U.S. patent application number 12/127750 was filed with the patent office on 2008-09-25 for pigmented ink composition.
Invention is credited to Takahiro FURUTANI, Nagayuki TAKAO.
Application Number | 20080234428 12/127750 |
Document ID | / |
Family ID | 29996566 |
Filed Date | 2008-09-25 |
United States Patent
Application |
20080234428 |
Kind Code |
A1 |
FURUTANI; Takahiro ; et
al. |
September 25, 2008 |
PIGMENTED INK COMPOSITION
Abstract
A pigmented ink composition comprising a pigment, a resin having
an acidic group and an organic solvent having a boiling point of at
least 150.degree. C. which is present in an amount of from 50 to
90% by weight based on the whole weight of the ink composition.
When this ink composition is subjected to an printed layer-sliding
test in which the ink composition is applied on a cationically
treated printing medium with a #4 bar coater (available from TOYO
SEIKI KOGYO CO., LTD.) and dried and then the printed surface is
slid with a cloth on which a weight of 50 g is placed, the printed
record is not grazed. This ink composition contains the pigment
with a small dispersion particle size and has good water
resistance, can be printed on a plain paper sheet without cockling,
and suffers from no grazing of printed records when the ink
composition is printed on a cationically treated paper sheet.
Inventors: |
FURUTANI; Takahiro; (Osaka,
JP) ; TAKAO; Nagayuki; (Muko-shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
29996566 |
Appl. No.: |
12/127750 |
Filed: |
May 27, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10518452 |
Dec 20, 2004 |
7393884 |
|
|
PCT/JP2003/007840 |
Jun 20, 2003 |
|
|
|
12127750 |
|
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Current U.S.
Class: |
524/599 ;
524/612 |
Current CPC
Class: |
C09D 11/36 20130101;
C09D 11/322 20130101 |
Class at
Publication: |
524/599 ;
524/612 |
International
Class: |
C08G 63/60 20060101
C08G063/60 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2002 |
JP |
P2002-179470 |
Claims
1. A pigmented ink composition comprising a pigment, a resin and an
organic solvent having a boiling point of at least 150.degree. C.
which is present in an amount of from 50 to 90% by weight based on
the whole weight of the ink composition; wherein said resin has an
ether bond and an acid value of 10 to 300 mg-KOH/g.
2. The pigmented ink composition according to claim 1 which
comprises 0.1 to 20% by weight of the pigment and 0.5 to 30% by
weight of the resin based on the whole weight of the ink
composition.
3. The pigmented ink composition according to claim 1, wherein said
resin has a weight average molecular weight of 1.times.10.sup.4 to
3.times.10.sup.5, and a molecular weight distribution of 1.5 to
10.
4. The pigmented ink composition according to claim 1, wherein said
resin is a water-insoluble resin having a hydrophobic group.
5. The pigmented ink composition according to claim 1, wherein said
resin is an acrylic resin.
6. The pigmented ink composition according to claim 1, wherein said
organic solvent having a boiling point of at least 150.degree. C.
is a polar solvent.
7. The pigmented ink composition according to claim 1, wherein said
organic solvent having a boiling point of at least 150.degree. C.
is an ether solvent.
8. The pigmented ink composition according to claim 1, wherein said
organic solvent having a boiling point of at least 150.degree. C.
is at least one compound selected from the group consisting of
ethylene glycol monoalkyl ether monoalkyl ester, diethylene glycol
monoalkyl ether monoalkyl ester, triethylene glycol monoalkyl ether
monoalkyl ester, propylene glycol monoalkyl ether monoalkyl ester,
dipropylene glycol monoalkyl ether monoalkyl ester, tripropylene
glycol monoalkyl ether monoalkyl ester, ethylene glycol dialkyl
ester, diethylene glycol dialkyl ester, triethylene glycol dialkyl
ester, propyleneglycol dialkyl ester, dipropylene glycol dialkyl
ester and tripropylene glycol dialkyl ester.
9. The pigmented ink composition according to claim 1, which is
used in an ink-jet printer, wherein said ink composition has a
surface tension of at least 25 mN/m at 20.degree. C. and a
viscosity of 2 to 30 cp at 20.degree. C., and the pigment has a
dispersion average particle size of 0.01 to 0.5 .mu.m.
Description
[0001] This application is a Divisional of co-pending application
Ser. No. 10/518,452 filed on Dec. 20, 2004, and for which priority
is claimed under 35 U.S.C. .sctn. 120. Application Ser. No.
10/518,452 is the national phase of PCT International Application
No. PCT/JP2003/007840 filed on Jun. 20, 2003 under 35 U.S.C. .sctn.
371. The entire contents of each of the above-identified
applications are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a pigmented ink composition
comprising a pigment, a resin, and an organic solvent. In
particular, the present invention relates to a pigmented ink
composition for ink-jet printing systems.
BACKGROUND ART
[0003] In an ink-jet printing system, a liquid ink is ejected from
a nozzle towards a printing medium using a pressure, heat or an
electric field as a driving source to print the printing medium.
The ink-jet printing system can be used with a low running cost and
form high quality images. Accordingly, in these years, the ink-jet
printing system has been quickly spreading not only as an office
printing system but also domestic printing system.
[0004] As inks for ink-jet printing, aqueous dye inks, which
comprise water-soluble dyes dissolved in aqueous media, are used
since they have high coloring properties and cause less clogging of
printer head orifices. However, the aqueous dye inks have some
drawbacks such as low water-resistance, insufficient durability,
etc.
[0005] Recently, large-size ink-jet printers, which can accommodate
to the A-0 size sheet, have been developed and increasingly used
outdoor applications for printing exterior posters. In addition,
with the popularization of digital cameras, the ink-jet printing is
used in applications where printed materials are stored for a long
time. Under such circumstances, pigmented inks with good water
resistance and weather resistance are being vigorously
developed.
[0006] However, the aqueous pigment inks comprising water or an
aqueous medium as a solvent are not suitable for printing posters
since plain paper sheets are cockled (i.e. waving after drying)
when they are printed with such aqueous pigment inks.
[0007] Oil-based pigmented inks comprising aliphatic hydrocarbons
or alcohols as solvents (for example, inks disclosed in
JP-A-2000-38533, JP-A-2001-220527 and JP-A-2001-329193) cause less
cockling. However, when they are printed on a cationically treated
printing media (in general, gloss paper sheets), printed records
tend to be grazed. For example, if a number of sheets are
continuously printed, the printed records are easily grazed, when
the second and subsequent printed sheets are laminated on the
previous sheet for several seconds, or the printed records are
touched with a hand after printing.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is to provide a pigmented
ink composition having good anti-grazing properties, in particular,
a pigmented ink composition for ink-jet printers, which contains a
pigment with a small dispersion particle size and has good water
resistance, can be printed on a plain paper sheet without cockling,
and suffers from no grazing of printed records when the ink
composition is printed on a cationically treated paper sheet.
[0009] It has been found that when a pigmented ink composition
contains a specific resin and a specific organic solvent in a
specified amount, the pigment has a small dispersion particle size,
and the ink composition has good water resistance, it can be
printed on a plain paper sheet without cockling and furthermore it
has good anti-grazing properties such that it suffers from no
grazing of printed records when it is printed on a cationically
treated paper sheet.
[0010] The present invention has been completed based on the above
finding.
[0011] Accordingly, the present invention provides a pigmented ink
composition comprising a pigment, a resin having an acidic group
and an organic solvent having a boiling point of at least
150.degree. C. which is present in an amount of from 50 to 90% by
weight based on the whole weight of the ink composition.
[0012] With the pigmented ink composition of the present invention,
when the ink composition is subjected to an printed layer-sliding
test in which the ink composition is applied on a cationically
treated printing medium with a #4 bar coater (available from TOYO
SEIKI KOGYO CO., LTD.) and dried and then the printed surface is
slid with a cloth on which a weight of 50 g is placed, the printed
record is not grazed, that is, the printed record has good
anti-grazing properties.
[0013] In concrete, the printed layer-sliding test is carried out
as follows:
[0014] A pigmented ink composition is applied on a cationically
treated printing medium with a #4 bar coater (available from TOYO
SEIKI KOGYO CO., LTD.) and dried for 10 minutes in an atmosphere
kept at a temperature of 20 to 25.degree. C. and a humidity of 40
to 60%, and then the printed layer of the ink composition is slid
ten times with a cloth, on which a weight of 50 g (a contact area
of 3.1 cm.sup.2) is placed at an interval of 3 seconds. Then, the
grazing of the printed layer is evaluated.
[0015] An example of a cationically treated printing medium is a
gloss paper sheet for ink-jet printing with aqueous dyes. Gloss
paper sheets are commercially available from Hitachi Maxell, Epson,
Canon, Konica Minolta, etc.
[0016] The ink composition is preferably applied with a #4 coater
to a thickness of 5 to 10 .mu.m, and the thickness of the printed
layer after being dried for 10 minutes is preferably from 0.09 to
1.8 .mu.m.
[0017] Examples of the cloth to be slid on the coating layer of the
ink composition include BEMCOTTON, TECHNICLUE, KIM WIPE, KIM WIPER,
CHEM DRY, KIM TEC, KIM TECS, KIM TOWEL (all available from ASONE),
cloths of natural fibers such as silk, cotton, etc., cloths of
synthetic fibers such as polyester fiber, etc.
[0018] The pigmented ink composition of the present invention can
withstand the above printed layer-sliding test. That is, the
coating layer is not grazed in the sliding layer-sliding test and
has good anti-grazing properties. Therefore, when the pigmented ink
composition of the present invention is printed on a cationically
treated printing medium with an ink jet printer, the anti-grazing
properties of the printed material or record are greatly improved.
For example, when the second and subsequent printed sheets are
laminated on the previous sheet for several seconds, or the printed
records are touched with a hand after printing, the printed records
are not grazed.
DETAILED DESCRIPTION OF THE INVENTION
[0019] In the present invention, the pigment may be an inorganic
pigment, an organic pigment or a dye.
[0020] Examples of the inorganic pigment include carbon black,
titanium oxide, Chinese white (zinc flower), zinc oxide, lithopone,
iron oxide, aluminum oxide, silicon dioxide, kaolinite,
montmorillonite, talc, barium sulfate, calcium carbonate, silica,
alumina, cadmium red, red oxide, molybdenum red, chrome vermilion,
molybdate orange, chrome yellow, cadmium yellow, yellow iron oxide,
titanium yellow, chromium oxide, viridian, cobalt green, titanium
cobalt green, cobalt chrome green, Armenian blue, ultramarine blue
pigment, Paris blue, cobalt blue, cerulean blue, manganese violet,
cobalt violet, mica, etc.
[0021] Examples of the organic pigment include azo pigments,
azomethine pigments, polyazo pigments, phthalocyanine pigments,
quinacridone pigments, anthraquinone pigments, indigo pigments,
thioindigo pigments, quinophthalone pigments, benzimidazolone
pigments, isoindoline pigments, isoindolinone pigments, etc.
[0022] Examples of the dye include azo dyes, anthraquinone dyes,
indigo dyes, phthalocyanine dyes, carbonyl dyes, guinonimine dyes,
methine dyes, quinoline dyes, nitro dyes, etc. Among them, disperse
dyes are particularly preferred.
[0023] The amount of the pigment is preferably from 0.1 to 20% by
weight based on the whole weight of the ink composition. When the
amount of the pigment is less than 0.1% by weight, the properties
of the pigment may not be sufficiently exerted. When the amount of
the pigment exceeds 20% by weight, the stability of the dispersion
or the anti-grazing properties of the printed records may not be
sufficiently improved.
[0024] In the present invention, the resins having the acidic group
include a wide variety of resins such as acrylic, polyester,
polyurethane, epoxy and amino resins having an acidic group such as
a carboxyl group, a sulfonic acid group, a phosphonic acid group,
etc. These resins may be used independently or as a mixture of two
or more of them. Among them, the acrylic resins are preferable in
view of the easiness of synthesis and grafting, and the easiness of
the introduction of the acidic group. Furthermore, the resin having
the acidic group is used as a dispersant of the pigment or as a
resin other than a dispersant. In such a case, the resin having the
acidic group may be used in combination with a common dispersant
and/or an additional resin.
[0025] The resin having the acidic group not only improves the
dispersion particle size of the pigment or the water resistance of
the ink composition but also has good effects on the anti-grazing
properties of the printed records printed on the cationically
treated printing media. With the gloss papers for ink-jet printing
of aqueous dyes, an ink-receptive layer is designed to be cationic
to increase the fixing and water resistance of anionic dyes. For
example, cationic resins or cationic alumina fillers are used to
make the gloss papers cationic. When the anionic resin having the
acidic group is used, the adhesion of the resin to the cationic
ink-receptive layer is enhanced so that the anti-grazing properties
of the printed records are improved.
[0026] According to the present invention, the resin having the
acidic group preferably has an acid value of 10 to 300 mg-KOH/g,
more preferably from 15 to 200 mg-KOH/g, most preferably 30 to 150
mg-KOH/g. When the acid value is less than 10 mg-KOH/g, the above
effects of the present invention may not be satisfactorily
achieved. When the acid value exceeds 300 mg-KOH/g, the improvement
of the above effects may saturate, and in some cases, the viscosity
of the ink composition may increase.
[0027] The resin having the acidic group preferably has a weight
average molecular weight of 1.times.10.sup.4 to 3.times.10.sup.5,
more preferably from 2.times.10.sup.4 to 1.times.10.sup.5. When the
weight average molecular weight of the resin is less than
1.times.10.sup.4, it is too small so that the printed records
having sufficient strength may not be formed. When the weight
average molecular weight of the resin exceeds 3.times.10.sup.5, the
viscosity of the ink composition tends to increase. Furthermore,
the resin having the acidic group preferably has a molecular weight
distribution of 1.5 to 10, in particular 2 to 5. When the resin
having the acidic group has an adequate molecular weight
distribution, the printed records formed from the ink composition
of the present invention exhibits the sufficient anti-grazing
properties in the wide range of circumstances where the printed
materials are used.
[0028] Herein, the weight average molecular weight of the resin
having the acidic group means a polystyrene-converted molecular
weight measured by gel permeation chromatography.
[0029] According to the present invention, the resin having the
acidic group is preferably a resin having an ether bond. When the
resin has the ether bond, it has improved affinity with the
cationically treated printing media and thus the anti-grazing
properties of the printed records can be further improved.
Alternatively, the resin is preferably a water-insoluble resin
having a hydrophobic group, since the water resistance of the
printed records is further improved due to the insolubility of the
resin having the hydrophobic group in water. Furthermore, the resin
preferably has a polar group such as a hydroxyl group or an amino
group. When the resin has the polar group, it has better affinity
to the organic solvent or the paper sheet to be printed.
[0030] The above resin used in the present invention may be easily
synthesized by copolymerizing a monomer having an acidic group
(hereinafter referred to as "anionic monomer"), a monomer having an
ether bond, a monomer having a hydrophobic monomer and optionally a
monomer having a polar group by a conventional polymerization
method. Copolymer resins comprising those monomers are commercially
available.
[0031] Examples of the anionic monomer include monomers having a
carboxyl group such as acrylic acid, methacrylic acid, crotonic
acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid,
itaconic acid, fumaric acid, acryloyloxyethyl phthalate,
acryloyloxyethyl succinate, 2-methacryloyloxyethylsuccinic acid,
2-methacryloyloxyethyl-hexahydrophthalic acid,
2-acryloyloxyethylsuccinic acid, 2-acryloyloxyethylphthalic acid,
etc.; monomers having a sulfonic acid group such as 2-sulfonylethyl
acrylate, 2-sulfonylethyl methacrylate, butylacrylamidesulfonic
acid, etc.; and monomers having a phosphonic acid group such as
2-phosphonylethyl methacrylate, 2-phosphonylethyl acrylate, etc.
Among them, the monomers having a carboxyl group are
preferable.
[0032] Preferable examples of the monomers having an ether bond
include monomers known as polyether-based acromonomers such as
"PME-200", "PME-400", "PME-1000", "AME-400", "PP-500", "PP-800",
"PP-1000" and "PE-350" (all available from NOF Corporation); and
"AMP-10G" and "MP-60G" (both available from Shin-Nakamura Chemical
Co., Ltd.).
[0033] Examples of the monomers having a hydrophobic group include
acrylates and methacrylate such as methyl acrylate, ethyl acrylate,
isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, tert-butyl
acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate,
isopropyl methacrylate, n-propyl methacrylate, n-butyl
methacrylate, isobutyl methacrylate, tert butyl methacrylate,
tridecyl methacrylate, benzyl methacrylate, 2-ethylhexyl acrylate,
2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate,
lauryl acrylate, lauryl methacrylate, cetyl acrylate, cetyl
methacrylate, stearyl acrylate, stearyl methacrylate, behenyl
acrylate, behenyl methacrylate, etc.; styrene monomers such as
styrene, .alpha.-methylstyrene, o-methylstyrene, m-methylstyrene,
p-methylstyrene, p-tert-butylstyrene, etc.; itaconates such as
benzyl itaconate, etc.; maleates such as dimethyl maleate, etc.;
fumarates such as dimethyl fumarate, etc.; vinyl acetate; and the
like.
[0034] Examples of the monomers having a polar group include
monomers having a hydroxyl group such as 2-hydroxyethyl acrylate,
2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl
methacrylate, etc.; monomers having a primary amino group such as
aminoethyl acrylate, aminopropyl acrylate, aminoethyl methacrylate,
aminoproyl methacrylate, etc.; monomers having a secondary amino
group such as methylaminoethyl acrylate, methylaminopropyl
acrylate, ethylaminoethyl acrylate, ethylaminopropyl acrylate,
methylaminoethyl methacrylate, methylaminopropyl methacrylate,
ethylaminoethyl methacrylate, ethylaminopropyl methacrylate, etc.;
monomers having a tertiary amino group such as dimethylaminoethyl
acrylate, diethylaminoethyl acrylate, dimethylaminopropyl acrylate,
diethylaminopropyl acrylate, dimethylaminoethyl methacrylate,
diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate,
diethylaminoprupyl methacrylate, etc.; monomers having an amide
group such as acrylamide, methacrylamide, dimethylacrylamide,
dimethylaminopropylacrylamide, isopropylacrylamide,
diethylacrylamide, etc.; cyclic monomers such as
acryloylmorpholine, vinylpyrrolidone, vinylpyridine, etc.; and the
like.
[0035] In the present invention, the amount of the resin having the
acidic group is preferably from 0.5 to 30% by weight, more
preferably from 1 to 20% by weight, most preferably from 1.5 to 10%
by weight, based on the whole weight of the ink composition. When
the amount of the resin is less than 0.5% by weight, the above
effects achieved by this resin may not be attained. When the amount
of the resin exceeds 30% by weight, the improvement of the effects
achieved by this resin may saturate, and the viscosity of the ink
composition tends to increase.
[0036] The amount of the resin having the acidic group based on the
weight of the pigment is preferably from 10 to 300% by weight, more
preferably from 20 to 200% by weight, most preferably from 50 to
150% by weight. When this amount is less than 10% by weight, the
proportion of the pigment is too high so that the sufficient fixing
of the ink composition may not be attained. When this amount
exceeds 300% by weight, the improvement of the effects achieved by
this resin may saturate, and the viscosity of the ink composition
tends to increase.
[0037] In the present invention, the organic solvent has a boiling
point of at least 150.degree. C. If an organic solvent having a
boiling point of lower than 150.degree. C. is used, the ink
composition is dried on the head of an ink jet printer so that the
head tends to be clogged. The organic solvent having a boiling
point of at least 150.degree. C. is preferably a polar solvent,
more preferably an ether solvent. The ether solvent has good
affinity with the cationically treated printing media and
significantly improves the anti-grazing properties of the printed
records, since it has a high polarity.
[0038] The ether solvent is preferably a monoalkyl ether monoalkyl
ester derivative or a dialkyl ester derivative of (poly)alkylene
glycol. Examples of these compounds include ethylene glycol
monoalkyl ether monoalkyl ester, diethylene glycol monoalkyl ether
monoalkyl ester, triethylene glycol nonoalkyl ether monoalkyl
ester, propylene glycolmonoalkyl ethermonoalkyl ester, dipropylene
glycol monoalkyl ethermonoalkyl ester, tripropylene glycol
monoalkyl ether monoalkyl ester, ethylene glycol dialkyl ester,
diethylene glycol dialkyl ester, triethylene glycol dialkyl ester,
propylene glycol dialkyl ester, dipropylene glycol dialkyl ester,
tripropylene glycol dialkyl ester, etc. They may be used
independently or as a mixture of two or more of them.
[0039] Specific examples of these compounds include diethylene
glycol monoethyl ether monomethyl ester, diethylene glycol
monobutyl ether monomethyl ester, dipropylene glycol monoethyl
ether monomethyl ester, diethylene glycol monobutyl ether
monomethyl ester, diethylene glycol monoethyl ether monoethyl
ester, diethylene glycol monoethyl ether monobutyl ester,
diethylene glycol dimethyl ester, triethylene glycol monoethyl
ether monomethyl ester, triethylene glycol monobutyl ether
monomethyl ester, triethylene glycol dimethyl ester, tetraethylene
glycol monoethyl ether monomethyl ester, tetraethylene glycol
monobutyl ether monomethyl ester, etc.
[0040] These compounds have at least one polar group (an ester
group and an ether group) and also at least one hydrophobic group
(an alkyl group) and thus they have a good fixing property to any
printing media and good water resistance. These two properties may
easily be adjusted by selecting the number of the polar groups and
the number of the carbon atoms in the hydrophobic group. The polar
group contributes to the prevention of cockling when the ink
composition is printed on a plain paper sheet.
[0041] The organic solvent having a boiling point of at least
150.degree. C. is used in an amount of 50 to 95% by weight,
particularly 60 to 90% by weight, based on the whole weight of the
ink composition. When the amount of the organic solvent is too
small or too large, the effects of the present invention may not be
attained. The organic solvent having a boiling point of at least
150.degree. C. may be used in combination with other common organic
solvent such as an aliphatic hydrocarbon. In this case, the total
amount of the organic solvent having a boiling point of at least
150.degree. C. and the other solvent is preferably in the above
range. The solid content in the ink composition is preferably
adjusted in a range from 0.5 to 20% by weight, particularly from
1.5 to 15% by weight by selecting the amount of the organic
solvent.
[0042] The ink composition of the present invention comprises the
pigment, the resin having the acidic group and the organic solvent
having a boiling point of at least 150.degree. C. as the essential
components. The ink composition may optionally contain common
additives such as surfactants, other resins, surface-modifiers,
leveling agents, defoaming agents, antioxidants, pH regulators,
charging agents, disinfectants, preservatives, charge-adjusters,
wetting agents, anti-skinning agents, perfumes, deodorants or
deodorizers, pigment derivatives, etc.
[0043] The pigmented ink composition of the present invention may
be prepared by mixing and dispersing the components using a
barrel-driving type mills (e.g. ball mill, centrifugal mill,
planetary mill, etc.), high-speed rotation mills (e.g. sand mill,
etc.), medium-agitation mills (e.g. agitated vessel mill, etc.),
simple dispersing equipment (e.g. disper, etc.), and the like.
[0044] The pigmented ink composition of the present invention, in
particular, one for ink-jet printing systems, preferably has a
surface tension at 20.degree. C. of at least 25 mN/m, more
preferably at least 27 mN/m, and preferably a viscosity at
20.degree. C. of 2 to 30 cp, more preferably 3 to 15 cp. When the
ink composition has a surface tension or a viscosity outside the
above range, it may not be stably printed on a printing medium.
[0045] The pigment usually has a dispersion average particle size
of 0.01 to 0.5 .mu.m, preferably 0.05 to 0.3 .mu.m, more preferably
0.06 to 0.2 .mu.m. When the average particle size of the pigment is
less than 0.01 .mu.m, the dispersion of the ink composition may
become unstable. When the average particle size of the pigment
exceeds 0.5 .mu.m, the pigment tends to clog the head.
[0046] The pigmented ink composition of the present invention can
be used in any type of printing systems such as ink-jet printing,
offset printing, gravure printing and thermal transfer printing
systems and the like. Among them, the ink composition of the
present invention is preferably used for ink-jet printing. That is,
when the ink composition of the present invention is used with an
ink-jet printer, the above effects of the present invention can be
well attained.
EXAMPLES
[0047] Hereinafter, the present invention will be illustrated by
the following examples, in which "parts" means "parts by weight"
unless otherwise indicated.
Example 1
[0048] In a 100 cc plastic bottle, 4 parts of a copper
phthalocyanine blue pigment ("FASTOGEN BLUE GNPS" available from
Dainippon Ink and Chemicals Incorporated), 4 parts of Dispersant A
[copolymer of styrene/methacrylic acid/butyl acrylate/butyl
methacrylate/polyether macromonomer ("PME 400" available from NOF
Corporation) (weight ratio of 20/10/30/30/10), acid value: 65
mg-KOH/g, weight average molecular weight: 6.0.times.10.sup.4,
molecular weight dispersion: 3.2], 12 parts of diethylene glycol
monobutyl ether monomethyl ester (boiling point: 247.degree. C.) as
an organic solvent and 100 parts of zirconia beads having a
diameter of 3 mm were weighed and charged, and the mixture was
dispersed for 2 hours with a paint shaker (available from TOYO
SEIKI KOGYO CO., LTD.).
[0049] After dispersing, the mixture was diluted with diethylene
glycol monobutyl ether monomethyl ester to obtain Pigmented Ink
Composition A containing 5% by weight of the pigment and 5% by
weight of Dispersant A.
Example 2
[0050] Pigmented Ink Composition B of this Example was prepared in
the same manner as in Example 1 except that Dispersant A was
changed to 4 parts of Dispersant B [styrene/acrylic acid/butyl
acrylate/butyl methacrylate/PME 400 copolymer (weight ratio of
20/10/30/30/10) acid value: 77 mg-KOH/g, weight average molecular
weight: 5.4.times.10.sup.4, molecular weight dispersion: 3.0]. Ink
Composition B contained 5% by weight of the pigment and 5% by
weight of Dispersant B.
Example 3
[0051] Pigmented Ink Composition C of this Example was prepared in
the same manner as in Example 1 except that Dispersant A was
changed to 4 parts of Dispersant C
[styrene/2-acryloyloxyethylsuccinic acid/butyl acrylate/butyl
methacrylate/PME 400 copolymer (weight ratio of 20/10/30/30/10),
acid value: 24 mg-KOH/g, weight average molecular weight;
6.5.times.10.sup.4, molecular weight dispersion; 3.3]. Ink
Composition C contained 5% by weight of the pigment and 5% by
weight of Dispersant C.
Example 4
[0052] Pigmented Ink Composition D of this Example was prepared in
the same manner as in Example 1 except that Dispersant A was
changed to 4 parts of Dispersant D [lauryl methacrylate/methacrylic
acid/butyl acrylate/butyl methacrylate/PME 400 copolymer (weight
ratio of 20/10/30/30/10), acid value: 65 mg-KOH/g, weight average
molecular weight: 6.7.times.10.sup.4, molecular weight dispersion:
3.5]. Ink Composition D contained 5% by weight of the pigment and
5% by weight of Dispersant D.
Example 5
[0053] Pigmented Ink Composition E of this Example was prepared in
the same manner as in Example 1 except that triethylene glycol
dimethyl ester (boiling point: 270.degree. C.) was used in place of
diethylene glycol monobutyl ether monomethyl ester. Ink Composition
E contained 5% by weight of the pigment and 5% by weight of
Dispersant A.
Comparative Example 1
[0054] Pigmented Ink composition F of this Comparative Example was
prepared in the same manner as in Example 1 except that Dispersant
A was changed to 4 parts of Dispersant E [SOLSPER 13940 available
from Avecia, polyester resin, acid value: 8 mg-KOH/g, weight
average molecular weight: 7.3.times.10.sup.3, molecular weight
dispersion: 1.2], and diethylene glycol monobutyl ether monomethyl
ester was changed to liquid paraffin (MOLESCO WHITE P-70 available
from MATSUMOTO SEKIYU KENKYUSHO). Ink Composition F contained 5% by
weight of the pigment and 5% by weight of Dispersant E.
Comparative Example 2
[0055] Pigmented Ink Composition G of this Comparative Example was
prepared in the same manner as in Example 1 except that Dispersant
A was changed to 4 parts of Dispersant F [styrene/butyl
acrylate/butyl methacrylate/PME 400 copolymer (weight ratio of
20/40/30/10), acid value, 0 mg-KOH/g, weight average molecular
weight: 6.3.times.10.sup.4, molecular weight dispersion: 3.2]. Ink
Composition G contained 5% by weight of the pigment and 5% by
weight of Dispersant F.
[0056] Reference Example 1
[0057] Pigmented Ink Composition H of this Reference Example was
prepared in the same manner as in Example 1 except that Dispersant
A was changed to 4 parts of Dispersant G [styrene/methacrylic
acid/butyl acrylate/butyl methacrylate/PME 400 copolymer (weight
ratio of 20/10/30/30/10), acid value: 65 mg-KOH/g, weight average
molecular weight: 4.0.times.10.sup.3, molecular weight dispersion:
1.4]. Ink Composition H contained 5% by weight of the pigment and
5% by weight of Dispersant G.
Reference Example 2
[0058] Pigmented Ink Composition I of this Reference Example was
prepared in the same manner as in Example 1 except that the amount
of Dispersant A was changed from 4 parts to 0.32 part. Ink
Composition I contained 5% by weight of the pigment and 0.4% by
weight of Dispersant G.
[0059] With Ink Compositions A to E of Examples 1-5, Ink
Compositions F and G of Comparative Examples 1 and 2, and Ink
Compositions H and I of Reference Examples 1 and 2, a dispersion
average particle size of the pigment, water resistance and cockling
were measured or evaluated by the following methods:
[0060] Dispersion Average Particle Size:
[0061] A dispersion average particle size of pigment particles in
the pigmented ink composition was measured using a laser Doppler
particle size analyzer (N4-PLUS available from Coulter).
[0062] Printed Layer-Sliding Test:
[0063] A pigmented ink composition was coated on a gloss paper
sheet (SUPER PHOTO GLOSS PAPER available from Hitachi Maxell) with
a #4 bar coater (available from TOYO SEIKI KOGYO CO., LTD.) and
dried for 10 minutes in an atmosphere kept at a temperature of 20
to 25.degree. C. and a humidity of 40 to 60%, and then the printed
layer of the ink composition was slid ten times with a cloth
(BEMCOTTON available from ASONE), on which a weight of 50 g (a
contact area of 3.1 cm.sup.2) was placed at an interval of 3
seconds. Then, the grazing of the printed layer is visually
evaluated. When no grazing of the printed layer was caused, the ink
composition was ranked "A", while grazing was caused, the ink
composition was ranked "B".
[0064] Water Resistance:
[0065] A pigmented ink composition was coated on a plain paper
sheet (available from XEROX) using #4 wire bar (available from TOYO
SEIKI KOGYO CO., LTD.) and then dipped in ion-exchanged water for 1
(one) hour. When no blur occurred, the ink composition was ranked
"A", while when blur occurred, the ink composition was ranked
"B".
[0066] Cockling:
[0067] A pigmented ink composition was coated on a plain paper
sheet (available from XEROX) using #4 wire bar (available from TOYO
SEIKI KOGYO CO., LTD.) and then dried. When the paper sheet was no
cockled, the ink composition was ranked "A", while when the paper
sheet was cockled, the ink composition was ranked "B".
[0068] Anti-Grazing:
[0069] Using an ink-jet printer (MJ-510C available from EPSON), a
gradation test pattern (100, 80, 60, 40 and 20) was continuously
printed on five sheets of gloss paper (SUPER PHOTO GLOSS PAPER
available from Hitachi Maxell) with a pigmented ink composition at
a temperature of 20 to 25.degree. C. and a humidity of 40 to
60%.
[0070] When no grazing of the printed pattern was caused by
discharging or piling, the ink composition was ranked "A", while
grazing was caused, the ink composition was ranked "B". The
presence of grazing was visually evaluated
TABLE-US-00001 TABLE 1 Pigmented Dispersion ink average Water
composi- particle resist- Cock- Anti- Sliding tion size (nm) ance
ling grazing test Ex. 1 A 103 A A A A Ex. 2 B 105 A A A A Ex. 3 C
108 A A A A Ex. 4 D 102 A A A A Ex. 5 E 106 A A A A C. Ex. 1 F 150
A A B B C. Ex. 2 G 220 A A B B Ref. Ex. 1 H 190 A A B B Ref. Ex. 2
I 200 A A B B
[0071] As can be seen from the results in Table 1, in Pigmented Ink
Compositions A to E of Examples 1 to 5 according to the present
invention, the dispersion average particle size of the pigment was
small, no grazing occurred in the printed layer-sliding test, and
the printed layer was not peeled from the printing medium.
Furthermore, they had good water resistance, caused no cockling
when they were printed on the plain paper sheet, and had good
anti-grazing properties when they were printed on the gloss paper
sheet. That is, they satisfied all the properties.
[0072] In contrast, in Pigmented Ink Composition F of Comparative
Example 1 using the conventional dispersant and organic solvent,
the dispersion average particle size of the pigment was rather
large, grazing occurred in the printed layer-sliding test, and the
printed layer was peeled from the printing medium. Furthermore,
they had low anti-grazing properties when they were printed on the
gloss paper sheet. The results were substantially the same when
Pigmented Ink Composition G of Comparative Example 2 comprising the
resin having no acidic group as a dispersant was used.
[0073] Although the resins having the acidic group were used, in
Pigment Ink Composition H of Reference Example 1 in which the
molecular weight of the resin was too small or Pigment Ink
Composition I of Reference Example 2 in which the amount of the
resin was too small, the dispersion average particle size of the
pigment was large, the anti-grazing properties were low when the
ink compositions were printed on the gloss paper sheet.
EFFECTS OF THE INVENTION
[0074] As described above, when the present invention is applied,
it is possible to provide a pigmented ink composition having good
anti-grazing properties, in particular, a pigmented ink composition
for ink-jet printers, which contains a pigment with a small
dispersion particle size and has good water resistance, can be
printed on a plain paper sheet without cockling, and suffers from
no grazing of printed records when the ink composition is printed
on a cationically treated paper sheet.
* * * * *