JPH0770498A - Printing ink - Google Patents

Abstract

PURPOSE:To provide a printing ink enabling full-color printed materials of both high denseness and resolution with excellent gradation expression to be obtained even in the case of shallow intaglios by specifying both the colorant content and viscosity of a printing ink comprising a colorant, binder and aqueous medium. CONSTITUTION:The printing ink 10-1000 (pref. 15-500)CPS in viscosity comprising (A) 8-30wt.% of a colorant, (B) a binder (e.g an aqueous solution-type resin) and (C) an aqueous medium (e.g. water or its mixture with, e.g. methanol).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing ink suitable for intaglio printing. More specifically, the present invention relates to a printing ink suitable for printing using an intaglio plate having a relatively shallow plate depth such as an intaglio plate produced by a laser plate making method.

[0002]

2. Description of the Related Art In recent years, various high-speed, high-resolution printing methods have been proposed with the spread of desktop publishing for word processors, personal computers, etc. However, these are not suitable for printing a large number of copies, and a full-color image is not printed. However, there is a problem in that it cannot be printed with excellent gradation expression.

On the other hand, as a printing method suitable for printing a large amount of full-color images excellent in gradation expression, for example, there is a gravure printing method. The intaglio used in this gravure printing is generally a metal intaglio prepared by a plate making method such as a conventional gravure method, a halftone dot gravure method, or a mechanical engraving method. However, the manufacturing process of this intaglio is complicated, and the manufacturing equipment becomes large.
Therefore, the gravure printing method has a problem that a printing plate cannot be easily produced in a short time, and also has a problem of high cost when printing a small amount.

In order to solve such problems, it is possible to easily prepare a printing plate capable of printing an image excellent in full-color gradation expression, and a printing method suitable for printing a small amount or a large amount. As a method, a method has been proposed in which a thermoplastic resin intaglio plate is produced by a laser plate making method and gravure printing is performed using the intaglio plate (Japanese Patent Laid-Open No. 2-1.
39238, etc.). This laser plate making method is a method of irradiating a plate sheet made of a thermoplastic resin with a laser beam to melt, scatter or sublime the surface of the plate sheet to form recesses, and the pulse width is modulated when the laser beam is irradiated. Or by modulating the intensity, the plate depth of the recesses (100 to 2032 line / inch) formed in the plate sheet is reduced to 0.
The intaglio plate capable of gradation printing is produced by changing the depression amount and size of the concave portion in the range of about 1 to 20 μm according to the gradation of the image. According to this laser plate making method, an intaglio plate can be produced at a low cost in a short time with a simple process as compared with general conventional gravure plate making methods such as a conventional gravure method, a halftone dot gravure method, and a mechanical engraving method. Therefore, it becomes possible to print an image excellent in full-color gradation expression both at an individual and in the office.

[0005]

However, the plate depth of the intaglio plate made of thermoplastic resin by the laser plate making method is 20 μm.
Since the depth of a metal intaglio plate by a general plate making method such as a conventional gravure method is about 50 μm, it is shallow, so that it is sufficient to use a conventional printing ink for a metal intaglio plate. There is a problem that the print density cannot be obtained, and the resolution and gradation are lowered.

The present invention is intended to solve such a problem of the prior art. Even when it is used for an intaglio having a shallow plate depth, full-color printing with high density and high resolution and excellent gradation expression is achieved. The purpose is to provide a printing ink that enables the printing.

[0007]

The present inventor has found that the above object can be achieved by adjusting the colorant to a higher concentration than a conventional printing ink and adjusting the viscosity to a predetermined range, and completed the present invention. Came to let.

That is, the present invention is characterized in that it comprises a colorant, a binder and an aqueous medium, the content of the colorant is 8 to 30% by weight, and the viscosity during printing is 10 to 1000 cps. Providing printing ink.

The present invention will be described in detail below.

The printing ink of the present invention is a water-based ink composition containing a colorant, a binder and an aqueous medium, and the content of the colorant is 8 to 30% by weight which is relatively high as compared with conventional printing inks. %, And more preferably 8 to 25% by weight. If the content of the colorant is less than this range, the desired print density cannot be obtained. As the type of colorant used in the printing ink of the present invention, various known inorganic or organic pigments can be used.

As the binder used in the printing ink of the present invention, an aqueous solution type resin, a polymer emulsion, a hydrosol type resin or the like can be used. Among them, the aqueous resin is soluble in water or alkali such as cellulose derivative, shellac, modified shellac, casein, gelatin, modified protein, rosin, modified rosin, gum arabic, starch, starch derivative, dextrin, tragacanth gum, alginic acid. Natural resins and their derivatives can be used. In addition, vinyl monomer copolymers to which anionic, cationic or nonionic hydrophilic functional groups have been added to make the resin water-soluble, polyester resins, polyamide resins, polyurethane resins, petroleum resins, alkyd resins, melamine resins, phenol-formaldehyde. Resins and the like can be used, and resins such as polyethylene oxide, sodium polyacrylate, polyvinylpyrrolidone, and polyvinyl alcohol can also be used.

Further, as the polymer emulsion, acrylic type, styrene-acrylic type, shellac-vinyl type,
Resins of ethylene / vinyl acetate type, ethylene / vinyl acetate-vinyl type, petroleum resin type, polyamide-vinyl graft polymer type, urethane type, urethane-vinyl type, polyester type and the like can be used.

As the hydrosol type resin, those obtained by partially neutralizing the carboxylic acid of the aqueous solution polymerized resin, redispersed emulsion polymerized resin emulsion particles, and those polymerized in the presence of the aqueous solution type resin are used. You can
More specifically, acrylic hydrosol, urethane hydrosol, polyester hydrosol, petroleum resin hydrosol and the like can be used.

In the printing ink of the present invention, an alkaline additive can be used, if necessary, in order to dissolve the resin of the binder component as described above. Examples of such additives include sodium hydroxide, sodium carbonate, ammonium carbonate, sodium acetate, ammonium acetate, urea, thiourea, sodium silicate, disodium phosphate, trisodium phosphate, organic amines, ammonia and the like. I can give you. Among them, organic amines and ammonia are preferably used, and specific examples of the organic amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, isopropylamine, diisopropylamine,
n-butylamine, n-dibutylamine, n-tributylamine, isobutylamine, diisobutylamine, s
ec-butylamine, n-amylamine, diamylamine, triamylamine, sec-amylamine, sec
Alkylamines such as hexylamine, 2-ethylbutylamine, n-heptylamine, 2-ethylhexylamine, dioctylamine, ethylenediamine, propyleneamine, diethylenetriamine, monoethanolamine, diethanolamine, triethanolamine, ethylmonoethanolamine, n -Butylmonoethanolamine, ethylmonoethanolamine, n-butylmonoethanolamine, dimethylethanolamine, diethylethanolamine, ethyldiethanolamine, n-
Butyldiethanolamine, di-n-butyldiethanolamine, triisopropanolamine, isopropanolamine, 2-amino-2-methylpropanol, 2
Examples thereof include alkanolamines such as dimethylamino-2-methyl-1-propanol, amino alcohols, and nitrogen-containing heterocyclic compounds such as morpholine.

These organic amines and ammonia can be used alone or in combination of two or more kinds. However, the stability of the ink with time, the fluidity and the drying property are improved, and the reconstitution of the ink once solidified. From the viewpoint of ensuring solubility, it is preferable to combine them appropriately. The addition amount of the organic amines or ammonia is preferably determined appropriately according to the type and the acid value of the resin as the binder component, and is usually 10 to 40 with respect to 100 parts by weight of the resin.
It is preferable to use parts by weight.

The aqueous medium used in the printing ink of the present invention contains water as a main component and, if necessary, contains alcohols such as methanol, ethanol, n-propyl alcohol and isopropyl alcohol which are easily miscible with water. be able to. In addition, alcohols such as n-butanol, isobutanol, sec-butanol, and tert-butanol that are not easily miscible with water can be contained as long as the amount that dissolves in water is used.

When alcohols are contained in the aqueous medium, the content thereof in the printing ink is 40 with respect to the whole printing ink from the viewpoint of improving the stability of the printing ink.
It is preferable to set the content to be not more than weight%. It should be noted that it is preferable to suppress the amount of alcohols used from the viewpoint of work safety when manufacturing the printing ink.

The printing ink of the present invention comprises, in addition to the above-mentioned coloring agent, binder and aqueous medium, a wax, a slow-drying solvent, a drier, a dispersant, a wetting agent, a defoaming agent and a leveling, if necessary. Agents, thickeners, stabilizers, preservatives,
It may contain a plasticizer, a surface tension adjusting agent, oils, an extender pigment and the like. Particularly, in the printing ink of the present invention, since the content of the colorant is large, the colorant may be clogged between the doctor blade and the plate sheet during printing, which may cause fogging in the printed image. To prevent fogging, it is preferable to use wax.

Examples of such waxes include paraffin wax, carnauba wax, montan wax, candelilla wax, sazol wax, polyethylene wax, polyethylene oxide wax, polyethylene and tetrafluoroethylene resin mixture, polyethylene oxide and tetrafluoride. A finely-divided ethylene resin mixture, tetrafluoroethylene, sorbitan fatty acid ester, polyamide wax, or the like can be used.

The amount of wax to be added depends on the type of wax to be added, etc., but in general, the binder resin 10 is used.
0.1 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 0 parts by weight.

The slow-drying solvent is ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, propylene glycol methyl. Ether acetate, polyethylene glycol, polypropylene glycol, triethylene glycol, diethylene glycol ethyl ether, diethylene glycol, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether and the like can be used.

The printing ink of the present invention can be produced by blending the above-mentioned components according to a conventional method, and the viscosity at the time of printing can be 10 to 10 by appropriately adjusting the blending ratio of each component. Make it 1000 cps. That is, the appropriate printing speed during printing is generally 20 to 2
Although it is set to 00 m / min, at such an appropriate printing speed, the viscosity is set to 1000 cps or less when the printing speed is set to 20 m / min or more, and the printing speed is set to 2
The viscosity is set to be 10 cps or more when it is set to 00 m / min or less. When printing at an appropriate printing speed, if the viscosity of the printing ink is less than 10 cps, the edge cut of the doctor on the plate sheet is inferior, and the ink swimming of the printed matter becomes severe. Therefore, the dot reproducibility of the image is deteriorated, the gradation reproducibility is also inferior, and it becomes difficult to obtain a high-quality printed image. On the other hand, when printing is performed at an appropriate printing speed, even when the viscosity of the printing ink exceeds 1000 cps, the edge cut of the doctor is inferior and ink swimming occurs, which causes a problem such as fog in the printed image.

The viscosity of the particularly preferable printing ink varies depending on the printing conditions applied to the printing ink, but for example, an intaglio plate (100 to 2032 line / inch) made of a thermoplastic resin is used, and the printing speed is 20 to 200 m / If min
The viscosity of the printing ink is preferably 15 to 500 cps.

There is no particular limitation on the printing method in which the printing ink of the present invention can be used, but it is like an intaglio plate made of a thermoplastic resin prepared by a laser plate making method, or an intaglio plate prepared by using an electron beam or the like instead of a laser. In addition, it can be suitably used for gravure printing using an intaglio plate having a relatively shallow plate depth (for example, an intaglio plate having a plate depth of about 20 μm or less).

When the printing ink of the present invention is used for a thermoplastic resin intaglio plate prepared by a laser plate making method, the plate sheet constituting the intaglio plate may be polyethylene, polypropylene, polyester, polyacrylic ester, polystyrene. , Polyvinylidene chloride, polycarbonate, ethylene / vinyl acetate copolymer, ethylene /
Acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl acetate, urethane, polyacrylonitrile, polybutene, polyacetal, polyamide, polyimide, aramid, ionomer, nitrified cotton, polyethylene naphthalate, methyl terpene copolymer, polyfluorine Resin sheet made of a resin containing one or more of vinyl chloride, fluorine resin, ethylene monoxide trifluoride ethylene, tetrafluoride ethylene, carboxylated olefin, etc., or a resin sheet made of a laminate of these resins, or A resin sheet coated with a coating agent composed of one or a plurality of thermoplastic resins, thermosetting resins, isocyanate-curing resins, acid-curing resins, UV-curing resins, EB-curing resins, etc. Such a resin sheet, iron, aluminum, stainless steel, It may be used lead, nickel, etc. formed by bonding on a metal plate such as copper. Such a plate sheet is usually used by winding it around a metal cylinder or a cylinder laminated with rubber at the time of printing, but even if the plate sheet is formed into a tubular shape instead of a sheet shape and is attached to the cylinder and used. Good.

[0026]

According to the present invention, the content of the colorant in the printing ink containing the colorant, the binder and the aqueous medium is 8 to 30% by weight, which is higher than that of the conventional intaglio printing ink. It is possible to perform high-density printing even when using an intaglio plate having a shallow printing depth. further,
Since the viscosity of the printing ink during printing is adjusted to 10 to 1000 cps, it is possible to obtain a full-color printed image with high resolution and excellent gradation expression at an appropriate printing speed.

[0027]

EXAMPLES The present invention will be described in detail below based on examples.

Examples 1 to 8 Yellow pigments, magenta pigments, cyan pigments, black pigments and other ink components were mixed in the proportions shown in Tables 1 and 2, and the components were dispersed by a ball mill to prepare printing inks.

The viscosity of the obtained ink was measured with a BL adapter at 60 rpm and 20 ° C. using a B type rotational viscometer. The results are shown in Tables 1 and 2.

[0030]

[Table 1]

[0031]

[Table 2] Comparative Examples 1 to 8 Yellow pigments, magenta pigments, cyan pigments, black pigments and other ink components were mixed in the proportions shown in Tables 3 and 4, and each component was dispersed by a ball mill in the same manner as in Examples 1 to 8 to produce a printing ink. Was prepared. Moreover, the viscosity of the obtained ink was measured in the same manner as in Examples 1 to 8. The results are shown in Tables 3 and 4.

[0032]

[Table 3]

[0033]

[Table 4] Comparative Examples 9 to 16 Yellow pigments, magenta pigments, cyan pigments, black pigments,
Other ink components were mixed in the ratios shown in Tables 5 and 6 to prepare printing inks. Moreover, the viscosity of the obtained ink was measured in the same manner as in Examples 1 to 8. The results are shown in Tables 5 and 6.

[0034]

[Table 5]

[0035]

[Table 6] Evaluation Using the inks obtained in Examples and Comparative Examples, intaglio printing was performed under the following conditions. And Examples 1-8,
The printed matter of Comparative Examples 1 to 8 was evaluated for edge breakage, ink swimming, plate fog, dot reproducibility, and printability as follows. The results are shown in Table 8.

The marks of Examples 1 to 8 and Comparative Examples 9 to 16 were also used.
The reflection density and brightness of the printed matter were measured as follows. these
The results are shown in Table 9.Printing conditions  (1) Plate type of plate sheet: thermoplastic resin sheet Plate manufacturing method: laser plate making method Pitch: 400 line / inch Recessed shape: 12 grades as shown in Table 7
Hole shape

[0037]

[Table 7] (2) Printed material Cast coated paper (3) Printing speed 50 m / min (4) Printing temperature 20 ° C Evaluation method (1) Edge breakage: Very good ◎, good ○, slightly bad △, bad × by visual observation It was evaluated in four levels. (2) Ink swimming: By visual observation, it was evaluated in four grades of very good ◎, good ○, slightly bad Δ, and bad ×. (3) Plate Fogging: Visually observed, and evaluated in four grades of very good ⊚, good ∘, slightly bad Δ, and bad ×. (4) Dot reproducibility: By visual observation, evaluation was made in four grades of very good ⊚, good ∘, slightly bad Δ, and bad ×. (5) Printability: From a comprehensive viewpoint including print conditions and print finish, printability was evaluated in four grades of very good ◎, good ○, slightly bad Δ, and bad ×. (6) Reflection Density: A Macbeth reflection densitometer was used to measure the reflection density (OD value) for each gradation. (7) Luminance: The gloss value was measured at an incident angle of 60 ° and a light receiving angle of 60 °. The brightness of the cast coated paper used as the material to be printed was 72 °.

[0038]

[Table 8]

[0039]

[Table 9] From the results of Table 8, Comparative Examples 1 to 4 having a viscosity of less than 10 cps
In Comparative Example 5 where the edge breaks, ink swimming, dot reproducibility and printability are poor, and the viscosity exceeds 1000 cps
It can be seen that from No. 8 to 8 the plate fog and printability are inferior and high quality printed matter cannot be obtained. On the other hand, in Examples 1 to 8 of the present invention, it is understood that high-quality printed matter can be obtained with good edge breakage, ink swimming, plate fog, dot reproducibility, and printability.

Further, when the reflection densities of the examples and the comparative examples are compared in Table 9, for example, the reflection densities of gradation No. 12 of the yellow pigment are 1.36 in the examples 1 and 5.
Although it is 1.38, it is 0.60 to 0.6 in Comparative Examples 9 and 13.
2, which is about twice as high as that of the comparative example,
Further, it can be seen that the gloss value of the example is about twice as high as that of the comparative example. Therefore, it can be seen that the ink of the example can form a printed image of extremely high density and high brightness as compared with the ink of the comparative example having a low pigment concentration.

[0041]

According to the printing ink of the present invention, even when it is used for an intaglio having a shallow plate depth, it is possible to perform full-color printing with high density and high resolution and excellent gradation expression.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a shape of a hole formed in a plate sheet.

[Explanation of symbols]

 1 plate sheet 2 holes

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeyoshi Hirashima 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Osamu Majima 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo No. Sony Corporation

Claims (4)

[Claims] 1. A printing ink comprising a colorant, a binder and an aqueous medium, wherein the content of the colorant is 8 to 30% by weight and the viscosity during printing is 10 to 1000 cps. 2. Further, 10 to 4 organic amines or ammonia are added to 100 parts by weight of a resin as a binder component.
The printing ink according to claim 1, which contains 0 part by weight. 3. The printing ink according to claim 1, wherein the aqueous medium contains alcohols, and the alcohols are contained in an amount of 40% by weight or less based on the whole printing ink. 4. The printing ink according to claim 1, further comprising 0.1 to 20 parts by weight of wax with respect to 100 parts by weight of a resin as a binder component.