Title: Ink-jet recording process, ink-jet recorded image and method of alleviating difference in gloss in the ink-jet recorded image
Abstract: The invention relates to a process for producing a high-quality ink-jet recorded image. The process comprises the steps of (i) applying a first ink containing at least one colorant to an opaque printing medium by an ink-jet method to form a visible image; and (ii) applying a second ink, which does not change or substantially not change the hue of the printing medium, to a portion of the printing medium that is complementary to the visible image, thereby alleviating a difference in gloss between the visible image and the portion complementary to the visible image.
Patent Number: 6,863,392 Issued on 03/08/2005 to Shimomura, et al.
| Inventors:
|
Shimomura; Masako (Kanagawa, JP);
Noguchi; Hiromichi (Tokyo, JP);
Kimura; Isao (Kanagawa, JP)
|
| Assignee:
|
Canon Kabushiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
268961 |
| Filed:
|
October 11, 2002 |
Foreign Application Priority Data
| Oct 15, 2001[JP] | 2001/317000 |
| Current U.S. Class: |
347/100; 347/101 |
| Intern'l Class: |
G01D 011//00; B41J 002//01 |
| Field of Search: |
347/95,98,100,101,105
|
References Cited [Referenced By]
U.S. Patent Documents
| 5087601 | Feb., 1992 | Hotta et al. | 503/200.
|
| 5314861 | May., 1994 | Morohoshi et al. | 503/227.
|
| 5686382 | Nov., 1997 | Suzuki et al. | 503/201.
|
| 5837045 | Nov., 1998 | Johnson et al. | 106/31.
|
| 5933164 | Aug., 1999 | Sato et al. | 347/43.
|
| 5952401 | Sep., 1999 | Kimura et al. | 523/161.
|
| 6123411 | Sep., 2000 | Inui et al. | 347/43.
|
| 6193361 | Feb., 2001 | Wen | 347/84.
|
| 6322208 | Nov., 2001 | Bugner et al. | 347/104.
|
| 6428143 | Aug., 2002 | Irihara et al. | 347/43.
|
| 6428862 | Aug., 2002 | Noguchi | 427/511.
|
| 6503307 | Jan., 2003 | Noguchi | 106/31.
|
| 2002/0064603 | May., 2002 | Noguchi | 427/466.
|
| Foreign Patent Documents |
| 1 022 151 | Jul., 2000 | EP.
| |
| 1 057 646 | Dec., 2000 | EP.
| |
| 200-186243 | Jul., 2000 | JP.
| |
| 2000-186242 | Jul., 2000 | JP.
| |
| 2001-277488 | Oct., 2001 | JP.
| |
| 2002-144551 | May., 2002 | JP.
| |
Primary Examiner: Figgins; Ke
Assistant Examiner: Do; An H.
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper & Scinto
Claims
What is claimed is:
1. An ink-jet recording process, comprising the steps of (i) applying a
first ink comprising at least one colorant to an opaque printing medium by
an ink-jet method to form a visible image; and (ii) applying a second ink,
which does not change or substantially not change the hue of the printing
medium, to a portion of the printing medium that is complementary to the
visible image, thereby alleviating a difference in gloss between the
visible image and the portion complementary to the visible image.
2. The ink-jet recording process according to claim 1, wherein a
combination of the printing medium and the first ink provides the visible
image whose surface shows higher gloss than that of the printing medium,
and the second ink increases the surface gloss of the printing medium.
3. The ink-jet recording process according to claim 2, wherein the first
ink further comprises a photo-curing oligomer and a photopolymerization
initiator, and the second ink comprises a photo-curing oligomer and the
photopolymerization initiator.
4. The ink-jet recording process according to claim 1, wherein a
combination of the printing medium and the first ink provides the visible
image whose surface shows lower gloss than that of the printing medium,
and the second ink decreases the surface gloss of the printing medium.
5. The ink-jet recording process according to claim 1, wherein the first
ink is a water-based ink containing a water-insoluble coloring material in
a dispersed state as the colorant, and the second ink comprises a pigment
in a dispersed state.
6. The ink-jet recording process according to claim 5, wherein the pigment
in the second ink is a transparent or achromatic pigment.
7. The ink-jet recording process according to claim 6, wherein the
transparent or achromatic pigment is at least one selected from the group
consisting of silica having an average particle diameter of at most 200
nm, alumina having an average particle diameter of at most 200 nm and
titanium oxide having an average particle diameter of at most 200 nm.
8. A method of alleviating a difference in gloss between a visible image
formed with at least one ink to an opaque printing medium by an ink-jet
method and a portion complementary to the visible image, comprising the
step of applying a second ink, which does not color or substantially not
color the printing medium, to the portion, thereby alleviating a
difference in gloss in the ink-jet recorded image.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink-jet recording process in which
energy is applied to an ink to eject the ink from fine orifices, thereby
conducting recording, and an ink-jet recorded image. The present invention
is suitable for use in the field of commercial printings such as posters
and pamphlets.
2. Related Background Art
The advancement of ink-jet recording techniques in recent years has
permitted achieving high-definition images like a silver salt photograph
by an ink-jet recording method. Both improvement of inks and improvement
of printing media contribute to the achievement of such an image. By the
way, printing media having an ink-receiving layer on a base material to
enhance ink absorbency are often used as printing media used in the
formation of such a high-definition image. However, surfaces of such
printing media include both surfaces having high gloss and comparatively
matt finished surfaces having poor gloss. On the other hand, the gloss of
an image formed on a printing medium varies according to the kind of an
ink used. For example, an image formed with an ink containing a
water-soluble coloring material, specifically, a dye or the like takes
over the gloss of the printing medium as it is. On the other hand, an
image formed with an ink containing a water-insoluble coloring material,
for example, a pigment tends to become an image little in gloss because
the pigment is easy to remain on the surface of the printing medium.
Further, an ink containing a photo-curing resin forms an image having an
extremely smooth surface because a resin film is formed by irradiation of
light after recording. The image often shows high gloss. Therefore, a
great difference in visual gloss arises between an image-formed portion
and an exposed portion of a printing medium existing complementarily to
the image-formed portion according to a combination of the printing medium
and the ink. This difference is considered to be a cause that a person
feels a sense of incompatibility to a high-definition image formed by
ink-jet.
In order to solve such a problem, Japanese Patent Application Laid-Open No.
2002-144551 describes an ink-jet recording process comprising ejecting a
plurality of pigment inks of different colors to a printing medium having
an ink-receiving layer on a base material to record characters and/or
images, wherein an overcoating liquid having a film forming ability is
ejected in a proportion of from 30 to 100% by weight based on a shot-in
ink quantity per unit area to a recorded portion where a shot-in ink
quantity per unit area is at least 50% by weight based on the shot-in ink
quantity per unit area when a shot-in ink quantity per unit area of each
of the plural pigment inks becomes maximum. In other words, the
overcoating liquid is applied to the recorded portion by the pigment inks
hard to achieve high surface gloss to form a film, whereby the gloss of
the recorded portion is improved.
However, this process has failed to sufficiently cope with various
combinations of printing media and inks. In addition, since the film is
additionally formed on the ink-applied portion, the visible image portion
seems to project from the surface of the printing medium. This fact may
give a sense of incompatibility to a person who looks at the image in some
cases.
Japanese Patent Application Laid-Open No. 2001-277488 discloses an ink-jet
recording process comprising using an ink-jet printer having a plurality
of heads for respectively ejecting at least two black inks different in
density and an ink containing no colorant used only at a blank portion of
a printing medium and ejecting the inks to the printing medium from the
plural heads to form an image, wherein the black inks and the ink
containing no colorant contain fine polymer particles having an average
particle diameter of from 10 to 1,000 nm. The Japanese Patent Application
Laid-Open No. 2001-277488 describes at [0021] that the fine polymer
particles preferably form a film during or after drying. However, this
prior art document does not describe anything about an object of the
present invention that a difference in gloss between a black image portion
and a blank portion is alleviated. The investigation by the present
inventors has revealed that the gloss of an image portion formed by the
pigment inks is relatively low, while the gloss of a blank portion formed
by the ink containing no colorant and containing the fine polymer
particles having a film forming ability is high, and so a difference in
gloss between the image portion and the blank portion is not alleviated at
all even by this technique.
SUMMARY OF THE INVENTION
The present inventors have carried out various investigations. As a result,
a technique capable of making uniform the gloss of an ink-jet recorded
image according to various combinations of printing media and inks has
been found, thus leading to completion of the present invention.
It is therefore an object of the present invention to provide an ink-jet
recorded image having no difference in gloss between a visible image
portion and a portion complementary to the visible image portion or little
difference and a production process thereof.
The above object can be achieved by the present invention described below.
According to an embodiment of the present invention, there is provided an
ink-jet recording process, comprising the steps of (i) applying a first
ink comprising at least one colorant to an opaque printing medium by an
ink-jet method to form a visible image; and (ii) applying a second ink,
which does not change or substantially not change the hue of the printing
medium, to a portion of the printing medium that is complementary to the
visible image, thereby alleviating a difference in gloss between the
visible image and the portion complementary to the visible image.
According to another embodiment of the present invention, there is provided
an ink-jet recorded image having a visible image formed on an opaque
printing medium with a first ink by an ink-jet method, wherein a
complementary portion to the visible image on the printing medium has
surface gloss that is equal or substantially equal to the surface gloss of
the visible image, and the surface gloss of the portion is equalized by
applying a second ink to the portion, the second ink does not color or
substantially not color the portion.
According to a further embodiment of the present invention, there is
provided a method of alleviating a difference in gloss between a visible
image formed with at least one ink to an opaque printing medium by an
ink-jet method and a portion complementary to the visible image,
comprising the step of applying a second ink, which does not color or
substantially not color the printing medium, to the portion, thereby
alleviating a difference in gloss in the ink-jet recorded image.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 schematically illustrates an ink-jet recording apparatus according
to an embodiment of the present invention.
FIG. 2 schematically illustrates an ink-jet recording apparatus according
to another embodiment of the present invention.
FIG. 3 is a typical perspective view schematically illustrating the
construction of an ink-jet printer according to an embodiment.
FIG. 4 schematically illustrates an ink-jet printer equipped with an
ultraviolet lamp according to an embodiment.
FIG. 5A is a typical cross-sectional view of a printing medium to which a
first and second inks have been applied, and FIG. 5B illustrates a way of
applying the first and second inks.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will hereinafter be described in more detail with
reference to the preferred embodiments of the invention.
An ink-jet recording apparatus used in an ink-jet recording process
according to the present invention is equipped with a head for ejecting a
second ink applied to a portion, which exists complementarily to a visible
image on a printing medium and will become a background of a visible
image, in addition to heads for ejecting first inks used in the formation
of the visible image. More specifically, for example, a recording
apparatus, in which five recording heads composed of four heads for
ejecting four first inks of yellow (Y), magenta (M), cyan (C) and black
(Bk) for formation of the visible image, respectively, and a head for
ejecting the second ink are arranged on a carriage, is used. An example
thereof is illustrated in FIG. 1. Reference numerals 81, 82, 83 and 84
indicate recording heads for ejecting recording inks of Y, M, C and Bk
colors, respectively. Reference numeral 85 designates a head for ejecting
the second ink applied to the background portion. The heads are arranged
in the above-described recording apparatus and serve to eject the
respective recording inks of Y, M, C and Bk colors according to recording
signals (see 507 in FIG. 5B) and to send a recording signal indicating
that the background portion is colored with a transparent color (see 509
in FIG. 5B) to eject the second ink, thereby completely covering a
printable region of the printing medium with the inks. FIG. 5A is a
schematic cross-sectional view of an ink-jet recorded image obtained by
the above-described process. In FIG. 5A, reference numeral 501 indicates a
printing medium, 503 a visible image portion (colored portion) formed by
applying the first inks, 505 a region (non-colored portion) that forms a
background of the visible image and is applied by the second ink. The
second ink is adjusted in such a manner that the surface gloss of a
portion of the printing medium applied to the second ink is equal or
substantially equal to the surface gloss of the visible image portion. In
the ink-jet recorded image shown in FIG. 5A, there is thus no great
difference in surface gloss between the visible image portion and the
background portion, and the ink-jet recorded image is provided as an image
that a person who looks at the recorded image does not feel a sense of
incompatibility.
Incidentally, it is preferred that printing be carried out so as not to
expose the surface of the printing medium between the visible image
portion 503 and the background portion 505 in FIG. 5A as much as possible.
However, according to how that the inks on the printing medium bleed, the
ink of the non-colored portion may bleed into the colored portion, or the
printing medium may be exposed at a boundary surface if the bleeding is
little. When the degree of exposure of the printing medium is caused by
insufficient bleeding, such exposure does not interfere with the evenness
of glossiness and smoothness.
Non-printed portions (edges) for feeding and discharging the printing
medium in the printer, which are located at the periphery of the printing
medium, are also regarded as non-colored portions and become regions
intended to be printed with the clear ink. In other words, it is also an
embodiment in the scope of the present invention to cover the whole
printed surface of the printing medium with the color inks and non-color
ink. In this case, it can be expected that the durability of the ink-jet
recorded image, such as light fastness and ozone fastness is improved
because the exposed surface of the printing medium is eliminated.
FIG. 1 shows the case where the five recording heads have been used.
However, the present invention is not limited thereto. As shown in FIG. 2,
preference is given even to the case where flow paths of yellow 801Y,
magenta 801M, cyan 801C and black 80Bk inks and a colorless liquid
composition 801S are separately provided in one recording head. It goes
without saying that the construction of the head may be changed so as to
reverse the recording order of the liquid composition and the inks as
described above.
FIG. 3 is a typical perspective view illustrating the schematic
construction of an ink-jet printer according to an embodiment. In FIG. 3,
reference numeral 1504 indicates a scanning rail extending in a main
scanning direction of a carriage 1503 and slidably supporting the
carriage, and 1505 a driving belt for transmitting driving power for
reciprocating the carriage 1503. Reference numerals 1506, 1507 and 1508,
1509 designate pairs of conveying rollers which are arranged in front and
in rear of a printing position by the printing heads and hold and convey a
printing medium 1510. The printing medium 1510 such as paper is guided and
supported on a platen (not illustrated) for regulating a printing surface
flat at the printing position in contact under pressure. At this time,
ejection-orifice-forming faces of the respective head cartridges (heads)
1501, 1502 mounted on the carriage 1503 are located between the printing
medium conveying rollers 1507, 1509 projecting downward from the carriage
1503 so as to oppose in parallel with the printing medium 1510 in contact
under pressure with a guide surface of the platen (not illustrated).
In FIG. 3, on the carriage 1503, six head cartridges in total are
positioned and mounted, and in this embodiment, are arranged in order of a
printing head 1501Y for a yellow ink, a printing head 1501M for a magenta
ink, a printing head 1501C for a cyan ink, a printing head 1501B for a
black ink, a liquid-composition-ejecting head 1502 and a printing head
1501BB for a second black ink from the left side to the right side in FIG.
3. The liquid-composition-ejecting head 1502 serves to eject a liquid
composition reactive to coloring materials in the inks to the printing
medium 1510. The printing head 1501BB for the second black ink arranged at
the right end is a printing head used for a black ink employed, for
example, upon secondary scanning printing in reciprocating printing. More
specifically, the apparatus is so constructed that the
liquid-composition-ejecting head 1502 is arranged next to (on the right
side of) the printing head 1501B for the black ink in the above-described
respective embodiments, and the printing head 1501BB for the second black
ink is further arranged next (at the right end).
In FIG. 3, a recovery unit 1511 is arranged on the left side of the
printing region. In the recovery unit 1511, caps 1512 for capping the
printing heads 1501Y, 1501M, 1501C and 1501B are successively arranged
from the left to the right corresponding to the arrangement of the head
cartridges 1501, 1502, a cap 1513 for capping the
liquid-composition-ejecting head 1502 is arranged next (on the right
side), and a cap 1512 for capping the printing head 1501BB for the second
black ink is further arranged on the right side (at the right end). The
respective caps are provided vertically movably. When the carriage 1503 is
located at the home position, the corresponding caps 1512, 1513 are
brought into contact with the ejection-orifice-forming faces of the
respective heads 1501 and 1502, whereby the ejection orifices of the heads
1501 and 1502 are closely sealed (capped). By this capping, the thickening
or crusting of the inks due to evaporation of solvents in the inks is
prevented, and so occurrence of ejection failure is prevented.
The recovery unit 1511 is also equipped with a suction pump 1514
communicating with the caps 1512 and a suction pump 1515 communicating
with the cap 1513. These pumps 1514 and 1515 are used in capping the
respective ejection-orifice-forming faces with the caps 1512 and 1513 to
practice a suction recovery treatment when the printing heads 1501 and/or
the liquid-composition-ejecting head 1502 cause ejection failure. A blade
1517 for the liquid-composition-ejecting head 1502 is further arranged
between the fifth cap 1513 for the liquid composition from the left end
and the sixth cap 1512 for the black ink (located at the right end), and a
blade 1516 for the respective printing heads 1501 is arranged on the right
side (printing region side) of the cap 1512 located at the right end. The
blade 1517 is held by a blade holder 1519, and the blade 1516 is held by a
blade holder 1518. In this embodiment, these blade holders 1518 and 1519
are lifted and lowered by a blade elevating mechanism (not illustrated)
driven by utilizing the movement of the carriage 1503, whereby the blades
1516 and 1517 are lifted and lowered between a projected position (wiping
position) to wipe the inks and foreign matter attached to the
ejection-orifice-forming faces of the heads 1501 and 1502 and a receded
position (stand-by position) coming into no contact with the
ejection-orifice-forming faces. In this case, the blade 1516 for wiping
the printing heads 1501 and the blade 1517 for wiping the
liquid-composition-ejecting head 1502 are constructed in such a manner
that they can be caused to separately go up and down independently of each
other.
Any inks may be used as inks suitable for use in the present invention so
far as they can be used in printing by an ink-jet printer.
In the present invention, which ink should be used as the second ink is
determined according to a combination of the printing medium and the first
inks. More specifically, when an ultraviolet-curing inks are used as the
first inks as described above, a transparent film of an ultraviolet-curing
oligomer is formed at a colored portion irrespective of the kind of a
coloring material such as a dye or pigment, and so the smoothness is
enhanced, and the glossiness becomes higher than the printing medium. In a
portion high in image density, the glossiness becomes higher than its
surrounding portion of the printing medium, while in a portion low in
image density, irregularities are caused between a film-formed portion and
a non-colored portion of the printing medium, and the glossiness of the
printed portion is felt uneven. When the first inks are pigment inks, a
pigment is fixed to the surface of the printing medium unlike dye inks
coloring the surface of the printing medium. Glossiness differs between
the printing medium and the printed portion according to image density and
the kind of paper used. Since smoothness of the printed surface is almost
equal to that of the printing medium such as paper having low surface
smoothness, semiglossy paper, plain paper or matted paper (high-quality
exclusive paper; trade name: HR101, product of Canon Inc., or the like),
the glossiness of the resulting print is uniform irrespective of image
density. In paper very high in smoothness or a film (trade name:
Professional Photo-paper PR101; or trade name: Glossy Film HG201, product
of Canon Inc.) by which an image quality like a silver salt photograph is
achieved, however, irregularities of pigment particles fixed to the
printing medium are greater than irregularities of the printing medium
itself, and so the glossiness is worsened. In paper classified between
matted paper and very high glossy paper, i.e., the so-called ordinary
paper for photograph (photo-glossy paper; trade name: GP301, product of
Canon Inc.), irregularities of the printing medium itself are greater than
irregularities of pigment particles fixed to the printing medium, and so
the glossiness becomes high at a portion high in image density. It is
important to suitably prepare the second ink according to the combination
of the printing medium and the first inks.
The constitution of the present invention will hereinafter be described in
more detail by two embodiments.
(First Embodiment)
First inks containing a pigment as a coloring material:
When the first inks contain a pigment as a coloring material, and the
printing medium is paper very high in surface smoothness or a film, most
of the pigment is located at the surface of the printing medium or at the
surface and in the vicinity of the surface. Therefore, the glossiness of
the surface of a visible image portion becomes lower than the surface
gloss of the printing medium. Accordingly, the second ink is preferably
formulated so as to lower the surface gloss of the printing medium. As
such a second ink, is preferred an ink containing inorganic fine particles
having an average particle diameter of at most 200 .mu.m, such as alumina
sol, silica sol or titanium oxide finely divided, or transparent or
achromatic fine particles of a resin dispersed in water, such as a latex
or dendrimer, or the like for the purpose of adjusting the smoothness.
When the average particle diameter is greater than 200 .mu.m, a nozzle is
clogged, and the shelf stability of the resulting ink is deteriorated due
to precipitation or the like. It is hence not preferable to use any fine
particles having an average particle diameter greater than 200 .mu.m. The
fine particles are produced by crushing, grinding, solution polymerization
or the like, and classification treatment is conducted if necessary. A
surface treatment may also be conducted as necessary for the end
application intended, such as improvement in dispersibility. Any fine
particles may be used. Plural kinds of fine particles having either a
relatively great particle diameter or a relatively small particle diameter
may also be used for the purpose of adjusting the glossiness. In order to
adjust the glossiness or protect the printing medium from light, gases,
water and stain, such a polymer component that forms a transparent film
after evaporation of water may preferably be contained. As the polymer
component, is preferred a pigment dispersant such as an acrylic resin,
styrene-acrylic acid resin or benzyl acrylate, or a substance used in a
coating layer of printing media, such as polyvinyl alcohol, cellulose,
water-soluble chitosan, starch or polyethylene oxide having a molecular
weight of at least 1,000, or an analogue thereof. The fine particles and
film-forming polymer may be suitably selected according to the kinds of
the inks used in the colored portion and the printing medium used.
In both first and second inks, the following compounds are preferably
formulated into inks taking into consideration the fact that they are
applied to a printing medium by an ink-jet method. In order to enhance
reliability of heads, such as anti-clogging of nozzles, an organic solvent
having a high boiling point may preferably be added. Examples of
preferable organic solvents include glycol ethers, glycols, aprotic polar
solvents, glycerol, urea, urea derivatives such as ethyleneurea and
dihydroxyethylurea, and lower alkyldiols having at most six carbon atoms.
However, the aprotic polar solvents and glycol ethers are excellent as
those having an effect without increasing the viscosity of the resulting
ink. In order to enhance the persistency of printing and penetrability
into printing media, a small amount of a surfactant or a lower alcohol
having at most three carbon atoms may also be added. Examples of
preferable surfactants include surfactants such as polyoxyalkyl ethers,
polyoxyalkyl esters, Pluronics obtained by block-polymerizing ethylene
oxide and propylene oxide, acetylene glycol-ethylene oxide adducts, and
dimethylsiloxane-ethylene oxide-propylene oxide adducts. Besides,
additives such as mildewproofing agents, pH adjusters, such as inorganic
alkalis such as sodium hydroxide, potassium hydroxide and lithium
hydroxide, alkanolamines such as triethanolamine, dibasic acids such as
oxalic acid, succinic acid, malonic acid, gluconic acid and adipic acid,
and organic acids such as formic acid, acetic acid and propionic acid,
ultraviolet absorbents, water-proofing agents, inorganic salts such as
ammonium sulfate, organic salts, and chelating agents for scavenging
impurity metals may be added if necessary. In order to prevent bleeding at
boundaries between color inks and a black ink, a polyvalent metal salt may
be added to non-black inks for colored portion. Polyvalent metals include
Zn.sup.2+, Mg.sup.2+, Ca.sup.2+, Cu.sup.2+, Co.sup.2+, Ni.sup.2+,
Fe.sup.2+, La.sup.3+, Nd.sup.3+, Y.sup.3+ and Al.sup.3+. However, the
present invention is not limited thereto. Preferable anions bonded to
these ions include No.sub.3.sup.-, F.sup.-, Cl.sup.-, Br.sup.-, I.sup.-,
CH.sub.3 COO.sup.- and SO.sub.4.sup.2-.
In an ink-jet printer, an ink set composed of five color inks of yellow,
magenta, cyan, black and clear inks or an ink set composed of seven color
inks in total with a pale cyan ink and a pale magenta ink added thereto
when a high-definition image like a photograph is provided is used.
Besides, inks of special colors such as green, orange, dark yellow and
gray may be used without any problems.
The construction of printing heads is preferably such that printing heads
for the respective colors are transversely arranged in a row or vertically
arranged in plural rows.
As a system of ejecting ink droplets, may be used either a system in which
recording signals are applied to an ink within a printing head to eject
ink droplets by thermal energy generated, or a system in which ink
droplets are ejected by vibration of a piezoelectric oscillator using a
piezoelectric element.
(Second Embodiment)
Use of a coloring material, a photo-curing oligomer and a
photopolymerization initiator in first inks:
A feature of a photo-curing ink resides in that the glossiness and
smoothness of a printed portion become high irrespective of the kind of
the printing medium because the ink is excellent in film-forming ability.
Accordingly, it is also necessary to formulate an ink, by which both
glossiness and smoothness will become high, as a second ink applied to a
background portion. In general, an ink obtained by removing a coloring
material from the first ink used in the formation of a visible image is
preferred. In both first inks and second ink, materials used in the
preparation of the inks, such as an ultraviolet-curing oligomer and a
photopolymerization initiator are preferably high in solubility in water
taking into consideration the ejection stability, long-term shelf
stability, transparency and the like of the resulting inks.
As the ultraviolet-curing oligomer is preferred an oligomer having an
acryloyl group, methacryloyl group or vinyl group in its molecule and at
least two polymerizable functional groups in its molecule. Those disclosed
in Japanese Patent Application Laid-Open Nos. 2000-186242 and 2000-186243,
such as those obtained by polyfunctionalizing a polymerizable functional
group such as an epoxyacrylate, urethaneacrylate or acrylate using
polyethylene glycol, glycerol, trimethylolpropane, pentaerythritol or the
like and adding a necessary amount of ethylene oxide to obtain necessary
water-solubility, are preferred. However, the present invention is not
limited thereto so far as polymerizable substances are radical-polymerized
by ultraviolet light. All the above-mentioned ultraviolet-curing oligomers
may be used after a necessary amount of a hydroxyl group, sulfonic group,
carboxyl group or ammonium group is added to enhance the water-solubility.
As the photopolymerization initiator, is preferred a photo-cleaving
.alpha.-hydroxyphenyl ketone, Irgacure 2959 (trade name; product of Ciba
Specialty Chemicals) or a derivative thereof, a proton-abstracting
thioxanthone derivative (used in combination with a proton donor typified
by a tertiary alkanolamine, or the like. The photopolymerization initiator
may also be used after a necessary amount of ethylene oxide, or a hydroxyl
group, sulfonic group, carboxyl group or ammonium group is added to
enhance the water-solubility. A reactive diluent may also be used in
combination to facilitate a photopolymerization reaction. As the reactive
diluent, is preferred morpholine acrylate, vinylpyrrolidone or the like.
In order to dissolve the photopolymerization initiator and the
ultraviolet-curing oligomer, a small amount of an organic solvent used for
the inks described in the first embodiment may be added into the ink. It
is also permissible that the above-described surfactants, additives,
alcohols having at most three carbon atoms, pH adjusters, bleed preventing
agents and/or organic acids are used in order to stably conduct printing
or improve the shelf stability of the resulting inks. As the coloring
materials of the first inks, the pigments described in the first
embodiment may be used as they are. However, preferred dyes are azo
metallized dyes which form complexes with an metal ion and are hard to be
faded by irradiation of ultraviolet light. As the ultraviolet-curing
oligomer, photopolymerization initiator, reactive diluent, organic solvent
and additives, may be used the same substances as described above.
In order to cure the transparent ultraviolet-curing ink and the
ultraviolet-curing inks, it is necessary that an ultraviolet lamp be built
in an ink-jet printer to emit ultraviolet light just after the printing or
at the same time as the printing so as to irradiate a printing medium with
the ultraviolet light at the same time as the printing to momentarily fix
the inks to the printing medium. Even when the printer and the ultraviolet
lamp are not integrally formed, the lamp must be arranged about the
printer so as to emit ultraviolet light immediately after the printing.
An example where an ultraviolet lamp is arranged in a printer is
illustrated in FIG. 4. Reference numeral 1 indicates an ink-jet printing
head, 2 an ink-jet printer, 3 a feeding section of a printing medium, 4 a
discharging section of the printing medium, and 5 an ultraviolet lamp
built in a lamp cover.
The ultraviolet lamp is preferably such a low pressure mercury lamp that
the vapor pressure of mercury is 1 to 10 Pa during lighting, a high
pressure mercury lamp, or a mercury lamp coated with a fluorescent
substance. The emission spectra in an ultraviolet range of these mercury
lamps fall within a range of from 184 to 450 nm and are suitable for
causing a polymerizable substance in a black or colored ink to efficiently
react. Since a small-sized power source may be used, such a mercury lamp
is preferred from the viewpoint of mounting the power source in the
printer.
As the ultraviolet lamp, may be basically used a metal halide lamp, high
pressure mercury lamp, ultrahigh pressure mercury lamp, xenon flash lamp,
a lamp using deep UV or microwave to excite a mercury lamp from the
outside without using any electrodes, or UV laser because the above range
is included as an emission wavelength range so far as the size of the
power source, input intensity, lamp form and the like are permissible. A
filter may be provided to cut wavelengths of 254 nm or shorter at which
ozone is generated, or a lens is installed to focus light. A necessary
cumulative dose of ultraviolet light is 500 to 5,000 mJ/cm2. If the
cumulative dose is insufficient, the adherence of the ink crusted to the
printing medium, and glossiness are not sufficiently exhibited. In the
case of a color ink, water fastness may become insufficient in some cases.
EXAMPLES
Ink compositions investigated in the present invention will hereafter be
described. In the ink compositions, all designations of "%" mean % by
weight unless expressly noted. Water means purified water or ion-exchanged
water.
First Ink:
(a) Set of Ultraviolet-Curing Inks:
Inks of the following materials and formulating ratio were used.
Formulation Y ink M ink C ink Bk ink
Pigment IJX273B 24.8
dispersion IJX266D 21.6
(*1) IJX253C 24.7
Cab-O-jet 300 26.2
Ultraviolet-curing oligomer 10 10 10 10
(*2)
Photopolymerization 2 2 2 2
initiator (*3)
Water 63.2 66.4 63.3 61.8
Name of pigment Concentration
dispersion Name of pigment of pigment
IJX273B Pigment Yellow 155 16.1
IJX266D Pigment Red 122 18.9
IJX253C Pigment Blue 15:3 16.2
Cab-O-jet 300 Pigment Black 7 19.1
(*1) As the pigment dispersions, were all used self-dispersing pigment
dispersions prepared according to the technique disclosed in U.S. Pat. No.
5,837,045 (Cabot Corporation), in which a sulfonic group was bonded to the
surface by a chemical reaction.
(*2) As the ultraviolet-curing oligomer, was used a trifunctional oligomer
(trade name: IRR289; product of Daicel UCB Co., Ltd.).
(*3) As the photopolymerization initiator, was used Irgacure 2959 (trade
name; product of Ciba Specialty Chemicals) added with 4 moles of ethylene
oxide.
(b) Set of Pigment Inks:
Formulation Y ink M ink C ink Bk ink
PY155 24.8
PR122 21.6
PB15:3 24.7
PBK7 26.2
1,5-Pentanediol 10 10 10 10
Water 65.2 68.4 65.3 63.8
As the pigment dispersions, were used the following dispersions prepared by
using an acrylic alkali-soluble water-soluble polymer as a dispersant and
conducting pH adjustment with potassium hydroxide.
Average
Pigment Name of Concentration particle
dispersion pigment of pigment pH diameter
Yellow Pigment 16.1 9.0 189
Yellow 155
Magenta Pigment Red 18.9 9.2 164
122
Cyan Pigment 16.2 9.0 106
Blue 15:3
Black Pigment 19.1 9.6 113
Black 7
Second Ink:
(A) Ultraviolet-curing clear ink:
IRR289 (product of Daicel UCB Co., Ltd.) 10%
Ethylene oxide adduct of Irgacure 2959 2%
(product of Ciba Specialty Chemicals)
Water 88%.
(B) Clear ink for pigment ink:
Alumina (120 nm) 3%
Styrene-acrylic acid resin (molecular Weight: 1%
7,000)
2-Pyrrolidone 5%
Triethylene glycol monobutyl ether 5%
Adduct of acetylene glycol with 10 moles of 1%
Ethylene oxide
Water 85%
(C) Ultraviolet-curing clear ink:
IRR289 (product of Daicel UCB Co., Ltd.) 10%
Ethylene oxide adduct of Irgacure 2959 2%
(product of Ciba Specialty Chemicals)
Dispersion of titanium oxide 3%
(particle Diameter: 180 nm; in terms of pigment
solid Concentration)
Water 85%
Printing Media:
Evaluation was conducted with the following printing media:
Glossy film (HG201, product of Canon Inc.);
Glossy paper (PR101, product of Canon Inc.); and
Glossy paper (GP301, product of Canon Inc.).
The first inks, second inks and printing media used in Examples and
Referential Examples are shown in Table 1.
TABLE 1
First ink set Second ink set Printing medium
Example 1 a C Glossy film HG201
Example 2 a A Professional
photo-paper PR101
Example 3 a A Glossy paper GP301
Example 4 b B HG201
Example 5 b B PR101
Example 6 b B GP301
Ref. a Not used HG201
Example 1
Ref. a Not used PR101
Example 2
Ref. a Not used GP301
Example 3
Ref. b Not used HG201
Example 4
Ref. b Not used PR101
Example 5
Ref. b Not used GP301
Example 6
A printer and a printing method are as follows. The second ink was charged
into a container portion for water-proofing and strengthening agents for
plain paper in an ink-jet printer (trade name: BJF8500, manufactured by
Canon Inc.), and the respective inks making up the first ink set were
charged into respective ink container portions of Y, M, C and Bk colors.
The application of the second ink to a non-colored portion was performed
at a necessary portion (non-colored portion of the printing medium) while
a head was reciprocated once on a carriage in the same manner as in the
formation of a visible image by the respective inks of Y, M, C and Bk
colors. In Examples where a photopolymerizable ink was used for a
non-colored printed portion or colored portion, an ultraviolet lamp
(bright line spectrum: 365 nm) of the rare gas type was arranged at a
portion in which the printing medium was discharged to precure a print,
and the print was then completely cured by an ultraviolet irradiation
apparatus (F300D, Lamp Type D, manufactured by Fusion System Japan). The
complete curing was conducted under conditions that the print was passed
through the ultraviolet irradiation apparatus once at a conveyer speed of
3 m/min. As a printing pattern, a gradation pattern having an image
density of 0 to 50% was prepared by using the respective inks of Y, M, C
and Bk colors.
Ink-jet recorded images were formed as references of the respective
Examples in the same manner as in their corresponding Examples except that
no second ink was applied to the non-colored portion, and the references
were regarded as Referential Examples 1 to 6, respectively.
With respect to the ink-jet recorded articles obtained in the Examples and
Referential Examples, each of the images was lifted to the height of the
eyes to visually observe it, thereby conducting evaluation as to the
uniformity of gloss. As a result, the ink-jet recorded articles according
to the Examples had no marked difference in gloss between the visible
image portion and the non-recorded portion making up the background of the
visible image portion, and uniform gloss was observed in the whole image.
On the other hand, in the ink-jet recorded articles according to the
Referential Examples as references, a difference in gloss was observed
between the visible image portion and the non-recorded portion, and gloss
was lost with respect to the whole image. From this fact, it was confirmed
that the ink-jet recorded articles according to the present invention are
extremely effective for provision of still higher-quality images.
The ink-jet recorded articles obtained in Examples 1 to 6 were subjected to
the following gas-proof test. More specifically, the respective recorded
articles were left to stand for 36 hours in a chamber in which a mixed gas
composed of nitrogen dioxide (1250 ppb), sulfur dioxide (300 ppb) and
ozone (1200 ppb), which deeply participate to discoloration of printing
media, had been charged. Incidentally, the gas concentrations described
above correspond to the condition that the recorded articles was left to
stand for 3 months in a room. With respect to the recorded articles before
placed in the chamber and after left to stand in the chamber, LE values of
non-colored portions at four corners of each printing medium were
measured. As a result, the AE values were all smaller than 5, and no
discoloration of the printing media was visually observed. It was found
from this result that good durability can be imparted to the ink-jet
recorded articles according to the present invention because exposed
portions of the printing media are eliminated.
According to the present invention, the glossiness of a print can be made
uniform by suitably adjusting the composition of a clear ink even when
both pigment inks by which the gloss of a printing medium is lost, and
ultraviolet-curing inks which exhibit higher glossiness than the printing
medium are used. In addition, discoloration or fading of non-printed
portions in a print by gases is prevented because the printing medium
itself has no exposed portion, and so the long-term shelf stability of the
print is improved.
*
