JPH10152639A - Water-base printing ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-base printing ink which exhibits an excellent printability, printing effects, and laminating capability when used for printing a surface-treated plastic film by incorporating a water-base polyurethane resin and a specific aminated polyacrylamide into the same. SOLUTION: The aminated polyactylamide is pref. copolymer of acrylamide and acrylic acid hydrazide, pref. gas a content of hyrazide-derived units of 10-80mol%, and pref. has a wt. average mol.wt. of 1,000-2,500,000. The water- base polyurethane resin pref. has a number average mol.wt. of 1,000-20,000. The wt. ratio (solid basis) of the resin to the polyacrylamide is pref. (100:0.01)-(100:50).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous printing ink. More particularly, the present invention relates to an aqueous printing ink which is gravure or flexographically printed on a surface-treated plastic film, particularly a stretched polypropylene or polyester film, and has excellent laminating processability.

[0002]

2. Description of the Related Art In recent years, aqueous printing inks have been widely used for printing on general packaging paper and paper containers such as corrugated board.
However, in the field of printing on non-permeable plastic film substrates, mainly for soft packaging materials,
Except for some uses, aqueous printing inks have hardly been put to practical use. This is because in such a field, the quality of the aqueous printing ink is hardly sufficient compared to the solvent-based ink. In other words, the water-based printing ink has solved various problems such as uniform wettability and adhesion to a base material and applicability to lamination in addition to drying properties when a non-permeable plastic film is used as a printing medium. And it was extremely difficult to put it to practical use.

On the other hand, in the industry of printing on plastic films, in recent years, lots have been reduced and varieties have been diversified. To cope with this, work efficiency and economic efficiency have been improved by using so-called general-purpose inks that are adhered to various plastic films and can be applied to various uses. However, conventional water-based printing inks adhere to a surface-treated oriented polypropylene (OPP) film, and even if good lamination strength is obtained, the strength of the surface-treated polyester (PET) film is insufficient, However, there is a drawback that even if good strength is obtained with respect to the surface-treated PET film, sufficient strength cannot be obtained with respect to the surface-treated OPP film.

[0004] Furthermore, when an organic pigment is blended, it is possible to obtain an adhesive to a surface-treated OPP film or a surface-treated PET film, and to obtain a laminate strength in laminating a molten polyethylene by an extrusion laminating machine. When titanium (titanium) was added, there was a disadvantage that the lamination strength was insufficient. This is because the amount of titanium oxide in the aqueous printing ink is remarkably larger than that of the organic pigment, so that the amount of the resin which is an adhesion-imparting component is reduced.

[0005] In order to solve these drawbacks, attempts have been made to improve the coating film performance by adding a crosslinking agent having a functional group capable of reacting with the binder resin in the aqueous printing ink. For example, Japanese Unexamined Patent Publication No. 2-9937 discloses an aqueous solution containing one or more polymers selected from the group consisting of polyester resins, polyurethane resins and polyolefin resins and a compound having an oxazoline group. A resin composition is disclosed. However, those containing these reactive cross-linking agents have a problem in the stability of the ink due to the progress of the reaction over time.

Japanese Patent Application Laid-Open No. 61-19676 discloses an aqueous printing ink obtained by adding a tackifier resin such as rosin ester to a styrene / acrylic copolymer. From the performance of the coating,
It is difficult to obtain good adhesion to both the surface-treated OPP film and the surface-treated PET film.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aqueous printing ink which is excellent in printability, printing effect and lamination processability. More specifically, it is an object of the present invention to provide an aqueous printing ink which is gravure or flexographically printed on a surface-treated plastic film, particularly a stretched polypropylene film or a polyester film, and has excellent laminating processability.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, an aqueous printing ink using an aqueous polyurethane resin and an aminated polyacrylamide as a binder has a surface-treated polypropylene. The present invention was found to have good laminating strength in laminating, in which an adhesive coating agent was applied to a film and a polyester film, and a printing surface was coated with an anchor coating agent, and then a molten polyethylene was laminated by an extrusion laminating machine.

That is, the present invention relates to an aqueous printing ink containing an aqueous polyurethane resin and an aminated polyacrylamide. The present invention also relates to the above aqueous printing ink, wherein the aminated polyacrylamide is a copolymer of acrylic acid amide and acrylic acid hydrazide. The present invention also relates to the above aqueous printing ink, wherein the ratio of acrylic acid hydrazide in the aminated polyacrylamide is from 10 to 80 mol%.

The present invention also relates to an aminated polyacrylamide having a weight average molecular weight of 1,000 to 2,500,000
The aqueous printing ink according to the above, which is 0. The present invention also relates to the above aqueous printing ink, wherein the aqueous polyurethane resin has a number average molecular weight of 1,000 to 20,000. The present invention also relates to the above aqueous printing ink, wherein the weight ratio of the solid content of the aqueous polyurethane resin to the aminated polyacrylamide is from 100: 0.01 to 50.

[0011]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, an aqueous polyurethane resin is a polyurethane resin which is dissolved or dispersed in an aqueous medium, and a polyurethane resin having an ionic functional group such as a carboxyl group is preferably used. The aqueous medium is preferably water or a water-miscible organic solvent.
It is a mixture of water and a water-miscible organic solvent, which is contained in the range of up to 30% by weight. Examples of the water-miscible organic solvent include alcohol-based organic solvents such as ethyl alcohol, isopropyl alcohol, and normal propyl alcohol.

The aqueous polyurethane resin is prepared, for example, by reacting a polyol compound having an ionic functional group such as a carboxyl group, a polyisocyanate compound and, if necessary, another polyol compound under an isocyanate excess condition, to form a terminal of the polyol compound. Is obtained by preparing a prepolymer having an isocyanate group and then reacting a chain extender and, if necessary, a polymerization terminator. The number average molecular weight of the aqueous polyurethane resin is 1,000 to 2
000 is preferred. If the number average molecular weight is less than 1,000, sufficient coating film properties cannot be obtained. When the number average molecular weight exceeds 20,000, the viscosity of the aqueous solution or aqueous dispersion becomes high, and a sufficient printing effect cannot be obtained.

Examples of the polyol compound having a carboxyl group include 3,5-dihydroxybenzoic acid, 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid, and 2,2-bis ( Hydroxylethyl)
Propionic acid, 2,2-bis (hydroxypropyl) propionic acid, bis (hydroxymethyl) acetic acid, bis (4-hydroxyphenyl) acetic acid, 2,2-bis (4-hydroxyphenyl) pentanoic acid, tartaric acid, N , N-dihydroxyethylglycine, N, N-bis (2-hydroxyethyl) -3-carboxy-propionamide and the like.

The other polyol compound is not particularly restricted but includes, for example, water, ethylene glycol, diethylene glycol, triethylene glycol, butanediol, propanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol and the like. Low molecular weight glycols, trimethylolpropane, triols such as glycerin, low molecular weight polyols such as tetraols such as pentaerythritol, high molecular weight diols such as polyether diols and polyester diols, bisphenol A and bisphenol F Bisphenols are exemplified.

The polyether diols include, for example, tetrahydrofuran or alkylene oxide polymers such as ethylene oxide, propylene oxide and butylene oxide, block, random or graft copolymers, hexanediol, methylhexanediol, heptanediol, and the like. Examples include polyether glycols obtained by condensation of octanediol or a mixture thereof, and glycols obtained by adding an alkylene oxide such as ethylene oxide or propylene oxide to bisphenol A or bisphenol F.

As the polyester diols, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol,
Hexanediol, methyl-1,5-pentanediol, octanediol, cyclohexanediol, 2-ethyl-
Condensation reaction from a saturated or unsaturated low molecular weight glycol such as 1,3-hexanediol, bisphenol A, diethylene glycol, triethylene glycol, dipropylene glycol and an aliphatic or aromatic dibasic acid or an aromatic dibasic ester And polyester polyols obtained by ring-opening polymerization of cyclic ester compounds such as polyester polyols and ε-polycaprolactone, polycarbonate polyols, silicone polyols, and the like, and reaction products of terminal hydroxyl groups obtained by reacting these with diisocyanates. Can also be used.

As the polyisocyanate compound, one or a mixture of two or more aromatic, aliphatic and alicyclic conventionally known diisocyanates can be used. Specific examples of diisocyanates include tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate,
5-naphthylene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, lysine diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, dimer diisocyanate in which the carboxyl group of dimer acid is converted to an isocyanate group, or glycol and these Isocyanate adduct with both ends or diamines.

As the diisocyanates, tri- or more-functional polyisocyanates such as triphenylmethane triisocyanate and polymethylene polyphenyl isocyanate, and polyisocyanate adducts can be mixed and used as required. Further, if necessary, monoisocyanates can be used as a molecular weight modifier. Examples of commercially available polyisocyanate adducts include “Desmodur Series” manufactured by Bayer AG in West Germany.

The chain extender is a compound having two or more active hydrogens capable of reacting with an isocyanate group such as an amino group or a hydroxyl group, and examples thereof include a diamine compound, a dihydrazide compound, and glycols. Examples of the diamine compound include ethylenediamine, propylenediamine, hexamethylenediamine, triethyltetramine, diethylenetriamine, isophoronediamine, dicyclohexylmethane-4,4′-diamine, and polyoxyethylenediaminopropyl ether. Other examples include diamines having a hydroxyl group such as N-2-hydroxyethylethylenediamine and N-3-hydroxypropylethylenediamine, and dimerdiamines obtained by converting a carboxyl group of dimer acid into an amino group. Furthermore, diamine type amino acids such as glutamine, asparagine, lysine, diaminopropionic acid, ornithine, diaminobenzoic acid, diaminobenzenesulfonic acid and the like can be mentioned.

Examples of the dihydrazide compound include saturated aliphatic carboxylic acid dihydrazide having 2 to 18 carbon atoms, such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, and sebacic acid dihydrazide. Monohydric unsaturated dicarboxylic acid dihydrazide, such as acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide, phthalic acid dihydrazide, etc., carbonic acid dihydrazide, carbodihydrazide, thiocarbodihydrazide, and the like.

The glycols include ethylene glycol, diethylene glycol, triethylene glycol,
1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 1,6- Hexanediol, octanediol, 1,
Various known saturated or unsaturated low molecular weight diols such as 4-butylene diol and dipropylene glycol, and dimer diols obtained by converting a carboxyl group of a dimer acid into a hydroxyl group are exemplified.

Examples of the polymerization terminator include dialkylamines such as di-n-butylamine, monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, tri (hydroxymethyl) aminomethane and 2-amino- Amines having a hydroxyl group such as 2-ethyl-1,3-propanediol, N-di-2-hydroxyethylethylenediamine, N-di-2-hydroxyethylpropylenediamine, and N-di-2-hydroxypropylethylenediamine. Can be Further, monoamine-type amino acids such as glycine, alanine, glutamic acid, taurine, aspartic acid, aminobutyric acid, valine, aminocaproic acid, aminobenzoic acid, aminoisophthalic acid, and sulfamic acid are also included.

When producing an aqueous polyurethane resin,
In order to homogenize the reaction and adjust the viscosity, it is preferable to carry out the reaction in an organic solvent inert to isocyanate groups. Suitable organic solvents include acetone, methyl ethyl ketone, ethyl acetate, dioxane, acetonitrile, tetrahydrofuran, benzene, toluene, xylene, diglyme, dimethylsulfoxide, N-methylpyrrolidone, and the like, alone or in combination. Used. For the aqueous polyurethane resin, after the reaction is completed, a neutralizing agent for neutralizing the ionic functional group and water are added, and when the reaction is performed in an organic solvent, the organic solvent is azeotropically removed together with the water by a heating operation and a vacuum operation. In general, the aqueous printing ink is prepared from an aqueous solution or dispersion.

When the ionic functional group is a carboxyl group, a basic compound is used as a neutralizing agent. As the basic compound, ammonia; monoethylamine, diethylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, methyldiethanolamine, monoethanolamine, dimethylethanolamine, diethylethanolamine, morpholine, N-methylmorpholine, Organic amines such as 2-amino-2-ethyl-1-propanol; inorganic alkalis such as sodium hydroxide and potassium hydroxide; The basic compound is used alone or in combination of two or more. In order to improve the water resistance of the film after drying, a highly volatile compound that is water-soluble and easily dissociates by heat is used. Preferred, especially ammonia,
Trimethylamine and triethylamine are preferred.

The aminated polyacrylamide is a polymer represented by the following general formula: copolymerizing acrylic amide and acrylic hydrazide; reacting polyacrylamide with hydrazine; and copolymerizing acrylic amide and acrylic ester. It is produced by a method of reacting with hydrazine hydrate after polymerizing.

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The weight average molecular weight of the aminated polyacrylamide is 1,000 to 2,500,000,
It is preferably from 000 to 100,000. Also,
When acrylic acid amide and acrylic acid hydrazide are copolymerized, the ratio of acrylic acid hydrazide is preferably 10 to 80 mol%. The solid content weight ratio of the aqueous polyurethane resin to the aminated polyacrylamide is 10
0: 0.01 to 50, preferably 100: 0.1 to 10 When the proportion of the aminated polyacrylamide is less than the above range, the lamination strength becomes insufficient, and when the proportion is too large, the boil retort suitability and the pigment dispersibility decrease.

The water-based printing ink of the present invention may be used in an aqueous solution or dispersion of an aqueous polyurethane resin and an aminated polyacrylamide, as required, in order to impart necessary properties as an aqueous printing ink without impairing its function. Mixed with colorants such as pigments, extender pigments, other aqueous resins, waxes, defoamers, thickeners, curing agents, water and water-miscible organic solvents, etc. It is manufactured by performing dispersion using a machine and adjusting the viscosity to a predetermined value.

As the other aqueous resin, a resin soluble or dispersed in an aqueous medium, an intermediate hydrosol type resin, and a colloidal aqueous resin synthesized using a water-soluble resin as a protective colloid can be used. Specifically, it is synthesized from (meth) acrylic acid alkyl ester, other (meth) acryloyl group-containing monomer, styrene, α-methylstyrene, unsaturated carboxylic acid such as maleic acid, fumaric acid, or an ester thereof. (Meth) acrylic acid copolymer resin, carboxyl group-containing petroleum resin, cellulose resin, styrene maleic resin, shellac, aqueous polyester, or the like can be used alone or in combination.

The water-based printing ink of the present invention thus obtained is diluted with water or a mixture of water and a water-miscible organic solvent until it has an appropriate viscosity at the time of printing, and is then applied to a plastic film or the like by gravure printing or flexographic printing. Printed.

[0030]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” represents “parts by weight”, and “%” represents “% by weight”.

(Synthesis Example 1 of Aqueous Polyurethane Resin) While introducing nitrogen gas in a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube, poly (3-methyl-Mw = 2000) was used. 1,5-pentane adipate) diol 130.9
Parts, 15.2 parts of polyethylene glycol having Mw = 2000, 29.4 parts of 2,2-dimethylolpropionic acid, and 97.4 parts of isophorone diisocyanate were subjected to a boiling point reaction in 200 parts of methyl ethyl ketone for 6 hours to obtain a terminal isocyanate prepolymer, and then cooled to 40 ° C. Then, 100 parts of acetone was added to obtain an organic solvent solution of the terminal isocyanate prepolymer. Next, 26.6 parts of isophoronediamine and acetone
To the mixture obtained by mixing 400 parts, 572.9 parts of the obtained organic solvent solution of terminal isocyanate prepolymer was gradually added at room temperature, and reacted at 50 ° C. for 3 hours to obtain an organic solvent solution of a polyurethane resin having a carboxyl group. . Next, 13.3 parts of 28% ammonia water and 900 parts of deionized water were gradually added to an organic solvent solution of the above polyurethane resin to neutralize the mixture, and a mixed liquid containing a polyurethane resin having a carboxyl group and a basic compound was obtained. . The resulting mixture was desolvated at 60 ° C. under reduced pressure to obtain an aqueous dispersion (I) of an aqueous polyurethane resin having a number average molecular weight of 7,700. The resulting aqueous dispersion had a solids content of 25% and a pH of 6.8.

(Synthesis Example 2 of Aqueous Polyurethane Resin) A number average molecular weight of 6500 was obtained from the following raw materials in the same manner as in Synthesis Example 1.
To obtain an aqueous dispersion (II) of an aqueous polyurethane resin. The resulting aqueous dispersion had a solids content of 25% and a pH of 6.8. Poly (3-methyl-1,5-pentane adipate) diol (Mw = 2000) 130.9 parts Polyethylene glycol (Mw = 2000) 15.2 parts 2,2-Dimethylolpropionic acid 29.4 parts Isophorone diisocyanate 97.4 parts Methyl ethyl ketone 200 parts Acetone 100 parts Adipic dihydrazide 27.2 parts Acetone 400 parts 28% ammonia water 13.3 parts Deionized water 900 parts

(Synthesis Example 3 of Aqueous Polyurethane Resin) A number average molecular weight of 8500 was obtained from the following raw materials in the same manner as in Synthesis Example 1.
Thus, an aqueous dispersion (III) of an aqueous polyurethane resin was obtained. The resulting aqueous dispersion had a solid content of 25% and a pH of 6.8. Polytetramethylene ether glycol (Mw = 3000) 159.8 parts Polypropylene ether glycol (Mw = 2000) 15.0 parts 2,2-dimethylolpropionic acid 21.5 parts Isophorone diisocyanate 78.8 parts Methyl ethyl ketone 200 parts Acetone 100 parts Isophorone diamine 23.2 parts Dibutylamine 1.7 parts Acetone 400 parts 28% ammonia water 9.7 parts Deionized water 900 parts

Example 1 A water-based printing ink was prepared according to a conventional method with the following composition. Aqueous dispersion of aqueous polyurethane resin (I) 69 parts Copolymer of acrylic acid amide and acrylic acid hydrazide 1 part (weight average molecular weight 5000, ratio of acrylic acid hydrazide 50 mol%) Phthalocyanine blue pigment 18 parts (Toyo Ink Manufacturing) (Lionol Blue KLH, manufactured by K.K.) Water 6.9 parts Isopropyl alcohol 5 parts Silicone defoamer 0.1 part (Toray Silicone SC5540, Toray Silicone Co., Ltd.)

Example 2 An aqueous dispersion of an aqueous polyurethane resin (I) was used in an amount of 69 parts.
I) Example 1 except that the copolymer of acrylic acid amide and acrylic acid hydrazide was changed from 1 part to 10 parts instead of 60 parts.
A water-based printing ink was prepared in the same manner as described above.

Example 3 Aqueous dispersion of aqueous polyurethane resin (I) 69 parts of aqueous dispersion of aqueous polyurethane resin (I)
II) In place of 65 parts, 1 part of a copolymer of acrylamide and acrylic acid hydrazide was replaced with 5 parts of a copolymer of acrylic acid amide and acrylic acid hydrazide having a weight average molecular weight of 250,000 and a ratio of acrylic acid hydrazide of 50 mol%. A water-based printing ink was prepared in the same manner as in Example 1 except for the above.

Comparative Example 1 An aqueous printing ink was prepared in the same manner as in Example 1 except that the copolymer of acrylic acid amide and acrylic acid hydrazide was omitted.

The aqueous printing inks obtained in Examples and Comparative Examples were mixed with water / isopropyl alcohol = 1/1 (weight ratio) in Zahn Cup # 3 (manufactured by Rigosha Co., Ltd.) so as to reach 18 seconds (25 ° C.). Dilute with a mixed solvent and use corona-treated polyester (PE
T) Film (“Ester E5100” manufactured by Toyobo Co., Ltd.
Corona-treated polypropylene (OPP) film (Pyren P2161 manufactured by Toyobo Co., Ltd., thickness 20μm)
m), a corona-treated nylon (NY) film (“Emblem ON” manufactured by Unitika Ltd., thickness 15 μm), a drying temperature of 60 ° C. and a printing speed of 80 m using a gravure plate having a plate depth of 25 μm. / Min gravure printing, adhesive,
Extrusion lamination strength and boil retort suitability were evaluated by the following methods. Table 1 shows the results.

(1) Adhesion After the printed matter was left for one day, a cellophane tape was stuck on the printing surface, and the state of the printed film when the cellophane tape was rapidly peeled off was visually observed. The evaluation criteria are as follows. 5: The printed film was not peeled at all. 4: 80% or more of the printed film remained on the film. 3: 50-80% of the printed film remained on the film. 2: 30-50% of the print film remained on the film. 1: Less than 30% of the print film remained on the film.

(2) Extrusion laminating strength A polyethyleneimine-based anchor coating agent was applied to the plastic film printed matter, and the extruded laminating machine was used to laminate the molten polyethylene. On the second day after lamination, the sample was cut into a 15 mm width. The peel strength was measured.

(3) Boil retort suitability A urethane-based adhesive is applied to the printed nylon film,
After laminating an unstretched polypropylene film with a dry laminating machine and aging at 40 ° C. for 3 days, a laminate is formed into a bag, and as a content, a mixture of water / salad oil / ketchup = 1/1/1 is put and sealed. 100 ° C for 30 minutes for boiling suitability, 120 for retort suitability
After heating at 30 ° C. for 30 minutes, the presence or absence of lamination was visually determined. When no lamination occurred, the sample was evaluated as 全面, and when the entire surface was identified, ×.

[0042]

[Table 1]

[0043]

According to the present invention, it is possible to provide an aqueous printing ink which is gravure-printed or flexographic-printed on a surface-treated plastic film and has excellent suitability for laminating.

Claims (6)

[Claims] 1. An aqueous printing ink comprising an aqueous polyurethane resin and an aminated polyacrylamide. 2. The aqueous printing ink according to claim 1, wherein the aminated polyacrylamide is a copolymer of acrylic acid amide and acrylic acid hydrazide. 3. The aqueous printing ink according to claim 2, wherein the ratio of acrylic acid hydrazide in the aminated polyacrylamide is 10 to 80 mol%. 4. The aqueous printing ink according to claim 1, wherein the weight average molecular weight of the aminated polyacrylamide is 1,000 to 2,500,000. 5. The aqueous printing ink according to claim 1, wherein the aqueous polyurethane resin has a number average molecular weight of 1,000 to 20,000. 6. The weight ratio of the solid content of the aqueous polyurethane resin to the aminated polyacrylamide is from 100: 0.01 to 50.
The aqueous printing ink according to any one of claims 1 to 5, wherein