JPH042113B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Industrial Application Field The present invention relates to a recording medium recorded using ink, and in particular, a recording medium that has high density of images and characters recorded on the medium, and has excellent absorbency and storage stability of recorded images. This invention relates to an inkjet recording medium. (B) Prior art and its problems The inkjet recording method uses various operating principles to fly minute droplets of ink and make them adhere to a recording medium such as paper, thereby recording images, characters, etc. , high speed, low noise, easy multi-color printing, and great flexibility in recording patterns. Furthermore, it has features such as not requiring development or fixing, and is rapidly becoming popular for various uses as a recording device for various figures including Chinese characters, color images, etc. Furthermore, images formed using the multicolor inkjet method can produce records that are comparable to multicolor printing using the plate making method or printing using the color photographic method, making it ideal for applications that require fewer copies to be produced. Since it is cheaper than photographic technology, it is being widely applied to the field of full-color image recording. Efforts have been made in terms of equipment and ink composition to use high-quality paper or coated paper used for ordinary printing and writing as the recording medium used in this inkjet recording method. However, as the performance of inkjet recording devices has improved and their applications have expanded, such as higher speeds, higher definitions, and full-color inkjet recording devices, more sophisticated characteristics have come to be required of recording media. That is, the recording medium should have a high density of ink dots and a bright and colorful color tone, and the ink should be absorbed quickly so that the ink will not run out or smudge even when the ink dots overlap. The horizontal diffusion of ink dots should not be larger than necessary, and the periphery should be smooth and not blurred. Furthermore, it is required that the resistance of the dye when the recorded image is exposed to ultraviolet rays, oxygen in the air, or water be not reduced, but preferably increased. Several proposals have been made to solve these problems. For example, JP-A-52-
No. 53012 describes inkjet recording paper, which is made by moistening a low-size base paper with a coating for surface treatment.
Further, JP-A-53-49113 discloses an inkjet recording paper in which a sheet containing urea-formalin resin powder is impregnated with a water-soluble polymer. Although these general paper type inkjet recording papers absorb ink quickly, they have the disadvantage that the periphery of dots tends to become blurred and the dot density is low. Further, JP-A No. 55-5830 discloses an inkjet recording paper having an ink-absorbing coating layer on the surface of the support, and JP-A No. 55-51583 discloses a non-colloidal pigment as a pigment in the coating layer. An example using silica powder is disclosed in JP-A-55-1829, and an example of smear paper using a two-layer structure with different ink absorption speeds is disclosed. These coated paper-type inkjet recording papers are improved over general paper-type inkjet recording papers in terms of dot diameter, dot shape, dot density, and color tone reproducibility.
Most of the inks used for these recording media are water-based inks that use water-soluble dyes, and if the image formed on the recording medium is exposed to water, the dye may dissolve again and ooze out, causing the recording to fail. There are problems that significantly reduce the value of things. Therefore, in order to improve this drawback, for example, JP-A-55-53591 discloses an example in which a water-soluble metal salt is applied to the recording surface, and JP-A-56-84992 discloses a method in which a polycationic polymer electrolyte is applied. An example of a recording medium containing on the surface is disclosed in JP-A-55-150396, and a method of applying a water-resistant agent that forms a lake with the dye in the ink after inkjet recording, and JP-A-55-150396 describes No. 56-58869 discloses a method for making a recording sheet coated with a water-soluble polymer waterproof by insolubilizing the water-soluble polymer after inkjet recording. However, with these methods, the effect of water resistance may be weak, or the water resistance agent may cause some kind of reaction with the dye, reducing the shelf life of the dye, making it difficult to achieve both sufficient water resistance and light resistance. It was quite difficult. Therefore, in order to improve the light resistance, for example, JP-A-54-68303, JP-A-54-85804 and JP-A-56-
No. 18151 discloses an example in which an ultraviolet absorber is added to an ink liquid. However, these ultraviolet absorbers have problems in that they reduce the jetting stability of the ink and have low solubility, so they cannot be added in large amounts and are less effective when added in small amounts. Another solution is to incorporate ultraviolet absorbers such as benzophenone and benzotriazole into the inkjet recording sheet according to JP-A-57-74192.
No. 57-74193 and No. 57-87988, but these have poor solubility in water and are difficult to use in large amounts, are ineffective in small amounts, and are difficult to emulsify. When used as an emulsifier, there are problems such as the influence of emulsifiers. (C) Object of the Invention The present invention improves the inkjet suitability as described above, and also provides excellent water resistance and light resistance of water-based ink images, particularly the light resistance of water-soluble black dyes and/or water-soluble magenta dyes. The purpose of the present invention is to provide a recording medium with improved resistance to change and fading. (D) Structure and operation of the invention That is, the present invention provides an inkjet recording medium that forms a recorded image using a water-based ink containing a water-soluble dye, and the recording medium has the following general formula ().
This is an inkjet recording medium containing a heterocyclic compound having the structure shown below. In the formula, X basically represents C, N, O, or S. More specifically, in the formula, X is

【formula】

[Formula]=N-,

[Formula] -O- or -S- (where R ₁ , R ₂ , R ₃ , R ₄ are H or -
substituents such as OH, -CH3 _, etc.). Also, C in the formula
The double bond represented by =N- may be conjugated with other constituents of the compound. Also, the heterocycle is -X
It is a 5-membered ring or a 6-membered ring containing -C=N-, and may further form a polycyclic ring with other constituent elements. In the present invention, compounds having the structure of general formula () include:

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

Examples include [Formula]. Further, there is no problem in using these heterocyclic compounds together with hindered phenol antioxidants, benzotriazole-based or benzophenone-based ultraviolet absorbers, and the like. Furthermore, in order to apply it to a recording medium, it is also possible to use it as a metal salt, introduce a water-soluble group, or emulsify it and dissolve it in water or a suitable solvent as it is. The content of the heterocyclic compound ( ) in the recording medium is 0.2 to 100 mmol/m ² , preferably
It is 1.0-50 mmol/ ^m2 . In the present invention, the method for producing a recording medium containing the heterocyclic compound () is as follows: When valve fibers are disintegrated into a slurry and made into paper using a paper machine, the heterocyclic compound () is prepared using a size press device installed midway. A method of incorporating a dissolved or dispersed coating liquid by dipping or coating, and a method of applying a coating liquid containing a heterocyclic compound () to a support using a normal coating device to coat the heterocyclic compound (). There are a method of providing an ink-receiving layer containing the ink-absorbing pigment, a method of applying a dissolved or dispersed heterocyclic compound () on the ink-receiving layer made of an ink-absorbing pigment, an adhesive, and the like. In this case, it is also possible to use commonly used fillers, pigments, adhesives and other additives. In addition, if it is necessary to impart water resistance to the image, it is possible to use a cationic resin in combination, and in the present invention, it is rather actively used in order to simultaneously improve water resistance and light resistance. It is desirable to do so. Examples of fillers or pigments that can be used in the present invention include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, and diatom. White pigments such as earth, calcium silicate, magnesium silicate, synthetic amorphous silica, aluminum hydroxide, alumina, lithobon, etc. and organic pigments include styrene plastic pigments, acrylic plastic pigments, microcapsules, urea resin pigments, etc. be. Among these, synthetic amorphous silica and aluminum hydroxide are preferably used in the present invention. The cationic resin referred to in the present invention refers to a monomer, oligomer, or polymer that dissociates and exhibits cationic properties when dissolved in water, preferably having a quaternary ammonium group, and particularly preferably the following () to () Refers to a compound having a structure represented by the general formula. In the formula, R ₁ , R ₂ , R ₃ are alkyl groups, m is 1 to 7,
n represents 2 to 20, and Y represents an acid group. In the formulas () to (), R ₁ and R ₂ are −CH ₃ and −CH _2
-CH3 , _-CH2 - _CH2 -OH and Y represent acid groups. () Polyalkylene polyamine dicyandiamide ammonium salt condensate Examples of the compound represented by the general formula () include Nalpoly 607 (manufactured by Nalco Chemical Co., Ltd.) and Polyfix 601 (manufactured by Showa Kobunshi Co., Ltd.). The compounds represented by general formulas () to () are polydiallylamine derivatives, obtained by cyclopolymerization of diallylamine compounds, and Percoll 1697
(Allied Colloids), Cat Floe (Calgon)
Corp), PAS (Nitto Boseki Co., Ltd.), Neo Fixtures
Examples include RPD (manufactured by NICCA Chemical Co., Ltd.). Furthermore, examples of the compound represented by the general formula () include Neofix RP-70 (manufactured by NICCA Chemical Co., Ltd.). The content of the cationic resin represented by these general formulas () to () is usually 0.1 to 4 g/m ² , preferably 0.2 to 2 g/m ² . Examples of adhesives that can be used in the present invention include:
Acid starch, etherified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, casein, gelatin, soy protein,
Polyvinyl alcohol and its derivatives, maleic anhydride resins, conjugated diene polymer latexes such as ordinary styrene-butadiene copolymers, methyl methacrylate-butadiene copolymers, and polymers or copolymers of acrylic esters and methacrylic esters. Acrylic polymer latex such as ethylene vinyl acetate copolymer, vinyl polymer latex such as ethylene-vinyl acetate copolymer, functional group-modified polymer latex with monomers containing functional groups such as carboxyl groups of these various polymers, melamine resin. , urea resin, etc., and synthetic resin adhesives such as polymethyl methacrylate, polyurethane resin, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, and alkyd resin. , used alone or in combination. These adhesives contain 2 parts per 100 parts of pigment.
Parts to 120 parts, preferably 5 parts to 70 parts, are used, but the ratio is not particularly limited as long as it is sufficient to bind the pigment. However, if 120 parts or more of adhesive is used, the adhesive film formation reduces the void structure or makes the voids extremely small, which is not preferable. Other additives include pigment dispersants, thickeners,
Fluidity modifier, antifoaming agent, foam suppressor, mold release agent, foaming agent, penetrating agent, colored dye, colored pigment, fluorescent whitening agent,
UV absorbers, antioxidants, preservatives, anti-bacterial agents,
A waterproofing agent and the like may also be added as appropriate. As the support, a sheet material such as paper or thermoplastic resin film is used. In the case of paper, it is paper with no sizing agent added or with appropriate sizing, and may or may not contain filler. In the case of thermoplastic films, transparent films such as polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate, cellulose acetate, polyethylene, polycarbonate, etc., and white opaque films filled with white pigment or formed by fine foaming are used. As the white pigment to be filled, many pigments are used, such as titanium oxide, calcium sulfate, calcium carbonate, silica, clay, talc, and zinc oxide. It is also possible to use so-called laminated paper, which is obtained by pasting these resin films on the surface of paper or by processing it with molten resin. A subbing layer or corona discharge processing may be applied to improve the adhesion between the resin surface and the ink receiving layer. A sheet simply coated on a support can be used as it is as a recording sheet according to the present invention, but it may also be heated and/or passed between roll nips under pressure using a super calender, gloss calender, etc. to impart surface smoothness. It is possible.
In this case, the degree of processing may be limited because excessive processing by supercalendering will reduce the ink absorbency due to the carefully formed voids between particles. The aqueous ink referred to in the present invention is a recording liquid comprising the following colorant, liquid medium, and other additives. As the coloring agent, water-soluble dyes such as direct dyes, acid dyes, basic dyes, reactive dyes, and food colorings are preferably used. For example, as a direct dye,

【table】

【table】

[Table] etc. In addition, water-based ink liquid media include water and various water-soluble organic solvents, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol,
Alkyl alcohols having 1 to 4 carbon atoms such as sec-butyl alcohol, tert-butyl alcohol and isobutyl alcohol; Amides such as dimethylformamide and dimethylacetamide; Ketones or ketone alcohols such as acetone and diacetone alcohol; tetrahydrofuran and dioxane Ethers such as polyethylene glycol, polypropylene glycol, etc.; polyalkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. Alkylene glycols having 2 to 6 alkylene groups; examples include lower alkyl ethers of polyhydric alcohols such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl ether. Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferred. Other additives include, for example, PH regulators, metal sequestrants, antifungal agents, viscosity regulators, surface tension regulators, wetting agents, surfactants, and rust preventives. According to the present invention, when recording is performed using an aqueous ink containing an aqueous dye on a recording medium containing a heterocyclic compound having the structure of general formula (2), the light fastness of an image is improved. The reason for this is not clear, but it is thought that the fading or discoloration of dyes is due to photooxidation caused by ultraviolet rays, etc., and that the heterocyclic compound having the structure of general formula () suppresses this photooxidation reaction. Conceivable. Ink jet suitability was measured by the following method. Light resistance was measured using a xenon fade meter (Suga Test Instruments Co., Ltd.) for the image area obtained by solid printing with C, M, Y, and Bk inks using a Canon inkjet printer (A-1210). Manufactured by FAL-
25X-HCL type) at 40℃, 60%, illuminance 41w/ ^m2 16
The color density before and after irradiation was measured using a Macbeth densitometer RD514, and the percentage of the color density after irradiation divided by the color density before irradiation was expressed as light resistance (residual rate). In addition, after measuring the reflectance before and after irradiation every 10 nm using a spectral reflection densitometer (Hitachi Color Analyzer Model 607), X, Y, and Z were measured using the C light source system described in JIS-Z-8722. After calculation JIS-Z-8730
Accordingly, calculate L, a, b and find the chromaticity difference △E before and after irradiation.
I got it. This value was shown as the amount of discoloration. Water resistance was determined by using the same Canon inkjet printer to print solid images using C, M, Y, and Bk inks, immersing them in running water at 30°C for 3 minutes, and measuring the density before and after immersion using Macbeth density. The water resistance value was determined by dividing the concentration after immersion by the concentration before immersion. The higher the value, the better the water resistance. The ink absorption speed is measured immediately after solid red printing (magenta + yellow) (about 1 second) using a Sharp or Canon inkjet printer.
The paper was fed to the paper, and the paper was brought into contact with a paper presser roll or a finger, and judgment was made based on whether dirt appeared. (E) Examples The present invention will be described below with reference to examples, but the invention is not limited to these examples. In addition, parts and percentages shown in the examples mean parts by weight and percentages by weight. Examples 1 to 3 80 parts of LBKP in 370 ml CSF, 400 ml water
20 parts of NBKP of CSF, 13 parts of ground calcium carbonate,
1 part cationic starch, alkyl ketene dimer sizing agent (Harcon W, manufactured by Deitsku Hercules)
From a slurry consisting of 0.08 parts of polyalkylene polyamine epichlorohydrin resin and 0.4 parts of polyalkylene polyamine epichlorohydrin resin, base paper with a basis weight of 68 g/m ² is made using a Fourdrinier paper machine, and during paper making, 2 g/m2 of oxidized starch is added in solids using a size press machine.
^m2 was deposited to produce coated base paper. The Steckigt size degree of this base paper was 21 seconds. As a coating liquid, 100 parts of synthetic silica (Thyroid 74, manufactured by Fuji Davison Co., Ltd.), 65 parts of polyvinyl alcohol (PVA110, manufactured by Kuraray Co., Ltd.), 5 parts of a cationic resin (Polyfix 601, manufactured by Showa Kobunshi Co., Ltd.), and an antifoaming agent. A small amount of liquid with a solid content of 18% was prepared, coated to a solid content of 10 g/m ² and dried to produce a base paper with an ink-receiving layer. Separately, as a coating liquid, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 2-
Example 1 A solution prepared by dissolving 1 part each of mercaptobenzoxazole in 99 parts of ethanol was applied onto the surface of the base paper to a solid content of 0.5 g/m ² , dried, and then lightly supercalendered to finish. -3 recording paper. Table 1 shows the results of measuring the inkjet suitability of this recording paper. Comparative Example 1 A recording paper of Comparative Example 1 was prepared in exactly the same manner as in Example 1, except that 2-mercaptobenzothiazole was removed from the coating solution used in Example 1. Table 1 shows the results of measuring the inkjet suitability of this recording paper. Examples 4 to 6 80 parts of LBKP in 370ml CSF, 400ml water level
20 parts of talc and 0.5 parts of cationic starch (Cato F, manufactured by Oji National Co., Ltd.) were added to a pulp slurry consisting of 20 parts of NBKP of CSF, and paper was made using a Fourdrinier paper machine with a basis weight of 65 g/ ^m2 , and a size press was used during paper making. Polyvinyl alcohol (PVA117, manufactured by Kuraray) 2
%, white carbon (Nipsil LP, Nippon Silica Co., Ltd.) 6%, 5-mercapto-1-methyltetrazole-sodium salt 0.2, 2.0, 4.0%, respectively.
Apply Pires liquid 60g/ ^m2 and finish after drying through a machine calender Examples 4 to 6
It was used as a recording paper. Table 1 shows the results of measuring the inkjet suitability of this recording paper. Comparative Example 2 5-mercapto- with the size press liquid of Example 4
2.0% 1-methyltetrazole-sodium salt
A recording paper of Comparative Example 2 was prepared in exactly the same manner as in Example 4 except that methylisothiourea sulfate was used.
Table 1 shows the results of measuring the inkjet suitability of this recording paper.

【table】

[Table] (F) Effect of the invention As is clear from Table 1, in Examples 1 to 6 containing the heterocyclic compound according to the present invention in the recording medium, black ink images and magenta ink were The light fastness and photofading of images are significantly improved.

Claims (1)

[Scope of Claims] 1. An inkjet recording medium in which a recorded image is formed using an aqueous ink containing a water-soluble dye, wherein the recording medium contains a heterocyclic compound having a structure represented by the following general formula (). An inkjet recording medium characterized by: () (In the formula, X basically represents C, N, O, or S. Also, the double bond represented by C=N- in the formula may be conjugated with other constituent elements of the compound.)