JP2002178624A - Method for ink jet recording and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for ink jet recording capable of obtaining excellent image quality irrespective of a type of a recording medium and an image forming apparatus. SOLUTION: The method for ink jet recording comprises the steps of discharging the ink containing a color material and a solvent toward a surface of the recording medium, and forming the image by the ink on the surface of the medium. The method further comprises a powder scattering step of scattering a powder capable of separating the color material and the solvent in the ink toward the surface of the medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet recording method and an image forming apparatus.

[0002]

2. Description of the Related Art An ink jet printer discharges a liquid or a molten solid ink from a nozzle, a slit, a porous film, or the like, and performs recording on paper, cloth, film, or the like. It is known to have the advantage of: Then, a piezo ink jet system using a piezoelectric element, a thermal ink jet system in which recording is performed by applying thermal energy to ink, and the like have been developed, and an increase in printing speed and an improvement in image resolution have been achieved.

[0003] However, the piezo ink jet system and the thermal ink jet system have the advantages that the printing speed can be increased and the resolution can be improved. However, when plain paper is used as a recording medium, the printing characteristics deteriorate, and Bleeding in single color printing (feathering), so-called intercolor bleeding which is a problem when performing color printing using a plurality of color inks, and the paper warps with the surface on which the image is printed on the inside. In some cases, such problems as curling and so-called "cuckling" in which the shape of paper is deformed into a wave shape may occur, and it has been difficult to obtain excellent image quality regardless of the type of recording medium.

On the other hand, for example, Japanese Patent Application Laid-Open No. H11-188855
In Japanese Patent Application Laid-Open Publication No. H10-157, after forming an image with a recording liquid, a glossy paper is used as a recording medium, particularly, by supplying powder having a porous structure to an image portion to suppress the image from touching another object. An image forming apparatus that improves image quality in such a case has been proposed.

[0005]

SUMMARY OF THE INVENTION However, the present inventors have disclosed that the image forming apparatus described in Japanese Patent Application Laid-Open No. H11-188855 discloses that a print image formed on a recording medium is printed on another recording medium. Although it is possible to prevent a decrease in image quality due to contact with other objects, the above-described feathering that occurs in a print image itself formed on a recording medium,
Since it is not configured from the viewpoint of sufficiently preventing defects such as bleeding between colors, generation of curls and cuckles, occurrence of these defects cannot be essentially and sufficiently prevented, and excellent image quality can be obtained. There was a problem that it could not be done, and it was found that it was still not enough.

[0006] In particular, the image forming apparatus described in Japanese Patent Application Laid-Open No. H11-188855, when plain paper is used as a recording medium, sufficiently prevents problems such as feathering, bleeding between colors, curling and cuckling. There was a problem that it was not possible to prevent this and to obtain excellent image quality.

That is, an ink jet ink recording method capable of obtaining excellent image quality irrespective of the type of recording medium and an image forming apparatus having a structure operating based on this method have not been obtained until now.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to provide an ink jet recording method and an image forming apparatus capable of obtaining excellent image quality regardless of the type of recording medium. And

[0009]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, before discharging the ink, the coloring material and the solvent contained in the ink on the surface of the recording medium were discharged. By spraying a predetermined amount of powder capable of separating the ink, or by spraying a predetermined amount of the above powder immediately after the ink lands on the surface of the recording medium, feathering, color The present inventor has found that it is possible to sufficiently prevent the occurrence of problems such as interstitial bleeding, curling, and cuckling, and arrived at the present invention.

That is, the ink jet recording method of the present invention is an ink jet recording method for ejecting an ink having a coloring material and a solvent toward a surface of a recording medium and forming an image with the ink on the surface of the recording medium. A powder spraying step of spraying powder capable of separating a coloring material and a solvent in the ink toward the surface of the recording medium.

Here, in the present invention, "powder capable of separating a coloring material in an ink from a solvent" refers to a powder having a property of absorbing the solvent in the ink or a coloring material in the ink. 3 shows a powder having a property of causing agglomeration.

As described above, the ink jet recording method of the present invention sufficiently prevents the occurrence of defects such as feathering, intercolor bleeding, curling and cuckling by spraying the powder toward the surface of the recording medium. It is possible to do. Although it is not clear why the spraying of the powder improves the image quality, in the case of a powder having a property of absorbing the solvent in the ink, the powder is dispersed in the ink. It is considered that the absorption of the ink prevents the ink that has landed on the recording medium from spreading in the surface direction of the recording medium. Further, in the case of a powder having a property of aggregating the coloring material in the ink, it is considered that the coloring material is agglomerated when the ink and the powder come into contact on the recording medium. Therefore, the solvent components other than the coloring material in the ink are absorbed by penetrating into the recording medium, but the coloring material is separated from the solvent component due to agglomeration and is not absorbed inside the recording medium, but is absorbed on the surface of the recording medium. It is thought that it is because it remains.

In the ink jet recording method of the present invention, it is preferable that the ink is ejected onto the surface of the recording medium after the powder is dispersed on the surface of the recording medium in the powder dispersing step. In this way, before the ink lands on the surface of the recording medium, by spraying the powder on the surface in advance, it is possible to reliably prevent the occurrence of the above-described problems such as feathering, intercolor bleeding, curling, and cuckling. And it can be easily prevented.

[0014] Contrary to the above, powder may be ejected after the ink is ejected onto the surface of the recording medium, but in this case, the ink that has landed on the surface of the recording medium will be ejected in the surface direction. The composition of the ink, the amount of ink supplied, and the amount of ink that spread to the extent that feathering or intercolor bleeding occurs or do not excessively penetrate inside the recording medium to the extent that the optical density of the printed image is insufficient. In consideration of the composition of the recording medium, the conveyance speed of the recording medium, and the like, the timing of powder spraying from a predetermined powder supply means for ink ejection and the supply amount thereof may be controlled.

Further, the recording medium in the present invention is not particularly limited, and for example, plain paper, OHP sheet, glossy paper, coated paper, film, cloth and the like can be used. Among these, paper is preferred because the ink can be used irrespective of water-based ink or oil-based ink, and plain paper is more preferred among the papers. As plain paper, for example, L
Paper, Multi-ace paper, M paper, P paper, S paper, R paper, WR
Paper, WR100 paper, Green100 paper (all manufactured by Fuji Xerox Office Supply Co., Ltd.) and the like.

Further, the image forming apparatus of the present invention discharges ink having a coloring material and a solvent toward a surface of the recording medium conveyed by the conveying means for conveying the recording medium, and discharges the recording medium. Image forming means for forming an image by ink on the surface of the image forming apparatus,

Powder supply means for spraying powder capable of separating a colorant and a solvent in the ink toward the surface of the recording medium conveyed by the conveyance means;

The powder supply means is disposed upstream of the image forming means with respect to the direction of conveyance of the recording medium by the conveyance means.
The image forming means forms an image with ink on the surface of the recording medium after the powder is sprayed by the powder supply means.

As described above, the image forming apparatus of the present invention includes the powder supply means for spraying the powder before the ink lands on the recording medium. Since it has a configuration that operates based on the method, it is possible to sufficiently prevent the occurrence of problems such as feathering, bleeding between colors, curling, and cuckling. Therefore, this image forming apparatus can obtain a printed image having excellent image quality.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the ink jet recording method of the present invention will be described in detail. As described above, the ink jet recording method of the present invention includes a powder spraying step of spraying powder capable of separating a colorant and a solvent in ink toward a surface of a recording medium. Then, after the powder is sprayed on the surface of the recording medium in the powder spraying step, the ink is ejected onto the surface of the recording medium.

As described above, in the ink jet recording method of the present invention, it is preferable that the ink is ejected onto the surface of the recording medium after the powder is dispersed on the surface of the recording medium in the powder dispersing step. However, ink that has landed on the surface of the recording medium spreads to the extent that feathering or intercolor bleeding occurs in the surface direction, or excessively penetrates into the recording medium to such an extent that the optical density of the printed image becomes insufficient. If it is possible to precisely control the timing and amount of powder spraying from a predetermined powder supply means with respect to the ejection of ink so as not to cause the ink to be ejected, the ink is ejected onto the surface of the recording medium. The powder may be injected later.

The method of applying the powder in the powder dispersing step of the present invention is not particularly limited, and a known powder dispersing method can be used. Examples of such a powder spraying method include a fluid immersion method, an electrostatic fogging method, a thermal spraying method, an electrostatic dry spraying method, and a spraying method. It is also possible to spray the powder using a container or the like that has an opening provided with an openable lid and that can store the powder inside. At this time, for example, the cover is opened only when passing through the recording medium, the powder is sprayed on the recording medium, the cover is closed when not in use, and control means for adjusting the powder so as not to be sprayed is provided. Can be precisely controlled.

The ink jet recording method of the present invention is not particularly limited as long as it has the above-mentioned powder dispersing step, and the image forming method and ink discharging method are not particularly limited. A known method such as a thermal ink jet method may be used. However, when an aqueous ink is used as the ink, it is preferable to employ a thermal ink jet recording method from the viewpoint that there is an effect of improving image quality by preventing the occurrence of bleeding and intercolor bleeding. Although the cause has not been clarified, in the case of the thermal ink jet recording method, the viscosity of the ink is reduced by heating at the time of ejection, but after landing on the recording medium, the viscosity sharply decreases with the decrease in temperature. It is thought that the effect of suppressing the spread of the ink on the recording medium works. On the other hand, when an oil-based ink is used as the ink, it is preferable to adopt a piezo inkjet method from the viewpoint of ink ejection properties.

When a thermal ink jet recording method is employed in the ink jet recording method of the present invention, it is preferable to form one drop by applying a plurality of pulses to the ink. By doing so, it is possible to improve the ejection stability of the ink from the nozzle,
Furthermore, it is possible to suppress the occurrence of scorching (kogation) of the ink on the heater.

Further, in the ink jet recording method of the present invention, the drop amount of the ink
L, preferably 5 to 18 pL, more preferably 10 to 16 pL. The contact angle of the ink on the recording medium changes depending on the amount of ink drop, and the larger the amount of ink drop, the smaller the contact angle. Therefore, by controlling the drop amount of the ink within the range of 20 pL or less, it is possible to appropriately control the permeation of the ink into the recording medium and the diffusion toward the surface of the recording medium to obtain a sufficient quick drying property when printing. It can be easily adjusted to a level at which a sufficient optical density can be obtained. Here, if the drop amount of the ink exceeds 20 pL, the bleeding of the print tends to be remarkable.

Here, the ink used in the ink jet recording method of the present invention is not particularly limited, and may be an aqueous ink or an oil ink. And
From the viewpoint of separating the colorant and the solvent in the ink, the powder used in the present invention is selected from those having preferable characteristics depending on whether the ink used is an aqueous ink or an oil-based ink.

First, the case where an aqueous ink is used in the ink jet recording method of the present invention will be described. The coloring material contained in the aqueous ink used in the present invention is not particularly limited, and for example, pigments, dyes and the like can be used.

When a pigment is used, either an organic pigment or an inorganic pigment can be used. For example, black pigment and cyan pigment, magenta pigment, in addition to the three primary color pigments yellow pigment, red, green, blue, brown, white and other specific color pigments, gold, silver and other metallic luster pigments, colorless or A light-colored extender, a plastic pigment, or the like may be used. Also, for the present invention, a newly synthesized pigment may be used.

As the black pigment, furnace black,
And carbon black pigments such as lamp black, acetylene black, and channel black. Further, as the cyan pigment, CI Pigment Blue-1, -2, -3, -1
5, -15: 1, -15: 2, -15: 3, -15: 4, -16, -22, -60 and the like. Further, as a magenta color pigment, CI Pigment
Red -5, -7, -12, -48, -48: 1, -57, -112, -122, -12
3, -146, -168, -184, -202 and the like. In addition, as a yellow pigment, CI Pigment Yellow -1, -2, -3,
-12, -13, -14, -16, -17, -73, -74, -75, -83, -9
3, -95, -97, -98, -114, -128, -129, -138, -151, -15
4 and the like.

Specifically, for example, Raven7000, Raven57
50, Raven5250, Raven5000 ULTRAII, Raven 3500, Rave
n2000, Raven1500, Raven1250, Raven1200, Raven1190
ULTRAII, Raven1170, Raven1255, Raven1080, Raven106
0 (all manufactured by Columbian Carbon Co., Ltd.), Regal400R, Regal3
30R, Regal660R, Mogul L, Black Pearls L, Monarch 7
00, Monarch 800, Monarch 880, Monarch 900, Monarch
1000, Monarch 1100, Monarch 1300, Monarch 1400 (all manufactured by Cabot Corporation), Color Black FW1, ColorBlack FW2,
Color Black FW2V, Color Black 18, Color Black FW2
00, Color Black S150, Color Black S160, Color Blac
k S170, Printex35, Printex U, Printex V, Printex14
0U, Printex140V, Special Black 6, Special Black 5
, Special Black 4A, Special Black4 (from Degussa), No.25, No.33, No.40, No.47, No.52, No.900, N
o.2300, MCF-88, MA600, MA7, MA8, MA100 (all manufactured by Mitsubishi Chemical Corporation) and the like.

In the present invention, a pigment which can be self-dispersed in water can be used as the pigment. Here, in the present invention, the “water-dispersible pigment” satisfies the condition based on the concentration of the pigment measured according to the procedure described below, and has a water-soluble functional group on the surface of the pigment. It refers to a pigment that has a group and can be stably dispersed in water without using a polymer dispersant. That is, first, a pigment is added to water so that water becomes 95% by mass and pigment becomes 5% by mass, and the pigment is dispersed in water using an ultrasonic homogenizer and left in a glass bottle for 24 hours. Next, one third of the total volume of the supernatant is collected from the obtained pigment dispersion. Then, the pigment concentration in the supernatant of the dispersion is measured, and when this pigment concentration is 98% or more with respect to the pigment concentration in the dispersion immediately after dispersion, the pigment is regarded as a self-dispersible pigment in water. . Such water-dispersible self-dispersible pigments are usually so-called pigments treated with an acid or base, a coupling agent, a polymer graft, a plasma,
It can be obtained by performing a surface modification treatment such as an oxidation / reduction treatment.

The pigment which can be self-dispersed in water is not particularly limited as long as it satisfies the above-mentioned conditions. For example, in addition to the pigment that has been subjected to a surface modification treatment on the pigment,
Cabot Cab-o-jet-200, Cab-o-jet-300, IJX-5
5, IJX-253, IJX-266, IJX-273, manufactured by Orient Chemical
Microjet Black CW-1, CW-2, or a commercially available self-dispersion pigment such as a self-dispersion pigment sold by Nippon Shokubai Co., Ltd. may be used. You may.

On the other hand, when a dye is used, a water-soluble dye,
Either an oil dye or a disperse dye may be used. Examples of the water-soluble dye include CI Direct Black -2, -4, -9,
-11, -17, -19, -22, -32, -80, -151, -154, -168,-
171, -194, -195, CI Direct Blue -1, -2, -6,-
8, -22, -34, -70, -71, -76, -78, -86, -112, -142,-
165, -199, -200, -201, -202, -203, -207, -218, -23
6, -287, -307, CI Direct Red -1, -2, -4, -8,-
9, -11, -13, -15, -20, -28, -31, -33, -37, -39, -5
1, -59, -62, -63, -73, -75, -80, -81, -83, -87, -9
0, -94, -95, -99, -101, -110, -189, -227, CI D
irect Yellow -1, -2, -4, -8, -11, -12, -26, -27,-
28, -33, -34, -41, -44, -48, -58, -86, -87, -88,-
132, -135, -142, -144, -173, CI Food Black -1,
-2, CI Acid Black -1, -2, -7, -16, -24, -26,-
28, -31, -48, -52, -63, -107, -112, -118, -119, -1
21, -156, -172, -194, -208, CI Acid Blue -1,-
7, -9, -15, -22, -23, -27, -29, -40, -43, -55, -5
9, -62, -78, -80, -81, -83, -90, -102, -104, -111,
-185, -249, -254, CI Acid Red -1, -4, -8, -1
3, -14, -15, -18, -21, -26, -35, -37, -52, -110,-
144, -180, -249, -257, -289, CIAcid Yellow -1,
-3, -4, -7, -11, -12, -13, -14, -18, -19, -23, -2
5, -34, -38, -41, -42, -44, -53, -55, -61, -71, -7
6, -78, -79, -122 and the like.

The content of the coloring material contained in the aqueous ink described above is 0.5 to 20 with respect to the total mass of the aqueous ink.
% By mass, and more preferably 1 to 10% by mass. When the content is less than 0.5% by mass, a tendency that a sufficient optical density cannot be obtained increases. On the other hand, if the content exceeds 20% by mass, it tends to be difficult to smoothly eject the ink onto a recording medium such as plain paper.

The water-soluble organic solvent contained in the ink-jet ink of the present invention is not particularly limited as long as it is water-soluble. For example, polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, alcohols, Sulfur-containing solvents, propylene carbonate, ethylene carbonate and the like can be used. Here, polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol,
Butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, glycerin and the like. Further, as polyhydric alcohol derivatives,
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, ethylene oxide adduct of diglycerin and the like. Can be Further, examples of the nitrogen-containing solvent include pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, and triethanolamine. In addition, as alcohols, ethanol, isopropyl alcohol,
Butyl alcohol, benzyl alcohol and the like. Furthermore, examples of the sulfur-containing solvent include thiodiethanol, thiodiglycerol, sulfolane, dimethyl sulfoxide and the like.

As the water-soluble organic solvent contained in the aqueous ink of the present invention, one kind of solvent may be used alone, or two or more kinds of solvents may be mixed and used as a mixed solvent. . Further, the content of the water-soluble organic solvent in the aqueous ink is preferably from 1 to 60% by mass, more preferably from 5 to 40% by mass, based on the total mass of the aqueous ink. When the content of the water-soluble organic solvent is less than 1% by mass, a tendency that a sufficient optical density cannot be obtained increases. On the other hand, when the content of the water-soluble organic solvent exceeds 60% by mass, the tendency of the aqueous ink on the recording medium to be insufficiently quick-drying is increased.

In the present invention, a polymer dispersant may be added to disperse the above-mentioned content in the aqueous ink. Examples of such a polymer dispersant include a nonionic compound, an anionic compound, a cationic compound,
Any of the amphoteric compounds may be used.

For example, an alkylene oxide adduct of a polyhydric alcohol may be used. Specifically, compounds obtained by adding an alkylene oxide group such as ethylene oxide, propylene oxide, or butylene oxide to a polyhydric alcohol such as ethanediol, propanediol, butanediol, hexanediol, glycerin, trimethylolpropane, or pentaerythritol. Is mentioned. More specifically, polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene-polyoxypropylene copolymer glycol, polyoxyethylene-polyoxybutylene copolymer glycol, and the like can be mentioned.

Further, a copolymer of a monomer having an α, β-ethylenically unsaturated group may be used as the polymer compound. Such monomers having an α, β-ethylenically unsaturated group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester , Vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, bismethacryloxyethyl phosphate, methacryloxyethyl phenylacid phosphate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, styrene, α- Styrene derivatives such as methylstyrene and vinyltoluene, vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives, alkyl acrylate, phenyl acrylate Ester, methacrylic acid alkyl esters, methacrylic acid phenyl ester, methacrylic acid cycloalkyl ester, crotonic acid alkyl ester, itaconic acid dialkyl esters, maleic acid dialkyl ester and the like.

The copolymer of a monomer having an α, β-ethylenically unsaturated group is a copolymer synthesized from at least one type of monomer having an α, β-ethylenically unsaturated group described above. Is mentioned. Specifically, polyvinyl alcohol, polyvinyl pyrrolidone, styrene-
Styrene sulfonic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer,
Vinyl naphthalene-methacrylic acid copolymer, vinyl naphthalene-acrylic acid copolymer, alkyl acrylate
-Acrylic acid copolymer, alkyl methacrylate-
Methacrylic acid, styrene-alkyl methacrylate
-Methacrylic acid copolymer, styrene-alkyl acrylate-acrylic acid copolymer, styrene-methacrylic acid phenyl ester-methacrylic acid copolymer, styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer and the like.

The weight average molecular weight of the polymer dispersant contained in the aqueous ink used in the present invention is 2,000 to 15,000.
And more preferably from 350 to 10,000. If the molecular weight of the polymer dispersant is less than 2,000, it tends to be difficult to stably disperse the pigment in the aqueous ink. On the other hand, when the weight average molecular weight exceeds 15,000, the viscosity of the water-based ink becomes high, and the tendency that the ejection property deteriorates increases.

The content of the high molecular compound contained in the aqueous ink used in the present invention is preferably 0.1 to 3% by mass based on the total mass of the ink.
The content is more preferably from 0.2 to 2.5% by mass.
More preferably, the content is 15 to 2% by mass. When the content of the polymer compound is less than 0.1% by mass, the occurrence of ink bleeding tends to be remarkable. On the other hand, when the content of the polymer compound exceeds 3% by mass, it tends to be difficult to smoothly eject the ink onto a recording medium such as plain paper.

In the present invention, the content of water contained in the aqueous ink is 14 to 9 with respect to the mass of the ink.
8.4% by mass, preferably 40 to 90% by mass
Is more preferable. If the water content is less than 14% by mass, the ink tends to be unable to be ejected smoothly from the nozzles. On the other hand, if the content of water exceeds 98.4% by mass, the tendency for long-term storage properties to decrease is increased.

Furthermore, the following additives may be added to the aqueous ink used in the present invention, if necessary, in addition to the components described above.

That is, for example, in order to control the ejection characteristics of ink or to improve long-term storage stability, polyethyleneimine is used.
Polyamines, polyvinylpyrrolidone, polyethylene glycol, ethyl cellulose, cellulose derivatives such as carboxymethyl cellulose, polysaccharides and derivatives thereof, other water-soluble polymers, acrylic polymer emulsions, polymer emulsions such as polyurethane emulsions, cyclodextrin, macrocyclic amines, Dendrimers, crown ethers, urea and its derivatives, acetamide and the like can be used. Further, in order to adjust conductivity and pH, compounds of alkali metals such as potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, triethanolamine, diethanolamine, ethanolamine, 2-amino-2- Nitrogen-containing compounds such as methyl-1-propanol, compounds of alkaline earth metals such as calcium hydroxide, acids such as sulfuric acid, hydrochloric acid, and nitric acid, and salts of strong acids and weak alkalis such as ammonium sulfate can be used. Furthermore,
pH buffer, antioxidant, fungicide, viscosity modifier, conductive agent,
An ultraviolet absorber, a chelating agent, and also a water-soluble dye, a disperse dye, an oil-soluble dye, and the like can be added.

In the present invention, when an image is formed using an aqueous ink having the above components, the powder (water, water-soluble organic solvent) in the aqueous ink is used as the powder to be sprayed on the recording medium in the powder spraying step. A powder having a property of absorbing or a powder having a property of aggregating the coloring material in the aqueous ink is used.

Examples of the powder having the property of absorbing the solvent in the aqueous ink include a water-absorbing polymer. As such a water-absorbing polymer, any of a natural gel and a synthetic gel may be used, and further, these natural gels and synthetic gels may be any of a nonionic compound, a cationic compound, and an anionic compound. Good. Above all, a partially crosslinked hydrophilic polymer is preferably used from the viewpoint of high solvent absorption ability and a large effect of improving image quality by preventing generation of intercolor bleeding.

Specific examples of the water-absorbing polymer include agarose, agaropectin, amylose, amylopectin,
Sodium alginate, propylene glycol alginate, ethyl hydroxyethyl cellulose, carrageenan, carboxymethyl cellulose, carboxymethyl starch, chitin, chitosan, glucomannan, keratin protein, collagen, schizophyllan, gelatin, cellulose, starch, polystyrene sulfonic acid, polyvinyl alcohol, polyvinyl pyrrolidone , Methylcellulose,
Hydroxyethyl cellulose, hyaluronic acid, bisacrylamide methyl ether, polyacrylamide, poly
-(2-acrylamido-2-methylpropanesulfonic acid), polyacrylic acid, poly- (N, N′-dimethylaminoethyl acrylate), sodium polyacrylate, cross-linked sodium polyacrylate, poly- (N -Isopropylacrylamide), polyamidine, polyisobutyllenmaleic acid copolymer, polyethyleneimine, polyethylene oxide, polyvinylpyridine and the like.

Among the above water-absorbing polymers, sodium alginate, ethyl hydroxyethyl cellulose, carrageenan, carboxymethyl cellulose, carboxymethyl starch, chitin, chitosan, cellulose, starch, polyvinyl alcohol, methyl cellulose, polyacrylamide, polyacrylic acid, sodium polyacrylate A crosslinked product of sodium polyacrylate, poly- (N-isopropylacrylamide) and the like are preferably used from the viewpoint that they have a high solvent-absorbing ability and have a large effect of improving image quality by preventing the occurrence of intercolor bleeding.

Examples of the powder having the property of aggregating the coloring material in the aqueous ink include the following electrolytes.
That is, lithium ions, sodium ions, alkali metal ions such as potassium ions and the like, aluminum ions, barium ions, calcium ions, copper ions, iron ions, magnesium ions, manganese ions,
Nickel ions, tin ions, titanium ions, polyvalent metal cations consisting of zinc ions and the like, anions derived from oxo acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, thiocyanic acid, acetic acid, oxalic acid, Examples include an anion derived from an organic carboxylic acid such as lactic acid, fumaric acid, fumaric acid, citric acid, salicylic acid, and benzoic acid, or a salt with an anion derived from an organic sulfonic acid. It is also possible to use a cationic electrolyte that becomes an organic cation by dissociation in water.

Specific examples of the above electrolyte include, for example,
1) Alkali metals such as lithium chloride, sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, sodium sulfate, potassium nitrate, sodium acetate, potassium oxalate, sodium citrate, potassium benzoate, etc. Salt, 2) aluminum chloride, aluminum bromide, aluminum sulfate, aluminum nitrate, sodium aluminum sulfate, potassium aluminum sulfate, aluminum acetate, barium chloride, barium bromide, barium iodide, barium oxide, barium nitrate, barium thioate, Calcium chloride, calcium bromide, calcium iodide, calcium nitrite, calcium nitrate, calcium dihydrogen phosphate, calcium thiocyanate, calcium benzoate, calcium acetate, calcium salicylate, tartar Calcium, calcium lactate, calcium fumarate, calcium citrate, copper chloride, copper bromide, copper sulfate, copper nitrate, copper acetate, iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, iron oxalate, lactic acid Iron, iron fumarate, iron citrate, magnesium chloride, magnesium bromide, magnesium iodide, magnesium sulfate, magnesium nitrate, magnesium acetate, magnesium lactate, manganese chloride, manganese sulfate, manganese nitrate, manganese dihydrogen phosphate, manganese acetate , Manganese salicylate, manganese benzoate, manganese lactate, nickel chloride, nickel bromide, nickel sulfate, nickel nitrate, nickel acetate, tin sulfate,
Examples thereof include salts of polyvalent metals such as titanium chloride, zinc chloride, zinc bromide, zinc sulfate, zinc nitrate, zinc thiocyanate, zinc acetate, calcium carbonate, magnesium carbonate and the like.

Specific examples of the cationic electrolyte include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, polyamines and the like. Ethylenepentamine, tetramethylammonium chloride, tetraethylammonium bromide, dihydroxyethylstearylamine, 2-heptadecenyl-hydroxyethylimidazoline, lauryldimethylbenzylammonium chloride, cetylpyridinium chloride, stearamidomethylpyridium chloride, diallyldimethylammonium chloride polymer, Diallylamine polymers, monoallylamine polymers and the like.

Among the above electrolytes, aluminum sulfate, calcium carbonate, calcium chloride, calcium nitrate, calcium acetate, magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium acetate, tin sulfate, zinc chloride, zinc nitrate, zinc sulfate, zinc acetate , Aluminum nitrate, monoallylamine polymer, diallylamine polymer, diallyldimethylammonium chloride polymer and the like are preferably used from the viewpoint that the pigment has a high coagulation ability and the effect of preventing image bleeding from occurring is greatly improved in image quality. Is done.

When the above-mentioned electrolyte is used as the powder, it is preferable to use one containing a polyvalent metal or a compound having a polarity opposite to the polarity of the surface functional group of the coloring material. Further, in addition to the above powder, inorganic fine particles such as silicon dioxide, titanium dioxide, talc (a hydrous silicate mineral of magnesium), and clay (a hydrous silicate mineral of a metal or the like) may be used as other additives. It is possible. When inorganic fine particles are used, the solvent in the ink is effectively absorbed, so that the effect of improving image quality by preventing the occurrence of intercolor bleeding increases.

The particle size of the powder used in the powder spraying step of the present invention is preferably 300 μm or less, more preferably 200 μm or less, and 100 μm or less.
More preferably, it is not more than μm. Here, if the particle diameter of the powder exceeds 300 μm, the distribution of the paper powder on the recording medium becomes uneven, and the effect of preventing the occurrence of intercolor bleeding becomes insufficient. It is preferable that the amount of powder applied per unit area of the recording medium is 0.1 to 30 g / m ^2, more preferably from 0.5 to 20 g / m ^2,
More preferably, it is 1 to 15 g / m ² . here,
The amount of powder applied per unit area of the recording medium is 30
If it exceeds g / m ² , the powder may adhere to the printer head, block the nozzles, and cause ejection failure. On the other hand, if the amount of the powder applied per unit area of the recording medium is less than 0.1 g / m ² , the image quality tends to be insufficiently improved by preventing the occurrence of intercolor bleeding. Become.

Further, as the ratio of the material between the powder and the aqueous ink, the value obtained by dividing the mass of the aqueous ink by the mass of the powder (the mass of the aqueous ink / the mass of the powder) is preferably 200 or less. More preferably, 100 or less, more preferably 2 or less.
More preferably, it is 0 or less. Here, when the above value exceeds 200, the ability to separate the coloring material and the solvent by the powder is insufficient, and the tendency that the image quality cannot be sufficiently improved by preventing the occurrence of intercolor bleeding increases. .

In the case where the above-mentioned aqueous ink is used in the present invention, the viscosity of the aqueous ink is 1.5 to 1.5.
It is preferably 4.0 mPa · s, and 1.5 to 3.0 mPa · s.
More preferably, it is 0 mPa · s. If the viscosity of the ink exceeds 4.0 mPa · s, the tendency of the ink to rapidly dry significantly decreases. This is considered to be because if the ink has such a viscosity, the permeability to a recording medium such as paper is significantly reduced. On the other hand, when the viscosity of the ink is less than 1.5 mPa · s, it tends to be difficult to obtain a sufficient optical density. It is considered that this is because the permeability to a recording medium such as paper significantly increases.

Next, the case where an oil-based ink is used in the ink jet recording method of the present invention will be described.

The coloring material contained in the oil-based ink used in the present invention is not particularly limited.
Pigments, dyes and the like can be used. When a pigment is used, either an organic pigment or an inorganic pigment can be used as the pigment, and the pigment used in the above-described aqueous ink can be used. When a dye is used, an oil-soluble dye, a disperse dyestuff, or the like is used as the dye. Specific examples of oil-soluble dyes include CISolvent Yellow-2, -6, -1
4, -15, -16, -19, -21, -33, -56, -61, -80, CISo
lvent Orange-1, -2, -5, -6, -14, -37, -40, -44,-
45, CISolvent Red-1, -3, -8, -23, -24, -25, -2
7, -30, -49, -81, -82, -83, -84, -100, -109, -12
1, CISolvent Blue-2, -11, -12, -25, -35, -36, -5
5, -73, CISolvent Black-3, -5, -7, -22, -23, C.
I.Acid Black-123, CISolvent Violet-8, -3, -14,
-21, -27, CISolvent Green-3, CISolvent Brown-
3, -5, -20, -37 and the like. As disperse dyes,
CIDisperse Yellow-1, -3, -4, -5, -7, -8, -23, -3
1, -33, -39, -42, -49, -50, -51, -54, -56, -60, -6
1, -64, -66, -71, -72, -76, -78, -79, CIDisperse
Orange-1, -3, -5, -11, -13, -20, -21, -30, -32,-
41, -43, -45, -46, -49, -50, -51, CIDisperse Red
-1, -4, -5, -7, -11, -12, -13, -15, -17, -43, -5
2, -53, -54, -55, -56, -58, -59, -60, -65, -72, -7
3, -74, -75, -76, -80, -82, -84, -90, -91, -92,-
94, -97, -98, -99, -103, -104, -113, -116, -117,-
122, -125, -126, -127, -128, -129, CIDisperse Vi
olet-1, -4, -8, -10, -18, -23, -24, -26, -28, -3
0, -33, -37, -38, CIDisperse Blue-3, -5, -6,-
7, -20, -26, -27, -44, -52, -54, -55, -56, -58, -6
0, -61, -62, -64, -72, -75, -79, -81, -85, -87,-
88, -90, -91, -92, -94, -97, -98, -99, -103, -10
4, -105, -106, -108, CISolvent Black-1, -2, -1
0, -26, -27, -28, -29, -30, -31 and the like.

The content of the coloring material contained in the oil-based ink described above is 0.5 to 20 with respect to the total mass of the oil-based ink.
% By mass, and more preferably 1 to 10% by mass. When the content is less than 0.5% by mass, a tendency that a sufficient optical density cannot be obtained increases. On the other hand, if the content exceeds 20% by mass, it tends to be difficult to smoothly eject the ink onto a recording medium such as plain paper.

As the solvent, organic solvents such as aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, ketones, esters, ethers and glycols are used. Specific examples of the aliphatic hydrocarbon include n-hexane, cyclohexane, n-heptane, methylhexane, n-octane,
Examples include methylheptane, dimethylhexane, nonane, and decane. Examples of the aromatic hydrocarbon include toluene, ethylbenzene, xylene, and the like. Examples of alcohols include methanol, ethanol, propanol, butanol, hexanol, benzyl alcohol and the like. Ketones include acetone, methyl ethyl ketone, pentanone, hexanone, heptanone, cyclohexanone and the like. As esters,
Examples include methyl acetate, ethyl acetate, vinyl acetate, ethyl propionate, and ethyl butyrate. Examples of ethers include diethyl ether, ethyl bromo ether, ethyl isopropyl ether and the like. Examples of the glycols include ethylene glycol, diethylene glycol, propanediol, hexanediol, and glycerin. In addition, glycol derivatives such as ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, diethylene glycol ethyl ether, and diethylene glycol butyl ether may be used as the solvent.

Among the above-mentioned solvents, alcohols such as ethanol, propanol, butanol and hexanol;
Further, glycol derivatives such as ethylene glycol ethyl ether, diethylene glycol ethyl ether, and diethylene glycol butyl ether are preferably used. In the present invention, it is preferable to use at least one of the above-mentioned solvents. Further, the content of the solvent contained in the oil-based ink is preferably from 20 to 99% by mass, more preferably from 30 to 99% by mass, and more preferably from 70 to 98% by mass, based on the total mass of the oil-based ink. Is more preferable. When the content of the solvent is less than 20% by mass, it tends to be difficult to smoothly print the oil-based ink on the recording medium. On the other hand, if the content of the solvent exceeds 99% by mass, the optical density of a printed image (recorded matter) tends to be low.

In addition, a polymer compound can be added from the viewpoint of adjusting the viscosity of the oil-based ink or improving the dispersibility of the pigment in the oil-based ink. Examples of the polymer compound include a resin such as a copolymer including a repeating unit based on a monomer having an ethylenically unsaturated group. Specific examples of such a copolymer include ethylene, propylene, butene, pentene, hexene, vinyl acetate, allyl acetate, ethyl crotonate, acrylic acid, maleic acid,
At least one of diethyl maleate, acrylamide, etc.
Copolymers comprising a repeating unit based on a kind of monomer are exemplified.

Further, a compound having an ethylenically unsaturated bond and a photopolymerization initiator can be added to the oil-based ink. When these compounds are combined in the oil-based ink, it is possible to cure the oil-based ink forming the printed matter by irradiating the printed matter with ultraviolet rays or an electron beam. Examples of the compound having an ethylenically unsaturated bond include vinyl acetate, allyl acetate, diallyl phthalate, ethyl crotonate, acrylic acid, maleic acid, diethyl maleate, and acrylamide. Also, as a photopolymerization initiator, by irradiating light,
The compound is not particularly limited as long as it can initiate a polymerization reaction of the compound having an ethylenically unsaturated bond. The type of the polymerization reaction is not particularly limited, and may be any of radical polymerization, cationic polymerization, and anionic polymerization. Specific examples of such a photopolymerization initiator include benzophenone, 2-hydroxy-2
-Methyl-1-phenyl-propan-1-one, 2,2-dimethoxy-1,2-diphenylmethane-1-one, bis (2
4,6-trimethylbenzoyl) -phenylphosphine oxide, η ⁵ -cyclopentadienyl-η ⁶ -cumenyl-
Iron (1 +)-hexafluorophosphate (1−)
And the like.

Further, as the powder when the oil-based ink is used, an oil-absorbing polymer or a water-absorbing polymer can be used. Specific examples of such an oil-absorbing polymer include cellulose acetate, 12-hydroxystearic acid, polyacrylonitrile, polyurethane, polyethylene, vinyl acetate copolymer, polymethyl methacrylate, and polystyrene.

Further, depending on the combination with the solvent in the oil-based ink, a water-absorbing polymer which can be used in the above-described aqueous ink can also be used. In particular, polyacrylonitrile, polyurethane, polyethylene-vinyl acetate copolymer, polymethyl methacrylate, polystyrene, carboxymethylcellulose, methylcellulose, polyacrylic acid, polyacrylamide, polyvinyl alcohol, etc., have a large liquid absorption and prevent the occurrence of color bleeding This is preferable from the viewpoint that the effect of improving the image quality is great. In addition, when a water-absorbing polymer is used, some combinations of the solvent and the powder in the oil-based ink are important because some combinations do not absorb the liquid depending on the solvent of the oil-based ink. Although it cannot be stated unconditionally, when a water-absorbing polymer is used, it is preferable to use a hydrophilic solvent such as alcohols.

When oil-based ink is used, the particle diameter of the powder used in the powder spraying step is 300 μm.
It is preferably at most 200 μm, more preferably at most 100 μm. Here, if the particle diameter of the powder exceeds 300 μm, the distribution of the paper powder on the recording medium becomes uneven, and the effect of preventing the occurrence of intercolor bleeding becomes insufficient. The amount of powder applied per unit area of the recording medium is 0.1 to 30 g /
It is preferably m ^2, and more preferably from 0.5 to 20 g / m ^2, and still more preferably from 1 to 15 g / m ^2. Here, if the amount of the powder applied per unit area of the recording medium exceeds 30 g / m ² , the powder may adhere to the printer head, block the nozzle, and cause ejection failure. On the other hand, if the amount of the powder applied per unit area of the recording medium is less than 0.1 g / m ² , the image quality tends to be insufficiently improved by preventing the occurrence of intercolor bleeding. Become.

Further, as the ratio of the material between the powder and the oil-based ink, the value obtained by dividing the mass of the oil-based ink by the mass of the powder (mass of the oil-based ink / mass of the powder) is preferably 200 or less. More preferably, 100 or less, more preferably 2 or less.
More preferably, it is 0 or less. Here, when the above value exceeds 200, the ability to separate the coloring material and the solvent by the powder becomes insufficient, and the tendency that the image quality cannot be sufficiently improved by preventing the occurrence of intercolor bleeding increases. .

The image forming apparatus which operates based on the ink jet recording method of the present invention and has an arrangement for forming an image is not particularly limited. For example, a general ink jet recording apparatus, a method for controlling ink drying, and the like. It is also possible to use a recording device equipped with a heater or the like, a recording device equipped with an intermediate transfer mechanism, and printing a recording material on the intermediate and then transferring it to a recording medium such as paper.

Hereinafter, preferred embodiments of the image forming apparatus of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts have the same reference characters allotted, and overlapping description will be omitted.

FIG. 1 is a perspective view showing the appearance of a preferred embodiment of the image forming apparatus of the present invention. FIG. 2 shows FIG.
FIG. 2 is a perspective view showing a basic configuration inside the image forming apparatus of FIG.
The image forming apparatus 100 of the present embodiment has a configuration that operates based on the above-described inkjet recording method of the present invention to form an image. That is, as shown in FIGS. 1 and 2, the image forming apparatus 100 mainly includes the external cover 6.
A tray 7 on which a predetermined amount of the recording medium 1 such as plain paper can be placed; a conveying roller (conveying means) 2 for conveying the recording medium 1 into the image forming apparatus 100 one by one; And a powder dispersing device (powder supply means) 3 for dispersing the powder on one surface of the recording medium 1 conveyed along the conveying direction X shown in FIGS. An image forming unit 8 (image forming means) for forming an image by ink by ejecting the image on the surface of the recording medium 1 after the body is scattered.

The transport roller 2 is a pair of rollers rotatably disposed in the image forming apparatus 100. The transport roller 2 sandwiches the recording medium 1 set on the tray 7 and moves a predetermined amount of the recording medium 1 at a predetermined timing. Is transferred to the inside of the apparatus 100 one by one.

The powder dispersing device 3 is rotatably arranged upstream of the image forming section 8 in the conveying direction X of the recording medium 1 and can hold a predetermined amount of the powder inside. A column-shaped powder holding unit, which is connected to both ends of the cylindrical large portion and rotates the column-shaped powder holding unit at a predetermined rotation speed around a central axis of the column-shaped powder holding unit as a rotation axis. And a drive unit (not shown). A slit 32 is formed on a side surface of the large cylindrical portion so that a predetermined amount of powder held inside can be sprayed with the rotation of the cylindrical body. Thus, the powder spraying device 3 rotates at a predetermined timing, and sprays a predetermined amount of powder on the surface of the recording medium 1 being conveyed.

The image forming section 8 forms an image with ink on the surface of the recording medium 1 after the powder conveyed from the powder sprinkling device 3 has been sprayed. The image forming unit 8 mainly includes a recording head 4, an ink set 5, a power supply signal cable 9,
, A carriage 10, a guide rod 11, a timing belt 12, a drive pulley 13, and a maintenance station 14.

The ink set 5 includes ink tanks 52, 54, and 5 in which inks of different colors are stored so as to be ejected.
6, 58. The recording head 4 is provided with nozzles, and a power supply signal cable 9 and an ink set 5 are further connected. Then, when external image recording information is input to the recording head 4 from the power supply signal cable 9, the recording head 4 sucks a predetermined amount of ink from each ink tank based on the image recording information and places the ink on the surface of the recording medium. Discharge. The power supply signal cable 9 also has a role of supplying power necessary for driving the recording head 4 to the recording head 4 in addition to the image recording information.

The recording head 4 is mounted on the carriage 10
The carriage 10 is connected to a guide rod 11 and a timing belt 12 connected to a driving pulley 13. With such a configuration,
The recording head 4 is movable along a guide rod 11 in a direction Y which is parallel to the surface direction of the recording medium 1 on which the powder is scattered and which is perpendicular to the conveying direction X of the recording medium 1. . That is, when the drive pulley 13 is rotated at a predetermined timing based on the image recording information, the carriage 10 on which the recording head 4 is mounted is driven along the guide rod 11 via the timing belt 12, and the recording medium 1 is rotated. An image is formed in a predetermined area on the surface of.

The image forming apparatus 100 is provided with control means (not shown) for adjusting the driving timing of the recording head 4 and the driving timing of the carriage 10 based on the image recording information. Thereby, an image based on the image recording information can be continuously formed in a predetermined area on the surface of the recording medium 1 conveyed at a predetermined speed along the conveyance direction X.

Also, the maintenance station 14
It is connected to a decompression device (not shown) via a tube 15. Further, the maintenance station 14 is connected to the nozzle portion of the recording head 4, and the pressure of the recording head 4 is reduced by reducing the pressure in the nozzle of the recording head 4.
Has a function of sucking ink from the nozzles. By providing the maintenance station 14, extra ink attached to the nozzles is removed as needed while the image forming apparatus 100 is operating, and evaporation of ink from the nozzles is suppressed when the operation is stopped. be able to.

Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments. For example, the image forming apparatus 1 of the above embodiment
In the case of 00, the case where the powder dispersing device (powder supply means) 3 is composed of a cylindrical powder holding unit having the slit 32 formed thereon and a driving unit for rotating the same is described. In the image forming apparatus, the shape of the powder holding unit of the powder spraying device (powder supply means) and the type of powder spraying are not particularly limited. For example, as in a powder dispersing device 3a shown in FIGS. 3A and 3B, a rectangular parallelepiped shape in which a lower surface facing the surface of the recording medium 1 is a mesh for dispersing powder is used. It may be a powder holding unit. In this case, the powder may be sprayed by vibrating the powder holding unit. As shown in FIG. 4, an electrostatic field is formed between the powder spraying device 3a and the recording medium 1. The charging may be performed by providing a charging unit 36 that performs the charging.
In the case of the powder spraying type in which the powder holding unit is vibrated, the urging of urethane or the like is performed between the vibrating powder holding unit of the powder spraying device 3a and the surface of the recording medium 1 as shown in FIG. The rotatable roll-shaped soft body 37 may be arranged to improve the dispersion state of the powder sprayed on the surface of the recording medium 1.

The powder spraying device (powder supply means)
As shown in the powder spraying device 3b shown in FIGS. 6 (a) and 6 (b), the recording medium 1
It is also possible to provide a supply and discharge opening 33 for supplying the recording medium 1 to be conveyed through the inside of the powder holding unit and to spray the powder P on its surface. Furthermore,
In this case, a configuration such as the powder dispersing device 3c shown in FIGS. 7A and 7B may be adopted. That is, the size of the powder holding unit is set to a size capable of storing the recording medium 1 one by one, a shutter 35 is provided in each of the openings 33, and a porous member in which the powder P is placed inside the powder holding unit. It is also possible to provide a gas permeable plate 38 formed of a porous material, and further, to blow air A from the back of the gas permeable plate to float the powder inside the powder holding unit.

Further, the image forming apparatus 10 of the above embodiment
At 0, the powder dispersing device (powder supply means) 3 is disposed on the upstream side of the image forming unit (image forming means) 8 with respect to the conveying direction X of the recording medium 1 of the conveying roll (conveying means) 2. Although the image forming unit 8 forms an image using ink on the surface of the recording medium 1 after the powder has been sprayed by the powder spraying device 3, the image forming apparatus according to the present invention has the above-described configuration. The present invention is not limited to the embodiment. For example, a powder capable of separating a coloring material and a solvent in the ink toward the surface of the recording medium after the image is formed by the image forming unit using the ink Powder supply means for spraying
Controls the time from the start or end of ejection of the ink in the image forming means to the start of spraying of the powder in the powder supply means based on the landing conditions of the ink on the recording medium and the permeability of the ink into the recording medium. And a control unit that performs the control. The conditions for landing the ink on the recording medium can be determined by the interval between the print head and the recording medium, the ejection speed of the ink drop, the degree of conveyance of the recording medium, and the like. The permeability of the ink into the recording medium can be determined by the ink composition, the amount of ink per unit area of the recording medium, the type of recording butterfly, and the like.

As described above, the powder supply means for spraying the above-mentioned powder after the ink has landed on the recording medium, the conditions for the ink to land on the recording medium, and the penetrability of the ink into the recording medium. If control means for controlling the time from the start or end of the ejection of ink in the image forming means to the start of spraying of the powder in the powder supply means is provided, the operation according to the above-described inkjet recording method of the present invention can be performed. Feathering, intercolor bleeding,
It is possible to sufficiently prevent problems such as curling and cuckling. Therefore, this image forming apparatus can also obtain a printed image having excellent image quality.

[0083]

EXAMPLES Hereinafter, the ink jet recording method and the image forming apparatus of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

By combining any of the following pigment dispersion methods 1 and 2 with the ink preparation method, inks A to D
Was prepared. In the following description, the number of EOs is
The substance amount (mol) of the ethylene oxide group is shown.

[Pigment Dispersion Method 1] A pigment that is self-dispersible in commercially available water was dispersed in ion-exchanged water as follows to obtain a pigment dispersion. That is, a mixture of a pigment self-dispersible in water and ion-exchanged water is subjected to a centrifugal separation treatment (8000 rpm × 30 minutes) using a centrifugal separator, and a residue portion (20 vol.% With respect to the total volume). The pigment was removed to obtain a pigment dispersion.

[Pigment dispersion method 2] First, 10% by mass of a pigment and 2.5% by mass of a polymer dispersant were added to ion-exchanged water, and the pigment was dispersed using an ultrasonic homogenizer. Was. Next, this dispersion was subjected to a centrifugal separation treatment (8000 rpm × 30 minutes) using a centrifugal separator to remove a residue portion (20 vol.% With respect to the total volume) to obtain a pigment dispersion. .

[Method of Preparing Ink-Jet Ink] A predetermined amount of a dispersion prepared by either the pigment dispersion method 1 or the pigment dispersion method 2 or a commercially available coloring material concentrated liquid is used, and a solvent and other additives are added thereto. A predetermined amount was added, mixed, stirred, and passed through a 1 μm filter to prepare an inkjet ink having a total amount of 100 parts by weight and a color material concentration adjusted to a predetermined concentration.

[Ink A] An inkjet ink having the following composition (total amount: 100 parts by weight) was obtained by the pigment dispersion method 1 and the inkjet ink preparation method.

That is, the composition is Cabojet 300 which is a pigment.
(Cabot): 3 parts by weight, water-soluble organic solvent thiodiethanol: 10 parts by weight, water-soluble organic solvent diethylene glycol: 10 parts by weight, surfactant Surfynol 465 (EO number = 10, day Shin Chemical Co.): 0.6 parts by weight, urea: 6 parts by weight, ion-exchanged water: balance. Physical properties of this inkjet ink were: viscosity: 2.2 mPa · s.

[Ink B] An inkjet ink having the following composition (total amount: 100 parts by weight) was obtained by the pigment dispersion method 2 and the inkjet ink preparation method.

That is, the composition of the pigment is Black Pear
ls L (Cabot): 4 parts by weight, styrene-methacrylic acid copolymer as a polymer dispersant (weight average molecular weight;
About 6200): 0.8 parts by weight, water-soluble organic solvent diglycerin ethylene oxide adduct: 5 parts by weight, water-soluble organic solvent diethylene glycol: 15 parts by weight, surfactant polyoxyethylene 2-ethylhexyl ether ( EO number = 30): 0.03 parts by weight, ion-exchanged water: balance,
And The physical properties of this ink-jet ink are viscosity;
It was 2.6 mPa · s.

[Ink C] An ink-jet ink (total amount: 100 parts by weight) having the following composition was obtained by the pigment dispersion method 2 and the ink-jet ink preparation method.

That is, the composition of the pigment is CI Pigmen
t Blue 15: 3: 3 parts by weight, styrene-methacrylic acid copolymer as a polymer dispersant (weight average molecular weight: about 620
0): 1 part by weight, water-soluble organic solvent sulfolane: 10 parts by weight, water-soluble organic solvent diethylene glycol: 5
Parts by weight, propylene glycol which is a water-soluble organic solvent:
5 parts by weight, polyoxyethylene 2-ethylhexyl ether (EO number = 9): 0.5 part by weight, urea: 6 parts by weight, ion-exchanged water: balance. Physical properties of this inkjet ink were: viscosity; 2.4 mPa · s.

[Ink D] An inkjet ink having the following composition (total amount: 100 parts by weight) was obtained by the inkjet ink preparation method.

That is, the composition is a dye CIDirect
Blue 199: 2 parts by weight, CIAcid Blue 9: 1 part by weight, water-soluble organic solvent thiodiethanol: 10 parts by weight, water-soluble organic solvent diethylene glycol: 5 parts by weight, water-soluble organic solvent propylene glycol: 5 Parts by weight,
Diethylene glycol as a water-soluble organic solvent: 10 parts by weight, N, N'-bis (2-hydroxyethyl) -2-aminoethanesulfonic acid: 1.2 parts by weight, sodium hydroxide: 0.6 parts by weight, Surfactant as a surfactant Nol 465 (EO number = 10, manufactured by Nisshin Chemical Co., Ltd.): 0.5 part by weight, urea: 6 parts by weight, ion-exchanged water: remaining part. Physical properties of this inkjet ink were: viscosity: 2.0 mPa · s.

[Ink E] An inkjet ink having the following composition (total amount: 100 parts by weight) was obtained by the inkjet ink preparation method.

That is, the composition is a dye CISolven
t Yellow-2: 2.5 parts by weight, isopropyl alcohol as a solvent: 60 parts by weight, diethylene glycol monobutyl ether as a solvent: 35 parts by weight, and polyacrylic acid as another additive: 2.5 parts by weight. The viscosity of this ink was 4.5 mPa · s.

[Ink F] An ink-jet ink having the following composition (total amount: 100 parts by weight) was obtained by the ink-jet ink preparation method.

That is, the composition is a dye CISolven
t Blue-2: 2.5 parts by weight, isopropyl alcohol as a solvent: 60 parts by weight, diethylene glycol monobutyl ether as a solvent: 35 parts by weight, and polyacrylic acid as another additive: 2.5 parts by weight. The viscosity of this ink was 4.5 mPa · s.

(Example 1) FIG. 3 shows a configuration in which the mesh portion is opened only when the recording medium has passed and the powder is sprayed.
FIGS. 1 and 2 except that a powder dispersing device similar to the powder dispersing device 3a shown in FIGS.
The image forming apparatus having the same configuration as the image forming apparatus 100 shown in FIG. 1 is used, and ink A, ink C and polyacrylic acid (powder, average particle size: 80 μm) are set in this apparatus, and the 100% coverage pattern is set. And the line pattern were printed. Note that the image forming apparatus has a resolution of 800 dpi and 16 dpi.
A zero-nozzle thermal inkjet printhead was used. In addition, L paper (manufactured by Fuji Xerox Office Supply Co., Ltd.) was used as a recording medium. And the printing and evaluation of this inkjet ink, the temperature 23 ± 0.5 ℃,
Humidity 55 ± 5% R. H was performed under the conditions of H. Further, the spray amount of polyacrylic acid was 1.5 g / m ² .

(Example 2) 100% in the same manner as in Example 1 except that ink A, ink D and carboxymethylcellulose (powder, average particle diameter: 60 µm) were set in the same image forming apparatus as in Example 1. The coverage pattern and line pattern were printed. The amount of carboxymethylcellulose (hereinafter referred to as CMC) was 3 g / m ² .

(Embodiment 3) In the same image forming apparatus as in Embodiment 1, ink B, ink C and magnesium nitrate (powder,
A 100% coverage pattern and a line pattern were printed in the same manner as in Example 1 except that the average particle size was set to 120 μm. In addition, magnesium nitrate (hereinafter, MgN
O ₃ ) was 2 g / m ² .

Example 4 An ink-forming apparatus similar to that of Example 1 was set with ink E, ink F and polyethylene-vinyl acetate copolymer (powder, average particle diameter: 110 μm), and a 100% coverage pattern and line were set. The pattern was printed. Note that an 800 dpi, 160 nozzle piezo inkjet type prototype print head was used for the image forming apparatus. The spraying amount of the polyethylene-vinyl acetate copolymer was 5 g / m ² .

Comparative Example 1 Example 1 was repeated except that ink B and ink C were set in the same image forming apparatus as in example 1.
A 100% coverage pattern and a line pattern were printed in the same manner as described above.

Comparative Example 2 A 100% coverage pattern and a line pattern were obtained in the same manner as in Example 1 except that the ink B, the ink C, and the 10% by mass aqueous solution of carboxymethyl cellulose were set in the same image forming apparatus as in Example 1. Printed. The application of a 10% by mass aqueous solution of carboxymethylcellulose to plain paper was performed using a prototype inkjet device. And the spraying amount of the carboxymethylcellulose 10% by mass aqueous solution was 7.5 g / m ² .

[Evaluation of Inkjet Recording Method] Images printed on plain paper by the methods of Examples 1 to 3 and Comparative Examples 1 and 2 were allowed to stand for 24 hours, and the degree and color of print bleeding (feathering) were observed. The degree of inter-bleeding and the degree of curling were evaluated under the following evaluation criteria.

In the evaluation of the bleeding of the prints printed using the above-mentioned respective ink jet recording methods, the degree of the bleeding of the line pattern was checked against a predetermined limit sample, and the sensory evaluation was performed. And about the obtained degree of bleeding,
;: Less bleeding, △: slightly bleeding but within allowable range, ×: severely bleeding out of allowable range,
Each ink jet recording method was evaluated based on the evaluation criteria described above. Table 1 shows the results.

The evaluation of the intercolor bleeding of the prints printed using each of the above-described ink jet recording methods is performed by printing inks of different colors adjacent to each other, and determining the degree of bleeding of the adjacent portions in advance. And sensory evaluation was performed.
In this case, ；: no occurrence of intercolor bleeding was observed, Δ: slight occurrence of intercolor bleeding was observed but within the allowable range, x: one in which the occurrence of intercolor bleeding was severe and out of the allowable range The respective ink jet recording methods were evaluated based on the evaluation criteria described above. Table 1 shows the results.

Further, the evaluation of the degree of curl generated on plain paper after printing using each of the above-described ink jet recording methods was evaluated by printing a 100% coverage pattern and allowing the paper to stand for one day under a general environment. The measurement was performed by measuring the curl height (warpage height) of the end of the paper after the standing. Then, regarding the degree of curl obtained, ○: curl height is 20 m
m or less; ×; each inkjet ink was evaluated based on the evaluation criteria that the curl height exceeded 20 mm. Table 1 shows the results.

[0110]

[Table 1]

[0111]

As described above, according to the present invention, by spraying a predetermined amount of powder capable of separating the coloring material and the solvent in the ink on the surface of the recording medium,
Provided are an ink jet recording method and an image forming apparatus which can sufficiently prevent problems such as feathering, color bleeding, curl and cuckle, and can obtain excellent image quality regardless of the type of recording medium. be able to.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an external configuration of an image forming apparatus according to the present invention.

FIG. 2 is a perspective view showing an internal configuration of the image forming apparatus shown in FIG.

FIG. 3A is a perspective view showing another embodiment of the powder dispersion device 3 mounted on the image forming apparatus shown in FIG. 1,
(B) is a front view of the mesh part which sprays the powder of the powder spraying apparatus shown in (a).

FIG. 4 is a perspective view showing another embodiment of the powder spraying device shown in FIG.

FIG. 5 is a perspective view showing still another embodiment of the powder dusting apparatus shown in FIG. 3;

FIG. 6A is a perspective view showing still another embodiment of the powder spraying device 3 mounted on the image forming apparatus shown in FIG. 1, and FIG. 6B is a powder spraying device shown in FIG. FIG.

7A is a perspective view showing still another embodiment of the powder dusting apparatus shown in FIG. 6, and FIG. 7B is a sectional view of the powder dusting apparatus shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording medium, 2 ... Conveying roller, 3, 3a, 3b, 3c
... powder sprayer, 4 ... recording head, 5 ... ink set,
6 external cover, 7 tray, 8 image forming unit, 9 power supply signal cable, 10 carriage, 11 guide rod, 12 timing belt, 13 drive pulley, 14
... Maintenance station, 15 ... Tube, 32 ...
Slit, 33 opening, 35 shutter, 36 charging means, 37 soft body, 38 plate, 52 ink tank, 100 image forming apparatus, A air, P powder, X
Transport direction.

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2C056 EA05 FC01 FC02 HA41 2H086 BA02 BA52 BA53 BA55 4J039 BA04 BC05 BC07 BC09 BC13 BC19 BC29 BC33 BC35 BC50 BC54 BC55 BE01 BE03 BE04 BE06 BE07 BE08 BE12 CA06 CA07 EA15 EA16 EA17 EA19 EA19 GA24

Claims (9)

[Claims] 1. An ink jet recording method for ejecting an ink having a coloring material and a solvent toward a surface of a recording medium and forming an image with the ink on the surface of the recording medium, the method comprising: An ink jet recording method, comprising a powder spraying step of spraying powder capable of separating a coloring material and the solvent toward a surface of the recording medium. 2. The ink jet recording method according to claim 1, wherein, after the powder is sprayed on the surface of the recording medium in the powder spraying step, the ink is ejected on the surface of the recording medium. Recording method. 3. The ink according to claim 1, wherein the colorant is a water-soluble organic solvent as the colorant, and a water-soluble organic solvent as the solvent.
3. An aqueous ink containing water, and the powder is at least one selected from the group consisting of a water-absorbing polymer and an electrolyte capable of coagulating the pigment. 3. The inkjet recording method according to item 1. 4. The ink jet recording method according to claim 3, wherein the electrolyte is any one selected from the group consisting of a polyvalent metal salt and a cationic electrolyte. 5. The method according to claim 1, wherein the ink is an oil-based ink containing a coloring material and a solvent, and the powder is at least one selected from the group consisting of an oil-absorbing polymer and a water-absorbing polymer. The ink jet recording method according to claim 1 or 2, wherein: 6. A conveyance unit for conveying the recording medium, and an ink containing a color material and a solvent is ejected toward a surface of the recording medium conveyed by the conveyance unit, and the ink is discharged onto the surface of the recording medium. An image forming apparatus comprising: an image forming unit that forms an image using ink, wherein the recording medium is configured to convey a powder capable of separating the coloring material and the solvent in the ink by the conveying unit. Powder supply means for spraying toward the surface, the powder supply means is disposed on the upstream side of the image forming means with respect to the conveying direction of the recording medium of the conveying means, and, The image forming apparatus according to claim 1, wherein the image forming unit forms an image using the ink on a surface of the recording medium after the powder is sprayed by the powder supply unit. 7. The ink according to claim 1, wherein the colorant is a self-dispersible pigment in water, and the solvent is a water-soluble organic solvent.
7. An aqueous ink containing water, and wherein the powder is at least one selected from the group consisting of a water-absorbing polymer and an electrolyte capable of aggregating the pigment. Image forming apparatus. 8. The image forming apparatus according to claim 7, wherein the electrolyte is any one selected from the group consisting of a polyvalent metal salt and a cationic electrolyte. 9. The method according to claim 1, wherein the ink is an oil-based ink containing a coloring material and a solvent, and the powder is at least one selected from the group consisting of an oil-absorbing polymer and a water-absorbing polymer. The image forming apparatus according to claim 6.