted starch is called FIBERSOL-2 and is available from
Matsutani
America, Inc.
[0049] Another preferred polysaccharide includes the indigestible
polysaccharide
described in U.S. Patent No. 5,620,871, the contents of which are incorporated
by
reference.
[0050] U.S. Patent No. 5,620,871 discloses a method for preparing indigestible
polysaccharides by canying out an enzymatic hydrolysis of a dextrin or
polysaccharide
using at least one saccharifying enzyme and at least one enzyme which
hydrolyzes the 1-6
bonds of amylopectin.
14
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0051] Another preferred example of polysaccharide used as a binder in the
present
application is described in JP Patent Publication No. 2001/086946, the
contents of which
are incorporated by reference. It describes a hydrogenated starch hydrolysate
containing
non-digestible polysaccharides which are obtained by hydrolyzing starch with
(3-amylase
followed by hydrogenation of the thus treated dextrin.
[0052] A further preferred example of an indigestible polysaccharide is
described in JP
62-091501, the contents of which are incorporated by reference. It discloses
an
indigestible polysaccharide prepared by hydrogenating a starch hydrolyzate
obtained from
acid or enzyme saccharification of starch, e.g., reduced branched dextrin, in
the presence
of an acid catalyst, e.g., 0.3-0.5 wt% inorganic acid (e.g., phosphoric acid)
or 5-20 wt%
organic acid, (e.g., citric acid,) to produce a reduced starch hydrolyzate,
which is then
dried by heating to 130 C in a vacuum. The dried product is then heated to 150
C-250 C
for 1-3 hours to obtain a powdered indigestible polysaccharide comprising an
aggregate of
a non-reducing polymer of various degrees of polymerization, formed by
rearrangement
of the glucose residue of the non-reducing sugar mainly at the 1-6 linkage.
[0053] Another preferred example of a polysaccharide as used herein is
dextrinized
oligosaccharide, which as used herein, is a saccharide - derivatized
oligosaccharide which
is described in U.S. Patent Application Publication No. U.S. 2004/0053866, the
contents
of which are incorporated by reference. It is a saccharide - derivatized
mixture
comprising the extrusion reaction product of a saccharide product having an
average
degree of polymerization ranging from 1 to 4 with a mixture of malto -
oligosaccharide.
As used herein a malto-oligosaccharide is a species comprising two or more
saccharide
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
units linked predominantly via 1-4 linkages. It is preferred that the
maltooligosaccharide
used is maltodextrin.
[0054] The more preferred binders are indigestible dextrin polydextrose, the
indigestible
polysaccharide described in U.S. Patent No. 5,620,871, JP 62-091501 and JP
2001/086946 and the dextrinized oligosaccharide, maltooligosaccharides
(maltodextrin),
isomaltooligosaccharides, cyclodextrins, gentiooligosaccharides,
nigerooligosaccharides,
fructooligosaccharides, inulin, galactooligosaccharides, xylooligosaccharides,
agarooligosaccharides, mannooligosacchradies, chitin/chitosan
oligosaccharides,
arbinogalactan and pullulan. Examples of preferred polysaccharides include,
but are not
limited to, polydextrose, indigestible dextrin(s), and derivatives thereof,
and combinations
thereof. A most preferred polysaccharide is polydextrose. The most preferred
binders are
indigestible dextrin and especially polydextrose.
[0055] It is to be noted that the binder may consist of one polysaccharide or
a combination
of two or more polysaccharides as defined herein.
[0056] In an embodiment of the present invention, the polysaccharide in
whatever form
utilized is substantially pure. It is preferred that they are substantially
free of impurities.
They are preferably at least about 80% pure and more preferably at least about
85% pure
and most preferably at least about 90% pure.
[0057] The binder can be purified using techniques known in the art. For
example,
among the purification processes used in the art, the following are preferred
processes for
purifying polydextrose: 1) bleaching, e.g. using hydrogen peroxide (described
in U.S. Pat.
16
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
No. 4,622,233); 2) membrane technology (described in U.S. Pat. No. 4,956,458);
3) ion
exchange e.g. removal of citric acid (described in U.S. Pat. No. 5,645,647) or
removal of
color/ bitter taste (described in U.S. Pat. No. 5,091,015); 4) chromatographic
separation,
with a strong cation exchanger (described in W092/12179); 5) hydrogenation, in
combination with ion exchange (described in U.S. Pat. Nos. 5,601,863 and
5,573,794) or
6) with ion exchange and chromatographic separation (described in U.S. Pat.
No.
5,424,418); or 7) solvent extraction (described in U.S. Pat. No. 4,948,596 and
EP 289
461), the contents of each of these patents being incorporated by reference
herein.
[0058] Figures 1 and 2 show the summary of linkages and branching in FIBERSOL-
2
and polydextrose. The FIBERSOL-2 compared to polydextrose has higher amounts
of
unbranched and single branched residues, lower content of furanoses and
greater amounts
of 4- and 4,x- linked residues. Polydextrose, in which 6-linkages predominate,
is more
highly branched than FIBERSOL-2 and FIBERSOL-2 contains far more 4-linkages,
in
keeping with its starch origin. Despite these differences, polydextrose and
FIBERSOL-2
are very closely related in structure and either can be used alone or in
combination in the
binder of the present topcoat composition.
[0059] The polysaccharide, e.g., polydextrose or derivatives thereof, e.g.
LITESSE or
LITESSE II , act as a binder. LITESSE II is preferred because of low costs.
Likewise,
the indigestible dextrin or derivatives thereof,-e.g. FIBERSOL-2 , acts as a
binder. The
polydextrose or the indigestible polysaccharide, or the dextrinized
oligosaccharide e.g., in
the "binder" improves the film forming capability of the coating. Without
wishing to be
17
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
bound it is believed that its hydrophilic nature thereof facilitates the
absorption of the ink
jet ink by the coating during the ink jet printing process.
[0060] The binder of the present invention comprised of polysaccharide, e.g.,
polydextrose, indigestible polysaccharide, dextrinized oligosaccharide or
combination
thereof is present in amounts effective to enhance ink jet printability and
improve color
development. It is preferred that the binder, i.e., polydextrose or
indigestible
polysaccharide or dextrinized oligosaccharide is present in the range from
about 5% to
about 93% on a parts by solid weight basis. The preferred concentration of the
polydextrose and/or indigestible polysaccharide binder is about 50% to about
70% on a
parts by solid weight basis.
[0061] Optionally, other binders can be combined with the binders discussed
above.
Suitable binders include, but are not limited to gums, cellulose derivatives,
chitin,
chitosan, dextran, pectin, agar-agar, arrowroot, guar, carrageenan,
tragacanth, xanthan,
gelatin, polyvinylpyrrolidone and copolymers thereof, and/or hydrophilic
polymers such
as polyvinyl alcohol (PVOH), polyvinyl pyrrolidone, gelatin, cellulose ethers,
polyoxazolines, polyvinylacetamides, partially hydrolyzed polyvinyl
acetate/vinyl alcohol,
polyacrylic acid), polyacrylamide, polyalkylene oxide, sulfonated or
phosphated
polyesters and polystyrenes, casein, zein, albumin, and the like. An example
of a binder
suitable for the present invention which may be added is Celvol 08-125
poly(vinyl
alcohol) binder.
[0062] In one embodiment of the invention, a topcoat is provided that is
comprised of a
mixture of a silica filler, and the binder is comprised of a polysaccharide,
e.g.,
18
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
polydextrose or indigestible dextrin. The components can be dissolved, or
dispersed into
a solvent solution or carrier comprised of deionized water, a suitable alcohol
or a
combination of the two. Other components can be added to improve coating wet
out (or
spread) of the coating during application to the ink jet media base support
layer, improve
the pot life or working time of the coating during application, impart other
properties to
the coating or to modify the viscosity or solids content of the coating and/or
act as a
biocide agent.
[0063] Drying and surface holdout of the printed inks on the topcoat are
facilitated by the
addition of a pigment or filler. The pigment or filler not only aids in
surface holdout of the
ink but also introduces pores or channels to the topcoat to aid in drying. The
filler, i.e.,
silica, content of the invention results in the ink absorptive nature of the
coating and is
partially responsible for the pennanent nature of the adhesion of the ink to
the coated
media base. The binder of the present invention, e.g., polydextrose, aids in
binding of the
silica to the paper substrate. The preferred filler is silica. A variety of
silica types are well
known, available, and suitable for use such as fumed silica, precipitated
silica, and silica
gel. Silica types exhibit different pore sizes resulting in varying degrees of
ink absorbing
capabilities. A fumed silica gel dispersion particularly suitable for the
present invention is
CAB-O-SPERSE PG001 (produced by the Cabot Corporation), which possesses high
pore
volume and ready dispersion into the solvent solution.
[0064] Concentration of the silica filler component can range from about 0% to
about
90% on a parts by weight basis and are covered under this invention. The
preferred
concentration of the silica gel filler is from about 25% to about 50%.
19
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0065] It is understood that other fillers may be used together in addition to
the silica,
including, but not limited to calcium carbonate, kaolin, and mixtures thereof.
[0066] Other ingredients or additives may be added to avoid problems which
occur during
mixing and application such as improper wetting of the substrate surface,
foaming of the
composition when exposed to high mixing rates, adhesion of the dry composition
to the
substrate, and preservation of the components from biological attack (e.g.
fungi). For
example, non-ionic surfactants, defoamers or preservatives may be added. An
example of
a defoamer suitable for the present invention is FOAMASTER 111 silicone based
defoamer. An example of a suitable preservative for the present invention is
PROXEL
GXL.
[0067] Further, the ink jet printing media topcoat of the present invention
can contain an
additive such as a biocide, an anti-curling agent or anti-blocking agent. The
topcoat can
also contain other additives known to those skilled in the art to improve the
print image,
such as, but not limited to, for example, UV absorbers, optical brighteners,
light
stabilizers, antioxidants, humefactants, spacing agents, plasticizers, dye
mordants,
fixatives, dispersants, rheology modifiers, leveling agents and the like.
[0068] In a preferred embodiment, the ink jet topcoat also includes a
surfactant to charge
the pigment. Preferred surfactants are nonionic. However, cationically or
anionically
charged surfactants can also be used. An example of a suitable surfactant
includes, but is
not limited to, polyethylene glycol (TRITON X-100 ) (DOW-UCAR). The surfactant
is
employed at a concentration of about 0.1 % to about 5% on a parts by weight
basis, and
more preferably at about 0.5% to about 2% on a parts by weight basis.
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0069] In still another embodiment, the topcoat of the present invention
includes a biocide
agent. An example of a suitable biocide agent is PROXEL GXL (1,2-
Benzisothiazolin-3-
one, produced by Avecia Biocides), with a concentration in a range of about 0%
to about
1% on a parts by weight basis.
[0070] The topcoat solvent or carrier liquid can be deionized water,
monohydric alcohol,
polyhydric alcohol or a combination thereof. Preferred is deionized water.
Typical
concentration of the solvent or carrier liquid can range from about 50% to
about 85% on a
parts by weight basis. Deionized water is preferably ion-exchanged water of
which the
Ca'2 ion and Mg+2 ion contents have been reduced to not more than about 5 ppm.
[0071] The topcoat coating will preferably have a dried thickness of about 0.1
to about 0.5
mils, or from about 2 to about 13 grains/square meter. However, topcoat
thickness in a
range from about 1 to about 25 grams/square meter or more can be effective.
Actual
topcoat coating thickness within this range can be variable based on the
specific ink jet
media base being coated. The invention covers all ranges of dried coating
thicknesses as
noted.
Method of Preparation
[0072] The topcoat of the present invention is formulated by adding the silica
filler
component to deionized water while mixing under a mild level of agitation
until
homogeneous. The binder is then added to the deionized water solution and
mixed under a
mild level of agitation until homogeneous. Mixing is performed with a spindle
with
multiple blades in an open vessel. The rate of mixing is that which results in
a
21
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
homogeneous mixture without inducing foaming. The addition of other
components, as
noted earlier, including surfactants, biocides, and the like, are added in
succeeding steps as
required to improve the coatability, or extend the pot life/stability of the
coating.
[0073] The order of adding additives is based on ingredient functionality. For
example,
the defoamer is added to deionized water prior to the addition of the
polysaccharide and,
optionally, additional binders to inhibit the foaming from the addition of
those ingredients.
Cationic mordants such as AgeflexTM are added subsequent to the silica filler
to inhibit
flocculation of the silica particles.
[0074] The total solids content of the compounded ink jet topcoat composition
can range
from about 10% to about 50% on a parts by weight basis. The viscosity of the
compounded topcoat can range from about 10 to about 20 cps (centipoise). Both
the solids
content and the viscosity of the compounded topcoat can be varied or adjusted
based on
actual coating requirements dictated by the method of applying the topcoat
composition to
-the ink jet media base layer that is to be coated.
[0075] The invention can be applied, or coated onto an ink jet media base
support layer
using a variety of commonly known coating techniques. The ink jet media, or
base
support layer, can be an uncoated paper, a coated paper (coated on one side or
two sides),
a polymer film, a laminate of paper and film or other suitable material useful
in ink jet
printing. Preferred substrates are paper and paper type media.
[0076] Any application method known to those skilled in the art can be
employed to apply
the ink jet topcoat to the ink jet media base. Topcoat application techniques
that can be
22
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
used include, but are not limited to, wire wound rod, metering bar, knife over
roll, direct
gravure, reverse gravure, reverse roll and multiple roll methods, and air
knife. These
coating methods can be employed as a secondary process to apply, or coat the
topcoat
composition onto an ink jet media base after manufacturing of the media base.
[0077] The ink jet topcoat of the present invention can also be applied to a
paper ink jet
media base in a size press during the media manufacturing process of a base
paper. In
addition, the ink jet topcoat of the present invention can be applied to the
ink jet media
base during a secondary printing, or converting operation, during which the
ink jet media
can undergo actual printing and die-cutting operations after application of
the topcoat as in
the case of labels. The ink jet topcoat would then be applied prior to the
printing, and die
cutting operations.
[0078] It is understood that the topcoat of the present invention can be
applied to one or
both sides of the media substrate. Additionally, other coats such as anti-curl
coats can be
applied.
[0079] After application of the ink jet topcoat to, and absorption by, the ink
jet media base
layer the ink jet topcoat is dried to drive off the solvent carrier liquid
from the topcoat
composition. The drying process can be accomplished through the use of any
drying
method known to those skilled in the art. Preferred are evaporative drying
processes.
Drying processes that can be used in the present invention include, but are
not limited to,
air drying, convection, radio frequency, or infrared methods.
23
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0080] Noting that to date, no unifying theory that explains molecular
interactions which
take place between the ink jet medium topcoat and the medium itself, the
present
invention should not be limited to a particular theory of operation. In
general, to obtain an
image of high chroma, it is believed, without wishing to be bound, that the
ink jet printing
ink (dye or pigment based) coloring material should be retained on the surface
of a
recording medium in a monomolecular state without aggregation. When
aggregation of
the ink jet printing ink material on the surface of the recording medium
occurs, Chroma
can be lowered. The superior color development of the compositions of the
invention
results from the presence of the binder, i.e., a polysaccharide, e.g.,
specific range of linear
and branched oligomers, and low to high molecular weight range (DP
distribution) in
polydextrose or FIBERSOL-2 combined with its highly amorphous nature which
inhibits
aggregation of the coloring material.
[0081] The most preferred binder is polydextrose. When polydextrose was used
as the
binder in topcoat compositions, prepared in accordance with the present
invention,
formulation evaluations showed polydextrose to function as an effective binder
for paper
ink jet media coatings. Without wishing to be bound, it is believed that
polydextrose is
preferred due to its natural affinity for paper and its effectiveness in
solubilizing water-
based dyes. A preferred ink receptive coating is formulated containing
polydextrose.
[0082] In another embodiment, black pigment ink hold out on the printed
surface was
optimized via modification of the coating formulation with cationic dye
mordant and use
of polyvinyl alcohol (PVOH) as a co-binder.
24
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0083] Paper samples coated with an optimized formulation containing the
binder utilized
in the present invention, i.e., polysaccharides, e.g., polydextrose or
indigestible
polysaccharide or dextrinized oligosaccharide or combination thereof in
combination with
the filler comprised of silica, e.g., showed improved physical properties when
compared
with commercially available topcoated ink jet printing papers. Physical
properties include,
but are not limited to, curl (ASTM D 4825), blocking (ASTM D 918), and
smoothness
(TAPPI T-53 8). The ink receptive layer can absorb water in the air and swell
in an
environment of high relative humidity, causing curling. Sheffield smoothness
is a
measurement of pressurized air flow over the surface under prescribed
conditions.
[0084] Paper samples coated with the composition of the present invention
containing
polysaccharide or combination thereof as the binder and a filler comprised of
silica
showed improved printing quality in most aspects. Print quality assessments
include curl,
feathering, mottling, wet or dry cockle, image bleed, banding, bronzing, skew
or artifacts.
Feathering is a phenomenon that is evidenced primarily in printed text and is
caused by
ink flowing along fibers in the paper. Visual evidence of feathering is small
protrusions
around the edges of a printed image. Mottling is defined as printing defects
resulting in
non-uniform print density of a solid filled area. Coalescence is defined as
printing defects
caused by pooling of ink in areas on the surface of the paper. Wet cockle is
evidenced by
wave patterns during application of wet ink to the paper surface. Dry cockle
is the result
of non-unifonn print densities arising from wet cockle. Image bleed can be
visually
evidenced by the mixing of one ink color with another adjacent ink color.
Bleed is usually
a result of severe feathering. Banding is evidenced by regions of bands of
varying print
density in a solid filled area. Bronzing is the appearance of a bronze sheen
to solid filled
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
black print areas. Skew relates to the position of printed images to the
border of the paper.
Artifacts include any droplets or ink spray located in unprinted areas of the
paper. Issues
relating to mottling/coalescence and wet/dry cockle are likely due to the
coating
techniques used.
[0085] The use of the composition of the present invention provided enhanced
print
quality, decreasing the amount of and more preferably minimizing the amount of
curl,
feathering, mottling, cockling, bleeding, banding, bronzing, and the presence
of artifacts
relative to a composition in which the silica and polysaccharide binder are
not present.
[0086] The overall print quality of paper coated with the polysaccharide,
e.g.,
polydextrose, formulation was compared to that of commercial ink jet printable
paper and
showed the following advantages: (1) improved printability; (2) improved
printed color
purity (Chroma) for dye-based inks; and (3) comparable-to-improved physical
properties
over commercially available ink jet printable papers.
[0087] Commercially available ink jet products provide examples of suitable
ink jet
printing media which the print receptive topcoat of the present invention can
be applied to.
It is understood that the media can be paper, card, stock, metal, wood,
plastic, or film.
[0088] As used herein, unless indicated to the contrary, the plural denotes
the singular and
vice versa.
[0089] By percent on a weight basis as used herein is meant percentages in the
composition which includes the liquid carrier component.
26
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[0090] The following examples serve to provide further appreciation of the
invention but
are not meant in any way to restrict the effective scope of the invention.
[0091] While not wishing to be limited to a particular theory of operation,
for purposes of
the experimental coating of materials, a conventional laboratory drawdown
coating device
employing a wire-wound rod to apply and meter the coating was employed.
EXAMPLE 1
[0092] An ink jet receptive top coating for paper was formulated as set forth
in Table 1.
Polydextrose was formulated with the nonionic surfactant polyethylene glycol
(TRITONo) (Dow), fumed silica (CAB-O-SIL ) (Cabot Corporation), and a biocide
(PROXEL GXL ) (1,2=Benzisothiazolin-3-one, Avecia Biocides).
Table 1
Polydextrose 10.0%
Cab-O-Sil S-610' 5.0%
Triton X-100 1.0%
Proxel GXL 0.1%
Deionized water 83.9%
[0093] Mixing of the formula components was conducted with a Caframo RZR 1
electric
mixer operating at medium to low shear agitation. Mixing was continued until
visual
homogeneity was obtained without any foaming. The formulation was then flood-
coated
27
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
onto a 60 lb/ream offset opaque paper. Examples of opaque paper include HuSky
Offset
(manufactured by Weyerhaeuser) and Pristine Opaque (manufactured by Eastern
Paper)
Using a meyer rod (wire wound rod) employing a ChemInstruments EZ-2002
laboratory
coater the coating was applied to the substrate to achieve target coating
weights from
about 2 grams to about 6 grams per square meter range.
[0094] Initial ink jet printing was performed using an HP DeskJet 6122 printer
with dye-
based color ink (HP C6578DN) and pigment-based black ink (HP 51645A). The
pattern
chosen included blocks of the following colors: cyan, magenta, yellow, black,
red,
orange, blue, and green. Printed samples showed good visual color development
over the
uncoated base paper printed in a similar manner.
EXAMPLE 2
[0095] Modifications to optimize the ratio of polydextrose and silica as well
as the final
coating solids were undertaken. A silica dispersion (CAB-O-SPERCE PG001')
(Cabot
Corporation) was used in place of CAB-O-SIL fumed silica to aid in ease of
formulation.
Eight formulations (B through I) as set forth below in Table 2 were prepared
with varying
polydextrose to silica ratios while holding other ingredients constant.
28
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
Table 2
Formulations B through I
B C D E F G H
Pblycimroee 1 1 1 1 2 4 9
UA)_~ 18 5 3 1 1 1 1 0
PCD01
[0096] The percentage of overall solid material in the formulations was kept
constant.
Little to no change in viscosity was seen with the addition of more
polydextrose.
[0097] Visual investigations of printed dye-based color inks and pigment-based
black ink
were made. Subjective rankings were assigned based on the visual appearance of
printed
samples. Printed samples were ranked from best (1) to worst (8) in appearance.
Rankings
are listed in Table 3.
29
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
Table 3
Rankings from Visual Inspection of Printed Samples
B C D E F G H I
dye-based 8 4 2 2 1 5 6 7
color inks
pigment 8 7 6 4 4 2 2 1
black ink
overall 8 7 4 2 1 3 4 4
rank
[0098] An apparent "optimum state" was observed wherein the addition of
additional
polydextrose does not visually improve dye-based color ink appearance.
However, the
combining of additional amounts of polydextrose improved the overall
appearance of
printed pigment-based black ink. Formulation F resulted in the best overall
coating for
visual appearance of dye-based color ink and pigment-based black ink.
EXAMPLE 3
[0099] Variations in the solid levels of Formulation F and the effect on
viscosity are
found in Table 4.
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
Table 4
Solids Versus Viscosity
F F-1 F-2 F-3 F-4
solids level 16% 20% 25% 30% 35%
viscosity 12.0 14.5 18.0 22.5 30.0
(cPs)
[00100] Viscosity has a potentially large effect on determination of
application
method of a coating to paper. Increasing the solids content in formulations
with
polydextrose caused only a slight increase in viscosity. This indicates that a
broad range of
coating application technologies and methods are potentially suitable for the
deposition of
a polydextrose-based binder topcoat to the ink jet media base.
EXA.MPLE 4
[00101] The performance of polydextrose as an ink receptive coating component
was compared to patented formulations for ink jet receptive top coatings
employing
poly(vinyl alcohol) (PVOH) and/or poly(vinyl pyrrolidone) (PVP) for viscosity
and visual
appearance with printed dye-based color inks and pigment-based black ink. The
patent
formulations used for comparison, i.e., WO 95/06564, U.S. Pat. No. 4,775,594
and WO
02/43965 are found in Tables 5-7 below, respectively. Table 8 lists rankings
from visual
inspection of the printed samples. Table 9 provides comparisons of viscosity.
31
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
Table 5
Patent Formulation PVOH I (WO 95/06564)
Celvol 125 t 9.0%
Cab-O-Sperse PG001 0.2%
K-90 (PVP) ff' 1.0%
deionized water 89.8%
t: available from
Celanese Chemicals
tt: available from ISP
Techologies
Table 6
Patent Formulation PVP I (US 4775594)
Dowanol PM 0* 43.3%
Zonyl FSJ '' a 0.5%
tt: available from ISP
Techologies
ttt: available from
*: available from Aldrich
a: available from
DuPont
32
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
Table 7
Patent Formulation PVP II (WO 02/43965)
K-90 (PVP) ~tt 9.1%
Syloid 620 ** 3.9%
n-butanol 43.3%
tt: available from ISP Techologies
**: available from Grace Davison
[00102] Coatings were produced on 60 lb/ream offset opaque base paper at
similar
coating weights. A visual comparative ranking of the appearance of the printed
inks was
made of the patent formulations and Formulation F as described in Table 8.
Table 8
Rankings from Visual Inspection of Printed Samples
F PVOH I PVP I PVP II
dye-based 1 2 3 4
color inks
pigment 4 1 3 2
black ink
overall 2 1 3 3
rank
33
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[00103] Formulation F coating overall exhibited improved (the best) dye-based
color ink appearance as well as inferior pigment-black ink appearance when
compared to
the patent formulations. The visual appearance of printed samples was slightly
better than
formulations based on PVP alone, however, the visual appearance was not
comparable to
printed sample with PVOH and PVP co-binders in the top coating.
Table 9
Viscosity Comparison Table
F PVOHI PVPI PVPII
solids 16.0% 10.0% 13.1% 10.0%
viscosity 12 1631 1387 593
(cPs)
[00104] Formulation F, at slightly higher solids than the three patent
formulations,
exhibited the lowest viscosity. Formulations involving PVOH or PVP are well
known for
exhibiting viscosity increases with increasing solids levels. Formulations
with
polydextrose do not exhibit this trend.
EXAMPLE 5
[00105] Additional modifications were made to optimize Formulation F to aid in
pigment-based black ink appearance. Visual inspection of the printed pigment-
black areas
34
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
indicated a less than desirable level of hold out of the pigment on the
surface of the coated
paper. To improve the black pigment ink holdout, the following modifications
were
made: (1) crosslinking of the polydextrose, (2) addition of cationic dye
mordants, and (3)
use of co-binders.
[00106] Polydextrose contains high concentrations of free hydroxyl groups that
can
potentially be used in crosslinking polymer chains. Titanates, an example
being TYZOR
product line (DuPont) and isocyanates, an example being DESMODUR0 (Bayer) are
widely known and used for crosslinking of hydroxyl chemistries. Various
crosslinkers
were evaluated with Formulation F at concentrations known to those in the art.
Evaluation
of thermally crosslinked coatings shows no visual improvement of the pigment-
based
black ink hold out on the surface.
[00107] Cationic mordants are well known in the ink jet receptive coating
industry
for use in anchorage of anionic dye-based inks (U.S. Pat. Nos. 4,554,181,
5,474,843,
5,747,148, 5,795,425 and 5,908,723). Examples of cationic mordants are AGEFLEX
products (Ciba Specialty Chemicals). For example, Ageflex FA 1q75MC is N,N-
Dimethylaminoethyl Methacrylate Methyl Chloride Quaternary. These chemicals
are also
known to have flocculation properties when used in the paper processing
industry. Use of
cationic mordants can be mutually beneficial for anchorage of anionic dye-
based inks to
the paper base along with potential flocculation of the pigment present in the
black ink to
aid in surface hold out. Formulations produced with various mordants result in
improvements in pigment hold out on the surface.
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[00108] Issues with pigment anchorage to the surface of the paper were seen
with
formulations containing mordants. A small percentage of PVOH was added as a co-
binder to aid in overall anchorage of the ink to the paper substrate. The
resulting
optimized Formulation J, depicted in Table 10 exhibited improved pigment-black
ink hold
out without diminishing the visual integrity of the dye-based inks.
Table 10
Formulation J
Polydextrose 9.1%
Triton X-100 1.2%
Cab-O-Sperce PG001O 18.2%
Proxel GXL 0.2%
deionized water 63.1%
Ageflex FA1Q75MC 4.8%
Celvo1125"~' 3.0%
Foarnaster 111 *** 0.4%
t: available from Celanese
***: available from Cognis
[00109] Physical and optical properties were assessed on paper coated with
Formulation J alongside two commercially available ink jet printable papers
(Great White
86000 Ink Jet and Hewlett-Packard HPK115R Color Ink Jet papers). Curl (ASTM D
4825), blocking (ASTM D 918), and smoothness (TAPPI T-538) were evaluated on
the
three papers. Results are listed in Table 11.
36
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
Table 11
Physical Property Assessment
Great
J HI' Color
White
Curl (mm) 6 8 4
Blocking none none none
Sheffield 136 124 109
Smoothness (cc/min)
[00110] The ink receptive layer can absorb water in the air and swell in an
environment of high relative humidity, causing curling. For the present
invention, curl was
seen to be in the machine direction of the paper in all cases. None of the
three papers
studied exhibited any inter-sheet adhesion (i.e. blocking) when tested under
0.5 pounds
per square inch at 140 F, 75% relative humidity for 21 hours. Sheffield
smoothness is a
measurement of pressurized air flow over the surface under prescribed
conditions.
Overall results were comparable between the three papers with the exception of
the
smoothness of the sample coated with Formula J which can be expected to yield
an
improved ink jet printed image. Paper samples coated with Formula J showed
comparable-to-improved physical properties when compared with commercially
available
topcoated ink jet printing papers.
37
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[00111] Print quality assessments of the three papers were made based on ASTM
F
1944. Feathering, mottling/coalescence, wet/dry cockle, and image bleed were
comparatively evaluated. Results are presented in Table 12.
[00112] Rankings were assigned to each property based on severity. A ranking
of 1
correlates to the effect not evidenced or low severity whereas a ranking of 3
correlates to
severe visual evidence of the effect. A more detailed effect-by-effect
assignment of
rankings can be found in the ASTM F 1944 procedure.
Table 12
Print Quality Assessment Rankings
J Great HP Color
White
feathering 2 2 2
mottling/coalescence 3 1 2
wet/dry cockle 3 1 2
image bleed 2 1 1
banding 1 2 2
bronzing 3 1 1
skew 1 1 1
artifacts 1 1 1
overall rank 2 1 2
38
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
[00113] Assessments made from laboratory produced material can not correlate
well with precision manufactured ink jet coated papers such as the Great White
and HP
papers. By their very nature laboratory applied coatings exhibit lesser levels
of coating
consistency than commercially coated papers. Issues deemed severe such as
mottling/coalescence and wet/dry cockle as noted in the results would be
improved by
more precise and controlled coating of Formulation J to a base paper.
[0100] Print quality assessment testing of paper coated with Formulation J
showed
issues relating to mottling/coalescence and wet/dry cockle that are likely due
to coating
technique.
[0101] Commercial, production scale application of Formulation J would
eliminate these issues.
[0102] Optical testing of printed Formulation J coated paper shows improved
chroma values for all colors evaluated with two different types of dye-based
ink. To
measure the effect of polydextrose on the ink color development, chroma
evaluations were
performed on the various colors printed on the three papers. Chroma is
generally referred
to as color purity. Higher chroma values correlate to higher purity in color,
a richer or
denser color rendition. The three papers were printed with the HP DeskJet 6122
printer as
aforementioned and chroma evaluated. Results are found in Table 13.
39
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
Table 13
Chroma Data for Various Printed Colors
Great
J HP Color
White
RED 54.24 41.15 44.30
CYAN 55.27 46.11 47.41
BLACK 2.50 0.86 1.48
ORANGE 54.81 41.17 43.58
BLUE 45.12 33.98 35.68
MAGENTA 60.80 49.59 51.53
YELLOW 79.52 65.57 66.79
GREEN 59.83 46.61 48.17
[0103] Chroma measurements were highest for all colors with Formulation J
coated paper. This is directly related to polydextrose presence in the
formulation. To
verify these results, an Epson Color Stylus C44UX printer was used to print
the same test
pattern. All inks used in the C44UX printer are purely dye-based. Results are
found in
Table 14.
CA 02589934 2007-06-06
WO 2006/063096 PCT/US2005/044344
Table 14
Chroma Data from Epson Printer
Great
J White BP Color
RED 52.06 48.95 49.40
CYAN 32.84 33.73 36.19
BLACK 2.98 2.68 2.58
ORANGE 54.38 48.76 50.28
BLUE 44.28 36.26 37.42
MAGENTA 62.04 54.88 55.52
YELLOW 66.71 56.34 57.42
GREEN 56.93 41.84 43.27
[0104] The values obtained confirmed the trend of higher chroma with a topcoat
incorporating polydextrose as a binder. Chroma values for the test prints
ranged from
comparable to significantly improved versus those seen with the two standard
commercially available ink jet papers.
[0105] While certain preferred and alternative embodiments of the invention
have
been set forth for purposes of disclosing the invention, modification to the
disclosed
embodiments can occur to those who are skilled in the art. Accordingly, the
appended
claims are intended to cover all embodiments of the invention and
modifications thereof,
which do not depart from the spirit and scope of the invention.
41
