JP2014166713A - Multicolor printing method for soft packaging resin film, printing apparatus for the same and multicolor print - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multicolor printing method for resin film which reduces production costs, decreases environmental problems and improves labor environments, and provides a high-quality multicolor print.SOLUTION: A method of multi-coloring a resin film A-1 executes white printing by a gravure or flexographic printing system and printing other than white by an ink jet printing system. The method reduces production costs of the plate cylinder necessary for gravure printing, decreases environmental problems and improves labor environments by minimizing the used amount of organic solvents and provides high-quality multicolor prints.

Description

  The present invention relates to a multicolor printing method, a printing apparatus, and a multicolor printed material for a resin film for soft packaging such as food and medicine.

Gravure printing is used for conventional full-color printing (multicolor printing) applied to resin films for soft packaging for foods and pharmaceuticals because of its high printing expression capability and high productivity.
This gravure printing is an intaglio, and an organic solvent is frequently used to lower the ink viscosity.

  In addition, the gravure printing plate is a chikuwa type with a hollow center, and a cylinder layer is provided on a cylindrical surface of aluminum or iron core. The surface is designed, and etching is performed by acid corrosion or physically by a diamond needle. The plate is made by a plate making method in which a chrome plating is applied to the entire surface of the plate cylinder provided with a recess in the cylinder layer and designed on the body layer.

Therefore, this plate making process requires a large number of raw materials and man-hours, and the time and cost of making the plate make a great burden on the price of the packaging material.
In particular, in the case of a product with a small lot, there is a problem that the plate making cost is higher than the product price.

  In addition, full-color printing by gravure printing is adopted in most of current full-color printing because of its high printing expression capability and productivity, but as described above, in the case of gravure printing, a large amount of organic matter is used to reduce the ink viscosity. Printing using a solvent. For this reason, in the printing process, the organic solvent is dried and discharged to the atmosphere, which causes problems such as air pollution, and is a heavy burden on workers working in the field, which is a problem in occupational safety and health.

  In recent years, the work quantity per lot of soft packaging materials for foods and pharmaceuticals has increased in proportion to small lots, and in reality, it has exceeded 50% of the total number of printing points. In addition, the plate making time and cost for the plate making process may take more than twice the product price, and the setup change time in gravure printing will take more than twice the actual printing time, which hinders productivity. It is a big burden on companies.

In order to solve or alleviate the problem of such gravure printing, a part of multi-color printing by an ink jet printing method that does not require a plate is used (Japanese Patent Laid-Open No. 11-115166).
However, inkjet printing is conventionally performed on paper, paperboard, metal plates and coated products.

Ink-jet printing inks include aqueous and non-aqueous (solvent and oil) solvent systems, and UV curable and solid types as solvent-free systems. These are selected according to the type of printed material and its application.
Conventionally, color printing is sometimes performed with water-based inkjet ink on a printed material such as paper or paperboard by an inkjet printing method, which enables high-speed printing by the ink solvent being absorbed by the printed material. .

However, since white uses the white color of a printing medium such as paper, white ink is not printed.
In addition, for proof printing, color printing including white using water-based ink may be performed by ink jet printing. However, the printing speed is very slow and the types of printed materials are limited, so that softening such as food is not possible. Not suitable for full-color printing on packaging resin films.

  The pigment used for the white ink is a glass or plastic bead having a size of 1 μm or less, the content is limited, the white hiding property is poor, and the commercial value as a printed matter of the soft packaging material is low.

Japanese Patent Laid-Open No. 11-115166

  The object of the present invention is to perform white color only in a gravure or flexographic printing method and color printing other than white color in an inkjet method in full-color printing (hereinafter referred to as “multicolor printing”) of a resin film for flexible packaging. It is to obtain a printing method, an apparatus thereof, and a printed matter capable of achieving a good finish for white, further reducing printing costs and improving productivity, and solving environmental problems and health problems of workers.

  In order to achieve the above object, according to the first aspect of the present invention, in the multicolor printing method of the resin film, white printing is performed by a gravure printing or flexographic printing method, and printing of colors other than white is performed by an ink jet method. It is a feature.

  The invention according to claim 2 is the multicolor printing method of the resin film for soft packaging according to claim 1, wherein in the multicolor printing method, gravure or flexographic printing is performed first, and then ink jet printing is performed. It is characterized by performing.

  The invention described in claim 3 is characterized in that, in the multicolor printing method of the resin film for soft packaging according to claim 1, the ink-jet printing is performed first and then the gravure or flexographic printing is performed. Is.

The invention according to claim 4 is the multicolor printing method of the resin film for soft packaging according to claim 1, wherein the gravure printing or flexographic printing uses water-based ink or non-toluene type oil-based ink. It is characterized by.
By using this water-based ink or non-toluene type oil-based ink, environmental problems can be further improved.

  The invention according to claim 5 is the method for multicolor printing of the resin film for soft packaging according to claim 1, wherein the ink for inkjet printing uses a UV curable ink. It is.

The invention according to claim 6 is the multicolor printing method for a resin film for flexible packaging according to claim 1 above, wherein the printed surface of the resin film is a surface by corona treatment, plasma treatment or flame treatment in advance. Processing is performed.
This invention enables high-quality printing.

The invention described in claim 7 is characterized in that in the multicolor printing method for a resin film for soft packaging according to claim 1, an overcoat is applied in advance to the printing surface of the resin film. It is.
Some films make it difficult to obtain the adhesion of ink jet ink, gravure ink, and flexo ink, and the adhesion between the film printing surface and these inks can be made possible. In particular, ink jet ink requires a very low ink viscosity due to its special printing method, so the selection of ink resin is greatly limited, so the ink jetting properties are sacrificed, and the adhesion to the film is sacrificed. This problem can be solved.

  The invention according to claim 8 is the method for multicolor printing of the resin film for soft packaging according to claim 1, wherein gravure or flexographic printing is performed off-line after the inkjet printing. It is.

  According to a ninth aspect of the present invention, there is provided a resin film multicolor printing apparatus comprising: a. An unwinding section for unwinding the resin film wound in a roll shape from the roll; b. An ink jet printing unit that prints colors other than white on the printing surface of the resin film unwound from the unwinding unit by an ink jet printing method; c. A gravure or flexographic printing unit that performs white printing on a printing surface of a resin film fed from the inkjet printing unit by a gravure or flexographic printing method; and d. And a winding unit for winding the resin film fed from the gravure or flexographic printing unit into a roll.

  According to a tenth aspect of the present invention, there is provided a resin film multicolor printing apparatus comprising: a. An unwinding section for unwinding the resin film wound in a roll shape from the roll; b. A surface treatment unit for surface-treating a printed surface of the resin film unwound from the unwinding unit; c. A precoat part for precoating the printed surface of the surface-treated resin film; d. An inkjet printing unit that prints a color other than white on the printing surface of the surface-treated and pre-coated resin film; e. A UV processing unit for UV-processing the inkjet printed surface; f. An intermediate feed unit for performing pattern matching between the inkjet printing and the printing by gravure printing performed later; g. A gravure or flexographic printing section for performing gravure printing on the printed surface of the resin film via the intermediate feed section using a water-based ink or a non-toluene type oil-based ink; h. A pattern control unit for detecting a shift between the gravure or flexographic printing and the ink-jet printing pattern and sending the shift information to the intermediate feed unit to match the pattern.

  The invention according to claim 11 is characterized in that, in a multi-color printed matter of a resin film, a white portion is printed by a gravure or flexographic printing method, and colors other than white are printed by an inkjet method. is there.

  As described above, in the multicolor printing of the resin film for soft packaging, the present invention is a combination of different printing techniques in which only white is performed by gravure printing or flexographic printing with excellent expression, and all other colors are performed by inkjet printing. As a result, the following effects can be obtained.

1. Since only white printing is performed by gravure or flexographic printing, the finish for white is good, and other than white is inkjet printing, so the cost and time required for plate making can be greatly reduced, and organic solvents that cause environmental and health problems Can be minimized.
2. All the colors other than white are ink jet printing, so it is possible to provide high-quality multicolor printing products.

Explanatory drawing of the multicolor printing method and apparatus according to the present invention

Inkjet printing on the resin film for soft packaging, which is the object of the present invention, requires that a high-speed printability be provided by using an installation type head instead of a shuttle type head. The stationary head employs a solvent-free UV curable ink that cures instantaneously because a high-speed printability cannot be obtained with a solvent-based ink in which the heads of the respective colors are close to each other and need to be dried.
There are very few precedents printed on transparent plastic films intended for soft packaging materials with UV curable inkjet inks. This is one of the reasons that printing of white ink is difficult with the ink jet printing method.

In order to make a print clear by printing the design on a transparent plastic film, it is necessary to perform white printing on the color design portion or the entire surface as a press for the color print design.
However, the white ink used in the UV curable ink jet printing system is difficult to print a white ink having a very low density as well as the density of the gravure ink due to the characteristics of the white pigment.

  If the white density of the design is low, the printed expression is poor and cannot be used as a product. This is because ink jet ink is ejected from a very small head nozzle having a pore diameter of several μm to several tens of μm, so it is stable unless the pigment content (several percent) is very low and the pigment particle size is small. Can not be injected. The gravure-printed white pigment is based on titanium oxide, its particle size is several μm, and the amount of pigment added is around 20%, but the inkjet nozzle diameter is from several μm to several tens of μm, and naturally the white pigment particle size is also quite large A small one is required, but if the particle size is small, the hiding property of white will be worsened and conflicting.

  Therefore, in the present invention, a printing method in which printing is performed by connecting an inkjet printing method and a gravure printing method or a flexographic printing method is adopted. This eliminates the need for plate making and printing setup change in the color printing section without degrading the printing quality, and allows the white density to be printed by a gravure printing method without using an organic solvent.

  However, printing different types of inkjet printing method and gravure printing method or flexographic printing method on the same line requires that the design of each color of the print design be matched with high accuracy, and this method of matching with high accuracy Has not been realized so far.

  However, in order to solve the object of the present invention as a suboptimal measure, instead of linking the inkjet printing method and the gravure printing method, printing the inkjet printing and the gravure printing method on separate lines to obtain a printed matter. Is also possible. However, since the white printing section can only print on the entire surface, the print design is limited, and the productivity is reduced as compared with the printing method connected on the same line. However, the printed matter and the flexible packaging material using the printed matter meet the object of the present invention.

  As a prior application, [Japanese Patent Laid-Open No. 11-2866161, Japanese Patent No. 29951936: Printing Method and Manufacturing Method of Packaging Resin Film Printed Body] In gravure printing of soft packaging material, a part of oil-based gravure printing is water-based A device has been proposed that replaces printing. In this method, a part of the color is replaced with a water-based gravure ink to remove the organic solvent, but the effect is small and limited. In addition, it is not possible to reduce the cost of plate making and improve the efficiency of setup change.

  Further, although [JP-A-11-115166: Inkjet printing system for rolled soft packaging material] has proposed a printing system in which gravure printing on a soft packaging material is replaced with an all-color inkjet printing system, an inkjet printing system has been proposed. The problem of the white density due to the ink (inkjet printing of white ink itself) has not been solved, and the printed expression of the printed matter is inferior, making commercialization difficult.

In contrast to these prior applications, the present invention solves the problem by a printing method in which an inkjet printing method and a gravure printing method or a flexographic printing method are connected.
In addition, in the present invention, in order to enable pattern matching of different types of printing methods, each apparatus of an intermediate film feed unit composed of an ink jet printing side film feed nip roll and a gravure printing side film nip roll, and a dancer roll is installed therebetween, An apparatus and method have been devised that enable highly precise control.

  The accuracy of pattern matching for each color in the normal design is usually about 0.2 to 0.5 mm of relief, but depending on the design, there is a design of hair removal that does not escape, so very high accuracy is required Is done. This accuracy is possible in the gravure printing method used for printing soft packaging materials, but it has been difficult to match the pattern with a completely different printing method on the same line to the plastic film extended by heat and tension. There is nothing. In the present invention, it is possible to stably and accurately control the film speed and tension of the ink jet printing unit and the gravure printing unit or the flexographic printing unit by using these apparatuses and control methods.

  Based on stable and highly accurate film control using this device and control method, marks for mark sensor detection are printed on the inkjet printing part for pattern matching, and the marks are detected by the mark sensor. By installing a device that controls the rotational speed, high-accuracy pattern matching is possible.

  The inkjet printing system and the gravure printing system are connected by a series of operations with these control devices, and the pattern matching is possible by adjusting the printing pitch of the inkjet printing pattern and the gravure printing pattern or the flexographic printing pattern with high accuracy. As a result, the white density can be ensured by the gravure printing method, and the productivity can be greatly improved by removing the organic solvent, reducing the plate-making cost, shortening the time for changing the printing setup, and reducing the printing quality.

An embodiment of the multicolor printing apparatus according to the present invention will be described below with reference to FIG.
First, the symbols will be described.

A: Print film unwinding part
A-1: Printing film
A-2: Film left and right ear end position control device

B: Film infeed section
B-1: Film infeed nip roll
B-2: Film printing surface treatment equipment

C: Inkjet printing section
C-1: Film printing surface pre-coating equipment
C-2: Each color inkjet head (K black, M red, C blue, Y yellow, etc.)
C-3: First UV irradiation lamp for curing each color inkjet ink
C-4: Second UV irradiation lamp for curing and fixing each color ink-jet ink
C-5: Chamber for storing UV irradiation lamp for nitrogen replacement
C-6: Nitrogen gas supply device

D: Film intermediate feed section
D-1: Middle film left and right ear edge position control device
D-2: Intermediate film feed nip roll for film transport from the inkjet section side
D-3: Dancer roll for film tension
D: 4: Intermediate feed nip roll for film transport to gravure
D-5: Inkjet printing pattern position mark sensor device

E: Gravure printing department
E-1: Gravure printing cylinder
E-2: Gravure white ink
E-3: Ink pan
E-4: Impression cylinder
E-5: Doctor blade
E-6: Drying box
E-7: Print image inspection device
E-8: Gravure pattern position mark sensor device

F: Film outfeed section
F-1: Film outfeed nip roll
F-2: Film outfeed dancer roll

G: Printed film winding section
G-1: Printed film.

The specifications of the printing apparatus described above and examples of the printing design will be described below.

・ Printing film: Biaxially stretched polyester film 12μm PET type manufactured by Unitika Co., Ltd. ・ Design: Color process color YMCK 4 colors, gravure white 1 color ・ Mark sensor: Color control mark of 5mm in width x 10mm in width by K (black) color printing

-Surface treatment method: 45 dyn / cm by corona discharge treatment
・ Pre-coat: Full surface coating by roll coating method (Cyan coupling agent coating)
Inkjet printing head: Piezo inkjet ejection head Konica Minolta IJ Co., Ltd. KM1800i
Inkjet ink: UV300 (urethane acrylate resin) manufactured by Sakata Inx Co., Ltd.

Inkjet dot density and ejection volume: 600 dpi, 13 picoliters / dot UV lamp: LED type UV irradiation lamp (main wavelength 385 nm) manufactured by Iwasaki Electric Co., Ltd.
・ Nitrogen substitution rate: Nitrogen substitution rate of 99.5% or more ・ Mark sensor control device: Color controller DP-2000 type color controller manufactured by Taiyo Electric Industry Co., Ltd.

-Gravure cylinder: design 1 pitch 220mm, plate circumference 660mm, surface length 700mm
・ Plate depth, number of lines: 28μ, 175 lines / inch ・ Ink type: Finestar 631 white (oil-based gravure ink) manufactured by Toyo Ink Co., Ltd.

・ Printing: printing width 600 mm (printing effective width 648 mm),
Compared with the conventional gravure printing method, the number of plate making has been reduced from 5 to 1 plate by 80%, and the setup time has been reduced by 90% from 90 minutes to 10 minutes, using organic solvents. The amount can be reduced by 70%.

  Next, a specific example of a printing method for performing printing by connecting an ink jet printing method and a gravure printing method to a soft packaging material such as food or medicine mainly composed of a plastic film will be described based on the reference numerals in FIG.

1. In the printing film unwinding part A, the resin film A-1 such as stretched polypropylene, stretched polyester, stretched nylon and the like wound in the roll shape of A-1 is unwound by the film left and right ear end position control device of A-2. The left and right positions are controlled and fed to the printing unit.

2. Next, the unwound film A1 is fed out to the printing section by the B-1 film infeed nip roll. At this time, surface treatment such as corona treatment, plasma treatment, flame treatment, etc. of B-2 is performed on the printing surface of the film A-1 in order to activate the film printing surface in order to increase the adhesive strength of the ink jet ink and the gravure ink. .

3. Next, pre-coat C-1 on the surface of film A-1 supplied to the inkjet printing section, and then for C-2 YMCK 4-color printing at least for process color printing to perform full color printing An inkjet head is provided, and a C-3 UV irradiation lamp is provided after each color inkjet head C-2.

This is provided in order to prevent printing defects from occurring due to mixing and interference of the inks of the respective colors when the overprinting is performed in a state where the ink-jet ink is not cured after printing each color.
Thereafter, the ink is completely cured by a C-4 multi-row UV irradiation lamp.
At this time, if the UV curable inkjet ink is cured in the air, some reactive groups react with oxygen in the air before the reactive groups of the UV curable ink react with each other due to oxygen in the air and cure. Curing stops halfway. This causes poor curing, resulting in a decrease in adhesive strength to the film and an irritating odor due to reactive groups in the ink.

  This is prevented by nitrogen replacement chambers and nitrogen supply devices for C-5 and C-6. The nitrogen supply device may use nitrogen filled in a cylinder in advance, but since it requires a running cost, initial investment is necessary, but a nitrogen generator may be introduced to supply nitrogen.

  The ink-jet head adopts an on-demand type based on a print design, not a continuous jet type. Among them, a method using a piezo ink jet method capable of stably ejecting ink is better for this purpose than a thermal ink jet method. The ink ejection density and amount are ejected from the ink nozzle hole at a density of 250 to 1200 dpi, and the ink ejection amount is several picoliters to several tens of picolits / dot. It is possible to adopt an appropriate head depending on the print design.

4). The film after inkjet printing is fed to the intermediate feed part D.
This intermediate feed portion D is devised to connect the inkjet printing method and the gravure printing method of the present invention. Usually, it is very difficult to connect different types of printing methods and combine them to express the design as a design, but this device makes it possible.

  First, the film feed speed of the D-2 inkjet side feed roll is used as the reference for the film feed speed of the entire machine, and all the film feed speeds are controlled by synchronizing or synchronizing with this speed. It is an invention that can be combined with the design of. Of course, YMCK colors of ink jet printing can also be matched by this method.

  The pattern alignment mark printed by inkjet printing (commonly known as the color contact mark) is detected by the D-5 mark sensor, and the pattern alignment mark printed by gravure printing is detected by the E-8 mark sensor. It is possible to match the designs of inkjet printing and gravure printing by controlling the rotation speed.

  In the present invention, the rotational speed of the gravure cylinder is controlled by the reference speed nip roll of D-2 and the mark sensor signal to enable high-precision pitch alignment printing of the ink-jet printing pattern and the gravure printing pattern.

  Conventional gravure pattern matching used a conventional method of moving dancer rolls, but this method is not suitable for this purpose because the pattern matching accuracy is poor and the adjustment speed is slow.

  The D-4 gravure feed nip roll and D-3 dancer roll control the tension of the inkjet printing section C and gravure printing section E to supply the film to the gravure cylinder section.

5. White gravure printing is performed on the inkjet printing film supplied by the intermediate feed unit, and after drying, the print inspection device is passed to the film outfeed unit.

  A pattern alignment mark (commonly known as a color contact mark) printed by inkjet printing is detected by the D-5 mark sensor, and the rotation speed of the gravure cylinder can be controlled by that signal to match the inkjet printing and gravure printing patterns. It is.

6). The film is fed to the take-up section by the F-1 outfeed nip roll and the F-2 outfeed dancer roll in the outfilm feed section.

7). The fed G-1 printed film is wound up by a winder. By repeating this series of operations, a printing method in which an ink jet printing method and a gravure printing method are connected can be made possible.

A: Print film unwinding part
A-1: Printing film
A-2: Film left and right ear end position control device B: Film infeed section
B-1: Film infeed nip roll
B-2: Film printing surface treatment device C: Inkjet printing section
C-1: Film printing surface pre-coating equipment
C-2: Each color inkjet head (K black, M red, C blue, Y yellow, etc.)
C-3: First UV irradiation lamp for curing each color inkjet ink
C-4: Second UV irradiation lamp for curing and fixing each color ink-jet ink
C-5: Chamber for storing UV irradiation lamp for nitrogen replacement D: Film intermediate feed section
D-1: Middle film left and right ear edge position control device
D-2: Intermediate film feed nip roll for film transport from the inkjet section side
D-3: Dancer roll for film tension
D: 4: Intermediate feed nip roll for film transport to gravure
D-5: Inkjet printing pattern position mark sensor device
D-6: Nitrogen gas supply device E: Gravure printing section
E-1: Gravure printing cylinder
E-2: Gravure white ink
E-3: Ink pan
E-4: Impression cylinder
E-5: Doctor blade
E-6: Drying box
E-7: Print image inspection device F: Film outfeed section
F-1: Film outfeed nip roll
f-2: Film outfeed dancer roll G: Printed film winding part
G-1: Printed film

Claims (11)

  A method for multicolor printing of a resin film, wherein white printing is performed by gravure printing or flexographic printing, and printing of colors other than white is performed by ink jet printing.   2. The method for multicolor printing of a resin film according to claim 1, wherein in the multicolor printing method, gravure or flexographic printing is performed first, and then ink jet printing is performed.   2. The method for multicolor printing of a resin film according to claim 1, wherein in the multicolor printing method, inkjet printing is performed first, followed by gravure or flexographic printing.   The method for multicolor printing of a resin film according to claim 1, wherein water-based ink or non-toluene type oil-based ink is used for the gravure printing or flexographic printing.   The resin film multicolor printing method according to claim 1, wherein a UV curable ink is used for the ink jet printing ink.   2. The resin film multicolor printing method according to claim 1, wherein the printing surface of the resin film is subjected to surface treatment by corona treatment, plasma treatment or flame treatment in advance. 2. The resin film multicolor printing method according to claim 1, wherein an overcoat is applied in advance to the printing surface of the resin film.   The multicolor printing method for a resin film according to claim 1, wherein gravure or flexographic printing is performed offline after the inkjet printing. a. An unwinding section for unwinding the resin film wound in a roll shape from the roll;
b. An ink-jet printing unit that prints colors other than white on the printing surface of the resin film unwound from the unwinding unit;
c. A gravure or flexographic printing unit that performs white printing on a printing surface of a resin film sent out from the inkjet printing unit by a gravure or flexographic printing method;
d. A winding unit for winding the resin film fed from the gravure or flexographic printing unit into a roll; and
e. A multicolor printing apparatus for resin films. a. An unwinding section for unwinding the resin film wound in a roll shape from the roll;
b. A surface treatment portion for surface-treating the printed surface of the resin film unwound from the unwinding portion;
c. A precoat part for precoating the printed surface of the surface-treated resin film;
d. An inkjet printing unit that prints colors other than white on the printing surface of the surface-treated and pre-coated resin film;
e. A UV processing unit for irradiating the inkjet printed surface with UV;
f. An intermediate feed unit for pattern matching of printing by the inkjet printing and gravure printing performed later;
g. A gravure or flexographic printing part that performs gravure printing using a water-based ink or a non-toluene type oil-based ink on the printing surface of the resin film via the intermediate feed part;
h. A pattern control unit for detecting a shift of the pattern of the gravure or flexographic printing and the inkjet printing, and sending the shift information to the intermediate feed unit to match the pattern;
i. A multicolor printing apparatus for resin films. A multi-color printed matter of a resin film in which a white portion is printed by a gravure or flexographic printing method and colors other than white are printed by an inkjet method.

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