JPH07138514A - Radiation-curable water-based printing ink composition - Google Patents

Abstract

PURPOSE:To obtain the composition excellent in material properties including solvent, chemical and water resistances. CONSTITUTION:An emulsion of a polyurethane having active amino groups is reacted with an isocyanate having a polymerizabie unsaturated group (a) in the presence of water to obtain the composition, in which the group (a) has been incorporated into the polyurethane skeleton. Due to this molecular structure, the polymer can form a dense network structure upon irradiation. Thus, a cured coating film which is not brittle and is tenaciously adherent to the substrate is obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a radiation-curable aqueous printing ink composition which is polymerized by irradiation with UV light.

[0002]

Resins such as polyurethane, polyamide, nitrocellulose and polyester are used as binders in printing inks used for various plastic films, metal foils and the like. These resins are used alone or in combination, and are used after being dissolved in an organic solvent. In this organic solvent type ink, the binder itself has water resistance, and by obtaining a crosslinked ink film using an isocyanate compound or an epoxy compound, excellent physical properties such as solvent resistance and chemical resistance can be obtained. It is expressed.

On the other hand, in recent years, radiation curable resins which are polymerized by various kinds of radiation such as ultraviolet rays and electron beams have the advantages that they can be processed in energy saving, low temperature and short time. Therefore, their application to printing ink has been studied. There is. Among the radiation-curable printing ink compositions according to the prior art, non-aqueous type ink compositions are predominant. Since these radiation curable resins are directed to energy saving, low temperature, and short-time processing as described above, 100% of the constituent components are composed of resin components, and the mainstream of them is the radiation curable resin in the medium molecular weight range. It contains a large amount of a low-molecular component of a monomer for adjusting viscosity for improving coating suitability, that is, a so-called reactive diluent monomer. Examples of the reactive diluent monomer include vinyl acetate, vinylpyrrolidone, alkyl acrylic ester and the like.

[0004]

However, these printing inks have the risk of fire due to organic solvents, and
It has a problem of polluting the atmosphere. It is also not preferable from the viewpoint of resource saving. Therefore, water-based printing inks excellent in physical properties such as solvent resistance, chemical resistance and water resistance, which are alternatives to these organic solvent type inks, have been actively developed.

In aqueous printing inks, styrene-maleic acid copolymer resins, styrene-acrylic copolymer resins, acrylic resins and the like are generally used as binders. However, when printing is performed using a water-based ink that uses a binder made of these resins, it is pointed out that the physical properties such as water resistance, solvent resistance, and chemical resistance of the printed matter are extremely low in practical use. ing.

In order to obtain sufficient physical properties such as solvent resistance, chemical resistance and water resistance, an epoxy compound,
It is known that a certain degree of physical properties can be obtained by adding a crosslinking agent such as a carbodiimide compound and drying and then crosslinking the ink film. However, due to weak crosslinking between the functional groups of these aqueous binders and these crosslinking agents,
The current situation is that sufficient solvent resistance, chemical resistance, and water resistance have not been obtained.

Further, an aqueous urethane binder has been proposed because the flexibility of the resin and the adhesiveness to various materials are excellent. However, the conventional water-based urethane binder is basically an aqueous dispersion of a thermoplastic urethane, so that it is insufficient in terms of solvent resistance, chemical resistance, water resistance, etc. as described above, and further performance is improved. The current situation is that improvements are desired.

On the other hand, in a conventional printing ink composition using a radiation-curable resin, a low-molecular weight reactive diluent monomer for adjusting viscosity and film thickness is added in an amount of 20 to 70 parts by weight. Since it needs to be added to the molecular weight resin component,
The addition of this reactive diluting monomer causes a problem in safety control, and also causes a problem of odor pollution because it is harmful to the human body.

In order to reduce or completely eliminate the above drawbacks, it is an important subject to take chemical and industrial measures. A simple method to solve this problem is to reduce the amount of reactive diluent monomer used by adding water, but since the radiation-curable resin in the prior art is insoluble in water, a small amount of water is used. Although it can be used and compounded, it cannot be compounded in a large amount and cannot be fundamentally solved. As a chemical method for solving this point, it is the current situation that the radiation curable ink composition is made water-based.

The present invention has been made in order to solve the above problems of the prior art, and an object of the present invention is to have excellent physical properties such as solvent resistance, chemical resistance and water resistance, and to prevent radiation. An object is to provide an aqueous printing ink composition that can be cured.

[0011]

The radiation-curable water-based printing ink composition of the present invention is a radiation-curable polyurethane obtained by reacting an active amino group-containing polyurethane emulsion with a polymerizable unsaturated group-containing isocyanate compound. It is characterized by containing an aqueous dispersion and a photosensitizer.

The radiation curable polyurethane aqueous dispersion used in the present invention can be produced by the following method.

The active amino group-containing polyurethane emulsion used here is a urethane prepolymer having an isocyanate group at the molecular end obtained by reacting a compound containing two or more active hydrogens with an organic polyisocyanate. Disperse, and then in the presence of water, at least two primary amino groups and at least one in the same molecule.
It is obtained by adding and reacting a polyamine having one secondary amino group.

Further, when the polyamine is added to the urethane prepolymer, the molar ratio of (terminal NCO group of the urethane prepolymer) / (primary amino group of the polyamine) is 1/1 to 1 / 0.7. It is preferable to carry out so as to be within the range.

The radiation-curable aqueous polyurethane dispersion used in the ink composition of the present invention can be obtained by adding a polymerizable unsaturated group-containing isocyanate to the above-mentioned active amino group-containing polyurethane emulsion and reacting it. The preparation of the polyurethane emulsion containing the active amino group facilitates the introduction of the polymerizable unsaturated group into the urethane skeleton. The active amino group-containing polyurethane emulsion is obtained by reacting a urethane prepolymer having an isocyanate at the molecular end with a polyamine having at least two primary amino groups and at least one secondary amino group in the same molecule. The production of the urethane prepolymer having isocyanate at the molecular end is carried out in a system in which the compound containing two or more active hydrogens and the organic polyisocyanate are in excess.

The above-mentioned compound containing two or more active hydrogens is a compound containing two or more hydroxyl groups at the terminal or in the molecule, and is a generally known polyether, polyester, polycarbonate, polyetherester, polythioether, Examples thereof include polyol compounds such as polyacetal, polybutadiene, and polysiloxane. The molecular weight of the compound containing two or more active hydrogens is 50
It is preferably in the range of 0 to 5,000. If necessary, low molecular weight 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, ethylene glycol, butanediol, neopentyl glycol, diethylene glycol, trimethylolpropane, cyclohexane. Glycol such as dimethanol or triol may be used.

As the organic polyisocyanate compound, an aromatic, aliphatic or alicyclic organic polyisocyanate which has been conventionally used is used. For example, organic polyisocyanates such as tolylene diisocyanate, diphenyl methane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexyl methane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl xylylene diisocyanate or mixtures thereof. Can be given.

The reaction between the compound containing two or more of these active hydrogens and the excess amount of the organic polyisocyanate is carried out by a conventionally known one-step or multi-step isocyanate polyaddition reaction method under the temperature condition of 50 to 120 ° C. Done in.

In this reaction, if necessary, a reaction control agent such as phosphoric acid, adipic acid, benzoyl chlorite, a reaction catalyst such as dibutyltin dilaurate, stannas octoate, triethylamine, and an organic solvent that does not react with an isocyanate group. May be added during or after the reaction. Examples of these organic solvents include acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, ethyl acetate, toluene and xylene.

Although it is possible not to use an organic solvent at all, when the urethane prepolymer is used for dilution due to its high viscosity, etc., after preparation of the active amino group-containing polyurethane emulsion described below or the active amino group-containing polyurethane. After the reaction between the emulsion and the isocyanate compound containing a polymerizable unsaturated bond is completed, it can be recovered under reduced pressure.

Considering the concern about the polymerization of the polymerizable unsaturated group due to the recovery under reduced pressure, the solvent is recovered after the preparation of the active amino group-containing polyurethane emulsion, that is, before the introduction of the polymerizable unsaturated group into the polyurethane skeleton. Preference is given to carrying out in process.

In the present invention, since the active amino group-containing polyurethane is used as an aqueous emulsion, it is necessary to consider the solvent recovery described later. Considering this, acetone, methyl ethyl ketone, and ethyl acetate are preferable as the solvent, and considering the emulsification and dispersion of the urethane polymer described below in water, acetone and methyl ethyl token are preferable. Further, considering the control of the reaction between the emulsified and dispersed urethane prepolymer and the polyamine compound described later, ethyl acetate is preferable. More preferably, these solvents are selected for each case.

If desired, a stabilizer such as an antioxidant can be added during the reaction or after the reaction. The urethane polymer obtained here has a terminal isocyanate group content of 3 to 0.3% by weight, and more preferably,
It is desirable to set it to 2-1%. If the content of the terminal isocyanate group is more than 3% by weight, emulsion destruction and gelation occur during the reaction with the polyamine described below, or product stability and stability over time become poor, and the terminal isocyanate group content is 0.3. If it is less than 10% by weight, the amount of the active amino group introduced by the polyamine described below will be small, and as a result, the amount of the polymerizable unsaturated group-containing isocyanate to be introduced in the reaction of the subsequent step will be small and the polymerization introduced into the urethane skeleton. The amount of the unsaturated group is reduced. Therefore, the radiation-curable polyurethane aqueous dispersion used in the present invention induces a problem that the physical properties of the coating film after radiation curing cannot be expected to be improved.

The urethane prepolymer having an isocyanate group at the molecular end is emulsified and dispersed in water. In this dispersion, when the urethane prepolymer itself has dispersibility, it is added to water as it is. When the urethane prepolymer does not have self-dispersibility, the following method can be adopted as a treatment method performed before dispersing in water.

[0025]. In the above-mentioned urethane prepolymer preparation step, a polyol component containing a carboxyl group in the molecule in advance,
For example, a carboxyl group has been introduced by the reaction of dimethylolpropionic acid and the like with an organic polyisocyanate, and the carboxyl group is a basic compound such as triethylamine, trimethylamine, diethanolmonomethylamine, diethylethanolamine, caustic soda, and caustic potassium. A method in which the salt is converted to a salt of a carboxyl group.

.. In the above-mentioned urethane prepolymer preparation stage, 5 wt% or more of oxyethylene chain was previously contained in the molecule, and a nonionic activator having an HLB value of 6 to 18 was added and mixed at 50 ° C. or lower after preparation of the urethane prepolymer. how to. However, the amount of the activator used is preferably 15% by weight or less based on the urethane prepolymer in consideration of the emulsification dispersibility, the water resistance of the product film, and the like.

.. After the above urethane prepolymer preparation,
50 to 5% of the terminal isocyanate groups is more preferable, and 3
Aqueous solution of sodium ethane such as aminoethanesulfonic acid, aminoacetic acid, etc. corresponding to 0 to 5%, potassium salt solution at 5 to 50 ° C.
Preferred is a method of reacting at 20 to 40 ° C. for 60 minutes. These treatments are not necessary when the urethane prepolymer itself has dispersibility as described above.

Water is added to the urethane prepolymer that has been subjected to any of the above treatments, or in the case of a urethane prepolymer having self-dispersibility, water is added without subjecting these treatments to a homomixer, homogenizer, etc. Emulsification and dispersion is carried out using the above emulsification and dispersion device. When emulsifying and dispersing, in order to suppress the reaction between the terminal isocyanate group of the urethane prepolymer and water, the emulsifying and dispersing temperature is preferably low, 5 to 40 ° C, preferably 5 to 30 ° C.
It is more preferably carried out in the range of 5 to 20 ° C.

Next, the polyamine compound used in the present invention has at least two primary amino groups in the same molecule.
And a compound having at least one secondary amino group are used, and examples thereof include diethylenetriamine, triethylenetetramine, and dipropylenetriamine.
These polyamine compounds are used in such an amount that the ratio of (the number of terminal isocyanate groups of the urethane prepolymer) / (the number of primary amino groups of the polyamine) is 1/1 to 1 / 0.7. Can be decided If this ratio is less than 1/1 (large molar ratio of primary amino groups), effective high molecular weight tends to be hindered, and larger than 1 / 0.7 (small molar ratio of primary amino groups). , The amount of active amino groups introduced is reduced, the amount of polymerizable unsaturated groups introduced in the next step is necessarily reduced, and the effect of exhibiting physical properties of the emulsion composition of the present invention is reduced, and the emulsion is It is not preferable because the composition thickens and gels.

After the above urethane prepolymer is emulsified and dispersed in water, the above polyamine compound is added and the terminal isocyanate group of the urethane prepolymer and polyamine are reacted in an emulsified and dispersed system. In carrying out this reaction, an emulsifying and dispersing device such as a homomixer or a homogenizer is used to carry out a uniform reaction. Further, in consideration of gelation caused by rapid reaction, emulsion destruction due to local reaction, etc., product stability afterwards, and stability over time, 5 to 40 ° C, preferably 5 to 30 ° C, more preferably 5 The reaction is carried out in the temperature range of -20 ° C, and the polyamine chain extension reaction is usually carried out for 10 to 120 minutes.

According to this method, the primary amino group in the polyamine compound molecule, which has a faster reaction rate with respect to the isocyanate group, selectively participates in the chain extension reaction. As a result, the site of the secondary amino group in the polyamine compound molecule is introduced into the polyurethane skeleton structure. In this way, the active amino group-containing polyurethane emulsion used in the present invention is produced.

At this time, phosphoric acid, hydrochloric acid, benzoyl chloride or the like can be added in order to suppress the side reaction between water and the isocyanate group and accelerate the reaction between the isocyanate group and the polyamine compound.

Next, the polymerizable unsaturated isocyanate used in the preparation of the aqueous printing ink composition of the present invention is exemplified by hexamethylene diisocyanate, xylylene diisocyanate, cyclohexylmethane diisocyanate, isophorone diisocyanate, tolylene diisocyanate, General organic polyisocyanates such as diphenylmethane diisocyanate or dimers or trimers thereof, and acryloyl group-containing hydroxyl group compounds such as hydroxyl methacrylate and hydroxyl acrylate, and / or their alkylene oxide adducts, or allyl alcohol and And / or an addition reaction product of allyl alcohol with an alkylene oxide adduct. Other examples include 2-methacryloyloxyethyl isocyanate represented by the structural formula of Chemical formula 1, methacryloyl isocyanate represented by the structural formula of Chemical formula 2, and the like.

[0034]

[Chemical 1]

[0035]

[Chemical 2]

These polymerizable unsaturated group-containing isocyanate compounds are added to the active amino group-containing polyurethane emulsion obtained in the above-mentioned step, more preferably added dropwise and mixed to carry out the reaction.

The reaction of addition of the polymerizable unsaturated group-containing isocyanate compound to the active amino group-containing polyurethane emulsion is carried out at a temperature of 5 to 40 ° C., more preferably 5 to 30 ° C. for 15 minutes to 120 minutes. Will be implemented. If the reaction temperature is lower than 5 ° C, the reaction between the active amino group and the polymerizable unsaturated group-containing isocyanate compound is delayed, and a side reaction between the polymerizable unsaturated group-containing isocyanate compound and water occurs, which is not preferable. On the other hand, when the reaction temperature is higher than 40 ° C., a side reaction between the polymerizable unsaturated group-containing isocyanate compound and water is induced, so that the reaction rate between the active amino group and the polymerizable unsaturated group-containing isocyanate compound decreases. . Therefore, the amount of the polymerizable unsaturated group introduced into the urethane skeleton is necessarily reduced.

The amount of the polymerizable unsaturated group-containing isocyanate compound added is (the number of moles of the active amino group of the active amino group-containing polyurethane emulsion) / (the number of moles of the isocyanate group of the polymerizable unsaturated group-containing isocyanate compound). Is added such that the ratio of is 1.05 to 1 / 0.8. When this ratio is smaller than 1 / 1.05 (the molar ratio of isocyanate groups is large), the polymerizable unsaturated group-containing urea body in the free state due to the reaction between the polymerizable unsaturated group-containing isocyanate compound and water, It is not preferable because the amount of the saturated group-containing amine compound increases. Also,
If this ratio is larger than 1 / 0.8 (the molar ratio of isocyanate groups is small), the amount of the polymerizable unsaturated groups introduced will inevitably decrease, and the effect of exhibiting physical properties of the emulsion composition of the present invention will decrease. It is not preferable. Furthermore, if a large amount of active amino groups remain, burning and yellowing of the film after curing are increased, which is not preferable.

By the above reaction, the active amino group in the urethane skeleton of the polyurethane contained in the aqueous printing ink composition of the present invention reacts with the isocyanate group in the polymerizable unsaturated group-containing isocyanate compound, and finally A polymerizable unsaturated group is introduced into the polyurethane skeleton. This gives the radiation-curable polyurethane water dispersion used in the present invention.

Next, the photosensitizer used in the present invention will be described. As the photosensitizer, acetophenone type, benzoin ether type, ketal type, benzophenone type,
Examples thereof include anthraquinone-based derivatives. For example, 2
-Hydroxy-2-methyl-1-phenylpropane-1
-One, alkyl benzoin ethers such as isopropyl benzoin ether, methyl orthobenzoyl benzoate, benzyl methyl ketal, ethyl anthraquinone and the like. These photosensitizers may be used alone or
You may use together 1 or more types.

The amount of addition is 0.3% based on the solid content of the radiation-curable polyurethane water dispersion in order to achieve photocrosslinking.
It is -10%, preferably 0.3-5%. Further, these photosensitizers are added as it is or after being emulsified in water using an emulsifier and then added to the radiation-curable polyurethane aqueous dispersion.

[0042]

The radiation-curable aqueous printing ink composition of the present invention comprises a radiation-curable polyurethane aqueous dispersion having a polymerizable unsaturated group in the polyurethane skeleton and a photosensitizer as essential components.

Therefore, photo-crosslinking is caused by irradiation with UV light to form a structure having a high crosslink density. Therefore, performances such as water resistance, solvent resistance, and chemical resistance, which are the drawbacks of the conventional polyurethane emulsion having no reactive group, are improved.

Since the radiation-curable aqueous printing ink composition of the present invention is an aqueous emulsion, that is, water is used as a diluting medium, viscosity control and film thickness adjustment can be easily performed. Therefore, the problem of residual odor peculiar to the monomer after curing caused by the reactive diluent monomer used together with the radiation curable resin of the prior art for viscosity control and film thickness adjustment, and the adhesion caused by resin curing shrinkage. It becomes possible to solve problems such as insufficient adhesion to materials.

When it is necessary to increase the hardness of the cured film, the radiation-curable polyurethane emulsion composition of the present invention can be used in combination with a water-soluble reactive diluent monomer. Examples of the water-soluble reactive diluent monomer include dimethylacrylamide, vinylpyrrolidone, ethylene glycol, diacrylate of diethylene glycol, and diacrylate of low-molecular polyethylene glycol.

[0046]

The radiation-curable aqueous printing ink composition according to the present invention has the following unique effects.

The radiation-curable aqueous printing ink composition of the present invention comprises a radiation-curable polyurethane aqueous dispersion having a polymerizable unsaturated group in the polyurethane skeleton and a photosensitizer as essential components. Therefore, photo-crosslinking is caused by UV light irradiation, and a structure with high energy saving and high crosslink density is formed. Therefore, performances such as water resistance, solvent resistance, and chemical resistance, which are defects of the conventional polyurethane emulsion having no reactive group, are improved.

Since it is an aqueous emulsion, the viscosity can be adjusted by adding water to adjust the ink film thickness and the like. Therefore, problems such as residual monomer odor after curing caused by a monomer as a reactive diluent that is also used for dilution with conventional radiation curable resin, and insufficient adhesion to the adherend due to resin curing shrinkage Is solved.

[0049]

EXAMPLES The present invention will be described below with reference to the agents, but the present invention is not limited to these examples. still,
"Parts" and "%" in Examples, Synthesis Examples, Comparative Examples and Comparative Synthesis Examples, which will be described later, represent parts by weight and% by weight, respectively, unless otherwise specified.

<Synthesis example> Polyester polyol (butylene adipate, molecular weight 2000) 350 parts, trimethylol propane 10.1 parts, polyethylene glycol 3
5 parts (molecular weight 600), PO (propylene oxide)
/ EO (ethylene oxide) random copolymer polyether polyol 35 parts, (PO / EO = 30/70, molecular weight 3400), and 1,4-butanediol 78.3.
Parts to 400 parts of methyl ethyl ketone and dissolved,
310 parts of isophorone diisocyanate are used to bring the system temperature to 50 ° C.
Added in. Then, dibutyl tin dilaurate 0.0
5 parts are added, and the system temperature is gradually raised to 75 ° C.
When the reaction was carried out at 75 ° C. for 60 minutes, 0.05 part of dibutyltin dilaurate was added. After that, the reaction was continued and cooled at the time of 75 ° C./200 minutes, and the system temperature was adjusted to 50 ° C. The free isocyanate group of the urethane prepolymer after cooling to 50 ° C. was 2.0% (relative to solid content).

Next, at an internal temperature of 45 ° C., 80 parts of a polyoxyethylene allylphenol ether type nonionic surfactant (HLB = 15), which is an ethylene oxide adduct of distyrenated phenol, was added and mixed for 10 minutes. . After that, the contents in the system are heated to 300 using a homomixer.
The mixture was stirred at 0 rpm at high speed, 1300 parts of distilled water was gradually added thereto, and then emulsification was carried out at a system temperature of 30 ° C. for 20 minutes.

After cooling the system temperature to 20 ° C., an aqueous solution of diethylenetriamine in which 18 parts of diethylenetriamine was dissolved in 130 parts of distilled water was added. System temperature is 2
The temperature was controlled to 0 to 25 ° C., and stirring was continued for 60 minutes using a homomixer at 3000 rpm. Next, methyl ethyl ketone used as a solvent was recovered under reduced pressure (water bath 40 ° C.) by an evaporator. As described above, the active amino group-containing polyurethane emulsion used in the present invention could be prepared.

The active amino group-containing polyurethane emulsion obtained was analyzed. The results are shown in Table 1. Amount of active amino groups contained (amine value, hereinafter “Am · V”)
10 parts of the emulsion was stirred and dissolved in 300 parts of N-methyl-2-pyrrosodone, and titrated with hydrochloric acid using bromphenol blue as an indicator.

[0054]

[Table 1]

Next, 1000 parts of the active amino group-containing polyurethane emulsion obtained above is kept at a system temperature of 25 ° C. and stirred at 1000 rpm by a homomixer. Hydroquinone monomethyl ether 0.2
After adding a solution of 2 parts of isoproalcohol dissolved in 2 parts of 2-methacryloyloxyethyl isocyanate 1
0.2 part was gradually added dropwise over 10 minutes. afterwards,
Stirring was continued at 25 ° C., and stirring was continued until the measured value of Am · V became constant.

As a result, stirring for 60 minutes is required, and Am.V
The value was 0.25 (for all systems), and it is clear that the active amino groups in the active amino group-containing polyurethane emulsion and the isocyanate groups of 2-methacryloyloxyethyl isocyanate have reacted. As a result, a white liquid emulsion having a solid content of 40.2% was obtained.

<Comparative Synthesis Example> A urethane prepolymer having a free isocyanate group of 2.0% was prepared in the same manner as in the example. After that, emulsification was carried out in the same manner as in Example, and then ethylenediamine was added in the same molar amount instead of diethylenetriamine and stirred. Next, the solvent used, methyl ethyl ketone, was recovered by an evaporator. From the above,
A polyurethane emulsion according to the prior art was obtained.
The analysis results of this polyurethane emulsion are also shown in Table 1. As can be seen from the amino group content in Table 1, this polyurethane emulsion has almost no active amino groups.

<Examples 1 and 2, Reference Example> Phthalocyanine blue TGR-1 (manufactured by Dainippon Ink and Chemicals, Inc.) as a pigment was added to the polyurethane emulsion obtained in the synthesis example.
Was mixed so as to be resin solid content / pigment = 3/1 and kneaded to obtain an aqueous printing ink. This water-based printing ink was used as the water-based printing ink of the reference example.

The radiation-curable water-based printing ink of Example 1 was prepared by adding 1% by weight of the photosensitizer shown in Chemical formula 3 to the resin solid content to the water-based printing ink of Reference Example. This was used as the aqueous printing ink of Example 2. The photosensitizer is added as an aqueous solution, and the composition of the aqueous solution contains the photosensitizer, a polyoxyethylene allylphenol ether type nonionic surfactant (HLB = 15) and water, and the ratio is 10 parts. / 8 copies / 82 copies.

[0060]

[Chemical 3]

Comparative Example The same amount of phthalocyanine blue TGR-1 (manufactured by Dainippon Ink and Chemicals, Inc.) as in Examples 1 and 2 was added to the conventional polyurethane emulsion obtained in Comparative Synthesis Example and kneaded. did. The obtained product was used as a water-based printing ink of Comparative Example.

<< Evaluation of Physical Properties of Ink Film >> Examples 1 and 2,
The physical properties of the ink film obtained using the water-based printing inks of Reference Example and Comparative Example were evaluated.

A corona discharge-treated surface of a corona discharge-treated stretched polypropylene film having a thickness of 20 μm has a film thickness of 5 μm.
The water-based printing inks of Examples 1 and 2, Reference Examples, and Comparative Examples were applied so as to obtain m and left in a dryer at 40 ° C. for 24 hours, and then a high pressure mercury lamp (irradiation intensity 80 W / cm ² ,
A test piece was prepared by performing photopolymerization by ultraviolet irradiation at a speed of 5 m / min using a focal point distance of 8 cm). The adhesiveness, solvent resistance, and water resistance of the printed surface of each test piece were evaluated, and the results are shown in Table 2. The test method and evaluation criteria are as follows.

[0064]

[Table 2]

<Adhesiveness> A peeling test of a test piece was performed using a Nichiban cellophane tape. The evaluation criteria are as follows.

◎ It does not peel even if it is suddenly separated. ○ Intermediate adhesive strength between ◎ and △ △ It peels if it is rapidly separated, but it does not peel when gradually separated. × It peels even when gradually separated. <Solvent resistance> Put ethanol on the printed surface of the test piece,
After 30 minutes, the surface condition was determined by rubbing with absorbent cotton (using Gakushin type fastness tester). The evaluation criteria are as follows.

○ The ink film is retained even after 30 times. △ The ink film disappears after 10 to 30 times. × The ink film disappears after 10 times or less. <Water resistance> The test piece is immersed in warm water at 60 ° C for 30 minutes. After that, the surface condition of the ink film was judged. The evaluation criteria are as follows.

○ Transparent and clear print color △ Partially whitened, print color partially unclear × Whitened and print color unclear From Table 2, the radiation-curable polyurethane aqueous dispersions of Examples 1 and 2 were obtained. The ink film obtained by using the water-based printing ink containing the photosensitizer has improved adhesiveness, warm water resistance and solvent resistance by UV irradiation, as is clear from comparison with the ink of Reference Example. I understand. This is because the polymerizable unsaturated group of the radiation-curable polyurethane undergoes a crosslinking reaction upon irradiation with light. On the other hand, the ink film obtained using the conventional polyurethane emulsion of Comparative Example is inferior to Examples 1 and 2 in terms of adhesion, hot water resistance and solvent resistance.

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Claims (3)

[Claims] 1. A radiation-curable aqueous polyurethane dispersion obtained by adding and reacting a polymerizable unsaturated group-containing isocyanate compound to an active amino group-containing polyurethane emulsion, and a photosensitizer. A radiation-curable aqueous printing ink composition. 2. The active amino group-containing polyurethane emulsion is obtained by emulsifying and dispersing in water a urethane prepolymer having an isocyanate group at the molecular end, which is obtained by reacting a compound containing two or more active hydrogens with an organic polyisocyanate. The radiation-curable composition according to claim 1, wherein a polyamine having at least two primary amino groups and at least one secondary amino group in the same molecule is then added and reacted. Aqueous printing ink composition. 3. The addition of the polyamine to the urethane prepolymer comprises:
The radiation-curable aqueous printing according to claim 2, wherein the molar ratio of (CO group) / (primary amino group of the polyamine) is in the range of 1/1 to 1 / 0.7. Ink composition.