JPS597588B2 - Suisei Ink Insatsuhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for imparting a gloss level to a water-based ink print that is equal to or greater than that of an oil-based ink print.

In recent years, due to pollution concerns, water-based inks using water or water and alcohol as solvents have been developed to replace oil-based inks that use petroleum-based solvents as solvents for solvent-based inks, and have been used in fields such as gravure, flexography, and screen printing. It has started to be used.

Water-based inks, which are virtually non-hazardous in terms of pollution, disaster prevention, and impact on the human body, are becoming popular very quickly. Water-based inks having such advantages are attracting attention not only in the ink industry but also in the paint industry. However, in the printing industry, water-based inks are rarely used despite their many advantages. Currently, most printing sites use conventional petroleum-based solvents by installing pollution prevention equipment, solvent recovery equipment, etc. In particular, for low-intermediate quality printable paper such as uncoated paper that is heavily soaked with ink, the quality difference between using oil-based ink and water-based ink is large, and the use of water-based ink is not considered at all. It has not been. The reasons why water-based ink is not used not only for low- and intermediate-quality printing paper but also for general printing paper are that it dries slowly, and its quality is lower than that of printed matter printed using oil-based ink. However, the biggest cause is poor quality, typified by lack of gloss and paper wrinkles due to lack of density. Particularly, ink seepage, which is seen on uncoated paper, reduces the gloss, to the point where the ink surface becomes less glossy than the paper itself. Attempts have been made to improve these drawbacks of water-based inks in the field of ink production, and improvements or modifications of water-soluble resins have been the main focus. The recent development of water solubility in alkyd type resins represents a peak. In oil-based inks or oxidation-based inks, alkyd resins have excellent durability and quality.
It also has a luster. Since this resin is the most commonly used in inks and paints, making this resin water-soluble has been the most desired. However, even if inks using alkyd type resins are used, in other words, despite improvements in ink manufacturing, there is still a much larger difference in the quality of printed matter compared to oil-based inks.

For example, Figure 1 shows water-based ink D (Aqua ink B-
169AQ1 Alcohol-free water-based ink manufactured by Toyo Ink Mfg. Co., Ltd.) and oil-based ink E (0G1BLl rotogravure ink manufactured by Toyo Ink Mfg. Co., Ltd.) showing changes in gloss depending on plate depth. The axis shows plate depth and the vertical axis shows gloss, but as is clear from this figure, in the case of water-based ink, the gloss decreases as the plate gets deeper and the amount of ink deposit increases. I can see that it is. In this way, it is unlikely that the quality of printed matter will be improved only by ink production, as long as water or water and alcohol are used as solvents. This difference in quality varies depending on the type of printing material, and the difference is even more pronounced for water-absorbing materials, such as non-coated paper such as plain gravure paper, cardstock/medium-weight paper, plain paper, newsprint, etc. As the density increases, the gloss decreases dramatically, and the difference becomes more pronounced as the density increases. Especially when printing with two or more colors, the gloss reduced by one color is 2
The result is that even if more than one color is printed, it does not increase. However, in reality, the printing materials used for printing such as flexo, screen, and gravure that can use these water-based inks are mainly uncoated paper, and the appropriate gloss is given to these printing materials depending on the density of the ink. This was previously impossible. In particular, there is no water-based ink that can replace the current oil-based ink, which produces high-quality printed matter even though uncoated paper is used, such as in gravure printing. The present invention completely solves the quality inferiority of printed matter, which is difficult to solve from the ink manufacturing perspective, from the standpoint of printing. It gives the printed image a gloss equal to or higher than that of ink, and at the same time improves print density and does not cause paper wrinkles.

That is, in the case of performing multicolor printing using water-based ink, the present invention applies pressure by pressing the printed image against a mirror surface with a press roll immediately after printing the first color, and if necessary, heats it to make it glossy. The second color and subsequent colors are printed without pressing to give the desired gloss.The more the ink builds up on the surface where the first color ink forms a film, the more the gloss increases. be. The present invention will be explained in more detail with reference to FIG. 2, which is one embodiment.
The sheet-shaped printing material 1 is unwound from the printing material roll 1' and passed between the printing cylinder P and the impression cylinder Q1 of the printing unit 5 for the first color, thereby applying the water-based ink 10 to the printing material 1 in a pattern. The first color is printed according to the shading.

The ink instantly penetrates into the surface layer of the printing material. After printing the first color, the printing side of the printing material 1 is placed on a mirror roll 3 and pressure is applied from the back side by a press roll 2. At this time, heat is applied from the mirror roll side as necessary. Press roll 2
Use hard rubber coated rolls, cotton rolls, woolen paper rolls, asbestos rolls, etc. The specular roll 3 is a roll with a heatable surface chrome plating, a polished cast steel roll, etc., but depending on the desired degree of gloss and patterning, the surface may have a satin finish or other special surface shape.

The printed matter passed between the mirror roll 3 and the press roll 2, was pressurized and dried, and then passed through the release roll 4 to the plate cylinder P2 and the impression cylinder Q.
2, a third printing unit consisting of plate cylinder P3, impression cylinder Q3, and a fourth printing unit consisting of plate cylinder P4 and impression cylinder Q4. take. It goes without saying that the printing medium is not limited to a roll-up type, but may also be a sheet type. The printed matter passes between the mirror roll 3 and the press roll 2 and is dried under pressure.The surface of the printed matter is flattened and sealed according to the shading of the image using resin in the ink. By creating a film that prevents water from penetrating, it prevents a decrease in gloss due to the transfer of water-based ink from the second color onward.

This effect is also confirmed by the fact that when water-based ink is printed on coated paper, it is possible to obtain a gloss level that is equal to or higher than that of conventional oil-based ink.

That is, if the image created by the first color water-based ink can maintain the same gloss as coated paper, there is no need to perform a glossing operation using a press after the second color overlaps the image. In multi-color printing, the problem is how the first and second colors of ink overlap, but with four-color tone patterns, by selecting an appropriate pattern plate for the first color, you can create a natural tone throughout the four colors. It can give the image a glossy shine. For example, in the case of a pattern such as a human face, by printing yellow or red as the first color, it is possible to give the printed matter a natural gloss even after four-color printing is completed. For example, as shown in FIG. 3, a graph is obtained when printing plate F as the first color with water-based ink, then applying gloss with a mirror roll, and measuring the gloss.
After that, red plate G was printed as the second color, eye plate H was printed as the third color, and black plate 1 was printed as the fourth color, and as is clear from the graph when the gloss was measured for each case, Once a polish is applied, there is no decrease in gloss even if no polish is applied after the second color; in fact, the gloss increases as more colors are applied. On the other hand, if no polishing is performed using water-based ink,
The fourth color is Ki version Fζ Red version G' and Eye version H' respectively.
, When printing with a sumi version V, the gloss decreases as the colors are added. In printed matter, it is absolutely necessary to provide gloss according to the density of printing, and the presence or absence of gloss greatly influences the visual evaluation of printed matter.

In the present invention, after the first color is printed, the printed material is given a gloss by pressing on a mirror roll, and the second and subsequent colors are printed simply by normal printing without any pressing.
Printed matter can be obtained that has a gloss equal to or higher than that of printed matter made with oil-based ink.

As described above, according to the present invention, it becomes possible to use water-based inks, which have not been widely used in the past because of their poor quality, especially lack of gloss, which has lowered the value of printed materials.

In addition, you only need to install one set of press roll and mirror roll (in most cases, the printing machine is equipped with a drying steam drum) in your current printing machine, and there is no need to strictly adjust the pressure. No special skill is required for this operation.

When performing the calender glossing method, which is conventionally used in paper manufacturing companies, it is necessary to uniformly calender the entire surface, and this requires extremely difficult techniques, but in the present invention, Since the water-based ink selectively prints only on the areas where the gloss has decreased, even if there is some unevenness in the device itself, it will be absorbed into the pattern, and the device can also use a very simple mechanism. .

Furthermore, since the process is carried out within the same mechanism as the printing machine, rewinding, storage, humidity control, and various other processes before and after printing can be omitted, and the gloss condition can be constantly monitored along with the printing operation. Next, examples of the present invention will be shown.

Example 1 Aqua ink B-169AQ, an alcohol-free water-based ink manufactured by Toyo Ink Mfg. Co., Ltd., was manufactured by Oji Paper Co., Ltd.
1501/Inch on non-coated Hokuto gravure paper
Immediately after printing the first color on a conventional gravure plate, a steam drum heater (steam pressure 31<9/Cf
il) was pressed onto a drum with mirror surface roll, and pressed from the back side with a press roll (linear pressure 58 kg/C).
ffL) After polishing, the second to fourth colors are printed, and the result is higher than normal printing using oil-based ink (0GBL1 book rotary printing ink manufactured by Toyo Ink Mfg. Co., Ltd.). A printed matter with a gloss of .

Note that the printing speed in this case was 100 m/min.
The results of measuring the gloss of the printed matter thus obtained are as shown in F-1 in FIG. In this case, the gloss was measured at 75° gloss using a gloss meter manufactured by Nippon Denshoku Kogyo Co., Ltd.

[Brief explanation of the drawing]

Fig. 1 is a graph showing changes in gloss depending on plate depth for oil-based ink and water-based ink when no glossing operation is performed, Fig. 2 is an explanatory diagram showing one embodiment of the present invention, and Fig. 3 is a graph showing changes in gloss of oil-based ink and water-based ink depending on plate depth. A graph showing changes in gloss due to overprinting. 1... Printing material, 1'-... Printing material roll, 2... Press roll, 3... Mirror roll, 4...・Release roll, 5...
First color printing unit, 6... Second color printing unit, 7... Third color printing unit, 8...
・Fourth color printing unit, 9... Winding roll,
10... Water-based ink, Pl, P2, P3, P4
...Plate cylinder, Ql, Q2, Q3, Q4...
・Impression cylinder.

Claims (1)

[Claims] 1. In a multicolor printing method using water-based ink, the first color is printed on the printing material, and immediately after that, it is pressed with a roll having a desired surface, and then normal printing is performed on the second and subsequent colors. A water-based ink printing method that gives gloss to printed matter.