U.S. patent application number 09/179577 was filed with the patent office on 2002-03-21 for image forming process.
Invention is credited to EGUCHI, TAKEO, KURABAYASHI, YUTAKA.
Application Number | 20020033869 09/179577 |
Document ID | / |
Family ID | 26562409 |
Filed Date | 2002-03-21 |
United States Patent
Application |
20020033869 |
Kind Code |
A1 |
KURABAYASHI, YUTAKA ; et
al. |
March 21, 2002 |
IMAGE FORMING PROCESS
Abstract
An image forming process capable of forming an image having high
fretting resistance and water resistance by an ink-jet ejecting
method using an ink containing a pigment which can be dispersed
without a dispersant and smoothly transferring into a thermoplastic
resin layer.
Inventors: |
KURABAYASHI, YUTAKA; (TOKYO,
JP) ; EGUCHI, TAKEO; (YOKOHAMA-SHI, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Family ID: |
26562409 |
Appl. No.: |
09/179577 |
Filed: |
October 27, 1998 |
Current U.S.
Class: |
347/100 ;
347/102 |
Current CPC
Class: |
B41J 2/2107 20130101;
C09D 11/30 20130101; B41M 5/0023 20130101; B41M 7/009 20130101;
B41M 5/0064 20130101 |
Class at
Publication: |
347/100 ;
347/102 |
International
Class: |
B41J 002/01; B41J
002/325; G01D 015/16; B41J 031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 1997 |
JP |
09-312869 |
Oct 22, 1998 |
JP |
10-300664 |
Claims
What is claimed is:
1. An image forming process comprising steps of: (i) providing a
recording medium having a substrate and a thermoplastic resin layer
which constitutes an outermost layer of said recording medium; (ii)
ejecting an aqueous ink containing a pigment capable of being
dispersed in water without a dispersing agent toward an outside
surface of the thermoplastic resin layer by employing an ink-jet
ejecting method, thereby attaching the pigment onto the outside
surface of the thermoplastic resin layer; and (iii) transferring
the pigment from the outside surface of the thermoplastic resin
layer into the thermoplastic resin layer.
2. The image forming process according to claim 1, wherein said
step (iii) comprises a step of heating said recording medium of
which the pigment has been attached on the outside surface of said
thermoplastic resin layer.
3. The image forming process according to claim 1, wherein said
thermoplastic resin layer is a porous layer.
4. The image forming process according to claim 3, wherein said
thermoplastic resin layer contains thermoplastic resin
particles.
5. The image forming process according to claim 1, wherein said
pigment capable of being dispersed in water without said dispersing
agent is a carbon black having a modified surface.
6. The image forming process according to claim 5, wherein the
carbon black having a modified surface is a carbon black of which a
hydrophilic group is bound for the surface thereof directly or
through an atomic group.
7. The image forming process according to claim 6, wherein said
hydrophilic group is at least one group selected from a group
consisting of those which are listed below: --COOM, --SO.sub.3M,
--PO.sub.3HM, --PO.sub.3M.sub.2, --SO.sub.2NH.sub.2,
--SO.sub.2NHCOR, --NH.sub.3.sup.+, --NR.sub.3.sup.+, 3wherein M
represents a hydrogen atom, an alkali metal, an ammonium or a
quaternary ammonium, R designates a straight-chain or
branched-chain alkyl group having 1 to 12 carbon atoms, a
substituted or unsubstituted phenyl group or a substituted or
unsubstituted naphthyl group.
8. The image forming process according to claim 6, wherein the
atomic group is an alkylene group having 1 to 12 carbon atoms, a
substituted or unsubstituted phenylene group or a substituted or
unsubstituted naphthylene group.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an image forming process
which is capable of speedily forming images of higher
qualities.
[0003] 2. Related Background Art
[0004] The ink-jet ejecting method which has characteristics of
facilitating to accelerate a recording speed, enhance resolution,
lower noise, diversify image colors and broaden an adaptability to
diversified recording patterns is rapidly prevailing in recent days
for recording letters such as Chinese characters first of all,
obtaining hard copies of various kinds of figure information and
for other purposes of use. Owing to compatibilities with various
kinds of inks and the adaptability to diversified recording
patterns, the ink-jet ejecting method is attracting attention as
means for obtaining color hard copies of computer terminals and so
on. Further, attempts are being made to apply a multi-color ink-jet
ejecting method even to the fields of multi-color printing and
color photograph printing since the multi-color ink-jet ejecting
method is capable of providing images which are not inferior in
qualities to those formed by the ordinary multi-color printing and
allows a small number of copies at a cost lower than that required
for the ordinary plate making method. Though aqueous dyes have
conventionally been used exclusively as color materials of inks for
the ink-jet ejecting method, pigments are now usable as color
materials for inks, thereby making it possible to obtain clear
image having excellent color tones.
[0005] The ink-jet ejecting method is generally classified into: a
pressure oscillation type such as electric charge control method
and electric field control method; a static electricity
acceleration type which electrostatically accelerates an ink with a
voltage applied across electrodes opposed to each other; a pressure
pulse type such as an on-demand type which pushes out an ink with
pressure pulses; and an ink mist type which produces an ink mist
with an ultrasonic oscillation; each of which forms an image by
attaching drops of a liquid ink to a recording medium.
[0006] However, papers of certain high grades, coated papers,
baryta papers and resin-coated papers used as substrates of
photographic printing papers, transparent polymer films used as
light transmissive recording media for overhead projectors, etc.
are inferior in ink absorptivities, whereby unabsorbed inks may
remain for a long time on surfaces of recording media when these
papers are used as recording media for the ink-jet ejecting method.
In such a case, if the unabsorbed inks are brought into contact
with portions of printers, operators touch the unabsorbed inks or
sheets which are discharged successively are overlapped so as to
rub recording surfaces, images may be fouled or the inks may flow
out, thereby making it impossible to obtain clear images.
[0007] In order to record images of high qualities on such
recording media by the ink-jet ejecting method, it is conceivable
to dispose an ink receiving layer which has an ink absorptivity
high enough to speedily absorb an ink attached to a recording
medium, thereby setting it in an apparently dry condition. An ink
receiving layer which has a large number of voids can be mentioned
as an example of an ink receiving layer having an ink absorptivity
high enough to meet the requirement.
[0008] In order to form an ink receiving layer which has a high ink
absorptivity, it is carried out, for example, to use thermoplastic
resin particles as a material of an ink receiving layer which
absorbs and holds an ink into voids formed among the particles.
When the voids formed among the particles have a size smaller than
a color material contained in the ink, however, the color material
may remain on a recording medium, thereby posing a problem in
fretting resistance of a formed image. An image formed with an ink
which uses a dye as a color material poses no serious problem in
the fretting resistance or water resistance. This fact is
considered due to a fact that particles of the dye dissolved in the
ink are sufficiently small and can easily penetrate voids in an ink
receiving layer of a recording medium. In case of an image formed
with an ink which contains a pigment larger than the dye, in
contrast, its fretting resistance and water resistance are
influenced by a size of the pigment and a size of the voids. In
other words, the ink-jet ejecting method which uses an ink
containing a pigment allows a quality of an image to be influenced
by matching between an ink and a recording medium, or is hardly
capable of stably forming images of high qualities.
SUMMARY OF THE INVENTION
[0009] The present invention has been achieved in view of the
aforementioned background and an object of the present invention is
to provide an image forming process which makes it possible to
stably obtain image of higher qualities by utilizing an ink-jet
ejecting method which uses an ink containing a pigment.
[0010] According to one aspect of the present invention, there is
provided an image forming process comprising steps of: (i)
providing a recording medium having a substrate and a thermoplastic
resin layer which constitutes an outermost layer of the recording
medium;
[0011] (ii) ejecting an aqueous ink containing a pigment which can
be dispersed into water without a dispersing agent toward an
outside surface of the thermoplastic resin layer by an ink-jet
ejecting method, thereby attaching the pigment to the outside
surface of the thermoplastic resin layer; and
[0012] (iii) transferring the pigment from the outside surface of
the thermoplastic resin layer into the thermoplastic resin
layer.
[0013] The inventors made various examinations to accomplish the
object described above and found a fact that: a pigment may not
transfer smoothly into a thermoplastic resin layer when a general
pigment ink which contains a pigment and a dispersing agent
therefor is attached to a recording medium having a surface
composed of a thermoplastic resin layer, and then the recording
medium is heated, whereas an image of an extremely high quality can
be formed in the similar procedures when a carbon black as a
pigment which can be dispersed into water without a dispersing
agent (hereinafter referred to in short as a self-dispersion type
carbon black) is selected as a color material and an ink to which
no dispersing agent is added is used. On the basis of this
knowledge, the inventors considered that a dispersing agent
contained in the general pigment ink governs a mutual solubility
between a pigment and a thermoplastic resin and a mobility of a
pigment on a surface of a thermoplastic resin layer into the
thermoplastic resin layer, thereby achieving the present
invention.
[0014] The image forming process according to the embodiment of the
present invention allows a pigment which is attached to a surface
of a thermoplastic resin layer by an ink-jet ejecting method to
transfer into the thermoplastic resin layer so that it is covered
with the thermoplastic resin, thereby being capable of forming an
image of an extremely high quality which is excellent in fretting
resistance, water resistance and durability. Further, the image
forming process according to the present invention achieves a
quality of an image which being not influenced by relationship
between a size of a pigment and a size of pores in a surface of a
recording medium, thereby making it possible to form images of a
uniform quality.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a vertical sectional view of a head section of an
ink-jet recorder;
[0016] FIG. 2 is a cross sectional view of the head section of the
ink-jet recorder;
[0017] FIG. 3 is an external perspective view of the head section
of the ink-jet recorder;
[0018] FIG. 4 is a perspective view exemplifying an ink-jet
recorder;
[0019] FIG. 5 is a longitudinal sectional view of an ink
cartridge;
[0020] FIG. 6 is a perspective view of a recording unit;
[0021] FIG. 7 is a perspective view of a recording section wherein
a recording head which is used in an embodiment of the present
invention is arranged in a plurality;
[0022] FIG. 8 is a perspective view of another recording head to be
used for the image forming process according to the present
invention;
[0023] FIGS. 9A and 9B are schematic sectional views of recording
media to be used in the embodiment of the present invention: FIG.
9A showing a recording medium having a composition wherein a
thermoplastic resin layer is formed on a substrate, and FIG. 9B
showing a recording medium having a composition wherein a
substrate, an ink receiving layer and a thermoplastic resin layer
are laminated;
[0024] FIG. 10 shows a composition wherein a thermoplastic resin
layer is configured as a layer which contains thermoplastic resin
particles; and
[0025] FIGS. 11A and 11B are diagrams descriptive view of the image
forming process according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] Now, the present invention will be described in more detail
with reference to a preferable embodiment of the present
invention.
[0027] With reference to FIGS. 9A and 9B, description will be made
of a recording medium which is usable for the image forming process
according to the present invention and has a thermoplastic resin
layer on a substrate.
[0028] As a substrate 901 for a recording medium to be used for the
image forming process according to the present invention, there can
be mentioned a transparent film which is made of a material such as
polyester, polysulfone, polyvinyl chloride, polycarbonate,
polystyrene, polymethylmethacrylate, cellulose acetate,
polyethylene, polypropylene and the like, a white film which can be
obtained by charging a white pigment or producing fine bubbles in
the material mentioned above or an opaque sheet like material such
as a general paper, coated paper, a baryta, a resin-coated paper, a
metal foil and the like.
[0029] Usable as the white pigment to be charged in a paper or a
film is, for example, a substance such as titanium oxide, calcium
sulfate, calcium carbonate, silica, clay or talc which is
ordinarily used as a charging material, a pigment for paints and
kneading material. Though a thickness of the substrate is not
limitative for the present invention, it is general to use a
substrate of 10 .mu.m to 300 .mu.m thick.
[0030] Usable as the substrate 901 is a substrate 901-1 which has
an ink receiving layer 901-2 for improving ink absorptivity
disposed on a surface thereof as shown in FIG. 9B. Usable as a
material to compose the ink receiving layer 901-2 is, for example,
a water-soluble or hydrophilic polymer which can receive the
so-called aqueous ink and exhibits solubility or affinity to the
aqueous ink. Examples of such a polymer are polyvinyl alcohol,
polyurethane, carboxymethyl cellulose, polyester, polyacrylate
(ester), hydroxyethyl cellulose, melamine resin or synthetic resins
of modifications thereof and natural resins such as albumin,
gelatin, casein, starch, cationized starch, gum arabic, and sodium
alginate. It is allowed to use a plurality of these substances at
the same time.
[0031] In order to form the ink receptor layer 901-2, a coating
liquid is prepared by dissolving or dispersing such a polymer in
water, an alcohol, a polyhydric alcohol or another adequate organic
solvent. The substrate 901 shown in FIG. 9B can be obtained by
coating a surface of the substrate 901-1 with the prepared coating
liquid, for example, by the roll coater method, blade coater
method, air knife coater method, gate roll coater method, bar
coater method, size press method, spray coating method,
photogravure coater method, curtain coater method or the like, and
then drying the coating liquid in a hot-air drying furnace, a
heated drum or the like.
[0032] The ink receiving layer 901-2 may contain filler additives.
Examples of the filler are silica, alumina, aluminium silicate,
magnesium silicate, basic magnesium carbonate, talc, clay,
hydrotalcite, calcium carbonate, titanium oxide, zinc oxide and
plastic pigments such as polyethylene, polystyrene, polyacrylate
and the like. The ink receptor layer may contain one, two or more
fillers selected from among these substances. Further, it is
possible to optionally add other additives, for example,
surface-active agents, dye sealing agents (water resistants),
anti-foaming agents, anti-oxidizing agent, fluorescent brightening
agents, ultraviolet absorbers, dispersants, viscosity modifiers, pH
adjusting agents, mildewproofing agents and plasticizers.
[0033] As examples of substrates or recording media which have such
ink receiving layers, there can be mentioned coated papers
manufactured for the ink-jet ejecting method, transparent films for
OHP and general glossy papers. CA-101, HG-201 and CF-301 (all
manufactured by Canon Inc.) are examples of such recording media
which are commercially available.
[0034] A thermoplastic resin layer 903 is formed on at least one of
surfaces of a substrate described above. In order to improve
adhesion of a thermoplastic resin to the surface of the substrate,
it may be subjected to a corona discharge treatment, sandblasting
treatment, a flame treatment or other general adhesion improving
treatment or an undercoat layer may be disposed on a surface of the
substrate on which the thermoplastic resin layer is to be disposed.
As a material which is selectable to form the undercoat layer,
there can be mentioned, for example, a resin such as gelatin,
nitrocellulose and the like.
[0035] Now, description will be made of the thermoplastic resin
layer. In order to impart sufficiently excellent fretting
resistance and water resistance to informed images, it is
preferable to use a material which allows at least a portion of a
thermoplastic resin layer to be softened or melted within a range
where it does not influence a self-holding property of a recording
medium when the recording medium is heated, whereby a pigment
adhering to an outside surface of the thermoplastic resin layer is
taken into the thermoplastic resin layer. Though different
dependently on heating temperatures to be set, concrete materials
of the thermoplastic resin layers are, for example, aromatic
compounds of polymonovinylidene (for example, polystyrene,
polymethyl sulfone, polymetoxy styrene and polychrolostyrene),
polyolefin, poly-halo-olefin (for example, polyvinyl chloride,
polyvinyl cyclohexane, polyethylene, polypropylene and
polyvinylidene chloride), esters of .alpha., .beta.-ethylenic
unsaturated acid (ester of polymethacrylate, ester of
polychloracrylate, ester of polymethylmethacrylate) and various
kinds of copolymers containing monomers thereof. A thermoplastic
resin layer which contains these materials can be formed, for
example, by dissolving the materials mentioned above in an adequate
solvent and coating a substrate with a solution thus prepared.
[0036] It is preferable to compose the thermoplastic resin layer so
as to contain resin particles made of the materials mentioned above
as shown in FIG. 10. The reason is that the thermoplastic resin
layer has pores on an outside surface thereof to which an ink
supplied by the ink-jet ejecting method adheres easily.
[0037] As the thermoplastic resin which is used in a condition of
fine particles for the image forming process according to the
present invention, it is preferable to select plastic pigment which
is in the so-called slurry condition prepared by suspending and
polymerizing one or more kinds of vinylic monomers. The plastic
pigment is usable in a dried condition, or may be fine powders
obtained by crushing a solid-state plastic made of the materials
mentioned above or powders which are formed as fine particles of
the materials. It is preferable to use fine particles of the
thermoplastic resin which have a mean particle diameter of 0.05 to
20 .mu.m, or more preferable to use fine particles which have a
mean particle diameter of 0.1 to 12 .mu.m.
[0038] As a method to form a thermoplastic resin layer which
contains the fine particles of the thermoplastic resin, there can
be mentioned a method which comprises preparing a coating liquid by
dispersing particles of the thermoplastic resin in an adhesive
agent and coating a substrate with the liquid. To prepare the
coating liquid, it is possible to use as the adhesive agent, for
example, starches such as an oxidized starch, an etherified starch
and an esterified starch and dextrin, cellulose derivatives such as
carboxymethyl cellulose and hydroxyethyl cellulose, casein,
gelatin, soybean protein, polyvinyl alcohol and derivatives
thereof, maleic acid anhydride resin, general styrene-butadiene
copolymer, conjugate diene polymer latices such as methyl
methacrylate-butadiene copolymer, acrylic polymer latices such as
polymers and copolymers of ester acrylate and ester methacrylate,
vinylic polymer latices such as a copolymer of ethylene acetate,
polymer latices of these kinds of polymers which have functional
groups modified by monomers containing functional groups such as
carboxyl group and thermoset resins such as melamine resin and urea
resin. Further, it is possible to additionally use starches and
polyvinyl alcohol which are cationically denaturated as well as
cationic resins which contain nitrogen.
[0039] If necessary, the coating liquid may preliminarily be
blended, for example, with adequate amounts of a pigment
dispersant, a viscosity builder, a fluidity modifier, an anti-foam
agent, a foam inhibitor, a mold-releasing agent, a coloring agent
and the like. However, it is preferable to use materials which do
not influence a mobility of the pigment into the thermoplastic
resin layer in amounts within ranges free from influences on the
precipitation of the pigment.
[0040] To form the thermoplastic resin layer by applying the
coating liquid which has the composition described above to the
substrate, it is possible to use any of coaters, for example, a
blade coater, an air knife coater, a roll coater, a brush coater, a
curtain coater, a champlex coater, a bar coater and a photogravure
coater which is generally used for manufacturing papers coated with
pigments (coated papers).
[0041] At a step to form the thermoplastic resin layer, the coating
liquid may be applied to the substrate in a required amount at a
time or repeatedly two or more times so as to obtain a desired
thickness. Taking into consideration a mobility of a pigment and
image qualities (fretting resistance, etc.) to be finally obtained,
it is preferable that the thermoplastic resin layer has a thickness
of 1 to 200 .mu.m or 3 to 50 .mu.m in particular.
[0042] After the coating liquid is applied to the substrate as
described above, the thermoplastic resin layer may be formed by
drying. For drying the coating liquid applied to the substrate, it
is possible to use a general heating method which uses, for
example, a gas heater, an electric heater, a steam-heated oven or a
hot-air heater. During heating by the method described above, it is
preferable to limit a temperature of a top surface below a melting
point of the thermoplastic resin or the fine particles of the
thermoplastic resin used as a material of the thermoplastic resin
layer. Such limitation of the drying temperature for the
thermoplastic resin layer at the drying step makes it possible to
prevent an ink absorptivity from being lowered due to filming of
the thermoplastic resin layer or densification of the film.
[0043] After allowing an ink to adhere to an outside surface of the
thermoplastic resin layer of a recording medium by the ink-jet
ejecting method, the thermoplastic resin layer is heated so as to
be softened or partially melted, thereby allowing the ink to settle
into the thermoplastic resin layer, thereby allowing an ink to
precipitate into the thermoplastic resin layer. As a heating
method, there can be mentioned a method to heat a surface of the
thermoplastic resin layer by bringing it into pressure contact with
a heated metal plate or a metal roll, irradiating it with heat
radiation from an electric heater or an infrared lamp, or exposing
it to a hot blast. It is effective for obtaining a smooth surface
to bring a transparent and smooth plastic film into contact with
the outside surface of the thermoplastic resin layer and bond it by
heating at the stage to heat the thermoplastic resin layer with a
hot blast or heat radiation. Further, it is allowed to interpose a
thermally fusible plastic powder or plastic film between the
thermoplastic resin layer and the film to be placed on the surface
of the thermoplastic resin layer before melting the thermoplastic
resin layer. By configuring the surface which is to be heated and
brought into pressure contact with the outside surface of the
thermoplastic resin layer as a mirror surface, coarse surface or a
surface having special patterns curved thereon, it is possible to
obtain desired lustre or form desired irregularities on the outside
surface after the heating and melting.
[0044] For preventing degradation of the thermoplastic resin layer
and enhancing weather resistance of color materials composing
images formed by the ink-jet ejecting method, it is desirable to
prepare the thermoplastic resin layer in a condition where it
contains, for example, an ultraviolet-absorbing agent, an
anti-oxidizing agent, a mold-releasing agent and/or a stabilizer
which are ordinarily used for thermoplastic resins.
[0045] As an aqueous ink for the image forming method according to
the present invention, it is preferable to use an ink containing a
pigment as a coloring material which can be dispersed in water
without a dispersant. An aqueous medium in which a pigment is
dispersed without using a dispersant such as an aqueous polymer is
usable as an ink for ink-jet ejecting method. By applying such an
ink to the outside surface of the thermoplastic resin layer of the
recording medium described above by the ink-jet ejecting method and
then heating the recording medium, almost all of the pigment on the
recording medium which serves for forming an image is allowed to
transfer into the thermoplastic resin layer. In other words, almost
all of the pigment can be covered with a film of the thermoplastic
resin. This merit is considered due to a fact that the transfer of
the pigment adhering to the outside surface of the thermoplastic
resin layer into the thermoplastic resin layer is not hindered by a
dispersant (for example, aqueous polymer). Further, an image formed
in this way is clearer and has a more excellent color tone as
characteristics of an image formed with the pigment.
[0046] As a pigment which can be dispersed in water without a
dispersant, it is preferable to select a pigment which contains, as
a color material, a self-dispersion type carbon black whose surface
is combined with at least one hydrophilic group by way of another
atomic group. Unlike the conventional pigment inks, an ink which
uses such a carbon black as a color material makes it unnecessary
to add a dispersant for dispersing a carbon black. When a
dispersibility in an ink is taken into consideration, it is
preferable to select as the self-dispersion type carbon black one
which is anionically or cationinally charged.
[0047] As carbon blacks which are anionically charged, there can be
mentioned those which have surfaces combined, by way of other
atomic groups, with hydrophilic groups, for example, --COOM,
--SO.sub.3M, --PO.sub.3HM, --PO.sub.3M.sub.2, --SO.sub.2NH.sub.2,
and --SO.sub.2NHCOR (wherein M is a hydrogen atom, an alkali metal,
an ammonium or an organic ammonium and R is an alkyl group having 1
to 12 carbon atoms, a substituted or unsubstituted phenyl group, or
a substituted or unsubstituted naphthyl group). Out of these carbon
blacks, self-dispersion type carbon blacks which have surfaces
combined with at least either of --COOM and --SO.sub.3M by way of
another atomic group and are anionically charged exhibit favorable
dispersibility in inks and are used preferably in particular.
Lithium, sodium or potassium can be mentioned as the alkali metal
in the hydrophilic group which is represented by the chemical
symbol M, and mono-, di- and trimethyl ammonium, mono-, di-, and
triethyl ammonium and mono-, di- and trimethanol ammonium can be
mentioned as the organic ammonium in the hydrophilic group which is
represented by the chemical symbol M.
[0048] As a method for forming a self-dispersion type carbon black
which is anionically charged, there can be mentioned, for example,
a method which combines --Ar--COONa group (wherein Ar represents an
allyl group) with a surface of a carbon black by bringing nitrous
acid into reaction with an NH.sub.2--Ar--COONa group so as to
produce diazonium salt.
[0049] As a method for forming a self-dispersion type carbon black
which has a surface combined with --COOM, there can be mentioned,
for example, a method which enhances a degree of an oxidation of
commercially available acidic carbon black.
[0050] An acidic carbon black can be obtained by adequately
oxidizing a coloring carbon black such as furnace black or channel
black by an oxidation method which uses an ordinary oxidizing
agents (for example, nitric acid, ozone, hydrogen peroxide,
nitrogen oxide) or a surface improving method such as plasma
treatment. Such acidic carbon blacks are placed on the market under
trade names of "MA100", "2400B" and "MA8" by Mitsubishi Chemical
Industries Ltd. and a trade name of "Color Black FW200" by Degusa
Co.
[0051] When such an acidic carbon black is to be used for the image
forming process according to the present invention, it is further
oxidized to obtain an acidic carbon black which is oxidized to a
higher degree than the ordinary carbon black, and its surface
quality is improved, for example, with a hypohalite. Though sodium
hypochlorite and potassium hypochlorite can be mentioned as
hypohalites which are usable for this oxidation or improvement of
surface quality, it is preferable to use sodium hypochlorite from a
viewpoint of a reactivity.
[0052] A method to oxidize an acidic carbon black will be described
below. To oxidize an acidic carbon black, it is general to put the
acidic carbon black and a hypohalite (for example, sodium
hypochlorite) at an effective halogen concentration of 10 to 30% by
weight of a carbon black are put into an adequate amount of water,
and agitate the water for at least 5 hours, preferably
approximately 10 to 15 hours at 50.degree. C. or higher, preferably
95 to 105.degree. C. A carbon black thus obtained contains surface
active hydrogen, for example, at 1.5 mmol/g or higher.
[0053] Then, a product is filtered and washed with ion-exchanged
water to remove by-product salts. Further, the product is purified
and concentrated using a separating membrane such as a reverse
osmosis membrane or an ultrafilter membrane which has a pore
diameter of 0.01 .mu.m or smaller. The concentration is generally
carried out so as to obtain a thick pigment dispersion liquid which
has a carbon black content on the order of 10 to 30% by weight of
water. A pigment dispersion liquid thus obtained contains no
dispersant and is usable with no additional treatment as an aqueous
pigment ink for the ink-jet ejecting method.
[0054] Alternately, the concentrated pigment dispersion liquid may
be further dried to prepare a powdery pigment or further
concentrated to prepare a pigment paste which contains the pigment
on the order of 50% by weight. By dispersing the powdery pigment or
the pigment paste in an aqueous solvent subsequently and adjusting
them at a desired concentration, it is possible to obtain an
aqueous pigment ink which is usable for the ink-jet ejecting
method.
[0055] (Cationic Hydrophilic Group)
[0056] As a cationically charged carbon black, there can be
mentioned a carbon black which has a surface combined, for example,
with at least one of quaternary ammonium groups listed below:
[0057] --NH.sub.3.sup.+, --NR.sub.3.sup.+, 1
[0058] As a method for forming a self-dispersion type carbon black
which is combined with a hydrophilic group described above and
cationically charged, there can be mentioned a method which treats
a carbon black with 3-amino-N-ethyl pyridium bromide to combine an
N-ethyl pyridyl group having, for example, a composition shown
below: 2
[0059] A carbon black which is anionically or cationically charged
by introducing a hydrophilic group into a surface of the carbon
black as described above has an excellent water dispersibility
owing to repulsion of ions, thereby maintaining a stable dispersed
condition even when it is contained in an aqueous ink without
adding a dispersant or the like.
[0060] Each of the hydrophilic groups mentioned above may be
combined directly with a surface of a carbon black. Alternately,
another atomic groups may be interposed between the surface of the
carbon black and the hydrophilic group so that the hydrophilic
group is combined indirectly with the surface of the carbon black.
As the other atomic group, there can be mentioned, for example, a
straight-chain or branched-chain alkylene group having 1 to 12
carbon atoms, a substituted or unsubstituted phenylene group or a
substituted or unsubstituted naphthylene group. As a substituted
phenylene group and a substituted naphthylene group, there can be
mentioned, for example, a straight-chain or branched-chain alkylene
group having 1 to 6 carbon atoms. Further, concrete examples of a
combination the other atomic group and the hydrophilic group are
--C.sub.2H.sub.4--COOM, --Ph--SO.sub.3M, --Ph--COOM and so on
(wherein the chemical symbol Ph represents a phenyl group).
[0061] It is possible to adequately use two or more kinds selected
from among the self-dispersion type carbon blacks as color
materials for an ink. It is preferable to add the self-dispersion
type carbon blacks at a ratio by weight of 0.1 to 15% of a total
weight of an ink or within a range from 1 to 10% by weight in
particular of a total weight of an ink. When the self-dispersion
type carbon blacks are added at a ratio within this range, the
carbon blacks are capable of maintaining a sufficiently dispersed
conditions in an ink. It is possible to add a dye as a color
material for adjusting a color tone of an ink according to the
present invention.
[0062] When the oxidized carbon black described above is oxidized
for use as a pigment which can be dispersed in water without a
dispersant, it is preferable to use, for example, a dye which has
an anionic group as a solubilization group.
[0063] Water-soluble acidic dyes, direct dyes and reactive dyes
which are listed in the Color Index can be used with no special
limitation as water-soluble dyes having anionic groups. Further, it
is possible to use dyes which are not listed in the Color Index so
far as they have anionic groups, for example, a sulfone group, a
carboxyl group or the like. Needless to say, the water-soluble dyes
include those which have solubilities varying dependently on pH
levels. These dyes are used in inks at 1 to 10% by weight,
preferably within a range from 1 to 5% by weight.
[0064] In case of an aqueous pigment ink which uses no dispersant
as described above, it is preferable to adjust the ink as a whole
in a neutral or alkaline condition. Such an adjustment is
preferable to prepare an aqueous ink which is more excellent in
long-term shelf stability. When durabilities of various members
used in an ink-jet recorder are taken into consideration, it is
desirable to adjust the aqueous ink within range from pH 7 to
10.
[0065] As pH adjusting agents to be used for this purpose, there
can be mentioned, for example, organic amines such as
diethanolamine, triethanolamine and the like, inorganic alkaline
agents such as hydroxides of alkali metals such as sodium
hydroxide, lithium hydroxide, potassium hydroxide and the like,
organic acids and mineral acids.
[0066] An aqueous medium to be used in an ink is water or a mixture
solvent consisting of water and a water-soluble organic solvent. It
is preferable to use not general water which contains various kinds
of ions but ion-exchanged water (deionized water).
[0067] As a water-soluble organic solvent which is to be used in
the condition mixed with water, there can be mentioned, for
example, an alkyl alcohol having 1 to 4 carbon atoms such as methyl
alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol,
n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol and the
like; an amide such as dimethylformamide, dimethylacetamide and the
like; a ketone or a keto alcohols such as acetone, diacetone
alcohol and the like; an ether such as tetrahydrofuran, dioxane and
the like; a polyalkylene glycol such as polyethylene glycol,
polypropylene glycol and the like; an alkylene glycol which has an
alkylene group containing 2 to 6 carbon atoms such as ethylene
glycol, propylene glycol, butylene glycol, triethylene glycol,
1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol
and the like; glycerine; a lower alkyl ether of a polyhydric
alcohol such as ethylene glycol monomethyl (or ethyl) ether,
diethylene glycol methyl (or ethyl) ether, triethylene glycol
monomethyl (or ethyl) ether; N-methyl-2-pyrrolidone, 2-pyrrolidone,
1,3-dimethyl-2-imidazolidinon. Out of these large number of
water-soluble organic solvents, polyhydric alcohols such as
diethylene glycol and lower alkyl ethers of polhydric alcohols such
as triethylene glycol monomethyl (or ethyl) ether are
preferable.
[0068] A content of the water-soluble organic solvent mentioned
above is generally within a range from 3 to 50% of a total weight
of an ink, preferably within a range from 3 to 40% by weight.
Further, water is to be used at a ratio of 10 to 90% of a total
weight of an ink, preferably within a range from 30 to 80% by
weight.
[0069] In order to obtain an aqueous ink which has desired physical
properties, an ink which is to be used for the image forming
process according to the present invention can contain optionally
adequate amounts of a viscosity modifier, a surface-active agent,
an anti-foaming agent, an antiseptic, an antioxidant and so on in
addition to the components described above. Further, the ink may
contain optionally the water-soluble dyes described above as color
materials in addition to the pigments mentioned above.
[0070] To manufacture an ink to be used for the image forming
process according to the present invention which has the
composition described above, a pigment is first added to an aqueous
medium which contains at least water, agitated and then dispersed
by dispersing means described later and subjected optionally to
centrifugal separation, thereby preparing a desired fluid
dispersion. Then, a sizing and additive components which are
adequately selected as described above are added to the fluid
dispersion, and agitated to prepare an ink to be used for image
forming process according to the present invention.
[0071] Any one of general dispersing apparatuses, for example, a
ball mill, a roll mill and sand mill can be used to disperse the
pigment mentioned above in an aqueous medium. Out of these
dispersing apparatuses, it is preferable to use a high-speed type
sand mill, for example, Super Mill, Sand Grinder, Bead Mill,
Agitator Mill, Grain Mill, Dynou Mill, Pearl Mill or Cobol Mill (by
trade names).
[0072] When an ink such as that described above is to be used for
the ink-jet ejecting method, a pigment which has an optimum
particle size distribution is adopted from a viewpoint of
requirements for resistance to clogging and so on. A pigment which
has a desired particle size distribution can be obtained by
reducing a size of grinding medium of a dispersing apparatus,
enhancing a charging ratio of the grinding medium, prolonging a
treatment time, slowing down an ejecting speed, classifying
particles with a filter or a centrifuge after grinding or a
combination of these techniques.
[0073] Further, an anionic surface-active agent or anionic
macromolecular substance is usable as an anionic compound to be
contained in an aqueous ink. The anionic compound is to be added at
0.05 to 10% by weight, preferably at 0.2 to 5% by weight.
[0074] Furthermore, it is preferable that the ink contains an
amphoteric surface-active agent which has been adjusted to a pH
level not exceeding an isoelectric point thereof. A preferable
example of the anionic surface-active agent is any one of
carboxylate type, esther sulfate type, sulfonate type and esther
phosphate type surface-active agents which are generally used.
Further, an example of the anionic polymer is an alkali-soluble
resin, concretely sodium polyacrylate or a polymer partially
copolymerized with acrylic acid, which is not limitative needless
to say.
[0075] The image forming method according to the present invention
forms an image by applying the aqueous ink described above to a
recording medium by the ink-jet ejecting method such as that shown
in FIGS. 11A and 11B, and heating it so as to transfer the pigment
into the thermoplastic resin layer (1101 in FIG. 11A, and 1103 in
FIG. 11B). As a result, a transparent and lustrous image which is
excellent in water resistance, fretting resistance and weather
resistance is formed on the recording medium while making use of
the merit of the pigment to provide excellent sharpness, color
reproducibility and color density for images.
[0076] When a transparent polymer film is used as a substrate of a
recording medium for the image forming process according to the
present invention, an image is formed on a film which is completely
transparent, whereby the image has excellent sharpness, color
reproducibility, color density, water resistance, fretting
resistance and weather resistance. The film is usable as an
excellent original sheet for overhead projectors.
[0077] When a high grade printing paper such as a paper coated with
a white pigment, a baryta paper, a resin-coated paper and the like
or a photographic substrate is used as a substrate of the recording
medium, an image which is formed by the ink-jet ejecting method is
obtained as a lustrous film on an opaque substrate. As a result,
the image forming process according to the present invention is
capable of providing highly lustrous images which are excellent in
color reproducibility, color density and resolution.
[0078] When a substrate having a silk-finish surface, a fine
particle surface or the like which is known in the photographic
field is used, obtained images have surfaces corresponding to that
of the substrate. By pressing a surface of the top layer to an
embossing surface after the top surface is softened or melted and
before it is filmed by heating, it is possible to obtain an image
which has an embossing surface corresponding to the embossing
surface by the ink-jet ejecting method.
[0079] Now, description will be made of a recorder which employed
in the ink-jet ejecting method according to the present invention
described above. It is preferable to configure the recorder as a
type which imparts recording signals to an ink reserved in a
recording head and ejects liquid drops with a heat energy produced
by the recording signals. A configuration of a recording head which
is a main member of the recorder is illustrated in FIGS. 1, 2 and
3.
[0080] A head 13 is composed by cementing a glass, ceramic or
plastic member which has a groove 14 for passing an ink to a heat
generating head 15 which has an exothermic resistor used for
thermographic recording (a thin-film head shown in the drawings is
not limitative). The heat generating head 15 consists of a
protective film 16 made of silicon oxide or the like, aluminium
electrodes 17-1 and 17-2, an exthothermic resistor layer 18 made of
nichrome or the like, a heat accumulating layer 19 and a substrate
20 which is made of a material such as alumina having high heat
radiating property.
[0081] A recording ink 21 has attained to a ejecting orifice 22 and
forms a meniscus 23 under a pressure P.
[0082] When an electric signal is applied to the aluminium
electrodes 17-1 and 17-2, a region n of the heat generating head 15
which abruptly generates heat, air bubbles are produced in the ink
21 which is in contact with the region n and the meniscus 23
protrudes under a pressure of the air bubbles, whereby the ink 21
discharges while forming small drops 24 and jumps from the orifice
22 toward a recording medium 25.
[0083] FIG. 3 shows a schematic diagram of a recording head in
which a nozzle shown in FIG. 1 is arranged in a large number. To
make the recording head, the glass plate 27 having a large number
of flow paths is adhered to the heat generating head 28 similar to
that described in FIG. 1.
[0084] In connection with the above, FIG. 1 is a sectional view of
the head 13 disposed along the ink flow path and FIG. 2 is a
sectional view taken along an 2-2 line in FIG. 1.
[0085] FIG. 4 exemplifies an ink-jet recorder in which the
recording head is assembled.
[0086] In FIG. 4, a reference numeral 61 represents a blade used as
a wiping member, whose one end is fixed or held by a blade holding
member so as to form a cantilever. The blade 61 is disposed at a
location adjacent to a recording region for a recording head 65 and
held in a protruding condition in a moving path of the recording
head 65 in this embodiment.
[0087] A reference numeral 62 designates a cap for an ink ejecting
port surface of the recording head 65 which is disposed at a home
position adjacent to the blade 61 and configured to move in a
direction perpendicular to a moving direction of the recording head
65 until it comes into contact with the ink ejecting port surface
and functions as a cap. A reference numeral 63 denotes an ink
absorber which is disposed at a position adjacent to the blade 61
and held, like the blade 61, in a protruding condition in the
moving path of the recording head 65. The blade 61, the cap 62 and
the ink absorber 63 compose a ejection recovery section 64, and the
blade 61 and the ink absorber 63 remove water, dust, etc. from the
surface of the ejecting port.
[0088] A reference numeral 65 represents a recording head which has
ejection energy generating means and performs recording by ejecting
an ink to a recording medium opposed to a ejecting port surface in
which ejecting ports are arranged, a reference numeral 66
designates a carriage for moving the recording head 65 which is
mounted thereon. The carriage 66 is slidably engaged with a guide
shaft 67 and partially connected (not shown) to a belt 69 which is
driven by a motor 68. Accordingly, the carriage 66 can move along
the guide shaft 67 so as to move the recording head 65 within the
recording region and adjacent regions.
[0089] A reference numeral 51 represents a paper feeder into which
a recording medium is to be inserted and a reference numeral 52
designates a paper feeding roller which is driven by the motor 68.
This configuration allows the recording medium to be fed to a
location opposite to the ink ejecting port surface of the recording
head 65 and discharged into a discharged paper section in which a
paper discharge roller 53 is arranged as the recording
progresses.
[0090] While the recording head 65 returns to its home position in
the configuration described above upon termination of recording or
a similar stage, the cap 62 of the ejection recovery section 64
retreats from the moving path of the recording head 65, but the
blade 61 protrudes into the moving path. As a result, the blade 61
wipes the ejecting port surface of the recording head 65. When the
cap 62 is contacted with the ejecting port surface of the recording
head 65 for capping, the cap 62 is moved so as to protrude into the
moving path of the recording head 65.
[0091] When the recording head 65 is to move from the home position
to a recording start position, the cap 62 and the blade 61 are
located at the positions which are the same as those at the wiping
time. As a result, the ejecting port surface of the recording head
65 is wiped also during the movement of the recording head 65.
[0092] The recording head 65 moves to the home position not only
upon termination of recording and a ejection recovery time but it
moves to the home position adjacent to the recording region at
predetermined intervals also while it is moving within the
recording region for recording, whereby the recording head 65 is
also wiped along with the movements.
[0093] FIG. 5 is a diagram exemplifying an ink cartridge 45 which
accommodates an ink supplied to the head by way of an ink supply
member, for example, a tube. A reference numeral 40 represents an
ink reservoir, for example, an ink bag, which accommodates the
supplied ink and has a rubber stopper 42 at its tip. When a needle
(not shown) is inserted into the stopper 42, the ink can be
supplied from the ink bag 40 to the head. A reference numeral 44
designates an ink absorber which receives waste ink.
[0094] It is preferable to use an ink reservoir having a liquid
contact surface to be brought into contact with the ink which is
made of polyolefine, in particular, polyethylene.
[0095] Not only the ink-jet recorder consisting of the head and the
ink cartridge which are configured separately as described above
but also a recorder consisting of a head and an ink cartridge which
are integrated with each other is preferably usable to carry out
the image forming process according to the present invention as
shown in FIG. 6.
[0096] In FIG. 6, a reference numeral 70 represents a recording
unit which accommodates an ink reservoir, for example an ink
absorber, which reserves an ink and is configured so as to allow
the ink reserved in the ink absorber to be ejected as ink drops
from a head 71 having a plurality of orifices. Polyurethane, for
example, can be used as a material of the ink absorber. A reference
numeral 72 designates an atmosphere communication port for
communicating an interior of the recording unit with atmosphere.
The recording unit 70 which is used in place of the recording head
shown in FIG. 4 is freely attachable to and detachable from the
carriage 66. Though the ink-jet recorder which is configured to
eject the ink drops by exerting the heat energy to the ink as been
described above as a recorder to carry out the image forming
process according to the present invention, it is also possible to
utilize a piezoelectric type ink-jet recorder which uses a
piezoelectric element.
[0097] A recorder in which four recording heads shown in FIG. 3 are
arranged on a carriage, for example, is used to carry out the image
forming method according to the present invention. FIG. 7 shows an
example of such a recorder. Reference numerals 81, 82, 83 and 84
represent recording heads which eject yellow, magenta, cyanic and
black recording inks respectively. These heads are arranged in the
recorder described above and eject the recording inks of different
colors in accordance with recording signals. Though the four heads
are arranged in the example shown in FIG. 7, this configuration is
not limitative, and it is preferable to form separate liquid flow
paths for yellow, magenta, cyanic and black inks in a single
recording head as shown in FIG. 8.
[0098] The present invention will be described more concretely with
reference to preferred embodiments of the present invention,
wherein "part" and "%" are to be taken as weight standards unless
otherwise specified.
EXAMPLES 1 to 3
[0099] Images were formed and evaluated through steps a to c which
are described below:
[0100] (a. Manufacturing of Recording Medium)
[0101] A coating liquid was prepared by adding 45 parts of water to
5 parts of polyvinyl alcohol adopted as an adhesive agent and
further adding 50 parts of latex containing the thermoplastic resin
particles listed in Table 1. This coating liquid was applied to
Transparency Film CF-301 prepared by Canon Inc. so as to obtain 5
g/m.sup.2 of solid matter. Recording medium having thermoplastic
resin particle layers 5 .mu.m thick which were formed as top layer
on ink receiving layers were manufactured by heating substrates at
70.degree. C.
1TABLE 1 Thermoplastic Resin Particles Used in Examples Mean
Thermoplastic resin particle particle Name Manufacturer diameter
Example 1 Styrene-butadiene type latex Nippon Zeon 0.16 .mu.m
(Trade name: Nipol LX303; Tg = 100.degree. C.) Example 2 (Trade
name: Chemi-Pearl Mitsui 0.5 .mu.m S-300; Tg = 94.degree. C.)
Petrochemical Industries, Ltd. Example 3 (Trade name: Chemi-Pearl
Mitsui 3 .mu.m W-100; Tg = 115.degree. C.) Petrochemical
Industries, Ltd.
[0102] (b. Preparation of Inks)
[0103] CAB-O-JET 200 and CAB-O-JET 300 (trade names; prepared by
Cabot Co., Ltd.) were prepared as pigment dispersing materials
containing pigments which can be dispersed in water without a
dispersing agent. CAB-O-JET 200 is a pigment dispersing material at
pH 7.8 containing a self-dispersion type carbon black (mean
particle diameter 130 nm) which has a sulfone group on a surface
thereof and is dispersed at a ratio of 20% by weight.
[0104] Further, CAB-O-JET 300 is a pigment dispersing material at
pH 7.8 containing a self-dispersion type carbon black (mean
particle diameter 150 nm) which has a carboxyl group on a surface
thereof and is dispersed at a ratio of 15% by weight. Using these
pigment dispersing materials, inks having compositions shown in
Table 2 below were prepared. Each of the inks was manufactured by
mixing components and agitating them for 12 hours with a
stirrer.
2TABLE 2 Compositions of Inks Used in Examples 1 to 3 Composition
of ink Example 1 Example 2 Example 3 Cabojet 200 20 wt % 15 wt % --
Cabojet 300 -- -- 3 wt % C. I. Food Black 2 -- 1 wt % 1.2 wt %
Diethylene glycol 9 wt % -- 7 wt % Ethylene glycol -- 12 wt % --
Glycerine 8 wt % 10 wt % 9 wt % Ethanol 4 wt % 6 wt % -- Isopropyl
alcohol -- -- 5 wt % Water Rest wt % Rest wt % Rest wt %
[0105] (c. Image Formation and Evaluation)
[0106] Using the recording medium obtained at the step a) and
aqueous inks prepared at the step b), images were formed with
Printer BJC-400J manufactured by Canon Inc. 30 minutes after
forming the images, top layers of the recording medium were heated
to temperatures specified in Table 3 and maintained at these
temperatures for 20 minutes to form the images.
[0107] Then, fretting resistance and water resistance of the images
thus obtained were evaluated by the procedures and according to
evaluation standards which are described below. The results are
shown in Table 3.
[0108] Evaluation Standards
[0109] (1) Fretting Resistance
[0110] Images, monochromatic images and alphanumerics were rubbed
with dry tissue papers. No adhesion of color materials contained in
inks to the tissue papers was evaluated as o, whereas adhesion of
the color materials to the tissue papers was evaluated as x.
[0111] (2) Water Resistance
[0112] Images, monochromatic images and alphanumerics which were
formed on the recording medium through the steps described above
were left standing for one hour in atmosphere at room temperature
and then submerged for 10 seconds in city water at 20.degree. C.
The images were taken out of the water, air-dried and visually
checked for water resistance. Evaluation standards were:
[0113] .circleincircle.: Pigment or dye did not flow into blanks
and base surfaces of recording medium were scarcely fouled. The
alphanumerics are scarcely blurred.
[0114] o: Pigment or dye scarcely flowed into blanks and base
surfaces of recording medium were scarcely fouled. The
alphanumerics were slightly blurred but the blurring is not
problematic for practical use.
[0115] x: Pigment or dye scarcely flowed into blanks and base
surfaces of the recording medium were scarcely fouled. The
alphanumerics were rather blurred and problematic for practical
use.
3TABLE 3 Medium Heating Temperatures and Image Evaluation Results
Medium heating Fretting Water temperature resistance resistance
Example 1 110.degree. C. .smallcircle. .circleincircle. Example 2
140.degree. C. .smallcircle. .circleincircle. Example 3 135.degree.
C. .smallcircle. .circleincircle.
COMPARATIVE EXAMPLE 1
[0116]
4 [Preparation of black ink] Macromolecular dispersing agent* 40
parts Carbon black 24 parts (Trade name: MA100: prepared by
Mitsubishi Chemical Industries, Ltd.) Ethylene glycol 20 parts
Water 16 parts *Macromolecular dispersing agent: Aqueous solution
of anionic polymer (an aqueous solution of styrene-methacrylic
acid-ethyl acrylate: acid value 400, weight-average molecular
weight 6000, solid matter 20% by weight, neutralizing agent:
monoethanolamine)
[0117] The materials mentioned above were put together with glass
beads having a diameter of 1 mm into a vertical type batch sand
mill (manufactured by Imex Co.) and treated for three hours while
cooling with water. After dispersion, the liquid had a viscosity of
9 cps and a pH value of 10. This liquid was centrifugalized with a
centrifugal separator to remove coarse particles, thereby obtaining
a black ink containing a dispersing agent which had a mean particle
diameter of 135 m.mu. and a solid matter of 13%.
[0118] Images were formed in the same procedures as those for
Example 1 (medium heating temperature: 110.degree. C.), except for
use of the ink which is manufactured as described above.
Observation of the recorded images indicated that a pigment
adhering to a surface of a recording medium did not transfer
sufficiently into a thermoplastic resin layer. Further, the images
did not exhibit sufficiently high fretting resistance.
[0119] As understood from the foregoing description, the present
invention provides an image forming process by a convenient ink-jet
recording method which is capable of forming sharp images having
high fretting resistance and water resistance even on substrates
which have low ink absorptivities.
* * * * *