JP2002053779A - Water base ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water base ink composition which excels in discharge stability with minimal foaming and does not cause the clogging of a nozzle for inkjet recording to increase printing density and is easy to handle. SOLUTION: The water base ink composition comprises 1-30 wt.% surface modifying pigment dispersible and/or soluble in an aqueous medium without using a dispersing agent, 0.01-5 wt.% organic amine compound having a propanol skeleton, and water. Further, the above water base ink composition comprises, as the organic amine compound having a propanol skeleton, any one of the compounds of formula A to formula D (wherein R1 and R2 are each independently hydrogen or a 1-8C alkyl or hydroxyalkyl group which may be branched; and R3 is hydrogen or a methyl group). Furthermore, the water base ink composition comprises, as the surface modifying pigment, a pigment to the surface of which a hydrophilic functional group and/or its salt is bonded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ink which has excellent ejection stability and does not cause clogging of nozzles when used as an ink jet recording ink.

[0002]

2. Description of the Related Art An ink jet recording system is a system in which ink droplets are ejected directly from a very fine nozzle onto a recording medium and adhered to obtain characters and images. There are many operating principles such as a deflection method, a cavity method, a thermojet method, a bubble jet (registered trademark) method, and a thermal ink jet method. In any of the ink jet recording methods, ink droplets are continuously discharged from fine nozzles. Must be discharged stably. For this reason, the ink for inkjet recording is required to have high ejection stability in addition to high image quality and robustness (water resistance and light resistance) of a recorded image and to prevent nozzle clogging.

[0003] Ink-jet recording inks are often water-based inks from the viewpoints of handleability and safety. Aqueous inks can be broadly divided into dye inks and pigment inks. For dye inks, for example,
JP-A-8-60053 discloses a dye ink containing an organic amine such as tripropanolamine as an ink having excellent ejection stability. On the other hand, pigment inks are more excellent in image fastness than dye inks, and the development of ink jet recording inks that take advantage of the properties is desired, but the ejection stability is inferior to dye inks, There is a disadvantage that nozzle clogging due to sedimentation / agglomeration of the pigment easily occurs. For this reason, improving the ejection stability of the pigment ink is a technical problem that must be solved by all means.

As an attempt to improve the ejection stability of pigment ink, for example, JP-A-6-264016 discloses a pigment, a polymer dispersant, a water-soluble organic solvent, a drying inhibitor and an organic amine. An ink jet recording ink containing the above is disclosed. However, although this ink contains aminomethylpropanol, which is an organic amine compound having a propanol skeleton that can provide excellent ejection stability, the action of the polymer dispersant may cause the defoaming property to decrease and cause foaming. As a result, there was a possibility that the ejection stability was reduced. Also, in this ink, when increasing the pigment content in order to increase the print density, the polymer dispersant content must be increased in proportion to it, but a small amount of the polymer dispersant increases the viscosity of the ink. Therefore, a large amount cannot be contained in the ink. Therefore, in this ink, the content of the pigment could not be increased much, and as a result, the print density could not be sufficiently increased.

Accordingly, it is an object of the present invention to provide an ink jet recording ink which is hardly foamed, has excellent ejection stability, does not cause clogging of nozzles when used as an ink for ink jet recording, and has a sufficiently high print density. An object of the present invention is to provide a water-based ink composition that can be easily handled.

[0006]

Means for Solving the Problems The present inventors have conducted various studies on aqueous ink compositions, and as a result, together with an organic amine compound having a propanol skeleton, as a pigment,
By using a surface-modified pigment that can be dispersed and / or dissolved in an aqueous medium without a dispersant, the content of the pigment is increased to a level that has almost no foaming, is excellent in ejection stability, and has a sufficient print density. It has been found that a possible ink is obtained.

The present invention has been made based on the above findings, and contains at least a surface-modified pigment which can be dispersed and / or dissolved in an aqueous medium without a dispersant, an organic amine compound having a propanol skeleton, and water. The object has been achieved by providing an aqueous ink composition.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the aqueous ink composition of the present invention will be described in detail. As described above, the aqueous ink composition of the present invention contains a surface-modified pigment, an “organic amine compound having a propanol skeleton” (hereinafter, referred to as an organic amine), and water as essential components.

The surface-modified pigment contained in the aqueous ink composition of the present invention can be dispersed and / or dispersed in an aqueous medium without a dispersant.
Or a pigment that can be dissolved. "Dispersion and / or dissolution in an aqueous medium without a dispersant" refers to a state in which a dispersoid (pigment) is stably present at a minimum particle size that can be dispersed in an aqueous medium without using a dispersant. Say. Here, the “dispersant” refers to an additive such as a surfactant or a polymer material generally used for dispersing a pigment in an aqueous medium. The term "minimum particle size that can be dispersed" refers to the minimum particle size of the dispersoid which does not become smaller even if the dispersion time is increased.

The surface-modified pigment is obtained by bonding a “hydrophilic functional group and / or a salt thereof” (hereinafter referred to as a dispersibility-imparting group) to the surface of the pigment. The dispersibility-imparting group may be directly bonded to the pigment surface, or may be bonded via an alkyl group, an alkyl ether group, an aryl group, or the like.

The hydrophilic functional group is selected from the group consisting of a carboxyl group, a carbonyl group, a hydroxyl group, a sulfone group, a phosphate group and a quaternary ammonium salt.
Species or two or more species.

Examples of the pigment used as a raw material of the surface-modified pigment include carbon black and pigments such as Pigment Yellow, Pigment Red, Pigment Violet, Pigment Blue and Pigment Black described in Color Index, and phthalocyanine-based pigments. And azo, anthraquinone, azomethine, and condensed ring pigments. In addition, yellow No. 4, No. 5, No. 20
No. 5, No. 401; Orange No. 204; Red No. 104, 201
No. 202, 204, 220, 226-228
Organic pigments such as No. 405 and Blue No. 1 and 404, and inorganic pigments such as titanium oxide, zinc oxide, zirconium oxide, iron oxide, ultramarine, navy blue, and chromium oxide can also be used.

The surface-modified pigment is prepared by subjecting the pigment to physical or chemical treatment to bond (graft) the dispersibility-imparting group or the active species having the dispersibility-imparting group to the surface of the pigment. ). Examples of the physical processing include a vacuum plasma processing and the like. Further, as the chemical treatment, for example,
A method of oxidizing the pigment surface with an oxidizing agent in water to directly bond a carboxyl group or a sulfone group to the pigment surface,
A method in which p-amino-benzoic acid is bonded to the pigment surface to bond a carboxyl group via a phenyl group is exemplified.

The surface-modified pigment has an average particle size of 1 from the viewpoint of storage stability of the ink and prevention of nozzle clogging.
To 300 nm, preferably 10 to 200 nm.
Is more preferable.

The surface-modified pigment is contained in the aqueous ink composition of the present invention preferably in an amount of 1 to 30% by weight, more preferably 3 to 10% by weight. When the content is less than 1% by weight, the print density is insufficient, and when the content is more than 30% by weight, the viscosity may increase or nozzles may be clogged when used as ink for inkjet recording.

The organic amine contained in the aqueous ink composition of the present invention is a compound represented by any one of the following general formulas (A) to (D).

[0017]

Embedded image (Wherein, R ₁ and R ₂ each independently represent a hydrogen atom or an optionally branched alkyl or hydroxyalkyl chain having 1 to 8 carbon atoms. R ₃ represents a hydrogen atom or a methyl group Represents.)

In the above general formulas (A) to (D), R ₁
And R ₂ each independently represent a hydrogen atom or an optionally branched alkyl chain or hydroxyalkyl chain having 1 to 8 carbon atoms. Examples of the “optionally branched alkyl chain having 1 to 8 carbon atoms” include a methyl group,
Ethyl group, isopropyl group, tert-butyl group, 2-
Examples include a methylheptyl group and an n-octyl group. Examples of the “optionally branched hydroxyalkyl chain having 1 to 8 carbon atoms” include, for example, a hydroxymethyl group, a hydroxyethyl group, a hydroxyisopropyl group,
And a hydroxy-tert-butyl group. R ₁
And as the R _2, hydroxyethyl group, hydroxy isopropyl group, hydroxy -tert- butyl group is particularly preferred. R ₃ in the general formula (B) represents a hydrogen atom or a methyl group, and a methyl group is particularly preferable.

Examples of the organic amine include aminomethylpropanol, tripropanolamine, N- (2
-Hydroxypropyl) triethylenetetramine, (2-hydroxypropyl) dimethylamine, N, N-bis (2-hydroxypropyl) -tert-butylamine, hydroxyisopropyltriethyleneamine, hydroxyisopropyldiisopropylamine, hydroxyisopropyldibutylamine, dihydroxy Isopropylethylamine, dihydroxyisopropyl-n-butylamine, dihydroxyisopropyl-tert-butylamine, N, N
-Bis (2-hydroxypropyl) -N-hydroxyethylamine and N-2-hydroxypropyl-N, N-bis (hydroxyethyl) amine, etc., and one or more of these are used. Especially tripropanolamine,
It is preferable to use aminomethylpropanol, N, N-bis (2-hydroxypropyl) -tert-butylamine and the like.

The organic amine is contained in the aqueous ink composition of the present invention preferably in an amount of 0.01 to 5% by weight, more preferably 0.05 to 2% by weight. If the content is less than 0.01% by weight, there is no effect on the ejection stability.
Adjustment may be difficult.

The water contained in the aqueous ink composition of the present invention is a main solvent, and pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water or ultrapure water can be used.
In particular, it is preferable to use water that has been sterilized by ultraviolet irradiation, addition of hydrogen peroxide, or the like, in order to prevent generation of mold and bacteria and to enable long-term storage of the ink.

Water is contained in the aqueous ink composition of the present invention preferably at 30 to 90% by weight, more preferably at 40 to 80% by weight.

The aqueous ink composition of the present invention contains the above-mentioned components (surface-modified pigment, organic amine and water), and is free from foaming, has excellent ejection stability, and is easy to handle. However, if necessary, various components described below can be contained.

It is preferable that the aqueous ink composition of the present invention further contains a penetration enhancer from the viewpoint of enhancing the permeability to the recording medium. As the penetration enhancer, one that can lower the surface tension of an aqueous solution (aqueous ink composition) and increase the permeability (wetting property) of the aqueous solution to a recording medium is used. Solvents and / or surfactants are used.

Examples of the water-soluble organic solvent include lower alcohols such as ethanol and propanol, cellosolves such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, and carbitols such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether. And ethylene glycol mono-n-butyl ether, diethylene glycol-n-butyl ether, triethylene glycol-n
And glycol ethers such as -butyl ether, and one or more of these are used. Among these, glycol ethers are particularly preferable in that a high quality recorded matter with almost no ink bleeding can be provided.

Further, as the surfactant, for example,
Examples include anionic surfactants such as fatty acid salts and alkyl sulfate salts, nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether, cationic surfactants and amphoteric surfactants. And one or more of these are used. Among them, it is particularly preferable to use a nonionic surfactant from the viewpoint of suppressing the generation (foaming) of bubbles in the ink.

Preferred examples of the nonionic surfactant include, for example, Nissan Nonion K-211 and K
-220, P-213, E-215, E-220, S-
215, S-220, HS-220, NS-212, N
S-220 (all trade names, manufactured by NOF Corporation) and the like, and one or more of these are used. In particular, Surfynol 61, 82, 104, 440, 465,
It is preferable to use an acetylene glycol-based surfactant such as 485 (all trade names, manufactured by Air Products and Chemicals). An ink containing an acetylene glycol-based surfactant has almost no foaming and is particularly excellent in ejection stability, and is suitable for an ink jet recording method.

The penetration enhancer is contained in the aqueous ink composition of the present invention preferably in an amount of 0.001 to 5% by weight, more preferably 0.005 to 2% by weight. Content 0.0
If it is less than 01% by weight, there is no effect in promoting ink permeability, and if it is more than 5% by weight, the ejection stability of the aqueous ink composition may be reduced.

The aqueous ink composition of the present invention may contain a humectant from the viewpoint of further improving the ejection stability. As the humectant, for example, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-
Propanediol, 1,4-butanediol, 1,5-
Pentanediol 1,6-hexanediol, 1,2,2
Polyols such as 6-hexanetriol and pentaerythritol, lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone and ε-caprolactam, urea, thiourea, ethylene urea, 1,3-dimethylimidazolidinone and the like And saccharides such as maltitol, sorbitol, gluconolactone, and maltose, and one or more of these are used.

The humectant is preferably 1 to 30% by weight, more preferably 5 to 2% by weight in the aqueous ink composition of the present invention.
0% by weight is contained.

From the same viewpoint, the aqueous ink composition of the present invention may contain a fungicide and a preservative. Examples of the fungicides and preservatives include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, and 1,2-dibenzisothiazolin-3-one. (Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN, manufactured by AVECIA), and one or more of these can be used.

The antifungal agent / preservative is preferably contained in the aqueous ink composition of the present invention in an amount of 0.001 to 3% by weight, more preferably 0.01 to 1% by weight.

The aqueous ink composition of the present invention may further contain, if necessary, additives such as a viscosity modifier, an antioxidant, an ultraviolet absorber, a chelating agent and an oxygen absorber. One or more kinds are used.

The water-based ink composition of the present invention has a permeation time of 1 mg / cm ² when applied to a recording medium from the viewpoint of providing good recorded matter with little bleeding.
Preferably, it has a permeability such that it is less than a second. Here, the penetrability such that “permeation time when the amount of application to the recording medium is 1 mg / cm ² is less than 1 second” means that 50 ng of the aqueous ink composition is applied to the recording medium over an area of 360
Immediately after coating at dpi (dot / inch) × 360 dpi, the penetration of the water-based ink composition such that the time required for the water-based ink composition to clean the coated surface even after touching the coated surface is less than 1 second. Refers to sex. At this time, as a recording medium, neutral plain paper (for example, trade name “Xerox-
P ", manufactured by Fuji Xerox Co., Ltd.). Such permeability can be imparted by incorporating the above-mentioned predetermined amount of the penetration enhancer into the aqueous ink composition.

From the same viewpoint, the aqueous ink composition of the present invention preferably has a surface tension of less than 40 mN / m, more preferably 35 mN / m. The surface tension is measured according to JIS K3362-1978. The adjustment of the surface tension can be performed by including the above-mentioned predetermined amount of the penetration enhancer in the aqueous ink composition.

The aqueous ink composition of the present invention has a viscosity at 25 ° C. of 1 to 25 from the viewpoint of ejection stability.
mPa · s, preferably 1 to 15 mPa · s
Is more preferable. Viscosity is JIS Z880
Measured according to 3-1991. The viscosity is adjusted in the aqueous ink composition by using a viscosity modifier such as rosins, alginic acids, polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyacrylate, polyvinyl pyrrolidone, and gum arabic starch. Can be carried out.

The aqueous ink composition of the present invention has a pH of from 6 to 1 from the viewpoint of improving the printing density and the stability of the liquid.
It is preferably 0, more preferably 7 to 9.5. The pH can be adjusted by adding the organic amine, which is an alkaline agent, to the aqueous ink composition in the predetermined amount.

The aqueous ink composition of the present invention can be prepared using a conventionally known apparatus, for example, a ball mill, a sand mill, an attritor, a basket mill, a roll mill, or the like, in the same manner as a conventional ink. At the time of preparation, it is preferable to remove coarse particles from the viewpoint of preventing nozzle clogging. The coarse particles can be removed by, for example, filtering the ink obtained by mixing the above components using a filter such as a membrane filter or a mesh filter, and preferably removing particles of 10 μm or more, more preferably 5 μm or more. This is done by:

The aqueous ink composition of the present invention can be suitably used in any recording method in which printing is performed by attaching the aqueous ink composition to a recording medium. Examples of such a recording method include, for example, an ink jet recording method which is a recording method in which droplets of an aqueous ink composition are ejected and the droplets are attached to a recording medium to perform printing, a recording method using a writing instrument such as a pen, Other various printing methods can be mentioned, and it is particularly preferable to use it for an ink jet recording method, especially for an on-demand type ink jet recording method.
Examples of the on-demand type ink jet recording method include, for example, a piezoelectric element recording method for performing recording using a piezoelectric element disposed on a printer head, and using heat energy from a heater of a heating resistor element disposed on the printer head. And a thermal jet recording method in which recording is performed by any of the methods described above.

The aqueous ink composition of the present invention is excellent in ejection stability by the action of the organic amine, and contains a dispersant by using the surface-modified pigment containing no dispersant. There is almost no foaming as compared with ordinary inks. For this reason, the aqueous ink composition of the present invention,
It is extremely excellent in ejection stability, and does not cause clogging of nozzles when used as ink for inkjet recording. Further, since the aqueous ink composition of the present invention does not contain a dispersant, the content of the pigment can be increased to a level having a sufficient print density as compared with a normal pigment ink containing a dispersant. It is easy to handle. Further, the aqueous ink composition of the present invention containing the penetration enhancer can provide a good quality recorded matter with almost no ink bleeding, and does not cause bleeding even when used for multicolor printing. The applicable recording medium is wide.

[0041]

EXAMPLES Examples of the aqueous ink composition of the present invention are shown below. However, it goes without saying that the present invention is not limited to such an embodiment.

Examples 1 to 6 and Comparative Examples 1 to 3 Aqueous ink compositions having the compositions shown in Table 1 below were prepared.
For the preparation, each component was mixed at 25 ° C. and stirred for 2 hours, and then, using a 5 μm diameter membrane filter, 2 kg /
This was performed by pressure filtration at a pressure of cm ² . In Examples 1 to 6, the compound No. shown in the following [Chemical Formula 3] was used as the alkaline agent. 1 to 6 were used (all were the above-mentioned organic amines). In Comparative Example 1, KOH was used. In Comparative Examples 2 and 3, the compound No. 7 and 8
Were used (all compounds outside the scope of the present invention).
Each of the pigment dispersions used in Examples 1 to 6 and Comparative Examples 1 to 3 is a surface-modified pigment dispersion in which a pigment is stably dispersed in an aqueous medium without using a dispersant. However, the added amount of the pigment dispersion in Table 1 below is calculated in terms of the solid content of the pigment.

[0043]

[Table 1]

[0044]

Embedded image

[Evaluation of Clogging Resistance] Each of the aqueous ink compositions of Examples 1 to 6 and Comparative Examples 1 to 3 was evaluated by the following <Evaluation method of clogging resistance>. The results are shown in Table 2 below.

<Evaluation Method of Clogging Resistance> The aqueous ink composition was filled into a piezoelectric element type ink jet recording apparatus (trade name “MJ-930C”, manufactured by Seiko Epson Corporation), and printing was performed. It was confirmed that the ink composition was discharged stably. Thereafter, the ink jet recording apparatus was left for 4 weeks in an environment at a temperature of 50 ° C. and a relative humidity of 40% with the print head part removed from the home position. After the standing, the inkjet recording apparatus was moved to an environment at normal temperature, and after waiting for the temperature to drop to normal temperature, the main body power was turned on, printing was performed again, and the ejection state of the aqueous ink composition was visually observed. At this time, if the ejection is not stable, the cleaning operation of the predetermined head unit of the inkjet recording apparatus is performed, and the head unit required until the aqueous ink composition is stably ejected (returns). The number of cleaning operations was evaluated and evaluated according to the following evaluation criteria. <Evaluation Criteria> A: Ejection after standing is extremely stable, and no cleaning operation of the head is required. B: Discharge after standing was unstable, and 2
Up to cleaning operations are required. C: The ejection after standing was unstable, and the head portion 3
Up to five cleaning operations are required. NG: The ejection after standing was unstable, and the head section was not restored even after cleaning was performed six times or more.

[0047]

[Table 2]

As is evident from the results shown in Table 2, all of the aqueous ink compositions of Examples 1 to 6 containing the organic amine exhibited excellent clogging resistance. In contrast,
All of the aqueous ink compositions of Comparative Examples 1 to 3 did not contain the organic amine and resulted in poor clogging resistance. Further, the aqueous ink compositions of Examples 3 to 6 containing a penetration enhancer all gave good quality recorded matter with little bleeding. Further, Surfynol 46, which is an acetylene glycol-based surfactant, is used as a nonionic surfactant.
The aqueous ink compositions of Examples 5 and 6 containing No. 5 showed extremely little foaming and were easy to handle.

[0049]

According to the water-based ink composition of the present invention, there is almost no foaming, the ejection stability is excellent, and there is no possibility that nozzle clogging will occur when used as an ink for ink jet recording. Further, the aqueous ink composition of the present invention,
Since it does not contain a dispersant, it is easy to handle, for example, the pigment content can be increased to a level having a sufficient print density as compared with a normal pigment ink containing a dispersant.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2C056 EA05 FA03 FA04 FC02 2H086 BA52 BA53 BA55 BA59 BA60 BA62 4J039 AE07 BA04 BC06 BC07 BC09 BC13 BC14 BC15 BC19 BC35 BC54 BE01 BE12 BE22 BE28 BE33 CA03 CA06 EA41 EA44 EA48 GA24

Claims (18)

[Claims] 1. An aqueous ink composition containing at least a surface-modified pigment which can be dispersed and / or dissolved in an aqueous medium without a dispersant, an organic amine compound having a propanol skeleton, and water. 2. The aqueous ink composition according to claim 1, wherein the organic amine compound having a propanol skeleton is a compound represented by any one of the following general formulas (A) to (D). Embedded image (Wherein, R ₁ and R ₂ each independently represent a hydrogen atom or an optionally branched alkyl or hydroxyalkyl chain having 1 to 8 carbon atoms. R ₃ represents a hydrogen atom or a methyl group Represents.) 3. The method according to claim 1, wherein the surface-modified pigment is 1 to 30% by weight and the organic amine compound having a propanol skeleton is 0.1% by weight.
The aqueous ink composition according to claim 1, wherein the water-based ink composition contains 0.01 to 5% by weight. 4. The aqueous ink composition according to claim 1, wherein the surface-modified pigment has a hydrophilic functional group and / or a salt thereof bonded to the surface of the pigment. 5. The method according to claim 1, wherein the hydrophilic functional group is a carboxyl group,
The aqueous ink composition according to claim 4, wherein the composition is at least one member selected from the group consisting of a carbonyl group, a hydroxyl group, a sulfone group, a phosphate group, and a quaternary ammonium salt. 6. The composition according to claim 1, further comprising a penetration enhancer.
6. The aqueous ink composition according to any one of 5. 7. The amount of the penetration enhancer is 0.001 to 5% by weight.
The water-based ink composition according to claim 6, which comprises: 8. The aqueous ink composition according to claim 6, wherein the penetration enhancer is a water-soluble organic solvent and / or a surfactant. 9. The aqueous ink composition according to claim 8, wherein the water-soluble organic solvent is a glycol ether. 10. The aqueous ink composition according to claim 8, wherein the surfactant is a nonionic surfactant. 11. The aqueous ink composition according to claim 10, wherein the nonionic surfactant is an acetylene glycol-based surfactant. 12. The recording medium according to claim 6, wherein the recording medium is neutral plain paper, and the penetration time is less than 1 second when the amount of application to the recording medium is 1 mg / cm ² . Aqueous ink composition. 13. The aqueous ink composition according to claim 6, having a surface tension of less than 40 mN / m. 14. The aqueous ink composition according to claim 1, which is used in an ink jet recording method. 15. The aqueous ink composition according to claim 14, wherein the ink jet recording method is an on-demand type ink jet recording method. 16. A recording method for printing by attaching the aqueous ink composition according to claim 1 to a recording medium. 17. An ink jet recording method for discharging a droplet of the aqueous ink composition according to claim 1 and attaching the droplet to a recording medium to perform printing. 18. A recorded matter recorded by the recording method according to claim 16. Description: