JPH11349873A - Recording material and image formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording material which exhibits a high optical density and is excellent not only in image fixation properties but also in long-term storage stability and jetting characteristics stability and to provide an image formation method using the same. SOLUTION: In a recording material comprising a colorless or light-colored soln. contg. an electrolyte, a water-soluble org. solvent, and water and an ink contg. a pigment self-dispersible in water, an anionic compd., a water-soluble org. solvent, a surfactant, and water, the number of particles having particle sizes of 0.5 μm or higher is made to be 1×10<11> /l or higher and the number of particles having particle sizes of 5 μm or higher is made to be 1×10<9> /l or higher. This material is used in recording by an ink jet recording method to form images.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material,
The present invention relates to a recording material including a colorless or pale solution and an ink containing a pigment, and an image forming method using the recording material.

[0002]

2. Description of the Related Art Liquid or molten solid ink is ejected from nozzles, slits or porous films, etc.
2. Description of the Related Art A so-called ink jet printer that performs recording on a cloth, a film, or the like has various advantages such as small size, low cost, quietness, and the like, and is widely sold as a black single-color or full-color printer. Above all, the so-called piezo ink-jet method using a piezoelectric element and the so-called thermal ink-jet method in which droplets are formed by applying thermal energy to perform recording have many advantages such as high-speed printing and high resolution. doing.

Heretofore, inks using water-soluble dyes generally used in ink jet recording systems have excellent long-term storage stability, but have problems in water resistance and light resistance. On the other hand, inks using pigments are very promising because they are excellent in water resistance and light resistance and can obtain image quality without bleeding at a high density, and in recent years many proposals have been made and put to practical use. I have.

For example, JP-A-56-147871 proposes a recording liquid comprising an aqueous medium containing a pigment, a polymer dispersant, and a nonionic surfactant. Also, U.S. Pat. Nos. 5,085,698 and 5,221.
No. 334 proposes to use AB or BAB block copolymers as pigment dispersants. Further, U.S. Pat. No. 5,172,133 proposes to use certain pigments, water-soluble resins and solvents. However, in the case of an ink in which a pigment is dispersed using a dispersant, when a large amount of a surfactant is added to the ink, there is a problem that the dispersion stability of the pigment is reduced and the long-term storage stability is poor.

On the other hand, as a method of dispersing a pigment without using a dispersant, US Pat. No. 5,571,311 discloses a method of introducing a substituent containing a water-solubilizing group into carbon black. Japanese Patent Application Laid-Open No. Hei 8-81646 discloses a method of causing carbon black to be oxidized, and Japanese Patent Application Laid-Open No. 8-3498 discloses a method of oxidizing carbon black.

It is known that an ink using a pigment generally has a problem in image fixability. A method of increasing the image fixing property by adding a surfactant to the ink is disclosed in JP-A-55-65269, etc., but when this method is applied to an ink using a pigment, the image fixing property is increased. However, there is a problem that sufficient image density cannot be obtained.

On the other hand, a method of insolubilizing a dye or the like by acting a liquid containing a polyvalent metal salt is disclosed in Japanese Patent Application Laid-Open No. H5-25-2
As described in Japanese Patent No. 02328, etc., when this method is applied to an ink using a pigment, a problem occurs in that the image fixing property is deteriorated although the image density is increased.

Japanese Patent Application Laid-Open No. 8-193175 discloses a method of combining a liquid composition containing a cationic substance and a nonionic polymer substance with an ink containing an anionic compound. This is a method in which the coloring material is aggregated by a cationic substance, and the generated aggregate is adsorbed to a nonionic polymer substance, thereby fixing the coloring material in a recording medium, and achieving both image fixing property and optical density. is there. Further, a method similar to this method is disclosed in JP-A-8-1978.
No. 40, JP-A-9-286940 and the like.

However, it is impossible to obtain a recording material having high optical density, excellent image fixability, and excellent long-term storage stability and ejection characteristic stability by any of these methods. Was.

[0010]

Accordingly, the present invention has a high optical density when a pigment ink is used,
It is an object of the present invention to provide a recording material which is excellent in image fixing property and also has excellent long-term storage stability and ejection characteristic stability, and an image forming method using the recording material.

[0011]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a colorless or pale-colored solution containing a certain component,
It has been found that the above-mentioned object can be achieved by setting the relationship between the particle size and the number of particles contained in the recording material in a recording material obtained by combining an ink containing a certain component with the ink in a certain range. Completed the invention.

That is, the present invention provides a colorless or pale solution containing an electrolyte, a water-soluble organic solvent and water, a water-dispersible pigment, an anionic compound, a water-soluble organic solvent, a surfactant and water. In a recording material composed of an ink and a contained ink, the number of particles of 0.5 μm or more present in 1 liter of the recording material is 1 × 10 ¹¹ or more, and the number of particles of 5 μm or more is 1 × 10 ⁹ or more. And an image forming method using the recording material.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The recording material of the present invention comprises a colorless or pale solution and ink. The colorless or pale solution and the ink will be described in detail below. [A] Colorless or pale solution First, the "colorless or pale solution" constituting the recording material of the present invention will be described. In the present invention, the “colorless or light-colored solution” refers to a solution having an average absorbance within a range of 400 to 750 nm of 2 or less in absorbance measured using a spectrophotometer. The spectrophotometer is a U-3210 type self-recording spectrophotometer (Hitachi, Ltd.)
Was used for the measurement.

(Components of Colorless or Light-Colored Solution) The colorless or light-colored solution in the recording material of the present invention contains an electrolyte, a water-soluble organic solvent and water as essential components. , A property controlling agent, various additives, and the like. Hereinafter, each component will be described.

1. Electrolyte The electrolyte used in the colorless or pale solution in the present invention includes lithium ion, sodium ion,
Alkali metal ions such as potassium ions, aluminum ions, barium ions, calcium ions, copper ions, iron ions, magnesium ions, manganese ions,
Polyvalent metal ions such as nickel ions, tin ions, titanium ions, zinc ions, and hydrochloric acid, hydrobromic acid, hydroiodic acid,
Sulfuric acid, nitric acid, phosphoric acid, thiocyanic acid, and salts of organic carboxylic acids and organic sulfonic acids such as acetic acid, oxalic acid, lactic acid, fumaric acid, citric acid, salicylic acid, and benzoic acid. In addition, it is also possible to use a cationic substance or the like that becomes an organic cation by dissociation in water,
Specific examples include primary, secondary, tertiary and quaternary amines and salts thereof.

In the present invention, specific examples of the salt that can be used as the electrolyte include lithium chloride, sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, and sodium sulfate. Salts of alkali metals such as potassium nitrate, sodium acetate, potassium oxalate, sodium citrate, potassium benzoate, 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 thionate, calcium chloride, calcium bromide, calcium iodide, Calcium nitrate, calcium nitrate, calcium dihydrogen phosphate, calcium thiocyanate, calcium benzoate, calcium acetate, calcium salicylate, calcium tartrate, 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, iron lactate, 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, nickel acetate, tin sulfate, Titanium chloride, zinc chloride,
Examples include salts of polyvalent metals such as zinc bromide, zinc sulfate, zinc nitrate, zinc thiocyanate, and zinc acetate.

In the present invention, specific examples of the cationic substance that can be used as an electrolyte include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, Polyamines and the like, for example, isopropylamine, isobutylamine, t-butylamine, 2-ethylhexylamine, nonylamine, dipropylamine, diethylamine, trimethylamine, triethylamine, dimethylpropylamine, ethylenediamine, propylenediamine, hexamethylenediamine,
Diethylenetriamine, tetraethylenepentamine, diethanolamine, diethylethanolamine, triethanolamine, tetramethylammonium chloride, tetraethylammonium bromide, dihydroxyethylstearylamine, 2-heptadecenyl-hydroxyethylimidazoline, lauryldimethylbenzylammonium chloride, cetylpyridinium chloride, Aramid methyl pyridium chloride, diallyl dimethyl ammonium chloride polymer, diallylamine polymer, monoallylamine polymer and the like can be mentioned.

Among these electrolytes, preferred are aluminum sulfate, calcium chloride, calcium nitrate, calcium acetate, magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium acetate, tin sulfate, zinc chloride, zinc nitrate, zinc sulfate, Examples include zinc acetate, aluminum nitrate, monoallylamine polymer, diallylamine polymer, diallyldimethylammonium chloride polymer and the like.

The electrolyte may be used alone or as a mixture of two or more. The content of the electrolyte in the colorless or pale solution is 0.1 to 15% by weight, especially 0.5 to 10% by weight.
It is preferable to set the weight%. The electrolyte content is 0.1
When the amount is less than% by weight, the optical density may decrease.
If it exceeds 15% by weight, sufficient image fixing properties may not be obtained.

2. Water-Soluble Organic Solvent The water-soluble organic solvent used in the colorless or pale solution in the present invention includes ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexane. Polyhydric alcohols such as triol and glycerin, 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, etc. A polyhydric alcohol derivative, pyrrolidone, N-methyl-2-pyrrolidone,
Nitrogen-containing solvents such as cyclohexylpyrrolidone and triethanolamine; alcohols such as ethanol, isopropyl alcohol, butyl alcohol, and benzyl alcohol; sulfur-containing solvents such as thiodiethanol, thiodiglycerol, sulfolane, and dimethyl sulfoxide; propylene carbonate; and ethylene carbonate Is mentioned.

The water-soluble organic solvent used for the colorless or pale solution and the ink may be used alone or in combination of two or more. Further, it is preferable to select a more suitable water-soluble organic solvent for use in the ink in consideration of a combination with a pigment, an anionic compound and the like.

The content of the water-soluble organic solvent in the colorless or pale solution is preferably 1 to 60% by weight, particularly preferably 5 to 40% by weight. When the content is less than 1% by weight,
Long-term storage may be poor. On the other hand, when the content exceeds 60% by weight, the ejection stability may be reduced, and the ejection may not be performed normally.

3. Water As the water contained in the colorless or pale solution in the recording material of the present invention, ion-exchanged water, distilled water, pure water, ultrapure water and the like can be used. The content of water in the colorless or pale solution of the invention is from 25 to 99% by weight, especially from 50 to 99% by weight.
Preferably it is 94% by weight. When the content is less than 25% by weight, the ejection stability may be reduced, and the ejection may not be performed normally. If it exceeds 99% by weight, long-term storage stability may be poor.

4. Other Components 1) Carboxylic Acid or Salt of Carboxylic Acid The colorless or pale-colored solvent in the recording material of the present invention may contain a carboxylic acid or a salt of carboxylic acid.
Specific examples of carboxylic acid salts include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, lactic acid, tartaric acid, benzoic acid,
Acrylic acid, crotonic acid, butenoic acid, methacrylic acid, tiglic acid, allylic acid, 2-ethyl-2-butenoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, fumaric acid, methylmaleic acid, glyceric acid , Styrene-
Copolymers of a monomer having an ethylenically unsaturated group such as an acrylic acid copolymer and an unsaturated carboxylic acid, and derivatives of the above carboxylic acids, their alkali metal salts, alkaline earth metal salts, ammonium salts and the like. Can be Among them, acetic acid, salicylic acid, lactic acid, benzoic acid, acrylic acid, methacrylic acid, derivatives thereof, and salts thereof are preferable.

When the colorless or pale solution of the present invention contains a carboxylic acid or a salt of a carboxylic acid, the long-term storage stability and the ejection characteristic stability of the ink jet head can be improved. This is considered to be due to the effect of the inorganic solution absorbing carbon dioxide in the air over time and suppressing the polyvalent metal ion from forming a water-insoluble salt. In particular, when a thermal ink jet system is used, it is known that polyvalent metal ions deteriorate the heater section over time, and it is considered that this has an effect of suppressing the deterioration of the heater section. The content of such a carboxylic acid or a salt of the carboxylic acid in a colorless or pale solution is preferably 10% by weight or less. In particular, the range of 0.1 to 10% by weight is preferable.

2) Property control agent A colorless or pale-colored solution is used for controlling various properties.
Cellulose derivatives such as polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, ethylcellulose, carboxymethylcellulose, polysaccharides and derivatives thereof, other water-soluble polymers, polymer emulsions such as acrylic polymer emulsions, polyurethane emulsions, cyclodextrins, macrocycles Amines, dendrimers, crown ethers, urea and its derivatives, acetamide and the like can be used.
Also, to adjust conductivity and pH, potassium hydroxide,
Sodium hydroxide, compounds of alkali metals such as lithium hydroxide, ammonium hydroxide, triethanolamine, diethanolamine, ethanolamine, nitrogen-containing compounds such as 2-amino-2-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.

The content of these property controlling agents in a colorless or pale solution is preferably 0.1 to 20% by weight.

3) Other additives Further, if necessary, the colorless or pale-colored solution may contain a pH buffer, an antioxidant, a fungicide, a viscosity modifier, a conductive agent, an ultraviolet absorber, a chelating agent, and a water-soluble solution. A coloring dye, a disperse dye, an oil-soluble dye, a surfactant and the like can be added. The content of these additives in a colorless or pale solution is 20
% By weight or less.

(Method for Producing Colorless or Light-Colored Solution) A colorless or light-colored solution can be obtained, for example, by mixing and dissolving the above-mentioned components and filtering through a 0.45 μm filter.

(Electrical Conductivity of Colorless or Light Color Solution) The electric conductivity of the colorless or light color solution is preferably 0.5 to 3.0 S / m, and more preferably 0.8 to 2.0 S / m. More preferred. If the conductivity is higher than 3.0 S / m, it is not possible to obtain sufficient image fixability and sufficient stability of ejection characteristics. It is considered that the cause of the poor image fixing property is that the pigment is hardly penetrated into the recording medium by accelerating the aggregation of the pigment. In addition, the reason why the stability of the ejection characteristics is inferior is that, particularly when printing is performed with a print head of a thermal inkjet method, deterioration of the heater peripheral portion is promoted because a minute current leak is likely to occur in the heater peripheral portion. Can be considered. On the other hand, if the conductivity is smaller than 0.5 S / m, it is not possible to obtain a sufficient optical density. It is considered that this is because the pigment or the pigment aggregate permeates the recording medium due to insufficient aggregation of the pigment.

[B] Ink Next, the “ink” constituting the recording material of the present invention will be described. (Ink component) The ink in the recording material of the present invention is:
It contains a self-dispersible pigment in water, an anionic compound, a water-soluble organic solvent, a surfactant and water as essential components, but can also contain other properties controlling agents, various additives and the like. . Hereinafter, each component will be described.

1. Pigment The pigment used in the ink of the present invention is self-dispersible in water. The pigment that is self-dispersible in water is a pigment that has many water-solubilizing groups on the surface of the pigment and is stably dispersed without the presence of a pigment dispersant. Specifically, by subjecting a so-called pigment to a surface modification treatment such as an acid / base treatment, a coupling agent treatment, a polymer graft treatment, a plasma treatment, or an oxidation / reduction treatment, the pigment can be self-dispersed in water. Pigments can be obtained.

The criterion for determining whether or not water can be self-dispersed is as follows.
Using a dispersing device such as an ultrasonic homogenizer, a nanomizer, a microfluidizer, a ball mill, etc., disperse without using a dispersant as a concentration of water 95 wt% / pigment 5 wt%, measure the initial pigment concentration, and place the dispersion in a glass bottle. When the pigment concentration of the supernatant is measured after being left for 1 day at, it is required that the value be 98% or more of the initial concentration.

The pigment to be surface-modified may be an organic pigment or an inorganic pigment. As the color of the pigment,
In addition to the black, cyan, magenta, and yellow primary color pigments, specific color pigments such as red, green, blue, brown, and white, metallic luster pigments such as gold and silver, colorless or pale extenders, and plastic pigments Can be used. Also,
For the present invention, newly synthesized pigments can also be used.

Examples of the black pigment include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. Specific examples include Raven 7000 and Raven 57
50, Raven5250, Raven5000 UL
TRAII, Raven3500, Raven2000,
Raven 1500, Raven 1250, Raven
1200, Raven 1190 ULTRAII, Rav
en1170, Raven1255, Raven108
0, Raven 1060 (all manufactured by Columbian Carbon Co., Ltd.), Regal400R, Regal330R,
Regal660R, Mogul L, Black Pe
arlsL, Monarch700, Monarch80
0, Monarch 880, Monarch 900, M
onarch1000, Monarch1100, Mo
narch1300, Monarch1400 (or more
Cabot Corporation), Color Black FW1, C
color Black FW2, Color Black
FW2V, Color Black 18, Color
Black FW200, Color Black S1
50, Color Black S160, Color
Black S170, Pritex35, Print
xU, Printex Vintex 140U, Pri
tex 140V, Special Black 6, S
special Black 5, Special Bla
No. 25, No. 33, No. 40, No. ck 4A, Special Black 4 (above, manufactured by Degussa)
47, No. 52, No. 900, No. 2300, MC
F-88, MA600, MA7, MA8, MA100
(Above, manufactured by Mitsubishi Chemical Corporation) and the like, but are not limited thereto.

Examples of cyan pigments include CI Pi
gment Blue-1, CI Pigment Bl
ue-2, CI Pigment Blue-3, C.I.
I. Pigment Blue-15, C.I.Pigme
nt Blue-15: 1, CI Pigment Bl
ue-15: 3, CI Pigment Blue-1
5:34, CI Pigment Blue-16, C.I.
I. Pigment Blue-22, C.I.Pigme
nt Blue-60 and the like, but are not limited thereto.

Examples of magenta pigments include CIP
i.g. Red 5, CI Pigment Re
d 7, C.I.Pigment Red 12, C.I.P
pigment Red 48, CI Pigment R
ed48: 1, CI Pigment Red 57,
CI Pigment Red 112, CI Pigm
ent Red 122, CI Pigment Red
123, C.I.Pigment Red 146, C.I.
Pigment Red 168, CI Pigment
Red 184, CI Pigment Red 202
And the like, but are not limited thereto.

Examples of yellow pigments include CI Pigm.
ent Yellow-1, CI Pigment Ye
llow-2, C.I.Pigment Yellow-
3, CI Pigment Yellow-12, C.I.
I. Pigment Yellow-13, C.I. Pig
ment Yellow-14, C.I.Pigment
Yellow-16, C.I.Pigment Yellow
ow-17, C.I.Pigment Yellow-7
3, CI Pigment Yellow-74, C.I.
I. Pigment Yellow-75, C.I.Pig
ment Yellow-83, C.I.Pigment
Yellow-93, C.I.Pigment Yellow
w-95, C.I.Pigment Yellow-9
7, CI Pigment Yellow-98, C.I.
I. Pigment Yellow-114, C.I.Pi
gment Yellow-128, CI Pigme
nt Yellow-129, CI Pigment Y
yellow-151, CI Pigment Yellow
w-154 and the like, but are not limited thereto.

In addition to the surface-modified pigments described above, Cab-o-jet-200, C
ab-o-jet-300 and IJX-55, Microjet Black CW- manufactured by Orient Chemical Co., Ltd.
1. A commercially available water-dispersible pigment, such as a pigment sold by Nippon Shokubai, can also be used.

The water-solubilizing group on the surface of the water-dispersible pigment may be any of nonionic, cationic or anionic. Particularly, sulfonic acid, carboxylic acid, hydroxyl group, phosphorus group, Acids are preferred. In the case of sulfonic acid, carboxylic acid, and phosphoric acid, they can be used as they are in the form of a free acid. However, in order to enhance water solubility, it is preferable to use as a salt with a basic compound. In this case, as a basic compound, sodium, potassium, alkali metals such as lithium, monomethylamine, dimethylamine, aliphatic amines such as triethylamine, monomethanolamine, monoethanolamine,
Alcohol amines such as diethanolamine, triethanolamine and diisopropanolamine, ammonia and the like can be used. Among these, basic compounds of alkali metals such as sodium, potassium and lithium can be particularly preferably used. This is presumably because the basic compound of the alkali metal is a strong electrolyte and has a large effect of promoting the dissociation of the acidic group.

The content of these water-dispersible pigments in the ink is preferably 0.5 to 20% by weight, more preferably 2 to 10% by weight.
When the content of the pigment is less than 0.5% by weight, the optical density may be low. If it exceeds 20% by weight, the image fixing property may be deteriorated.

2. Anionic compound Examples of the anionic compound used in the ink of the recording material of the present invention include acids such as carboxylic acid and sulfonic acid and derivatives thereof, and α, β-ethylenically unsaturated monomers having an anionic group. Addition polymers, anionic surfactants, polymer emulsions and the like.

Examples of carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, lactic acid, tartaric acid, benzoic acid,
Acrylic acid, crotonic acid, butenoic acid, methacrylic acid, tiglic acid, allylic acid, 2-ethyl-2-butenoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, fumaric acid, methylmaleic acid, glyceric acid And their polymers, derivatives and the like. Further, alkali metal salts, alkaline earth metal salts, ammonium salts and the like of these compounds can also be used.

Examples of the sulfonic acid include benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, benzenedisulfonic acid, benzenetrisulfonic acid, hydroxybenzenesulfonic acid, chlorobenzenesulfonic acid, bromobenzenesulfonic acid, and 4-hydroxy-1. , 3-benzenedisulfonic acid, 4,5-dihydroxybenzene-1,
Examples thereof include sulfonic acids such as 3-disulfonic acid and o-aminobenzenesulfonic acid, and derivatives thereof, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof.

Examples of the addition polymer containing an α, β-ethylenically unsaturated monomer having an anionic group include a monomer having an α, β-ethylenically unsaturated group having an anionic group and an α, β having a hydrophobic group. A copolymer in which monomers having an ethylenically unsaturated group are appropriately combined, and a homopolymer of a monomer having an α, β-ethylenically unsaturated group having an anionic group.

The monomer having an α, β-ethylenically unsaturated group having an anionic group includes a carboxyl group,
A monomer having a sulfonic acid group, a hydroxyl group, a phosphate group, and the like;
For example, 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,
Examples include methacryloxyethyl phosphate, bismethacryloxyethyl phosphate, methacryloxyethylphenylacid phosphate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and the like.

On the other hand, monomers having an α, β-ethylenically unsaturated group having a hydrophobic group include styrene derivatives such as styrene, α-methylstyrene, vinyltoluene, vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives, and acrylic acid. Examples thereof include alkyl esters, phenyl acrylate, alkyl methacrylate, phenyl methacrylate, cycloalkyl methacrylate, alkyl crotonate, dialkyl itaconate, and dialkyl maleate.

Examples of preferred copolymers of these monomers include styrene-styrene sulfonic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, vinyl naphthalene -Maleic acid copolymer, vinyl naphthalene-methacrylic acid copolymer, vinyl naphthalene-acrylic acid copolymer, acrylic acid alkyl ester-acrylic acid copolymer, methacrylic acid alkyl ester-methacrylic acid, styrene-methacrylic acid alkyl ester -Methacrylic acid copolymer, styrene-alkyl acrylate-acrylic acid copolymer, styrene-phenyl methacrylate-methacrylic acid copolymer, styrene-cyclohexyl methacrylate-methacrylic acid copolymer and the like.

Further, a monomer having a polyoxyethylene group or a hydroxyl group may be appropriately copolymerized with these polymers, and a monomer having a cationic functional group, for example, N, N-dimethylaminoethyl methacrylate, N,
N-dimethylaminoethyl acrylate, N, N-dimethylaminomethacrylamide, N, N-dimethylaminoacrylamide, N-vinylpyrrole, N-vinylpyridine, N-vinylpyrrolidone, N-vinylimidazole and the like are appropriately copolymerized. Is also good. The copolymer may have any structure such as random, block and graft copolymers.

These polymers are preferably used in the form of a salt with a basic compound in order to increase the water solubility. Compounds that form salts with these polymers include alkali metals such as sodium, potassium and lithium, aliphatic amines such as monomethylamine, dimethylamine and triethylamine, monomethanolamine, monoethanolamine, diethanolamine and triethanol. Amine, alcohol amines such as diisopropanolamine, ammonia and the like can be used. Among these,
Basic compounds of alkali metals such as sodium, potassium and lithium are preferred. This is because a basic compound of an alkali metal is a strong electrolyte and has a large effect of promoting dissociation of an acidic group.

The anionic compound preferably has a structure consisting of a hydrophilic part and a hydrophobic part.
It is preferable that the hydrophilic functional group contains a carboxyl group. It is considered that this is because the carboxyl group forms a crosslinked structure with the polyvalent metal ion and becomes insoluble in water.
The monomer constituting the hydrophilic part of the anionic compound is preferably at least one selected from acrylic acid, methacrylic acid and (anhydride) maleic acid. The monomers constituting the hydrophobic part of the anionic compound are styrene, α
-Styrene derivatives such as methylstyrene and vinyltoluene, vinylcyclohexane, vinylnaphthalene, alkyl acrylate, alkyl methacrylate, phenyl methacrylate, cycloalkyl methacrylate, alkyl crotonate, dialkyl itaconate, maleic acid Dialkyl esters and the like can be used, and in particular, one or more selected from styrene, alkyl, aryl and alkylaryl esters of (meth) acrylic acid are preferable.

Preferred specific examples of the anionic compound include alkyl acrylate-acrylic acid copolymer, styrene-alkyl methacrylate-methacrylic acid copolymer, styrene-maleic acid copolymer and styrene-methacrylic acid copolymer. Polymer, styrene-acrylic acid copolymer, methacrylic acid alkyl ester-methacrylic acid, styrene-acrylic acid alkyl ester-acrylic acid copolymer, styrene-methacrylic acid phenyl ester-methacrylic acid copolymer, styrene-cyclohexyl methacrylate Ester-methacrylic acid copolymer and the like, and
Salts and derivatives of these copolymers are included.

The neutralization amount of the anionic compound is more preferably 50% or more with respect to the acid value of the copolymer, and more preferably 80% or more with respect to the oxidation of the copolymer. Is particularly preferred.

These anionic compounds may be used alone or in combination of two or more. The content of the anionic compound in the ink is preferably from 0.1 to 10% by weight, particularly preferably from 0.3 to 5% by weight. When the content of the anionic compound is 0.1% by weight
If it is less than 10% by weight, it may be inferior in long-term storage stability or the optical density may be reduced. If it exceeds 10% by weight, it may not be possible to jet normally or the optical density may be reduced.

3. Water-Soluble Organic Solvent The water-soluble organic solvent used in the ink in the recording material of the present invention may be the same as the water-soluble organic solvent used in the colorless or pale-colored solution described above.

The content of the water-soluble organic solvent in the ink is preferably 1 to 60% by weight, particularly preferably 5 to 40% by weight. When the content of the water-soluble organic solvent is less than 1% by weight, long-term stability may be poor. In addition, 60% by weight
Exceeding the range may cause a decrease in ejection stability, and may cause abnormal ejection.

4. Surfactant Examples of the surfactant used in the ink of the recording material of the present invention include various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, and the like.

Examples of the anionic surfactant include alkyl benzene sulfonate, alkyl phenyl sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt,
Higher fatty acid ester sulfate, higher fatty acid ester sulfonate, higher alcohol ether sulfate and sulfonate, higher alkyl sulfosuccinate, higher alkyl phosphate ester, higher alcohol ethylene oxide adduct phosphoric acid Ester salts and the like can be used, for example, dodecylbenzenesulfonate, kerylbenzenesulfonate, isopropylnaphthalenesulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, monobutylbiphenylsulfonate And dibutylphenylphenol disulfonate.

As the nonionic surfactant, for example,
Polypropylene glycol ethylene oxide adduct,
Polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester,
Examples include sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkylolamides, acetylene glycol, oxyethylene adducts of acetylene glycol, aliphatic alkanolamides, glycerin esters, sorbitan esters, and the like.

As the cationic surfactant, for example,
Tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts and the like, and specific examples thereof include dihydroxyethylstearylamine, 2-heptadecenyl-hydroxyethylimidazoline, lauryldimethyl Benzyl ammonium chloride, cetyl pyridinium chloride, stearamide methyl pyridium chloride and the like can be mentioned.

In addition, silicone surfactants such as polysiloxane oxyethylene adduct, fluorine surfactants such as perfluoroalkyl carboxylate, perfluoroalkyl sulfonate, oxyethylene perfluoroalkyl ether and the like, spikspol Biosurfactants such as acids, rhamnolipids, and lysolecithin can also be used.

Among these surfactants, a nonionic surfactant and a cationic surfactant are preferable, and acetylene glycol, an oxyethylene adduct of acetylene glycol, and polyoxyethylene alkyl ether are particularly preferable.

These surfactants can be used alone or
Mixtures of more than one species may be used. The weight average molecular weight of the surfactant is preferably less than 5,000, particularly preferably less than 2,000. When a polymer having a molecular weight of 5,000 or more is used, there is a polymer having a deteriorated image fixing property. This is considered to be due to a decrease in the penetrating power to the paper.

The content of the surfactant in the ink is 1
Preferably less than 0% by weight, 0.1 to 5% by weight
Is particularly preferred. When the addition amount is 10% by weight or more, the optical density may decrease.

4. Water Water used in the ink of the recording material of the present invention may be ion-exchanged water, distilled water, pure water, ultrapure water, or the like. The content of water in the ink is preferably 1 to 98% by weight, particularly preferably 40 to 93% by weight. 1
When the amount is less than the weight%, the ejection stability may be reduced, and the ejection may not be performed normally. If it exceeds 98% by weight, long-term storage stability may be poor.

5. Other Components 1) Property Control Agent For controlling the properties of the ink, the same one as described above as a property control agent for a colorless or pale color solution can be used. The content in these inks is 0.1 to 2
It is preferably 0% by weight.

2) Other Additives Further, if necessary, a pH buffer, an antioxidant, a fungicide, a viscosity modifier, a conductive agent, an ultraviolet absorber,
Chelating agents, water-soluble dyes, disperse dyes, oil-soluble dyes and the like can also be added. The content of these additives in the ink is preferably 20% by weight or less.

(Method for Producing Ink) The ink of the present invention comprises:
For example, a surface modification treatment is performed on the pigment, the obtained pigment is added to water, and after sufficient stirring, dispersion is performed by a disperser as necessary, and after removing coarse particles by centrifugation or the like, It can be obtained by adding a predetermined solvent, an additive and the like, stirring, mixing and filtering. The pigment may be pulverized before performing the surface modification treatment. Commercially available dispersers can be used, for example, colloid mills, flow jet mills, slasher mills, high-speed dispersers, ball mills, attritors, sand mills, sand grinders, ultra fine mills, Eiger motor mills, dyno mills, Pearl mills, agitator mills, Kobol mills, three rolls, two rolls, extruders, kneaders, microfluidizers, laboratory homogenizers, ultrasonic homogenizers, etc., and these may be used alone or in combination of two or more. You may. In order to prevent the contamination of inorganic impurities, it is preferable to use a dispersion method that does not use a dispersion medium. In this case, it is preferable to use a microfluidizer, an ultrasonic homogenizer, or the like. In the examples of the present invention, dispersion was performed with an ultrasonic homogenizer.

(PH of Ink) The pH of the ink which is a component of the recording material of the present invention is preferably from 3 to 11, particularly preferably from 4.5 to 9.5. In the case of an ink having an anionic free radical on the surface of a pigment, the pH of the ink is preferably 6 to 11, and is preferably 6 to 9.
It is more preferably set to 5, more preferably 7.5 to 9.0. On the other hand, in the ink having a cationic free radical on the pigment surface, the pH of the ink is preferably set to 4.5 to 8.0, and more preferably set to 4.5 to 7.0.

(Viscosity of Ink) The viscosity of the ink as a component of the recording material of the present invention is preferably 1.5 to 6.0 mPa · s, and more preferably 1.5 to 4.0 mPa · s. More preferred. If the viscosity of the ink is greater than 6.0 mPa · s, sufficient image fixability cannot be obtained. It is considered that this is because the penetrating power to the recording medium is reduced, and the pigment or the pigment aggregate remains near the recording medium surface. On the other hand, if the viscosity of the ink is less than 1.5 mPa · s, a sufficient optical density cannot be obtained. It is considered that this is because the penetrating power into the recording medium increases, and the pigment or the pigment aggregate penetrates into the recording medium.

(Number average particle diameter and volume average particle diameter of dispersed particles in ink) The number average particle diameter of the dispersed particles in the ink is preferably 15 to 100 nm, and 15 to 80 n.
m is more preferable, and 20 to 70 nm is further preferable.
The volume average particle diameter is preferably from 30 to 200 nm,
-170 nm is more preferable, and 30-150 nm is still more preferable. The number average particle diameter and volume average particle diameter of the dispersed particles in the ink are substantially those of the pigment in the ink.

When the number average particle diameter and the volume average particle diameter of the dispersed particles in the ink are within these ranges, the optical density is high and the image fixability is excellent. When the number average particle diameter of the dispersed particles in the ink is larger than 100 nm, or when the volume average particle diameter is larger than 200 nm, the optical density becomes poor. This means that as the dispersion particle size increases, the particle size of the pigment aggregates also increases,
It is considered that a sufficient optical density cannot be obtained. It is generally known that a pigment having a large primary particle size has a low coloring power. On the other hand, when the number average particle size of the dispersed particles in the ink is smaller than 15 nm, or when the volume average particle size is
If it is smaller than 0 nm, the viscosity of the ink becomes high, and nozzle clogging is likely to occur. In the present invention, the number average particle size and the volume average particle size were measured using a Microtrac UPA particle size analyzer 9340 (manufactured by Leeds & Northrup). This device measures the particle size using the Brownian motion of a dispersoid, and irradiates a solution with laser light and detects the scattered light to measure the particle size. In the present invention, the measurement is performed using 4 ml of ink.
Was put into a measurement cell, and the measurement was performed according to a predetermined measurement method. As parameters to be input at the time of measurement, the viscosity of the ink was input as the viscosity and the density of the pigment was input as the density of the dispersed particles.

[C] Recording Material of the Present Invention The recording material of the present invention comprises the above colorless or pale solution and ink.

In the recording material of the present invention, the number of particles of 0.5 μm or more present in 1 liter of the recording material is 1 × 10 ¹¹ or more, and the number of particles contained in 1 liter of the recording material is 5 μm or more.
The effect of the present invention can be obtained when the number of particles of m or more is required to be 1 × 10 ⁹ or more, and the particle diameter is in this range. 0.5 present in 1 liter of recording material
When the number of particles having a particle size of at least 1 μm is less than 1 × 10 ¹¹ or the number of particles having a particle size of 5 μm or more present in one liter of the recording material is less than 1 × 10 ⁹ , the image fixing property is satisfactory. However, there are cases where the optical density is lowered, and cases where the optical density is sufficient but the image fixability is poor.
Although the image fixing property is satisfactory, it is presumed that when the optical density is lowered, the aggregation of the pigment is insufficient, the particle diameter is small, and the pigment has penetrated into the recording medium by the action of the surfactant. You. On the other hand, in the case where the optical density is sufficient but the image fixing property is poor, it is presumed that the pigment aggregates became large and the aggregates became difficult to penetrate into the recording medium due to the large particle size. The number of particles of 0.5 μm or more present in 1 liter of the recording material is preferably 2.5 × 10
¹¹ , more preferably 5 × 10 ¹¹ recording material 1
The number of particles having a size of 5 μm or more present in a liter is preferably 5 × 10 ⁹ or more, more preferably 1 × 10 ¹⁰ or more.

In the present invention, the number of particles of 0.5 μm or more and the number of particles of 5 μm or more in the recording material are:
It was measured according to the following method. That is, both are weighed and mixed so that the ratio of the colorless or pale solution amount to the ink amount is 1: 1. While stirring this mixture, 2 μl was weighed, and Accusizer TM770 Op
physical ParticleSizer (Parti
cle Sizing Systems) is used as a measuring device to measure the number of particles. As a parameter to be input at the time of measurement, the density of the pigment was input as the density of the dispersed particles.

(Molar Ratio of Surfactant to Electrolyte in Recording Material) The molar ratio of surfactant to electrolyte in the recording material of the present invention is preferably 1: 1 to 1:15, and 1: 1 to 1:15.
10 is more preferable, and 1: 2 to 1: 8 is still more preferable. If the molar ratio between the surfactant and the electrolyte is greater than 1:15, the optical density will be poor. This is probably because the effect of aggregating the pigment is greater than the effect of permeating the pigment or the pigment aggregate. on the other hand,
When the molar ratio between the surfactant and the electrolyte is less than 1: 1, sufficient image fixability cannot be obtained. This is presumably because the effect of penetrating the pigment or the pigment aggregate is greater than the effect of aggregating the pigment. In the present invention, the molecular weight of the surfactant is represented by a weight average molecular weight measured by a GPC (gel permeation chromatography) method.

(Image Forming Method) An image can be formed by recording using the recording material of the present invention by a thermal ink jet recording method.

As a recording apparatus that can be used for image formation, not only an ordinary ink jet recording apparatus but also a recording apparatus equipped with a heater for controlling ink drying, or an intermediate transfer mechanism is used. It is also possible to use a recording device or the like that mounts, prints a recording material on an intermediate, and then transfers it to a recording medium such as paper.

The application of the colorless or light-colored solution and the ink may be simultaneous. However, the ink may be applied to the recording medium after the colorless or light-colored solution is applied to the recording medium, or the ink may be applied to the recording medium. After that, a colorless or pale-colored solution may be adhered to the recording medium. The ratio of the colorless or light-colored solution to the amount of ink applied is preferably in the range of 2: 1 to 1:10. If the amount of the colorless or pale solution is less than 1/10 times the amount of the applied ink, the effect of the present invention cannot be sufficiently obtained. If the amount of the colorless or light-colored solution is more than twice the amount of the applied ink, the paper curls and cuckles.

Using the recording material of the present invention, an image area ratio of 1
The effect of the present invention can be obtained when the drying time when printing a 00% solid image on FX-L paper (manufactured by Fuji Xerox Co., Ltd.) is 5 seconds or less (see Examples and Comparative Examples below). ). If the drying time is longer than 5 seconds,
Although the optical density can be sufficiently obtained, there are some which have poor image fixability. This is presumed to be due to insufficient penetration of the pigment aggregate into the recording medium due to a small penetration effect. The drying time was measured by pressing blank FX-L paper against the printing surface with a load of 9.8 × 10 ³ N / m ² , and measuring the time until the ink stopped transferring to the blank FX-L paper side. It was done by doing.

The recording material of the present invention can be used in combination with a dye ink or the like at the time of full-color recording or the like, and the colorless or light-colored solution constituting the recording material of the present invention is superimposed on the dye ink. It is also possible to use.

[0082]

Since the recording material of the present invention uses a self-dispersible pigment, the ink according to the present invention has the following 1 to 3 in comparison with an ink in which a pigment is dispersed using a dispersant. It has advantages.

1. In an ink in which a pigment is dispersed using a dispersant, the dispersant detaches from the pigment surface over time, and thus tends to have poor long-term storage stability. On the other hand, in the ink according to the present invention, since the ionizing group is chemically bonded to the pigment surface, the surface charge hardly changes over time, and the ink has excellent long-term storage stability.

2. In an ink in which a pigment is dispersed by using a dispersant, it is necessary to select a dispersant that is easily adsorbed by the pigment, so that the molecular weight and composition of the dispersant are restricted. However, in the ink according to the present invention, since the dispersant does not need to be used, the molecular weight, composition, and the like of the anionic compound can be freely selected.

3. In an ink in which a pigment is dispersed by using a dispersant, when a large amount of a surfactant is added, the pigment may agglomerate. For example, the replacement of the surfactant with the dispersant occurs. This is considered to be due to the fact that the electrostatic repulsion is weakened by the action of. On the other hand, in the ink according to the present invention, even if a large amount of a surfactant is added, the dispersion stability of the pigment is not affected, and the long-term storage stability is excellent. This is the case with inks that use self-dispersible pigments.
It is considered that the ionizing group is chemically bonded to the pigment surface and the surface charge is not replaced by the surfactant.

In the ink according to the present invention, the pigment is mainly composed of the ink and a colorless or pale color solution because the dispersion stability is maintained by the action of electrostatic repulsion by free radicals on the surface of the pigment. It is presumed that the following phenomena 1 to 4 occur in the recording material of the present invention.

1. The effect of the electrolyte contained in the colorless or pale-colored solution weakens the electrostatic repulsion of the pigment and causes the pigment to aggregate. In particular, when the electrolyte is a polyvalent metal, the attenuation of the electrostatic repulsion is remarkable, and the aggregation of the pigment is accelerated.

2. The function of the electrolyte contained in the colorless or pale solution makes the anionic compound water-insoluble. In particular, when the electrolyte is a polyvalent metal and a carboxyl group is contained in the anionic compound, the carboxyl group and the polyvalent metal form a crosslinked structure, and thus are easily water-insoluble.

3. Aggregates of the pigment and the anionic compound are formed by the above actions 1 and 2.

4. Due to the surfactant contained in the recording material, the above-mentioned aggregates permeate into the recording medium. By controlling the behavior of this aggregation and permeation, it is possible to simultaneously achieve high optical density and good image fixability, but the control is based on the relationship between the particle diameter and the number of particles in the recording material described above, It can be carried out by adjusting the conductivity of the colorless or light-colored solution, the number average particle diameter of the dispersed particles in the ink, the volume average particle diameter, the viscosity of the ink, and the like.

[0091]

Embodiments of the present invention will be described below in detail. [Method for producing colorless or pale solution] The following components were mixed and dissolved, and then filtered through a 0.45 µm filter to obtain colorless or pale solutions A to J.

[Colorless or pale solution-A] Diglycerin ethylene oxide adduct 10 parts by weight Calcium nitrate tetrahydrate 3 parts by weight Isopropyl alcohol 3 parts by weight Deionized water balance The remaining 100 parts by weight The obtained colorless or pale solution Has a conductivity of 1.3 S / m
Met.

[Colorless or pale-colored solution-B] Diethylene glycol monobutyl ether 10 parts by weight Magnesium acetate tetrahydrate 1 part by weight Urea 3 parts by weight Deionized water balance The remaining 100 parts by weight The conductivity of the obtained colorless or pale-colored solution is as follows. , 0.8S / m
Met.

[Colorless or pale-colored solution-C] Diethylene glycol 10 parts by weight Calcium nitrate tetrahydrate 10 parts by weight Urea 3 parts by weight Deionized water balance The remaining 100 parts by weight The obtained colorless or pale-colored solution has a conductivity of 3 parts. .3S / m
Met.

[Colorless or pale-colored solution-D] Diglycerin ethylene oxide adduct 10 parts by weight Calcium nitrate tetrahydrate 0.3 part by weight Ion-exchanged water balance 100 parts by weight Total conductivity of the obtained colorless or pale-colored solution Is 0.15S /
m.

[Colorless or Pale Color Solution-E] Diglycerin ethylene oxide adduct 10 parts by weight Benzalkonium chloride 1.5 parts by weight Ion-exchanged water balance 100 parts by weight The obtained colorless or pale color solution has a conductivity of 0. .8S / m
Met.

[Colorless or pale solution-F] Glycerin 10 parts by weight Sodium chloride 3 parts by weight Isopropyl alcohol 3 parts by weight Ion-exchanged water balance 100 parts by weight The obtained colorless or pale solution has a conductivity of 3.5 S / m.
Met.

[Colorless or pale-colored solution-G] Diethylene glycol 10 parts by weight Polyallylamine (PAA-HCl-10L / manufactured by Nitto Boseki) 5 parts by weight Ion-exchanged water Remainder 100 parts by weight Total conductivity of the obtained colorless or pale-colored solution Is 0.5 S / m
Met.

[Colorless or pale solution-H] Propylene glycol 10 parts by weight Zinc sulfate heptahydrate 3 parts by weight Potassium benzoate 1 part by weight Surfactant (Nonion E-215 / manufactured by NOF Corporation) 0.03 parts by weight Parts Isopropyl alcohol 3 parts by weight Urea 3 parts by weight Ion-exchanged water Remainder Total 100 parts by weight The obtained colorless or pale solution has a conductivity of 1.6 S / m.
Met.

[Colorless or pale solution-I] Thiodiethanol 10 parts by weight Magnesium nitrate hexahydrate 2.5 parts by weight Sodium acetate trihydrate 1 part by weight Isopropyl alcohol 3 parts by weight Ion-exchanged water balance 100 parts in total Part The conductivity of the obtained colorless or pale solution is 1.5 S / m
Met.

[Colorless or pale solution-J] Diethylene glycol 10 parts by weight Magnesium chloride hexahydrate 1 part by weight Calcium acetate monohydrate 1 part by weight Sodium lactate 1 part by weight Surfactant (Nonipol 95 / Sanyo Chemical Co., Ltd.) 0.03 parts by weight Isopropyl alcohol 3 parts by weight Urea 3 parts by weight Ion-exchanged water Remainder Total 100 parts by weight The obtained colorless or pale solution has a conductivity of 2.0 S / m.
Met.

Hereinafter, methods 1 to 3 for dispersing the pigment will be described. [Pigment dispersion method 1] A pigment dispersion liquid subjected to a centrifugal separation treatment (8000 rpm x 30 minutes) with a centrifugal separator to remove a residual portion (20% of the total amount) was used.

[Pigment Dispersion Method 2] The pigment subjected to the plasma treatment was added to ion-exchanged water such that the pigment concentration became 20 wt%, and dispersed using a high-pressure homogenizer. This dispersion is centrifuged (80
(00 rpm × 30 minutes) to remove a residue portion (20% of the total amount).

[Pigment Dispersion Method 3] The pigment was subjected to a surface oxidation treatment with sodium hypochlorite, followed by a desalting treatment. The surface-treated pigment thus obtained was added to ion-exchanged water so as to have a pigment concentration of 20 wt%, the pH was adjusted to 7.5, and then dispersed using an ultrasonic homogenizer. This dispersion was subjected to a centrifugal separation treatment (8000 rpm × 30 minutes) with a centrifugal separator to remove a residue portion (20% of the total amount).

[Ink Production Method] A total of 100 parts by weight of a pigment, an anionic compound, a water-soluble organic solvent, a surfactant, water, and the like, which are self-dispersible in water, as described below, is used so that the pigment concentration becomes a predetermined concentration. After mixing, stirring and passing through a 1 μm filter, desired inks A to M were obtained.

[Ink-A] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 1 and the above-mentioned ink production method. Carbon black (Cab-o-jet-300 / Cabot) 4 parts by weight Styrene-methacrylic acid-sodium methacrylate copolymer 1 part by weight Diethylene glycol 10 parts by weight Diglycerin ethylene oxide adduct 5 parts by weight Surfactant (Pluronic PE6400 / BASF) 5 parts by weight Isopropyl alcohol 3 parts by weight Ion-exchanged water balance 100 parts by weight The obtained ink had a number average particle diameter of 43 nm, a volume average particle diameter of 88 nm, and a viscosity of 2.4 mPa · s.

[Ink-B] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 1 and the above-mentioned ink production method. Carbon black (Microjet Black CW1 / manufactured by Orient) 4 parts by weight 2-ethylhexyl methacrylate-maleic acid-sodium maleate copolymer 1 part by weight Propylene glycol 15 parts by weight Surfactant (Surfinol 465 / Nissin Chemical Co., Ltd.) 1.5 parts by weight Isopropyl alcohol 3 parts by weight Urea 3 parts by weight Ion-exchanged water Remainder Total 100 parts by weight The obtained ink had a number average particle diameter of 29 nm, a volume average particle diameter of 45 nm, and a viscosity of 2.3 mPa · s.

[Ink-C] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 1 and the above-mentioned ink production method. Carbon black (Cab-o-jet-300 / Cabot) 4 parts by weight Polyacrylic acid 1 part by weight Diethylene glycol 10 parts by weight Diglycerin ethylene oxide adduct 5 parts by weight Surfactant (Nonipol 95 / manufactured by Sanyo Chemical Industries) 2 Parts by weight isopropyl alcohol 3 parts by weight ion-exchanged water balance 100 parts by weight The obtained ink had a number average particle diameter of 45 nm, a volume average particle diameter of 90 nm, and a viscosity of 2.5 mPa · s.

[Ink-D] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 1 and the above-mentioned ink production method. Carbon black (Microjet Black CW1 / Orient) 5 parts by weight Glycerin 15 parts by weight Surfactant (Nonion E-230 / Nippon Oil & Fats) 1.5 parts by weight Isopropyl alcohol 3 parts by weight Urea 3 parts by weight Deionized water balance Total 100 parts by weight The obtained ink had a number average particle diameter of 27 nm, a volume average particle diameter of 41 nm, and a viscosity of 2.6 mPa · s.

[Ink-E] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 1 and the above-mentioned ink production method. Carbon black (Cab-o-jet-300 / Cabot) 5 parts by weight Styrene-methacrylic acid-sodium methacrylate copolymer 1 part by weight Glycerin 15 parts by weight Surfactant (Pluronic PE6400 / BASF) 4 parts by weight Isopropyl alcohol 3 parts by weight Sodium chloride 0.5 part by weight Ion-exchanged water Remainder 100 parts by weight The obtained ink had a number average particle diameter of 105 nm, a volume average particle diameter of 203 nm, and a viscosity of 3.1 mPa · s.

[Ink-F] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 1 and the above-mentioned ink production method. Carbon black (Microjet Black CW-1 / manufactured by Orient) 5 parts by weight Styrene-methacrylic acid-sodium methacrylate copolymer 1 part by weight Surfactant (Nonion E-215 / Nippon Yushi Co., Ltd.) 3 parts by weight Urea 3 parts by weight Part ion-exchanged water balance 100 parts by weight in total The obtained ink had a number average particle diameter of 14 nm, a volume average particle diameter of 28 nm, and a viscosity of 1.4 mPa · s.

[Ink-G] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 1 and the above-mentioned ink production method. Carbon black (Cab-o-jet-300 / Cabot) 5 parts by weight Styrene-methacrylic acid-sodium methacrylate copolymer 1 part by weight Diethylene glycol 10 parts by weight Thiodiethanol 5 parts by weight Isopropyl alcohol 3 parts by weight Urea 3 parts by weight Ion-exchanged water balance: 100 parts by weight The obtained ink had a number average particle diameter of 47 nm, a volume average particle diameter of 95 nm, and a viscosity of 2.6 mPa · s.

[Ink-H] According to the above-mentioned pigment dispersion method 2 and the above-mentioned ink production method, an ink having the following composition was obtained. Surface treated pigment (CIPigment Blue 15: 3) 4 parts by weight Styrene-acrylic acid-potassium acrylate copolymer 1.5 parts by weight Diglycerin ethylene oxide adduct 5 parts by weight Sulfolane 5 parts by weight Surfactant (Nonion E-215) 3 parts by weight ion-exchanged water balance 100 parts by weight The obtained ink had a number average particle diameter of 69 nm, a volume average particle diameter of 138 nm, and a viscosity of 2.8 mPa · s.

[Ink-I] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 3 and the above-mentioned ink production method. Surface treatment pigment (CIPigment Blue 15: 3) 4 parts by weight 2-ethylhexyl methacrylate-acrylic acid-potassium acrylate copolymer 1.5 parts by weight Diethylene glycol 5 parts by weight Glycerin 5 parts by weight Sulfolane 5 parts by weight Surfactant (Nonion E) -230 / manufactured by NOF Corporation 3 parts by weight Ion-exchanged water balance 100 parts by weight The obtained ink had a number average particle diameter of 72 nm, a volume average particle diameter of 145 nm, and a viscosity of 2.7 mPa · s.

[Ink-J] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 2 and the above-mentioned ink production method. Surface treated pigment (CIPigment Red 122) 4 parts by weight Polyacrylic acid 1 part by weight Thiodiethanol 15 parts by weight Triethylene glycol monobutyl ether 5 parts by weight Surfactant (Pluronic PE65 / BASF) 3 parts by weight Ion-exchanged water balance 100 in total Part by weight The obtained ink had a number average particle diameter of 70 nm, a volume average particle diameter of 140 nm, and a viscosity of 2.7 mPa · s.

[Ink-K] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 3 and the above-mentioned ink production method. Surface treated pigment (CIPigment Yellow 17) 4 parts by weight Styrene-maleic acid-sodium maleate copolymer 1.5 parts by weight Diethylene glycol 10 parts by weight Propylene glycol 5 parts by weight Thiodiethanol 5 parts by weight Surfactant (Surfinol 485 / day) 3 parts by weight Ion-exchanged water balance 100 parts by weight The obtained ink had a number average particle diameter of 74 nm, a volume average particle diameter of 144 nm, and a viscosity of 2.7 mPa · s.

[Ink-L] An ink having the following composition was obtained according to the above-mentioned pigment dispersion method 3 and the above-mentioned ink production method. Surface treated pigment (MA100 / Mitsubishi Chemical Corporation) 5 parts by weight Styrene-styrene sulfonic acid-methacrylic acid block copolymer sodium neutralized salt 1.5 parts by weight Thiodiethanol 15 parts by weight Thiourea 3 parts by weight Surfactant (Nonipol) 95 / manufactured by Sanyo Chemical Industries, Ltd. 3 parts by weight Ion-exchanged water balance 100 parts by weight The obtained ink had a number average particle diameter of 45 nm, a volume average particle diameter of 89 nm, and a viscosity of 2.8 mPa · s.

[Ink-M] According to the above-mentioned pigment dispersion method 2 and the above-mentioned ink production method, an ink having the following composition was obtained. Surface treated pigment (Monarch 880 / Cabot Co.) 5 parts by weight Styrene-maleic acid-sodium maleate copolymer 2 parts by weight Diethylene glycol 15 parts by weight Propylene glycol monobutyl ether 5 parts by weight t-butyl alcohol 1.5 parts by weight Surface activity 3 parts by weight of urea 3 parts by weight of ion-exchanged water balance 100 parts in total The obtained ink has a number average particle diameter of 51 nm, a volume average particle diameter of 92 nm, and a viscosity of 3.0 mPa · s. Met.

(Examples 1 to 21) Recording materials of the present invention were obtained by combining the colorless or light-colored solutions and inks shown in Tables 1 and 2.

(Comparative Examples 1 to 14) Recording materials were obtained by combining the colorless or light-colored solutions and inks shown in Table 3.

(Test Example 1) The recording materials obtained in Examples 1 to 21 and Comparative Examples 1 to 14 were evaluated as follows.

The printing device has a resolution of 400 dpi, 16 dpi.
Using a zero-nozzle prototype printhead, printing was performed by ejecting a colorless or pale solution and ink. FX-L paper (manufactured by Fuji Xerox Co., Ltd.) was used as a recording medium. Unless otherwise specified, printing and evaluation were performed in a general environment (temperature: 23 ± 0.5 ° C., humidity: 55 ± 5% RH).

1) Evaluation of Drying Time A trial ink cartridge was filled with the evaluation ink, and an image area ratio of 100 was measured using the trial inkjet recording apparatus.
% Solid image on FX-L paper (Fuji Xerox Co., Ltd.)
Printed on top. 9.8 blank FX-L paper is printed on this printing surface.
Pressing with a load of × 10 ³ N / m ²
-The time until the transfer to the L paper side was stopped was measured and defined as the drying time.

2) Evaluation of Optical Density / Fixing Strength A trial ink cartridge was filled with the evaluation ink set,
A 100% coverage pattern was printed using a prototype ink jet recording apparatus, and left for 24 hours in a general environment.
Using this recorded material, the optical density and the fixing strength were evaluated. The optical density was measured using X-Rite 4
04 (manufactured by X-Rite Co., Ltd.).
Less than was evaluated as x.

[0125] The fixing strength was determined by using the FX-
The L paper was pressed with a load of 4.9 × 10 ⁴ N / m ² , and the ink transferred to the blank FX-L paper was collated with a predetermined limit sample and evaluated by sensory evaluation. .

3) Evaluation of ejection characteristic stability Regarding the evaluation of ejection characteristic stability, after printing a colorless or pale solution and ink at 1 × 10 ⁸ pulse, 1
A 00% coverage pattern was printed, and the optical density in the initial printing and the optical density after 1 × 10 ⁸ pulse printing were measured. When the change amount of the optical density before and after 1 × 10 ⁸ pulse is ± 5% or less, the result is ○.
Was evaluated.

4) Evaluation of long-term storage stability The long-term storage stability was evaluated as follows. That is, the cartridge is filled with a colorless or pale solution and ink, and the cartridge is mounted on the ink jet recording apparatus. In this state, it was left for 3 months in an environment of 40 ° C. and 50 RH. This was printed under normal use conditions, and the one that could be printed with all nozzles was marked with ○. The one that was printed out under normal use conditions, the one that could be printed with all nozzles by repeating vacuum maintenance, was marked with △. When a nozzle that did not recover by itself alone was generated, it was evaluated as x. Tables 1 to 3 show these results.

[0128]

[Table 1]

[0129]

[Table 2]

[0130]

[Table 3]

As is clear from the results shown in Tables 1 to 3, when the recording materials obtained in Examples 1 to 21 were used, the drying time was all less than 5 seconds, and the optical density,
The image fixing property, the ejection characteristic stability and the long-term storage stability were excellent. In addition, when the recording materials obtained in Comparative Examples 1 to 14 were used, it was not possible to obtain a material having all excellent characteristics.

[0132]

As described above, according to the present invention,
A recording material exhibiting a high optical density, having excellent image fixing properties, and having excellent long-term storage stability and ejection characteristic stability, and an image forming method using the same can be obtained.

Claims (17)

[Claims] 1. A colorless or pale-colored solution containing an electrolyte, a water-soluble organic solvent and water, and an ink containing a water-dispersible pigment, an anionic compound, a water-soluble organic solvent, a surfactant and water. In a recording material composed of the following, the number of particles of 0.5 μm or more present in 1 liter of the recording material is 1 × 10 ¹¹ or more, and the number of particles of 5 μm or more is 1 × 10 ⁹ or more. Characteristic recording material. 2. The recording material according to claim 1, wherein the drying time when a solid image having an image area ratio of 100% is printed on plain paper is 5 seconds or less. 3. The recording material according to claim 1, wherein the electrolyte in the colorless or light-colored solution is a polyvalent metal salt, an alkali metal salt, or a cationic substance. 4. The recording material according to claim 1, wherein the electrolyte in the colorless or pale solution is a polyvalent metal salt. 5. The recording material according to claim 1, wherein the molar ratio between the surfactant and the electrolyte in the recording material is from 1: 1 to 1:15. 6. The recording material according to claim 1, wherein the number average particle diameter of the pigment dispersed particles in the ink is 15 to 100 nm, and the volume average particle diameter is 30 to 200 nm. 7. The conductivity of the colorless or pale solution is:
2. The recording material according to claim 1, wherein the recording material is within a range of 0.5 to 3.0 S / m. 8. The ink having a viscosity of 1.5 to 6.0 mP.
2. The recording material according to claim 1, wherein the recording material is a · s. 9. The recording material according to claim 1, wherein the anionic compound in the ink comprises a hydrophilic part and a hydrophobic part, and contains a carboxyl group as a hydrophilic functional group. 10. The monomer constituting the hydrophilic part of the anionic compound is at least one selected from acrylic acid, methacrylic acid and (anhydride) maleic acid. The recording material described. 11. The monomer constituting the hydrophobic part of the anionic compound is at least one selected from styrene, alkyl, aryl and alkylaryl esters of (meth) acrylic acid. Item 10. A recording material according to Item 9. 12. The recording material according to claim 1, wherein the water-dispersible pigment is carbon black. 13. The recording material according to claim 1, wherein the water-dispersible pigment is a color pigment. 14. The recording material according to claim 1, wherein the colorless or light-colored solution contains a carboxylic acid or a salt of a carboxylic acid. 15. An image forming method using the recording material according to claim 1 for recording by a thermal ink jet recording method. 16. The image forming method according to claim 15, wherein after the colorless or light-colored solution is applied to the recording medium, the ink is applied to the recording medium. 17. The image forming method according to claim 15, wherein a colorless or pale solution is applied to the recording medium after the ink is applied to the recording medium.