JPH08892B2 - Ink having UV curing and oxidative polymerization functions, and printed matter using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high-speed surface-drying (setting) ink that can be used for various kinds of printing such as intaglio printing and screen printing with a thick film layer.

[Conventional technology]

With the increase in printing speed, inks that are cured and dried in a short time by ultraviolet irradiation are becoming popular. But,
In the case of an ink in which a pigment, which is an essential component of the ink, is dispersed, the thickness of the ink film that can be cured even if a good photopolymerization initiator or sensitizer is used is limited to about 10 μm. This is because ultraviolet rays do not penetrate to the inside of the ink film in the ink in which the pigment is dispersed. Therefore, UV drying is widely used in offset printing, etc., where the ink film thickness is at most about 4 μm, but in case of screen printing where the ink film thickness exceeds 10 several μm or intaglio printing where the ink film thickness is several 10 μm or more, these No fast drying system is used. In order to solve these problems, many methods of dispersing a special pigment in the ultraviolet curable composition or adding a special polymerization accelerator or sensitizer, for example, Japanese Patent Publication No.
No. 47889, No. 49-47899, No. 52-32989, JP-A-48
Methods such as -28037, 48-47534, and 115128 have been proposed. However, none of these methods has been sufficiently successful because of limitations such as pigments that can be used and poor ink suitability.

On the other hand, using a UV curable component and an oxidatively polymerizable component together,
Methods for improving pigment dispersibility, adhering to a substrate (printing material), and improving adhesiveness have also been proposed. For example, synthesizing a photopolymerizable substance containing a higher fatty acid (oxidatively polymerizable component) in the molecule is disclosed in JP-A-49-97788 and 51-16107.
No. 50-95006 and many others have been proposed, and those in which an alkyd resin (oxidative polymerization component) is mixed with a photopolymerization substance have been proposed in JP-A-54-25941. However, since all of these proposals are intended only to improve the pigment dispersibility, the adhesion to the substrate, and the adhesiveness, as in the present invention,
The primary purpose of the method is to cure the surface layer of the film instantaneously by UV irradiation, enable stacking and secondary processing immediately after printing or coating, and then naturally dry the inside of the film by oxidative polymerization. different.

[Problems to be Solved by the Invention]

In conventional UV curing (drying) of ink, the printed ink cures and dries at high speed, and the cured film has excellent chemical resistance, abrasion resistance, and robustness. On the other hand, there are drawbacks such as a thin film of curable ink and poor ink suitability such as pigment dispersibility, printability, adhesion to a substrate, and adhesiveness. On the other hand, in oxidative polymerization drying, on the contrary, pigment dispersibility, printability, adhesion to a substrate, ink such as adhesiveness, excellent paint suitability, on the other hand, the drying speed is slow, the chemical resistance of the cured film, Abrasion resistance,
There are drawbacks such as poor durability such as robustness.

An object of the present invention is to obtain an ink for combined UV-curing and oxidative-polymerization, which makes use of the advantages of both UV-curing (drying) and oxidative-polymerization drying, and which complements each other's drawbacks. That is, it has high-speed drying property by ultraviolet irradiation, and the uncured part of the inner layer of the film that cannot be dried by ultraviolet drying is cured and dried by oxidative polymerization, and further pigment dispersibility, printability, adhesion to substrate, adhesiveness It is intended to obtain an ink having excellent ink suitability and the like, and a cured film having excellent chemical resistance, abrasion resistance, and fastness.

[Means for solving the problem]

In order to achieve the above object, in the ink of the present invention, by using a mixture of an ultraviolet curable composition and an oxidative polymerization composition, an ink that can be used in combination with ultraviolet curing (drying) and oxidative polymerization drying. It is the one. That is, this ultraviolet curing and oxidative polymerization combined use ink instantaneously cures the surface layer of the film by irradiation with ultraviolet light, and enables stacking and secondary processing immediately after printing or coating, and thereafter the inside of the film can be naturally dried by oxidative polymerization. And pigment dispersibility,
It is characterized by excellent printability, ink suitability such as adhesion to substrates, adhesiveness, etc., and resistance of the cured film such as chemical resistance, abrasion resistance and fastness. Normally, oxygen is used as a polymerization inhibitor to prevent gelation of UV-curable components such as acrylates, but in the present invention, it is used as a polymerization initiator by combining an oxidative polymerization component such as an alkyd resin with oxygen. There is.

In the above UV curable and oxidative polymerization combined ink, the UV curable composition is a mixture of a photocurable resin compound and a photopolymerization initiator or a sensitizer, and the oxidative polymerizable composition is an oxidative polymerizable substance and an oxidant. A mixture of polymerization catalysts is used. These components, that is, the photocurable resin compound, the photopolymerization initiator, the sensitizer, the oxidative polymerizable substance, the oxidative polymerization catalyst,
Generally known materials used for ultraviolet curing (drying) and oxidative polymerization drying type inks can be used. For example, the photocurable resin compound is a monomer or prepolymer of various 1 to 6 functional acrylates and methacrylates, and the photopolymerization initiator is a cleavage type benzoin, benzoin ether, etc., a hydrogen abstraction type benzyl, benzophenone, etc. Ion-reactive allyldiazonium salts and the like, and sensitizers include tertiary amines and the like. The oxidatively polymerizable substance is a linseed oil, a drying oil such as soybean oil or a semi-drying oil, or a drying oil-modified resin varnish such as an alkyd resin varnish, and the oxidative polymerization catalyst is cobalt, manganese, lead, iron. And other metal compounds such as cobalt borate, cobalt octylate, cobalt naphthenate, and lead monoxide.

In order to improve the storage stability and the on-machine stability of the ink, it is effective to add a polymerization inhibitor (inhibitor) capable of controlling only the oxidative polymerization rate without impairing the ultraviolet curability. As a polymerization inhibitor (suppressor) that can suppress only the oxidative polymerization rate without adversely affecting the ultraviolet curability, that is, the curability of the ultraviolet curable component by the irradiation of ultraviolet rays, it is commonly used in ultraviolet curing, and known polymerization inhibitors (Suppression)
Agents such as p-methoxyphenol and hydroquinone can be used.

The pigment that can be used in the above-mentioned UV-curable and oxidative polymerization combined ink is not limited at all in terms of various properties such as optical transparency, hiding property, reflectivity, and luminescent property. Can be used.

[Action]

As described above, the intaglio printed matter and the screen printed matter using the ink in which various pigments are dispersed in the mixture of the ultraviolet curable composition and the oxidatively polymerizable composition, the film surface layer portion is instantly cured and dried by the ultraviolet irradiation. . Therefore, even if the printed matter is piled up immediately after printing, no offset or blocking occurs, and the secondary processing becomes possible. Then, the uncured layer inside the coating on the printed or coated material which is stacked or processed secondarily is naturally dried by oxidative polymerization.
In this oxidative polymerization, the oxidatively polymerized component is oxidatively polymerized, and the active species such as radicals generated in the process also induce a polymerization reaction of acrylate or the like which is an ultraviolet ray curable component to complete the curing and drying of the entire film.

That is, the oxidative polymerization component itself acts as a polymerization initiator, and the unreacted UV-curable composition promotes oxidative polymerization. For that purpose, the oxidative polymerization component needs to be limited and must be a substance that gradually generates radicals at room temperature, such as a semi-drying oil or a drying oil-modified alkyd resin.

In this case, it has been confirmed that the oxidative reaction rate of the UV-curable component is faster than the oxidative polymerization rate of the oxidative-polymerizable components, and thus the proportion of the UV-curable component in the resin component can be increased. By doing so, the cured film has excellent resistance such as chemical resistance, abrasion resistance, and robustness. In addition, the inner layer of the coating that is in contact with the base material does not instantly cure even when irradiated with ultraviolet rays, so that it is well compatible with the base material, and the internal stress associated with the cure is sufficiently relaxed to prevent distortion. Such factors are also one of the factors that improve the adhesion and adhesiveness of the cured film to the substrate.

As described above, since it can be copolymerized by active species such as radicals generated in the oxidative polymerization process, a polymerization inhibitor (suppressor) for suppressing the oxidative polymerization rate can be added as necessary without delaying the ultraviolet curing rate. It is desirable to add.

Although it is clear from the above-mentioned curing principle, the pigment to be used is not limited as described above, and any pigment can be used.

〔Example〕

Based on the formulation examples shown in Tables 1 and 2, various materials were blended,
Kneading was carried out by a conventional method using a three-roll mill to prepare an ultraviolet curing, oxidation polymerization combined use type intaglio ink and screen ink.

The UV-curable and oxidative polymerization combined type intaglio ink was continuously printed by an ordinary method using an intaglio printing machine. The printed matter to be continuously printed was conveyed in the ultraviolet irradiation device immediately after printing, and then stacked as it was on the paper discharge section. The printing conditions and ultraviolet irradiation conditions at this time are as follows. Printing paper: Securities paper, printing plate surface depth: 130 μm, printing speed: 25 m / m
in, UV irradiation transfer speed: 25m / min, UV lamp: air-cooled, 120w / cm, 2 metal halide lamps, number of discharged sheets stack: 5000 sheets.

The ultraviolet curing and oxidative polymerization combined type screen ink was printed by a usual method using a screen printing machine. Immediately after printing, the printed matter was irradiated with ultraviolet rays and then quickly bent by 90 °. The printing conditions and ultraviolet irradiation conditions at this time are as follows. Printing paper: Special art paper, Screen line number: 133 lines, Printing speed: 25m / min, UV irradiation transfer speed: 25m / min, UV lamp: Air-cooled, 120w / cm, 2 metal halide lamps.

The results of the above printing were as follows.

The UV-curable and oxidative polymerization combined type intaglio ink and screen ink showed printability equivalent to that of the conventional intaglio ink (oxidation polymerization type) and screen ink (solvent evaporation type).

In continuous intaglio printing of UV curable and oxidative polymerization type intaglio ink, there is no set-off and blocking even when 5,000 sheets of printed matter are piled up at the discharge section, and screen printing of UV curable and oxidative polymerization type screen ink Even in the 90 ° bending process immediately after that, there were no problems such as cracks, cracks, and peeling of the cured film.

UV-curing, oxidation polymerization combined type intaglio ink and screen ink printed matter are extremely superior in chemical resistance and abrasion resistance compared to conventional intaglio ink (oxidation polymerization type) and screen ink (solvent evaporation type) printed matter. In addition, the adhesion to the substrate was as good as that of conventional inks (oxidation polymerization type and solvent evaporation type).

The on-press stability of the UV-curable and oxidative polymerization combined type intaglio ink and screen ink was good.

The kneading properties at the time of preparation of ultraviolet curing, oxidation polymerization combined type intaglio ink and screen ink were the same as those of conventional intaglio ink (oxidation polymerization type) and screen ink (solvent evaporation type).

〔The invention's effect〕

The ultraviolet curing and oxidative polymerization combined ink of the present invention has the functions as described above, and therefore exhibits the effects described below.

The ultraviolet curable and oxidative polymerization combined ink of the present invention, by mixing an appropriate amount of the ultraviolet curable composition and the oxidative polymerization composition, exerts the advantages of both and acts to complement each other's defects. That is, an intaglio printed matter using an ink in which various pigments are dispersed in a mixture of an ultraviolet curable composition and an oxidatively polymerizable composition, a screen printed matter, the surface layer of the film is instantaneously cured and dried by irradiation with ultraviolet rays. Alternatively, even if printed materials are piled up immediately after coating, set-off and blocking can be prevented, and secondary processing becomes possible. Then, the uncured layer inside the film on the stacked or secondary processed print is naturally dried by oxidative polymerization, so that the curing and drying of the entire film is completed during the subsequent storage. Furthermore,
The pigment dispersibility of the ink, printability, adhesion of the cured film to the substrate, adhesion, etc. are as excellent as those of the oxidatively polymerizable composition,
Further, the resistance of the cured film such as chemical resistance, abrasion resistance and fastness is as excellent as that of the ultraviolet curable composition.

By adding a polymerization inhibitor (inhibitor) to the UV curing and oxidative polymerization combined ink, if necessary, it is possible to improve the on-machine stability and storage stability of the ink and paint without impairing the UV curability. .

There is no limitation on the pigment that can be used in the ultraviolet curing and oxidative polymerization combined type ink, and thus any type of pigment can be used.

Claims (5)

[Claims] 1. An ultraviolet-curable composition characterized in that the surface layer of a film is instantly cured by irradiation of ultraviolet rays to enable stacking and secondary processing immediately after printing, and then the inside of the film is naturally dried by oxidative polymerization. A UV-curable, oxidative polymerization combined ink in which various pigments are kneaded in a mixture of a pigment and an oxidatively polymerizable composition. 2. A mixture of a photocurable resin compound and a photopolymerization initiator or a sensitizer is used as the ultraviolet curable composition, and a mixture of an oxidative polymerizable substance and an oxidative polymerization catalyst is used as the oxidative polymerizable composition. The ultraviolet curing and oxidative polymerization combined use ink described in 1. 3. The ultraviolet curing and oxidative polymerization combined ink according to claim 1, wherein a polymerization inhibitor (inhibitor) for controlling the oxidative polymerization rate is added to the mixture of the ultraviolet curable composition and the oxidatively polymerizable composition. . 4. The pigment used in the mixture of the UV-curable composition and the oxidatively polymerizable composition is completely limited in various pigment characteristics such as optical transparency, hiding property, reflectivity and luminescent property. The ultraviolet curing and oxidative polymerization combined ink according to claim 1, wherein the ink is absent. 5. An ultraviolet-curable composition, characterized in that the surface layer of the film is instantly cured by irradiation of ultraviolet rays to enable stacking and secondary processing immediately after printing, and then the inside of the film is naturally dried by oxidative polymerization. A printed material using an ink composition for ultraviolet curing and oxidative polymerization, which is obtained by kneading various pigments into a mixture of a pigment and an oxidatively polymerizable composition.