JP6162535B2 - Gravure printing method - Google Patents

Description

The present invention is a gravure printing method capable of maintaining good storage stability of an ink composition for organic solvent-based gravure printing until printing, preventing static electricity generation during printing, and continuously maintaining cell reproducibility. About.

In the packaging of food, confectionery, household goods, plastic bottles, etc., packaging materials using various plastic films are widely used because of functions such as designability, economy, contents protection, and transportability. Also, many packaging materials have surface gravure printing (printed only on the front side of the adherend of ink and contacted with foods, etc.) in order to impart design and message properties to appeal to consumers. No printing is performed on the back side), and reverse gravure printing (printing on the back surface of the ink adherend and laminating a film on the printing surface) is performed.

In recent years, the printing speed has been increased to improve productivity, and static electricity is generated due to friction between the printing film and the rolls of the printing press, and the resulting whiskers (the ink in a whisker shape from the printing part to the non-printing part). Problems such as printing that protrudes and misting (a phenomenon in which ink splatters and contaminates the printed matter) occur. Further, when the printing speed is increased, the doctor cuts worse, and plate fog (a phenomenon in which ink adheres to the non-image area of the printing plate in a thin film state) occurs.

Static electricity is generated by friction between a material that is likely to generate a positive charge and a material that is likely to generate a negative charge. At that time, in an environment where the atmosphere contains a lot of moisture (high humidity), static electricity is discharged in the atmosphere, so the amount of stored static electricity (charge amount) is also reduced. I can say that. Recently, the printing environment has been controlled to some extent by air conditioning equipment, and there is almost no printing under extremely high or low humidity. However, if the air is still dry in winter, the amount of charge such as plastic film is large. Become.

On the other hand, since organic solvent ink has high insulation, when printed on a charged plastic film or the like, it is easily affected by static electricity because it is less likely to discharge. And especially in winter when the air is dry, the above-mentioned printed matter is liable to appear. Therefore, in order to alleviate the influence of static electricity on the ink, measures for preventing static electricity have been taken so far from both the apparatus and the ink composition side.

For example, as a countermeasure against static electricity from the ink composition side, a technique (for example, see Patent Document 1) containing an antistatic agent is disclosed in advance.
However, since the antistatic agent is expensive as a material for the ink composition, it cannot be denied that it is economically disadvantageous. Furthermore, if an antistatic agent is contained in advance, there arises a problem that the storage stability of the ink is lowered.

JP 2005-290082 A

Therefore, the problems to be solved by the present invention are to maintain the storage stability of the organic solvent-based gravure printing ink composition until printing, to alleviate printing defects due to static electricity during printing, and It is an object to provide a gravure printing method excellent in economic efficiency, capable of continuously maintaining the prevention of cell and cell reproducibility.

In order to solve the above-mentioned problems, the present inventors firstly include water in an organic solvent-based gravure printing ink composition (hereinafter also simply referred to as an ink composition) so as not to cause an economic disadvantage. Therefore, we investigated a method to reduce the insulation and suppress the influence of static electricity. That is, in order to suppress the influence of static electricity in the ink composition, a method of printing in a state where water is always included in the ink composition was studied.

However, depending on the combination of materials that make up the organic solvent-based gravure printing ink composition, when water is added directly to the organic solvent-based gravure printing ink composition, it may be caused by changes in the solubility of the binder resin In some cases, the resin and pigments may be agglomerated and fluidity may be lowered. In the present invention, even if water is added before printing, such a phenomenon does not occur. Therefore, by adding water before printing and / or diluting with an organic solvent containing water diluted during printing. A method of suppressing the influence of static electricity by always printing in a state in which water is contained in the ink composition while diluting the ink composition with a diluting solvent containing water by containing a predetermined amount of water. I found it. As a result of intensive studies based on the above technical concept, the present inventors have developed a gravure printing method that solves all of the above problems and completed the present invention.

That is, the present invention is a gravure printing method using an organic solvent-based gravure printing ink composition containing a pigment, a binder resin, and an organic solvent, wherein the binder resin is isopropyl alcohol tolerance of the following condition 1 The polyurethane resin satisfying the requirement is less than 30% by mass, and printing is performed while maintaining the range in which the content of water in the organic solvent-based gravure printing ink composition is 0.1 to 5% by mass. This is a gravure printing method.
<Condition 1> With respect to a polyurethane resin solution having a liquid temperature of 25 ° C. obtained by dissolving 2.5 g of a polyurethane resin in a mixed organic solvent composed of 6.0 g of ethyl isopropyl alcohol tolerance and 1.5 g of isopropyl alcohol, When isopropyl alcohol having a liquid temperature of 25 ° C. is added and the amount of isopropyl alcohol added until the polyurethane resin solution transitions from transparent to translucent is X (g), X satisfies 25 g or less. .

The present invention also provides the above organic solvent-based gravure printing ink at the time of printing by diluting the above-mentioned organic solvent-based gravure printing ink composition using a dilution solvent containing 0.2 to 10% by mass of water. It is preferable to maintain the water content in the composition at 0.1 to 5% by mass.
In the present invention, the dilution solvent is a mixed solvent of an ester organic solvent, an alcohol organic solvent, and water, and a mixing ratio of the ester organic solvent and the alcohol organic solvent is a mass ratio. The organic solvent / alcohol-based organic solvent is preferably in the range of 50/50 to 95/5.
Hereinafter, the gravure printing method of the present invention will be specifically described.

First, the effect of suppressing the influence of static electricity by incorporating water in the organic solvent-based gravure printing ink composition will be described.
Since the organic solvent-based ink composition has high insulation, there is no factor (such as discharge into the air) that weakens static electricity while the ink composition is printed, and it is affected as it is. On the other hand, when an appropriate amount of water is present in the ink composition, the ink composition itself has an action of lowering the insulating property, which is considered to be an effect of suppressing the influence of static electricity. Further, when water is evaporated from the ink composition and an air layer containing a large amount of water vapor is formed in the vicinity of the printing surface, it is considered that the discharge property is increased and the amount of static electricity (charge amount) can be reduced. And it is estimated that these synergistic effects can suppress the influence of static electricity in the ink composition as a result.
The technique for adding water to the organic solvent-based ink composition is disclosed in Japanese Patent Application Laid-Open No. 09-328646, etc., but the idea of the present invention is completely different from such a technique.
First, the technology disclosed in Japanese Patent Application Laid-Open No. 09-328646 is intended to improve the cell reproducibility of the highlight portion in an ink system that minimizes the use of an aromatic solvent and suppresses the influence of static electricity. Does not exist anywhere.

Even if the organic solvent-based ink composition described in the publication has the effect of suppressing the influence of static electricity when printing is started, the effect will eventually be achieved during long-term printing due to the following reasons. It will be lost.
In gravure printing, the gravure plate is immersed in a container filled with the ink composition and rotated, and the ink composition adhering to the area other than the image area is scraped off with a doctor blade, and only the ink composition in the image area is transferred to the printing medium for printing. It is a method to do. Therefore, the organic solvent evaporates from the ink composition container or while the excess ink composition is scraped off by the doctor blade, and the viscosity of the concentrated ink increases, making it unsuitable for printing conditions. Accordingly, a diluent for the evaporated organic solvent (an organic solvent for diluting the concentrated ink composition) is added later, and printing is performed while maintaining an appropriate viscosity as the ink composition.

However, during long-term printing, not only the organic solvent but also water evaporates together and only the components contained in the diluent are replenished. For example, in the above-mentioned Japanese Patent Application Laid-Open No. 09-328646, as shown in Table 1 of paragraph [0030], the diluted solvent does not contain any water. Therefore, when printing is performed for a long time, all of the water evaporates, and the influence of static electricity cannot be suppressed from the technique described in the publication. That is, it can be said that there is no technology that uses water to suppress the influence of static electricity in the ink composition over a long period of printing.
Incidentally, when the ink composition at the start of printing contains a large amount of water, the consumed ink composition is replenished before the water that causes the above effect to evaporate is evaporated. If the printing conditions are such that water is also replenished, the effect of suppressing the influence of static electricity in the ink composition may be maintained even during long-term printing.
However, there are many printed designs in which almost no ink composition is consumed and only the diluent is replenished. It is extremely difficult to contain a large amount of water in the ink composition from the start of printing, so that it can be applied to the ink composition used for such printing patterns.
On the other hand, the present invention is a method of always containing an amount of water that can suppress the influence of static electricity in an organic solvent-based gravure printing ink composition. Specifically, since it is a method of performing printing while maintaining the water content in the organic solvent gravure printing ink composition at 0.1 to 5% by mass at all times, the printing pattern as described above is used. Even if printing is performed for a long time or even when water is evaporated, the influence of static electricity on the organic solvent-based gravure printing ink composition can be suppressed.

Next, the organic solvent-based gravure printing ink composition used in the gravure printing method of the present invention will be described.
The ink composition for organic solvent-based gravure printing used in the gravure printing method of the present invention contains a pigment, a binder resin, and an organic solvent.

The ink composition for organic solvent-based gravure printing used in the gravure printing method of the present invention contains a pigment.
The pigment is not particularly limited, and organic, inorganic, or extender pigments that can be used in organic solvent-based gravure printing ink compositions can be used.
Specifically, examples of the inorganic pigment include titanium oxide, bengara, antimony red, cadmium yellow, cobalt blue, bitumen, ultramarine blue, carbon black, and graphite. Examples of the organic pigment include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments. Furthermore, examples of extender pigments include calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc.
The content of these pigments in the organic solvent gravure printing ink composition is usually preferably in the range of 1 to 50% by mass. When the content of the pigment in the ink composition for organic solvent-based gravure printing is less than 1% by mass, a printed matter having a sufficient printing density may not be obtained. On the other hand, when the content of the pigment in the organic solvent-based gravure printing ink composition exceeds 50% by mass, the viscosity may be too high.

The ink composition for organic solvent-based gravure printing used in the gravure printing method of the present invention contains a binder resin.
Examples of the binder resin include polyurethane resins, polyamide resins, vinyl chloride-vinyl acetate copolymer resins, chlorinated polypropylene resins, ethylene-vinyl acetate, which are conventionally used in organic solvent-based gravure printing ink compositions. Copolymer resin, vinyl acetate resin, nitrocellulose resin, acrylic resin, polyester resin, alkyd resin, polyvinyl chloride resin, rosin resin, rosin modified maleic acid resin, ketone resin, cyclized rubber, chlorinated rubber, butyral resin, Petroleum resin and the like can be used alone or in combination of two or more.

Examples of the polyurethane resin include a polyurethane resin that does not satisfy the isopropyl alcohol tolerance of the following condition 1 and a polyurethane resin that satisfies the isopropyl alcohol tolerance of the following condition 1. In addition, the polyurethane resin which satisfies the isopropyl alcohol tolerance of the following conditions 1 is less than 30 mass% in binder resin.
<Condition 1> With respect to a polyurethane resin solution having a liquid temperature of 25 ° C. obtained by dissolving 2.5 g of a polyurethane resin in a mixed organic solvent composed of 6.0 g of ethyl isopropyl alcohol tolerance and 1.5 g of isopropyl alcohol, When isopropyl alcohol having a liquid temperature of 25 ° C. is added and the amount of isopropyl alcohol added until the polyurethane resin solution transitions from transparent to translucent is X (g), X satisfies 25 g or less. .
The transparent means that the polyurethane resin is completely dissolved, and the translucent means that the polyurethane resin is not dissolved.
In addition, about the polyurethane resin when a polyurethane resin solution exhibits a translucent state even if it does not add the said polyurethane resin and isopropyl alcohol, A is set to 0g and it is contained in the category of the isopropyl alcohol tolerance of the conditions 1.
When the content of the polyurethane resin satisfying the above condition 1 is less than 30% by mass in the binder resin, the solubility of the binder resin is improved when water is directly added to the ink composition for organic solvent gravure printing. Changes will not occur.

As a specific example of the polyurethane resin satisfying the above condition 1, a urethane prepolymer is synthesized by a reaction between an organic diisocyanate compound and a polymer diol compound, and a chain extender and a reaction terminator are reacted as necessary. A polyurethane resin satisfying the above condition 1 can be used.
Examples of the organic diisocyanate compound include aromatic diisocyanate compounds such as tolylene diisocyanate, alicyclic diisocyanate compounds such as 1,4-cyclohexane diisocyanate and isophorone diisocyanate, aliphatic diisocyanate compounds such as hexamethylene diisocyanate, and α, α, Aro-aliphatic diisocyanate compounds such as α ′, α′-tetramethylxylylene diisocyanate can be used alone or in admixture of two or more.

Examples of the polymer diol compound include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyether diol compounds such as alkylene oxide adducts such as ethylene oxide and propylene oxide of bisphenol A, adipic acid, sebacic acid, phthalic anhydride, etc. 1 type or 2 or more types of dibasic acid of these, and 1 type or 2 types of glycols, such as ethylene glycol, propylene glycol, 1, 4- butanediol, neopentyl glycol, 3-methyl-1, 5-pentanediol Various polymer diol compounds such as polyester diols such as polyester diols and polycaprolactone diols obtained by condensation reaction with the above can be used alone or in combination of two or more. Furthermore, in addition to the above polymer diol compounds, alkane diols such as 1,4-pentanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, ethylene glycol, propylene glycol, 1,4- Low molecular diol compounds such as butanediol and 1,3-butanediol can be used alone or in combination of two or more.

The organic diisocyanate compound and the polymer diol compound are used in an equivalent ratio of isocyanate group: hydroxyl group (isocyanate index) of usually 1.2: 1.0 to 3.0: 1.0, preferably 1. .3: 1.0 to 2.0: 1.0. When the above isocyanate index is smaller than 1.2, it tends to be a flexible polyurethane resin. When the blocking resistance is low when printing ink, it may be preferable to use it together with other hard resin. is there.

As the chain extender, known chain extenders used in polyurethane resins as ink binders can be used. Aliphatic diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, hexamethylenediamine, and isophoronediamine. , Cycloaliphatic diamines such as 4,4'-dicyclohexylmethanediamine, aromatic diamines such as toluylenediamine, araliphatic diamines such as xylenediamine, N- (2-hydroxyethyl) ethylenediamine, N- ( 2-hydroxyethyl) propylenediamine, diamines having a hydroxyl group such as N, N′-di (2-hydroxyethyl) ethylenediamine, ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, A diol compound such as reethylene glycol can be exemplified.
Furthermore, polyamines such as diethylenetriamine and triethylenetetramine can be used in combination as long as the polyurethane resin does not gel.

As the reaction terminator, known reaction terminators used in polyurethane resins as ink binders can be used, monoalkylamines such as n-propylamine and n-butylamine, di-n-butylamine and the like. And alkanolamines such as monoethanolamine and diethanolamine, and monoalcohols such as ethanol.

A known polyurethane resin production method can be used as it is, using a polyurethane resin satisfying the above condition 1 and the above materials. Moreover, since the above-mentioned isopropyl alcohol tolerance will change if the molecular weight of each component, chemical structure, and equivalence ratio differ, these components are combined suitably.
The weight average molecular weight of the polyurethane resin satisfying the above condition 1 is 10,000 to 70,000.

The content of the binder resin in the ink composition for organic solvent gravure printing is usually preferably in the range of 1 to 30% by mass. When the content of the binder resin in the organic solvent-based gravure printing ink composition is less than 1% by mass, the pigment dispersibility may be lowered. On the other hand, when the content of the binder resin in the organic solvent-based gravure printing ink composition exceeds 30% by mass, the viscosity of the ink composition increases.

The ink composition for organic solvent-based gravure printing used in the gravure printing method of the present invention contains an organic solvent.
Examples of the organic solvent include ketone organic solvents (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), ester organic solvents (methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, isobutyl acetate, etc.) Alcohol organic solvents (for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, butyl alcohol, etc.) and hydrocarbon organic solvents (toluene, methylcyclohexane, etc.) can be used. It is preferable to use an ester organic solvent and an alcohol organic solvent in combination in consideration of recent environmental problems and the printability and drying properties of the ink composition. Furthermore, it is preferable to contain 5 mass% or more of propyl acetate as said ester solvent from the point of printability.

The organic solvent-based gravure printing ink composition used in the gravure printing method of the present invention may further contain a pigment dispersant, tackifier, crosslinking agent, lubricant, anti-blocking agent, surfactant and the like. . Moreover, it is also possible to add water in the range in which the storage stability of the organic solvent gravure printing ink composition does not deteriorate.

The ink composition for organic solvent-based gravure printing used in the gravure printing method of the present invention can be produced by using various dispersing / kneading apparatuses generally used for the above various materials.

In the present invention, the range in which the water content is 0.1 to 5% by mass is maintained during gravure printing using the ink composition for organic solvent gravure printing.
The water content at the time of printing means the content of water with respect to the ink composition for organic solvent gravure printing at the time of printing.
When the water content of the organic solvent-based gravure printing ink composition at the time of printing is less than 0.1% by mass, the antistatic property may be lowered. On the other hand, if the water content of the organic solvent-based gravure printing ink composition during printing exceeds 5% by mass, the resin or pigment aggregates and the fluidity of the organic solvent-based gravure printing ink composition decreases. Sometimes.
The dilution solvent containing water is composed of water and the organic solvent, and the water content is preferably 0.2 to 10% by mass, more preferably 0.3 to 5% by mass. preferable.

In consideration of recent environmental problems and printability and drying properties of the ink composition, the water-containing dilution solvent is an ester organic solvent, an alcohol organic solvent, and a mixed solvent of water. The mixing ratio of the ester organic solvent and the alcohol organic solvent is preferably in the range of mass ratio of ester organic solvent / alcohol organic solvent = 50/50 to 95/5. Furthermore, it is preferable to contain 5 mass% or more of propyl acetate as said ester solvent from the point of printability. By using a dilution solvent containing water, the fluidity of the ink composition for organic solvent gravure printing and the aggregation of resins and pigments, which may be caused by a rapid change in the solubility of the binder resin, are considered. Can be prevented.

Next, the gravure printing method using the organic solvent gravure printing ink composition will be described.
When printing an organic solvent-based gravure printing ink composition, at an atmospheric temperature at the time of printing, an appropriate viscosity according to printing conditions, specifically, the outflow seconds of Zahn cup # 3 is 12 to 23 seconds. In order that the water content is 0.1 to 5% by mass, preferably 0.5 to 5% by mass, the dilution solvent (the dilution solvent at this time does not contain water even if it contains water). Dilute).
The diluted organic solvent-based gravure printing ink composition is a general gravure printing method in which the water content in the printing ink composition is 0.1 to 5% by mass, and the dilution solvent containing water is used. In addition, printing is performed on the printing substrate while maintaining. After printing, post-processing such as laminating and shrinking can be performed.

The printing substrate is not particularly limited, and is a polyolefin film such as polyethylene and polypropylene, a polyester film such as polyethylene terephthalate, polylactic acid, and polycaprolactone, various printing plastics such as nylon and vinylon, and may be a normal film. A heat shrinkable film may be used.
Moreover, as a printing plate to be used, a conventionally used plate cylinder (an intaglio plate made by a gravure plate making method, the plate making method being exemplified by engraving gravure) can be used. When the organic solvent-based gravure printing ink composition is an organic solvent-based gravure printing ink composition having a high pigment concentration, a cell having shallower cells than the conventional plate cylinder (shallowing) may be used. preferable.

The present invention maintains the storage stability of an organic solvent-based gravure printing ink composition until printing, and alleviates printing defects due to static electricity during printing, and prevents plate fogging and cell reproducibility. An economical gravure printing method that can be maintained economically is provided.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples. Unless otherwise specified, “%” means “% by mass”, and “part” means “part by mass”. Moreover, it is a "mass part" also about the number of the quantity of each material in Tables 1-5.

<Production example of polyurethane resin varnish A>
In a four-necked flask equipped with a stirrer, a condenser tube and a nitrogen gas inlet tube, 100 parts by mass of 3-methyl-1,5-pentanediol acrylate having an average molecular weight of 2000, 100 parts by mass of polypropylene glycol having an average molecular weight of 2000, and isophorone diisocyanate 44.4 parts by mass were charged and reacted at 100 to 105 ° C. for 6 hours while introducing nitrogen gas. After cooling to near room temperature, 518 parts by mass of ethyl acetate and 91 parts by mass of isopropyl alcohol were added, then 15.6 parts by mass of isophoronediamine was added to extend the chain, and 1.1 parts by mass of monoethanolamine was further added to react. The polyurethane resin varnish A (solid content 30% by mass) was obtained by stopping.

<Production example of polyurethane resin varnish B>
A four-necked flask equipped with a stirrer, a condenser tube and a nitrogen gas introduction tube was charged with 200 parts by mass of 3-methyl-1,5-pentanediol acrylate having an average molecular weight of 2000 and 44.4 parts by mass of isophorone diisocyanate, and nitrogen gas was added. Was allowed to react at 100 to 105 ° C. for 6 hours. After cooling to near room temperature, 518 parts by mass of ethyl acetate and 91 parts by mass of isopropyl alcohol were added, then 15.6 parts by mass of isophoronediamine was added to extend the chain, and 1.1 parts by mass of monoethanolamine was further added to react. The polyurethane resin varnish B (solid content 30% by mass) was obtained by stopping.

<Polyurethane resin solution>
To each 8.3 g of the polyurethane resin varnish A and B, 1.04 g of ethyl acetate and 0.63 g of isopropyl alcohol are added, and the polyurethane resin is dissolved in a mixed organic solvent having a mass ratio of ethyl acetate: isopropyl alcohol of 8: 2. To obtain polyurethane resin solutions A and B having a solid content concentration of 25% by mass.

(Isopropyl alcohol tolerance of organic solvent gravure resin solutions A and B)
Further, isopropyl alcohol was added to 10 g of each of the polyurethane resin solutions A and B, and the amount of isopropyl alcohol added until the polyurethane resin solutions A and B shifted from transparent to translucent was measured and evaluated (however, The liquid temperature is 25 ° C.).
A: The amount of isopropyl alcohol added is 25 g or less B: The amount of isopropyl alcohol added exceeds 25 g

(Isopropyl alcohol tolerance of organic solvent gravure resin solution C)
Acrylic resin (n-butyl methacrylate / 2-hydroxyethyl methacrylate / methyl methacrylate = 66/10/24, Mw = 60000, hydroxyl value = 40) in a mixed organic solvent consisting of 6.0 g of ethyl acetate and 1.5 g of isopropyl alcohol 1.85 parts by mass and 0.65 parts by mass of nitrocellulose (product name: LIG1 / 8, manufactured by SNP Japan) were dissolved to obtain a resin solution C. Furthermore, isopropyl alcohol was added, and the amount of isopropyl alcohol added until the resin solution C shifted from transparent to translucent was measured and evaluated (however, the liquid temperature was 25 ° C.).
A: The amount of isopropyl alcohol added is 25 g or less B: The amount of isopropyl alcohol added exceeds 25 g

(Measurement result)
The evaluation is A: polyurethane resin solution B
The evaluation is B: polyurethane resin solutions A and C

<Production Example of Ink Composition for Organic Solvent Gravure Printing>
35 parts by mass of pigment (titanium oxide) and 30 parts by mass of polyurethane resin varnish (24 parts by mass of polyurethane resin varnish A + 6 parts by mass of polyurethane resin varnish B) are mixed solvents (ethyl acetate / propyl acetate / isopropyl alcohol) shown in Table 1. = 50/25/25) A mixture with 10 parts by mass is kneaded using a paint conditioner, and the remaining solvent and water are added and mixed so as to have the composition shown in Table 1, and are not diluted with a diluting solvent. Ink compositions 1 and 2 for organic solvent gravure printing were prepared.

15 parts by mass of pigment (phthalocyanine blue pigment), 15 parts by mass of acrylic resin (n-butyl methacrylate / 2-hydroxyethyl methacrylate / methyl methacrylate = 66/10/24 Mw = 60000 hydroxyl value = 40), nitrocellulose (product) Name: LIG 1/8, manufactured by SNP Japan) 5.2 parts by mass, mixed solvent (ethyl acetate / propyl acetate / isopropyl alcohol = 26.1 / 46.4 / 27.5) according to the formulation in Table 1 An ink composition 3 for organic solvent-based gravure printing that was not diluted with a diluting solvent was prepared by kneading using a paint conditioner.

(Storage stability of organic solvent-based gravure printing ink compositions 1, 2 and 3)
Each of the organic solvent-based gravure printing ink compositions 1, 2 and 3 was collected in a glass bottle and evaluated for storage stability from the presence or absence of pigment settling when stored at an ambient temperature of 40 ° C. for 14 days. It was shown to.
A: No settling is observed, and the storage stability of the ink is good.
B: Ink sedimentation is observed, and ink storage stability is poor.

Gravure printing was performed by the methods of Examples 1 to 3 and Comparative Examples 1 to 3 using the gravure printing ink composition.
Dilution solvents used for gravure printing are as follows.
Diluent A: ethyl acetate / propyl acetate / isopropyl alcohol = 50/25/25
Diluting solvent B: ethyl acetate / propyl acetate / isopropyl alcohol / water = 47.5 / 23.75 / 23.75 / 5.0
Diluting solvent C: methylcyclohexane / isopropyl alcohol / ethyl acetate = 26.1 / 46.4 / 27.5
Diluting solvent D: methylcyclohexane / isopropyl alcohol / ethyl acetate / water = 24.8 / 44.1 / 26.1 / 5.0

Example 1
The organic solvent-based gravure printing ink composition 1 is diluted with 25 parts by weight of the dilution solvent B with respect to 100 parts by weight of the organic solvent-based gravure printing ink composition 1 during printing. After adjusting so that the viscosity measured with Zahn cup # 3 at 1% by mass and 25 ° C. is 15 seconds, engraving plate (Helio 200 line / inch, gravure printing plate having gradation of 10 to 100% halftone dot density) ), A treated surface of a polyethylene terephthalate film (Toyobo Co., Ltd., E-5101, thickness 12 μm, hereinafter referred to as a pet film) subjected to corona discharge treatment on one side by a gravure printing press (manufactured by Tohama Seisakusho) In addition, it is diluted so that the content of water in the ink composition for organic solvent gravure printing at the time of printing at 25 ° C./30% and a printing speed of 100 m / min is in the range of 0.5 to 1.5 mass%. B was subjected to 15 hours of continuous printing while adding.

(Example 2)
The organic solvent-based gravure printing ink composition 2 is diluted by adding 25 parts by weight of the dilution solvent B to 100 parts by weight of the organic solvent-based gravure printing ink composition 1 at the time of printing. After adjusting so that the viscosity measured by Zahn cup # 3 at 2.6 mass% and 25 degreeC may be set to 15 second, it is a gravure plate (Helio 200 line / inch, tone of 10-100% halftone dot density) Of a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., E-5101, thickness 12 μm, hereinafter referred to as a pet film) subjected to corona discharge treatment on one side by a gravure printing machine (manufactured by Tohama Seisakusho) equipped with a printing plate) The water content in the organic solvent-based gravure printing ink composition during printing at 25 ° C./30% and a printing speed of 100 m / min on the treated surface is in the range of 2.3 to 3.3 mass%. Nozomi The solvent B was 15 hours continuous printing while adding.

(Comparative Example 1)
The organic solvent-based gravure printing ink composition 1 is diluted by adding 25 parts by weight of the dilution solvent A to 100 parts by weight of the organic solvent-based gravure printing ink composition 1 at the time of printing. After adjusting the viscosity measured in # 3 to be 15 seconds, a gravure printing machine (Higashihama) equipped with an engraving plate (gravure printing plate having a helio 200 line / inch, halftone dot concentration of 10 to 100%) (Manufactured by Seisakusho Co., Ltd.), 25 ° C./30%, printed on the treated surface of a polyethylene terephthalate film (Toyobo Co., Ltd., E-5101, thickness 12 μm, hereinafter referred to as pet film) subjected to corona discharge treatment on one side. While adding dilution solvent A at a speed of 100 m / min, continuous printing was performed for 15 hours.

(Comparative Example 2)
The organic solvent-based gravure printing ink composition 2 is diluted with 25 parts by weight of the dilution solvent A with respect to 100 parts by weight of the organic solvent-based gravure printing ink composition 1 at the time of printing. After adjusting the viscosity measured in # 3 to be 15 seconds, a gravure printing machine (Higashihama) equipped with an engraving plate (gravure printing plate having a helio 200 line / inch, halftone dot concentration of 10 to 100%) (Manufactured by Seisakusho Co., Ltd.), 25 ° C./30%, printed on the treated surface of a polyethylene terephthalate film (Toyobo Co., Ltd., E-5101, thickness 12 μm, hereinafter referred to as pet film) subjected to corona discharge treatment on one side. While adding dilution solvent A at a speed of 100 m / min, continuous printing was performed for 15 hours.

(Example 3)
The organic solvent-based gravure printing ink composition 3 is diluted by adding 50 parts by weight of the dilution solvent D with respect to 100 parts by weight of the organic solvent-based gravure printing ink composition 1 during printing. After adjusting so that the viscosity measured by Zahn cup # 3 at 1.7 mass% and 25 degreeC may be set to 15 second, it is a gravure which has a gradation of a sculpture plate (Helio 175 line / inch, dot concentration of 10 to 100%) In a gravure printing machine (manufactured by Tohama Manufacturing Co., Ltd.) equipped with a printing plate) on a shrinkable PET film (product name: Space Clean S-7042, manufactured by Toyobo Co., Ltd.) at 25 ° C./30% and a printing speed of 100 m / min. Continuous printing was performed for 15 hours while adding the dilution solvent C so that the content of water in the ink composition 3 for organic solvent gravure printing at the time of printing was in the range of 1.2 to 2.2% by mass.

(Comparative Example 3)
The organic solvent-based gravure printing ink composition 3 is diluted with 50 parts by weight of the dilution solvent C with respect to 100 parts by weight of the organic solvent-based gravure printing ink composition 1 at the time of printing. After adjusting so that the viscosity measured in # 3 is 15 seconds, a gravure printing machine (Higashihama) equipped with an engraving plate (a gravure printing plate having a helio 175 line / inch, halftone dot concentration of 10 to 100%) (Manufactured by Seisakusho Co., Ltd.), continuous printing for 15 hours while adding dilution solvent C to shrinkable PET film (Product name: Space Clean S-7042, Toyobo Co., Ltd.) went.

(Evaluation)
<Electrostatic suitability>
The state of occurrence of static electricity suitability (whiskering, misting) of the printed film of the obtained printing part was visually confirmed and evaluated. The results are shown in Table 2.
A: Beard and misting do not occur.
B: Beard and misting occur due to static electricity failure.
<Cell reproducibility>
The print quality at the initial stage of printing was evaluated visually as a standard. The results are shown in Table 2.
A: The print quality is the same in all halftone dot density portions as compared with the standard.
B: Print quality is inferior to the standard at all halftone dot density portions.
<Plate fog prevention>
The state of occurrence of plate fog of the printing film of the obtained printing part was visually confirmed, and the plate fog prevention property was evaluated according to the following criteria. The results are shown in Table 2.
A: Plate fog does not occur.
B: Plate fogging occurs.

The printed films according to Examples 1 to 3 were excellent in all of electrostatic suitability, cell reproducibility, and plate fog prevention.
On the other hand, in the printing films according to Comparative Examples 1 to 3, the water content of the ink composition at the time of printing continued to decrease, and static electricity failure occurred.

According to the present invention, the storage stability of the organic solvent-based gravure printing ink composition up to the time of printing is kept good, and printing defects due to static electricity are mitigated at the time of printing, and plate fog is prevented and cell reproducibility is achieved. Can be continuously maintained, and an excellent gravure printing method can be provided.

Claims (3)

A gravure printing method using an organic solvent-based gravure ink composition containing a pigment, a binder resin, and an organic solvent,
The binder resin is less than 30% by mass of a polyurethane resin satisfying the isopropyl alcohol tolerance of the following condition 1.
A gravure printing method comprising printing while maintaining a water content in the organic solvent-based gravure printing ink composition in a range of 0.1 to 5% by mass.
<Condition 1> With respect to a polyurethane resin solution having a liquid temperature of 25 ° C. obtained by dissolving 2.5 g of a polyurethane resin in a mixed organic solvent composed of 6.0 g of ethyl isopropyl alcohol tolerance and 1.5 g of isopropyl alcohol, When isopropyl alcohol having a liquid temperature of 25 ° C. is added and the amount of isopropyl alcohol added until the polyurethane resin solution shifts from transparent to translucent is X (g), X satisfies 25 g or less. . Water content in the organic solvent-based gravure printing ink composition during printing by diluting the organic solvent-based gravure printing ink composition using a diluting solvent containing 0.2 to 10% by weight of water The gravure printing method according to claim 1, wherein the amount is maintained at 0.1 to 5 mass%. The dilution solvent is a mixed solvent of an ester organic solvent, an alcohol organic solvent, and water, and the mixing ratio of the ester organic solvent and the alcohol organic solvent is an ester organic solvent / alcohol organic solvent = The gravure printing method according to claim 2, which is in a range of 50/50 to 95/5.