JPH02232273A - Ink and recording method - Google Patents

Abstract

PURPOSE:To obtain an ink providing a printed image causing neither browning nor greening on a coated paper by compounding two specified water-soluble dyes, a water-soluble org. solvent and water. CONSTITUTION:In an ink contg. water-soluble dyes, a water-soluble org. solvent and water, at least dyes of formulas I and II are incorporated as said dyes. In the formulas, X1-X6 are each lithium, sodium, potassium or a quat. ammonium compd.; Q1 and Q2 are each a phenyl or naphthalene ring which may has a substituent. As the compd. of formula I, dyes of formula III, formula IV, etc., can be cited. As the compd. of formula II, C.I. Direct Black 19, C.I. Acid Green 20, a dye of formula V, etc., can be cited. The mixing ratio of the dye of I to the dye of II is in the range of 5:1-1:5 by wt. The total wt. of the dyes of formulas I and II in said ink is usually 0.1-15wt.% of the total wt. of the ink.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an ink and a recording method using the ink, and more particularly to an aqueous ink that provides a black image with improved indoor discoloration properties and outdoor discoloration properties. The present invention relates to an ink and a recording method using the ink, particularly an inkjet recording method.

(Prior Art) Conventionally, water-based inks in which water-soluble dyes are dissolved in an aqueous medium have been used as inks for fountain pens, felt pens, etc., and inks for inkjet recording. A water-soluble organic solvent is generally added to prevent the ink from clogging the ejection nozzle.

These conventional inks must provide an image with sufficient density, do not clog the pen tip or nozzle, dry well on the recording material, have little bleeding, and have storage stability. In particular, in inkjet systems that utilize thermal energy, it is required to have excellent heat resistance, and images formed are also required to have sufficient light resistance, water resistance, etc.

Also, inks of various hues are prepared from dyes of various hues, among which black ink is the most important ink used for both monochrome and full color images. Conventionally, dyes for these black inks have mainly been c. r. Food Black 2 has been used (Japanese Patent Application Laid-Open Nos. 59-93766 and 59-9)
(See Publication No. 3768).

(Problems to be Solved by the Invention) Among the various required performances mentioned above, the light resistance of the image formed is particularly important.

In the past, the problem with the light resistance of images was mainly fading due to direct sunlight and various types of illumination light.These fading problems have been solved by selecting dyes with excellent light resistance. ．． I. Food Black 2 is known as a dye with excellent light resistance, and as a further improvement on this, JP-A-6
No. 2-39676, No. 62-252465 and No. 62
Dyes (dyes represented by the general formula (A) in @) described in Japanese Patent Application No. 199667 and Japanese Patent Application No. 184743/1988 have been proposed.

However, recently, in addition to these fading problems, the problem of image discoloration has also been brought into focus. In other words, images made with conventional ink suffer from not only fading but also discoloration. Discoloration does not change much in density, but changes in hue. Particularly in black ink, which is the most commonly used ink, The problem of brown discoloration, in which black changes to brown, is an important problem, and especially in the case of full-color images, image quality rapidly deteriorates due to this brown discoloration.

This brown discoloration problem progresses even indoors where there is no direct sunlight, and the discoloration is also accelerated by the type of recording material used to form the image. 1. In Food Black 2, this problem of brown color was unavoidable.

In particular, in the case of so-called coated paper, in which an ink-receiving layer containing a pigment and a binder is formed on a base layer of paper, etc., in order to improve image quality such as color development, clarity, and resolution of the ink,
In the case of plain paper, even ink with little problem of discoloration causes significant brown discoloration, and this problem cannot be solved simply by selecting a dye with good light fastness.

For this reason, the method shown in the specification of Japanese Patent Application No. 184743/1983 has attempted to improve the brown discoloration, and it has become possible to improve the brown discoloration, but the printed matter obtained by the method according to the above specification However, when printed materials are posted outside where there is no direct sunlight, there may be a phenomenon in which the black color fades to dark green to light green (conversion), and this problem of greening cannot be solved with conventional methods. It was impossible.

Therefore, an object of the present invention is to provide an ink and a recording method that can satisfy the general performance requirements as described above, and can also provide images on coated paper that do not cause problems of brown discoloration or green discoloration. be.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides an ink containing a water-soluble dye, a water-soluble organic solvent, and water, in which the dye contains at least a dye represented by the following general formula (A) and a dye represented by the following general formula (B). The present invention relates to an ink characterized by containing the following: and a recording method using the ink.

(In the above general formulas A and B, X, to x8 represent one type or a mixture of lithium, sodium, potassium and quaternary ammonium compounds, and Q1 or Q2 is a phenyl ring or naphthalene ring which may have a substituent. ) (Function) By selecting and using a dye with a specific molecular structure as the ink dye, there is little indoor discoloration, that is, brown discoloration, even on coated paper, and there is no risk of discoloration when exposed to direct sunlight. A black ink is provided that provides images with less outdoor discoloration, ie, less greening.

Further, in the second aspect of the present invention, it is possible to provide a black image with less browning and greening on coated paper using the above ink.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The dye used in the ink of the present invention has the general formula (A
) (hereinafter referred to as A dye) and the general formula (B
) (hereinafter referred to as B dye).

In dye A, the cations of X to x4 are lithium (Lj),
It is a dye that is one or a mixture of two or more of sodium (Na), potassium (κ), or quaternary ammonium compounds, and is dark green ~ #1'! It indicates green color.

On the other hand, in dye B, the cation is one or a mixture of two or more of lithium, sodium, potassium, or quaternary ammonium compounds, and dye B does not necessarily have to be a single compound, but one that satisfies general formula (B). If so, a mixture of two or more types may be used.

Dye A is a dye that has good water resistance and light resistance against direct sunlight, but it has the disadvantage that if recorded images printed on coated paper are left indoors, the prints will turn brown in about 4 to 90 days. have.

In addition, if recorded images printed on coated paper or plain paper are not exposed to direct sunlight but are left outdoors with heavy traffic (presumably containing a lot of nitrogen oxides and sulfur oxides), they will last for up to 10 days. The disadvantage is that the printed characters fade to pale green after about 90 days.

On the other hand, dye B is a boriazo dye that is higher than disazo and contains a salt of 8-amino-1-naphthol disulfonic acid such as H acid or K acid in its molecular structure, and dye B has a color ranging from dark green to dark purple depending on its structure. In general, its water resistance and light resistance to direct sunlight are at the same level or lower than A dye, but it is so good that green and brown discoloration is virtually no problem. It is something.

The present invention is characterized by using A dye and B dye together, but if a desired color tone cannot be obtained by the combination of A dye and B dye, other toning dyes may be used in combination. However, there is no problem at all.

Specific examples of the dyes of general formulas (A) and (B) include the following dyes, but are not limited to these dyes.

[Specific examples of dyes of general formula (A)] (M is a mixture of Li:K=3:1) [Specific examples of dyes of general formula (B)] B-I C. I. Direct black 19B-2
C. I. Direct Black 154B-3 C. I.
Direct Black 166B-4 G. I. Acid Blue-29B-5 C. I. acid green 19
B-6 C. I. Acid Green 20B-7
C. I. Acid Black 1 The amounts of the above A dye and B dye to be used may be any amount as long as the purpose of the present invention is achieved and are not particularly limited, but the mixing ratio of A dye and B dye is 5:1 to 1: by weight. The range is 5.

The total amount of dyes A and B used in the ink of the present invention is not particularly limited, but is generally 0.1 to 15% by weight, preferably 0.3% by weight of the total weight of the ink.
The amount accounts for 10 to 10% by weight, more preferably 1.5 to 6% by weight.

The aqueous medium suitable for use in the ink of the present invention is water or a mixed solvent of water and a water-soluble organic solvent, and particularly preferred is a mixed solvent of water and a water-soluble organic solvent, It contains a polyhydric alcohol, which has the effect of preventing ink from drying, as a water-soluble organic solvent. Further, as water, it is preferable to use deionized water rather than ordinary water containing various ions.

Examples of water-soluble organic solvents used in combination with water include methyl alcohol, ethyl alcohol, n-propyl alcohol, isobropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol. , alkyl alcohols having 1 to 5 carbon atoms such as n-pentanol; amides such as formamide, dimethylformamide, and dimethylacetamide; ketones or keto alcohols such as acetone, 2-butanone, and diacetone alcohol; tetrahydrofuran; Ethers such as dioxane: polyalkylene glycols such as polyethylene glycol and polybrobylene glycol; ethylene glycol, propylene glycol, trimethylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, Alkylene glycols in which the alkylene group has 2 to 6 carbon atoms such as thiodiglycol, hexylene glycol, diethylene glycol; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol 1,000 methyl (or ethyl) ether, triethylene Lower alkyl ethers of polyhydric alcohols such as glycol monomethyl (or ethyl) ether; triethylene glycol dimethyl or ethyl
Lower dialkyl ethers of polyhydric alcohols such as ether and tetraethylene glycol dimethyl (or ethyl) ether; sulfolane, N-methyl-2-pyrrolidone,
Examples include 1,3-dimethyl-2-imidazolidinone.

An appropriate organic solvent is selected and used from the above organic solvents, but glycerin or polyethylene oxide with a degree of polymerization of 3 to 6 are particularly good for preventing ink clogging, and nitrogen-containing cyclic A compound or an ether compound of polyalkylene oxide is preferable, and lower alcohols and surfactants are preferably used for frequency response. Therefore, a preferable solvent composition in the present invention is a composition containing the various components described above in addition to water.

The content of the water-soluble organic solvent in the ink is generally 2 to 80% by weight, preferably 3 to 50% by weight of the total weight of the ink.
% by weight, more preferably in the range of 4 to 40% by weight.

In addition, the water used accounts for 45% or more, preferably 60% or more by weight of the entire ink. If the amount of water is small, a large amount of low-volatile organic solvent will remain in the formed image, and the dye will not be absorbed. This is not preferable because problems such as migration and image blurring occur.

In addition to the above-mentioned components, the ink of the present invention may optionally contain:
It may include pHll adjusters, viscosity modifiers, surface tension modifiers, and the like. Examples of the pH adjuster used in the above ink include various organic amines such as diethanolamine and triethanolamine, alkali metal hydroxides such as sodium hydroxide, lithium hydroxide, and potassium hydroxide;
Examples include inorganic alkaline agents such as sodium borate, organic acid salts such as lithium acetate, organic acids, and mineral acids.

The ink of the present invention as described above has a viscosity of 1 at 25°C.
20 cP to 20 cP, preferably 1 to 10 cP, and a surface tension of 40 dyne/c+++ or more, preferably 50 cP
It is preferable to have physical properties of dyne/cm or more and a pH of about 4 to 10.

The recording method of the present invention is a recording method characterized by using the above-mentioned ink, and the recording method and the recording material are not particularly limited. A method using paper is particularly effective.

The inkjet method may be any conventionally known method and is not particularly limited, but in the present invention, for example, the method described in Japanese Patent Application Laid-Open No. 54-59936 is used, in which the ink is rapidly heated by the action of thermal energy. Particularly useful is a method in which a volume change is caused, and ink is ejected from a nozzle by the force exerted by this state change.

That is, with this method, in the case of conventional ink, there was a risk that foreign matter would settle on the heat-generating head in the device, causing problems such as ink failure to eject, but the ink of the present invention is free from such foreign matter. Stable recording is possible because no deposits occur.

The recording material used in the present invention can be any recording material such as general plain paper, high-quality paper, coated paper, plastic film for OHP, etc., but especially when coated paper is used. A remarkable effect is produced.

These coated papers are based on paper such as plain paper or high-quality paper, and have an ink-receiving layer that serves as a pigment and binder on the surface to improve color development, clarity, dot shape, etc. with ink. That is.

In the case of these coated papers, fine pigments such as synthetic silica with a BET specific surface area of 35 to 650 rn''/g are used as pigments to produce images with excellent color development and clarity, but conventional inks Although the theoretical reason for this problem is unknown, images using black ink are particularly prone to discoloration over time, and this is a major problem not only for black monochrome images but also for full color images. .

Also, similar to these coated papers, recording materials that have a thin layer of pigment and binder on a paper base material, and in which the fibers of the base paper are mixed, can also cause similar problems. There is.

It has been found that even when a black monochrome image or a full color image is formed using the ink of the present invention on the coated paper as described above, the problem of brown discoloration as described above does not occur. Therefore, according to the method of the present invention, the BET specific surface area is 35 to 6.
Recording that does not cause discoloration indoors for a long period of time using not only coated paper using a pigment of 50 rn'/g, but also coated paper using a pigment with a BET specific surface area of less than that, as well as stamp paper and other arbitrary recording materials. Images can be provided.

Furthermore, C.I., which is conventionally known for coated paper and plain paper. I
．． After recording an image with Food Black 2 or an ink using only the dye represented by the general formula (A) of the present invention, the recorded image is not exposed to direct sunlight (therefore, conventional lightfastness evaluation cannot be performed). If posted outdoors with heavy traffic,
A phenomenon in which a black recorded image fades to a dark edge color to light green after about 10 to 90 days (margin discoloration) was observed, and this often became a problem especially in the case of full-color recorded images.

However, it has been found that when monochrome recording or full color recording is performed using the ink of the present invention, the green discoloration described above does not occur even if the poster is displayed outdoors for about 90 days.

It is clear from the above that if the ink and recording method of the present invention are used to produce green, the brown discoloration and green discoloration of black images, which have been problems in the past, can be significantly improved. Various recording materials such as these are known and have been proposed by the applicant and others, and any of these recording methods and recording materials can be used as they are in the present invention.

(Example) Next, the wooden invention will be explained in more detail by giving examples, comparative examples, and usage examples. It should be noted that unless otherwise specified, the terms in the text or % are based on weight.

Example 1 (Ink-1) Dye of Specific Example A-1 2.0 parts Dye of Specific Example B-9 0.8 parts Polyethylene glycol 200 10.0 parts Diethylene glycol
22.0 parts N-methyl-2-pyrrolidone
3.0 parts Sodium hydroxide 0.
1 part water 62
．． 0 parts After thoroughly dissolving the above ingredients by mixing and stirring while keeping them at 30 to 35°C, the pore size is 0.22 μm.
Pressure filtration was performed using a fluororesin membrane filter to obtain Ink 1 of the present invention.

Examples 2 to 5 Inks 2 to 5 comprising the following components were obtained in the same manner as in Example 1.

Length 1- (Ink 2) 1.7 parts of the dye of Example A-2 0.0 parts of the dye of Example B-7. 881S diethylene glycol 25.0 parts glycerin
8.0 parts Sodium borate (pHg moderator)
0. i part water
65.0 parts Ink-3 Dye of Specific Example A-3 1.8 parts Dye of Specific Example A-2 0 4 parts Specific Example B-8
dye 0.4 parts diethylene glycol
5.0 parts thiodiglycol
5.0 parts ethanol 3.0
Antifungal agent (Bloxel CRL (commercial eX), T(;I
) 0.05 parts Water 85.0 parts Ink-4 Dye of Specific Example A-1 1.0 parts Dye of Specific Example A-2 1.0 parts Specific Example B-2
Dye 0.5 part diethylene glycol
30.0 parts sodium hydroxide (10% aqueous K)
0.4 part water
67.5 parts Fire rattan example 1 (ink-5) 2.0 parts of the dye of the above specific example A-3 1.0 parts of the dye of the above specific example B-4 The above specific example B-7
Dye 1.0 part diethylene glycol
40.0 parts triethylene glycol
5.0 parts triethanolamine 0.
1 part water 51
．． Inks 6 to 10 of Comparative Examples were obtained in the same manner as in Example 1 using a 0 part ratio of 7 and 102 pi.

Lematsu Reiyu (Ink-6) All of the dyes in the ink of Example 1 were replaced with dye 2 of Example A-1,
Exactly the same composition except that 8 parts were substituted.

Ink 7 All of the dyes in the ink of Example 2 were replaced with the dyes of Example B-7.
Exactly the same silk composition except that 5 parts were substituted.

All of the dyes in the ink of Example 3 were C. I. Exactly the same composition except that 2.6 parts of Food Black 2 was substituted.

Example A (Ink 9) All of the dyes in the ink of Example 4 were replaced with dyes 1 and 1 of Example A-1.
The composition is exactly the same except that 1.5 parts of the dye of A-2 and A-2 were substituted with 1.5 parts of the dye.

Soft Example J (Ink-10) All the dyes in the ink of Example 5 were replaced with the dyes of Example A-3.
Exactly the same composition except that 0 part was substituted.

Usage Examples The inks of Examples 1 to 5 and Comparative Examples 1 to 5 were loaded into an inkjet printer and printed, and the resulting recorded images were evaluated. Printing conditions are shown in Usage Examples 1 to 5.

Also, the evaluation results are shown in Table 1.

Usage Example 1 Example 1 and Comparative Example using partially modified inkjet printer BJ-80A manufactured by Canon ■! Equipped with the inks shown in (Inter 1 and Ink 6), a test pattern was printed using BJ-80A inkjet printer paper (coated paper, manufactured by Canon ■) as a recording material, and the evaluation method and evaluation criteria described later were carried out. Evaluation was performed using the methods shown in T and T4.

Usage Example 2 An inkjet printer BJ-8OA manufactured by Canon ■ was partially modified and equipped with the inks (Ink-2 and Ink-7) shown in Example 2 and Comparative Example 2, and coated paper for inkjet was used as a recording material. A test pattern was printed using NM (trade name: manufactured by Mitsubishi Paper Corporation), and evaluation was performed in the same manner as in Use Example 1.

Usage Example 3 A partially modified inkjet printer BJ-130 manufactured by Canon ■ is equipped with the inks (Ink-3 and Ink-8) shown in Example 3 and Comparative Example 3, and copy paper Xerox 4024DP is used as the recording material. (Trademark: US Xe
A test pattern was printed using uncoated paper (manufactured by Rox Corp.), and evaluation was performed in the same manner as in Use Example 1.

Usage Example 4 A Canon Color Bubble Jet Covia 1 (trade name), an inkjet copying machine manufactured by Canon ■, was partially modified, and the inks shown in Example 4 and Comparative Example 4 (Ink 4 and Ink-4) were used as black inks. 9), a test pattern was printed using special paper (coated paper) of Color Bubble Jet Cobia 1 as a recording material, and evaluation was performed in the same manner as in Use Example 1.

Usage Example 5 The black ink print cartridge of an inkjet printer Paintjet (trade name) manufactured by Hewlett-Buckard Company in the United States was partially modified, and the inks shown in Example 5 and Comparative Example 5 (Ink 5 and Ink 10) were used. A test pattern was printed using paper (coated paper) included with the paint jet as a recording material, and evaluation was performed in the same manner as in Use Example 1.

Evaluation method and evaluation criteria T1: Water resistance of printed matter A test bead with solid printing of about 10 mm x 30 + am was left indoors for about 12 hours, and the optical density (O
D+) is measured. The test beads were immersed in still water (ion-exchanged water) for 5 minutes, then air-dried, and the optical density (002) of the test beads after immersion was measured, and the OD residual rate (=(
002/OJ) x 100 ('k)) was calculated and evaluated.

a: OD residual rate≧90 (t) b=70≦OD residual rate<90 (96) c: 50≦
OD residual rate < 70 (%i) d: OD residual rate < 5
0 (*) T2: Light resistance of printed matter to direct light A test bead with solid printing of about 10 mm x 30 mm was left indoors for about 12 hours, and the optical density (OD
+). The test bead is irradiated with xenon light for 50±3 hours using an Atlas xenon fade tester (Ci35: trade name), and the optical density (002) of the test bead after irradiation with the xenon light is measured. OD residual rate (
= COD2/001) x 100 (*)) was determined and evaluated according to the following criteria.

a: OD residual rate≧90 (t) b=70≦OD residual rate<90 C%) c: 50≦o
D residual rate < 7 0 (96>d: OD residual rate < 5
0 ('l,)T3: Discoloration due to printing left indoors (
As a method of accelerating brown discoloration, a test bead similar to T, T, was placed in a light-shielded tank where the ozone concentration was always maintained within the range of 0.1 ± 0.05%. Color difference ΔEc+i (L'a"b") of printed matter before and after test after being left for 30 minutes
was measured.

a: ΔEc+*(L"a'b') < 5b: 5≦ΔE
c,,(L”a”b”)≦10C:ΔEc,!(L”a
'b') > 1 0T4: Discoloration (green discoloration) of printed matter due to being left outside T,, A test bead similar to T2 was left outside facing a busy road out of direct sunlight and rain for 90 days. , color difference ΔE cIe of printed matter before and after test
(L"a'b') was measured.

a: ΔEc+++(L'a'b') < 5b=5≦Δ
Ec+c(L″asb*)≦10C:ΔEC1,(L″
a"b') > 1 0 (margins below) γ) 1 Co-LenT,: Water resistance of printed matter T2 = Light resistance of printed matter T3: Discoloration due to being left indoors T4: Discoloration due to being left outdoors 1 X Ink T , :Water resistance of printed material T2: Light resistance of printed material T3: Discoloration due to being left indoors T4: Discoloration due to being left outdoors - Actual 151 劃 11 RU Aadaa acaca caaac caaac (Effect) The above is clear. As described above, by using the ink and recording method of the present invention, it has become possible to obtain images with improved water resistance, light resistance, indoor discoloration properties, and outdoor discoloration properties.

Claims (4)

[Claims] (1) In the ink containing a water-soluble dye, a water-soluble organic solvent, and water, the dye contains at least a dye represented by the following general formula (A) and a dye represented by the following general formula (B). An ink featuring ▲There are mathematical formulas, chemical formulas, tables, etc.▼(A) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(B) (In the above general formulas A and B, X_1 to X_6 are lithium, sodium, potassium, and quaternary ammonium compounds. One type or a mixture is shown, and Q_1 or Q_2 represents a phenyl ring or a naphthalene ring that may have a substituent.) (2) In a recording method performed by applying ink to a recording material, the ink contains a water-soluble dye, a water-soluble organic solvent, and water, and the dye is at least a dye represented by the following general formula (A). A recording method characterized by using an ink containing a dye represented by the following general formula (B). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(A) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(B) (In the above general formulas A and B, X_1 to X_6 are lithium, sodium, potassium, and quaternary ammonium compounds. One type or a mixture is shown, and Q_1 or Q_2 represents a phenyl ring or a naphthalene ring that may have a substituent.) (3) The recording method according to claim 2, wherein recording is performed using an inkjet method. (4) The recording method according to claim 2, wherein the recording material has an ink-receiving layer made of a pigment and a binder on its surface.