JP2003321636A - Active energy beam-curable resin composition for flexo graphic ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy beam-curable resin composition for flexo graphic ink which is suitably usable for an active energy beam-curable type flexo graphic ink excellent in a transfer property when printed and scarcely forming a pinhole. <P>SOLUTION: The resin composition for active energy beam-curable flexo graphic ink is obtained by dissolving (A) an epoxyester resin obtained by reacting an epoxy resin having ≤700 g/eq epoxy equivalent with a monocarboxylic acid as essential components in (B) a bi- or more multifunctional (meth)acrylate. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active energy ray-curable resin composition for flexo ink.

[0002]

2. Description of the Related Art In flexographic printing, a plate material made of rubber or plastic is easy to make, and the cost required for printing is low. It is used for a wide range of printing up to penetrative fabric. So far, in flexographic printing, solvent-based flexographic inks that use a varnish prepared by dissolving a resin in a solvent have been mainly used, but due to increasing environmental awareness, an active energy ray-curable resin composition containing no solvent is used. The use of flexo ink consisting of is increasing. Conventionally, a mixture of various acrylates and methacrylates and prepolymers such as urethane acrylate and polyester acrylate has been used as an active energy ray-curable resin composition. However, the flexographic inks made of these resin compositions have the disadvantage that pinholes are generated during printing due to poor transferability.

[0003]

An object of the present invention is to provide an active energy ray curable flexo ink resin composition which is excellent in transferability during printing and can be preferably used for flexo ink in which pinholes are less likely to occur. is there.

[0004]

As a result of intensive studies to solve the above problems, the present inventor found that the epoxy equivalent was 70.
From an active energy ray-curable flexo ink resin composition obtained by dissolving an epoxy ester resin obtained by reacting an epoxy resin of 0 g / eq or less with a monocarboxylic acid in a bifunctional or higher functional (meth) acrylate. It was found that the flexographic ink obtained had good transferability and was less likely to cause pinholes during printing, and completed the present invention.

That is, the present invention has an epoxy equivalent of 700 g.
It is characterized in that an epoxy ester resin (A) obtained by reacting an epoxy resin having a ratio of / eq or less with a monocarboxylic acid as an essential component is dissolved in a bifunctional or higher functional (meth) acrylate (B). A resin composition for an active energy ray-curable flexo ink is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below.
The epoxy ester resin (A) used in the present invention may be any one obtained by reacting an epoxy resin (a1) having an epoxy equivalent of 700 g / eq or less with a monocarboxylic acid (a2) as an essential component, and is particularly limited. Not done.

The epoxy resin (a1) used in the present invention is
Has two or more epoxy groups and has an epoxy equivalent of 700 g /
It must be eq or less. Epoxy equivalent is 70
When it exceeds 0 g / eq, the viscosity of the ink becomes high, and the transfer failure of the ink occurs during printing. Epoxy resin (a1)
Can be prepared by the Taffy method for directly synthesizing a resin, the melting method in which the reaction is performed in two steps, or the oxidation method. Examples of the epoxy resin (a1) include bisphenol A diglycidyl ether and bisphenol A diβ.
Methyl glycidyl ether, bisphenol F diglycidyl ether, tetrahydroxyphenylmethane tetraglycidyl ether, resorcinol diglycidyl ether, brominated bisphenol A diglycidyl ether,
Glycidyl such as chlorinated bisphenol A diglycidyl ether, novolac glycidyl ether, polyalkylene glycol diglycidyl ether, hydrogenated bisphenol A glycidyl ether, diglycidyl ether of bisphenol A alkylene oxide adduct, glycerin triglycidyl ether, pentaerythritol diglycidyl ether Ether type epoxy resin; glycidyl ether / ester type epoxy resin such as p-oxybenzoic acid glycidyl ether ester; phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, dimer acid diglycidyl ester Glycidyl ester type epoxy resins such as esters; glycidyl aniline, tetraglycidyl di Glycidylamine type epoxy resins such as minophenylmethane and triglycidyl isocyanurate; linear aliphatic epoxy resins such as epoxidized polybutadiene and epoxidized soybean oil; 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexane Examples thereof include alicyclic epoxy resins such as carboxylate and 3,4 epoxycyclohexylmethyl (3,4-epoxycyclohexane) carboxylate. These epoxy resins (a1) can be used alone or in combination of two or more kinds.

The epoxy resin (a1) has a transition property,
To obtain a flexo ink with good curability and emulsification characteristics,
It is preferable to use a bisphenol A type epoxy resin. Examples of the bisphenol A type epoxy resin include the above-mentioned bisphenol A diglycidyl ether,
Examples thereof include bisphenol A diβ-methyl glycidyl ether, brominated bisphenol A diglycidyl ether, chlorinated bisphenol A diglycidyl ether, hydrogenated bisphenol A glycidyl ether, and diglycidyl ether of bisphenol A alkylene oxide adduct.

The epoxy equivalent of the epoxy resin (a1) is
The range of 100 to 700 g / eq is preferable, and 100 to 4
The range of 00 g / eq is more preferable.

Examples of the monocarboxylic acid (a2) include linseed oil fatty acid, soybean oil fatty acid, safflower oil fatty acid, castor oil fatty acid, millet oil fatty acid, tall oil fatty acid,
Lauric acid, tridecyl acid, myristic acid, pentadecyl acid, palmitic acid, hepradecyl acid, stearic acid,
Fatty acids such as isostearic acid, nonadecanoic acid, oleic acid, elaidic acid, and ceretic acid; rosin, hydrogenated rosin, benzoic acid, paratertiarybutylbenzoic acid, and caproic acid can be mentioned. Monocarboxylic acid (a2)
As the above, a monocarboxylic acid having 4 to 25 carbon atoms is preferable, and a hydrogenated rosin is particularly preferable. The monocarboxylic acid (a2) can be used alone or in combination of two or more kinds.

The epoxy ester resin (A) is, for example,
It can be prepared by a method in which an epoxy resin (a1) having an epoxy equivalent of 700 g / eq or less and a monocarboxylic acid (a2) are essentially mixed and reacted under heating in a nitrogen atmosphere.

As a device used for preparing the epoxy ester (A), a batch type production device such as a reaction vessel equipped with a nitrogen inlet, a thermometer, a stirring device, a rectification column and the like can be preferably used. An extruder equipped with a degassing port, a continuous reaction device, a kneader, or the like can also be used. Further, if necessary, a known and commonly used catalyst that accelerates the reaction between the epoxy group and the carboxyl group may be used.

The temperature at which the epoxy resin (a1) is reacted with the monocarboxylic acid (a2) is 80 ° C to 200 ° C.
The temperature may be 100 ° C to 160 ° C.

The amount of the epoxy resin (a1) and the monocarboxylic acid (a2) used in preparing the epoxy ester resin (A) is determined by the number of moles of the monocarboxylic acid (a2) and the epoxy group of the epoxy resin (a1). When the ratio (COOH / epoxy group) to the number of moles is 1.5 / 1 to 0.7 / 1, the emulsification characteristics, curing characteristics, and stability over time of the flexo ink are good, and the flexo ink The viscosity is also suitable because it is suitable for printing, among which 1.2 / 1 to 0.
The range of 8/1 is particularly preferred.

The epoxy ester resin (A) improves adhesiveness and curability when the active energy ray-curable flexo ink resin composition of the present invention is made into an ink.
An epoxy ester resin modified with a secondary amine and / or a polycarboxylic acid may be used.

The epoxy ester resin modified with a secondary amine and / or a polycarboxylic acid is, for example, a monocarboxylic acid obtained by reacting the epoxy resin (a1) with a secondary amine and / or a polycarboxylic acid. (A2) is reacted, the epoxy resin (a1) is reacted with the monocarboxylic acid (a2), and then a secondary amine and /
Alternatively, it can be prepared by a method of reacting a polycarboxylic acid, a method of mixing a secondary amine and / or a polycarboxylic acid, a monocarboxylic acid, (a2), and an epoxy resin (a1) and reacting them. For preparing the epoxy ester resin modified with a polycarboxylic acid, the method is preferred.

Examples of secondary amines include diethylamine, dipropylamine, dibutylamine and the like.

Examples of the polycarboxylic acid include terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, succinic acid, Saturated polybasic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, 1,4-cyclohexanedicarboxylic acid and hexahydrophthalic anhydride; unsaturated such as maleic anhydride, fumaric acid, itaconic acid and tetrahydrophthalic anhydride Polybasic acids; dodecenyl succinic anhydride, tetrahydrophthalic anhydride and the like.

The reaction between the epoxy group and the secondary amine in the preparation of the epoxy ester resin modified with the secondary amine does not impair the emulsifying properties when it is made into an ink, so that the molar ratio of the epoxy group and the amino group is large. (Epoxy group / amino group)
Are preferably reacted at a ratio of (1 / 0.01) to (1 / 0.7), and (1 / 0.05) to (1/0.
5) is more preferable.

The reaction between the epoxy group and the polyvalent carboxylic acid when preparing the epoxy ester resin modified with the polyvalent carboxylic acid is such that the reaction product is less likely to gel, and the emulsifying property of the ink when made into an ink is In order not to damage it, it is preferable to react at a molar ratio of epoxy group and carboxyl group (epoxy group / carboxyl group) of (1 / 0.02) to (1 / 1.5). .1) to (1 /
1) is more preferable.

The reaction method of the epoxy group and the secondary amine or polycarboxylic acid is not particularly limited, and various methods can be used. The reaction temperature is usually about 60 to 200 ° C., preferably 80 ° C. or higher to prevent unreacted substances from remaining, and 170 ° C. or lower to prevent gelation of the reaction product.

The bifunctional or higher functional (meth) acrylate (B) which dissolves the epoxy ester resin (A) is, for example, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth). Acrylate, polypropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, hydroxypivalate neopentyl glycol Di (meth) acrylate, bisphenol A ethylene oxide adduct di (meth) acrylate, bisphenol A propylene oxide adduct di (meth) acrylate, 2,2'-di (hydroxypropoxyphenyi) Bi) (meth) acrylates such as di (meth) acrylate of propane and di (meth) acrylate of tricyclodecane dimethylol; morpholine acrylate, N-vinylpyrrolidone, N-vinylformamide, EO-modified phosphorus Bifunctional (meth) acrylates such as acid (meth) acrylate; trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, trimethylolethane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate. , Dipentaerythritol hexa (meth) acrylate, tetramethyloltetra (meth) acrylate, glycerin (meth) acrylate, tris ((meth) acryloxyethyl) isocyanurate, and ethylene oxide , Polyfunctional acrylate such as acrylic acid esters of polyols made by ring-opening addition of propylene oxide.

Bifunctional or higher functional (meth) acrylate (B)
As the above, a bifunctional to hexafunctional (meth) acrylate is preferable. The bifunctional or higher (meth) acrylate (B) may be used alone or in combination of two or more kinds, but it is particularly preferable to use a bifunctional or higher functional (meth) acrylate containing 90% by weight or more of the bifunctional or hexafunctional (meth) acrylate.

The active energy ray-curable flexo ink resin composition of the present invention is obtained by dissolving the epoxy ester resin (A) in a bifunctional or higher functional (meth) acrylate (B). Epoxy ester resin (A) and 2
The blending amount of the (meth) acrylate (B) having a functionality or higher is such that the weight ratio (A / B) of the epoxy ester resin (A) and the (meth) acrylate (B) having a functionality of 2 or more is used in order to obtain appropriate curability during printing. ) Is preferably 90/10 to 20/80, and more preferably 80/20 to 40/60.

As a method for dissolving the epoxy ester resin (A) in the bifunctional or higher functional (meth) acrylate (B) when preparing the active energy ray-curable flexo ink resin composition, an epoxy ester resin ( There is no particular limitation as long as it is a method in which A) can be dissolved in (meth) acrylate (B). For example, the epoxy ester resin (A) and the (meth) acrylate (B) may be mixed and then heated and dissolved, or the epoxy ester resin (A) and the (meth) acrylate (B) may be separately heated to form a solution. You may mix after shape | molding.

The melting temperature at the time of dissolution is preferably in the range of 80 to 120 ° C., but it is necessary that it is lower than the polymerization temperature of the (meth) acrylate (B), lower than the decomposition temperature, and lower than the polymerization temperature of the fatty acid. .

The active energy ray-curable flexo ink resin composition of the present invention preferably has a viscosity of 20 to 500 Pa · S, and 50 to 500, as measured by a Gardner foam viscometer.
Pa · S is more preferable. Here, the viscosity of the active energy ray-curable flexo ink resin composition means the total of epoxy ester resin (A) and (meth) acrylate (B) [(A) + (B)] and butyl acetate (C). And the weight ratio [(A) + (B)] / (C) of 4/1 is the viscosity measured using the Gardner-type foam viscometer method of JIS K5400.

The active energy ray-curable flexo ink resin composition of the present invention preferably contains a thermal polymerization inhibitor in order to prevent thermal polymerization during production and to maintain storage stability. Examples of the thermal polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, t-butylcatechol, p-benzoquinone, 2,5-t-butylhydroquinone, phenothiazine and the like. The blending amount is 0.01 to 1 with respect to the total weight of the epoxy ester resin (A) and the bifunctional or higher functional (meth) acrylate (B).
Weight percent is preferred.

The active energy ray-curable flexo ink resin composition of the present invention may contain a photoinitiator and a photosensitizer. As the photoinitiator and photosensitizer that can be used in the present invention, the photoinitiator and photosensitizer used in ordinary active energy ray-curable resin compositions can be used.

As the photoinitiator, for example, acetophenones, benzophenones, Michler's ketone, benzyl, benzoin ethers, benzyl dimethyl ketal, α-
Examples thereof include acyloxime esters, thioxanthones, anthraquinones and their derivatives, acylphosphine oxides and their derivatives. The photoinitiator can be used alone or in combination of two or more kinds. The amount used is 100 parts by weight in total of the epoxy ester resin (A) and the bifunctional or higher functional (meth) acrylate (B).
0.5 to 45 parts by weight is preferable, and 2 to 20 parts by weight is particularly preferable.

Examples of the photosensitizer include amines, ureas, sulfur compounds, nitriles, phosphorus compounds, nitrogen compounds, chlorine compounds and the like. The photosensitizer can be used alone or in combination of two or more kinds.
The amount used is preferably 0.5 to 45 parts by weight, and particularly 2 to 20 parts by weight, based on 100 parts by weight of the total of the epoxy ester resin (A) and the bifunctional or higher functional (meth) acrylate (B).
Part by weight is especially preferred.

Further, in the active energy ray-curable flexo ink resin composition of the present invention, a resin other than an oligomer or an epoxy ester (A) can be used if necessary. Examples thereof include polyester acrylate, urethane acrylate, rosin-modified epoxy acrylate, fatty acid-modified epoxy acrylate, polydiallyl phthalate resin, amino resin, benzoguanamine resin, alkyd resin, petroleum resin and the like.

When the resin composition of the present invention is made into an ink, various colorants, pigments, surface smoothing agents, defoaming agents, viscosity modifiers and the like can be added. To mix these with the resin composition of the present invention, a kneading machine such as a three-roll machine may be used.

[0034]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, "part" and "%" are based on weight unless otherwise specified.

Example 1 A reaction vessel equipped with a thermometer, a stirrer, and a nitrogen inlet tube was charged with 230 parts of hydrogenated rosin (Pine Crystal KR-85, manufactured by Arakawa Chemical Industry Co., Ltd.) and 0.9 part of triphenylphosphine. In addition, after elevating the temperature to 150 ° C. under a nitrogen atmosphere to dissolve it, an epoxy resin (manufactured by Dainippon Ink and Chemicals, Inc., EPICLON 850, epoxy equivalent 1
90 g / eq) of 120 parts was added, and an esterification reaction was carried out at 150 ° C. for 8 hours to obtain an epoxy ester resin. The acid value of this epoxy ester resin was 1 mgKOH / g or less. Epoxy ester resin is cooled to 100 ° C., dibutyl hydroxytoluene (BHT) 0.15
Part, hydroquinone monomethyl ether (MEHQ)
0.05 parts, propylene oxide (PO) modified neopentyl glycol diacrylate (PONPGDA)
(Photon 4127 manufactured by San Nopco Ltd.) 150
After adding parts, the epoxy ester resin was dissolved and then cooled to room temperature to obtain an active energy ray-curable flexo ink resin composition. This is varnish 1. Varnish 1
The viscosity according to the Gardner-type foam viscometer method of JIS K 5400 was 180 Pa · S.

Example 2 740 parts of hydrogenated rosin was added to the same reaction vessel as in Example 1, heated to 150 ° C. in a nitrogen atmosphere to dissolve the hydrogenated rosin, and then 430 parts of epoxy resin was added. In addition, esterification reaction was performed at 150 ° C. for 2.5 hours. 1
After cooling to 00 ° C. and adding 32 parts of dinormal butylamine, reaction was carried out at 150 ° C. for 3 hours (acid value 1 mg KO
H / g or less). Epoxy ester resin is cooled to 100 ° C., 0.3 parts BHT, 0.3 parts MEHQ, and PO
After 300 parts of NPGDA was added to dissolve the epoxy ester resin, it was cooled to room temperature to obtain an active energy ray curable flexo ink resin composition. This is varnish 2. The viscosity of the varnish 2 according to the JISK 5400 Gardner-type foam viscometer method was 150 Pa · S.

Example 3 770 parts of hydrogenated rosin was added to the same reaction vessel as in Example 1, heated to 150 ° C. in a nitrogen atmosphere to dissolve the hydrogenated rosin, and then 430 parts of epoxy resin was added. In addition, an esterification reaction was performed at 150 ° C. for 2.5 hours. Then, after adding 22 parts of maleic anhydride, 150
The reaction was carried out at ℃ for 7 hours (acid value 1 mgKOH / g or less).
Epoxy ester resin is cooled to 100 ℃, BHT
0.3 parts, MEHQ 0.3 parts, and PONPGDA3
After adding 00 parts to dissolve the epoxy ester resin,
After cooling to room temperature, an active energy ray-curable flexo ink resin composition was obtained. This is varnish 3. The viscosity of the varnish 3 by the Gardner-type foam viscometer method of JIS K 5400 was 200 Pa · S.

Comparative Example 1 After adding 444.6 parts of isophorone diisocyanate to the reaction vessel and heating to 70 ° C., 232 parts of hydroxyethyl acrylate was added dropwise over 1 hour. One hour after the end of dropping, polypropylene glycol (hydroxyl value 112
mgKOH / g) 1001.8 parts was added and the temperature was raised to 90 ° C., and the isocyanate group content (NCO%) was 0.1%.
It was made to react until it became the following. Next, PONPGDA7
After adding 19 parts and making it melt | dissolve, it cooled to room temperature and obtained the active energy ray hardening type resin composition for flexographic inks for comparison. This is varnish 1 '. JIS of varnish 1 '
The viscosity of K5400 measured by Gardner-type foam viscometer is 9
It was 0 Pa · S.

Test Examples 1 to 3 and Comparative Test Example 1

Using the varnishes 1 to 3 and the varnish 1'obtained, various materials were blended according to the formulation shown in Table 1, and kneaded with a three-roll mill to prepare an active energy ray-curable flexo ink 1 3 to 3 and comparative active energy ray curable flexo ink 1 ′ were prepared.

[0041]

[Table 1] Pigment: Ishihara Sangyo Co., Ltd., CH58-2 DTMPTA (ditrimethylol propane tetraacrylate): Dainippon Ink and Chemicals Incorporated, Lumicur DTA-400 PONPGDA (PO modified neopentyl glycol diacrylate): Sann Nopco Ltd., Photomer Four
127 Curing agent: Esacure KTO4 manufactured by Lamberty
6

Active energy ray curable flexo ink 1
The kneading properties of 3 to 1 and 1'are all good, and JI
Viscosity of SK 5400 by rotational viscometer method (60 rm
p) was 0.07 Pa · S to 0.15 Pa · S.

Active energy ray curable flexo ink 1
3 to 3 and the comparative active energy ray-curable flexographic ink 1 ′ were used to print on a flexographic printing machine and irradiated with ultraviolet rays to prepare printed matters 1 to 3 and comparative comparative printed matter 1 ′. The printing conditions at this time are as follows. Printing paper: Art paper Printing conditions: 3000 rpm UV lamp: Air-cooled 160 W / cm, high pressure mercury lamp

The printed materials 1 to 3 and the comparative printed material 1 '(evaluation of transferability, adhesion, gloss, and curability) were evaluated as follows. The results are shown in Table 2.

<Evaluation of Transferability> The printed surface was observed with an optical microscope at a magnification of 250 times and evaluated by the number of pinholes due to defective transfer of ink. Good when there are 10 or less pinholes in the field of view. Slightly good when there are 11 to 20 pinholes. The case where 21 or more pieces were observed was regarded as defective.

<Evaluation of Adhesion> Ten-level evaluation was performed according to the X-cut tape method of JIS K5400.

<Evaluation of Gloss> According to JIS K 5400, specular gloss (incident angle 60 °, light reception angle 60 °) was measured.

<Evaluation of Curability> The surface of the printed matter cured by changing the conveyor speed of the ultraviolet irradiation device has a width of 15 m.
Rubbing with art paper of m, 30 mm in length, good when there is no scratch on the surface even when the conveyor speed is 50 m / s or more, good when scratches are found on the surface when the conveyor speed is 40 m / s or more and less than 50 m / s Slightly good, and a case where a scratch was observed on the surface even when the conveyor speed was less than 40 m / s was regarded as poor.

[0049]

[Table 2]

[0050]

The flexographic ink obtained by using the active energy ray-curable resin composition for flexographic ink of the present invention exhibits excellent transferability, and therefore, a pinhole is generated due to poor transferability of the ink. It is difficult and high-speed continuous printing becomes possible. In addition, the adhesion, gloss and curability are improved, and high quality printed matter can be obtained.

Claims (8)

[Claims] 1. An epoxy ester resin (A) obtained by reacting an epoxy resin having an epoxy equivalent of 700 g / eq or less with a monocarboxylic acid as an essential component is converted into a bifunctional or higher functional (meth) acrylate (B). A resin composition for an active energy ray-curable flexo ink, which is characterized by being dissolved. 2. The active energy ray curable flexo ink resin composition according to claim 1, wherein the epoxy resin is a bisphenol A type epoxy resin. 3. The monocarboxylic acid has 4 to 25 carbon atoms.
3. The active energy ray-curable flexo ink resin composition according to claim 2, which is the monocarboxylic acid. 4. The active energy ray curable flexo ink resin composition according to claim 2, wherein the monocarboxylic acid is a hydrogenated rosin. 5. The active energy ray-curable flexo ink resin composition according to claim 2, wherein the epoxy ester resin (A) is an epoxy ester resin modified with a secondary amine and / or a polycarboxylic acid. 6. A bifunctional or higher functional (meth) acrylate (B) is a bifunctional to hexafunctional (meth) acrylate.
The active energy ray-curable flexo ink resin composition according to claim 2. 7. A weight ratio (A / B) of the epoxy ester resin (A) and the bifunctional or higher functional (meth) acrylate (B).
Is 80 / 20-40 / 60, The active-energy-ray-curable flexo ink resin composition according to any one of claims 1 to 6. 8. The viscosity of a Gardner-type foam viscometer is 20 to 20.
The active energy ray-curable flexo ink resin composition according to claim 1, which has a viscosity of 500 Pa · S.