JPH10324896A - Cleaning solution - Google Patents

Abstract

(57) [Problem] To provide a cleaning liquid which has high cleaning efficiency, is inexpensive, and does not damage the surface such as a gravure plate surface. A cleaning solution comprising starch powder mixed with a solvent that does not dissolve starch powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of gravure printing or the technical field of cleaning. In particular, the present invention relates to a cleaning liquid for removing ink stains on a printing plate after printing in gravure printing.

[0002]

2. Description of the Related Art In gravure printing, after ink is supplied to a printing plate and unnecessary ink is scraped off by a doctor blade, the ink is transferred to printing paper (printing film) pressed on the printing plate to perform printing. . The gravure plate used in printing and stained with ink is washed and the ink stain is removed in order to resume printing, store it, or reproduce it as a new plate.

[0003]

Several types of cleaning liquids are used for cleaning a gravure plate. For example, trichloroethylene, tetrachloroethylene (perchloroethylene), 111-trichloroethane, and dichloromethane (methylene chloride) have been used as cleaning liquids, but are currently not used because they are subject to legal regulations due to environmental problems of destruction of the ozone layer. Further, sodium bicarbonate (sodium bicarbonate: N) which is a monoclinic fine crystal is used.
aHCO ₃ ) mixed with water in a proportion higher than the solubility is used as a washing liquid. However, agglomerated particles are generated, and the particle size is large and cannot fit inside the cells of the gravure plate, and the cleaning efficiency is not sufficient. It is also expensive. Abrasives are used for cleaning (blast cleaning, brush cleaning). General abrasives such as silicon carbide, fused oxide oxide, and glass beads have high hardness and easily damage the gravure plate surface. Therefore, plastic abrasives such as nylon and polycarbonate having low hardness are used, but the gravure plate surface is still damaged.

Accordingly, an object of the present invention is to provide a high cleaning efficiency,
An object of the present invention is to provide a cleaning solution which is inexpensive and does not damage the surface such as a gravure plate surface.

[0005]

The above objects are achieved by the present invention described below. That is, the present invention is a “cleaning liquid obtained by mixing starch powder with a solvent that does not dissolve starch powder”. According to the present invention, starch powder acts as an abrasive, and starch powder is inexpensive and has low hardness.
Accordingly, a cleaning liquid having high cleaning efficiency, being inexpensive, and not damaging the surface such as the gravure plate surface is provided. The present invention also provides a cleaning solution for cleaning a gravure plate surface,
The solvent is a cleaning liquid which is a solvent that dissolves gravure ink stains. According to the present invention, a cleaning liquid having high cleaning efficiency for a gravure plate is provided. Further, the present invention relates to “the starch powder 5 to 100 parts by weight of the solvent”.
20 parts by weight ". According to the present invention, the cleaning liquid has appropriate flow characteristics, is easy to handle, and has high cleaning efficiency. The present invention is also a "cleaning liquid having a mode of 10 to 30 [mu] m in the frequency distribution of the particle size of the starch powder". ADVANTAGE OF THE INVENTION According to this invention, sufficient washing | cleaning efficiency is acquired because starch powder enters into the inside of the cell of a gravure plate. The present invention is also directed to "a cleaning solution wherein the solvent is any one of toluene, methyl ethyl ketone, ethyl acetate, and methyl cellosolve, or a mixed solvent of two or more types." According to the present invention,
It has excellent solubility in general gravure ink stains, has high cleaning efficiency, and can be used widely.

[0006]

Next, the present invention will be described by way of embodiments. Before describing the cleaning liquid, a brief description will be given of the shape of the plate surface of a gravure plate, which is a typical example of a cleaning target. The plate surface has regularly arranged concave portions called cells. Printing is performed by transferring the ink filled in the cells to printing paper (printing film). Therefore, the amount of ink to be filled varies depending on the cell volume, and the amount of ink transferred to the printing paper (printing film) also varies. In other words, by changing the volume of the cell, it is possible to give a print a shade of a picture.

FIG. 1 is a diagram showing the shape of a cell formed on the plate surface of a gravure plate (the upper diagram shows a cross section, and the lower diagram shows an upper surface). In FIG. 1, 1a, 1b, 1c, and 1d are embankments,
2a, 2b, 2c, 2d are cell bottoms, 3a, 3b, 3
c and 3d are top views of the cell. (A)-(D) of FIG.
As shown in the example, the shape of the cell differs depending on the method of manufacturing the gravure plate.

In a gravure print, a picture is reproduced by a set of halftone dots corresponding to cells. In order to express the fineness of a halftone dot, the number of halftone dots arranged in one inch is generally used. For example, when 150 halftone dots are arranged in one inch, it is expressed as 150 lines. In gravure printing, usually 100 to 200 lines are used. Therefore, in the shape of the cell shown in FIG. 1, the cell has a dimension in which 100 to 200 cells are regularly arranged in one inch, that is, a dimension of 250 μm to 125 μm. The maximum depth of the cell corresponding to the maximum density portion of the picture differs depending on the number of lines, and is about 60 μm to 40 μm.

Next, the cleaning liquid of the present invention, in which the above-described gravure plate is a representative example of the object to be cleaned, will be described. As starch powder, starch powder produced from potato, sweet potato, corn, wheat, etc. can be used. As for the particle size of the starch powder, the mode in the frequency distribution is 1
The thickness should be 0 to 30 μm. By using starch powder having this particle size for the cleaning liquid, the starch powder enters every corner inside the cells of the gravure plate and acts as an abrasive, so that sufficient cleaning efficiency can be obtained. Since the starch powder has a low hardness, it does not hurt even if the chrome-plated surface is a copper gravure plate. Further, industrial products containing starch powder as a main component as described above, for example, an anti-blocking material and the like can be used.

As the solvent, water or an organic solvent can be used. In the case of water, water alone may be used, but the cleaning effect can be enhanced as an aqueous solution of a surfactant, a detergent, or the like. In addition, a mixed solution containing water as a main component and an organic solvent (eg, alcohols) soluble in water can be used. When a solvent containing a large amount of water is used, gelatinization of starch should be avoided. For example, as the starch powder, a starch powder of a grade having a large ratio of β-starch and a small ratio of α-starch is used, and the water temperature is 50 ° C or lower, preferably 30 ° C or lower.

Examples of the organic solvent include methyl acetate, acetone, ethyl acetate, methyl ethyl ketone, isopropyl acetate, methyl alcohol, isopropyl alcohol, ethyl alcohol, toluene, sec-butyl acetate, isobutyl acetate, sec-butyl alcohol, n-butyl acetate, and isobutyl. Alcohol, xylene, methyl cellosolve, n-butyl alcohol, cellosolve, cyclohexane, cellosolve acetate, diacetone alcohol, butyl cellosolve, cyclohexanol, and the like can be used as a single solvent or a mixed solvent.

Gravure inks vary depending on the printing target (book paper, wrapping paper, paper containers, synthetic paper, cellophane, plastic film, metal foil, titanium paper, vinyl chloride sheet, etc.), and according to the ink composition. Solvent is used. Solvents suitable for the cleaning liquid of the present invention are true solvents having high solubility of the ink. Of course, a solvent other than the true solvent can be mixed in order to adjust the cleaning liquid to another suitable property, for example, the drying speed. In particular, a simple or mixed solvent of ethyl acetate, methyl ethyl ketone, toluene, and methyl cellosolve has excellent solubility in general gravure ink stains and can be used widely.

[0013]

【Example】

(Washing target) The printing surface of the gravure plate, which is used for printing with the ink for building materials of vinyl chloride film and where the dried ink stain remains, is to be washed. The cells formed on the plate are 150
The line has a depth of 50 μm and has an inverted pyramid shape substantially similar to that of FIG. The surface is a copper surface without chrome plating. (Cleaning liquid) In the following composition, a starch powder was mixed with a solvent and stirred for about 5 minutes by a hand mixer (a stirring device in which the blades were rotated by a motor) to obtain a cleaning liquid. Ethyl acetate 100 parts by weight Methyl ethyl ketone 100 parts by weight Toluene 100 parts by weight Starch powder (anti-blocking material) 50 parts by weight A washing solution was obtained. Ethyl acetate 100 parts by weight Methyl ethyl ketone 100 parts by weight Toluene 100 parts by weight (Washing method) A cleaning solution or a comparative cleaning solution is contained in a waste cloth, and the plate surface is manually rubbed to remove dirt. A gravure plate is set in a cleaning device having a oscillating brush, and a cleaning liquid or a comparative cleaning liquid is jetted from an injection nozzle almost at the same time as the start of oscillating to remove dirt. (Results of cleaning) The results shown in Table 1 below were obtained, and the cleaning solution of the present invention is clearly superior in cleaning effect as compared with the comparative cleaning solution.

[Table 1]

[0014]

As described above, according to the present invention, there is provided a cleaning liquid which has high cleaning efficiency, is inexpensive, and does not damage the surface such as a gravure plate surface. Further, according to the present invention, in which the solvent is a solvent that dissolves gravure ink stains, a cleaning liquid for a gravure plate is provided. Further, according to the present invention, which is obtained by mixing 5 to 20 parts by weight of starch powder with respect to 100 parts by weight of a solvent, the cleaning liquid has appropriate flow characteristics, is easy to handle, and has high cleaning efficiency. According to the present invention, in which the mode is 10 to 30 μm in the frequency distribution of the particle size of the starch powder, sufficient cleaning efficiency can be obtained because the starch powder enters the inside of the cell of the gravure plate. According to the present invention, the solvent is any one of toluene, methyl ethyl ketone, ethyl acetate, and methyl cellosolve, or a mixed solvent of two or more thereof. Is high and can be used widely.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a plate surface of a gravure plate.

[Explanation of symbols]

 1a, 1b, 1c, 1d Bank part 2a, 2b, 2c, 2d Cell bottom part 3a, 3b, 3c, 3d Cell top view

Claims (5)

[Claims] 1. A cleaning liquid characterized by mixing starch powder with a solvent that does not dissolve starch powder. 2. The cleaning liquid according to claim 1, wherein the cleaning liquid is a cleaning liquid for cleaning a plate surface of a gravure plate, wherein the solvent is a solvent that dissolves gravure ink stains. 3. The cleaning solution according to claim 1, wherein 5 to 20 parts by weight of said starch powder is mixed with 100 parts by weight of said solvent. 4. The cleaning liquid according to claim 1, wherein a mode of the frequency distribution of the particle size of the starch powder is 10 to 30 μm. 5. The cleaning solution according to claim 1, wherein the solvent is any one of toluene, methyl ethyl ketone, ethyl acetate, and methyl cellosolve, or a mixed solvent of two or more thereof.