Note: Descriptions are shown in the official language in which they were submitted.
~ CA 02213637 1997-08-22
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An Ink Jet Recording Medium
Field of The Invention
This invention relates to ink jet recording media,
and more particularly to ink sorptive coatings that can
be used in combination with a suitable substrate to
provide an ink jet recording media.
Backqround of The Invention
Recently, ink jet printing technology has been used
for presentation, graphic arts, engineering drawing and
home office applications. The performance requirements
for ink jet recording media used for these applications
are quite stringent. The media should provide fast
drying, good color fidelity, high image resolution, and
archivability. For transparency applications, curl
performance on various commercial projectors is also
important. There are many commercial products and
proposed designs available in the field. Among them,
oxazoline based polymeric ink sorptive coatings have
shown promising performance, even though only a limited
amount of effort was previously expended by those
skilled in the art exploring this type of chemistry for
ink jet applications. As a result, only a limited
amount of information on this subject is available in
the prior art, or was otherwise available to the present
inventors prior to their present inventive discovery.
U.S. Patent 4,889,765 discloses an ink-receptive
coating composition comprising a polymer of 2-oxazoline,
CA 02213637 1997-08-22
preferably polyethyl oxazoline, and an olefin copolymer
containing pendant acid groups which are substantially
neutralized by a base. U.S. Patent 5,389,723 discloses
coatings formed from semi-interpenetrating polymeric
networks comprising a blend of a polymeric matrix
component, a liquid absorbent component, and a poly-
functional aziridine crosslinking agent for forming
water durable networks. A polyethyl oxazoline is
mentioned as a possible liquid absorbent material.
U.S. Patent 4,956,230 discloses coatings containing (1)
a hydrophilic polymer containing a carbonylamido group
and (2) a hydrophobic polymer without acidic, hydroxyl,
=NH and -NH2 functional groups.
The above designs differ from the design of the
recording media of the present invention, and the ink
sorptive coatings used therein, in both concept and
compositions. For example, the present inventive design
does not require acidic functional groups containing
polyolefin copolymers and aziridine crosslinking agents.
Instead, in the present invention, hydrogels are formed
through inherent physical and chemical interactions.
Furthermore, we have found that the present inventive
design provides optimal performance by using acidic,
hydroxyl, =NH and -NH2 functional groups, especially
hydroxyl groups, in the inventive polyalkyl- or
polyphenyl- oxazoline based ink sorptive coatings of the
present invention. That is, we have discovered that
such functional groups can be helpful in designing ink
jet media containing alkyl and phenyl oxazoline based
polymeric ink sorptive coatings.
Summary of The Invention
We have designed an ink sorptive coating that can
be used for ink jet recording media (e.g., ink jet
recording paper, ink jet recording film and other
substrate based ink jet recording products). The ink
sorptive coating can be used to provide ink jet
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recording media having improved performance for ink jet
recording applications.
Accordingly, an object of the present invention is
to provide an ink sorptive coating that can be used for
ink jet recording media. Another object of the present
invention is to provide an ink jet recording media,
wherein an ink sorptive coating is applied to the
surface of a suitable substrate, and wherein the coating
provides improved image quality, curl performance and
dry time to the prepared media.
The good performance properties of the ink sorptive
coatings and recording media of the present invention
are believed to result from the fact that the ink
sorptive coatings of the present invention, comprise:
(1) a polyalkyl oxazoline polymer, a polyphenyl
oxazoline polymer, a copolymer containing a polyalkyl
oxazoline monomer unit, a copolymer containing a
polyphenyl oxazoline monomer unit, or a copolymer
containing a polyalkyl oxazoline monomer unit and a
polyphenyl oxazoline monomer unit; and
(2) a hydroxyl (-OH) group containing polymer or
copolymer.
Optionally, a surface coating layer containing a
cellulose ether may be employed over the ink sorptive
coatings of the inventive media in order to achieve
desired performance properties.
Detailed Description of The Invention
The following detailed description is provided as
an aid to those desiring to practice the present
invention. However, it is not to be construed as being
unduly limiting to the present inventive discovery,
since those of ordinary skill in the art will readily
recognize that the various inventive embodiments
disclosed herein may be modified using standard
techniques and materials known in the art, without
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departing from the spirit or scope of the present
inventive discovery.
The ink jet recording medium of the present
invention contains a substrate having on a surface
thereof at least one ink sorptive coating layer that
comprises:
(1) a polyalkyl oxazoline polymer, a polyphenyl
oxazoline polymer, a copolymer containing a polyalkyl
oxazoline monomer unit, a copolymer containing a
polyphenyl oxazoline monomer unit, or a copolymer
containing a polyalkyl oxazoline monomer unit and a
polyphenyl oxazoline monomer unit; and (2) a hydroxyl
group (-OH) containing polymer or copolymer.
Typical examples of polyalkyl oxazoline and
polyphenyl oxazoline monomer units that are useful in
preparing the ink sorptive coatings and ink jet
recording media of the present invention are polymethyl
oxazoline, polyethyl oxazoline, polypropyl oxazoline,
polyphenyl oxazoline, and the like. Both, polymers and
copolymers containing such monomer units are useful in
preparing the ink sorptive coatings and ink jet
recording media of the present invention. Preferably,
the weight average molecular weight of such polymers and
copolymers should be greater than about 40,000 and more
preferably greater than about 200,000.
Typical examples of the hydroxyl group (-OH)
containing polymers and copolymers that are useful in
preparing the ink sorptive coatings and ink jet
recording media of the present invention are those that
contain a cellulose acetate butyrate monomer unit, a
cellulose acetate propionate monomer unit, a poly(vinyl
butyral) monomer unit, a ethylcellulose monomer unit, a
partially hydrolyzed poly(vinyl acetate) monomer unit,
a nitrocellulose monomer unit, a hydroxyethyl
methacrylate monomer unit, and the like. Preferably,
the weight average molecular weight of such polymers and
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copolymers should be greater than about 25,000 and more
preferably greater than about 100,000.
The ink sorptive coating(s) of the present
invention preferably contain about 50~ to about 98~ of
the polyalkyl oxazoline and/or polyphenyl oxazoline
containing polymer(s) or copolymer(s) therein, on a
weight/weight basis; more preferably about 80% to about
95~, on a weight/weight basis.
For some applications, a surface coating over said
ink sorptive coating layer(s) is required. In such an
instance, the ink sorptive coating(s) are coated
directly on the base substrate and then dried. The
surface coating layer is then applied on top of the ink
sorptive coating layer(s), with the surface coating
layer containing at least one cellulose ether.
Typical examples of cellulose ethers that may be
used in the surface coatings of the present invention
are methyl cellulose, hydroxyethyl cellulose,
hydroxypropyl cellulose, hydroxypropyl ethyl cellulose,
hydroxypropyl methyl cellulose, hydroxyethyl methyl
cellulose and carboxymethyl cellulose.
The ink sorptive coatings of the present invention
should have a glass transition temperature, Tg, that is
greater than about 40~C, and preferably that is greater
than about 60~C. (When the Tg is not attainable, the
softening temperature is used.) When the Tg is below
about 40~C, the coatings are too tacky for commercial
applications.
Glass transition temperature is measured on a
Differential Scanning Calorimeter (TA Instruments, Model
DC 2910), calibrated with appropriate standards. The
reading and baseline errors from running replicate DSC
experiments leads to a typical accuracy in measuring the
Tg of about 3~C. Measurements of heat flow versus
temperature are made upon heating in the range of about
5~ to 200~C at a heating rate of 20~C/minute. The
sample chamber is purged with nitrogen. Film-like
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samples are encapsulated in an aluminum pan. The
midpoint method is used to obtain the glass transition
temperature of the polymer blend from the measured DSC
curve of heat flow versus temperature.
The thickness of the inventive ink sorptive
coatings of the present invention is not particularly
restricted, but is generally governed by application of
each ink sorptive coating layer to the substrate in an
amount of from about 2 grams per square meter to about
30 grams per square meter.
The ink sorptive coatings disclosed in this
invention can be applied to various base substrates in
order to provide one of the present inventive ink jet
recording media. For example, suitable substrates for
such purposes include transparent plastics, translucent
plastics, matte plastics, opaque plastics, papers and
the like. Suitable polymeric materials for use as the
base substrate include polyester, cellulose esters,
polystyrene, polypropylene, poly(vinyl acetate),
polycarbonate, and the like. Poly(ethylene
terephthalate) film is a particularly preferred base
substrate. Further, while almost any paper can be used
as the base substrate, clay coated papers and polyolefin
coated papers are particularly preferred as base
substrate papers. The thickness of the base substrate
is not particularly restricted but should generally be
in the range of from about 1 to about 10 mils,
preferably from about 3.0 to about 5.0 mils. The base
substrate may be pretreated to enhance adhesion of the
ink sorptive coating thereto, if so desired.
According to a preferred embodiment of the
invention, the ink sorptive coatings of the present
invention may further comprise about 0.1 to about 15~ by
weight of a particulate(s) based on the weight of the
dry coating. Suitable particulates that can be used in
the ink sorptive coating(s) to modify their surface
properties include inorganic particulates such as
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,
silica, alumina, kaolin, glass beads, calcium carbonate
and titanium oxide, and organic particulate such as
polyolefins, polystyrene, polyurethane, starch,
poly(methyl methacrylate) and polytetrafluoroethylene.
Such particulates may also be used in the optional
surface coating layers that may be used in the inventive
media, if so desired. In such an instance, the
particulate(s) may be present in the optional surface
coating layers in an amount of about 0.1 to about 15~ by
weight, based on the weight of the dry coatings.
In practice, various additives may also be employed
in the ink sorptive coatings of the present invention,
as well as in the optional surface coatings of the
present invention. These additives can include surface
active agents which control the wetting or spreading
action of coating solutions, antistatic agents,
suspending agents, and acidic compounds to control pH of
the coatings. Other additives may also be used, if so
desired.
The surface of the base substrate which does not
bear the ink sorptive coating may have a backing
material placed thereon in order to reduce electrostatic
charge and to reduce sheet-to-sheet friction and
sticking, if so desired. The backing material may
either be a polymeric coating, a polymer film or a paper
backing material.
Any of a number of coating methods may be employed
to coat the ink sorptive coating(s) onto a suitable
substrate. For example, roller coating, blade coating,
wire-bar coating, dip coating, extrusion coating, air
knife coating, curtain coating, slide coating, doctor
coating or gravure coating, may be used and are well
known in the art. Such coating methods may also be used
to coat the optional surface coating layers on the
inventive ink jet recording media, if so desired.
The following Examples are given merely as
illustrative of the invention and are not to be
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considered as limiting. In the following examples,
parts are given as parts by weight, based on solid
content.
Example I
A coating composition is prepared according to the
following formulation:
Ink Sorptive Coatinq:
Poly (2-ethyl-2-oxazoline)1 85 parts
Poly vinylbutyral2 15 parts
Methyl Ethyl Ketone 280 parts
Propylene Glycol Monomethyl Ether120 parts
Poly(methyl methacrylate) beads31 part
1. Manufactured by PCI, Inc.
2. Manufactured by Monsanto Company
3. Manufactured by Soken Chemical & Engineering
Company, Ltd.
The coating is applied to a polyester film (ICI
Films) using a No. 42 Meyer rod. The ink sorptive
coating is dried at about 130~C for about 4 minutes.
Example II
A coating composition is prepared according to the
following formulation:
Ink Sorptive Coatinq:
Poly (2-ethyl-2-oxazoline) 85 parts
Copolymer A1 15 parts
Methyl Ethyl Ketone 280 parts
Propylene Glycol Monomethyl Ether120 parts
Poly(methyl methacrylate) beads1 part
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1. A Copolymer of methyl methacrylate and hydroxyethyl
methacrylate, manufactured by Allied Colloids Inc.
The coating is applied to a polyester film (ICI
Films) using a No. 42 Meyer rod. The ink sorptive
coating is dried at about 130~C for about 4 minutes.
Example III
A coating composition is prepared according to the
following formulation:
Ink SorPtive Coating:
Poly (2-ethyl-2-oxazoline)-co-
(2-phenyl-2-oxazoline)l 85 parts
Copolymer A 15 parts
Methyl Ethyl Ketone 280 parts
Propylene Glycol Monomethyl Ether120 parts
Poly(methyl methacrylate) beads1 part
1. Manufactured by PCI, Inc.
The coating is applied to a polyester film (ICI
Films) using a No. 42 Meyer rod. The ink sorptive
coating is dried at about 130~C for about 4 minutes. A
surface coating layer is then coated over the ink
sorptive coating according to the following formulation:
Surface Coating Layer
Hydroxypropyl Methyl Cellulose1 1 part
Water 99 parts
1. Manufactured by Dow Chemical Company
The surface coating layer is applied with a No. 8
Meyer rod and is dried at about 130~C for about 2
minutes.
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Example IV
The ink sorptive coating of Example I is applied to
polyester film (ICI Films) using a No. 42 rod and dried
for about 4 minutes at about 130~C. The surface coating
layer of Example III is then coated over the ink
sorptive coating. The surface coating layer is applied
with a No. 8 Meyer rod and is dried at about 130~C for
about 2 minutes.
Comparative Example I
A coating composition is prepared according to the
following formulation:
Ink Sorptive Coatinq:
Poly (2-ethyl-2-oxazoline) 85 parts
Polyurethane1 15 parts
Methyl Ethyl Ketone 280 parts
Propylene Glycol Monomethyl Ether120 parts
Poly(methyl methacrylate) beads1 part
1. Manufactured by B.F. Goodrich, Inc.
The coating is applied to a polyester film (ICI
Films) using a No. 42 Meyer rod. The ink sorptive
coating is dried at 130~C for about 4 minutes.
Comparative Example II
A coating composition is prepared according to the
following formulation:
Ink Sorptive Coatinq:
PVP K-901 85 parts
Copolymer A 15 parts
Methyl Ethyl Ketone 280 parts
Propylene Monomethyl Ether 120 parts
Poly(methyl methacrylate) beads1 part
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1. Poly (vinylpyrrolidone), manufactured by ISP
Corporation
The coating is applied to a polyester film (ICI
Films) using a No. 42 Meyer rod. The ink sorptive
coating is dried at 130~C for about 4 minutes.
The prepared ink jet recording media are evaluated
for performance on a HEWLETT PACKARD DESKJET 850C
printer with the ink jet pens supplied by HEWLETT
PACKARD for the DESKJET 850C printer.
The dry time of each example is measured by
initially printing a test plot onto each ink jet
recording medium example. The printed sheet is then
placed on top of a 20 lb. ream of XEROX 4200 paper.
This is taken as time zero (to)~ At one minute intervals
a sheet of white bond paper is placed onto the surface
of the print. Another 20 lb. ream of XEROX 4200 paper
is placed on top of the white bond paper. After five
seconds the top ream of paper and white bond paper is
removed from on top of the print. The print is dry when
no transfer of ink between the example and the white
bond paper has occurred, which is termed the dry time
( tdry) -
The projector curl performance is conducted on a
POLAROID overhead projector. The projector platen
surface is allowed to warm up to 40~C. The ink jet
recording medium is placed onto the platen surface for
one minute. After one minute the distance that each of
the corners of the ink jet recording medium has raised
from the platen surface is measured. The highest
measured distance is the projector curl of the ink jet
recording medium. It is the inventors' experience that
the ink jet recording media will give defocused images
or low image resolution when their projector curl is
greater than about 10 mm.
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The black image optical density or KOD is measured
on a MACBETH TD904 (Macbeth Process Measurements). A
reading is taken at four different locations along a
solid black image strip. The average of the four
readings is the black image optical density.
The glass transition temperature, dry time,
projector curl and black image optical density of each
example and comparative example are provided in Table I,
below.
Table I
The Performance Comparison of Ink Jet Recording Media
Example Glass Dry Time Projec Black
Transition (minutes) tor Image
Temperature Curl Optical
(Tg, ~C) (mm) Density
(KOD)
I 56 2.5 3 .80
II 57 2.5 2 .88
III 57 3 4 1.39
IV 60 ~4 5 1.03
CI 50 >4 0 .42
CII 156 >4 54 1.43
As shown in Table I, each of the inventive Examples
I-IV exhibited an improved combination of properties
when compared with the Comparative Examples C-I and C-
II. This is evident from their performances in curl,
dry time and optical density.
For example, the inventive media of Examples I-IV
possess good black image optical densities. This is
important, since good performance in this test is an
indicator of a low amount of pigment ink cracking.
Specifically, the lower the optical density, the higher
the degree of cracking.
Notably, the ink jet recording media of the present
invention possess an improved optical density without
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experiencing a deterioration in other properties such
as curl. In this regard, Table I clearly shows that the
ink jet recording media of the present invention
possesses good projector curl performance properties
(i.e, much less than 10 mm of curl).
Additionally, the ink jet recording media of the
present invention possesses the advantage of an improved
dry time, which can allow for a higher throughput in ink
jet printing devices.
Each of the patents referred to herein is
incorporated by reference herein in its entirety.
