JPH05271599A - Aqueous printing ink composition for laminate - Google Patents

Abstract

PURPOSE:To obtain an aqueous printing ink composition for laminate having good printability, excellent adhesion to various kinds of plastic films and a higher laminate strength. CONSTITUTION:In the objective aqueous printing ink composition for laminate mainly composed of a pigment, an aqueous binder resin and water, the binder resin consists of (A) 95-50wt.% water dispersible, self-emulsifiable and water-soluble polyurethane resin having 20-100 acid value and (B) 5-50wt.% water dispersible ethylene-acrylic acid copolymer having 100-2000g/10min melt index and consisting of (1) 60-90wt.% ethylene, (2) 10-30wt.% acrylic acid and (3) 0-30wt.% other vinyl group-containing compound copolymerizable with ethylene and acrylic acid based on weight of the polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous printing ink for laminating printed on various plastic films,
The present invention provides a water-based printing ink composition for laminating, which has more excellent printability, adhesiveness and laminating strength.

[0002]

2. Description of the Related Art In recent years, with the diversification of packaging containers, coating agents used for decoration and surface protection, and in particular, various coating agents applied to the film surface, are not sufficiently adhered to the adherend. Adhesiveness, various types of resistance, and suitability for post-processing are required.

For example, printing inks for plastic films are required to have not only excellent printability, adhesiveness to various films, and various resistances, but also suitability for lamination according to the intended use of these printed matters. ..

Therefore, in the past, as a printing ink for laminating intended for a plastic film, an organic solvent type ink using a polyurethane resin, a polyester resin, an acrylic resin, a polyamide resin or the like as a binder resin is used depending on the required performance. Has been used. Above all,
Polyurethane resins having excellent adhesiveness to a wide range of plastic films have been widely used as binder resins. However, recently, from the standpoints of environmental problems, resource saving, labor safety, fire, etc., there has been a strong demand for water-based printing inks that minimize the use of organic solvents.

In printing on paper, many printing inks have been transferred to the water-based type from early on, but in printing on plastic films and the like, an acrylic resin, which is relatively easy to be water-based, is used as a binder. Although some of these water-based inks have been put to practical use, applicable films are limited to polyolefins, and their laminating suitability is not sufficient.

Therefore, it has been studied to make a polyurethane resin aqueous, which has excellent adhesiveness to a wide range of films. Generally, an aqueous polyurethane resin is prepared by reacting an organic diisocyanate compound with a polyester or polyether type polymer diol to synthesize a urethane prepolymer, chain-extending with a chain extender, dispersing in water, self-emulsifying or dissolving. Is what you get. For such a type of aqueous polyurethane resin, in order to make the solubility and dispersibility more stable in an aqueous system, an aliphatic polyether or aliphatic polyester-based material having as high hydrophilicity as the diol component is used. Was necessary.

However, the aqueous polyurethane resin made of these highly hydrophilic materials has high crystallinity and has few functional groups contributing to adhesion with the plastic film. Not only was the adhesion to a film such as PET (polyethylene terephthalate) poor, but also the adhesion to the molten polymer used in the laminating process was poor. In addition, since the wetness with the anchor coating agent or the adhesive applied during the laminating process becomes poor, there is a problem that good laminating suitability cannot be obtained.

Therefore, the applicant of the present application has proposed a system using a polymer diol containing an aromatic dicarboxylic acid and a glycol having a side chain as a diol component of a self-emulsifying and water-soluble polyurethane resin, a polymer containing a polycarbonate diol. It was found that a water-based ink using a system using a diol as a binder resin has good adhesiveness to a PET film or the like and improves the laminate strength. Japanese Patent Application No. 2-305452 and Japanese Patent Application No. 3-305452. 354
Proposed as No. 568.

Aqueous inks containing these self-emulsifying and water-soluble polyurethane resins as binder resins show excellent improving effects in terms of adhesion to a wide range of films and laminating strength, as compared with conventional aqueous inks. Compared to solvent-based inks, the laminate strength is still low, and it is not sufficient for application under severe conditions that require stronger laminate strength.

Further, since the self-emulsifying and water-soluble polyurethane resin has a lower re-solubility as compared with a solvent-based one, plate clogging is likely to occur, and printability such as fine character reproducibility and gradation reproducibility is improved. In terms of aspects, it was not enough.

[0011]

Therefore, the present invention is intended to solve the above problems of a water-based printing ink composition for laminating using a water-dispersible, self-emulsifying and water-soluble polyurethane resin as a binder resin. It is an object of the present invention to provide a water-based printing ink composition for lamination, which has better printability, excellent adhesion to a wide range of plastic films, and higher laminate strength.

[0012]

That is, the present invention relates to a water-based printing ink composition for lamination mainly composed of a pigment; a water-dispersible, self-emulsifying and water-soluble binder resin; 95 to 50% by weight of water-dispersible, self-emulsifying and water-soluble polyurethane resin having an acid value of 20 to 100, B. 60 to 90% by weight, based on the weight of the copolymer
Ethylene, 10 to 30% by weight acrylic acid,
Water-dispersible ethylene-acrylic acid type copolymer having a melt index of 100 to 2000 g / 10 min, which comprises 0 to 30% by weight of ethylene and other vinyl group-containing compound copolymerizable with acrylic acid, and 5 to 50% by weight. The present invention relates to a water-based printing ink composition for lamination, which comprises:

The aqueous printing ink composition for lamination according to the present invention will be described in more detail below. As the water-dispersible, self-emulsifying and water-soluble polyurethane resin having an acid value of 20 to 100 according to the present invention, first, a urethane prepolymer composed of an organic diisocyanate compound and a high molecular weight diol compound is synthesized, and a chain extender is used to extend the chain. Water-dispersible, self-emulsifying and water-soluble polyurethane resins can be used.

Here, as the organic diisocyanate compound, aliphatic diisocyanate compounds such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate,
Hydrogenated xylylene diisocyanate, alicyclic diisocyanate compound such as 4,4-cyclohexylmethane diisocyanate, xylylene diisocyanate, aromatic aliphatic diisocyanate compound such as tetramethyl xylylene diisocyanate, toluene diisocyanate, aromatic diisocyanate compound such as diphenylmethane diisocyanate Can be mentioned. Among them, the araliphatic diisocyanate compound is preferable from the viewpoint of improving the adhesiveness to various films and the resolubility of the water-based printing ink.

Further, as the high molecular diol compound, 1,3-propanediol, 1,3-propanediol as the aliphatic diol,
Linear glycols such as 4-butanediol and 1,6-hexanediol, branched glycols such as 1,2-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol and ethylbutylpropanediol. Is mentioned.

Further, ether diols such as diethylene glycol and triethylene glycol, polyether diols which are polymers or copolymers such as ethylene oxide, propylene oxide and tetrahydrofuran, and saturated and unsaturated low molecular weight glycols. Polyester diols obtained by dehydration condensation reaction with dibasic acid or obtained by ring opening reaction of cyclic ester compound such as lactone, alkylene carbonate, diallyl carbonate, carbonate component such as dialkyl carbonate or phosgene, 1, Examples thereof include polycarbonate diols and polybutadiene glycols obtained by reacting with a diol component such as 3-propanediol, 1,4-butanediol, and 1,6-hexanediol. Among them, polycarbonate diols are preferable from the viewpoint of improving the adhesiveness to various films.

Next, as chain extenders, glycols such as ethylene glycol and propylene glycol, and aliphatic diamines such as hydrazine, ethylenediamine, 1,4-butanediamine, and aminoethylethanolamine are used alone and glycerin, 1 Used in combination with aliphatic polyols such as 1,2,3-trimethylolpropane and pentaerythritol, alicyclic polyols such as 1,3,5-cyclohexanetriol, and aliphatic polyamines such as diethylenetriamine and triethylenetetramine You can also do it.

Regarding the production of a water-dispersible polyurethane resin comprising the above components, a urethane prepolymer is synthesized by reacting the organic diisocyanate compound and a polymer diol compound, and the urethane prepolymer is used in water with an emulsifier. After dispersion, the chain is extended with a chain extender, or the urethane prepolymer is dissolved in a water-miscible solvent such as acetone, and the chain is extended with a chain extender,
It can be produced by mixing with water containing an emulsifier and removing the solvent by evaporation.

Further, in order to obtain a self-emulsifying and water-soluble polyurethane resin, a compound represented by the general formula (1) together with the above chain extender,

[Chemical 1] (R in this formula represents a hydrogen atom or a linear or side chain alkyl group having 1 to 8 carbon atoms), or succinic acid, adipic acid, phthalic acid, pyromellitic acid, trimellitic acid and its Carboxylic acid-containing polyols obtained by reacting a polycarboxylic acid such as an anhydride with a lower polyol can be used in combination as a chain extender, and a free carboxyl group can be introduced into the molecule to make it aqueous. Further, a monoalcohol containing a carboxyl group can be used as a reaction terminator.

The content of free carboxyl groups required for the self-emulsifying and water-soluble polyurethane resin must be such that the acid value of the polyurethane resin is 20 to 100. If the acid value is lower than 20, it will be difficult for the resulting polyurethane resin to maintain a stable emulsified or dissolved state in an aqueous system, while if the acid value exceeds 100,
The resin film obtained becomes hard and good physical properties cannot be obtained.

Further, as an alkaline compound for neutralizing a free carboxyl group for self-emulsification and water-solubilization, aqueous ammonia, diethylamine as an organic amine,
Alkylamines such as triethylamine, ethylenediamine, monoethanolamine, ethylethanolamine,
Examples of alkanolamines such as diethylethanolamine and alkali metal hydroxides include sodium hydroxide and potassium hydroxide.

Among them, those which easily dissociate and volatilize at room temperature or with slight heating are desirable in order to improve the drying property.

Regarding the production of the self-emulsifying and water-soluble polyurethane resin comprising the above components, a urethane prepolymer comprising the above organic diisocyanate compound and a high molecular weight diol compound is synthesized and the chain is extended with a chain extender having a free carboxyl group. It can be produced by extending and introducing a free carboxyl group into the polyurethane molecule, and neutralizing this with an alkali compound in water.

The molecular weight of the polyurethane resin obtained by such a method is 10,000 to 200,000, preferably 2
It is 0000 to 100,000. When the molecular weight is less than 10,000, the resin film has poor elasticity and becomes brittle.
When the molecular weight exceeds 200,000, the viscosity of the water-soluble polyurethane resin solution becomes high, and it becomes difficult to make the water-dispersible polyurethane resin aqueous.

Next, the water-dispersible ethylene-acrylic acid copolymer according to the present invention comprises 60 to 90% by weight of ethylene, 10 to 30% by weight of acrylic acid or methacrylic acid, and ethylene, based on the weight of the copolymer. Other vinyl group-containing compound copolymerizable with acrylic acid 0 to 30% by weight
Is a copolymer obtained by copolymerizing

Here, other vinyl group-containing compounds copolymerizable with ethylene and acrylic acid include alkyl esters of acrylic acid or methacrylic acid, acrylamides, styrenes such as styrene and vinyltoluene, vinyl chloride, vinyl. Acetate or the like can be used.

The ethylene-acrylic acid type copolymer is obtained by directly copolymerizing a predetermined amount of ethylene, acrylic acid and other copolymerizable vinyl group-containing compound under a high temperature and a high pressure using a catalyst, or ethylene. -It is obtained by hydrolyzing an alkyl acrylate-based copolymer. For example, as pelletized solid resin, ethylene-acrylic acid copolymer A-200W and the like are commercially available from Mitsubishi Petrochemical Co., Ltd.

These copolymer resins are used as an aqueous resin varnish by adding an alkali compound. For example, as a water-dispersed liquid resin varnish, Saixen A is commercially available from Sumitomo Seika.

Here, the content of acrylic acid is 10% by weight.
When the amount is less, the emulsifying ability of the copolymer with respect to water becomes low, and precipitation / precipitation becomes unusable. On the other hand, when the content of acrylic acid exceeds 30% by weight, the drying property decreases.

When the content of the other copolymerizable vinyl group-containing compound exceeds 30% by weight, the ink performance specified in the present invention cannot be obtained.

The ethylene-acrylic acid copolymer according to the present invention has a melt index of 100 to 2000 g / 10.
Min, more preferably 300 to 1000 g / 10 min. The melt index of the copolymer is 100
If it is less than g / 10 minutes, the dispersion stability of the resin in water will be low, and it will become unusable due to precipitation / precipitation. If it exceeds 2000 g / 10 minutes, the resin will become too soft and the resulting water-based ink will be obtained. Blocking occurs between the printed surface and the film.

As the alkali compound for water-dispersing the ethylene-acrylic acid type copolymer, the same aqueous ammonia, organic amine and alkali metal hydroxide as described above can be used, and the free carboxyl of the copolymer is used. It may be reacted with the base. The amount of the alkaline compound added varies depending on the amount of the free carboxyl groups of the copolymer, but it is usually about 0.5 to 1.5 equivalents. When the amount of the alkali compound added is small, the water dispersibility of the ethylene-acrylic acid copolymer decreases, and when it is large, the drying property decreases.

Aqueous printing for lamination using a water-dispersible, self-emulsifying and water-soluble polyurethane resin having an acid value of 20 to 100 and a water-dispersible ethylene-acrylic acid copolymer synthesized from the above components. In the case of producing an ink composition, the water-dispersible aqueous polyurethane resin, a self-emulsion or an aqueous solution as a grind varnish, or a mixture with a water-dispersible ethylene-acrylic acid copolymer as a grind varnish, a colorant. Various pigments,
If necessary, a pigment dispersant is mixed and kneaded, and then a predetermined amount of water-dispersible, self-emulsifying and water-soluble polyurethane resin having an acid value of 20 to 100 and a water-dispersible ethylene-acrylic acid copolymer are added. It can be added and manufactured.

If desired, various other aqueous (water-dispersible, self-emulsifying and water-soluble) resins such as cellulose,
Maleic acid resin, acrylic resin, antiblocking agent as an additive, antifoaming agent, cross-linking agent such as aziridine type, hydrazine type, epoxy compound, blocked isocyanate compound, metal chelate compound, further methanol as a solvent mixed with water, By adding ethanol, isopropanol, methoxypropanol, N-methylpyrrolidone, etc., an aqueous printing ink composition for lamination can be produced.

The aqueous printing ink for lamination obtained according to the present invention can be printed on plastic films such as low density polyethylene, unstretched and stretched polypropylene, cellophane, polyester, nylon and various K-coated films by a gravure or flexographic printing method. It is possible.

Further, as a method for obtaining a laminated product by using the water-based printing ink specified in the present invention, after printing the ink on the plastic film, an anchor coating agent or an adhesive agent is applied to melt or form a film. The polymer can be laminated by a conventional method to obtain a laminated product.

The aqueous printing ink composition for laminating obtained in the present invention solves the problems of the aqueous printing ink for laminating obtained from the conventional aqueous (water dispersible, self-emulsifying and water-soluble) polyurethane resin, It has excellent adhesiveness to various plastic films, printability, and good post-processability such as good laminating.

[0038]

EXAMPLES The present invention will be described more specifically according to examples, but the invention is not limited thereto. The term "parts" in the examples means parts by weight. [Synthesis of Aqueous Polyurethane Resin Varnish] Synthesis Example 1 In a four-necked flask equipped with a thermometer, a stirrer, and an N ₂ inlet tube, 300 parts of a polycarbonate diol having an average molecular weight of 2000 and isophorone diisocyanate 66.6.
Part, and while introducing N ₂ gas, 100 to 105
The reaction is carried out at 4 ° C for 4 hours, then 22.1 parts of dimethylolpropionic acid are charged, and the reaction is carried out at 100 to 110 ° C until the NCO group disappears.

After the reaction is completed, the reaction mixture is cooled to 100 ° C. and water 90
8 parts and 16.7 parts of trimethylamine are added to make it aqueous. The resin solution A thus obtained has a solid content of 30% and a viscosity of 2.2.
It was a polyurethane resin solution having a poise / 25 ° C. and an acid value of 23.8.

Synthesis Example 2 Poly-3 having an average molecular weight of 1000 was placed in the same apparatus as in Synthesis Example 1.
150 parts of methylpentylene adipate, 150 parts of polyester diol consisting of isophthalic acid / adipic acid (molar ratio 50/50) and 3-methyl-1,5-pentanediol, and isophorone diisocyanate 14
While charging 6.5 parts and introducing N ₂ gas, 90 to 9
After reacting at 5 ° C. for 4 hours, after the reaction, 118 parts of 1-methyl-2-pyrrolidone, 46.3 parts of dimethylpropionic acid, and 11.6 parts of trimethylolpropane were added, and 140 to 15
The reaction is carried out at 0 ° C. until the NCO group disappears. After completion of the reaction, the mixture is cooled to 100 ° C., and 1059 parts of water and 34.9 parts of triethylamine are added to solubilize it. The obtained resin solution B was a polyurethane resin solution having a solid content of 30%, a viscosity of 4.5 poise / 25 ° C. and an acid value of 38.

Synthesis Example 3 300 parts of polypentylene adipate having an average molecular weight of 1000 and 146.5 parts of isophorone diisocyanate were charged in the same apparatus as in Synthesis Example 1, and N ₂ gas was introduced at 90 to 95 ° C. for 4 hours. After the reaction, after the reaction, 118 parts of 1-methyl-2-pyrrolidone, 11.6 parts of trimethylolpropane and 46.3 parts of dimethylolpropionic acid were charged and reacted at 140 to 150 ° C. until the NCO group disappeared. After the reaction is completed, the reaction mixture is cooled to 100 ° C. and water 1059
Parts and 34.9 parts of trimethylamine are added to make the mixture aqueous. The resin solution C thus obtained has a solid content of 30% and a viscosity of 4.1.
It was a polyurethane resin solution having a poise / 25 ° C. and an acid value of 38.

Synthetic Example 4 150 parts of isopropanol, 350 parts of ethyl acetate and 4 parts of benzoyl peroxide were added to the same apparatus as in Synthetic Example 1, and 7 parts were added.
The temperature is raised to 5 to 78 ° C. Then styrene 72.5
Part, 70 parts of methyl methacrylate, 90 parts of 2-ethylhexyl methacrylate, and 17.5 parts of acrylic acid are added dropwise over about 2 hours, and the mixture is further reacted for 3 hours. To the crushed product of the resin obtained by evaporating the solvent, 264 parts of ethanol, 528 parts of water, and 14 parts of dimethylamino alcohol were added, and dissolved by stirring at 70 ° C. to obtain a solid content of 25% and a viscosity of 2.4 poise / 25. A water-soluble acrylic resin solution A having an acid value of 60 and an ethanol value of 25% was obtained.

[Production of Aqueous Printing Ink Composition] Examples 1 to 5 and Comparative Examples 1 and 2 were prepared by mixing and kneading the inks according to the compositions shown in Tables 1 and 2. As a pigment, Fast Gemble-5412
SD (Dainippon Ink and Chemicals Incorporated), polyurethane resin as the resin solution A, ethylene-acrylic acid copolymer as a water-dispersible ethylene-acrylic acid copolymer A (Saixen AC, Sumitomo Seika, content of acrylic acid) 20% by weight,
A melt index of 300 g / 10 min, ammonia neutralization, and solid content of 30% by weight) were used.

Examples 6 and 7 and Comparative Examples 3 and 4 Each ink was prepared by mixing and kneading the compositions shown in Tables 1 and 2. As the polyurethane resin, the same resin solution B and other materials as in Examples 1 to 5 were used.

Example 8 and Comparative Examples 5 and 6 Each ink was prepared by mixing and kneading the compositions shown in Tables 1 and 2. As the polyurethane resin, the resin solution C and other materials used were the same as those in Examples 1 to 5.

Comparative Example 7 The composition shown in Table 2 was mixed and kneaded to produce. As the ethylene-acrylic acid copolymer, water-dispersible ethylene-
Acrylic acid copolymer B (acrylic acid content 20% by weight, melt index 2300 g / 10 minutes, ammonia neutralization, solid content 30% by weight), other materials are those of Example 1
The same as ~ 5 was used.

Comparative Example 8 The composition shown in Table 2 was mixed and kneaded to produce. As a pigment, Fast Gemble-5412SD (Dainippon Ink and Chemicals) was used, and as an aqueous acrylic resin, a resin solution D was used.

[Evaluation Test] After printing on OPP (stretched polypropylene) and PET film using each printing ink, the adhesiveness, re-dissolving property, blocking resistance and laminating suitability were evaluated and the results are shown in a table. 3 and Table 4. In addition, each evaluation method was performed by the following methods.

1) Adhesion test method Each ink was used for printing OPP and PET films with a gravure proofing machine, left for 1 day, and then a cellophane tape was attached to the printed surface, which was rapidly peeled off. Evaluation method A: The printed film was not peeled at all B: 80% or more remained on the film C: 50 to 80% remained D: Only 20% or less remained

Re-solubility Test Method After running the test ink for 10 seconds using a gravure proofing machine, stop the operation and leave it for 60 seconds. Subsequently, printing is performed on the OPP film, and the re-solubility of the ink is judged from the number of pitches until a normal printed matter is obtained. Evaluation method A: Return to normal within 5 pitches B: Return to normal within 6 to 20 pitches C: Return to normal with pitches 21 to 40 D: Not return to normal with 40 pitches

Blocking resistance test method The printed surface and the back surface of the film are put together in a vise, left at an ambient temperature of 40 ° C. under an environmental condition of 90% humidity for 24 hours, and then peeled by hand to obtain peeling resistance and printing. Blocking resistance is judged based on how ink is taken from the surface. Evaluation method A: There is no resistance and the film peels from the printed surface. B: There is resistance when the film is peeled from the printed surface,
No ink is taken from the printed surface C: There is resistance when peeling the film from the printed surface, and 1 to 20% of ink is taken from the printed surface D: There is resistance when peeled from the printed surface , 21% or more of ink is taken from the printing surface

Extrusion Lamination Suitability Testing Method Polyimine type anchor coating agent (Oribain EL-
No. 420, Toyo Morton) was applied, molten polyethylene was laminated by an extrusion laminating machine, and heated at 40 ° C. for 3 days. Evaluation method The sample was cut into a width of 30 mm, and the T-type peel strength (gram) was measured with a peel tester manufactured by Yasuda Seiki.

Test Method for Suitability for Dry Lamination A PET film printed matter is printed with an isocyanate type adhesive (adcote AD-300 A / D).
Toyo Morton) was applied, a CPP (cast polypropylene) film was laminated, and heated at 40 ° C. for 3 days. Evaluation method The sample was cut into a width of 30 mm, and the T-type peel strength (gram) was measured with a peel tester manufactured by Yasuda Seiki.

[0054]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[0055]

[Effects] As described above, as shown in the examples, the water dispersibility according to the present invention, the self-emulsifying property having an acid value of 20 to 100, and the water-soluble polyurethane resin and the water-dispersible ethylene-acrylic acid copolymer are used. It can be seen that the printing ink has a wide range of adhesion to various films and has excellent printability and laminate strength.

Claims (3)

[Claims] 1. A water-based printing ink composition for lamination mainly comprising a pigment; a water-dispersible, self-emulsifying and water-soluble binder resin; 95 to 50% by weight of water-dispersible, self-emulsifying and water-soluble polyurethane resin having an acid value of 20 to 100, B. 60 to 90% by weight, based on the weight of the copolymer
Ethylene, 10 to 30% by weight acrylic acid,
Water-dispersible ethylene-acrylic acid type copolymer having a melt index of 100 to 2000 g / 10 min, which comprises 0 to 30% by weight of ethylene and other vinyl group-containing compound copolymerizable with acrylic acid, and 5 to 50% by weight. A water-based printing ink composition for laminating, comprising: 2. The binder resin as water-dispersible,
90 to 70% by weight of self-emulsifying and water-soluble polyurethane resin having an acid value of 20 to 100, water-dispersible ethylene-
The aqueous printing ink composition for laminating according to claim 1, which contains 10 to 30% by weight of an acrylic acid copolymer. 3. The aqueous printing ink composition for laminating according to claim 1, wherein the ethylene-acrylic acid copolymer has a melt index of 300 to 1000 g / 10 minutes.