JPH05171087A - Water-base flexographic ink composition - Google Patents

Abstract

PURPOSE:To obtain the title ink which in excellent in printability, does no suffer a decrease in laminate strength even after treatment with an aromatic solvent and excels in the durability of an ink film. CONSTITUTION:The title composition contains a water-soluble resin and a water-dispersible resin as the principal resin components, and the resin contains carboxyl and/or hydroxyl groups, 1-5wt.% metal chelate compound and 1-10wt.% epoxy compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to paper and plastics.
The present invention relates to a water-based flexo ink composition used for a film, which is a stable, easy-to-print ink in a one-component type when a laminated printing composition is prepared, and also reduces the adhesive strength when laminating and laminating a polyolefin film. And an aqueous flexo ink composition that provides an ink film having excellent resistance to an aromatic solvent used in post-processing, particularly toluene.

[Prior Art]

[0002] Conventionally, water-based flexo inks are mainly composed of a dispersion type resin as a main resin, and it is said that they are excellent in the physical properties of an ink coating film. However, their printability, especially clogging of anilox rolls and ink transfer on a plate. Fogging of plates due to poor quality is a problem. Toluene resistance is generally improved by using a resin with a high acid value, but aromatic monomers (mainly styrene or its derivatives) are used when synthesizing a resin with a high acid value due to the stability of the resin and the ease of manufacture. It is difficult to obtain toluene resistance in the aqueous flexo one-pack type ink based on this resin because of the copolymerization. On the other hand, in the case of a water-soluble resin, the acid value and molecular weight are adjusted for water-solubilization, but the acid value and molecular weight are limited due to dilution stability and printing viscosity. Therefore, the toluene resistance of the ink film obtained from the water-based flexo ink using the water-soluble resin is poor.
Furthermore, the adhesive strength under heat due to polyethylene extrusion processing or thermal compression bonding with pull-tap paper (bonding paper of polyethylene and paper) is based on the above-mentioned two types of water-soluble resin and water-dispersible resin. Difficult with liquid ink.

[Problems to be Solved by the Invention]

When laminating a water-based flexographic ink print with molten polyethylene, it has hitherto been difficult to obtain a stable laminate strength in the ink-printed portion. Further, in the one-pack type ink which maintains the printability, it is difficult to prevent the coating film from swelling due to the aromatic solvent used for the post-processing and the deterioration of the laminating strength. As a result of investigations by the present inventors, the metal chelate compound and the epoxy compound have a pH of 7
In the above areas, it was found that forming a cross-link bond by low temperature heat treatment maintains stable laminate strength and forms a coating film that is resistant to aromatic solvents used for post-processing. By applying it to ink, these problems have been solved.

[Means for Solving the Problems]

The present invention relates to a water-based flexo ink which has excellent printability, has no deterioration in laminate strength even after processing with a processing agent using an aromatic solvent, and has excellent ink film resistance. The water-soluble resin and water-dispersible resin mixed system is the main water-based ink resin, and the pH of the ink is
Is 7 or more, and 1 to 5% by weight of the metal chelate compound and 1 to 10% by weight of the epoxy compound are contained, which is an aqueous flexo ink composition.

A water-soluble resin is effective for printability, especially for preventing plate fogging and cell clogging of anilox roll.
However, since the water resistance is lowered, the combined use of the dispersion type resin becomes the most practical skeleton resin component.

A practical case will be described below. First, print on paper with water-based flexo ink, dry,
After the corona discharge treatment is performed by line processing, the printed surface and the PE are attached to each other by the extrusion laminating of polyethylene (PE). Thereafter, as a post-processing, a silicon-dissolved toluene solution is applied to the PE surface and dried, and then an adhesive toluene solution is applied onto the PE surface and wound up to finish the processing of the aqueous flexographically printed paper tape. At the time of use, the adhesive acts on the paper by the action of silicon to function as a paper tape. The post-processing refers to the step of applying a toluene solution of silicon to the surface after the PE bonding, drying and then applying the solvent-based adhesive again. A problem occurs when toluene used in these steps penetrates from the bonding interface with the polyethylene film or from the back surface of the paper and violates the coating film of the printing ink.

The water-soluble resin and the water-dispersible resin as main resin components are not limited as long as the resin contains a carboxyl group and / or a hydroxyl group.

The role of the metal chelate compound is to coordinate to the carboxyl group in the resin and to form a crosslink with the hydroxyl group by ring opening of the epoxy resin compound used in combination, so that the heat-curable resin is crystallized by melting at a high temperature. It compensates for the collapse of the resin and imparts toughness to the resin film.

The following compounds are used as the metal chelate compound. There are organic titanium compounds and organic aluminum compounds. Typical examples are tetraisopropyl titanate, dihydroxy-bis (lactate), titanium lactate ammonium salt, dipropoxytitanium-bis (ethyl acetate), tripropoxyaluminum, dipropoxyaluminum-ethylacetate and the like.
The range of the amount used is 1 to 5% by weight. When it is less than 1%, almost no effect is exhibited, and it is not useful for stabilizing the laminating strength during heating. When it exceeds 5% by weight,
Ink stability is impaired, which is not preferable.

The role of the combined epoxy resin is that the metal chelate compound alone hardly improves the resistance to toluene, and the combined use improves the resistance of the ink coating film for the first time, and the effect is easily evaluated by the rubbing test and the evaluation of cellophane tape. It is possible to evaluate it, and the reproducibility is obtained with this machine.

When pH> 7 in the ink, as an epoxy compound in which the reaction between the epoxy compound and the metal chelate compound easily proceeds by heat treatment (heat during extrusion or thermocompression bonding of PE-coated pull-tab paper) The following are used: Reaction product of glycidyl group having both ends with bisphenol skeleton and trimethylolpropane, reaction product of glycidyl group having both ends having bisphenol skeleton and glycerin, reaction product of lauryl alcohol ethylene oxide adduct and glycidyl group, sorbitol polyglycidyl ether, 1,6 hexanediol diglycidyl ether, phenyl glycidyl ether, bisphenol thiodiglycidyl ether, acryl glycidyl ether, and the like.

The amount used in combination is 1 to 10% by weight, preferably 2 to 5% by weight. When it is less than 1%, the combined effect is not recognized, and when it exceeds 10%, the stability of the ink is
It is not preferable because of changes in viscosity.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Production of Water-Dispersible Resin (a) 100 g of a styrene / acryl acrylate copolymer resin solution (oxidized 200, solid content 30% by weight, pH 8.2) is charged into a 500 ml four-necked flask. Then pH
Ammonia water (40 g) adjusted to 8.5 and ammonium persulfate (1 g) are stirred and dissolved to 70 ° C. When the temperature reached 70 ° C., 60 g of a mixture of 2 ethylhexyl acrylate / methyl methacrylate = 50/50 was stirred and 60
After dropwise addition for 3 minutes, 3 ml of ammonium persulfate (10% by weight aqueous solution) was added, and the reaction was terminated by keeping the temperature at 70 to 80 ° C. for 2 hours. The water-dispersible resin (a) obtained above was oxidized 67, solid content 30% by weight, pH 8.5,
The viscosity was 850 mPa.

Preparation of water-dispersible resin (b) Styrene / acrylic acrylate / β-hydroxyl methacrylate = 63 / in a 500 ml four-necked flask.
27/10 copolymer resin solution (oxidation 210, solid content 3
100 g of 0% by weight, pH 8.5 is charged. Then p
40 g of ammonia water adjusted to H8.5 and 1 g of ammonium persulfate are stirred and dissolved to 70 ° C. A mixture of styrene / methyl methacrylate / 2 ethylhexyl acrylate = 50/30/20 at 70 ° C. 120
g with stirring over 90 minutes, 10 ml of ammonium persulfate (10% by weight aqueous solution) was added, and 2 g was added.
The reaction was terminated by keeping the temperature at 70 to 80 ° C. The water-dispersible resin (b) obtained above had an oxidation of 42 and a solid content of 45.
It was 5% by weight, pH 8.5, and viscosity 300 mPa.

Preparation of water-dispersible resin (c) A copolymer resin solution of styrene / methyl methacrylate / acrylic acrylate / N-butoxymethyl acrylamide = 15/45/30/10 (oxidation 210 , Solid content 30% by weight, pH 8.
5) Charge 100 g. Then, 40 g of ammonia water adjusted to pH 8.5 and 1 g of ammonium persulfate are stirred,
Melt and heat to 70 ° C. 2 ethylhexyl acrylate / 2 ethyl hydroxy acrylate /
Mixture 6 of methyl methacrylate = 30/30/40
0 g was added dropwise with stirring over 90 minutes, and 3 ml of ammonium persulfate (10% by weight aqueous solution) was added, and 2 g was added.
The reaction was terminated by keeping the temperature at 70 to 80 ° C. The water-dispersible resin (c) obtained above had an oxidation of 70 and a solid content of 45.
It was 5% by weight, pH 8.5, and viscosity 300 mPa.

Example 1 Water-dispersible resin (a) 0.4 part Pigment (Carmine 6B) 16.0 parts Extender pigment (calcium carbonate) 5.0 parts Anionic activator 0.6 parts Water 24.9 parts The composition is made into a concentrated pigment aqueous solution with Red Tevir. Next, the following composition and the organometallic compound and epoxy compound shown in Table 1 were added to the obtained high-concentration dispersion aqueous solution to obtain an aqueous flexo ink. Water-soluble resin (styrene / acrylic acrylate copolymer resin solution 200, solid content 30% by weight, pH 8.2) 42.0 parts Water-dispersed wax 1.6 parts Defoamer 0.9 parts Isopropyl alcohol 4.0 The obtained aqueous flexo ink was applied to kraft paper with an applicator and dried at 60 ° C. for 5 minutes. A rubbing test and a dropping test were conducted as the toluene resistance of the coating film, and the results are shown in Table 2. Rubbing Test Method The absorbent cotton was made to contain toluene, and the printed matter was rubbed to determine the number of times when the absorbent cotton was colored. Dropping test Toluene was dropped onto the printed matter to evaluate the degree of dissolution of the ink coating film. 5: It did not dissolve at all. 4: 0 to 20% or less dissolved. 3: 20-50% or less melt | dissolved. 2: 50-70% or less melt | dissolved. 1: 70% or more dissolved.

Example 2 The water-dispersible resin (a) used in Example 1 was replaced with the water-dispersible resin (b), and the organometallic compounds and epoxy compounds shown in Table 1 were added. A water-based flexo ink was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 2.

Example 3 The water-dispersible resin (a) used in Example 1 was replaced with the water-dispersible resin (c), and the organometallic compounds and epoxy compounds shown in Table 1 were added. A water-based flexo ink was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 2.

Comparative Example 1 Water-dispersible resin (a) 0.4 part Pigment (Carmine 6B) 16.0 parts Extender pigment (calcium carbonate) 5.0 parts Anionic activator 0.6 parts Water 24.9 parts The composition is made into a concentrated pigment aqueous solution with Red Tevir. Next, the following composition and the organometallic compound and epoxy compound shown in Table 1 were added to the obtained high-concentration dispersion aqueous solution to obtain an aqueous flexo ink. A water-based flexo ink was prepared in the same manner as in Example 1 and evaluated in the same manner, and the results are shown in Table 2.

Comparative Example 2 The water-dispersible resin (a) used in Comparative Example 1 was replaced with the water-dispersible resin (c), and the organometallic compounds and epoxy compounds shown in Table 1 were added. A water-based flexo ink was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 2.

[0022]

INDUSTRIAL APPLICABILITY According to the present invention, it is a one-pack type ink which is stable and easy to print, especially when a laminated printing composition is prepared, and does not lower the adhesive strength when laminating a polyolefin film and is used in post-processing. It was possible to provide an ink film having excellent resistance to the aromatic solvent used, particularly toluene.

[Table 1]

[Table 2]

Claims (1)

[Claims] 1. A water-soluble resin and a water-dispersible resin are used as main resin components, the resin contains a carboxyl group and / or a hydroxyl group, a metal chelate compound is 1 to 5% by weight, and an epoxy compound is 1 to 10% by weight. A water-based flexo ink composition comprising: