FIELD OF THE INVENTION AND RELATED ART
[0001] The present invention relates to a printing process.
[0002] Hitherto, planographic offset printing, letterpress printing, etc., have been used
as printing processes. In these conventional printing processes, there have been used
liquid high-viscosity printing inks comprising vehicles therefor which comprise drying
oils, semidrying oils, high-boiling point solvents, resins, etc. Accordingly, in the
conventional printing processes, it is very inconvenient to handle the printing ink
when it is supplied to a printing press or machine, or the printing ink tends to stain
clothes or hands very often.
[0003] Further, in the conventional printing process, when the printing machine supplied
with the printing ink is as such left standing for a long time, the printing ink is
dried whereby it is impossible to resume the printing. As a result, in the conventional
printing process, the maintenance of the printing machine is very troublesome.
SUMMARY OF THE INVENTION
[0004] An object of the present invention is to provide a printing process wherein the printing
ink to be used is easy to handle, and the resumption thereof is easy even after the
printing machine supplied with the printing ink is as such left standing for a long
time.
[0005] According to the present invention, there is provided a printing process comprising:
liquefying an ink which is solid at room temperature; applying the liquefied ink onto
a plate having a pattern; and transferring the ink from the plate to a transfer-receiving
medium thereby to form thereon an ink pattern corresponding to the pattern of the
plate.
[0006] These and other objects, features and advantages of the present invention will become
more apparent upon a consideration of the following description of the preferred embodiments
of the present invention taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007]
Figure 1 is a schematic side sectional view showing an embodiment of the apparatus
for practicing the printing process according to the present invention; and
Figure 2 is a schematic side sectional view showing another embodiment of the apparatus
for practicing the printing process according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0008] In the printing process according to the present invention, as specifically described
hereinafter, there is used a solid ink which is solid at room temperature (generally,
20 - 30 °C). The solid ink used in the present invention may include an ink in the
form of powder.
[0009] Referring to Fig. 1, a solid ink 2 contained in an ink container (or tank) 2 is moved
toward a plate cylinder 9 by means of rollers 3 - 8 respectively rotating in the direction
of arrows shown in Fig. 1, and supplied to a plate 10 disposed on the plate cylinder
10. As the solid ink 2 is conveyed from the roller 4 to the roller 8, the solid ink
2 disposed on the roller is gradually converted into a thin layer form. Accordingly,
the amount of the ink supplied to the plate 10 may suitably be controlled by regulating
the number of such rollers 4 - 8. Examples of the material constituting the rollers
3 - 8 may include metal, resin, elastomer such as rubber, etc. Among these, elastomer
is particularly preferred.
[0010] Above the rollers 3 - 8, a heating device 11 is disposed as desired. In the process
of conveying the solid ink 2 from the ink container 1 to the plate 10, the solid ink
2 is converted into a liquid form (i.e., supplied with an adhesiveness to the plate
10), e.g., by heating it up to a temperature of the softening point thereof or higher.
As a result, the liquefied ink is supplied to the plate 10.
[0011] More specifically, the thus liquefied ink may preferably have an adhesiveness as
follows.
[0012] On the surface of the liquefied ink, a 0.1 mm - thick aluminum foil of 5 cm x 5 cm
in size is, after being accurately weighed, placed gently and is left standing as
it is for 1 min. in an environment of a moisture of 60 %. Then, the aluminum foil
is gently peeled off from the surface of the ink and then quickly weighed accurately
to measure the increase in weight of the aluminum foil. Through the measurement, the
liquefied ink used in the present invention should preferably show a weight increase
of the aluminum foil of 20 mg or more, more preferably 50 mg or more.
[0013] Referring to Fig. 1, the heating device 10 may be known one such as an infrared lamp,
a resistor capable of generating heat due to current conduction therethrough. Instead
of the heating device 11 disposed above the rollers 3 - 8, heating devices (not shown)
may be disposed inside the rollers 3 - 8.
[0014] The liquefied ink is applied onto the plate 10 by means of the roller 8, and the
thus applied ink is then transferred to a blanket cylinder 12 to form an ink pattern
corresponding to the pattern of the plate 10, as the plate cylinder 9 rotates. the
plate 10 may be known one. Example thereof may include, e.g., a plate for offset printing,
a plate for gravure printing, a relief, etc.
[0015] Below the blanket 12; an impression cylinder 13 is disposed opposite thereto. A transfer-receiving
paper 16, (i.e., medium to be recorded) 16 is supplied to the nip portion 17 between
the impression cylinders 13 and the blanket 12 in synchronism with the ink pattern
formed on the blanket 12. A large number of sheets of the transfer-receiving paper
are stored in a reservoir 14 and they are sequentially sent out to a conveying path
15.
[0016] The transfer-receiving paper 16 is moved by the rotation of the blanket 12 and the
impression cylinder 13, and contacts the ink pattern formed on the blanket 12 at the
nip portion 17, whereby the ink pattern is transferred to the transfer-receiving paper
16. The transfer-receiving paper 16 onto which the ink pattern is transferred is discharged
from the nip portion 17, and falls into a tray 18.
[0017] In the present invention, the blanket 12 is omissible in some cases. In such case,
an ink pattern formed on the plate 10 may be transferred to the transfer-receiving
paper 16 directly. However, the blanket 12 may preferably be disposed, because the
abrasion of the plate 10 due to the transfer-receiving paper 16 can be prevented,
and an image having the same pattern as that of the plate 10 can be obtained on the
transfer-receiving paper 16. The material constituting the plate cylinder 9, blanket
12 and impression cylinder 13 may be metal, resin, an elastomer such as rubber, etc.
[0018] Hereinbelow, the solid ink used in the present invention is described in more detail.
[0019] The solid ink used in the present invention may be either a material in the form
of a block or mass having certain dimensions, or a material in the form of powder.
More specifically, the solid ink may preferably be a powder material (i.e., a group
of particles having a particle size of 1 mm or smaller), or a block material which
has a shape-retaining property under ordinary conditions (i.e., 1 atmosphere, 25 °C,
relative humidity of 60 %). It is further preferred that the solid ink does not have
an adhesiveness.
[0020] In the present invention, the above-mentioned shape-retaining property may for example
be evaluated in the following manner.
[0021] A solid ink in the form of a block having a volume of 1 cm³ (1 cm x 1 cm x 1 cm)
is caused to stand still on a flat floor (e.g., the surface of a plate of stainless
steel) under the condition of 1 atm. for one hour. Thereafter, the maximum height
of the block counted from the floor surface (i.e., shape-retaining height) is measured.
In the present invention, the above-mentioned shape-retaining height may preferably
be 0.9 cm or larger, because such solid ink has a high shape-retaining property.
[0022] In the present invention, the above-mentioned adhesiveness may for example be evaluated
in the following manner.
[0023] An aluminum foil having a thickness of 0.1 mm is caused to stand still on a solid
ink to be evaluated for 5 sec. or more. Thereafter, the aluminum foil is peeled from
the solid ink. In such measurement, the solid ink used in the present invention may
preferably show a non-adhesiveness such that the solid ink is not substantially attached
to the above-mentioned aluminum foil (i.e., substantial attachment thereof is not
confirmed when observed with the naked eye).
[0024] More specifically, the solid ink at room temperature may preferably have a non-adhesiveness
as follows.
[0025] On the surface of the solid ink, an 0.1 mm - thick aluminum foil of 5 cm x 5 cm in
size is, after being accurately weighed, placed gently and is left standing as it
is for 1 min. in an environment of a temperature of 25 °C and a moisture of 60 %.
Then, the aluminum foil is gently peeled off from the surface of the ink and then
quickly weighed accurately to measure the increase in weight of the aluminum foil.
Through the measurement, the solid ink used in the present invention should preferably
show a weight increase of the aluminum foil of 10 mg or less, more preferably 2 mg
or less.
[0026] In an embodiment of the present invention wherein the solid ink is in the form of
powder, particles constituting the solid ink may preferably have a volume-average
particle size of 0.1 - 1,000 microns, more preferably 10 - 100 microns. If the volume-average
particle size is smaller than 0.1 micron, the fluidity of the ink is undesirably too
low. On the other hand, the volume-average particle size is larger than 1,000 microns,
the resultant image quality undesirably decreases. In the present invention, the above
volume-average particle size may be measured by means of a Coulter counter with a
100 microns - aperture.
[0027] The particles constituting the solid ink in the form of powder may be microcapsules
comprising a core material and a shell material. In such case, the core of the microcapsule
can also be a liquid material. Further, when a tacky solid material is converted into
a microcapsule form by coating it with a shell material, the handling thereof becomes
very easy.
[0028] In a case where a block having certain dimensions (i.e., a material other than powder)
is used as the solid ink, it is preferred to keep the ink contained in the ink container
1 in a liquid state by heating the ink container 1.
[0029] Further, as shown in Fig. 2, the solid ink 2 may be shaped into a bar form and used
by encasing it in a case 20. In the embodiment as shown in Fig. 2, the solid ink 2
in the bar form may continuously be pushed toward the roller 3 by means of a spring
21, etc., so that it may be applied onto the surface of the roller 3 along with the
rotation of the roller 3. In such case, the ink container 1 may be omitted.
[0030] In an embodiment wherein the solid ink 2 comprises microcapsules comprising a liquid
core material, the heating means 11 is omissible. In such case, the microcapsules
may be ruptured by the pressure applied between the rollers 3 - 8, whereby the solid
ink 2 is liquefied.
[0031] The solid ink (or the shell material in the case of the solid ink comprising microcapsules)
may preferably have a softening point of 40 - 150 °C, more preferably 50 - 120 °C,
according to the ring and ball method (JIS K 2531).
[0032] The solid ink (or the core material in a case where the solid ink comprises microcapsules)
used in the present invention may preferably be a mixture comprising a wax and a colorant
contained therein; or a gel, in a broad sense, comprising a liquid dispersion medium
and a crosslinked substance impregnated therewith; etc.
[0033] Examples of the wax may include: natural waxes such as whale wax, beeswax, lanolin,
carnauba wax, candelilla wax, montan wax, ceresin wax and the like; petroleum waxes
such as paraffin wax and microcrystalline wax; synthetic waxes such as oxidized wax,
ester wax, low-molecular weight polyethylene, Fischer-Tropsch wax and the like; etc.
[0034] In the present invention, various known dyes or pigments may be used as the colorant.
Specific examples of such colorant may include known dyes or pigments such as carbon
black, Nigrosin dyes, lamp black, Sudan Black SM, Fast Yellow G, Benzidine Yellow,
Pigment Yellow, Indo Fast Orange, Irgadine Red, Paranitroaniline Red, Toluidine Red,
Carmine FB, Permanent Bordeaux FRR, Pigment Orange R, Lithol Red 20, Lake Red C, Rhodamine
FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue, Pigment Blue, Brilliant
Green B, Phthalocyanine Green and Oil Yellow GG. These dyes or pigments may be used
singly or a combination of two or more species as desired. The colorant may preferably
be used in an amount of 0.1 - 40 wt. %, more preferably 1 - 20 wt. %, based on the
total weight of the ink.
[0035] In a case where the solid ink comprises a wax and a colorant contained therein, an
organic solvent may also be contained in the non-microcapsular solid ink. In such
case, the organic solvent content may preferably be 50 wt. % or less, more preferably
30 wt. % or less, in view of the storability of the ink.
[0036] As described above, the solid ink may also be a gel, in a broad sense, comprising
a liquid dispersion medium and a crosslinked substance impregnated therewith.
[0037] Herein, the "crosslinked substance" refers to a single substance which per se can
assume a crosslinked structure, such as those generally known as a thickness or a
telling agent, or a mixture of a substance capable of assuming a crosslinked structure
with the aid of an additive such as a crosslinking agent for providing a crosslinking
ion such as borate ion, and the additive. Further, the term "crosslinked structure"
refers to a three-dimensional structure having a crosslinkage or crosslinking bond.
The crosslinkage may be composed of any one or more of covalent bond, ionic bond,
hydrogen bond and van der Waal's bond, but may preferably be composed of ionic bond
and/or hydrogen bond in order to satisfy the above-mentioned fluidity and liquid dispersion
medium-retaining property of the ink in combination. More specifically, the crosslinked
structure may be any one of a network, a honeycomb, a helix, etc., or may be an irregular
one.
[0038] Examples of the crosslinked substance for providing the above-mentioned gel may include:
natural polymers including plant polymers such as guar gum, locust bean gum, gum arabic,
tragacanth, carrageenah, pectin, mannan, and starch; microorganism polymers such as
xanthane gum, dextrin, succinoglucan, and curdran; animal polymers such as gelatin,
casein, albumin, and collagen; semi-synthetic polymers including cellulose polymers
such as methyl cellulose, ethyl cellulose, and hydroxyethyl cellulose, starch polymers
such as soluble starch, carboxymethyl starch, methyl starch; alginic acid polymers
such as propylene glycol alginate, and alginic acid salts; and other semi-synthetic
polymers such as derivatives of polysaccharides; synthetic polymers including vinyl
polymers such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether,
carboxyvinyl polymer, and polysodium acrylate; and other synthetic polymers such as
polyethylene glycol, and ethylene oxide-propylene oxide block copolymer. These polymers
may be used singly or in mixture of two or more species, as desired.
[0039] In the present invention, the above-mentioned crosslinking agent may be a compound
containing aluminum, titanium, boron, etc. The crosslinking agent may preferably be
used in an amount of 20 wt. % or less based on the weight of the crosslinked substance.
[0040] The liquid dispersion medium constituting the gel composition in combination with
the above-mentioned crosslinked substance may preferably be a less vaporizable liquid,
in view of the ink storability and environmental sanitation. More specifically, there
may preferably used a liquid having a (saturation) vapor pressure of 15 mm Hg or below,
more preferably 1 mm Hg or below, particularly preferably 0.1 mm Hg or below at 20
°C, in view of less vaporization.
[0041] Examples of such liquid dispersion medium may include: polyhydric alcohols such as
ethylene glycol, propylene glycol, sorbitol, mannitol, diethylene glycol, triethylene
glycol, tetraethylene glycol, polyethylene glycol and glycerin; glycol ethers such
as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene
glycol monobutyl ether; nitrogen-containing compounds such as triethanolamine, formamide,
dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and 1,3-dimethylimidazolidinone.
the content of the liquid dispersion medium may preferably be 90 wt. % or less, more
preferably 60 wt. % or less, based on the total weight of the solid ink.
[0042] The solid ink may preferably be a gelatin gel containing gelatin in an amount of
5 - 50 wt. %, as the above-mentioned crosslinked substance, in view of printability;
supercooling property, etc., because such gel may shown in temperature at a relatively
low a large change in adhesiveness corresponding to a small difference temperature.
In a case where the above-mentioned gelatin gel is used, the solid ink may preferably
contain water in view of solubility and stability thereof. More preferably, the solid
ink may contain a liquid dispersion medium comprising a mixture of water and a polyhydric
alcohol, in view of the stability.
[0043] In a case where the solid ink comprises microcapsules, the shell material constituting
them may preferably be polyamide such as nylon, gelatin, urea-formalin resin, melamine-formalin
resin, polyurethane, etc. When the core material comprises a liquid, the liquid may
preferably be alkylnaphthalene, biphenyl derivatives, linseed oil, chlorinated paraffin,
etc.
[0044] The amount of a colorant contained the ink may preferably be 0.5 - 40 wt. %, more
preferably 1 - 20 wt. %, based on the total weight of the ink (or the core material
in the case of the microcapsular ink).
[0045] In order to form microcapsules, there may be used known microencapsulation techniques
such as the in-situ polymerization method, the interfacial polymerization method,
and the orifice method.
[0046] As described hereinabove, according to the present invention, there is provided a
printing process wherein a solid ink which is solid at room temperature is liquefied
to effect printing. According to the printing process of the present invention, it
is very easy to handle the ink and the frequency of staining of clothes or hands is
very low. Further, the printing machine can be operated immediately, even after it
is left standing for a long time. As a result, the operability of the printing machine
may be enhanced and the maintenance thereof becomes easier.
[0047] Hereinbelow, the present invention will be explained in further detail with reference
to Examples.
Example 1
Liquid A
[0048]
Diisopropylbiphenyl |
20 wt. parts |
|
Coronate L*1 (mfd. by Nihon Polyurethane K.K.) |
3 wt. parts |
Ethyl acetate |
6 wt. parts |
Macrolex Red 5B (mfd. by Bayer) |
0.2 wt. parts |
*1: Tri-functional isocyanate obtained by reacting 1 mole of trimethylolpropane with
3 moles of tolylene diisocyanate. |
[0049] The above components were sufficiently mixed to prepare a liquid
A.
Liquid B
[0050]
Colloidal Silica RA200-5 *2 |
0.6 wt. parts |
Water |
120 wt. parts |
*2: Product obtained by treating 100 wt. parts of Aerosil 200 (mfd. by Nihon Aerosil
K.K.) with 5 wt. parts of aminopropyltriethoxysilane. |
[0051] The above components were sufficiently mixed to prepare a liquid
B.
[0052] The liquid
B was mixed with the above liquid
A, and subjected to mixing by means of a homomixer at 7,000 rpm for 30 min. Then, the
mixture was heated up to 60 °C, subject to mixing at 200 rpm for three hours and subjected
to filtration and drying, thereby to prepare a solid ink in a powder form comprising
microcapsules having a volume-average particle size of 11 microns.
[0053] By using the thus prepared solid ink, printing was effected by means of a printing
machine as shown in Fig. 1.
[0054] Referring to Fig. 1, a plate 10 was prepared in the following manner. A paint comprising
a fluorine-containing polymer (trade name: FC-721, Sumitomo Three-Emu K.K.) as an
ink-adherent liquid was applied onto a 50 micron-thick polyimide film to form an about
3 microns-thick paint layer. Then, a desired pattern was formed on the fluorine-containing
polymer paint layer by electrophotography by using toner particles which had a volume-average
particle size of 4.4 microns and predominantly comprised a styrene-acrylic resin
and carbon black. The above prepared plate 10 was wound about an aluminum plate cylinder
9 having a diameter of 20 cm.
[0055] Referring again to Fig. 1, the above-mentioned solid ink 2 was charged in an ink
tank 1 and printing was effected by rotating rollers 3 - 8 so as to rotate the above-mentioned
plate cylinder 9 at 10 rpm. The solid ink was crushed by the rollers 3 - 8 and liquefied,
and was applied onto the plate 10. Then, the ink applied onto the plate 10 was transferred
to a transfer-receiving paper 16 by the medium of a blanket cylinder 12 having a diameter
of 20 cm. As a result, the liquefied ink penetrated into the transfer-receiving paper
16 thereby to provide a good image which was faithful to the original pattern formed
on the plate 10.
[0056] After the printing, the ink disposed on the rollers 3 - 8 was removed, and the printing
machine was left standing for 10 days while retaining the ink 2 in the ink tank 1
as such. Thereafter, printing was again effected whereby the same images as described
above were obtained.
Example 2
Liquid A
[0057]
Diisopropylnaphthalene |
80 wt. parts |
Adipic acid chloride |
12 wt. parts |
Terephthalic acid chloride |
4 wt. parts |
Kayaset Blue (mfd. by Nihon Kayaku K.K.) |
2.2 wt. parts |
Dioctyl phthalate |
10 wt. parts |
Liquid B
[0058]
Colloidal silica RA 200-5 (the same as in Example 1) |
1.2 wt. parts |
Water |
140 wt. parts |
Liquid C
[0059]
Diethylenetriamine |
6 wt. parts |
Tri (γ-aminopropyl) methane |
10 wt. parts |
Water |
40 wt. parts |
[0060] The above components were respectively sufficiently mixed to prepare a liquid
A, a liquid
B and a liquid
C.
[0061] The liquid
B was mixed with the above liquid
A, and subjected to mixing by means of a homomixer at 8,500 rpm for 15 min. Then, the
above liquid
C was added to the resulted mixture and heated up to 40 °C, stirred for three hours
at 100 rpm and subjected to filtration and drying, thereby to prepare a solid ink
in a powder form comprising microcapsules, having a volume-average particle size of
16 microns.
[0062] By using the thus prepared solid ink, printing was effected in the same manner as
in Example 1. As a result, good images were obtained similarly as in Example 1.
[0063] The printing machine was left standing for 10 days in the same manner as in Example
1, and thereafter printing was effected. As a result, there were obtained good images
which were substantially the same as mentioned above (i.e., before the printing machine
was left standing).
Example 3
[0064] A solid ink capable of liquefying under heating and pressure was prepared in the
following manner.
Paraffin wax 130 °F (mfd. by Nihon Seiro K.K, softening point = 54 °C) |
100 wt. parts |
Carbon black (mfd. by Cabot Co.) |
5 wt. parts |
[0065] The above components were mixed at 60 °C for three hours by means of an attritor,
thereby to prepare an ink which was solid at room temperature. when the thus prepared
ink was subjected to the measurement of the shape-retaining height and the adhesion
to an aluminum foil, in the above-described manner, it showed a shape-retaining height
of 1.0 cm and substantially no adhesion.
[0066] The thus prepared ink was subjected to printing by means of the printing machine
in the same manner as in Example 1 except that the ink 2 was heated up to 70 °C in
the ink tank 1 and an infrared lamp 11 was disposed above the rollers 4 - 8 so that
the roller surfaces were heated up to 65 °C to liquefy the ink disposed on the rollers.
[0067] In such state, the heating due to the infrared lamp was stopped and left standing
for 10 days. Thereafter, the ink was again heated by the infrared lamp and the rollers
of the printing machine was operated, whereby the same liquefied ink layer as described
above was obtained. Further, such ink layer was applied onto a plate 10 and transferred
to a transfer-receiving paper, whereby good images were obtained.
Example 4
[0068]
Ethylene glycol (vapor pressure = 0.05 mmHg at 20 °C) |
120 wt. parts |
Water (vapor pressure = 17.5 mmHg at 20 °C) |
40 wt. parts |
Gelatin (trade name: S2088, mfd. by Nippi Gelatin Kogyo K.K.) |
40 wt. parts |
Carbon black (mfd. by Cabot. Co., USA) |
6 wt. parts |
Butyl para-hydroxybenzoate (antiseptic) |
1 wt. parts |
[0069] The above components were mixed at 70 °C to prepare an ink which showed a softening
point of about 45 °C, a shape-retaining height of 1.0 cm and substantially no adhesion
to an aluminum foil.
[0070] Referring to Fig., the thus prepared ink was heated at 70 °C in the ink tank 1 and
subjected to printing in the same manner as in Example 3 except that the surfaces
of rollers 3 - 8 were heated at 60 °C and a plate 10 corresponding to a solid image
pattern was used. As a result, a uniform solid image was obtained on plain paper.
This image was sufficiently fixed to the paper so that the offset thereof did not
occur even when the recorded paper was superposed on another paper.
[0071] Then, the printing machine supplied with the ink was as such left standing at room
temperature (23 - 25 °C) for 10 days. Thereafter, printing was effected in the same
manner as described above, whereby the same solid image as mentioned above was obtained.
Example 5
[0072]
Ethylene glycol |
1440 wt. parts |
Water |
360 wt. parts |
Butyl para-hydroxybenzoate (antiseptic) |
8 wt. parts |
|
Polyvinyl alcohol (trade name: Gohsenol GL-0.3, mfd. by Nihon Gosei Kagaku Kogyo K.K.) |
360 wt. parts |
Borax (decahydrate) (crosslinking agent) |
14 wt. parts |
0.1N NaOH |
14 wt. parts |
Carbon black (mfd. by Cabot Co., USA) |
100 wt. parts |
[0073] The above components were mixed at 70 °C to prepare an ink which showed a softening
point of about 55 °C, a shape-retaining height of 0.98 cm and substantially no adhesion
to an aluminum foil.
[0074] The thus prepared ink was subjected to printing in the same manner as in Example
4, whereby good printed matter the same as in Example 4 was obtained.
[0075] Then, the printing machine was left standing for 10 days in the same manner as in
Example 4. Thereafter, printing was effected in the same manner as described above,
whereby the same solid image as mentioned above was obtained.
Example 6
[0076] An ink was prepared in the same manner as in Example 4 except that 12 wt. parts of
a reactive dye (trade name: Red E-S3B, mfd. by Nihon Kayaku K.K.) was used instead
of the carbon black used in Example 4. This ink showed a shape-retaining height of
0.98 cm and substantially no adhesion to an aluminum foil.
[0077] The thus prepared ink was subjected to printing in the same manner as in Example
4, whereby good printed matter the same as in Example 4 was obtained.
[0078] Then, the printing machine was left standing for 10 days in the same manner as in
Example 4. Thereafter, printing was effected in the same manner as described above,
whereby the same solid image as mentioned above was obtained.