JP2003306625A - Ink composition and method for printing using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition forming a printed surface having a good metallic luster without causing separation and settling of metal particles and clogging of a head when printing is carried out by an ink jet method and to provide a method for printing in order to form the printed surface having a high specular glossiness and the good metallic luster using the ink composition. <P>SOLUTION: The ink composition comprises a metallic colloid in a dispersion medium. The method for printing comprises printing the surface of a porous material which is to be printed and has ≥200 s Oken type smoothness or ≥20 degrees of 60° specular surface glossiness specified by JIS Z8471<SB>-1997</SB>or a nonporous material which is to be printed and has ≤35° contact angle with the ink composition measured according to a static drop method specified by JIS R3257<SB>-1999</SB>with the ink composition. <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 a novel ink composition capable of forming a printed surface having a metallic luster by, for example, printing by an ink jet system, and a specular gloss using the ink composition. The present invention relates to a printing method for forming a printing surface having a high degree of metallic luster.

[0002]

2. Description of the Related Art In recent years, so-called inkjet printing has been used in a wide range of fields from output printing of personal computers to printing of large-sized printed matter such as commercial advertisements. In inkjet printing,
An ink composition having three light-transmissive three primary colors of cyan, magenta, and yellow, or a multicolor of four or more colors based on these three colors, on a printing medium such as paper Is used to print an ink pattern, and a full-color image or the like is expressed by mixing colors.

However, due to the above expression method, there is a problem in that metallic gloss cannot be expressed in ink jet printing. Therefore, recently, various ink compositions using fine metal particles as a colorant have been proposed in order to express metallic luster. For example, Japanese Patent Laid-Open No. 11-323223
In the publication, a metal vapor deposition film laminated on a resin film,
There is disclosed an ink composition in which a resin film is stretched and finely pulverized to produce flake-shaped metal particles, which are dispersed in a dispersion medium as a colorant.

In Japanese Patent Laid-Open No. 11-343436, particles having a multilayer structure produced by pulverizing a laminate of two or more layers of a metal vapor deposition film and a resin layer by the same method are replaced with the above metal particles. Then, an ink composition dispersed in a dispersion medium as a colorant is disclosed. Further, Japanese Patent Laid-Open No. 2000-1720
Japanese Unexamined Patent Publication No. 8 discloses an ink composition in which the metal particles are encapsulated in microcapsules and dispersed as a colorant.

[0005]

However, the flake-shaped metal particles used in the first ink composition have a thickness of about 0.08 to 0.12 μm and a maximum length of 0.8 to It is as large as about 2 μm, and is flat and irregular as seen from the above manufacturing method, and the shape and size are not uniform among the particles. Further, the particles of the multilayer structure used in the second ink composition have a larger thickness of about 0.75 to 1.1 μm and a maximum length of about 3.8 to 4.0 μm at the level of Examples, and have a flat shape. , And the shape and size of each particle are not uniform.

The microcapsules used in the third ink composition are larger particles having a diameter of about 5 to 70 μm. Therefore, all of these particles, which are often used in ink compositions for inkjet, have insufficient dispersion stability in an aqueous dispersion medium such as water or a water-soluble organic solvent, and are actually used after being manufactured. Separation until used by end users,
This may cause problems such as sedimentation and unusability.

Further, in recent years, high quality image printing by the ink jet method has been rapidly progressing, and in order to improve the image quality, it is necessary to make the droplets of the ink composition ejected from the printer head as small as possible. Therefore, the head diameter tends to be reduced. However, the above-mentioned large particles, which are flat and irregular, and whose shape and size are not uniform among the particles, cannot sufficiently deal with such miniaturization, and the head is likely to be clogged. There are also problems.

Furthermore, even when printing is performed using the conventional ink composition containing large particles as described above, the graininess of the individual particles is conspicuous on the printed surface, and for example, metal lumps or metal foils are used. It is difficult to express a smooth, good metallic luster, like the surface of a continuous metallic film. An object of the present invention is to form a printing surface having a good metallic luster without causing separation of metal particles, sedimentation, or clogging of a head when printing by an inkjet method. It is to provide a novel ink composition.

Another object of the present invention is to provide a novel printing method using the above ink composition to form a printing surface having a high specular gloss and a good metallic luster. It is in.

[0010]

Means for Solving the Problem and Effect of the Invention The invention according to claim 1 is an ink composition characterized in that a dispersion medium contains a metal colloid. For example, an aqueous metal colloid using water as a dispersion medium is a mixture of an aqueous solution containing metal ions and a reducing agent, or JP-A-7-735.
As described in JP-A No. 11-115, an aqueous solution containing metal ions is sprayed and brought into contact with a hydrogen flame to reduce and precipitate a metal in the aqueous solution for production.

The metal particles contained in the metal colloid have uniform particle diameters because the above-mentioned reduction reaction proceeds uniformly in the system, and the particle size distribution is sharp. The metal particles of many metal colloids are almost spherical in shape. Moreover, by adjusting the reaction conditions, the particle size of the metal particles can be made smaller than the conventional one. Further, the metal particles are deposited and generated by a reduction reaction in water as described above, and the surface thereof has hydrophilicity, so that the dispersion stability in an aqueous dispersion medium is also excellent.

Therefore, according to the ink composition of the first aspect, printing having a metallic luster can be achieved without causing separation or sedimentation of metal particles, or clogging of the head during printing by an inkjet method. A surface can be formed. In addition, it is possible to form a smooth printing surface with a graininess that is not conspicuous and that has an unprecedentedly good metallic luster. The addition amount of the metal colloid is preferably 1 to 20% by weight in terms of the content ratio of the metal particles in the metal colloid with respect to the total amount of the ink composition.

Therefore, the invention according to claim 2 is the ink composition according to claim 1, wherein the content ratio of the metal particles in the metal colloid is 1 to 20% by weight based on the total amount of the ink composition. Further, the composition of the above ink composition can be applied to various inks such as those for markers and ballpoint pens, but in particular, as described above, clogging of the head during printing by the inkjet method. It is less likely to occur, and therefore, it is preferably applied to ink for printing by an inkjet method.

Therefore, the invention according to claim 3 is the ink composition according to claim 1, which is for printing by an ink jet system. The inventors, using the above ink composition, for example, the equivalent such as the surface of the metal foil, 20 degree specular gloss defined in Japanese Industrial Standard JIS Z8471 _-1997 is that more than 75 degrees, high specular gloss It was considered to form a printed surface having a smooth metallic luster.

As a result, when printing on a porous printing medium represented by paper, it has been found that the specular glossiness of the printing surface can be improved by using the printing medium having the highest surface smoothness. Obtained. That is, the porous substrate is
Since the ink composition is absorbed when printing, the surface condition of the printing medium is directly reflected on the surface condition of the printing surface. For this reason, when the surface of the printing medium has low smoothness, the surface smoothness of the printed surface also becomes low, and diffuse reflection occurs, which tends to impair the metallic luster. On the other hand, the higher the surface smoothness of the material to be printed, the higher the surface smoothness of the printed surface,
Diffuse reflection is less likely to occur and metallic luster is improved.

Therefore, the inventor of the present invention uses the above ink composition to form a porous surface for forming a printing surface having a smooth metallic luster with a high specular gloss of 20 degrees or more as described above. As a result of further studying what range of surface smoothness should be used as the printing medium, the Oken type smoothness, which is a standard for defining the surface smoothness of paper, is 200 seconds or more. 60 is either or defined above JIS _{Z8471 -1997} in
It has been found that a printing object having a specular gloss of 20 degrees or more may be used.

That is, the invention of claim 4 is the same as claim 1
The ink composition according to any one of 1 to 3 has an Oken type smoothness of 200 seconds or more, or JIS Z8471.
_{By -1997} 60 degree specular gloss as defined is printed on the surface of the printing material porous is more than 20 degrees, the JIS _{Z8471 -1997} 20 degree specular gloss as defined is not less than 75 degrees Printing A printing method characterized by forming a surface. The inventor also studied the case of printing on a non-porous printing medium such as a resin film.

As a result, it was found that the wettability of the ink composition is an important factor for improving the specular gloss of the printed surface in the case of a non-porous printing medium. That is, since the non-porous printing material does not absorb the ink composition, when printing is performed, a film of the ink composition is formed on the surface of the printing material. The surface condition of this film, that is, the surface condition of the printing surface. Therefore, when the wettability between the ink composition and the surface of the printing medium is low, the ink composition cannot be repelled on the surface of the printing medium at the time of printing to form a uniform film, which causes irregular reflection, The metallic luster tends to be impaired. On the other hand, the higher the wettability between the ink composition and the surface of the material to be printed, the more improved the uniformity of the film. As a result, the surface smoothness of the printed surface also becomes higher, and diffuse reflection is less likely to occur. Is improved.

Therefore, the inventor of the present invention uses the above ink composition to form a printing surface having a smooth metallic luster having a high specular gloss of 20 degrees or more, which is 75 degrees or more. objects and further studies result whether wettability may be any degree in the range above the non-porous printing surface of, JIS R3257 _{-199 9}
It was found that the contact angle measured by dropping the ink composition on the surface of the printing medium according to the sessile drop method defined in paragraph 3 is not more than 35 degrees.

That is, the invention of claim 5 is the same as claim 1.
JIS of the ink composition according to any one of 1 to 3
R3257 nonporous surface of the printing material of the contact angle measured according to the sessile drop method as defined is less than 35 degrees _-1999, by printing using the above ink composition, J
IS Z8471 _-1997 20 degree specular gloss as defined is the print method characterized by forming the printing surface is at least 75 degrees.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION [Ink Composition] The ink composition of the present invention is characterized by containing a metal colloid in the dispersion medium as described above. <Metal colloid> As the metal colloid, for example, gold, silver,
Fine metal particles made of various metals such as ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, aluminum, zinc, tin, nickel, cobalt and iron are colloidal in an aqueous dispersion medium such as water or alcohol. Those dispersed in can be used.

The average particle diameter of the metal particles is not particularly limited, 1 × ¹⁰ -3 is preferably from ^{~5 × 10 -1 μm, 1 ×} 10 -3 ~8 × 10 -2 and even more at [mu] m preferable. If the average particle size of the metal particles is less than the above range, it is difficult to manufacture. On the other hand, when the average particle diameter of the metal particles exceeds the above range, the granular feeling of the individual metal particles becomes conspicuous, which may make it impossible to form a printed surface having a smooth metallic luster. Further, the metal particles may not be uniformly dispersed in the dispersion medium that constitutes the ink composition with good dispersion stability, or clogging of the head may not be prevented.

The aqueous metal colloid is produced by reducing an aqueous solution containing metal ions as described above to precipitate metal particles in the aqueous solution. For example, an aqueous gold colloid is generally produced by reducing an aqueous solution of chloroauric acid. First, an aqueous solution of chloroauric acid is neutralized with an aqueous solution of potassium hydroxide, and then an aqueous solution of potassium thiocyanate is added to this solution to gradually raise the temperature. Then, when left at 80 ° C. for about 2 hours, the liquid becomes cloudy yellowish brown due to the precipitated gold particles, but when left at room temperature for several days, the gold particles completely precipitate.

Then, next, the operation of substituting the supernatant with distilled water and stirring the mixture is repeated about 3 times, whereby an aqueous gold colloid having good dispersion stability of gold particles can be produced. The water-based silver colloid is produced, for example, by reducing an aqueous solution of silver nitrate. That is, when a silver nitrate aqueous solution is added to a mixed solution of an iron (II) sulfate aqueous solution and a citric acid aqueous solution, a dark blue precipitate is obtained. Then, this precipitate is separated by filtration, washed with distilled water, and then poured with distilled water to produce a red-colored aqueous silver colloid having good dispersion stability of silver particles.

All the colloids of various metals including gold and silver described above are described in JP-A-7-173511.
In the publication, spraying an aqueous solution containing metal ions,
It can also be produced by a method of reducing and precipitating by contacting with a hydrogen flame. When a metal colloid is produced by these production methods, the dispersion stability of the metal particles can be further improved by adding a surfactant or the like to the aqueous solution at any time before or after the reduction reaction.

The metal colloid having a water-soluble organic solvent such as alcohol as a dispersion medium is prepared by separating metal particles from the water-based metal colloid produced by the above-mentioned production method and dispersing them in the water-soluble organic solvent. It can be manufactured by a method. Furthermore, as described later, when a water-insoluble organic solvent such as toluene is contained in the ink composition as a dispersion medium, a metal colloid similarly containing a water-insoluble organic solvent as a dispersion medium can be used. Among such metal colloids, for example, toluene-based gold colloid is manufactured by the following procedure.

First, a solution prepared by dissolving a polymer pigment dispersant in toluene is added to an aqueous chloroauric acid solution, and the mixture is stirred and mixed. Next, diethylaminoethanol as a reducing agent was added to the sufficiently mixed liquid, and the mixture was further stirred at room temperature for about 1 hour and then allowed to stand to give a colorless transparent aqueous phase,
The gold particles are reduced and precipitated, and separated into a dark red-colored toluene phase. Therefore, by extracting only the toluene phase and then washing with water, a bright red toluene-based gold colloid can be obtained.

The amount of the metal colloid added to the ink composition is adjusted so that the content of the metal particles contained in the metal colloid with respect to the total amount of the ink composition is 1 to 20% by weight. It is more preferably adjusted to 3 to 15% by weight. When the content ratio of the metal particles is less than the above range, the metal particles are insufficient,
It may not be possible to form a printed surface with good metallic luster.

On the contrary, when the content ratio of the metal particles exceeds the above range, the solid content concentration in the ink composition becomes too high. Therefore, when the ink composition is used for ink jet printing, the ink is ejected. There is a possibility that stability may be deteriorated and good printing may not be performed. <Dispersion medium> As the dispersion medium constituting the ink composition, since the metal particles in the metal colloid have hydrophilicity as described above, it is preferable to use an aqueous dispersion medium such as water or a water-soluble organic solvent. .

For example, in the case of an ink composition used for ink-jet printing, water is generally the main component as an aqueous dispersion medium, and if necessary, for example, the drying property of the ink and the permeability to a porous printing medium are provided. It is preferable to use the one to which a water-soluble organic solvent is added in order to adjust the wettability with respect to the non-printed material. In addition, for example, in the case of printing on a non-porous printed material such as plastic, glass, or metal, in order to further improve the wettability with respect to these printed materials, water is used as a dispersion medium without using water. You may use only 1 type, or 2 or more types of organic solvents.

Examples of the water-soluble organic solvent include monohydric alcohols such as methanol, ethanol, 1-propanol, isopropanol, s-butanol and t-butanol; ethylene glycol ether such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether. Examples thereof include dihydric and trihydric alcohols such as propylene glycol, diethylene glycol and glycerin; dimethyl sulfoxide, N-methyl-2-pyrrolidone and methyl ethyl ketone.

Similarly, various non-water-soluble organic solvents can be used as a dispersion medium in order to further improve the wettability of non-porous materials such as plastics, glass and metals. Examples of the water-insoluble organic solvent include aromatic hydrocarbons such as benzene, toluene and xylene, n-paraffin hydrocarbons, and iso-paraffin hydrocarbons.

In addition to the above-mentioned components, the ink composition of the present invention may contain a binder resin, a dispersant, and other various conventionally known components. <Binder resin> The binder resin is for fixing the metal particles to the surface of the material to be printed, and in the aqueous ink composition, for example, cellulose resin, polyamide resin, polyvinylpyrrolidone, water-soluble acrylic resin, etc. It is preferable to use a water-soluble binder resin.

In consideration of improving the water resistance of printing with an aqueous ink composition, the binder resin is:
It is also possible to use a resin which is essentially insoluble in water and soluble in an alkaline aqueous solution in which a basic substance is dissolved. Such a binder resin has, for example, a carboxyl group in the molecule and is insoluble in water as it is, but when added to an alkaline aqueous solution in which a basic substance such as ammonia, an organic amine, and caustic is dissolved, It is possible to use a resin in which the carboxyl group portion reacts with a basic substance to form a water-soluble salt and dissolve it.

Specific examples of preferable binder resins include polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid. Acrylic resins such as alkyl ester copolymers; styrene-acrylic acid copolymers, styrene-
Methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid alkyl ester copolymer, etc. Of the styrene-acrylic acid resin; maleic acid resin, fumaric acid resin, styrene-maleic acid copolymer resin, styrene-maleic anhydride copolymer resin, etc., the molecular weight, acid value, etc. were adjusted to have the above characteristics. One or more resins, particularly high acid value resins, may be mentioned.

Further, in a system which does not use water and uses one or more water-soluble or water-insoluble organic solvents as a dispersion medium, the binder resin is not limited to water-soluble ones, and organic solvents can be used. Various binder resins that are soluble in water can be used. The binder resin preferably has a weight average molecular weight Mw of 10,000 or more in consideration of improving the fixability of printing. However, if the molecular weight is too large, the binder resin is likely to cause precipitation or precipitation, which may result in unstable ejection of the ink composition. In addition, when the ink composition is stored, precipitation or precipitation may easily occur. Therefore, the weight average molecular weight Mw of the binder resin is
Even within the above range, it is particularly preferably 50,000 or less, and considering these characteristics together, 20,000 to 4
More preferably, it is about 10,000.

The content ratio of the binder resin is preferably 0.1 to 3.0% by weight based on the total amount of the ink composition,
It is more preferably 0.5 to 2.0% by weight. If the content ratio is less than this range, the effect of improving the fixing property of printing may be insufficient. Further, if it exceeds this range, the solid content concentration in the ink composition becomes too high, so that the ejection stability of the ink may be deteriorated and good printing may not be performed especially when used in inkjet printing. There is.

<Basic substance> In a water-based ink composition, when a binder resin which is essentially unnecessary for water as described above and is soluble in an alkaline aqueous solution is used, the ink composition is Add basic material. The basic substance has a function of making the ink composition alkaline and dissolving the binder resin described above, and in addition, in order to prevent the corrosion of the head of the inkjet printer and to maintain the dispersion stability of the metal particles. Also works.

As the basic substance, ammonia,
Organic amine, caustic alkali and the like are preferable. Of these, examples of organic amines include monoethanolamine, diethanolamine, triethanolamine, ethylmonoethanolamine, ethyldiethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, mono-1-propanolamine and derivatives thereof. 1 type (s) or 2 or more types can be mentioned.

The amount of the basic substance added is appropriately determined depending on the acid value indicating the free fatty acid content of the binder resin, the pH of the ink composition without the basic substance, and the like.
Although it can be adjusted, it is generally 0.5 to 2 parts by weight per 1 part by weight of the binder resin, and preferably 0.75 to 1.5.
More preferably, it is part by weight. If the addition amount is less than this range, the binder resin cannot be sufficiently dissolved, and thus a uniform ink composition may not be obtained. Further, if it exceeds this range, the pH of the ink becomes too high, which may cause a safety problem or corrode the head of an inkjet printer.

<Dispersant> The dispersant is added when it is desired to further improve the dispersion stability of the metal particles. As a dispersant,
Conventionally known dispersants such as polymer dispersants and surfactants can be used. As the polymer dispersant, natural polymer compounds such as glue, gelatin, casein, albumin and other proteins; gum arabic, tragacanth and other natural gums; saponin and other glucosides; alginic acid and alginate propylene glycol ester, alginate triethanol Alginic acid derivatives such as amines and ammonium alginate; methyl cellulose,
One or more kinds of cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose and the like can be mentioned.

A synthetic polymer compound can also be used as the polymer dispersant. Examples of the synthetic polymer compound include polyvinyl alcohols; polyvinylpyrrolidones; polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid- Acrylic resin such as acrylic acid alkyl ester copolymer; styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-
Acrylic acid alkyl ester copolymer, styrene-α-
Methylstyrene-acrylic acid copolymer, styrene-α-
Styrene-acrylic acid resins such as methylstyrene-acrylic acid-alkyl acrylate copolymers; styrene-maleic acid; styrene-maleic anhydride; vinylnaphthalene-acrylic acid copolymers; vinylnaphthalene-maleic acid copolymers; Vinyl acetate such as vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl-ethylene copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic acid copolymer One or more kinds of the system copolymers and salts thereof may be mentioned.

Among these, a copolymer of a monomer having a hydrophobic group and a monomer having a hydrophilic group, and a polymer composed of a monomer having both a hydrophobic group and a hydrophilic group are particularly preferable as the dispersant. . As the salt, a salt of the above synthetic polymer compound with diethylamine, ammonia, ethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, triethanolamine, diethanolamine, aminomethylpropanol, morpholine, etc. Can be mentioned.

The weight average molecular weight Mw of the synthetic polymer compound is preferably 3,000 to 30,000, and the weight average molecular weight Mw is 5,0.
More preferably, it is from 0 to 15,000. Examples of the surfactant include fatty acid salts, higher alkyl dicarboxylic acid salts, higher alcohol sulfate ester salts, higher alkyl sulfonates, condensates of higher fatty acids and amino acids, sulfosuccinate ester salts, naphthenates, liquid fatty oils. Anionic surfactants such as sulfate ester salts and alkylallyl sulfonates; cationic surfactants such as fatty acid amine salts, quaternary ammonium salts, sulfonium salts and phosphoniums; polyoxyethylene alkyl ethers and polyoxyethylene alkyl esters Examples thereof include one or more nonionic surfactants such as compounds, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, and the like.

The amount of the dispersant added is preferably 0.06 to 3 parts by weight, preferably 0.125 to 1 part by weight of the pigment.
It is more preferably 3 parts by weight. <Other Additives> Examples of other additives include a surface tension adjusting agent, a wetting agent, a fungicide, and a biocide. A nonionic surfactant is mainly used as the surface tension adjusting agent. The surface tension adjusting agent should be added as little as possible in order to prevent bubbling of the ink composition and bleeding of printing, and specifically, the content ratio to the total amount of the ink composition is 0.1% by weight. % Or less, especially 0.
It is preferably not more than 05% by weight, and it is desirable not to add it if possible.

In order to adjust the wettability of the water-based ink composition with respect to the non-porous material to be printed, for example, a surface tension adjusting agent such as a fluorine type surfactant or a silicone type surfactant is added. Good. The wetting agent is added in order to suppress the ink from drying and to prevent the ink from being clogged in the printer head. For example, a divalent or trivalent alcohol, 2-pyrrolidone or a derivative thereof. Are preferred.

Examples of the dihydric alcohol include 1,5
-Pentanediol, propylene glycol, diethylene glycol, etc. can be mentioned, and examples of the trihydric alcohol include glycerin, trimethylolpropane, etc. Furthermore, examples of 2-pyrrolidone and derivatives thereof include 2-pyrrolidone and N-methyl-2-pyrrolidone. The wetting agent may be used alone or in combination of two or more.

The content of the wetting agent is preferably 2 to 30% by weight based on the total amount of the ink composition. When two or more wetting agents are used in combination, the total amount is within the above range. Also, with metal particles of metal colloid origin,
As the colorant, various dyes and pigments can be used together. In this case, for example, it is possible to reproduce the luster of gold without using gold, and to express metallic luster of various colors that are not actually present. Further, a coloring agent such as a dye may be the main component, and the amount of metal particles originating from the metal colloid may be smaller than that. In this case, the metallic luster that reproduces the surface of the metal foil or the like cannot be obtained, but it is possible to reproduce the so-called metallic coating state.

The ink composition of the present invention is produced by blending the above-mentioned components in a predetermined content ratio. The manufactured ink composition can be suitably used particularly for inkjet printing. As a printer adopting an inkjet system, a so-called on-demand type inkjet printer such as a thermal inkjet system or a piezo system, or a so-called continuous type printer that forms ink droplets while circulating ink and prints An inkjet printer or the like can be given.

The ink composition of the present invention can also be used as various inks for, for example, markers and ballpoint pens. [Printing Method (1)] The first printing method of the present invention is
Using the ink composition of the present invention described above, JIS Z8471 is applied to the surface of a porous printing medium such as paper.
It is a method for forming a printing surface having a smooth metallic luster, which has a 20-degree specular gloss of 75 degrees or more specified in _-1997 .

As a specific printing method, any of various printing methods in which the ink composition of the present invention can be used, and an inkjet printing method is particularly preferable. As the porous substrate, as described above, a porous ink-receiving layer having a function of absorbing and fixing the ink composition is laminated on at least one surface of paper or a substrate such as paper or film. Examples include so-called special papers and films for inkjet printers.

[0052] In the first printing process, as a printing substrate of such porous, as described above, Oken type smoothness of 200 seconds or more, or JIS _{Z8471 -1997}
It is necessary to use a material having a 60-degree specular gloss of 20 degrees or more and excellent surface smoothness. The porous printing medium most preferably satisfies both of these two conditions, but may satisfy at least one of them.

In view of forming a printing surface having a smooth metallic luster, the Oken type smoothness of the material to be printed is preferably 600 seconds or more even within the above range, More preferably, it is 2000 seconds or more. For the same reason, the 60-degree specular gloss is preferably 30 degrees or more, and more preferably 100 degrees or more. Of these, the Oken smoothness is a unit that serves as an index for defining the surface smoothness of a sample such as paper.
For details, refer to “Beck's smoothness” [Yamamoto, Kaita,
Iwasaki, Paper and Paper Cooperative Magazine Vol. 20, No. 2 (No. 179), Paper and Pulp Technology Association, published in February, 1966] Smoothness measured using a pressure drop type smoothness measuring instrument. Indicates the degree. The higher the smoothness of the sample surface, the higher the value, and the lower the smoothness, the lower the value.

[Printing Method (No. 2)] The second printing method of the present invention uses the ink composition of the present invention described above, and JIS Z847 is printed on the surface of a non-porous substrate.
It is a method for forming a printing surface having a smooth metallic luster, which has a 20-degree specular gloss of 75 degrees or more specified in _1-1997 . As a specific printing method, any of various printing methods in which the ink composition of the present invention can be used, and an inkjet printing method is particularly preferable.

Examples of the non-porous material to be printed include polyester resin such as PET, plastic such as acrylic resin, polycarbonate resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, or glass or metal. . In the second printing method, JIS R3257 is used as an index of the wettability of the ink composition with respect to the surface of the non-porous printing medium.
_It is necessary to select the combination of the material to be printed and the ink composition so that the contact angle measured according to the static drop method defined in _-1999 is 35 degrees or less.

As specific methods therefor, (1) the material forming the printing medium is selected, (2) the surface of the printing medium is treated by corona discharge, etc. (3) the surface of the printing medium In, (4) as described above, the dispersion medium forming the ink composition is changed from water to a water-soluble or water-insoluble organic solvent, (5)
In the case of a water-based ink composition, a surface tension adjusting agent may be added, or the mixing ratio of water and a water-soluble organic solvent may be adjusted.

[0057]

EXAMPLES Example 1 Water-based colloidal gold [Nippon Paint
Co., Ltd., gold particle content concentration 19% by weight, average particle size of gold particles 0.04 μm] 20.0 parts by weight and the following components are stirred and mixed, and then a 1.0 μm membrane filter is used. The resulting composition was filtered to prepare an ink composition. The content ratio of the gold particles to the total amount of the ink composition was 3.8% by weight.

[0058] Example 2 Instead of gold colloid, water-based silver colloid [Nippon Paint
An ink composition was manufactured in the same manner as in Example 1 except that 20.0 parts by weight of silver particle-containing concentration of 30% by weight, average particle diameter of silver particles of 0.02 μm ”were used. The content ratio of silver particles to the total amount of the ink composition was 6% by weight.

Example 3 As the surface tension adjusting agent, 0.3 parts by weight of Surfynol 104E [acetylene glycol nonionic surfactant manufactured by Air Products, Inc.] was used in place of Surflon S-111, and pure water was added. An ink composition was produced in the same manner as in Example 2 except that the amount was 58.6 parts by weight. The content ratio of silver particles to the total amount of the ink composition was 6% by weight.

Example 4 An ink composition was produced in the same manner as in Example 3 except that the amount of Surfynol 104E was 0.1 part by weight and the amount of pure water was 58.8 parts by weight. The content ratio of silver particles to the total amount of the ink composition was 6% by weight. Example 5 An ink composition was produced in the same manner as in Example 2 except that the surface tension adjusting agent was not added and the amount of pure water was 58.9 parts by weight. The content ratio of silver particles to the total amount of the ink composition was 6% by weight.

Example 6 Pink aqueous dye [WATE manufactured by Orient Chemical Co., Ltd.
R PINK] 4.8 parts by weight, the amount of silver colloid is 4.0 parts by weight, and the amount of pure water is 70.0.
An ink composition was produced in the same manner as in Example 2 except that the parts by weight were used. The content ratio of silver particles to the total amount of the ink composition was 1.2% by weight. Comparative Example 1 Instead of the gold colloid, 9.2 parts by weight of an aqueous pigment paste containing flake-shaped aluminum particles (manufactured by ECART, aluminum particle content concentration 65% by weight, average particle size of aluminum particles 10.0 μm) was used. In addition, an ink composition was produced in the same manner as in Example 1 except that the amount of pure water was 69.6 parts by weight. The content ratio of aluminum particles to the total amount of the ink composition is 5.98% by weight.
Met.

The following tests were carried out on the ink compositions prepared in the above Examples and Comparative Examples to evaluate their properties. Ink Particle Size Measurement and Ejection Stability Test I The ink compositions of Examples 1 to 6 and Comparative Example 1 were applied to a thermal inkjet type inkjet printer [Desk Jet970Cx manufactured by Nippon Hewlett-Packard Co., Ltd.].
The ink cartridge for i] was filled and loaded in the inkjet printer. Then, the particle size of the ink composition discharged from the nozzle of the printer is measured by an ink particle size measuring device [Microtrack UPA manufactured by Nikkiso Co., Ltd.].
Was measured using.

Further, using the above-mentioned ink jet printer, a commercially available glossy paper, which is a porous material to be printed, was applied to Example 1.
A line having a line width of 0.5 points was printed with the ink composition of Comparative Example 1 to Comparative Example 1. Then, the line was visually observed and evaluated according to the following criteria. X: The line was broken on the way. The ejection stability was evaluated as poor. B: The line was faint at the start of printing, but could be printed without interruption in the middle. It was evaluated that the ejection stability reached a practical level.

◯: The line could be printed without blur at the start of printing and without interruption during printing.
The ejection stability was evaluated as good. The above results are shown in Table 1.

[0065]

[Table 1]

From the table, the ink compositions of Examples 1 to 6 are
It was found that the particle size of the ink composition was remarkably smaller than that of Comparative Example 1 and the ejection stability was good. The reason for this is that the aluminum particles used in Comparative Example 1 have a large particle size, their shapes are irregular, and their dispersion stability is poor. In contrast to the occurrence of clogging, the gold particles and silver particles of colloidal origin used in Examples 1 to 6 have small particle diameters and uniform shapes, and are excellent in dispersion stability. It was considered that this was because neither separation nor sedimentation occurred in the product, nor did the head clog.

Printing Characteristic Test I Using the above-mentioned ink jet printer, as a porous material to be printed, Oken type smoothness is 2100 seconds, JIS
Z8471 60 degree specular gloss defined in _-1997 3
After performing solid printing with the ink compositions of Examples 1 to 6 on the entire surface of the printable area on the surface of the glossy paper having an angle of 9.9 degrees [Inkjet glossy paper QP manufactured by Konica Corporation], The 20 ° specular gloss of the printed surface was measured. The Oken type smoothness of glossy paper was measured using an Oken type air permeability and smoothness tester KY6 manufactured by Asahi Seiko Co., Ltd. Also 60 degrees and 20
Degree of specular gloss is Handy Gloss Meter P made by Nippon Denshoku Industries
It was measured using C-1M.

In the ink composition of Comparative Example 1, clogging occurred at the initial stage of printing and a print surface having a measurable area could not be formed. Therefore, the ink compositions of Examples 1 to 6 and Comparative Example 1 were impregnated into the ink storage member of the marker pen to assemble a marker pen, and the marker pen was used to apply the same glossy paper surface as the above to the printed surface. After writing, the 20-degree specular glossiness of the writing surface was measured and used as a substitute for the measurement result of Comparative Example 1. The results are shown in Table 2.

It is clear from the results of Examples 1 to 6 in the upper and lower rows of the table that the measurement result of the writing surface with the marker pen can be used as a substitute for the measurement result of the printing surface. That is, the measurement results of the 20-degree specular gloss of Examples 1 to 6 are substantially the same on the printing surface of the inkjet printer and the writing surface of the marker pen. Therefore, for Comparative Example 1 in which the printed surface could not be formed,
We decided to use it as a substitute for the measurement result of the writing surface with a marker pen.

[0070]

[Table 2]

From the results in the upper part of the table, the printed surfaces formed on the surfaces of the glossy papers using the ink compositions of Examples 1 to 6 all had a 20 degree specular gloss of 75 degrees or more and were smooth. It was confirmed to have metallic luster. In particular, when the ink composition of Example 6 was used, a bright red printed surface having a metallic luster could be formed. On the other hand, from the results in the lower part of the table, even when the printing layer was formed on the surface of the same glossy paper using the ink composition of Comparative Example 1, the 20-degree specular gloss did not reach 75 degrees, and the smooth metal It turned out that no gloss was obtained. It is considered that this is because the aluminum particles used in Comparative Example 1 had a large particle size, and thus the granular feeling of the individual particles was conspicuous.

Printing Characteristic Test II Using the ink jet printer described above, the ink composition of Example 2 was used to print a solid image on the entire surface of the printable area on the surface of each of various types of porous printing materials described below. After that, the 20 ° specular gloss of the printed surface was measured. Substrate 1: Same as above, Oken smoothness is 2100 seconds,
Glossy paper with a 60 degree specular gloss of 39.9 degrees [Konica
Inkjet glossy paper QP manufactured by Incorporated] Printed material 2: Oken type semi-glossy paper with smoothness of 380 seconds and 60-degree specular gloss of 14.9 degrees [MC of Epson Corporation]
Semi-glossy paper] Printed material 3: Oken type smoothness of 650 seconds, 60 degree glossy film with a specular gloss of 40.4 degrees (manufactured by Epson Corporation) Printed body 4: Oken type smoothness 2.5 seconds, OHP film having a 60 degree specular gloss of 128.4 degrees [manufactured by Hewlett Packard] Printed material 5: Oken type smoothness of 175 seconds, 60 degree specular gloss of 10.3 degrees A special paper for inkjet printers [Super Fine manufactured by Epson Corporation] Printed material 6: Oken type matte paper with a smoothness of 20 seconds and a mirror gloss of 60 degrees of 6 degrees [PM of Epson Corporation] Matte Paper] The results are shown in Table 3.

[0073]

[Table 3]

From the table, it is confirmed that the ink composition of Example 2 has an Oken type smoothness of 200 seconds or more, or JIS Z
8471 60 degree specular gloss defined in _-1997 20
It is possible to form a printed surface having a smooth metallic luster having a 20-degree specular gloss of 75 degrees or more by printing on the surface of a porous printing medium (printing bodies 1 to 4) having a degree of at least 75 degrees. confirmed. Printing characteristic test III PE that has not been treated as a non-porous substrate
T film [DIAFOIL S-100 manufactured by Mitsubishi Kagaku Polyester Film Co., Ltd., thickness 50 μm] was used. The PE of the ink compositions of Examples 1 to 6 and Comparative Example 1
The contact angle with respect to the T film was measured using a contact angle meter CA-D manufactured by Kyowa Interface Science Co., Ltd.

Next, using the ink jet printer described above, solid printing was performed on the entire surface of the printable area on the surface of the PET film with the ink compositions of Examples 1 to 6, and then the printing surface was printed. The 20 degree specular gloss was measured.
Further, in Comparative Example 1, the result of measuring the 20 ° specular gloss of the writing surface with the marker was used as a substitute as in the above. The above results are shown in Table 4.

[0076]

[Table 4]

From the table, only when a combination of the two in which the contact angle of the ink composition with respect to the PET film is 35 degrees or less is selected (Examples 1, 2, and 6), there is no cissing and a 20 degree specular gloss is obtained. It was confirmed that a printed surface having a smooth metallic luster of 75 degrees or more can be formed.
The ink composition of Comparative Example 1 had a contact angle with the PET film of 35 degrees or less and could form a print surface without repellency, but the 20-degree specular glossiness did not reach 75 degrees and a smooth metallic gloss was obtained. I found that I could not get it. It is considered that this is because the aluminum particles used in Comparative Example 1 had a large particle size, and thus the granular feeling of the individual particles was conspicuous.

Example 7 An ink composition was produced in the same manner as in Example 2 except that the amount of aqueous silver colloid was 3.3 parts by weight and the amount of pure water was 75.5 parts by weight. The content ratio of silver particles to the total amount of the ink composition was 1% by weight. Example 8 An ink composition was produced in the same manner as in Example 2 except that the amount of aqueous silver colloid was 10.0 parts by weight and the amount of pure water was 68.8 parts by weight. The content ratio of silver particles to the total amount of the ink composition was 3% by weight.

Example 9 An ink composition was prepared in the same manner as in Example 2 except that the amount of aqueous silver colloid was 50.0 parts by weight and the amount of pure water was 28.8 parts by weight. The content ratio of silver particles to the total amount of the ink composition was 15% by weight. Example 10 An ink composition was produced in the same manner as in Example 2 except that the amount of aqueous silver colloid was 66.7 parts by weight and the amount of pure water was 12.1 parts by weight. The content ratio of silver particles to the total amount of the ink composition was 20% by weight.

The ink composition of each of the above Examples was subjected to the above-mentioned ejection stability test I and printing characteristic test I.
The results are shown in Table 5 together with the results of Example 2.

[0081]

[Table 5]

According to the table, when the content ratio of the silver particles contained in the silver colloid with respect to the total amount of the ink composition is in the range of 1 to 20% by weight, the ejection stability is at a practical level.
Moreover, the printing surface formed on the surface of the glossy paper is 20
It was confirmed that the specular gloss was 75 degrees or more and that it had a smooth metallic luster. However, in Example 7 in which the content ratio of the silver particles was 1% by weight, while the other Examples had a beautiful silver color tone, the color was slightly yellowish silver. Further, in Example 10 in which the content ratio of the silver particles was 20% by weight, the ejection stability in the other Examples was ◯, whereas it was Δ. And from this,
The content ratio of silver particles is 3 to 15 even within the above range.
It has been found that weight percent is preferred.

Example 11 Ethanol-based silver colloid (manufactured by Nippon Paint Co., Ltd., concentration of silver particles: 30% by weight, average particle size of silver particles: 0.02 μm)
m] 20.0 parts by weight, 4.0 parts by weight of polyvinylpyrrolidone as a binder resin, 0.6 parts by weight of ethylamine hydrochloride, and 75.4 parts by weight of ethanol as a dispersion medium were stirred and mixed. Then, it filtered using a 1.0-micrometer membrane filter and manufactured the ink composition. The content ratio of silver particles to the total amount of the ink composition was 6% by weight.

Ejection Stability Test II The ink composition of Example 11 was mixed with a continuous type ink jet printer [Vide Jet manufactured by Video Jet Co., Ltd.
The line of which the line width is 0.5 point is printed on the surface of the glossy paper. When the line was visually observed and evaluated according to the above criteria, the ejection stability was evaluated as good (◯).

Printing Characteristic Test IV Using the above continuous type ink jet printer, the Oken type smoothness of 2 as a porous material to be printed is obtained.
100 seconds, as specified in _{JIS Z8471 -1997} 6
Glossy paper with 0 degree specular gloss of 39.9 degrees [Konica Corporation
Of the ink-jet glossy paper QP] produced by the present invention, solid printing was performed by the ink composition of Example 11 on the entire printable area, and then the 20 degree specular gloss of the printed surface was measured to be 480 degrees. Met.

For comparison, the ink composition of Example 11 was impregnated into the ink occlusion member of the marker pen to assemble a marker pen, and the marker pen was used to prepare the same glossy paper surface as the printed surface. After writing the solid,
When the 20 degree specular gloss of this writing surface was measured,
After all it was 480 degrees. Printing characteristic test V As the non-porous printing medium, the same PET film as described above, which was not treated, was used. Then, the contact angle of the ink composition of Example 11 with respect to the PET film was measured using a contact angle diameter CA-D manufactured by Kyowa Interface Science Co., Ltd., and it was 3 degrees.

Next, solid ink was printed with the ink composition of Example 11 on the entire surface of the printable area on the surface of the PET film using the continuous type ink jet printer, and then printing was performed. The 20 ° specular gloss of the surface was measured and found to be 1020 °. The above results are summarized in Table 6.

[0088]

[Table 6]

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Claims (5)

[Claims] 1. An ink composition comprising a dispersion medium containing a metal colloid. 2. The ink composition according to claim 1, wherein the content of the metal particles in the metal colloid is 1 to 20% by weight based on the total amount of the ink composition. 3. The ink composition according to claim 1, which is for printing by an inkjet method. 4. The ink composition according to any one of claims 1 to 3, which has an Oken type smoothness of 200 seconds or more, or JI.
S Z8471 _-1997 60 degree specular gloss as defined by the prints to the surface of the printing material porous is at least 20 degrees, at 20 degree specular gloss defined above JIS _{Z8471 -1997} 75 degrees A printing method characterized by forming a certain printing surface. Of 5. The ink composition according to any of claims 1 to 3, JIS R3257 _- contact angle measured according to the sessile drop method defined in ₁₉₉₉ nonporous of the printing which is 35 degrees or less on the surface of the body, by printing using the ink composition, printing method characterized by forming the printing surface is 75 degrees or more 20-degree specular glossiness specified in JISZ8471 _-1997.