JP2000302997A - Activating-energy radiation curing composition and formation of cured film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an activating-energy radiation curing composition having excellent hardenability and also capable of forming cured membrane excellent in gloss, and to provide a method for forming cured membrane using the same composition. SOLUTION: This composition comprises azo pigment processed with rosin and a compound having at least one ethylenic unsaturated double bond, and the quantity of rosin in the pigment is 0.05-1.0 wt.% based on the weight of the composition. This method for forming cured membrane is to subject the composition to activating-energy radiation.

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 composition which is easily cured by low energy active energy rays and is excellent in productivity, and to a method for forming a cured film using the same. It is.

[0002]

2. Description of the Related Art Active energy ray curing techniques such as electron beam and ultraviolet ray (1) are quick-curing and have high productivity.
It has the advantages of (2) low energy cost and (3) reduction of the emission of volatile components to the environment by eliminating the use of solvents, and is widely used in applications such as paints, inks and adhesives. Pigments are blended in inks and paints for the purpose of coloring, and a typical example of a printing ink uses a plurality of inks with different pigments blended for color reproduction. Generally, color reproduction is performed using four-color process inks of yellow, red and blue inks, and pigments matching the hue are used for the inks of each color.

[0003] Among the active energy ray-curable inks made for the above purpose, the ultraviolet curable ink has a difference in curability depending on the hue.
It is known that black ink has poor curability compared to red. On the other hand, electron beams have high transparency,
It has been said that the curability of an electron beam curable ink is hardly affected by hue. However, in reality, there has been observed a phenomenon in which the curability is affected by factors other than the hue. In particular, in the case of electron beam-curable inks and paints, a phenomenon in which curing is poor when an azo pigment is contained is observed. Had been. As a result, the curing of a particular color is poor,
In color-matched process printing, there has been a problem that high-speed processing, which is a characteristic of electron beam curing, cannot be performed.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an active energy ray-curable composition capable of forming a cured film having good curability and excellent gloss, and good curability. Another object of the present invention is to provide a method for forming a cured film having excellent gloss.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that a composition containing a pigment using rosin as a surface treatment agent can be cured in a radical polymerization system using active energy rays. The present invention has found that by controlling the amount of rosin in the composition to a specific range, the curability of the composition becomes good and a cured film having excellent gloss and color developability can be obtained. Was completed.

That is, the present invention relates to a composition containing a rosin-treated azo pigment and a compound having an ethylenically unsaturated double bond, wherein the rosin content in the rosin-treated azo pigment is 0.1% based on the composition. The present invention relates to an active energy ray-curable composition which is from 0.5 to 1.0% by weight. The present invention also relates to a method for forming a cured film by irradiating the composition with an active energy ray.

The active energy ray-curable composition of the present invention contains a rosin-treated azo pigment and a compound having an ethylenically unsaturated double bond. Rosin-treated azo pigments
(1) Fine and high transparency due to the effect of preventing the crystal growth of the pigment, (2) Soft and good dispersibility due to prevention of dry aggregation of the pigment particles, and (3) Oily varnish because the pigment surface is lipophilic. Have good wettability.

When the azo pigment is treated with rosin, after completion of the coupling reaction between the diazotized amine and the coupler component, aqueous solutions of various rosin sodium salts are added to the reaction solution, and calcium chloride or calcium chloride is added. Barium chloride is added to form an insoluble rosin salt, and the pigment surface is coated. Rosin may be acidified with a mineral acid or the like to cover the surface of the pigment without being converted into a metal salt. However, an azo pigment treated with a rosin that is not a metal salt, so-called metal-free rosin, has poorer curability. Rosin is a natural resin called rosin and has abietic acid as a main component. As the rosin, gum rosin, polymerized rosin, disproportionated rosin, hydrogenated rosin, maleated rosin, fumarated rosin, wood rosin and the like can be used. The amount of rosin in the rosin-treated azo pigment is usually in the range of 0.5 to 20% by weight based on the rosin-treated azo pigment.

The amount of rosin in the rosin-treated azo pigment is as follows:
It is 0.05 to 1.0% by weight, preferably 0.1 to 0.5% by weight, based on the composition. When the amount of rosin contained in the composition is less than 0.05% by weight, problems such as poor pigment dispersibility, poor fluidity of the composition, and poor gloss and color development of the cured film occur. . On the other hand, if the rosin content exceeds 1.0% by weight, the curability by active energy rays, especially electron beams, is remarkably reduced.

It is presumed that the suppression of the curing of the composition by rosin is due to the radical scavenging effect by the structure of abietic acid as the main component in rosin. The remarkable tendency in the case of electron beam curing is due to the difference between the ultraviolet rays and the electron beam of the generated radical species and the effect of absorption of the electron beam by the conjugated double bond of abietic acid. It is estimated that there is.

The amount of rosin in the composition can be measured, for example, as follows. 10 g of the composition is dissolved in a mixed solvent of methyl ethyl ketone / toluene (weight ratio: 1: 1), centrifuged at 16,000 rpm for 30 minutes, and the obtained supernatant is collected. The same operation is repeated three times for the precipitate. All supernatants are collected, concentrated with a rotary evaporator while shielding light, and acetone is added to make an acetone solution. Methanol is added dropwise to the acetone solution, the resulting precipitate is filtered, hexane is added dropwise to the supernatant, and the resulting precipitate is recovered and weighed after air drying. An infrared spectroscopy spectrum of the collected precipitate is measured to identify that it is rosin. When the recovered precipitate contains substances other than rosin, the rosin content can be determined by calculating the abundance ratio using infrared spectroscopy, gas chromatogram, or the like.

As the compound having an ethylenically unsaturated double bond, various oligomers and monomers can be used. The oligomer refers to a low polymer having a molecular weight of several hundreds to several thousands, and is generally a liquid or a solid having a very high viscosity. Examples of the oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate. Monofunctional or polyfunctional (meth) acrylates can be used as the monomer.

The monofunctional (meth) acrylates include:
Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth)
Acrylate, polyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate methyl ether, phenylethyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate , Methoxytripropylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, dimethylaminoethyl (meth) acrylate,
(Meth) acryloylmorpholine, isobornyl (meth) acrylate, (meth) acrylamide and the like can be mentioned.

The polyfunctional (meth) acrylates include
Butanediol di (meth) acrylate, hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, nonanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol Di (meth) acrylate, trisacryloyloxyethyl isocyanurate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, epoxy adipate (meth) acrylate, hydrogenated bisphenol Ethylene oxide di (meth) acrylate, glycerin ethylene oxide added tri (meth) acrylate, trimethylolpropane Tri (meth) acrylate, triethylolpropane tri (meth) acrylate, ethylene oxide-added trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ethylene oxide-added pentaerythritol tri ( (Meth) acrylate, propylene oxide-added pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, and the like.

The active energy ray-curable composition of the present invention can contain an inert resin having no reactivity as appropriate according to the physical properties of the film. As the inert resin, for example, diallyl phthalate resin (for example, Daiso Dap A manufactured by Osaka Soda Co., Ltd.), petroleum resin (for example, Mitsui Petrochemical Co., Ltd .: Hiretsu, Arakawa Chemical Co., Ltd .: Alcon), cyclic ketone resin (for example, Honshu Chemical Co., Ltd .: Halon 80); formaldehyde resin (for example, Mitsubishi Gas Chemical Co., Ltd .: Nicanol); acrylic resin (for example, Arakawa Chemical Co., Ltd .: Beam Set 255). Various pigment dispersants, additives, stabilizers, and the like can be added to the active energy ray-curable composition of the present invention as needed.

The active energy ray-curable composition of the present invention is used as a printing ink, a paint, a resist material and the like. Examples of the printing ink include offset ink, letterpress ink, flexographic ink, gravure ink, silk screen ink, and the like. Examples of the paint include a top coat for flooring, a paint for woodwork, a paint for cans, and the like.
The active energy ray-curable composition of the present invention can be applied to various types of paper, plastic films, metal plates, and other base materials according to a standard method, and then irradiated with active energy rays to form a cured film. Examples of active energy rays include electron beams and ultraviolet rays, but since electron beam irradiation does not apply heat to the substrate, it is possible to form a cured film on a film substrate that is weak to heat. It is preferable to form a cured film by irradiating an electron beam from the viewpoint of not using the film.

Examples of the electron beam irradiation apparatus include a curtain beam type, an area beam type, a broad beam type, a scanning beam type, and a vacuum tube type. The electron beam is preferably a low energy beam type having an acceleration voltage of 30 to 300 KV, and it is particularly preferable to irradiate an electron beam of 30 to 100 KV in consideration of the influence of deterioration of the substrate due to the electron beam. The irradiation dose of the electron beam is 5 to 20.
About 0 KGy is preferable, and 3 to 20 KGy is particularly preferable. Examples of the ultraviolet irradiation device include a high-pressure / low-pressure mercury type, a metal halide type, and an ultraviolet laser type (excimer) device.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
In the examples, “parts” and “%” mean “parts by weight” and “% by weight”, respectively. [Preparation of varnish] To 59.9 parts of trimethylolpropane triacrylate, 0.1 part of hydroquinone and diallyl phthalate resin ("DT150" manufactured by Toto Kasei Co., Ltd.) 4
0 part was melted at 100 ° C. or lower to prepare Varnish A. Also, to 60.0 parts of trimethylolpropane triacrylate,
A varnish B was prepared by dissolving 0.1 part of hydroquinone and 40 parts of epoxy acrylate (“Loxy SP-1509” manufactured by Showa Polymer Co., Ltd.) at 100 ° C. or lower.

[Rosin-treated azo pigment (CI Pigm)
ent Red 57: 1)] According to a usual method, 18.7 parts of 1-amino-4-methylbenzene-2-sulfonic acid was stirred with 400 parts of water and 4 parts of sodium hydroxide at room temperature for 30 minutes, Completely dissolved. After adding 25 parts of 35% hydrochloric acid and acidifying the mixture, 200 parts of ice was added and the mixture was cooled to 0 ° C to 3 ° C. Next, 7 parts of sodium nitrite dissolved in 25 parts of water was added, and stirring was continued at 5 ° C. or lower for 30 minutes to obtain a diazo component. On the other hand, 19 parts of β-oxynaphthoic acid were stirred at 40 ° C. for 20 minutes together with 1000 parts of water and 10 parts of sodium hydroxide to completely dissolve,
Upon cooling to ° C., a coupler component was obtained. After the diazo component was added dropwise to the coupler component over 30 minutes, stirring was further continued for 1 hour to complete the coupling reaction. The pH of the coupling solution was 9.5 to 10.0. An aqueous solution of a rosin sodium salt was added to the aqueous slurry thus obtained, and barium chloride was further added to coat the pigment surface as an insoluble rosin metal salt, followed by drying and pulverization, followed by rosin-treated azo pigment A. , B, C, D
I got The amount of rosin in the treated pigment was 10% for pigment A, 5% for pigment B, 1% for pigment C, and 0.5% for pigment D, based on the treated pigment.

(Examples 1 to 5, Comparative Examples 1 and 2) Pigment, varnish and pentaerythritol tetraacrylate (type of pigment used, varnish, and amount of monomer are shown in Table 1.
Described above) and dispersed with a three-roll mill to obtain an electron beam-curable offset printing ink. In Comparative Example 2, an azo pigment not treated with rosin (untreated pigment) was used. The ink obtained by the above procedure was printed on coated paper to a thickness of about 2 μm by an RI tester (a simple printing machine generally used in the printing ink industry). After printing, a cured film was formed by irradiation with an electron beam using an electron beam irradiation device. Irradiation conditions were: acceleration voltage 50 KV, power consumption 10 W,
The conveyor speed was 50 m / min.

[0021]

[Table 1]

The curability of the obtained cured film was evaluated by the following three methods. In addition, the color development of the cured film was visually evaluated on a five-point scale from good to poor. Table 2 shows the results. 1. 1. Drying property by touching finger (evaluated in 5 steps from 5 to 1). Scratch resistance of printed surface by nail (good 5 to 1 poor 5
It was evaluated on a scale. ) 3. MEK rubbing test (a cotton swab was soaked in methyl ethyl ketone, the printed surface was lightly rubbed, and the number of times until the undercoated paper surface was observed was measured.)

[0023]

[Table 2]

(Examples 6-8, Comparative Examples 3-4) Pigment, varnish and pentaerythritol tetraacrylate, initiator (type of pigment used, varnish, monomer,
The amount of the initiator is described in Table 3), and the mixture was dispersed with three rolls to obtain an ultraviolet-curable offset printing ink. The following were mixed and used as the initiator. In addition,
In Comparative Example 4, an azo pigment not subjected to rosin treatment (untreated pigment) was used. Initiator ("Irgacure 907" manufactured by Ciba-Geigy) 40% Initiator ("KAYACURE EPA" manufactured by Nippon Kayaku) 40% Initiator ("KAYACURE DETX" manufactured by Nippon Kayaku) 20%

[0025]

[Table 3]

The obtained ink was printed on coated paper in the same manner as in Example 1, and then irradiated with ultraviolet rays using an ultraviolet irradiation apparatus ("Unicure" manufactured by Ushio Inc.) to form a cured film. The irradiation conditions were a lamp output of 120 W / cm and a conveyor speed of 50 m / min. With respect to the obtained cured film, curability and color development were evaluated in the same manner as in Example 1. Table 4 shows the results.

[0027]

[Table 4]

[0028]

According to the present invention, a cured film having excellent gloss can be formed by low energy active energy rays.

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Claims (4)

[Claims] 1. A composition comprising a rosin-treated azo pigment and a compound having an ethylenically unsaturated double bond, wherein the amount of rosin in the rosin-treated azo pigment is 0.05 to 1. An active energy ray-curable composition which is 0% by weight. 2. A method for forming a cured film, comprising irradiating the composition according to claim 1 with an active energy ray. 3. The method according to claim 2, wherein the active energy ray is an electron beam. 4. The method according to claim 3, wherein the electron beam has an accelerating voltage of 30 to 300 KV.