JPH11116875A - Ionizing radiation-curable ink and printed matter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject ink that has sufficient receptivity in no need of long-time heating on its coating by admixing a liquid, water-soluble monomer and a water-absorbing polymer powder thereto. SOLUTION: This ink contains (A) 100 pts.wt. of a liquid and water soluble monomer and (B) 60-120 pts.wt., per 100 pts.wt. of the component A, of a powder of water-absorbing polymer. As a component A, is used a monomer that is polymerizable with radiation and compatible with water usually at room temperature at any ratio, for example, a (meth)acrylic ester of a polyhydric alcohol. The component B is a powder of a cross linked polyacrylic acid salt or of polyisobutylene preferably with an average particle size of 2-20 μm. In the case where ultraviolet rays or visible rays are used as the irradiation, the formulation of a photo-polymerization initiator is recommended thereto in an amount of 2-5 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ionizing radiation curable ink and a printed material using the same.

[0002]

2. Description of the Related Art Conventionally, when ink-jet printing or the like is performed on a base material such as paper, film, or board, a receiving layer is coated on the base material in order to accelerate ink absorption and reduce bleeding. I have. As a coating agent for forming a receiving layer, a water-soluble polymer is dissolved in an aqueous medium.
What added alumina, aluminum hydroxide, etc. as a filler is used.

As another alternative, there has been proposed an ink or the like which is obtained by adding a water-adsorbable organic or inorganic filler to a liquid water-soluble monomer and curing the same.

[0004]

However, the above-mentioned coating agent using an aqueous medium requires a long heating time for coating. Further, the curable ink obtained by adding a filler to the above-mentioned liquid aqueous monomer was not sufficient in terms of acceptability. Accordingly, an object of the present invention is to provide an ionizing radiation-curable ink having sufficient receptivity without requiring long-time heating for coating.

[0005]

The present invention provides an ionizing radiation-curable ink comprising a liquid water-soluble monomer and a water-absorbing polymer powder.

In the present invention, the liquid water-soluble monomer is a radiation-polymerizable monomer which can be dissolved in water at an arbitrary ratio at normal temperature. Examples include (meth) acrylates of polyhydric alcohols, (meth) acrylates of N-alkylamino alcohols,
Polyethylene glycol (meth) acrylate,
Examples thereof include N-alkyl (meth) acrylamide, vinyl ether of polyhydric alcohol, and the like.

More specific examples include butanediol monoacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, N, N-
Examples thereof include diethylaminoethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-dimethylacrylamide, acryloylmorpholine, and 2-hydroxyethyl vinyl ether. It is also possible to use mixtures of these monomers.

Further, 80 parts by weight or less of a water-insoluble monomer may be mixed with 100 parts by weight of these water-soluble monomers. Further, a polymerizable oligomer can be used in combination.

Examples of the water-insoluble monomer include phenoxyethyl acrylate, isobornyl acrylate, hexanediol acrylate and the like.

Next, the water-absorbing polymer powder which is an essential component of the present invention will be described. The water-absorbing polymer powder in the present invention is a resin powder in which a water-soluble polymer having a large number of hydrophilic groups in a molecular structure is crosslinked and made insoluble in water and other solvents. Examples of such powders include crosslinked polyacrylate, isobutylene, maleic acid copolymer, starch, crosslinked acrylate graft polymer, crosslinked polyvinyl alcohol, and crosslinked polyethyleneimine. .

More specifically, the following product powders can be exemplified. That is, Arasorp (Arakawa Chemical), Poise SA (Kao), KI Gel (Kuraray), Sunwet (Sanyo Chemical), Sumikagel (Sumitomo Chemical), Ariakeep (Sumitomo Seika), Alonzap (Toa Gosei Chemical) , Aqua Reserve (Nippon Synthetic Chemical Industry), Aquaric (Nippon Shokubai), Diamond Wet (Mitsubishi Chemical), AR
IDAL (Chemdal USA), DRYTECH
(Dow Chemical USA), WATERLO
CK (Grain Processing USA), S
Powders such as ANWET (Hoechst Celanese USA), AQUALIC (NA Industry USA), LUQUASORB (BASF Germany).

The average particle size of the water-absorbing polymer powder is generally preferably about 0.5 to 35 μm. More preferably, it is about 2 to 20 μm. If the particle size is less than 0.5 μm or more than 35 μm, the printing characteristics of the ink will be lost,
Alternatively, the acceptability of the printed matter may be poor.

The radiation-curable ink of the present invention comprises a liquid water-soluble monomer and a water-absorbing polymer powder. Preferably, the amount of the water-absorbing polymer powder is 100 parts by weight of the liquid water-soluble monomer. , 1 to 300 parts by weight. More preferably, the amount of the water-absorbing polymer powder is 30 to 100 parts by weight of the liquid water-soluble monomer.
150 parts by weight are used, more preferably 60 to 120 parts by weight. If the amount of the water-absorbing polymer powder exceeds 300 parts by weight, the printing characteristics of the ink may be reduced,
If the amount is less than 1 part by weight, the receiving performance may be reduced.

In the present invention, powders such as silica, alumina, aluminum hydroxide, protein, and pulp may be used in combination as a filler other than the water-absorbing polymer powder, if necessary.

Examples of other additives include oligomers such as oligoester acrylates, oligomers of acrylic acid esters having a polymerizable double bond, and oligourethane acrylates. Further, a monomer-soluble polymer can be used.

Examples of more detailed oligomers are shown in Kiyomi Kato, "Ultraviolet Curing System", published by Sogo Gijutsu Center (published February 28, 1989), pp. 149-333.

Examples of the polymer include (meth) acrylate (co) polymer, vinyl chloride vinyl acetate copolymer,
Examples include polyester, cellulose acetate, butyrate, and butyral resin.

In the present invention, α-rays, γ-rays, X-rays, ultraviolet rays, visible rays and the like can be used as the ionizing radiation for promoting the polymerization of the monomer.

When ultraviolet rays or visible rays are used as the radiation, a photopolymerization initiator for initiating polymerization is used in combination.

Accordingly, the ionizing radiation-curable ink according to another aspect of the present invention includes an ink containing a photopolymerization initiator for initiating polymerization of monomers.

Examples of the photopolymerization initiator are not particularly limited as long as radicals or other active species generated by light react with the polymerizable double bond in the above-mentioned monomer or oligomer. Examples include benzoin ethyl ether, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2
-Methyl-1- (4- (methylthio) phenyl) -2-
Morpholinopropanone-1, bisacylphosphine oxide and the like can be mentioned. These photopolymerization initiators can be used alone or in combination of two or more.

Further examples of photopolymerization initiators include those disclosed in Kiyomi Kato, "Ultraviolet Curing System", published by Sogo Gijutsu Center (published February 28, 1989), pp. 65-148. Examples thereof include a polymerization initiator. The use amount of these photopolymerization initiators is not particularly limited, but is generally about 1 to 10% by weight, preferably 2 to 5% by weight.
It is used in the order of% by weight.

Further, the ink of the present invention may contain a leveling agent, an antifoaming agent, a dye, a pigment and the like, if necessary.

The ink of the present invention can be generally printed by any printing method such as gravure printing, flexographic printing and screen printing. However, in order to give the printing layer sufficient receiving performance, the thickness of the printing layer is preferably from 5 to 5. It is desirable that the thickness be about 100 μm, more preferably about 10 to 40 μm.

Therefore, the most preferable example is screen printing in which the thickness of the printing layer is easily adjusted to the above range. Further, the ink of the present invention can be used after being coated by a coating method.

In any case, the ink of the present invention is cured by irradiation with ionizing radiation or light acting on a photopolymerization initiator after printing or coating to give a printed layer.

The printing layer thus obtained is rich in receptivity and provides a preferable receiving layer. In addition, this receiving layer can be easily formed not only on paper but also on a base material such as a plastic film, a plastic plate, or a metal plate.

When ink-jet printing or the like is performed on the receiving layer, the printed ink is quickly received and absorbed by the receiving layer, so that ink-jet printing can be performed almost without blurring.

In particular, if the ink of the present invention is used and a receiving layer is provided on the back surface of a compact disc as an optical information medium, the use and characteristics of the compact disc can be easily determined by aqueous ink jet printing or the like. It is extremely useful because it can be recorded.

[0030]

EXAMPLES Hereinafter, the present invention will be described by way of examples. The performance of the receiving layer printed on the substrate was determined by the sharpness of an image when ink-jet printing was performed on the receiving layer.

Examples 1 to 4 and Comparative Examples 1 to 3 Various raw materials were blended in a weight ratio shown in Table 1 below, and these were dispersed using a stirrer to prepare an ultraviolet curable ink.

[0032]

[Table 1] The ink thus adjusted was screen-printed on the back surface of a polycarbonate compact disk using a 300-mesh screen, and then irradiated with ultraviolet rays to form a receiving layer.

Next, using an ink jet printer,
Printing on the receiving layer with water-based color ink, image clarity (comprehensive evaluation of good coloring and less bleeding)
Was evaluated. The results are shown in Table 2. The evaluation in Table 2 is ◎: very good, ○: good, Δ: slightly poor, ×:
Indicates failure.

[0034]

[Table 2]

As described above, the ionizing radiation-curable ink of the present invention enables printing not only on the entire surface of the substrate but also on only the necessary portions, and quickly without the step of evaporating water. Printing can be completed. Then, the obtained printing layer becomes rich in receptivity, and thus a printed material having a preferable receiving layer can be provided. Also, if the substrate is a compact disc,
Further, it is possible to easily record the use, characteristics, and the like of the compact disc by aqueous inkjet printing or the like.

[0035]

Claims (8)

[Claims] 1. An ionizing radiation-curable ink comprising a liquid water-soluble monomer and a water-absorbing polymer powder. 2. The water-absorbing polymer powder has an average particle size of 0.5.
2. The ionizing radiation-curable ink according to claim 1, wherein the thickness is in the range of from 35 to 35 [mu] m. 3. The water-absorbing polymer is a crosslinked product of a partial soda salt of polyacrylic acid.
The ionizing radiation-curable ink according to the above. 4. The ionizing radiation-curable ink according to claim 1, further comprising a monomer-soluble oligomer and / or polymer. 5. The ionizing radiation-curable ink according to claim 1, further comprising a water-adsorbing organic or inorganic filler. 6. The ionizing radiation-curable ink according to claim 1, further comprising a photopolymerization initiator. 7. A printed matter obtained by printing on a synthetic resin substrate with the ink according to any one of claims 1 to 6. 8. The printed matter according to claim 7, wherein the synthetic resin substrate is a compact desk.