JP2003292836A - Ink and inkjet recording process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink which can give a metallically lustrous recording and can achieve a highly weather-resistant recording, and to provide an inkjet recording process using the same. <P>SOLUTION: The ink contains metallic microparticles dispersed in a liquid medium as the colorant. The inkjet recording process uses the ink. The metallic microparticles are colloidal metal particles produced by reducing a metal compound into the metal in a solution containing the metal compound and a polymer dispersant with groups having an affinity to the pigment in the main chain and/or a plurality of side chains. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink and an ink jet recording method using the ink. More specifically, the present invention relates to an ink containing metal fine particles as a coloring material and an inkjet recording method using the ink.

[0002]

2. Description of the Related Art In recent years, various inventions have been proposed for an ink jet recording method, and the fields of application of the ink jet recording method are now widespread. As a result, ink jet printers are widely used by users, and high performance such as high speed recording and high image quality is achieved. However, it is also true that there is a further demand for additional functions of the user's inkjet recording method.

Among them, a recorded matter having a metallic luster, that is, a so-called gold-silver foil pressing ink is included. At present, in order to achieve a printed matter having a metallic luster, black, cyan, magenta, and yellow inks in which an organic dye or an organic pigment is used as a coloring material are artificially expressed. However, it is fundamentally difficult to achieve the texture unique to metallic luster. On the other hand, if fine metal particles are used as a coloring material, a texture unique to metallic luster may be obtained. Colloidal particles of a metal are mentioned as one of the coloring materials of ink jet ink.

However, conventional inks using metal colloidal particles are those in which metal colloidal particles are agglomerated with each other, or the concentration of metal colloidal particles is low, so that sufficient image density cannot be obtained, Since the particle size distribution of the colloidal particles was wide, the saturation was low and it was not sufficient as a coloring material. Therefore, the conventional metal colloidal particles have good inkjet suitability, and there has been virtually no proposal that they are used as a coloring material for finely recorded images.

Further, the requirements for weather resistance (light resistance, gas resistance, water resistance, moisture resistance, etc.) of recorded matter are gradually increasing and becoming severer. Therefore, under the present circumstances, it is now an essential condition for inkjet inks to completely secure these required characteristics. However, although proposals have been made to improve the light resistance and gas resistance of conventional ink jet recorded matter, they are still insufficient.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ink capable of obtaining a high-definition color and metallic glossy recorded matter, and further a highly weather-resistant recorded matter, and an ink jet using the same. It is to provide a recording method.

[0007]

The above object can be achieved by the present invention described below. That is, the present invention provides an ink characterized by containing fine metal particles dispersed in a liquid medium as a coloring material.

In the above ink, the metal fine particles are colloidal particles of metal; the metal of the metal fine particles is a noble metal or copper; the noble metal is at least one selected from the group consisting of gold, silver and platinum. A polymer dispersant is contained as a dispersant for the metal fine particles; the metal fine particles dissolve the metal compound in a solvent containing the polymer dispersant, or after the metal compound is dissolved in the solvent. It is preferable that the metal colloidal particles are produced by reducing the metal compound to a metal in a solution prepared by adding a polymer dispersant to the solution.

Further, the polymer dispersant has the following (i) to
(Iii) a comb structure having a pigment affinity group on at least one of the main chain and a plurality of side chains, and having a plurality of side chains forming a solvation portion. Polymer having (ii) a plurality of pigment-affinity moieties having a pigment-affinity group in the main chain, (iii) a straight chain having a pigment-affinity moiety having a pigment-affinity group at one end of the main chain Macromolecule. The polymer (i) has 2 to 3,000 pigment-affinity groups in one molecule and 2 to 1,000 side chains constituting a solvation portion in one molecule, and The number average molecular weight is 2,000 to 1,000,000, and (ii)
The polymer has a pigment affinity group of 2 to 3,000 in one molecule.
And have a number average molecular weight of 2,000 to 1,000,000
0, and the polymer (iii) has a pigment-affinity group of 1
It has 2 to 3,000 in the molecule and has a number average molecular weight of 1,0.
0 to 1,000,000; the metal colloid is obtained by dissolving a metal compound in a solvent, adding a polymer dispersant, and then reducing the compound; It is preferable that the medium is water or a mixture of water and a water-soluble organic solvent; and that the ink is for inkjet recording. Further, the present invention provides an ink jet recording method, which comprises a step of ejecting ink from an orifice according to a recording signal.

Colloids of metals, especially precious metals and copper, are chemically very stable and develop a color unique to each colloid. Among the metal colloids, gold colloids show colors such as blue, bluish purple, and magenta depending on the particle size.

Coloring due to a noble metal colloid such as gold colloid is observed in so-called nanoparticles having a particle size of several nm to several tens of nm, which is caused by plasma vibration of electrons and is caused by a coloring mechanism called plasmon absorption. Is. Coloring due to this plasmon absorption causes free electrons in the metal to be shaken by an optical electric field, and electric charges appear on the particle surface.
It is said that this is because non-linear polarization occurs. Coloring with this noble metal colloid has high saturation and light transmittance, and is excellent in durability and the like.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. In the present specification, "printing" (also sometimes referred to as "recording" or "printing") is not limited to the case where significant information such as characters and figures is formed, and it does not matter whether it is significant or insignificant. In the case of forming images, patterns, patterns, etc. on a wide range of print media, regardless of whether or not they are visible so that they can be visually perceived,
Or, it means a case where the print medium is processed.

The term "print medium" (sometimes referred to as "recording medium") is not limited to paper used in a general printing apparatus, but is widely used as cloth, plastic film, metal plate, glass, ceramics. , Wood, leather, etc.
The term "paper" or simply "paper" will be used hereinafter, although the term "acceptable to ink" is also used.

Further, "ink" (which may be referred to as "liquid") should be broadly interpreted in the same manner as the definition of "print", and when applied to a print medium, an image, A liquid used for forming a pattern, a pattern, etc., processing a print medium, or treating an ink (for example, solidifying or insolubilizing a coloring material in the ink applied to the print medium).

The ink of the present invention is characterized by containing fine metal particles as a coloring material. The metal of the metal fine particles is not particularly limited, but examples thereof include noble metal, copper, aluminum, nickel, iron and zinc. Examples of the noble metal include gold, silver, ruthenium, rhodium, palladium, osmium, iridium,
Platinum and the like can be mentioned, among which gold, silver and platinum are preferable.

The fine metal particles may be finely divided by pulverization or the like, but metal colloid particles are preferable in view of the particle diameter and dispersion stability of the fine metal particles. Further, the metal colloidal particles can be produced by various methods. Considering the dispersion stability of the colloidal particles in the ink, whether the metal fine particles dissolve the metal compound in the solvent containing the polymer dispersant. Alternatively, the metal colloidal particles are preferably produced by dissolving the metal compound in a solvent and then adding a polymer dispersant to the solution to reduce the metal compound to a metal.

The compound of the above metal is not particularly limited as long as it contains the above metal, and examples thereof include chloroauric acid, silver nitrate, silver acetate, silver perchlorate, chloroplatinic acid, potassium chloroplatinate, and copper chloride ( II), copper acetate (II), copper sulfate (II) and the like.

The polymer dispersant is preferably an amphipathic copolymer in which a functional group having a high affinity for the pigment surface is introduced into the polymer. The polymer dispersant is suitable as a dispersant for organic pigments or inorganic pigments because it has sufficient compatibility with conventional resin compositions for paints, etc. It is used as a dispersant. Also in the present invention, it is effective as a dispersant for metal fine particles.

The polymer dispersant is not particularly limited, but those described below can be preferably used. That is: (1) a comb-shaped polymer having a pigment-affinity group on at least one of the main chain and a plurality of side chains and having a plurality of side chains constituting a solvation portion, (2) in the main chain A polymer having a plurality of pigment-affinity moieties consisting of a pigment-affinity group, and (3) a linear polymer having a pigment-affinity moiety comprising a pigment-affinity group at one end of the main chain.

Here, the pigment-affinitive group means a functional group having a strong adsorptive power to the surface of the pigment, for example,
In organosol, tertiary amino group, quaternary ammonium, heterocyclic group having basic nitrogen atom, hydroxyl group, carboxyl group; in hydrosol, phenyl group, lauryl group, stearyl group, dodecyl group, oleyl group, etc. Can be mentioned. In the present invention, the pigment-affinitive group has a strong affinity for metals. Since the polymer dispersant has the pigment-affinitive group, it can exhibit sufficient performance as a metal protective colloid.

The above-mentioned comb-shaped polymer (1) has a structure in which a plurality of side chains having the pigment-affinitive group and a plurality of side chains constituting a solvation part are bonded to the main chain.
These side chains are attached to the main chain as if they were comb teeth. In the present specification, the above structure is referred to as a comb structure. In the polymer (1) having the comb structure, the pigment-affinity group may be present not only at the side chain terminal but also in the middle of the side chain or in the main chain. The solvation part is
A portion having an affinity for a solvent, which is a hydrophilic or hydrophobic structure. The solvating portion is composed of, for example, a water-soluble polymer chain, a lipophilic polymer chain, or the like.

The polymer (1) having the comb structure is not particularly limited, and for example, one or more poly (carbonyl-C3 to C) disclosed in JP-A-5-177123.
6-alkyleneoxy) chains, each of these chains having 3 to
A poly (ethyleneimine) having a structure having 80 carbonyl-C3-C6-alkyleneoxy groups and having a structure linked to poly (ethyleneimine) by an amide or salt bridging group, or an acid salt thereof; Showa 54-3708
It comprises a reaction product of a poly (lower alkylene) imine disclosed in Japanese Patent Publication No. 2 and a polyester having a free carboxylic acid group, and at least two polyester chains are bonded to each poly (lower alkylene) imine chain. Japanese Patent Publication No. 7-24746, a high molecular weight epoxy compound having an epoxy group at the terminal, an amine compound and a carboxyl group-containing prepolymer having a number average molecular weight of 300 to 7,000, simultaneously or in any order. Examples thereof include pigment dispersants obtained by the reaction.

The comb-shaped polymer (1) preferably has 2 to 3,000 pigment-affinitive groups in one molecule. When it is less than 2, the dispersion stability is not sufficient,
If it exceeds 3,000, the viscosity will be too high and handling will be difficult, and the particle size distribution of the colloidal particles will be wide,
Saturation decreases. More preferably, it is 25-1,500.

The comb-shaped polymer (1) preferably has 2 to 1,000 side chains constituting the solvation portion in one molecule. When it is less than 2, the dispersion stability is not sufficient, and when it exceeds 1,000, the viscosity is too high and the handling becomes difficult, and the particle size distribution of the colloidal particles becomes wide, and the saturation decreases. More preferably 5-5
00.

The polymer (1) having a comb structure preferably has a number average molecular weight of 2,000 to 1,000,000. When it is less than 2,000, the dispersion stability is not sufficient, and when it exceeds 1,000,000, the viscosity becomes too high and the handling becomes difficult, and the particle size distribution of the colloidal particles becomes broad and the saturation decreases. To do. More preferably, 4,
It is 000 to 500,000.

The copolymer (2) having a plurality of pigment-affinity moieties composed of pigment-affinity groups in the main chain has a plurality of pigment-affinity groups arranged along the main chain. The pigment-affinitive group is, for example, one pendant to the main chain. In the present specification, the pigment-affinity portion means a portion having one or a plurality of the pigment-affinity groups and functioning as an anchor adsorbed on the pigment surface.

The above-mentioned copolymer (2) is, for example, a mixture of a polyisocyanate disclosed in JP-A-4-210220, a monohydroxy compound and a monohydroxymonocarboxylic acid or a monoaminomonocarboxylic acid compound, And a reaction product of a compound having at least one basic ring nitrogen and an isocyanate-reactive group; disclosed in JP-A-60-16631, JP-A-2-612, and JP-A-63-241018. A polymer having a main chain composed of polyurethane / polyurea pendant to a group having a plurality of tertiary amino groups or basic cyclic nitrogen atoms; water-soluble poly (disclosed in JP-A-1-279919). (Oxyalkylene) a steric stabilizing unit having a chain, a structural unit and a copolymer comprising an amino group-containing unit, Is amino group-containing monomer units are contained tertiary amino group or a group or a group of the quaternary ammonium acid addition salts thereof, the copolymer 1g per 0.025
Included are copolymers containing .about.0.5 milliequivalent amino groups.

Further, a main chain composed of an addition polymer disclosed in JP-A-6-100642 and at least 1
Of C1 to C4 alkoxy polyethylene or polyethylene-copropylene glycol (meth) acrylate stabilizer units, and 2,500 to 2
An amphipathic copolymer having a weight average molecular weight of 20,000, the main chain comprising up to 30% by weight of non-functional structural units and a total of up to 70% by weight of stabilizer and functional units. And the functional unit is a substituted or unsubstituted styrene-containing unit, a hydroxyl group-containing unit and a carboxyl group-containing unit, and a hydroxyl group and a carboxyl group, a hydroxyl group and a styrene group and a hydroxyl group. The ratio of the group to the propyleneoxy group or the ethyleneoxy group is 1: 0.10 to 2 respectively.
6.1; 1: 0.28-25.0; 1: 0.80-6
An example is an amphipathic polymer of 6.1.

The above-mentioned copolymer (2) has a pigment affinity group of 1
Those which are present in the molecule in an amount of 2 to 3,000 are preferable. Two
If it is less than 300, the dispersion stability is not sufficient, and
If the number exceeds 0, the viscosity becomes too high and handling becomes difficult, and the particle size distribution of the colloidal particles becomes wide, and the saturation decreases. More preferably, it is 25-1,500.

The copolymer (2) preferably has a number average molecular weight of 2,000 to 1,000,000. When it is less than 2,000, the dispersion stability is not sufficient, and when it exceeds 1,000,000, the viscosity becomes too high and the handling becomes difficult, and the particle size distribution of the colloidal particles becomes broad and the saturation decreases. To do. More preferably, 4,000
It is 0 to 500,000.

The linear polymer (3) having a pigment-affinity part consisting of a pigment-affinity group at one end of the main chain is composed of one or a plurality of pigment-affinity groups only at one end of the main chain. It has a pigment affinity portion, but has sufficient affinity for the pigment surface.

The linear polymer (3) is not particularly limited, and for example, one of the basic AB block polymers disclosed in JP-A-46-7294 is basic; US A-B in which an aromatic carboxylic acid is introduced into the A block disclosed in Japanese Patent No. 4,656,226
Block-type polymer; A- whose one end is a basic functional group disclosed in U.S. Pat. No. 4,032,698
B-block type polymer; disclosed in U.S. Pat. No. 4,070,388, A- in which one end is an acidic functional group.
B block type polymer: A- in which an aromatic carboxylic acid is introduced into the A block described in U.S. Pat. No. 4,656,226 disclosed in JP-A-1-204914.
Examples thereof include those having improved weathering yellowing resistance of B block type polymers.

The linear polymer (3) preferably has 2 to 3,000 pigment-affinitive groups in one molecule. When it is less than 2, the dispersion stability is not sufficient,
If it exceeds 3,000, the viscosity will be too high and handling will be difficult, and the particle size distribution of the colloidal particles will be wide,
Saturation decreases. More preferably, it is 5 to 1,500.

The linear polymer (3) preferably has a number average molecular weight of 1,000 to 1,000,000. When it is less than 1,000, the dispersion stability is not sufficient, and when it exceeds 1,000,000, the viscosity is too high, and it becomes difficult to handle, and the particle size distribution of colloidal particles is widened and the saturation is lowered. To do. More preferably 2,0
It is from 00 to 500,000.

As the above-mentioned polymer dispersant, a commercially available one may be used. As the above commercial products,
For example, Sols Perth 20000, Sols Perth 240
00, Sols Perth 26000, Sols Perth 2700
0, Sols Perth 28000 (manufactured by Zeneca); Disperbic 160, Disperbic 161, Disperbic 162, Disperbic 163, Disperbic 166, Disperbic 170, Disperbic 180, Disperbic 182, Disperbic 184, Disperbic 190 ( Manufactured by Big Chemie); EFKA-46, EFKA-47, EFKA-4
8, EFKA-49 (manufactured by EFKA Chemical Co.); polymer 100, polymer 120, polymer 150, polymer 400, polymer 401, polymer 402, polymer 4
03, polymer 450, polymer 451, polymer 45
2, polymer 453 (manufactured by EFKA Chemical Co.); Azisper PB711, Azisper PA111, Azisper P
B811, Addisper PW911 (manufactured by Ajinomoto Co.); Floren DOPA-158, Floren DOPA-22,
Floren DOPA-17, Floren TG-730
W, Floren G-700, Floren TG-720W
(Manufactured by Kyoeisha Chemical Co., Ltd.) and the like.

The above-mentioned polymer dispersant has a graft structure in which a pigment-affinitive group is present in the side chain and has a side chain constituting a solvation part [the above-mentioned comb-shaped polymer (1)]; ,
Since it has a pigment-affinitive group [the above-mentioned copolymer (2) and the above-mentioned linear polymer (3)], the dispersibility of the colloidal particles is good, and it is suitable as a protective colloid for the metal colloidal particles. Is. By using the above-mentioned polymer dispersant, a metal colloidal particle dispersion containing metal colloidal particles at a high concentration can be obtained.

The content of the above-mentioned polymer dispersant is the above-mentioned metal 1
50 to 1,000 parts by weight is preferable with respect to 00 parts by weight. If it is less than 50 parts by weight, the dispersibility of the metal colloidal particles will be insufficient, and if it exceeds 1,000 parts by weight, the amount of the polymer dispersant mixed in the ink will increase.
Problems such as physical properties tend to occur. More preferably 1
It is from 00 to 650 parts by weight.

The metal colloidal solution is a hydrosol when the solvent is water. The concentration of the metal colloidal solution can be 50 mM or more in the case of hydrosol and 10 mM or more in the case of organosol.

In the colloidal solution of the above metal, the average particle size of the colloidal particles is preferably 5 to 30 nm. When it is less than 5 nm, the color density is low, and when it exceeds 30 nm, the saturation is low. In addition, the colloidal particles,
Since the particle size distribution is narrow, it is dark and highly saturated.

The metal colloidal solution used in the ink of the present invention has high saturation and contains metal colloidal particles at a high concentration, and is therefore suitable as a coloring material.
It is possible to obtain a recorded image with bright color and high density. Further, the colloidal solution of the metal in the ink of the present invention has good compatibility with the solvent in the ink and is stable and does not aggregate even when added to such an ink, so that the storage stability of the ink state is also improved. In addition to being very good, even a photo printer that ejects small droplets with an ejection volume of 5 pl or less has excellent ejection characteristics, and it is possible to print an image of so-called photographic quality.

The colloidal solution of metal contained in the ink of the present invention can be obtained by the production method described below. That is, a metal compound is dissolved in a solvent, a polymer dispersant is added, and then the metal compound is reduced.

In the production method of the present invention, the metal compound is used by dissolving it in a solvent. The solvent is not particularly limited as long as it can dissolve the compound containing the metal, and examples thereof include water; organic solvents such as acetone, methanol, ethylene glycol, and ethyl acetate. These may be used alone,
You may use 2 or more types together. When water and an organic solvent are used as a mixture, the organic solvent is preferably water-soluble.

When the solvent is water, the resulting colloidal solution becomes a hydrosol. In this case, the metal compound is preferably dissolved in water so as to have a concentration of 50 mM or more. If it is less than 50 mM, a high-concentration colloidal solution cannot be obtained. More preferably 1
It is at least 00 mM.

When silver is used as the noble metal, the pH of the aqueous solution is preferably 7 or less. When the pH exceeds 7, for example, when silver nitrate is used as a silver compound,
By-products such as silver oxide are generated when silver ions are reduced,
It is not preferable because the solution becomes cloudy. When the pH of the aqueous solution exceeds 7, it is preferable to adjust the pH to 7 or less by adding nitric acid or the like of about 0.1N.

When the above solvent is an organic solvent, the obtained colloidal solution becomes an organosol. In this case, the metal compound is preferably dissolved in the organic solvent so as to have a concentration of 10 mM or more. If it is less than 10 mM, a high-concentration colloidal solution cannot be obtained.
More preferably, it is 50 mM or more.

When the solvent is composed of water and a water-soluble organic solvent, first, the metal compound is dissolved in water, and then the water-soluble organic solvent in which the polymer dispersant is dissolved is added to form a solution. It is preferable. The organosol can be prepared at a higher concentration by dissolving the metal compound in water. At this time, the metal compound is preferably dissolved in water to a concentration of 50 mM or more. If it is less than 50 mM, a high-concentration colloidal solution cannot be obtained. More preferably, it is 100 mM or more.

The blending amount of the above-mentioned polymer dispersant is the above-mentioned metal 1
50 to 1,000 parts by weight is preferable with respect to 00 parts by weight. If it is less than 50 parts by weight, the dispersibility of the metal colloidal particles is insufficient, and if it exceeds 1,000 parts by weight, the amount of the polymer dispersant mixed with the solvent in the ink when the ink is prepared. As a result, the physical properties and the like are likely to become defective. More preferably, it is 100 to 650 parts by weight.

In the method for producing the metal colloidal solution used in the ink of the present invention, the metal ion is reduced after the polymer dispersant is added to the metal compound solution. The method of reduction is not particularly limited, and examples thereof include a method of adding a compound and chemical reduction, a method of irradiating with light using a high pressure mercury lamp, and the like.

The above compound is not particularly limited, and examples thereof include alkali metal borohydride salts such as sodium borohydride which have been conventionally used as a reducing agent; hydrazine compounds; citric acid or its salt, succinic acid or its salt. Etc. can be used. Further, in the present invention, an amine can be used in addition to the above reducing agent.

By using the above amine, it is not necessary to use a highly dangerous and harmful reducing agent, and there is no need to use heating or a special light irradiation device, and the temperature is about 5 to 100 ° C., preferably 20. The metal compound can be reduced at a reaction temperature of about -80 ° C. Therefore, when the above amine is used, the object of the present invention can be extremely advantageously achieved in combination with the use of the above polymer dispersant.

The amine is not particularly limited, and examples thereof include propylamine, butylamine, hexylamine,
Diethylamine, dipropylamine, dimethylethylamine, diethylmethylamine, triethylamine, ethylenediamine, N, N, N ', N'-tetramethylethylenediamine, 1,3-diaminopropane, N, N,
Aliphatic amines such as N ', N'-tetramethyl-1,3-diaminopropane, triethylenetetramine, tetraethylenepentamine; piperidine, N-methylpiperidine, piperazine, N, N'-dimethylpiperazine, pyrrolidine, N Alicyclic amines such as methylpyrrolidine and morpholine; aromatic amines such as aniline, N-methylaniline, N, N-dimethylaniline, toluidine, anisidine and phenetidine; benzylamine, N-methylbenzylamine, N, N- Dimethylbenzylamine, phenethylamine, xylylenediamine, N, N, N ', N'-
Examples thereof include aralkylamines such as tetramethylxylylenediamine. Examples of the amine include methylaminoethanol, dimethylaminoethanol, triethanolamine, ethanolamine, diethanolamine, methyldiethanolamine, propanolamine, 2- (3-aminopropylamino) ethanol, butanolamine, hexanolamine, dimethylamino. Mention may also be made of alkanolamines such as propanol. Of these, alkanolamines are preferred.

The amount of the amine added is preferably 1 to 50 mol per 1 mol of the solution of the metal compound. 1
If it is less than mol, the reduction is not sufficiently carried out and 50mo
When it exceeds 1, the stability against aggregation of the produced colloidal particles decreases. More preferably, it is 2 to 8 mol.

When sodium borohydride is used as the reducing agent, the sodium borohydride is expensive and must be handled with care, but since it can be reduced at room temperature, it cannot be heated or heated. There is no need to prepare a special light irradiation device.

The amount of sodium borohydride added is
1 to 50 mol is preferable to 1 mol of the above-mentioned metal compound. When it is less than 1 mol, reduction is not sufficiently carried out, and when it exceeds 50 mol, stability against aggregation is lowered.
More preferably, it is 1.5 to 10 mol.

When citric acid or a salt thereof is used as the reducing agent, it is possible to reduce precious metal ions, copper ions, etc. by heating under reflux in the presence of alcohol. The citric acid or the salt thereof has an advantage that it is very inexpensive and easily available. It is preferable to use sodium citrate as the citric acid or its salt.

The addition amount of the citric acid or its salt is preferably 1 to 50 mol per 1 mol of the metal compound. If it is less than 1 mol, the reduction is not sufficiently carried out, and 5
If it exceeds 0 mol, the stability against aggregation is reduced. More preferably, it is 1.5 to 10 mol.

According to the method for producing a metal colloidal solution of the present invention, it is possible to obtain a metal colloidal solution having a concentration of 50 mM or more in the case of hydrosol and 10 mM or more in the case of organosol. In addition, the obtained metal colloidal solution has a colloidal particle size of 5 to 30 nm and a narrow particle size distribution, so that it is dark and highly saturated.

The method for producing a metal colloidal solution of the present invention is simply carried out in a small number of steps such as dissolving the above-mentioned metal compound in a solvent to form a solution, adding the above-mentioned polymer dispersant, and then reducing to a metal. And the saturation is high,
It is possible to manufacture a colloidal solution of a metal having a concentration 10 times or more higher than that of a conventional colloidal solution of a noble metal. In particular, by using an alkanolamine, 20 to
It can be easily produced under mild conditions of about 80 ° C. Since the ink of the present invention uses the metal colloid solution as a coloring material, the obtained recorded matter gives a bright chromatic color derived from plasmon absorption when the metal colloid particle concentration is relatively low, When the concentration of colloidal particles of the metal is relatively high, a recorded matter having a gloss peculiar to the metal is obtained. Further, since these recorded materials are chemically stable, they do not easily fade.

In the present invention, in consideration of the scratch resistance of the recorded matter with the ink of the present invention, after the recording with the ink on the recording medium, the polymer dispersant forms a film to form metal fine particles on the recording medium. Polymeric dispersants which can be fixed are particularly suitable. When the ink of the present invention is used for recording on a recording medium that withstands high temperatures, it is also possible to heat the recorded matter to burn off the polymer dispersant and leave only the metal thin film. Further, the ink containing colloidal particles can further improve the recording characteristics of the ink by including an additive such as a rust preventive agent, an antioxidant, an ultraviolet absorber and a stabilizer together with the polymer dispersant. Is.

The preferred solvent used for preparing the ink of the present invention is water or a mixed solvent of water and a water-soluble organic solvent, and particularly preferred is a mixed solvent of water and a water-soluble organic solvent. In addition, the water-soluble organic solvent contains a polyhydric alcohol having an ink drying preventing effect. Further, as the water, it is preferable to use deionized water instead of general water containing various ions.

The content of the above water-soluble organic solvent in the ink according to the present invention is generally 5 to 5% of the total weight of the ink.
70% by mass, preferably 10 to 60% by mass, more preferably 10 to 40% by mass.

The main components of the ink of the present invention are as described above, but various other dispersants, surfactants, viscosity modifiers,
A surface tension adjusting agent, a fluorescent whitening agent and the like can be added as necessary within the range not hindering the achievement of the object of the present invention. For example, cation, anion or nonionic surfactants, polyvinyl alcohol, celluloses,
Examples thereof include viscosity adjusting agents such as water-soluble resins, diethanolamine, triethanolamine, pH adjusting agents such as buffer solutions, and antifungal agents.

In the recording method using the ink of the present invention, the ink jet recording method is effective, and as the recording medium, general plain paper (for example, high-quality paper, medium-quality paper, bond paper) and coated paper are used. It is possible to use any recording medium such as a plastic film for OHP and OHP.

The ink of the present invention is particularly suitable when applied to an ink jet recording method of the type in which the ink is ejected by the bubbling phenomenon of the ink due to thermal energy,
The ejection is extremely stable, and satellite dots are not generated. However, in this case, adjustment of thermal properties (for example, specific gravity, thermal expansion coefficient, thermal conductivity, etc.) may be required.

Furthermore, the ink of the present invention solves the problems of bleeding and the dryness and permeability of recorded matter when recorded on a recording medium, and at the same time, improves the matching with the ink jet recording head. As a physical property, the viscosity at 25 ° C. is 15 cps or less, preferably 10
It is preferable that the surface tension is 20 dyn / cm or more, preferably 25 dyn / cm or more, and the pH is about 4 to 11 at cps or less.

The ink of the present invention prepared from the above components comprises a combination of a suitable liquid medium and the metal fine particles, and therefore has recording characteristics (for example, signal responsiveness, when used for ink jet recording). Stability of droplet formation, ejection stability, long-term continuous recording, etc.), fixability to recording media, or high weather resistance of recorded images (light resistance, gas resistance, moisture resistance, water resistance, etc.), storage It is a well-balanced and excellent product such as stability.

The ink of the present invention is particularly preferably used in an ink jet recording method in which droplets are ejected by the action of heat energy for recording. As a method and apparatus suitable for performing recording using the ink of the present invention, a method and apparatus for applying thermal energy corresponding to a recording signal to the ink in the chamber of the recording head and generating a droplet by this thermal energy Can be mentioned.

The ink jet recording method of the present invention is characterized by using the ink of the present invention. The inkjet recording method of the present invention will be described below with reference to the drawings. First, FIG. 1 and FIG. 2 show an example of a head configuration which is a main part of an inkjet recording apparatus using thermal energy. 1 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 2 is a cross-sectional view taken along the line AB of FIG.

The head 13 is obtained by bonding a glass, ceramic, alumina, silicon or plastic plate or the like having a flow passage (nozzle) 14 for passing ink to the heating element substrate 15. The heating element substrate 15 is made of silicon oxide,
Protective layer 1 made of silicon nitride, silicon carbide, etc.
6, electrodes 17-1 and 17-2 formed of aluminum, gold, aluminum-copper alloy, etc., HfB ₂ , TaN,
Heating resistor layer 1 formed of a high melting point material such as TaAl
8, a heat storage layer 19 made of thermally oxidized silicon, alumina (aluminum oxide) or the like, and a substrate 20 made of a material having a good heat dissipation property such as silicon, aluminum or aluminum nitride. In the present invention, for example, when the flow path (nozzle) 14 for passing the ink and the heat storage layer 19 are made of alumina (aluminum oxide) which is excellent in robustness and corrosion resistance, the electrode 17 and the substrate 20 have thermal conductivity. And when it is made of metallic aluminum having excellent electrical conductivity, a particularly remarkable effect is obtained.

Electrodes 17-1 and 17- of the head 13
When a pulsed electric signal is applied to 2, the area indicated by n on the heating element substrate 15 rapidly generates heat, bubbles are generated in the ink 21 in contact with this surface, and the meniscus 23 is projected by the pressure. , The ink 21 is ejected through the nozzle 14 of the head, and the ink droplet 24 is ejected from the ejection orifice 22.
And fly toward the recording medium 25. In Figure 3,
FIG. 2 is an external view of an example of a multi-head in which a large number of heads shown in FIG. 1 are arranged. This multi-head has a multi-nozzle 26
It is made by bonding a glass plate 27 having a heating element and a heating head 28 similar to that described in FIG.

FIG. 4 shows an example of an ink jet recording apparatus incorporating this head. In FIG. 4, reference numeral 61 denotes a blade as a wiping member, one end of which is held and fixed by a blade holding member, and has a form of a cantilever. The blade 61 is arranged at a position adjacent to the recording area of the recording head 65, and in the case of this example, is held in a form protruding in the movement path of the recording head 65.

Reference numeral 62 denotes a cap on the projecting opening surface of the recording head 65, which is arranged at the home position adjacent to the blade 61, moves in a direction perpendicular to the moving direction of the recording head 65, and contacts the ink ejection opening surface. It is provided with a structure for contacting and capping. Further, 63 is an ink absorber provided adjacent to the blade 61, and like the blade 61, is held in a form protruding in the moving path of the recording head 65. The blade 61, the cap 62, and the ink absorber 63 constitute an ejection recovery unit 64, and the blade 61 and the ink absorber 63 remove water and dust on the ejection port surface.

Reference numeral 65 denotes a discharge energy generating means,
A recording head 66 for performing recording by ejecting ink onto a recording medium facing the ejection port surface provided with the ejection port, 66 is the recording head 6
5 is a carriage for carrying the recording head 65 and moving the recording head 65. The carriage 66 slidably engages with the guide shaft 67, and a part of the carriage 66 is connected (not shown) to a belt 69 driven by a motor 68. As a result, the carriage 66 can move along the guide shaft 67, and the recording area of the recording head 65 and its adjacent area can move.

Reference numeral 51 is a paper feeding section for inserting a recording medium, and 52 is a paper feeding roller driven by a motor (not shown). With these configurations, the recording medium is fed to the position facing the ejection port surface of the recording head 65, and is ejected to the ejection unit provided with the ejection roller 53 as the recording progresses. With the above configuration, when the recording head 65 finishes recording and returns to the home position, the cap 62 of the ejection recovery unit 64 is retracted from the movement path of the recording head 65, but the blade 61 is projected in the movement path. . As a result, the ejection port of the recording head 65 is wiped.

When the cap 62 comes into contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to project into the movement path of the recording head. When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same positions as the positions at the time of wiping described above. As a result, the ejection opening surface of the recording head 65 is wiped even during this movement. The above-mentioned movement of the recording head to the home position is performed not only at the end of recording and at the time of ejection recovery, but also at a predetermined interval while the recording head moves in the recording area to the home position adjacent to the recording area. Then
The wiping is performed along with this movement.

FIG. 5 is a diagram showing an example of an ink cartridge in which ink is supplied to the recording head via an ink supply member, for example, a tube. 40 here
Is an ink containing portion containing the supply ink, for example, an ink bag, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into this stopper 42, the ink in the ink bag 40 can be supplied to the head. Reference numeral 44 is an ink absorber that receives waste ink.
As the ink container, it is preferable that the surface in contact with the ink is made of polyolefin, especially polyethylene.

The ink jet recording apparatus used in the present invention is not limited to the one in which the recording head and the ink cartridge are separate from each other as described above, and the one in which they are integrated as shown in FIG. 6 is also preferable. Is. In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink containing portion that contains ink, for example, an ink absorbing body is stored, and the ink in the ink absorbing body has a head portion 71 having a plurality of orifices. It is configured to be ejected as an ink droplet from. As a material for the ink absorber, it is preferable to use polyurethane, polyolefin fiber or the like. Further, the structure may be such that the ink containing portion is an ink bag having a spring or the like prepared therein, without using the ink absorber. Reference numeral 72 is an atmosphere communication port for communicating the inside of the cartridge with the atmosphere. The recording unit 70 is used in place of the recording head 65 shown in FIG. 4, and is detachable from the carriage 66.

[0078]

EXAMPLES Next, the present invention will be described more specifically by way of examples, comparative examples and use examples. In the text, "part" and "%" are based on mass unless otherwise specified.
After thoroughly mixing and dissolving the respective components shown in Table 1 below, pressure filtration was performed with a 0.2 μm filter to prepare an ink. The gold colloid and the silver colloid in Table 1 are described in JP-A-11-8064.
The colloidal solution prepared according to the method described in Japanese Patent No. 7 etc. was used.

[0079]

[0080]

Example of use Ink jet printer BJ-F870 using the ink obtained as described above and using a heating element as an ink ejection energy source in an ink jet recording apparatus.
(Product name: manufactured by Canon) was used to print a solid image with a duty varied from 0 to 100% on PR-101 (product name: manufactured by Canon) to obtain a recorded product. In each case, a clear solid image was obtained. Regarding the tint of a 100% duty solid image, gold was obtained in Example 1, silver was obtained in Example 2, magenta was obtained in Example 3, and yellow was obtained in Example 4.

(Evaluation of Lightfastness) O.V. of recorded matter obtained by printing D. The light resistance was evaluated using a solid image of 1.0. (Test conditions) A light resistance exposure test was performed using a xenon fade meter according to the following test conditions.・ Irradiation light amount: 70 klux ・ Test time: 100 hours ・ Temperature and humidity conditions in test tank: 24 ° C ・ 60% RH ・ Filter: (outer) soda lime, (inner)
Borosilicate

(Evaluation conditions) The color of the solid image portion before exposure and the image density after exposure are measured by Gretag Spectrolino (Gretag Mac
The light resistance was evaluated based on the concentration residual rate data after the light resistance exposure test with reference to the standard of ISO10977 (1993) and the following criteria. ◯: The residual density ratio is 90% or more. Δ: The residual concentration ratio is 80% to 89%. X: The residual density is less than 80%.

[0084]

[0085]

INDUSTRIAL APPLICABILITY In the recorded image using the ink of the present invention, particularly the recorded image using the ink jet recording method, it is possible to obtain a recorded matter having a metallic luster having high weather fastness which has never been obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a head of an inkjet recording apparatus.

FIG. 2 is a sectional view taken along the line AB of FIG.

FIG. 3 is a schematic explanatory diagram of a multi-head.

FIG. 4 is a schematic perspective view showing an embodiment of an inkjet recording apparatus.

FIG. 5 is a vertical sectional view showing an embodiment of an ink cartridge.

FIG. 6 is a perspective view showing an example of a recording unit.

[Explanation of symbols]

13: Head 14: flow path (nozzle) 15: Heating element substrate 16: Protective layer 17-1, 17-2: Electrodes 18: Heating resistor layer 19: Heat storage layer 20: substrate 21: Ink 22: Discharge orifice 23: Meniscus 24: Ink droplet 25: Recording medium 26: Multi nozzle 27: Glass plate 28: Heating head 40: Ink bag 42: Stopper 44: Ink absorber 45: Ink cartridge 51: Paper feeding department 52: Paper feed roller 53: Paper ejection roller 61: Blade 62: Cap 63: Ink absorber 64: Discharge recovery unit 65: recording head 66: Carriage 67: Guide shaft 68: Motor 69: Belt 70: Recording unit 71: Head part 72: Air communication port

Continued front page    F-term (reference) 2C056 EA13 FC02                 2H086 BA55 BA59                 4J039 AE05 AE07 AE09 BA06 BC19                       BC32 BC33 BC54 BC58 BE22                       EA34 FA01 FA03 FA04 FA05                       FA06 GA24

Claims (12)

[Claims] 1. An ink containing metal fine particles dispersed in a liquid medium as a coloring material. 2. The ink according to claim 1, wherein the fine metal particles are metal colloidal particles. 3. The ink according to claim 1, wherein the metal of the metal fine particles is a noble metal or copper. 4. The ink according to claim 1, wherein the noble metal is at least one selected from the group consisting of gold, silver and platinum. 5. The ink according to claim 1, which contains a polymer dispersant as a dispersant for the metal fine particles. 6. A solution obtained by dissolving the metal compound in a solvent containing a polymer dispersant, or by dissolving the metal compound in a solvent and then adding the polymer dispersant to the solution. The ink according to claim 5, wherein the ink is metal colloidal particles produced by reducing the metal compound to a metal. 7. The polymer dispersant comprises the following (i) to (ii):
The ink according to claim 5, which has the structure of any one of i). (I) a polymer having a comb-like structure having a pigment affinity group in at least one of the main chain and a plurality of side chains and having a plurality of side chains forming a solvation portion, (ii) a pigment in the main chain A polymer having a plurality of pigment-affinity moieties composed of an affinity group, (iii)
A linear polymer having a pigment-affinity portion composed of a pigment-affinity group at one end of the main chain. 8. The polymer of (i) has 2 to 3,000 pigment-affinity groups in one molecule, and has 2 to 1,000 side chains constituting a solvation portion in one molecule. And the number average molecular weight is 2,000 to 1,000,000, and the polymer (ii) has 2 to 2 pigment-affinitive groups in one molecule.
It has 3,000 and has a number average molecular weight of 2,000 to 1,0.
The polymer of (iii) has 2 to 3,000 pigment affinity groups in one molecule, and the number average molecular weight is 1,000 to 1,000,000. The ink according to item 7. 9. The metal colloid comprises a metal compound,
The ink according to claim 2, which is obtained by dissolving in a solvent, adding a polymer dispersant, and then reducing the polymer dispersant. 10. The ink according to claim 1, wherein the liquid medium is water or a mixture of water and a water-soluble organic solvent. 11. The ink according to claim 1, which is for ink jet recording. 12. An ink jet recording method comprising a step of ejecting the ink according to claim 11 from an orifice according to a recording signal.