JPH09124987A - Electrostatic gravure printing ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an electrostatic gravure printing ink which can eliminate problems associated with a reduction in depth of a plate, recycling of a solvent, removal of an ink from an intaglio printing plate, and elimination to need the use of an arom. solvent and a plurality of solvents by adding a charge- donating compd. to fine particles of a colored resin dispersed in an inorg. solvent. SOLUTION: Fine particles of a colored resin are dispersed in a nonpolar solvent, and a charge-donating compd. is added thereto to prepare a non-aq. resin dispersion type ink for electrostatic gravure printing. This ink is used in a printing device wherein a d.c. voltage can be applied between a gravure cylinder plate (3) and a counter electrode (4) or between a gravure cylinder plate (3) and an impression cylinder (6). A voltage difference is provided between the gravure cylinder plate (3) and the counter electrode (4) in an ink pan (1) containing an ink to deposit an ink onto the gravure cylinder plate (3). After the ink on the non-image area is scraped by means of a doctor blade (5), a potential difference is provided between the gravure cylinder plate (3) and the impression cylinder (6) to transfer the ink to a printing material (7).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel ink used for electrostatic gravure printing. More specifically, for electrostatic gravure printing, a colored resin fine particle in which a resin fine particle and a pigment are dispersed in a nonpolar solvent is formed, and a charge-giving compound for imparting an electric charge to the colored resin fine particle is added. The present invention relates to a non-aqueous resin dispersion type ink.

[0002]

2. Description of the Related Art In gravure printing, ink having a large fluidity is used, and the ink on the plate supplied is scraped off by a doctor blade while rotating, and the ink remaining in the cells of the concave portion of the gravure cylinder plate is printed. The image is formed by transferring it to a printing medium such as a film or a film. Gravure printing uses various aromatic solvents and other solvents singly or as a mixture in order to impart various types of resistance to the printed matter and to perform sufficient drying.
Used by dissolving various resins and dispersing pigments. Therefore, there is a problem in that the solvent evaporated by drying is harmful to the human body for hygiene and it is difficult to separate and recover (economically recover) into a single component because a mixed solvent is used.

Further, in order to obtain a printed matter having a sufficiently high density, it is necessary to increase the concentration of the pigment and the vehicle in the ink, but it is inconsistent in terms of physical properties to produce a high concentration and low viscosity. Good ink cannot be obtained. Therefore, in order to perform printing with sufficiently high density, the plate depth of the gravure plate is made deep to 40 to 50 μm. The use of such deep plates results in an increase in the amount of organic solvent exhausted during printing. The print quality of gravure printing is so important that it is said to be determined by the plate making of the plate cylinder. However, the transfer of ink to paper or plastic film is easily affected by printing pressure and ink tack. If the transfer of ink is poor, the color tone will be poor and color unevenness will occur. In particular, there is a "frost phenomenon" that occurs remarkably in highlights and halftones. The cause of this "frost frost phenomenon" is that the ink in the cells of the plate cylinder and the printing medium do not contact each other due to the surface roughness of the printing medium, Because it has stopped moving to. For this reason, the printing pressure is further increased so that the material to be printed and the ink come into contact with each other to reduce the "frost fringing phenomenon", but if too large a printing pressure is applied, the plate cylinder and the impression cylinder may be twisted. The problem was that the rubber of the impression cylinder was damaged.

[0004]

DISCLOSURE OF THE INVENTION It is an object of the present invention to make a plate shallower, to recycle solvent, to remove ink from an intaglio plate,
The present invention relates to a novel non-aqueous resin-dispersed ink having a charge for electrostatic gravure printing that solves the problems of conventional gravure printing such as elimination from aromatic solvents and elimination from multiple solvents.

[0005]

SUMMARY OF THE INVENTION The present invention provides a gravure cylinder plate, a counter electrode body adjacent to the gravure cylinder plate, which is immersed in ink, and a direct current between a gravure cylinder plate and an impression cylinder coated with a conductive rubber. In a printing device capable of applying a voltage, a voltage difference is provided between the gravure cylinder plate and a counter electrode body in an ink pan containing ink,
Ink is attached to the gravure cylinder plate, and further,
An ink used in a printing method in which after the ink in the non-image area is scraped off by a doctor blade, the ink is transferred to a printing medium by providing a potential difference between the gravure cylinder plate and the impression cylinder. Forming a colored resin fine particle in which resin fine particles and a pigment are dispersed in a non-polar solvent, and adding a charge-imparting compound for imparting an electric charge to the colored resin fine particle, a non-aqueous resin for electrostatic gravure printing. It is a dispersion type ink.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a colored resin fine particle, which is a dispersion of a pigment and a resin, has an electric charge and is dispersed in a single solvent. A low-viscosity ink system is produced at a concentration, and the charged ink is moved by forming electric lines of force in each process. Therefore, the gravure cylinder plate is made shallow, the aromatic solvent is removed, and The problem of conventional gravure printing is solved by recycling with a solvent and facilitating ink removal from the intaglio plate.

The advantages of the present invention are summarized below. The transfer of the ink causes the electrically charged ink to transfer from the ink pan to the gravure cylinder plate and from the gravure cylinder plate to the printing medium, thereby preventing color loss from highlight to halftone. The printing pressure can be reduced depending on the smoothness of the material to be printed. Therefore, the life of the impression cylinder and the gravure cylinder plate is extended. Solvent recovery can be facilitated by removing the toluene and using an aliphatic solvent as a single solvent. Since the non-aqueous resin dispersion type ink is used, the viscosity of the gravure cylinder plate can be reduced because the viscosity can be reduced at a high concentration.

The gravure cylinder plate is an intaglio plate made by a normal gravure plate making method.
(1) Conventional gravure, (2) Net gravure,
(3) It is roughly divided into sculpture gravure. The solvent used for the non-aqueous resin dispersion type ink is a highly insulating organic non-polar solvent having an electric resistivity of 10 ¹⁰ Ω · cm or more and a dielectric constant of 3 or less. Coronasha Showa 6
It belongs to an isoparaffinic solvent as described in June 15, 3) and is commercially available under trade names such as Isopar (Exxon), isododecane (British petroleum), and IP solvent (Idemitsu Petrochemical).

In the non-aqueous resin dispersion type ink, first, fine resin particles are prepared in a non-polar solvent by a synthetic method, and then colored resin particles of about 0.1 μm to 3 μm colored with a pigment are suspended, and a charge is imparted. A compound was added. "Basics and applications of electrophotographic technology" as charge-giving compounds
The following compounds as described in (Corona Publishing, June 15, 1988) can be used. Positive polarity charge imparting compound: metal salt of naphthenic acid, octylic acid, stearic acid, etc., ethylenediaminetetraacetic acid metal complex salt, etc. Negative charge imparting compound: calcium alkylbenzene sulfonate, calcium dioctyl sulfonate, sodium dioctyl sulfonate, monolauryl phosphate As the pigment used, zinc, methylene chloride copper phthalocyanine, rosin-modified maleic acid resin, lecithin, or the like, those conventionally used for gravure printing inks can be used in the present invention. For example,
Hansa Yellow, Disazo Yellow, Quinoline Yellow, Permanent Yellow, Benzidine Orange, Bengala, Fast Red, Resole Red, Permanent Red, Watchyan Red Manganese Salt, Pyrazolone Red, Lake Red C, Lake Red D, Brilliant Carmine 3B or 6B, Navy Blue Pigments such as phthalocyanine blue, victorian blue, nigrosine and carbon black can be used. Further, a processed pigment in which the pigment is dispersed in high concentration in various resins in advance can also be used.

The counter electrode body is a cylinder surface-treated by alumite processing or the like which is installed with a gap of 0.1 mm to 5 mm between the counter electrode body and the gravure cylinder plate, or
The plate-shaped aluminum electrode is electrically insulated from the printing apparatus main body so that a voltage can be applied to the gravure cylinder plate. Further, the impression cylinder is a metallic cylinder and has an electric resistance value of 10 ⁸ to 10 ¹⁰ Ω · cm and is 1 to 2
It has a structure in which a conductive rubber having a thickness of 0 mm is coated and is electrically insulated from the main body of the printing apparatus so that a voltage can be applied between the gravure cylinder plate and the gravure cylinder plate. A general disperser can be used to disperse the non-aqueous resin dispersion type ink. An attritor, a sand mill, a ball mill, a shot mill, or a bead mill can be used as the disperser generally used. The dispersion time varies depending on the disperser, but the dispersion can be performed in several hours to 24 hours.

[0011]

EXAMPLES The present invention will be described in more detail with reference to Examples.
First, the electrostatic printing method of the present invention will be described with reference to FIG. Put the non-aqueous resin dispersion type ink (2) in the ink pan (1). The gravure cylinder plate (3) having a diameter of 120 mm rotates at a peripheral speed of 50 m / min or more during printing. Adjacent to the gravure cylinder plate, the ink pan (1)
A cylindrical counter electrode body (4) having a diameter of 50 mm immersed in the gravure cylinder plate (3) rotates in the opposite direction to the gravure cylinder plate (3) at a peripheral speed of about 1.5 times. A potential difference is provided between the gravure cylinder plate and the counter electrode to electrically charge the colored resin fine particles having a charge of the non-aqueous resin type dispersion ink (2) to the gravure cylinder plate (3).
Adhere on top. A non-aqueous resin dispersion type ink having a high concentration of colored resin fine particles adhered on the gravure cylinder plate (3) is scraped off by a doctor blade (5). In the cell of the concave part of the gravure cylinder plate, the printing medium (7) passing between the gravure cylinder plate (3) and the impression cylinder (6) with a diameter of 120 mm coated with conductive rubber that rotates at the same peripheral speed. The remaining non-aqueous resin dispersion type ink is transferred by pressure and electric force. During printing, a potential difference is provided between the gravure cylinder plate (3) and the impression cylinder (6).

Further, a method for producing a non-aqueous resin dispersion of resin fine particles dispersed in a non-polar solvent used for producing a non-aqueous resin dispersion type ink will be described. In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a reflux device, IP Solvent 1620 (trade name, manufactured by Idemitsu Petrochemical) 1000 g
Is charged and saturated with nitrogen gas. After raising the internal temperature to 80 ° C., 3.0 g of benzoyl peroxide is added and uniformly dissolved. A mixed solution in which 3.0 g of benzoyl peroxide and 300 g of 2-ethylhexyl methacrylate were dissolved in advance was added dropwise for 2 hours. At the end of the dropping, 3.0 g of benzoyl peroxide is added, and the mixture is heated and aged for 2 hours, and then cooled.

A resin solution having a molecular weight of 13,000 and a solid content of 23% was obtained. (This resin solution is referred to as dispersion stabilizing resin A.) <Production Example 1 of non-aqueous resin dispersion> Dispersion stabilizing resin solution A
The dispersion stabilizing resin solution A13 was placed in the same reaction vessel in which
00 g (resin 300 g) was charged (hereinafter referred to as “charge”) and saturated with nitrogen gas, and then the temperature was raised to 80 ° C. Preliminarily benzoyl peroxide 7 g, methyl methacrylate 467
g, and 233 g of ethyl acrylate are uniformly added to the mixture (“dropping mixture”) in about 90 minutes.

Solid content of 50% by reaction, viscosity of 70 cps
To obtain a milky white non-aqueous resin dispersion. <Production Examples 2 to 7 of Non-Aqueous Resin Dispersion> In the same manner as in Production Example 1 of a non-aqueous resin dispersion, the composition and amount of the dispersion stabilizing resin, the monomer and benzoyl peroxide were changed according to the contents of Table 1. Then, non-aqueous resin dispersions 2 to 7 were obtained. In addition, as the dispersion stable resin solution B in Table 1, 12-hydroxystearic acid polyester (trade name: Solspers 2000) was used instead of the dispersion stable resin solution A to obtain non-aqueous resin dispersions 6 and 7. It is a thing.

[0015]

[Table 1]

Next, a method for producing a non-aqueous resin dispersion type ink using the non-aqueous resin dispersion obtained in the production example of the non-aqueous resin dispersion which is resin fine particles dispersed in a non-polar solvent will be described. . Parts indicate parts by weight. Example 1 (Negatively charge-adjusted non-aqueous resin dispersion type ink) The non-aqueous resin dispersion of Production Example 1 of the non-aqueous resin dispersion 50 was used.
Part, IP Solvent 1620 (trade name, manufactured by Idemitsu Petrochemical) 100 parts, Mitsubishi Carbon # 40 (Mitsubishi Chemical Corporation)
1.5 parts) was put into a vessel equipped with a stirrer, zirconia beads having a diameter of 1 mm were used as a dispersion medium, and the wetted part was circulated and dispersed in a sand mill using a ceramic-processed member for 5 hours and filtered, A colored resin fine particle dispersion liquid having colored fine particles dispersed in a nonpolar solvent having an average particle diameter of 0.1 μm was obtained.

Next, 40 parts of IP Solvent 1620 was added to 10 parts of the obtained colored resin particle dispersion, and 0.01 parts of alkylbenzene sulfonate calcium as a charge-giving compound.
Parts were added, and the mixture was mixed and stirred to obtain a non-aqueous resin dispersion type ink having a negative charge adjusted. Example 1 was performed under the following printing conditions.・ Peripheral speed of gravure cylinder plate (3): 60 mm / min ・ Peripheral speed of counter electrode (4): 100 m / min ・ Peripheral speed of impression cylinder (6): 60 m / min ・ Printing speed of printing medium (7) : 60 m / min ・ Depth of gravure cylinder plate (3): 30 μm ・ Potential difference between gravure cylinder plate (3) and counter electrode (4): 500 V However, gravure cylinder plate (3) is at ground level,
The counter electrode (4) is the negative electrode.

-Potential difference between the gravure cylinder plate (3) and the impression cylinder (6): 500 V However, the gravure cylinder plate (3) is set to the ground level,
The impression cylinder (6) is the positive electrode. Transferred onto a roll paper of NK High Coat L manufactured by Nippon Kako Kaisha Co., Ltd. at a printing speed of 60 m / min to obtain a printed matter having a sufficient film strength. A high density of 1.9 was obtained by the reflection density (Macbeth densitometer RZ-918 (manufactured by Macbeth Co.)) in the solid area density. Example 2 (Positively charge-controlled non-aqueous dispersion type ink) 50 parts of the non-aqueous resin dispersion 2 shown in Table 1 and IP solvent 1
620 (trade name, manufactured by Idemitsu Petrochemical Co., Ltd.), 100 parts of blue pigment, Lionol Blue FG7350 (manufactured by Toyo Ink Mfg. Co., Ltd.), 1.5 parts were put into a container with a stirrer, and zirconia beads of φ1 mm were used as a dispersion medium. After being circulated and dispersed for 5 hours in a sand mill using a member whose liquid contact part is ceramic-processed and filtered, a colored resin fine particle dispersion liquid having colored fine particles dispersed in a non-polar solvent having an average particle diameter of 0.2 μm is obtained. It was

Then, the obtained colored resin fine particle dispersion liquid 10 is obtained.
40 parts of IP Solvent 1620 and 0.01 part of zirconium octylate as a charge-giving compound were added to the parts, and mixed and stirred to obtain a positive charge-controlled non-aqueous resin dispersion type ink. The same apparatus as in Example 1 was used, and as the non-aqueous resin dispersion type ink (2), the above-mentioned positively charge-adjusted ink was used. Other conditions different from those of Example 1 are shown below.・ Peripheral speed of gravure cylinder plate (3): 90 mm / min ・ Peripheral speed of counter electrode (4): 150 m / min ・ Peripheral speed of impression cylinder (6): 90 m / min ・ Printing speed of printing medium (7) : 90 m / min ・ Depth of gravure cylinder plate (3): 40 μm ・ Potential difference between gravure cylinder plate (3) and counter electrode (4): 400 V However, gravure cylinder plate (3) is at ground level,
The counter electrode (4) is the positive electrode.

-Potential difference between the gravure cylinder plate (3) and the impression cylinder (6): 400 V However, the gravure cylinder plate (3) is set to the ground level,
The impression cylinder (6) serves as the negative electrode. In the same manner as in Example 1, the product was transferred onto NK high-coated paper manufactured by Nippon Kako Kaisha Co., Ltd. at a printing speed of 90 m / min while receiving a pressure of ² kg / cm ^{2 from} an impression cylinder to obtain a printed matter. The solid density of the obtained print was measured by a reflection density (Macbeth densitometer RZ-918 (manufactured by Macbeth Co.)) and was 1.8. Example 3 (Negatively charge-adjusted non-aqueous resin dispersion type ink) 50 parts of the non-aqueous resin dispersion 6 of Table 1, IP solvent 1
620 (trade name, manufactured by Idemitsu Petrochemical Co., Ltd.), 100 parts, and processed pigment, MICROLEN Magenta RT-235 (trade name, Nippon Ciba Geigy Co., Ltd.), 3.0 parts are put into a container with a stirrer, and φ1 mm zirconia beads are used as a dispersion medium. Then, the liquid contact part is circulated and dispersed for 5 hours in a sand mill using a ceramic-processed member, filtered, and then a colored resin fine particle dispersion liquid having colored fine particles dispersed in a non-polar solvent having an average particle diameter of 0.1 μm is obtained. Obtained.

Next, 40 parts of IP Solvent 1620 and 0.01 part of lecithin as a charge-imparting compound were added to 10 parts of the obtained colored resin particle dispersion, and the mixture was stirred to be a non-aqueous resin dispersion type in which the charge was adjusted to a negative value. I got ink. The same apparatus as in Example 1 was used, and as the non-aqueous resin dispersion type ink (2), the above-mentioned ink whose negative charge was adjusted was used. Other conditions different from those of Example 1 are shown below.・ Peripheral speed of gravure cylinder plate (3): 70 mm / min ・ Peripheral speed of counter electrode (4): 100 m / min ・ Peripheral speed of impression cylinder (6): 70 m / min ・ Printing speed of printing medium (7) : 70 m / min ・ Depth of gravure cylinder plate (3): 30 μm ・ Potential difference between gravure cylinder plate (3) and counter electrode (4): 500 V However, gravure cylinder plate (3) is at ground level,
The counter electrode (4) is the negative electrode.

-Potential difference between the gravure cylinder plate (3) and the impression cylinder (6): 500 V However, the gravure cylinder plate (3) is set to the ground level,
The impression cylinder (6) is the positive electrode. In the same manner as in Example 1, NK high-coated paper manufactured by Nippon Paper Industries Co., Ltd. was used, and 1.5 kg / cm by an impression cylinder
Transfer was performed at a printing speed of 70 m / min while receiving a pressure of ² to obtain a printed matter. Transferred onto a roll paper of NK High Coat L manufactured by Nippon Kako Kaisha Co., Ltd. at a printing speed of 70 m / min to obtain a printed matter having a sufficient film strength. A high density of 1.9 was obtained by the reflection density (Macbeth densitometer RZ-918 (manufactured by Macbeth Co.)) in the solid area density.

[0023]

INDUSTRIAL APPLICABILITY According to the present invention, a colored resin fine particle, which is a dispersion of a pigment and a resin, has an electric charge, and further, by using a non-aqueous resin dispersion type ink in which it is dispersed in a single solvent, Introduces an ink system with low viscosity at a concentration and moves the charged ink by forming lines of electric force in each process, thus making the gravure cylinder plate a shallow plate, escaping from an aromatic solvent, The problem of conventional gravure printing is solved by recycling with a solvent and facilitating ink removal from the intaglio plate.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram of the present invention.

[Brief description of reference numerals]

 (1) Ink pan (2) Non-aqueous resin dispersion type ink (3) Gravure cylinder plate (4) Counter electrode body (5) Doctor blade (6) Impression cylinder (7) Printed material

Claims (1)

[Claims] 1. A printing method in which a DC voltage can be applied between a gravure cylinder plate, a counter electrode body adjacent to the gravure cylinder plate, which is immersed in ink, and an impression cylinder coated with a conductive rubber, which is in pressure contact with the gravure cylinder plate. In the apparatus, a voltage difference is provided between the gravure cylinder plate and the counter electrode body in the ink pan containing the ink, the ink is attached to the gravure cylinder plate, and the ink in the non-image area is scraped off by the doctor blade. An ink used in a printing method in which an ink is transferred to a printing medium by providing a potential difference between the gravure cylinder plate and the impression cylinder,
For the electrostatic gravure printing, the ink is characterized by forming colored resin fine particles in which resin fine particles and a pigment are dispersed in a non-polar solvent, and adding a charge-imparting compound for imparting an electric charge to the colored resin fine particles. Non-aqueous resin dispersion type ink.