JP5074728B2 - Mailing ink, mailing ink tank using the ink, and mailing ink jet recording method - Google Patents

Description

The present invention relates to a mailing ink capable of forming a postal indicium that has a preferred color as blue and has excellent 2D (two-dimensional) barcode readability. Further, the present invention relates to an ink tank and an ink jet recording how mailing mailing using said ink.

  In the ink jet recording method, recording is performed by ejecting small droplets of ink and attaching the ink to a recording medium such as paper. For example, Patent Document 1 discloses a thermal ink jet recording method in which an electrothermal converter is used as a means for supplying energy and droplets are ejected by bubbles generated by applying thermal energy to ink. According to this method, a high-density multi-orifice of the recording head can be easily realized, and a high-resolution and high-quality image can be recorded at high speed.

  Using this technology, ink is used in various applications. Such applications are not limited to merely forming beautiful colored images such as photographs and business documents, but are also used for industrial applications, for example, printing large amounts of indicia in the postal business field (hereinafter also referred to as indicia) at high speed. Etc. Inkjet recording technology is used in the postal field not only in the United States and Japan but also in various European countries. For example, in Germany, France, Switzerland, etc., a mailing ink jet recording apparatus for forming a blue postal seal is put to practical use.

  Further, with the recent digitization in the postal field, a mailing system using an indicia to which information is added using a 2D barcode has been put into practical use. Since 2D barcodes can record and read a large amount of information with high density, it is possible to automate sorting and input work, save labor, and improve customer service.

  As a mailing ink, Patent Document 2 reports a fluorescent ink for a mailing system containing a water-soluble resin and a pigment that can achieve both water resistance and fluorescence intensity characteristics. In this mailing system, ink is printed as an indicia on a postal matter, and the postage, postal mail posting place, indicia recording person, etc. can be known by reading the indicia with a dedicated machine.

  On the other hand, as a blue ink, Patent Document 3 discloses an ink containing a cyan dye and a magenta dye having a specific structure in a specific ratio. This ink has a high printing density and is said to be excellent in the reliability of the recording apparatus.

  In addition, it is known to mix several kinds of color materials in order to express a target color as a printed matter. For example, Patent Document 4 discloses an ink containing both a black color material and a cyan color material. Is disclosed. However, the apparent color of any of the disclosed inks is black, and no blue ink has been reported.

Further, Patent Document 5 reports a recording apparatus that suppresses the generation of ink mist by including first and second electrodes that can apply different voltages to each other.
Japanese Patent Publication No. 61-59911 US Pat. No. 6,176,908 JP 2001-220529 A JP 2001-106946 A JP 05-000518 A

  However, with the conventional blue indicia distributed in European countries such as Germany, France and Switzerland, there are cases where it is not possible to satisfy both the preferable color and visibility as an indicia and the readability with a 2D barcode reader. .

  Accordingly, an object of the present invention is to provide a mailing ink capable of satisfying both a preferable color and visibility as an indicia and readability with a 2D barcode reader.

Another object of the present invention is to provide an ink tank and an ink jet recording how mailing mailing using such ink.

  In considering the above issues, favorable hue and saturation are defined from the viewpoint of local customs and the designation of postal service authorities, etc., and it is necessary to consider the visibility of the postal seal, It was recognized as one of the important factors that the printing part has a specific color and density.

  It was also found that there is a correlation between the spectral characteristics determined by the spectral characteristics of the light source of the barcode reader, the wavelength sensitivity characteristics of the light receiving unit, and the like, and the reflected spectral characteristics of the 2D barcode to be read. For example, it has been found that the 2D barcode printing portion has a wavelength characteristic that absorbs a wavelength region in which the sensitivity of the barcode reader is high, so that the reading rate of the 2D barcode can be improved. .

  Furthermore, as a result of studies by the present inventors, it has been necessary to consider the difference in characteristics of the barcode reader depending on the model, the stability of the reading characteristics of the barcode reader, and the like. It has also been found that in order to realize a stable reading accuracy for various mail pieces, the reflection spectrum characteristic of the printing unit needs to have a certain degree of latitude for the readability.

  The present invention has been completed in order to achieve the above object based on the above examination.

Specifically, the present invention is a mailing ink used for ink jet recording, and is obtained by applying the ink to a recording medium so that the ink application amount is 4.5 mg per square inch. Of CIE L ^* a ^* b ^{* in the} color system, a ^* is −10 or more and 15 or less, b ^* is −50 or more and −15 or less, and integrated value Ri der 90 or less, the ink contains a plurality of color material, color material said plurality of C. I. Direct Blue 199, Exemplified Compound M8 below and Exemplified Compound Bk7 below, C.I. I. The ratio of Direct Blue 199, Exemplified Compound M8 below and Exemplified Compound Bk7 below (CI Direct Blue 199: Exemplified Compound M8: Exemplified Compound Bk7) is from 1: 0.3 to 0.4: 0.1 on a mass basis. a mailing ink, wherein 0.4 der Rukoto.

Furthermore, the present invention is an ink tank and an ink jet recording how mailing mailing using ink above mailing.

  According to the present invention, it is possible to obtain a printed matter having a preferable color and excellent visibility, and to provide an ink that can be read even when a 2D barcode reader having various spectral characteristics is used. Can do. The present invention has the two problems of providing a postal indicium that is a preferable color as a postal indicium and having excellent visibility, and providing a postal indicia having a stable 2D barcode with a low reading failure rate. It is possible to provide an ink capable of achieving both high balance and good balance.

Further, according to the present invention, it is also possible to provide an ink tank and an ink jet recording how using these inks.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments of the present invention.

The present invention, in ^{a *} is -10～15 in CIE ^L * ^a * ^{b *} color system of the printing unit when it is used for a recording medium, ^{b *} is -50 to 15 and 380nm of the indicia shaped portion This is a mailing ink in which the integrated value of the reflection spectrum in the wavelength region of 730 nm is 90 or less.

  The print portion defined here is a solid-printed portion, and is a print portion when the amount of ink applied to the recording medium is 4.5 mg per inch square. This applied amount is, for example, when the discharge amount of one dot is 25 ng and ink is applied to all pixels at an image resolution of 600 × 300 dots per square inch (hereinafter referred to as “600 × 300 dpi image resolution”). Corresponds to the amount of ink applied. Further, the recording medium used preferably has a ISO whiteness of 80 to 90% and a Steecht size of 10 to 60 seconds.

When the colors (a ^* , b ^* ) of the printing portion are in the above-mentioned range, it becomes a preferable color that can be easily recognized as a blue color of a postal stamp in European countries, particularly Germany, France, Switzerland, and the like. Furthermore, since the integrated value of the reflection spectrum is below the above range, the color is not too bright and has a calm color, so visibility is improved regardless of the type of postal matter and color development characteristics suitable as a postal stamp. It becomes. In addition, the 2D barcode formed with the same ink has a low reflection spectrum in the visible light region as a whole, so the readability is improved for barcode readers with various wavelength sensitivity characteristics. It becomes possible to keep the reading defect rate low.

In the present invention, it is preferable in terms of color that a ^* is 0 to 10 and b ^* is −40 to −15 in the CIE L ^* a ^* b ^* color system of the printing unit. Further, by setting the integrated value of the reflection spectrum in the wavelength range of 380 nm to 730 nm to be 80 or less, the reading accuracy of the 2D barcode is further improved, and reading defects for various types of envelopes can be reduced. Furthermore, it is preferable to set the integrated value to 30 or more. When the integrated value is 30 or more, a preferable color is easily obtained.

  Furthermore, in the present invention, the ratio (S1 / S2) of the integrated value S1 of 380 nm to 550 nm and the integrated value S2 of 560 nm to 730 nm of the reflection spectrum is preferably 1.2 or more. If the relationship of the reflection spectrum of the printing portion is within this range, the color saturation of the printing portion is increased while maintaining high reading accuracy of the 2D barcode, and the color becomes more vivid so that the visibility is further increased. improves. Furthermore, it is preferable that S1 / S2 is 3.0 or less. When S1 / S2 is 3.0 or less, a preferable integrated value is easily obtained.

  In addition, the integrated value of the reflection spectrum in the present invention can be obtained by a conventional method using a spectrophotometer. For example, the reflection spectrum of the printed portion printed using the above-mentioned conditions using Spectrolino manufactured by Gretag, Inc., the observation light source: D50, the observation field of view: 2 degrees, the concentration: ANSI. Color measurement is performed under the conditions of A, white reference: Abs, and filter: No. The obtained reflection spectrum is expressed as the reflection intensity at every 380 to 730 nm and 10 nm (FIG. 1). The reflection intensity is 1.0 as the reflection intensity of light reflected by an ideal perfect diffuse reflection surface, that is, when the reflectance is 100%. The integrated value S of the reflection spectrum is represented by the product of the sum of the reflection intensities at the respective wavelengths and the sum of the sum and the 10 nm (wavelength width). The integrated value S of the reflection spectrum in FIG. 1 corresponds to the area of the shaded portion of 380 nm to 730 nm. Similarly, the integrated value S1 from 380 nm to 550 nm is a product of the sum of the reflection intensities of the wavelengths of 380 nm to 550 nm and 10 nm (wavelength width). The integrated value S1 of the reflection spectrum in FIG. 1 corresponds to the shaded area of 380 nm to 550 nm. The integrated value S2 from 560 nm to 730 nm is the difference between S and S1, and can be obtained from S−S1. The integrated value S2 of the reflection spectrum in FIG. 1 corresponds to the area of the shaded portion of 560 nm to 730 nm. S1 / S2 is calculated from the obtained S1 and S2.

When the ink of the present invention is printed on a recording medium, it is necessary to form a printing portion that exhibits a specific blue color and has a specific reflection spectral characteristic. For that purpose, it is preferable to contain one or more colorants having specific light absorption characteristics. As the coloring material, any dye or pigment can be used. If it is a dye, it can be appropriately selected from direct dyes, acid dyes, basic dyes, reactive dyes, disperse dyes and the like. It is. It is preferable to use a direct dye or an acid dye from the viewpoints of color developability on a recording medium and reliability in ink jet recording.
Although the preferable example of the coloring material which can be used is given below, it is not limited to these.

Examples of the blue color material include the following color materials.
C. I. Direct Blue: 1, 15, 22, 25, 41, 76, 77, 80, 86, 90, 98, 106, 108, 120, 158, 163, 168, 199, 226, 307, etc. C.I. I. Acid Blue: 1, 7, 9, 15, 22, 23, 25, 29, 40, 43, 59, 62, 74, 78, 80, 90, 100, 102, 104, 112, 117, 127, 138, 158 161, 203, 204, 221, 244, etc. I. Pigment Blue: 1, 2, 3, 15, 15: 2, 15: 3, 15: 4, 16, 22, 60 etc. C.I. I. Acid Blue: 62, 80, 83, 90, 104, 112, 113, 142, 203, 204, 221, 244, etc. C.I. I. Reactive Blue: 49 etc. C.I. I. Acid Violet: 17, 19, 48, 49, 54, 129, etc. C.I. I. Direct violet: 9, 35, 47, 51, 66, 93, 95, 99 etc. C.I. I. Reactive violet: 1, 2, 4, 5, 6, 8, 9, 22, 34, 36 etc. C.I. I. Disperse violet: 1, 4, 8, 23, 26, 28, 31, 33, 35, 38, 48, 56 etc. C.I. I. Pigment Blue: 15: 6 etc. C.I. I. Pigment Violet: 19, 23, 37, etc.

  A phthalocyanine compound represented by the following general formula (1) or a salt thereof

(In the formula, l represents 0 to 2, m = 1 to 3 and n = 1 to 3; l + m + n = 3 to 4, and the substitution position of the substituent is the 4 or 4 ′ position. M represents an alkali metal or ammonium, and R ₁ and R ₂ each independently represent any one of a hydrogen atom, a sulfonic acid group, and a carboxyl group (provided that R ₁ and R ₂ are simultaneously hydrogen atoms) And Y represents any of a chlorine atom, a hydroxyl group, an amino group, a monoalkylamino group, and a dialkylamino group.)

Among the color materials represented by the general formula (1), a phthalocyanine compound obtained by reacting a 4-sulfophthalic acid derivative or a 4-sulfophthalic acid derivative with an (anhydrous) phthalic acid derivative in the presence of a metal compound as a raw material It is preferable to use a phthalocyanine compound obtained by converting a sulfonic acid group into a chlorosulfone group and then reacting with an aminating agent in the presence of an organic amine. That is, a phthalocyanine compound into which an unsubstituted sulfamoyl group (—SO ₂ NH ₂ ) and a substituted sulfamoyl group [the following general formula (2)] are introduced is limited to positions 4 and 4 ′ in the above formula (1). The ink used as the color material has extremely excellent environmental gas resistance.

(In the formula, R ₁ and R ₂ each independently represent any of a hydrogen atom, a sulfonic acid group, and a carboxyl group (provided that R ₁ and R ₂ simultaneously become hydrogen atoms), Y Represents a chlorine atom, a hydroxyl group, an amino group, a monoalkylamino group or a dialkylamino group.)

  Specific examples of the compound represented by the general formula (2) include exemplified compounds having the following structure in the form of a free acid. Among these, Exemplified Compound C1 is particularly preferably used.

  The blue color material used in the present invention is preferably a phthalocyanine compound represented by the following formula or a salt thereof. I. Direct blue 199 is preferred.

(In the formula, l (el) = 0 to 4, m = 0 to 4, and M represents an alkali metal or ammonium.)

  In the present invention, if necessary, color materials having different hues can be mixed with the blue color material.

Examples of yellow color materials are listed below.
C. I. Direct yellow: 8, 11, 12, 27, 28, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 100, 110, 132, 173, etc. I. Acid Yellow: 1, 3, 7, 11, 17, 23, 25, 29, 36, 38, 40, 42, 44, 76, 98, 99 etc. C.I. I. Pigment Yellow: 1, 2, 3, 12, 13, 14, 15, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 128, 138, 180, etc.

  A compound represented by the following general formula (3) or a salt thereof

(In the formula, each m independently represents 1 or 2. M1 independently represents any one of a hydrogen atom, an alkali metal, an alkaline earth metal, a cation of an organic amine, and an ammonium ion.)

  Preferable examples of the color material represented by the general formula (3) are not particularly limited, but specific examples include structures as shown in Table 1 below. For convenience, the ring structures at both ends of the above general formula (3) were defined as A ring and B ring, and the substitution positions were defined as in the following general formula (4). The numbers shown in Table 1 below indicate positions where the sulfonic acid groups in the exemplary compounds Y1 to Y5 are substituted.

(In the formula, each m independently represents 1 or 2. M1 independently represents any one of a hydrogen atom, an alkali metal, an alkaline earth metal, a cation of an organic amine, and an ammonium ion.)

  Preferable examples of the coloring material represented by the general formula (4) are not particularly limited, but specific examples include the exemplified compound Y1 represented by the following formula.

  In addition, examples of the yellow color material include compounds having structures described in International Publication No. 99/43754 pamphlet and International Publication No. 02/081580 pamphlet.

Examples of magenta color materials are listed below.
C. I. Direct Red: 2, 4, 9, 11, 20, 23, 24, 31, 39, 46, 62, 75, 79, 80, 83, 89, 95, 197, 201, 218, 220, 224, 225, 226 227, 228, 229, 230 etc. C.I. I. Acid Red: 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 42, 51, 52, 80, 83, 87, 89, 92, 106, 114, 115, 133, 134, 145 158, 198, 249, 265, 289, etc. C.I. I. Food Red: 87, 92, 94, etc. I. Direct violet: 107 grade C.I. I. Pigment Red: 2, 5, 7, 12, 48: 2, 48: 4, 57: 1, 112, 122, 123, 149, 168, 170, 177, 184, 194, 202, 209, 224, etc. C.I. I. Acid Orange: 7, 8, 10, 12, 24, 33, 56, 67, 74, 88, 94, 116, 142, etc. C.I. I. Acid Red: 111, 114, 266, 374, etc. C.I. I. Direct orange: 26, 29, 34, 39, 57, 102, 118 etc. C.I. I. Food Orange: 3 etc. C.I. I. Reactive orange: 1, 4, 5, 7, 12, 13, 14, 15, 16, 20, 29, 30, 84, 107, etc. I. Disperse orange: 1, 3, 11, 13, 20, 25, 29, 30, 31, 32, 47, 55, 56 etc. C.I. I. Pigment Orange: 43 mag

  Compounds represented by the following general formulas (5) and (6) or salts thereof

(In the formula, R ₁ represents any _one of a hydrogen atom, an alkyl group, a hydroxy lower alkyl group, a cyclohexyl group, a mono- or dialkylaminoalkyl group, and a cyano lower alkyl group, and Y represents a chlorine atom, a hydroxyl group, and an amino group. , A mono- or dialkylamino group (wherein the alkyl group may have a substituent selected from the group consisting of a sulfonic acid group, a carboxyl group and a hydroxyl group), R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms and a carboxyl group (provided that all of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are (Except when it is a hydrogen atom.)

  Preferable specific examples of the coloring material represented by the general formula (5) include exemplified compounds M1 to M7 having the following structure in the form of a free acid. In the present invention, Exemplified Compound M7 is particularly preferable among these.

(In the formula, Y represents any one of a hydrogen atom, a methyl group, a methoxy group, an acetylamino group, and a nitro group, and can form a benzene ring together with the carbon atom at the 3-position of the benzene ring B. X is Represents any one of an acetyl group, a benzoyl group, a paratoluenesulfonyl group and a 4-chloro-6-hydroxy-1,3,5-triazin-2-yl group, and M ¹ , M ² and M ³ are each independently Represents any one of alkali metal and ammonium.)

  Preferable specific examples of the coloring material represented by the general formula (6) are disclosed in JP-A-59-78273, and particularly preferable ones are exemplified below. In the present invention, Exemplified Compound M8 is particularly preferable among these.

  Other magenta and red colorants include compounds described in JP-A-5-73791, US Pat. No. 5,599,386, and JP-A-9-241555.

Examples of green color materials are listed below.
C. I. Acid Green: 1, 3, 5, 6, 9, 12, 15, 16, 19, 21, 25, 28, 81, 84 etc. C.I. I. Direct green: 26, 59, 67 etc. I. Food Green: 3rd grade C.I. I. Reactive Green: 5, 6, 12, 19, 21 etc. C.I. I. Disperse Green: 6, 9 etc. C.I. I. Pigment Green: 7, 36 etc.

  In the present invention, from the viewpoint of the color tone of the postal stamp and the readability of the 2D barcode, among the above color materials, C.I. I. It is particularly preferable to use a mixture of Direct Blue 199 and Exemplary Compound M8. Further, in the case of this combination, the balance of fastness to discoloration by light or gas is excellent.

  Furthermore, in the present invention, in order to effectively improve the reading rate of 2D barcode with a small amount of color material, a black color material is used in combination with the above-described blue color material and other color materials. It is more preferable. By containing a small amount of the black color material, the reflection spectrum of the entire visible light region of the printing portion can be effectively reduced, so that the total color material content concentration in the ink can be kept low. . As a result, the viscosity of the ink can be kept low, and an increase in viscosity due to ink refill characteristics and evaporation during ejection driving at a high frequency can be preferably achieved. In addition, this configuration can improve the intermittent ejection stability in a low humidity environment, and is preferable in terms of the reliability of the printing system. Furthermore, it is preferable also in terms of cost by keeping the coloring material-containing concentration low.

The black color material is defined as follows. First, ultraviolet-visible absorption measurement of an aqueous solution or aqueous dispersion containing 0.003% by mass of a black color material is performed to obtain an absorption spectrum of 380 nm to 730 nm. Next, the obtained spectrum is converted into a CIE L ^* a ^* b ^* color system with a C light source and a viewing angle of 2 degrees, and a color material having L ^* of 60 or less is defined as a “black color material”. .

Preferred specific examples of the black color material that can be used are listed below, but are not limited thereto.
C. I. Direct black: 17, 19, 22, 31, 32, 51, 62, 71, 74, 112, 113, 154, 168, 195, etc. I. Acid Black: 2, 48, 51, 52, 110, 115, 156 etc. C.I. I. Food Black: Compound carbon black from JP 1,3,669, etc.

  Compounds represented by the following general formulas (7), (8) and (9) or salts thereof

(In the formula, R ₁ and R ₂ are each independently a hydrogen atom, a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. R ₃ and R ₄ each independently represent a hydrogen atom; an alkyl group having 1 to 4 carbon atoms; an alkoxy group having 1 to 4 carbon atoms; a hydroxyl group; a hydroxyl group or an alkoxy group having 1 to 4 carbon atoms. An alkyl group having 1 to 4 carbon atoms which may be substituted with hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms which may be substituted with a sulfonic acid group or a carboxyl group; an alkyl group Or represents an amino group substituted by an acyl group, and n is 0 or 1.)
General formula (8)

(In the formula, R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom; a hydroxyl group; an amino group; a carboxyl group; a sulfonic acid group; an alkyl group having 1 to 4 carbon atoms; An alkoxy group having 4 carbon atoms; an alkoxy group having 1 to 4 carbon atoms substituted by a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group or a carboxyl group; substituted by a phenyl group, an alkyl group or an acyl group Represents any amino group and n is 0 or 1).

  General formula (9)

(Wherein X represents a hydrogen atom and a lower alkyl group or a phenyl group which may be substituted with a SO ₃ M group, m represents 0 or 1, M represents an alkali metal, ammonium and A represents one of amines, A, B and C represent either a benzene ring or a naphthalene ring which may have a substituent, and B and C do not represent a naphthalene ring at the same time.)

Examples of the substituent of A, B and C in the compound of the general formula (9) include SO ₃ M group, lower alkyl group, lower alkoxy group, lower alkylcarbonylamino group, COOM group, halogen atom and the like. In addition, lower means that C1-C4. Examples of M include alkali metals, ammonium, and alkylamines which may have a substituent.

  Hereinafter, preferred specific examples of the coloring material represented by the general formulas (7) to (9) are given in the form of a free acid, but are not limited thereto. Two or more kinds of the color materials listed below may be used at the same time. Among them, it is particularly preferable to use the exemplified compound Bk3, the exemplified compound Bk4, and the exemplified compound Bk7.

  In the present invention, the ink preferably contains a blue color material and a black color material. Further, the ratio (Wbk / Wt) of the black colorant content concentration Wbk (mass%) in the ink to the total content density Wt (mass%) of all color materials in the ink is 0.04 or more and 0.5 It is preferable that it is less than. In particular, it is preferably 0.05 or more and less than 0.3. When it is less than 0.04, it becomes difficult to obtain the effect of suppressing the absorption of the entire visible light region, and when it is 0.5 or more, the color of the apparent printed product tends to be closer to black than blue.

  Furthermore, it is preferable that the maximum absorption wavelength in the wavelength region of 380 nm to 730 nm of the absorption spectrum of the black color material exists in 400 to 600 nm. The absorption spectrum of a blue-colored ink generally has an absorption in the range of 600 to 700 nm, and since the absorption in the range of 400 to 600 nm is low, the reflection spectrum in the visible light region on the printed matter is also high. By setting the position of the maximum absorption wavelength within the above range, while maintaining the apparent blue color, the reflection spectrum of the entire visible light region of the printed matter is further suppressed to a lower overall, and the barcode reader has various wavelength sensitivity characteristics. Therefore, it is possible to satisfy the readability at a higher level. Furthermore, what has a maximum absorption wavelength in 400-500 nm is preferable.

  Among the above-mentioned black color materials, those having the maximum absorption wavelength at 400 to 600 nm include C.I. I. Although food black 2 and exemplary compound Bk7 are mentioned, it is not limited to these.

  In the present invention, the ink is C.I. I. Containing Direct Blue 199, Exemplified Compound M8, and Exemplified Compound Bk7 is the most preferable combination from the viewpoint of the color tone of the postal stamp and the readability of the 2D barcode. Furthermore, as a mass ratio of these coloring materials, when the exemplified compound M8 and the exemplified compound Bk7 are both of the Na salt type, C.I. I. For direct blue 199 of 1, the colorant of exemplary compound M8 is preferably 0.3 to 0.4, and the colorant of exemplary compound Bk7 is preferably 0.1 to 0.4. In addition, C.I. I. The total content concentration of Direct Blue 199, Exemplified Compound M8 and Exemplified Compound Bk7 is preferably 1.5% by mass or more and 6.0% by mass or less, particularly 2.5% by mass or more and 4.5% by mass or less. It is preferable. When the total concentration of the coloring material is within this range, the color tone of the postal seal and the readability of the 2D barcode can be reproduced at a higher level. In addition, this combination is particularly excellent in the balance of fastness to discoloration caused by light or gas.

  Next, the aqueous medium that constitutes the ink of the present invention together with the color material will be described. The aqueous medium used in the present invention preferably contains water as a main component, and the water content in the ink is preferably 10 to 95% by mass with respect to the total mass of the ink. More preferably, it is 25-93 mass%, More preferably, it is 40-90 mass%. As the water used in the present invention, ion-exchanged water is preferable.

  In the present invention, water may be used alone as an aqueous medium, but the effect of the present invention can be made more remarkable by using water in combination with a water-soluble organic solvent.

Specific examples of the water-soluble organic solvent that can be used in the present invention are as follows.
Alkyl alcohols having 1 to 5 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, n-pentanol;
Amides such as dimethylformamide and dimethylacetamide;
Ketones or ketoalcohols such as acetone, diacetone alcohol;
Ethers such as tetrahydrofuran and dioxane;
Oxyethylene or oxypropylene addition polymers such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol;
Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, trimethylene glycol, butylene glycol, pentanediol, hexylene glycol;
Triols such as glycerin, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol;
Thiodiglycol; bishydroxyethyl sulfone; lower alkyl glycol ethers such as ethylene glycol monomethyl (or ethyl, butyl) ether, diethylene glycol monomethyl (or ethyl, butyl) ether, triethylene glycol monomethyl (or ethyl, butyl) ether;
Lower dialkyl glycol ethers such as triethylene glycol dimethyl (or ethyl) ether, tetraethylene glycol dimethyl (or ethyl) ether;
Alkanolamines such as monoethanolamine, diethanolamine, triethanolamine;
Sulfolane, N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, etc. Water-soluble organic solvents such as those described above can be used alone or as a mixture.

  The total content of these water-soluble organic solvents in the ink is preferably 50% by mass or less, particularly 5 to 40% by mass, and more preferably 10 to 30% by mass with respect to the total mass of the ink. It is preferable that

  Among these solvents, it is preferable to use ethylene glycol, diethylene glycol, triethylene glycol, 2-pyrrolidone, glycerin, polyethylene glycol, and 1,2,6-hexanetriol.

  Moreover, it is also preferable to contain urea, ethylene urea, its derivatives, trimethylolpropane, or the like as a humectant in the ink of the present invention. In particular, ethylene urea and trimethylolpropane are very suitable for the present invention. These contents are preferably 1% by mass or more, and preferably 20% by mass or less, based on the total mass of the ink.

  In the ink of the present invention, in addition to the above components, if necessary, a surfactant, an antifoaming agent, a surface tension adjusting agent, a pH adjusting agent, a viscosity adjusting agent, and an antiseptic for imparting desired performance to the ink. Additives such as antioxidants, evaporation accelerators, rust inhibitors, fungicides, and chelating agents may be blended.

As the surfactant, a nonionic surfactant may be added in order to improve the ejection property. Preferred nonionic surfactants include the following.
Polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, ethylene oxide adduct of acetylene glycol, etc. HLB is 10 or more, particularly 12 or more, and even 15 The above is preferable. These surfactants are used in an amount of 0.3% by mass or more, particularly 0.5% by mass or more, and more preferably 0.8% by mass or more with respect to the total mass of the ink in order to obtain a sufficient discharge sustaining effect. Preferably there is. Moreover, since the viscosity of an ink will become high too much when it is too much, it is 3 mass% or less with respect to the ink total mass, Especially 2.5 mass% or less, Furthermore, it is preferable that it is 2.0 mass% or less.

  The viscosity of the ink of the present invention is preferably in the range of 0.7 to 12 cP at 25 ° C. When the viscosity of the ink is within the above range, it is preferable that normal ejection can be performed in ink jet recording, and the penetration into the recording medium is quick due to the viscosity resistance, and there is no problem in terms of fixability.

  The ink of the present invention is an ink used for inkjet recording, in particular, it has excellent image characteristics such as color developability of printed images and 2D barcode readability, as well as excellent ink storage stability, dry fixability, print quality and the like. In addition, it is possible to provide an ink excellent in performance of fixing characteristics.

  The ink of the present invention configured as described above is particularly effective when used in ink jet recording. In particular, in a field where continuous printing is essential, the printability is important and more effective. As the ink jet recording method, there are a recording method in which mechanical energy is applied to ink to eject droplets and a recording method in which thermal energy is applied to ink and ink droplets are ejected by foaming of the ink. The ink of the present invention is particularly suitable.

〔recoding media〕
The recording medium in the present invention is not limited to envelopes and postcards, and any recording medium can be used as long as it can print indicia. If the recording medium is normally used as mail, the present invention can show a sufficient effect.

[Inkjet recording method]
The inkjet recording method that can be used in the present invention is not particularly limited as long as it can form an image by discharging droplets using the above-described ink. However, it is necessary to print the character information, design information, and 2D barcode information of the post stamp on the recording medium such as various envelopes having various ink absorption characteristics with high quality and at high speed. From this viewpoint, it is preferable to set the image resolution, the ejection amount, the ejection frequency, the recording conditions for recording scanning, and the surface tension of the ink to the conditions described below.

<Resolution>
The inventors of the present invention have made extensive studies on the resolution of an image that can be read as a 2D barcode image and is visible with respect to design information and character information of a postal stamp. As a result, it has been found that a resolution of 300 × 300 dpi to 600 × 600 dpi is preferable. If the resolution of the image is too low, the visibility of design information and text information necessary as an indicium may be deteriorated, and reading by a 2D barcode reader may occur. On the other hand, if the resolution of the image is too high, the character quality will be high, but the reading accuracy and mechanical processing efficiency of the 2D barcode reader will not change, so finer driving of the recording device will only lead to an increase in cost. May end up. The resolution of the image that achieves compatibility between image visibility, readability, and cost at a higher level is preferably 600 × 300 dpi.

<Applied amount (discharge amount)>
In order for the recorded 2D barcode image to have sharpness and contrast that can be identified by a 2D barcode reader, the applied amount of ink (discharge amount) is 15 ng or more per dot. It is preferable that it is 40 ng or less. When the applied amount is less than 15 ng, the area factor is not filled, and a sufficient density may not be obtained to ensure contrast. On the other hand, when the applied amount exceeds 40 ng, the area factor is buried more than necessary, and the sharpness deteriorates, so that a reading failure may occur in the 2D barcode reader.

  In addition, in the above-described image resolution, in order to further improve the contrast and sharpness, it is preferable that the applied amount per dot is 18 ng or more and 30 ng or less.

<Discharge frequency, number of scans>
As the ejection frequency of the recording head according to the present invention, when the ejection frequency is 10 kHz or more and less than 10 kHz with respect to the above-described image resolution, the recording speed is lowered, and the recording head is used for processing a large amount of mail. Is not preferred. On the other hand, the upper limit value of the ejection frequency of the recording head is preferably 40 kHz or less with respect to the above-described image resolution. When the ejection frequency exceeds 40 kHz, the durability of the recording head deteriorates, and it becomes difficult to maintain the reliability of the recording apparatus, and at the same time, it becomes difficult to realize stable ejection at a high frequency. There is a case.

  The number of scans for recording is preferably one scan from the viewpoint of recording speed.

<Ink surface tension>
The surface tension of the ink of the present invention is 35 mN / m or more at 25 ° C. in order to keep the image quality (ink bleeding) and fixability of the recorded image at the above-described image resolution, discharge amount, and discharge frequency. More preferably, it is preferably 43 mN / m or less. The inventors formed images on envelopes made of various materials under the above-described recording conditions, and examined the image quality. As a result, it has been found that when an envelope without an ink absorbing layer is used, dots are adhered to each other, which may cause significant image bleeding. As a result of further intensive studies, it was found that when the surface tension of the ink is 35 mN / m or more, the quality of the recorded image is drastically improved.

  Also, when the surface tension is greater than 43 mN / m, image bleeding is reduced satisfactorily, but on the other hand, ink tends to remain relatively on the paper surface as compared with ink having a low surface tension. Accordingly, when the recording media on which the postal indicia are printed at a high speed are stacked, the ink may not be sufficiently fixed on the recording medium after the image is formed and before the next recording medium is stacked. As a result, when the recording media are rubbed with each other, the 2D barcode image is easily degraded, and a reading failure by the 2D barcode reader may occur.

[Inkjet recording device]
Hereinafter, an embodiment of an ink jet recording apparatus of the present invention will be described with reference to the drawings. FIG. 2 is a schematic perspective view of the entire inkjet recording apparatus of the present embodiment.

  This recording apparatus is a detachable recording apparatus having a recording function, which is mounted on a main body of a printing machine that continuously records an image of a predetermined pattern on a recording medium such as an envelope or continuous paper that can be cut as needed.

  This recording apparatus is divided into the following units. First, the recording apparatus includes a recording head unit including a recording head 50 that performs recording by discharging ink. A recording unit 50 is mounted, and a carriage unit including a carriage 200 and the like that moves the recording head 50 between a recording position and a standby position is provided. In addition, an ink supply system unit 100 for supplying ink to the recording head 50, to which a detachable main tank 500 is mounted, is provided. Further, a recovery system unit 300 is provided for recovering ink ejection performance of the recording head 50 by sucking out thickened ink, dust, etc. generated in the recording head 50 together with ink near the nozzle. In addition, a control unit having a control board 107 that performs electrical control of the recording operation is provided. A power supply unit (not shown) is also provided. These units are housed and supported in a frame 106.

  The frame 106 is a box having four side surfaces and a bottom formed of sheet metal. On one side surface 102 of the frame 106, a CR shaft 104 and a CR rail 103 that slidably support the carriage 200 are assembled in parallel to each other. The carriage 200 is reciprocated in the box body along the CR rail 103 (in the front-rear direction in FIG. 2) when the driving force of the driving motor 105 is transmitted by a belt (not shown).

  The recording head 50 has two recording positions, the front end and the rear end of the reciprocating range of the carriage 200 on which the recording head 50 is mounted, and the central portion of the reciprocating movement is a recovery position by the recovery system unit 300. At a recording position (not shown), an electrical signal is sent to the recording head 50, and ink is ejected from a plurality of nozzles arranged on the head to be applied to a recording medium such as an envelope. In this recording apparatus, after the recording head 50 is reciprocated and fixed at the recording position, the recording medium is transported so as to pass directly below the nozzle portion of the recording head 50 so that the recording head 50 has a desired image resolution. The image forming is performed by controlling the ejection frequency of the recording medium and the conveyance speed of the recording medium. In the present invention, the state in which the nozzle resolution of the recording head 50 is 600 dpi and the dots are applied at 300 dpi in the transport direction is preferable in terms of image quality, ink fixing properties, and color developing properties.

  In the above-described ink jet recording apparatus, the head is fixed to the carriage. However, the recording apparatus according to the present invention is not limited to these, and the recording head is driven to the left and right during printing to perform serial printing. It may be a printer. Hereinafter, the liquid jet recording head 50 of the present invention will be described in detail.

[Recording head]
3 and 4 are perspective views showing the liquid jet recording head 50, and FIGS. 5 and 6 are exploded perspective views of the liquid jet recording head 50. As shown in these drawings, the recording head 50 is configured as a cartridge that can be detachably mounted on the carriage 2 of the ink jet recording apparatus of FIG. The recording unit (head chip) 51 shown in FIG. 5 and the recording liquid storage unit 60 shown in FIGS. The recording unit 51 and the recording liquid storage unit 60 can be detachably connected to each other. The recording liquid storage unit 60 stores ink to the recording unit 51, and the recording unit 51 forms and discharges ink droplets for recording.

  As shown in FIGS. 3 to 6, the recording unit 51 is mainly composed of the following. That is, a recording element substrate (recording element array) 52, a support substrate (support portion) 53, a plate 54, a flow path forming member (main body) 55, a porous member (filter) 56, a sheet electrical wiring substrate 57, a contact terminal wiring substrate. 58 or the like. The recording element substrate 52 has a plurality of recording elements (electrothermal conversion elements) for discharging recording liquid on one side thereof, wiring such as Al for supplying electric power to each recording element (detailed in FIG. 10 below), and Is made of a Si substrate formed by a film forming technique. In this Si substrate, a plurality of recording liquid channels and a plurality of discharge ports (all not shown) are formed with high accuracy by photolithography so as to correspond to each recording element. Further, as shown in FIG. 7, the recording element substrate 52 has recording liquid supply ports 52a for supplying the recording liquid from the recording liquid storage unit 60 to a plurality of recording liquid flow paths connected to the respective discharge ports. It is on the back side (support substrate 53 side).

  FIG. 10 is a partially broken perspective view for explaining the configuration of the first recording element substrate 52. For example, the first recording element substrate H1100 is anisotropically etched by using a Si substrate H1110 having a thickness of 0.5 to 1 mm and an ink supply port H1102 having a long groove-like through-hole serving as an ink flow path using the crystal orientation of Si. Or sandblasting. On both sides of the ink supply port H1102, the electrothermal conversion elements H1103 are arranged and arranged one by one, and an electric wiring (not shown) made of Al or the like for supplying electric power to the electrothermal conversion elements H1103. Is formed. These electrothermal conversion elements H1103 and electric wiring are formed by a film forming technique. The electrothermal conversion elements H1103 are arranged in a staggered manner in each row, that is, the positions of the discharge ports in each row are slightly shifted so as not to line up in a direction orthogonal to the row direction. Furthermore, it is preferable that the discharge amount of each nozzle is 15 ng or more and 40 ng or less because suitability for a wider range of recording media is improved. Electrode portions H1104 for supplying electric power to the electric wiring or supplying an electric signal for driving the electrothermal conversion element H1103 are arranged along both outer sides of the electrothermal conversion element H1103. Is formed. A bump H1105 made of Au or the like is formed on the electrode portion H1104.

  On the surface of the Si substrate H1110 on which these patterns are formed, a structure made of a resin material is formed by a photolithography technique. Such a structure has an ink flow path wall H1106 that forms an ink flow path corresponding to the electrothermal conversion element H1103 and a top portion that covers the top thereof, and an ejection port H1107 is opened in the ceiling. The discharge port 1107 is provided to face the electrothermal conversion element H1103, and forms a discharge port group H1108. In the first recording element H1100, the ink supplied from the ink flow path H1102 is ejected from the ejection port 1107 facing each electrothermal conversion element H1103 by the pressure of the bubbles generated by the heat generated by each electrothermal conversion element H1103. The

  In the present invention, a liquid jet recording head having a nozzle arrangement in which the ejection ports H1107 are arranged in two rows in a staggered manner at intervals of 300 dpi is a preferred embodiment. In this case, the discharge amount of each nozzle is preferably 15 to 40 ng. By adopting such a form, the degree of overlap of dots on the recording medium becomes an appropriate balance, improving the color development of the printed portion, and at the same time sufficiently high definition from the viewpoint of the readability of character information and 2D barcodes. Image formation is possible.

  The recording element substrate 52 is bonded to the support substrate 53. The support substrate 53 is made of a rigid material such as ceramic or alumina, and has a recording liquid channel 53 a for supplying ink to the recording element substrate 52. The recording liquid flow path 53a communicates with a supply port 53b (see FIG. 5) provided on the back surface side (flow path forming member 55 side) of the support substrate 53. Further, the plate 54 is fixed to the support substrate 53 with an adhesive or the like. The plate 54 has an opening 54a for avoiding interference with the recording element substrate 52, and the recording element substrate 52 is disposed in the opening 54a. The support substrate 53 is fixed to the flow path forming member 55 using a bonding means such as an adhesive or a screw.

  As shown in FIG. 5, the flow path forming member 55 has a substantially L shape, and has a recording liquid flow path (not shown) for circulating ink therein. When the support substrate 53 is fixed to the flow path forming member 55, both recording liquid flow paths communicate with each other through the supply port 53b and the like. Further, a porous member 56 is joined to the flow path forming member 55. The porous member 56 is bonded to the flow path forming member 55 from the opposite side of the support substrate 53. The porous member 56 prevents dust from entering the recording liquid from the upstream side, that is, the recording liquid storage unit 60 side.

  Further, a sheet electrical wiring board 57 is bonded to the upper surface of the plate 54 on the support substrate 53, and the sheet electrical wiring board 57 is electrically connected to each recording element of the recording element substrate 52. The sheet electrical wiring board 57 is connected to a contact terminal wiring board 58 disposed on the back surface of the flow path forming member 55 by connection means such as ACF, lead bonding, wire bonding, or a connector. A series of electrical wiring portions configured by connecting the sheet electrical wiring substrate 57 and the contact terminal wiring substrate 58 is for applying an electrical signal for discharging the recording liquid to the recording element substrate 52. .

  The contact terminal wiring board 58 has a plurality of signal input terminals 58a for receiving electrical signals from the ink jet recording apparatus side of FIG. Thereby, an electrical recording signal for image recording is given to each recording element of the recording element substrate 52 via the contact terminal wiring substrate 58 and the sheet electrical wiring substrate 57 from the main body side of the ink jet recording apparatus of FIG. It becomes possible. When an electric pulse signal serving as a recording signal is given from the ink jet recording apparatus side of FIG. 2 to each electrothermal transducer which is a recording element as described above, thermal energy is given to the recording liquid, and the phase of the recording liquid at that time The change causes firing of the recording liquid (film boiling). Due to the foaming bubble pressure, droplets are ejected from the ejection ports of the recording head 50. In the present embodiment, the electric wiring portion is composed of the sheet electric wiring board 57 and the contact terminal wiring board 58 which are separate from each other, but is not limited thereto. That is, it is also possible to use an electrical wiring member in which the sheet electrical wiring board 57 and the contact terminal wiring board 58 are integrated.

  The method for supplying the ink of the present invention to the recording head will be described. As shown in FIG. 3 and the like, the circular hole portion 66 and the joint rubber 70 are disposed at two positions above and below the back surface portion of the frame body 61. Among these, the lower circular hole 66 and the joint rubber 70 constitute a supply flow path for supplying ink from an external recording liquid storage tank (not shown) arranged in the ink jet recording apparatus of FIG. . That is, the ink of the present invention is supplied into the common liquid chamber 62 shown in FIG. At that time, the recording liquid supply needle (not shown) provided on the ink jet recording apparatus side in FIG. 2 tears the slit 71 at the center of the joint rubber in FIG. The ink of the present invention is supplied smoothly. On the other hand, the upper circular hole portion 66 and the joint rubber 70 constitute an intake passage for releasing air existing inside the common liquid chamber 62 to form a negative pressure inside the common liquid chamber 62. The internal pressure of the common liquid chamber 62 is controlled by discharging the air inside the common liquid chamber 62 to the outside from the intake passage using an intake means such as a pump. That is, the supply of the recording liquid into the common liquid chamber 62 can be controlled by increasing the negative pressure in the common liquid chamber 62 using this intake passage.

  The ink jet recording head described above supplies the ink of the present invention from the external recording liquid storage tank to the recording liquid storage unit in the recording head as appropriate. However, a head capable of ejecting the ink of the present invention can be used equally even with an integrated recording head of an ink tank and a recording unit without an external recording liquid storage tank.

  Further, although the above-described inkjet recording apparatus of FIG. 2 has been described in which only the recording head 50 capable of containing and ejecting one ink is mounted, it is not limited to this. A recording head accommodating a plurality of colors may be used as long as it can form a barcode image with a resolution of 300 × 300 dpi or more and 600 × 600 dpi or less in one scan.

Hereinafter, although it demonstrates more concretely using an Example , a reference example, and a comparative example, this invention is not limited by the following Example, unless the summary is exceeded. In the following description, “parts” and “%” are based on mass unless otherwise specified.

[Reference Example 1-2, Example 3-5, Reference Example 6 and Comparative Examples 1 to 4]
(Preparation of ink)
Predetermined amounts of the components shown in Table 2 below were added, and the total amount was adjusted to 100 parts with water. These components were mixed and dissolved with sufficient stirring. Thereafter, the ink was prepared by pressure filtration with a micro filter (manufactured by Fujifilm) having a pore size of 0.2 μm. Moreover, when the surface tension of the obtained ink was measured at 25 degreeC using the automatic surface tension measuring machine (model: CBVP-Z) by Kyowa Interface Science Co., Ltd., all were 38 mN / m.

Abbreviations in the table indicate the following compounds.
DBL199: C.I. I. Direct Blue 199
AB9: C.I. I. Acid Blue 9
AR52: C.I. I. Acid Red 52
FB2: C.I. I. Food black 2
Gly: glycerin TMP: trimethylolpropane DEG: diethylene glycol AE100: acetylenol E100 (manufactured by Kawaken Fine Chemical Co., Ltd.)
The Exemplified Compound M8 and Exemplified Compound Bk7 both used Na salt type.

  C. I. The maximum absorption wavelength of Food Black 2 at 380 to 780 nm was 585 nm, and the maximum absorption wavelength of Example Compound Bk7 was 482 nm.

Each ink of Examples , Reference Examples and Comparative Examples shown in Table 2 was accommodated in an empty tank, and each ink was evaluated. As the recording apparatus, the ink jet recording apparatus of FIG. 2 equipped with the head of FIG. 3 having an on-demand type multi-recording head that discharges ink by applying thermal energy according to the recording signal to the ink was used. As the recording medium, a commercially available white woven envelope (Georgia-Pacific, ISO whiteness 83%, steecht size degree 12 seconds) was used. Printing was performed by a method (so-called one-pass printing) in which 25 ng of ink was applied per dot under the conditions of an image resolution of 600 × 300 dpi and an ejection frequency of 15 kHz, and an image was formed by one scan.

(1) a ^* , b ^* of the printing portion, integrated value of reflection spectrum 25 ng of ink is applied to each pixel at a resolution of 600 × 300 dpi, and the amount of ink applied to the recording medium is 4.5 mg per square inch The solid portion was printed so that it was left for 24 hours after printing. The printed printing part was measured using a Spectrolino manufactured by Gretag. The measurement conditions were: observation light source: D50, observation field of view: 2 degrees, concentration: ANSI. A, white standard: Abs, filter: No, a ^* , b ^* , and reflection spectrum of the printed part were obtained. A reflection spectrum is calculated | required as reflection intensity for every 10 nm to 380-730 nm on the same measurement conditions. Based on the obtained reflection spectrum, the integrated value S of the reflection spectrum was determined by the method described above. Similarly, the integrated value S1 of the reflection spectrum of 380 to 550 nm and the integrated value S2 of the reflection spectrum of 560 to 730 nm were obtained, and S1 / S2 was calculated.
These results are shown in Table 3.

(2) Readability 100 sheets of 2D barcode (DataMatrixECC200) having a resolution of 600 × 300 dpi and a size of 2 cm × 2 cm were printed and read using a commercially available barcode reader. The ratio of those that could not be read ((number of sheets that could not be read / 100) × 100) was evaluated as the reading defect rate (%) according to the following criteria. The results are shown in Table 3.
A: The reading failure rate is less than 5%.
B: The reading defect rate is 5% or more and less than 10%.
C: The reading defect rate is 10% or more.

(3) Color tone and visibility A German post-type postal stamp pattern with a resolution of 600 × 300 dpi and a size of 4 cm × 2 cm was printed, and the color tone and visibility of the postal stamp were visually evaluated according to the following criteria. At that time, it was observed from a distance of 30 cm as a clear vision distance. The results are shown in Table 3.
Color tone A: Blue color preferable as a post stamp.
B: Although the color tone is slightly different, it can be recognized as a blue postal seal.
C: The color tone is clearly different as a postal seal.
Visibility A: The postal seal can be clearly recognized.
B: Although it is slightly thin, it can be recognized.
C: The print is so thin that it is difficult to recognize.

(4) Intermittent ejection stability 100% duty solid printing at a resolution of 600 × 300 dpi using all the nozzles of the head of FIG. 3 using the inkjet recording apparatus of FIG. 2 in an environment of temperature 15 ° C. and humidity 10%. went. Thereafter, the sample was left for 12 seconds, and only one dot was ejected again using all nozzles to print ruled lines. The formation state of the ruled line dots was determined according to the following criteria. The results are shown in Table 3.
A: The ruled line is not broken at all.
B: Although the dots are small, ruled lines can be formed.
C: There is a portion where the ruled lines are faintly formed.

From the results of Table 3, Example 1-2, Example 3-5, the ink of Reference Example 6, it is seen that 2D barcode reading property or color, preferably the image forming in terms of visibility have been made. Further, the inks of Reference Examples 1 and 2 and Examples 3 to 5 had good intermittent ejection stability.

[ Reference Examples 7 to 9, Examples 10 to 11, Reference Example 12 and Comparative Examples 5 to 9]
(Preparation of ink)
Predetermined amounts of the components shown in Table 4 below were added, and the total amount was adjusted to 100 parts with water. These components were mixed and dissolved with sufficient stirring. Thereafter, the ink was prepared by pressure filtration with a micro filter (manufactured by Fujifilm) having a pore size of 0.2 μm. Moreover, when the surface tension of the obtained ink was measured at 25 degreeC using the automatic surface tension measuring machine (model: CBVP-Z) by Kyowa Interface Science Co., Ltd., all were 38 mN / m.

Abbreviations in the table indicate the following compounds.
DBL199: C.I. I. Direct Blue 199
AB9: C.I. I. Acid Blue 9
AR52: C.I. I. Acid Red 52
FB2: C.I. I. Food black 2
Gly: glycerin EG: ethylene glycol DEG: diethylene glycol AE100: acetylenol E100 (manufactured by Kawaken Fine Chemical Co., Ltd.)
Exemplified Compound M8, Exemplified Compound Bk4, and Exemplified Compound Bk7 all used Na salt type.

  C. I. The maximum absorption wavelength of Food Black 2 at 380 to 780 nm was 585 nm, the maximum absorption wavelength of Exemplified Compound Bk4 was 656 nm, and the maximum absorption wavelength of Exemplified Compound Bk7 was 482 nm.

Each of the inks of Examples , Reference Examples and Comparative Examples shown in Table 4 were accommodated in an empty tank, and each ink was evaluated. As the recording apparatus, the ink jet recording apparatus of FIG. 2 equipped with the head of FIG. 3 having an on-demand type multi-recording head that discharges ink by applying thermal energy according to the recording signal to the ink was used. As the recording medium, a commercially available white woven envelope (Georgia-Pacific, ISO whiteness 83%, steecht size degree 12 seconds) was used. Printing was performed by a method (so-called one-pass printing) in which 25 ng of ink was applied per dot under the conditions of an image resolution of 600 × 300 dpi and an ejection frequency of 15 kHz, and an image was formed by one scan.

(1) a ^* , b ^* of the printing portion, integrated value of reflection spectrum 25 ng of ink is applied to each pixel at a resolution of 600 × 300 dpi, and the amount of ink applied to the recording medium is 4.5 mg per square inch The solid portion was printed so that it was left for 24 hours after printing. The printed printing part was measured using a Spectrolino manufactured by Gretag. The measurement conditions were: observation light source: D50, observation field of view: 2 degrees, concentration: ANSI. A, white standard: Abs, filter: No, a ^* , b ^* , and reflection spectrum of the printed part were obtained. The reflection spectrum is obtained as the reflection intensity every 10 nm from 380 to 730 nm under the same measurement conditions. Based on the obtained reflection spectrum, the integrated value S of the reflection spectrum was determined by the method described above. Similarly, the integrated value S1 of the reflection spectrum of 380 to 550 nm and the integrated value S2 of the reflection spectrum of 560 to 730 nm were obtained, and S1 / S2 was calculated.
These results are shown in Table 5.

(2) Readability 100 sheets of 2D barcode (DataMatrixECC200) having a resolution of 600 × 300 dpi and a size of 2 cm × 2 cm were printed and read using a commercially available barcode reader. The ratio of those that could not be read ((number of sheets that could not be read / 100) × 100) was evaluated as the reading defect rate (%) according to the following criteria. The results are shown in Table 5.
A: The reading failure rate is less than 5%.
B: The reading defect rate is 5% or more and less than 10%.
C: The reading defect rate is 10% or more.

(3) Color tone and visibility A German post-type postal stamp pattern with a resolution of 600 × 300 dpi and a size of 4 cm × 2 cm was printed, and the color tone and visibility of the postal stamp were visually evaluated according to the following criteria. At that time, it was observed from a distance of 30 cm as a clear vision distance. The results are shown in Table 5.
Color tone A: Blue color preferable as a post stamp.
B: Although the color tone is slightly different, it can be recognized as a blue postal seal.
C: The color tone is clearly different as a postal seal.
Visibility A: The postal seal can be clearly recognized.
B: Although it is slightly thin, it can be recognized.
C: The print is so thin that it is difficult to recognize.

From the results of Table 5, it can be seen that in the inks of Reference Examples 7 to 9, Examples 10 to 11, and Reference Example 12, preferable image formation is achieved in terms of 2D barcode readability, color tone, and visibility.

(Examples 13 to 34)
Predetermined amounts of the components listed in Table 6 below were added, and the total amount was adjusted to 100 parts with water. These components were mixed and dissolved with sufficient stirring. Thereafter, the ink was prepared by pressure filtration with a micro filter (manufactured by Fuji Film) having a pore size of 0.2 μm. Further, the surface tension of the obtained ink was measured at 25 ° C. using an automatic surface tension measuring machine (model: CBVP-Z) manufactured by Kyowa Interface Science Co., Ltd., and it was 38 mN / m.

Further, when the obtained ink was used to determine the a ^* and b ^* and the integrated value (S1 and S1 / S2) of the reflection spectrum of the printed portion in the same manner as in Reference Example 1, a ^* , b ^* and 4 and -30, respectively, S1 was 65, and S1 / S2 was 1.4.

Further, only acetylenol E100, which is a constituent component of ink A, and water were adjusted to obtain inks B to E having surface tension values shown in Table 7. Using these inks, the a ^* , b ^* and reflection spectrum integrated values (S1 and S1 / S2) of the printed portion were obtained in the same manner as in Reference Example 1, and a ^* , b ^* and 4 were 4 and At -30, S1 was 65 and S1 / S2 was 1.4.

  Each ink described in Tables 6 and 7 was accommodated in an empty tank, and each ink was evaluated. As the recording apparatus, the ink jet recording apparatus of FIG. 2 equipped with the head of FIG. 3 having an on-demand type multi-recording head that discharges ink by applying thermal energy according to the recording signal to the ink was used. Table 8 shows the conditions of ink, image resolution, ejection amount, ejection frequency, and number of recording scans.

<Visibility>
Visibility is easily influenced by the image resolution and the discharge amount. That is, if the image resolution and the discharge amount are low, the postal stamp pattern, character information, and the like are likely to be difficult to visually recognize. On the other hand, when the discharge amount is high, the overlap between the ink dots increases, and the visibility tends to deteriorate. The visibility experiment method is described below.

A Deutsche Post type postal stamp pattern having a size of 4 cm × 2 cm was printed, and the visibility of the postal stamp was visually evaluated according to the following criteria. At that time, it was observed from a distance of 30 cm as a clear vision distance. The results are shown in Table 9. In addition, as a recording medium, a Pergamine hull transparent envelope and a weiss (white) envelope manufactured by Zanders were used. This envelope does not have an ink absorbing layer and has poor ink absorbability.
A: The postal seal can be clearly recognized.
B: Although it is slightly thin, it can be recognized.
C: The print is so thin that it is difficult to recognize.

<Readability>
Readability is greatly affected by image resolution, ejection amount, and ink surface tension. That is, when the image resolution is low and the discharge amount is small, the area factor is not filled and it is difficult to obtain sufficient contrast necessary for distinguishing the bright part and the dark part of the 2D barcode. Also, if the ejection amount is large, sufficient sharpness is difficult to obtain due to the overlapping of ink dots. In addition, when the surface tension of the ink is low, ink mist and image bleeding tend to occur, and it is difficult to obtain sharpness. Therefore, in any case, the readability by the 2D barcode reader is likely to deteriorate. The readability experiment method is described below.

100 sheets of 2D barcode (DataMatrix ECC200) having a size of 2 cm × 2 cm were printed and read using a commercially available barcode reader. The ratio of those that could not be read ((number of sheets that could not be read / 100) × 100) was evaluated as the reading defect rate (%) according to the following criteria. The results are shown in Table 9. As the recording medium, the above-mentioned Pergamine hull transparent envelope, weiss (white) manufactured by Zanders was used. Furthermore, in this test, the reading test was performed after storing for 5 minutes under the condition that the recorded envelopes did not overlap.
A: The reading failure rate is less than 5%.
B: The reading defect rate is 5% or more and less than 10%.
C: The reading defect rate is 10% or more.

<Recording speed>
The recording speed is easily influenced by the ejection frequency and the number of recording scans. That is, when the ejection frequency is low at a certain resolution, the recording speed is reduced in proportion thereto. Further, if the number of recording scans is two or more, it is simply twice or more compared to one scan. The recording speed experiment method is described below.

A 4cm x 2cm Deutsche Post-type post stamp pattern is printed on a commercially available white woven envelope (Georgia-Pacific, ISO whiteness 83%, steecht size 12 seconds). Was measured. Evaluation was performed according to the following criteria. The results are shown in Table 9.
A: 280 sheets or more per minute.
C: Less than 280 sheets per minute.

<Print durability>
Printing durability is easily affected by image resolution and ejection frequency. That is, if the image resolution and the ejection frequency are high, the number of times the heater is used when recording on the same number of envelopes increases, and there is a concern that ejection failure may occur due to scraping of the heater protective film, disconnection, kogation, or the like. The printing durability test method is described below.

After 50,000 sheets of a 4cm x 2cm Deutsche Post postal stamp pattern are printed on a commercially available white woven envelope (Georgia-Pacific, ISO whiteness 83%, steecht size 12 seconds), nozzle check A pattern was printed. Evaluation was performed according to the following criteria. The results are shown in Table 9.
A: There is no discharge or twisting.
B: Undischarge, twist, etc. were confirmed to some extent.
C: There are many non-discharges, twists, etc.

<Readability after loading>
The readability after loading is easily affected by the surface tension of the ink. That is, if the surface tension of the ink is too high, the relative fixability is likely to deteriorate, and the recording media are rubbed with each other, so that the quality of the 2D barcode image is lowered and the readability is easily deteriorated. The experimental method for readability after loading is described below. Note that, when the readability is poor when not loaded, the readability is poor even when loaded, regardless of the fixability.

Print 2 sheets of 2D barcode (DataMatrixECC200) with a size of 2 cm × 2 cm on a commercially available white woven envelope (Georgia-Pacific, ISO whiteness 83%, Steecht size 12 seconds). Stored to be loaded. Thereafter, a reading test was performed using a commercially available bar code reader, and the ratio of those that could not be read ((number of sheets that could not be read / 100) × 100) was evaluated as a reading defect rate (%). Evaluation was performed according to the following criteria. The results are shown in Table 9.
A: The reading failure rate is less than 5%.
B: The reading defect rate is 5% or more and less than 10%.
C: The reading defect rate is 10% or more.

  From the results in Table 9, it can be seen that in Examples 13 to 27, visibility, readability, recording speed, printing durability, and readability after loading are compatible at a high level.

(Examples 35-39)
As described above, the generation of ink mist is easily affected by the surface tension of the ink. Therefore, in Examples 35 to 39, the recording conditions other than the surface tension of the ink were made the same, and the generation of ink mist due to the surface tension of the ink was compared. The ink mist experiment is described below.

The inks A to E are mounted on the recording apparatus shown in FIG. 2, and a German post-type postal stamp pattern is commercially available under the conditions shown in Table 10 below (a white woven envelope made by Georgia-Pacific, ISO whiteness 83%; 50,000 sheets were printed at a sizing degree of 12 seconds), and adhesion of ink mist inside the main body was observed after printing. Evaluation was performed according to the following criteria. The results are shown in Table 11.
A: There is no or very little stain due to ink mist.
B: Dirt due to ink mist is small.
C: There are many stains due to ink mist.

  From the results of Table 11, it can be seen that the surface tension of the ink can affect the ink mist, and that the surface tension of the ink is 35 mN / m or more, it is preferable in terms of improving the readability of the 2D barcode. .

It is a figure for demonstrating the method of calculating the integrated value of the reflection spectrum of the printing part by the ink of this invention. 1 is a schematic perspective view of an ink jet recording apparatus of the present invention. 1 is a perspective view showing a first embodiment of a liquid jet recording head according to the present invention. 1 is a perspective view showing a first embodiment of a liquid jet recording head according to the present invention. FIG. 5 is an exploded perspective view illustrating the liquid jet recording head of FIGS. 3 and 4. FIG. 5 is an exploded perspective view illustrating the liquid jet recording head of FIGS. 3 and 4. FIG. 5 is an enlarged perspective view illustrating a main part of the liquid jet recording head of FIGS. 3 and 4. FIG. 5 is a perspective view showing a recording liquid storage unit constituting the liquid jet recording head of FIGS. 3 and 4. It is an expansion perspective view which shows the joint rubber with which a recording liquid storage unit is equipped. FIG. 3 is a perspective view in which a recording element substrate is partially broken.

Claims (15)

A mailing ink used for inkjet recording,
In ^{a *} is -10 to 15 in the CIE ^L * ^a * ^{b *} color system of the printing unit which is obtained by the ink amount of ink applied applied to the recording medium such that per square inch 4.5mg , ^{b *} is -50 or more -15 or less, and an integrated value of the reflection spectrum at 380nm or 730nm or less in a wavelength range of the indicia shaped portion is Ri der 90 or less,
The ink contains a plurality of color materials, and the plurality of color materials are C.I. I. Direct Blue 199, Exemplified Compound M8 below and Exemplified Compound Bk7 below, C.I. I. The ratio of Direct Blue 199, Exemplified Compound M8 below and Exemplified Compound Bk7 below (CI Direct Blue 199: Exemplified Compound M8: Exemplified Compound Bk7) is from 1: 0.3 to 0.4: 0.1 on a mass basis. ink mailing, wherein 0.4 der Rukoto.

(In the above formula, M represents either an alkali metal or ammonium.)

(In the above formula, M represents at least one selected from alkali metals, ammonium and alkylamine.) The mailing ink according to claim 1, wherein each of the exemplified compound M8 and the exemplified compound Bk7 is a Na salt type. Wherein ^{a *} is 0 to 10 in the CIE ^L * ^a * ^{b *} color system of the printing unit, mailing ink according to claim 1 or 2 ^{b *} is -40 or more -15 or less. The mailing ink according to any one of claims 1 to 3, wherein the integrated value of the reflection spectrum in the wavelength region of 380 nm or more and 730 nm or less of the printing unit is 80 or less. The mailing ink according to any one of claims 1 to 4 , wherein an integrated value of reflection spectra in a wavelength range of 380 nm to 730 nm of the printing unit is 30 or more. The ratio (S1 / S2) of the integrated value S1 of the reflection spectrum in the wavelength region of 380 nm to 550 nm and the integrated value S2 of the reflection spectrum in the wavelength region of 560 nm to 730 nm of the printing unit is 1.2 or more. The mailing ink according to any one of 1 to 5 . The ratio (S1 / S2) between the integrated value S1 of the reflection spectrum in the wavelength region of 380 nm to 550 nm and the integrated value S2 of the reflection spectrum in the wavelength region of 560 nm to 730 nm is 3.0 or less. The mailing ink according to any one of 1 to 6 . The mailing ink according to any one of claims 1 to 7 , wherein the ink contains at least a blue color material and a black color material as color materials. The ratio (Wbk / Wt) of the content concentration Wbk (mass%) in the ink of the black color material to the total content concentration Wt (mass%) of all the color materials in the ink is 0.04 or more and less than 0.5. The mailing ink according to claim 8 . The mailing ink according to any one of claims 1 to 9 , wherein the ink has a surface tension of 35 mN / m or more. An ink tank containing a mailing ink used for inkjet recording,
In ^{a *} is -10 to 15 in the CIE ^L * ^a * ^{b *} color system of the printing unit which is obtained by the ink amount of ink applied applied to the recording medium such that per square inch 4.5mg , ^{b *} is -50 or more -15 or less, and an integrated value of the reflection spectrum at 380nm or 730nm or less in a wavelength range of the indicia shaped portion is Ri der 90 or less,
The ink contains a plurality of color materials, and the plurality of color materials are C.I. I. Direct Blue 199, Exemplified Compound M8 below and Exemplified Compound Bk7 below, C.I. I. The ratio of Direct Blue 199, Exemplified Compound M8 below and Exemplified Compound Bk7 below (CI Direct Blue 199: Exemplified Compound M8: Exemplified Compound Bk7) is from 1: 0.3 to 0.4: 0.1 on a mass basis. an ink tank for mailing, wherein 0.4 der Rukoto.

(In the above formula, M represents either an alkali metal or ammonium.)

(In the above formula, M represents at least one selected from alkali metals, ammonium and alkylamine.) An ink jet recording method for mailing that performs ink jet recording using a mailing ink,
15 ^{a *} is -10 or more color printing unit which is obtained in the CIE ^L * ^a * ^{b *} color system by the ink amount of ink applied applied to the recording medium such that per square inch 4.5mg hereinafter, ^{b *} is -50 or more -15 or less, and an integrated value of the reflection spectrum at 380nm or 730nm or less in a wavelength range of the indicia shaped portion is Ri der 90 or less,
The ink contains a plurality of color materials, and the plurality of color materials are C.I. I. Direct Blue 199, Exemplified Compound M8 below and Exemplified Compound Bk7 below, C.I. I. The ratio of Direct Blue 199, Exemplified Compound M8 below and Exemplified Compound Bk7 below (CI Direct Blue 199: Exemplified Compound M8: Exemplified Compound Bk7) is from 1: 0.3 to 0.4: 0.1 on a mass basis. mailing inkjet recording method comprising 0.4 der Rukoto.

(In the above formula, M represents either an alkali metal or ammonium.)

(In the above formula, M represents at least one selected from alkali metals, ammonium and alkylamine.)   The inkjet recording method for mailing according to claim 12, wherein the resolution in the inkjet recording is 300 × 300 dots or more and 600 × 600 dots or less per square inch, and recording is performed in one scan.   14. The mailing inkjet recording method according to claim 12, wherein an ink application amount in the inkjet recording is 15 ng or more and 40 ng per dot.   The mailing inkjet recording method according to any one of claims 12 to 14, wherein an ejection frequency in the inkjet recording is 10 kHz or more.