JP2012140615A - Primer for inkjet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a primer ink to be applied on a recording medium by an inkjet system, which can improve the fixing property of image formed on various non-absorbent recording media with inkjet ink and can attain a high-quality image.SOLUTION: The primer ink includes at least one adhesion promoting component selected from the group consisting of N-vinyl lactam compound, acrylamide-based compound and N-vinylamide compound; and 2-hydroxy-3-phenoxypropyl acrylate. The primer ink has a surface tension of 25-31 mN/m and a viscosity of 50 mPa s or less.

Description

  The present invention relates to a primer, and more particularly to a primer ink for ink jet recording that is coated by an ink jet method.

  An ink jet system that ejects ink in droplets from an ink ejection port is used in many printers because it is small and inexpensive, and can form an image without contact with a recording medium.

  Recently, commercial printing and industrial printing using an ink jet printer have been performed for applications such as advertising, posters, and decoration, as well as home or office photo printing and document printing. Along with this, (1) formed for conventional home or office ink-jet inks and ink-jet recording prints so that they can be used as ink-jet inks and ink-jet ink recording prints suitable for commercial printing and industrial printing. There is a strong demand for high image quality and (2) printing on various recording media including non-absorbing recording media such as plastics.

Conventionally, many of ink-jet inks and recording devices and methods (hereinafter abbreviated as ink-jet inks including inks, devices and methods) used for home or office printing are intended for photographic printing or document printing. Has been developed. For this reason, in the case of recording on a non-absorbable recording medium with a conventional inkjet ink or the like, bleeding tends to occur in the image if it takes time to dry the droplet after droplet ejection or to penetrate into the recording medium. In addition, there is a problem in that mixing occurs between adjacent ink droplets on the recording medium, thereby preventing sharp image formation. Further, when an image is formed on a non-absorbable recording medium, there is a practical problem that the fixing property of the image is not good, for example, the image is easily peeled off from the recording medium and is not easily scratched. In addition, when applied to high-speed printing, the adjacent droplets move together after being ejected, and the droplets move, so they deviate from the landing position, and the line width is uneven when drawing thin lines. Further, when a colored surface is drawn, there is a problem that color unevenness occurs due to droplet ejection interference, such as color unevenness.
Hereinafter, in this specification, characteristics such as scratching and ease of peeling are referred to as “fixability”, and characteristics relating to image quality such as color unevenness and non-uniform line width are referred to as “drawability”.

  As a method for solving the above problem, for example, a technique for improving the components and configuration of the ink itself (for example, Patent Document 1), a technique for improving an ink jet recording apparatus and method (for example, Patent Document 2), and the like. Various techniques have been proposed. However, the technique disclosed in the above document cannot sufficiently solve the problem of the fixability of an image recorded on a non-absorbable recording medium, which is particularly important in commercial or industrial printed matter. It was. On the other hand, Patent Document 3 discloses that a primer is employed in order to solve the problem of fixability, and that the primer is semi-cured as a recording method and is performed in a single pass. It also describes or suggests ink and primer components, their preferred physical properties, and the relationship between them. This is an attempt to solve the fixing problem from a comprehensive viewpoint.

Special table 2003-53223 gazette Japanese Patent Laying-Open No. 2005-096254 JP 2009-083267 A

  However, a primer is formed using a compound described in Patent Document 3 on a non-absorbable recording medium other than PET that is not used in Patent Document 3 (for example, an acrylic sheet), and the primer is formed thereon. The image was peeled off immediately after being rubbed lightly with a nail, and the drawing performance was not evaluated. That is, the fixability and drawing performance of an image formed on a non-absorbable recording medium are still not fully satisfactory.

  Accordingly, an object of the present invention is to improve the fixability of an image formed by inkjet ink on various non-absorbable recording media and to realize a high-quality image. An object of the present invention is to provide a primer ink that is coated on a medium by an inkjet method.

In the case of forming an image using inkjet ink on a non-absorbable recording medium, it is effective to add a primer (undercoat) to improve the fixing property of the image. It has been taken up in many literatures. However, as represented by the above-mentioned Patent Document 3, in the conventional literature, only substances that can be used for the primer are generally described, and the idea that the primer itself is coated by an ink jet method is used. There was no. Further, when the substances constituting the primer are classified functionally, (1) ensuring adhesion with the recording medium, (2) having affinity with the printed image of the image forming ink, and (3) It is necessary to be configured to satisfy all of the requirements that the coating film has curability.
The present inventors have at least one selected from the group consisting of N-vinyl lactam compounds, acrylamide compounds and N-vinylamide compounds when forming images on various non-absorbent recording media with inkjet ink. It has been found that a primer ink containing an adhesion promoting component and 2-hydroxy-3-phenoxypropyl acrylate as a polymerizable compound can improve image fixability and drawing performance, and has led to the present invention. .

That is, the subject of this invention and its preferable aspect are as follows.
[1] A primer ink containing a polymerizable compound and a polymerization initiator, and at least one adhesion promoting component selected from the group consisting of an N-vinyl lactam compound, an acrylamide compound and an N-vinylamide compound, and 2 A primer ink containing hydroxy-3-phenoxypropyl acrylate, having a surface tension of 25 to 31 mN / m and a viscosity of 50 mPa · s or less.
[2] The primer ink according to [1], further including an antigelling agent and a surface conditioner.
[3] The primer ink according to [1] or [2], which is used as a primer for an image forming ink composition having a surface tension of 25 to 32 mN / m 2.

  ADVANTAGE OF THE INVENTION According to this invention, the printed matter formed with the inkjet ink which has favorable fixability with respect to a non-absorbable recording medium and is high-quality can be provided.

Hereinafter, the present invention will be described in detail.
The primer ink of the present invention contains at least one adhesion promoting component selected from the group consisting of N-vinyl lactam compounds, acrylamide compounds and N-vinylamide compounds.
Examples of the N-vinyllactam compound that can be contained in the primer ink of the present invention include N-2-vinylpyrrolidone and N-vinylcaprolactam. Examples of acrylamide compounds include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, Nn-butyl (meth) acrylamide, and Nt. -Butyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) Examples include acrylamide and (meth) acryloylmorpholine. Examples of the N-vinylamide compound include N-vinylformamide and N-vinylacetamide.
In particular, it is preferable to use N-vinylcaprolactam, N-2-vinylpyrrolidone, N, N-dimethyl (meth) acrylamide, acryloylmorpholine, and N-vinylformamide as the adhesion promoting component in the primer ink of the present invention. . These can be used alone or in combination of two or more.
In the present specification, “(meth) acrylamide” means “acrylamide” or “methacrylamide”, and the notations such as “(meth) acrylate” and “(meth) acryloyloxy” described later have the same meaning. Have

  In the primer ink of the present invention, at least one adhesion promoting component selected from the group consisting of an N-vinyl lactam compound, an acrylamide compound and an N-vinylamide compound is preferably 5 masses with respect to 100 mass parts of the primer ink. It is contained in an amount of no less than 60 parts by mass and more preferably no less than 10 parts by mass and no greater than 50 parts by mass.

The primer ink of the present invention contains a polymerizable compound. The polymerizable compound in the present invention is a compound having a function of polymerizing or crosslinking with an initiating species such as a radical generated from a polymerization initiator or the like and curing a composition containing these.
Specifically, for example, an addition polymerizable compound having at least one ethylenically unsaturated double bond, a polymer compound having a maleimide group in the side chain, an unsaturated double bond capable of photodimerization adjacent to an aromatic nucleus And a high molecular compound having a cinnamyl group, a cinnamylidene group or a chalcone group in the side chain. Among these, a radical polymerizable compound that is polymerized by an active radical generated from the polymerization initiator is preferable.

[Radically polymerizable compound]
As the radically polymerizable compound that can be contained in the primer ink of the present invention, it is particularly preferable to use a radically polymerizable monomer that undergoes a polymerization or cross-linking reaction with an initiating species generated from a radical polymerization initiator. Further, the radical polymerizable monomer is more preferably an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is a compound selected from compounds having at least one terminal ethylenically unsaturated bond. It is particularly preferred. Examples thereof include (meth) acrylates, aromatic vinyls, vinyl ethers, and compounds having an internal double bond (such as maleic acid). The chemical forms of these compounds include monomers, prepolymers (ie, dimers, trimers and oligomers) and copolymers thereof, and mixtures thereof.

  Specifically, for example, as a monofunctional (meth) acrylate compound, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, tert-octyl (meth) acrylate, isoamyl (meth) acrylate, decyl (meth) acrylate, Isodecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-n-butylcyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, benzyl ( (Meth) acrylate, 2-ethylhexyl diglycol (meth) acrylate, butoxyethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 4-bromobutyl (meth) acryl , Cyanoethyl (meth) acrylate, benzyl (meth) acrylate, butoxymethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, alkoxymethyl (meth) acrylate, alkoxyethyl (meth) acrylate, 2- (2-methoxy Ethoxy) ethyl (meth) acrylate, 2- (2-butoxyethoxy) ethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, 1H, 1H, 2H, 2H-perfluorodecyl (meth) Acrylate, 4-butylphenyl (meth) acrylate, phenyl (meth) acrylate, 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxye (Meth) acrylate, glycidyl (meth) acrylate, glycidyloxybutyl (meth) acrylate, glycidyloxyethyl (meth) acrylate, glycidyloxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, hydroxyalkyl ( (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, dimethyl Aminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, trimethoxy Silylpropyl (meth) acrylate, trimethylsilylpropyl (meth) acrylate, polyethylene oxide monomethyl ether (meth) acrylate, oligoethylene oxide monomethyl ether (meth) acrylate, polyethylene oxide (meth) acrylate, oligoethylene oxide (meth) acrylate, oligoethylene oxide monoalkyl Ether (meth) acrylate, polyethylene oxide monoalkyl ether (meth) acrylate, dipropylene glycol (meth) acrylate, polypropylene oxide monoalkyl ether (meth) acrylate, oligopropylene oxide monoalkyl ether (meth) acrylate, 2-methacryloyloxy Tylsuccinic acid, 2-methacryloyloxyhexahydrophthal 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, butoxydiethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate (2-HPA), EO-modified phenol (meth) acrylate, EO-modified cresol (meth) acrylate, EO-modified nonylphenol (meth) acrylate, PO-modified nonylphenol (meth) acrylate, EO-modified-2-ethylhexyl (meth) acrylate, etc. Is mentioned.

  Specific examples of the bifunctional (meth) acrylate include 1,6-hexanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and 2,4-dimethyl. -1,5-pentanediol di (meth) acrylate, butylethylpropanediol (meth) acrylate, ethoxylated cyclohexanemethanol di (meth) acrylate, polyethylene glycol di (meth) acrylate, oligoethylene glycol di (meth) acrylate, Ethylene glycol di (meth) acrylate, 2-ethyl-2-butyl-butanediol di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, EO-modified bisphenol A di (meth) acrylate Bisphenol F polyethoxydi (meth) acrylate, polypropylene glycol di (meth) acrylate, oligopropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 2-ethyl-2-butylpropanediol di ( Examples include meth) acrylate, 1,9-nonanedi (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, and tricyclodecane di (meth) acrylate.

  Specific examples of trifunctional (meth) acrylates include trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane alkylene oxide-modified tri (meth) acrylate, pentaerythritol tri (meth) acrylate , Dipentaerythritol tri (meth) acrylate, trimethylolpropane tris ((meth) acryloyloxypropyl) ether, isocyanuric acid alkylene oxide modified tri (meth) acrylate, propionate dipentaerythritol tri (meth) acrylate, tris ((meta) ) Acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde-modified dimethylolpropane tri (meth) acrylate, sorbitol tri (meth) Acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and ethoxylated glycerin triacrylate.

  Specific examples of tetrafunctional (meth) acrylates include pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, propionate dipentaerythritol tetra (meth) acrylate, ethoxylated penta Examples include erythritol tetra (meth) acrylate.

  Specific examples of the pentafunctional (meth) acrylate include sorbitol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate.

  Specific examples of hexafunctional (meth) acrylate include dipentaerythritol hexa (meth) acrylate, sorbitol hexa (meth) acrylate, phosphazene alkylene oxide modified hexa (meth) acrylate, captolactone modified dipentaerythritol hexa (meth) acrylate Etc.

  Specific examples of aromatic vinyls include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, vinyl benzoic acid. Methyl ester, 3-methylstyrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4- Hexyl styrene, 3-octyl styrene, 4-octyl styrene, 3- (2-ethylhexyl) styrene, 4- (2-ethylhexyl) styrene, allyl styrene, isopropenyl styrene, butenyl styrene, octenyl Styrene, 4-t-butoxycarbonyl styrene, 4-methoxystyrene, and a 4-t-butoxystyrene.

  Specific examples of vinyl ethers include, as examples of monofunctional vinyl ethers, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, Cyclohexylmethyl vinyl ether, 4-methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether , Methoxypolye Lenglycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether Chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxypolyethylene glycol vinyl ether, and the like.

Examples of polyfunctional vinyl ethers include ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide di Divinyl ethers such as vinyl ether; trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexabi Ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether, propylene oxide-added penta And polyfunctional vinyl ethers such as erythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.
As the vinyl ether compound, a di- or trivinyl ether compound is preferable from the viewpoints of curability, adhesion to a recording medium, surface hardness of the formed image, and the like, and a divinyl ether compound is particularly preferable.

  In addition to the above, the radical polymerizable monomer in the present invention further includes vinyl esters [vinyl acetate, vinyl propionate, vinyl versatate, etc.], allyl esters [allyl acetate, etc.], halogen-containing monomers [vinylidene chloride]. , Vinyl chloride, etc.], vinyl cyanide [(meth) acrylonitrile, etc.], olefins [ethylene, propylene, etc.] and the like.

The primer ink of the present invention may contain a polymerizable compound as exemplified above alone or in combination of two or more kinds. However, the primer ink of the present invention contains 2-hydroxy-3-phenoxy as the polymerizable compound. Contains propyl acrylate.
The content of 2-hydroxy-3-phenoxypropyl acrylate in the primer ink of the present invention is preferably 5 parts by mass or more and 70 parts by mass or less, and more preferably 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the primer ink. It is below mass parts.

The polymerizable compound constituting the primer ink of the present invention is preferably a radical polymerizable monomer, and it is preferable to use a combination of a monofunctional radical polymerizable monomer and a bifunctional or higher polyfunctional radical polymerizable monomer. In particular, in the primer ink of the present invention, by using relatively large amount of polymerizable monomer monofunctional may ensure excellent fixability. Specifically, the mixing ratio of the monofunctional polymerizable monomer and the polyfunctional polymerizable monomer is preferably 10: 0 to 8: 2 in terms of mass ratio (monofunctional polymerizable monomer: polyfunctional polymerizable monomer), More preferably, it is 10: 0 to 9: 1. When the mixing ratio of the monofunctional polymerizable monomer and the polyfunctional polymerizable monomer is within the above range, a primer ink having an appropriate curing speed and viscosity can be obtained.

[Cationically polymerizable compound]
Furthermore, a cationic polymerizable compound can also be used as the polymerizable compound. The cationically polymerizable compound is not particularly limited as long as it is a compound having a function of curing a composition containing the compound by starting a cationic polymerization reaction by applying some energy, and may be in any form of a monomer, an oligomer, or a polymer. May be. In particular, a known cationically polymerizable compound known as a photocationically polymerizable compound that is polymerized by an initiating species generated from a cationic polymerization initiator can be used. Further, the cationic polymerizable compound may be either a monofunctional compound or a polyfunctional compound.

  Examples of the cationic polymerizable compound that can be contained in the primer ink of the present invention include, for example, JP-A Nos. 6-9714, 2001-31892, 2001-40068, 2001-55507, and 2001-310938. Examples thereof include epoxy compounds, vinyl ether compounds, and oxetane compounds described in JP-A Nos. 2001-310937, 2001-220526, and 2003-341217. The cationic polymerizable compound may be used alone or in combination of two or more.

As the cationically polymerizable compound that can be contained in the primer ink of the present invention, an oxirane ring-containing compound and an oxetane ring-containing compound are preferable from the viewpoint of curability and scratch resistance, and both the oxirane ring-containing compound and the oxetane ring-containing compound are used. It is more preferable to contain.
In this specification, the oxirane ring-containing compound (hereinafter sometimes referred to as “oxirane compound”) refers to a compound containing at least one oxirane ring (oxiranyl group, epoxy group) in the molecule. The oxetane ring-containing compound (hereinafter sometimes referred to as “oxetane compound”) refers to a compound containing at least one oxetane ring (oxetanyl group) in the molecule.

   The oxirane compound can be appropriately selected from those usually used as an epoxy resin. For example, conventionally known aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins and the like can be used. These may be monomers, oligomers or polymers.

  Examples of the monofunctional epoxy compound include phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, 1,2-butylene oxide, and 1,3-butadiene monooxide. 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-methacryloyloxymethylcyclohexene oxide, 3-acryloyloxymethylcyclohexene oxide, 3-vinylcyclohexene oxide, etc. It is done.

  Examples of polyfunctional epoxy compounds include, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, and brominated bisphenol. S diglycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxy 2- (3,4-epoxycyclohexyl) -7,8-epoxy-1,3-dioxaspiro [5.5] undecane, bis (3,4-epoxycyclohexyl) Silmethyl) adipate, vinylcyclohexene oxide, 4-vinylepoxycyclohexane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3 ′, 4′-epoxy-6 '-Methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, di (3,4-epoxycyclohexylmethyl) ether of ethylene glycol, ethylenebis (3,4-epoxycyclohexanecarboxylate) Dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether Glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,13-tetradecadiene dioxide, limonene dioxide, 1,2,7,8-diepoxy Examples include octane and 1,2,5,6-diepoxycyclooctane. Of these, aromatic epoxides and alicyclic epoxides are preferable from the viewpoint of excellent curing speed, and alicyclic epoxides are particularly preferable.

  Examples of the vinyl ether compound include monofunctional and polyfunctional vinyl ether compounds as exemplified in the radical polymerizable compound.

  As the oxetane compound, a compound having 1 to 4 oxetane rings in its structure is preferable. By using such a compound, it becomes easy to maintain the viscosity of the primer ink in a favorable handling property range, and it is possible to obtain high adhesion between the cured image forming ink and the recording medium. it can. In particular, from the viewpoint of the viscosity and tackiness of the primer ink, it is more preferable to use a compound having 1 to 2 oxetane rings.

  Specifically, as the monofunctional oxetane compound, for example, 3-ethyl-3-hydroxymethyloxetane, 3- (meth) allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanylmethoxy) methylbenzene, 4-fluoro- [1- (3-ethyl-3-oxetanylmethoxy) methyl [benzene, 4-methoxy- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, [1- (3-ethyl- 3-oxetanylmethoxy) ethyl] phenyl ether, isobutoxymethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyl (3-ethyl-3- Oxetanylmethyl) ether, 2-ethylhexyl (3-ethyl-3- Xetanylmethyl) ether, ethyldiethylene glycol (3-ethyl-3-oxetanylmethyl) ether, dicyclopentadiene (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, Dicyclopentenyl (3-ethyl-3-oxetanylmethyl) ether, tetrahydrofurfuryl (3-ethyl-3-oxetanylmethyl) ether, tetrabromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tetrabromophenoxy Ethyl (3-ethyl-3-oxetanylmethyl) ether, tribromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tribromophenoxyethyl (3-ethyl-3-oxetanylmethyl) Ether, 2-hydroxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxypropyl (3-ethyl-3-oxetanylmethyl) ether, butoxyethyl (3-ethyl-3-oxetanylmethyl) ether, pentachlorophenyl (3-ethyl-3-oxetanylmethyl) ether, pentabromophenyl (3-ethyl-3-oxetanylmethyl) ether, bornyl (3-ethyl-3-oxetanylmethyl) ether and the like.

  Moreover, as a polyfunctional oxetane compound, for example, 3,7-bis (3-oxetanyl) -5-oxa-nonane, 3,3 ′-(1,3- (2-methylenyl) propanediylbis (oxymethylene)) Bis- (3-ethyloxetane), 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 1,2-bis [(3-ethyl-3-oxetanylmethoxy) methyl] ethane, 1 , 3-bis [(3-ethyl-3-oxetanylmethoxy) methyl] propane, ethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenylbis (3-ethyl-3-oxetanylmethyl) ether, Triethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, tetraethylene glycol bis (3 Ethyl-3-oxetanylmethyl) ether, tricyclodecanediyldimethylene (3-ethyl-3-oxetanylmethyl) ether, trimethylolpropane tris (3-ethyl-3-oxetanylmethyl) ether, 1,4-bis (3 -Ethyl-3-oxetanylmethoxy) butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, pentaerythritol tris (3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetrakis (3-ethyl- 3-oxetanylmethyl) ether, polyethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol pentakis (3- Til-3-oxetanylmethyl) ether, dipentaerythritol tetrakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol pentane Kiss (3-ethyl-3-oxetanylmethyl) ether, ditrimethylolpropane tetrakis (3-ethyl-3-oxetanylmethyl) ether, ethylene oxide (EO) modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, Propylene oxide (PO) modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, EO modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) Examples include ether, PO-modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, and EO-modified bisphenol F (3-ethyl-3-oxetanylmethyl) ether. Such an oxetane compound is described in detail in paragraphs [0021] to [0084] of JP-A-2003-341217, and can be suitably used for the primer ink of the present invention.

  When the primer ink of the present invention contains a cationically polymerizable compound, the content thereof is preferably in the range of 50 to 95 mass%, more preferably 60 to 92 mass%, based on the solid content of the primer ink.

  The content of the polymerizable compound in the primer ink of the present invention is preferably 50 to 99.6% by mass, more preferably 60 to 99.0% by mass, based on the solid content of the primer ink.

(Polymerization initiator)
The primer ink of the present invention contains a polymerization initiator. The polymerization initiator in the present invention is a compound that generates an initiating species such as a radical by applying energy of active light, heat, or both, and initiates and accelerates the polymerization reaction or crosslinking reaction of the above-described polymerizable compound. In the present invention, the polymerization initiator is preferably one that initiates a polymerization reaction or crosslinking reaction by heat or actinic radiation, and more preferably one that initiates a polymerization reaction or crosslinking reaction by actinic radiation. When the primer ink contains a polymerization initiator, the primer ink applied to the recording medium can be cured by irradiation with actinic radiation or heating.

  When the primer ink of the present invention uses a radical polymerizable compound as the polymerizable compound, it preferably contains a polymerization initiator (radical polymerization initiator) for starting radical polymerization, and contains a cationic polymerizable compound. In some cases, it is preferable to contain a polymerization initiator (cationic polymerization initiator) that initiates cationic polymerization. Moreover, it is especially preferable that these are photoinitiators. It is preferable that the primer ink of the present invention contains a radical polymerizable compound and a radical polymerization initiator because the curing reaction can be performed in a short time.

  As the photopolymerization initiator, actinic rays to be irradiated, for example, 400 to 200 nm ultraviolet rays, far ultraviolet rays, g rays, h rays, i rays, KrF excimer laser rays, ArF excimer laser rays, electron beams, X rays, molecules A known photopolymerization initiator having sensitivity to a line, an LED beam, an ion beam, or the like can be appropriately selected and used.

  Examples of the photopolymerization initiator that can be used in the primer ink of the present invention include (a) aromatic ketones, (b) aromatic onium salts, (c) organic peroxides, (d) hexaarylbiimidazole compounds, e) ketoxime ester compounds, (f) borate compounds, (g) azinium compounds, (h) metallocene compounds, (i) active ester compounds, and (j) compounds having a carbon halogen bond.

  (A) As aromatic ketones, for example, a compound having a benzophenone skeleton or a thioxanthone skeleton, an α-thiobenzophenone compound, a benzoin ether compound, an α-substituted benzoin compound, a benzoin derivative, an aroylphosphonic acid ester, a dialkoxybenzophenone, Examples thereof include benzoin ethers, α-aminobenzophenones, p-di (dimethylaminobenzoyl) benzene, thio-substituted aromatic ketones, acyl phosphine oxides, acyl phosphines, thioxanthones, and coumarins.

  (B) Aromatic onium salts include Group V, VI and VII elements of the Periodic Table, specifically N, P, As, Sb, Bi, O, S, Se, Te, or I fragrances Group onium salts. Iodonium salts, sulfonium salts, diazonium salts (such as benzenediazonium which may have a substituent), diazonium salt resins (such as diazodiphenylamine formaldehyde resin), and N-alkoxypyridinium salts are preferably used. These generate radicals and acids as active species.

  (C) The organic peroxide includes an organic compound having one or more oxygen-oxygen bonds in the molecule.

  (D) Examples of hexaarylbiimidazole compounds include lophine dimers.

  (E) Examples of ketoxime ester compounds include 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, 3-propionyloxyiminobutan-2-one, and 2-acetoxyiminopentane-3. -One, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3-p-toluenesulfonyloxyiminotan-2-one, 2-ethoxy And carbonyloxyimino-1-phenylpropan-1-one.

(F) Examples of the borate compound include compounds described in US Pat. Nos. 3,567,453, 4,343,891, European Patents 109,772 and 109,773.
(G) Examples of azinium compounds include JP-A-63-138345, JP-A-63-142345, JP-A-63-142346, JP-A-63-143537, and JP-B-46-42363. The compound group which has the described N-O bond can be mentioned.
Examples of (h) metallocene compounds include titanocene compounds and iron-arene complexes.

(I) Examples of the active ester compound include a nitrobenzester compound and an iminosulfonate compound.
(J) Preferred examples of the compound having a carbon halogen bond include those described in Wakabayashi et al., Bull. Chem. Soc. Japan, 42, 2924 (1969). F.F. C. J. Schaefer et al. Org. Chem. 29, 1527 (1964).

Among the photopolymerization initiators, the radical polymerization initiator that can be used in the primer ink of the present invention is preferably (a) an aromatic ketone from the viewpoint of curability, and more preferably a compound having a benzophenone skeleton or a thioxanthone skeleton. An α-aminoalkylphenone compound and an acylphosphine oxide compound are particularly preferable. On the other hand, the cationic polymerization initiator is preferably an aromatic onium salt (b), more preferably an iodonium salt and a sulfonium salt, and particularly preferably a PF6 salt of iodonium and a PF6 salt of sulfonium salt from the viewpoint of curability.
These polymerization initiators can be used alone or in combination of two or more. Further, as long as the effects of the present invention are not impaired, a known sensitizer can be used in combination for the purpose of improving sensitivity.

The content of the polymerization initiator in the primer ink of the present invention is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, based on the solid content of the primer ink.
Further, the content ratio of the polymerization initiator and the polymerizable compound is preferably 0.5: 100 to 30: 100 in terms of mass ratio (polymerization initiator: polymerizable compound), and 1: 100 to 15: 100. It is more preferable that

(Coloring material)
The primer ink of the present invention may contain a colorant if the reproducibility is more excellent depending on the properties of the printed image, but for the purpose of obtaining a high-quality printed matter, the drawing ink of the image forming ink on it may be used. It is preferably transparent so as not to affect.

When the coloring material is blended with the primer ink, as the coloring material, a coloring material used in an image forming ink described later can be used, and in particular, a white coloring material can be preferably used. In addition, when a coloring material is blended, it is preferable to add a dispersant (for example, one that can be used in the image forming ink described later).
When the primer ink of the present invention contains a colorant, the content thereof is preferably 0.1 to 30% by mass, and 0.5 to 20% by mass with respect to the total mass of the primer ink. Is more preferable.

(Surface conditioner)
In order to improve the wettability with respect to the recording medium and prevent repelling, the primer ink of the present invention preferably contains a surface conditioner.
Specific examples of the surface conditioner that can be used in the present invention include anionic surface conditioners such as dialkylsulfosuccinates, alkylnaphthalenesulfonates and fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers. , Nonionic surface conditioners such as acetylene glycols and polyoxyethylene / polyoxypropylene block copolymers, cationic surface conditioners such as alkylamine salts and quaternary ammonium salts, silicon-based surface conditioners and fluorine-based surface conditioners Agents and the like.

  The content of the surface conditioner contained in the primer ink of the present invention is appropriately selected depending on the intended use, but is generally 0.0001 to 1% by mass with respect to the total mass of the primer ink. Is preferred. The surface tension of the primer ink can be adjusted by adjusting the addition amount of the surface conditioner as necessary within the above range.

[Sensitizer]
The primer ink of the present invention may contain a sensitizing dye as a sensitizer for the purpose of improving the sensitivity of the photopolymerization initiator. Examples of preferred sensitizing dyes include the following compounds: polynuclear aromatics, xanthenes, cyanines, merocyanines, thiazines, acridines, anthraquinones or coumarins, and in the 350 nm to 450 nm range. Mention may be made of those having an absorption wavelength.

[Co-sensitizer]
Moreover, you may add the well-known compound which has an effect | action etc. which improve a sensitivity further or suppress the superposition | polymerization inhibition by oxygen as a co-sensitizer. Examples of co-sensitizers include amines, and specific examples include triethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, and p-methylthiodimethylaniline.

[Anti-gelling agent]
The primer ink of the present invention may contain an anti-gelling agent from the viewpoint of improving storage stability and preventing head clogging due to thermal polymerization. Examples of the anti-gelling agent include hydroquinone, benzoquinone, p-methoxyphenol, hydroquinone monomethyl ether, hydroquinone monobutyl ether, TEMPO, TEMPOL, cuperon Al, IRGASTAB UV-10, IRGASTAB UV-22, and FIRSTCURE ST-1 (ALBEMARLE Etc.). When the gelling inhibitor is contained, the content is preferably added in an amount of 200 to 20,000 ppm based on the total amount of the primer ink.

〔solvent〕
The primer ink of the present invention may contain a known solvent as necessary. The solvent can be used for the purpose of improving the polarity and viscosity of the primer ink, the surface tension, the solubility and dispersibility of the coloring material, adjusting the conductivity, and adjusting the printing performance.

  As the solvent, a high-boiling organic solvent having a property excellent in compatibility with a constituent material, particularly with a monomer, is preferable. Known solvents include low-boiling organic solvents that are organic solvents at 100 ° C. or lower. However, there is a concern of affecting the curability, and it is desirable not to use them in consideration of environmental contamination by low-boiling organic solvents. When used, it is preferable to use a highly safe [solvent having a high management concentration (an index indicated by the work environment evaluation criteria)], for example, a management concentration of 100 ppm or more is preferable, and 200 ppm or more is further preferable. preferable. Examples of such a solvent include alcohols, ketones, esters, ethers, hydrocarbons, and the like, specifically, methanol, 2-butanol, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, and the like. It is done.

  A solvent can be used individually by 1 type or in combination of 2 or more types. When water and / or a low-boiling organic solvent is used, the amount of both used is preferably 0 to 20% by weight in the primer ink, more preferably 0 to 10% by weight, and substantially It is preferably not included. Also, from the point of stability over time such as non-uniformity over time, turbidity of liquid due to dye precipitation, etc., and from the point of drying when using a non-permeable or slowly permeable recording medium The primer ink of the present invention preferably contains substantially no water. Note that “substantially free” means accepting the presence of inevitable impurities.

[Other ingredients]
The primer ink of the present invention may further contain a storage stabilizer, a conductive salt, and other additives depending on the purpose.
As other additives, known additives such as polymers, ultraviolet absorbers, antioxidants, anti-fading agents, and pH adjusters can be appropriately selected and used. Specifically, for example, additives described in JP-A No. 2001-181549 can be used for the ultraviolet absorber, antioxidant, fading inhibitor, and pH adjuster.

  In addition, a set of compounds that react to produce agglomerates or thicken can be contained, for example, separately for the primer ink of the present invention and the image forming ink used together with the primer ink. . The one set of compounds has a feature of rapidly forming aggregates or rapidly thickening ink liquid, thereby more effectively suppressing coalescence between adjacent droplets. be able to.

The primer ink of the present invention is coated on a recording medium by an ink jet method. For this reason, the physical properties of the primer ink must be compatible with the ink jet method.
Specifically, the surface tension of the primer ink of the present invention is 25 to 31 mN / m. If the surface tension of the primer ink is less than 25 mN / m, the image forming ink may be easily repelled during image formation, and the image may not be drawn. On the other hand, if the surface tension exceeds 31 mN / m, the image forming ink may be used during image formation. May spread easily. Further, if the range of 25 to 31 mN / m is greatly deviated, the ink may not be suitable for IJP, and the ink itself may cause ejection failure.

  Further, the viscosity of the primer ink of the present invention at 25 ° C. is 50 mPa · s or less. This is because, when the viscosity is higher than 50 mPa · s, the ejection performance from the ink head is lowered when ejecting by the ink jet method. In addition, although there is no restriction | limiting in particular about the lower limit of the viscosity of primer ink, Usually, it is about 3.0 mPa * s.

  In general, in an ink jet recording method, adjacent ink droplets applied with overlapping portions to obtain a high image density stay on and contact with a recording medium before drying. Are combined with each other to cause blurring of the image and non-uniformity of the line width of the fine lines, and sharp image formation tends to be impaired. In the present invention, by using the primer ink of the present invention to form a primer layer on the recording medium, adjacent ink droplets are caused by the interaction between the primer ink and the ink droplets that form an image. The unity between them can be suppressed. This effectively prevents blurring of the image, non-uniform line width such as fine lines in the image, and color unevenness on the colored surface.

  Here, the adjacent ink droplets are droplets that are ejected from an ink ejection port using a single color ink, and are ejected with overlapping portions, or inks of different colors are used. This means a droplet ejected from an ink ejection port and ejected with an overlapping portion. Adjacent ink droplets may be droplets that are ejected at the same time, or may be preceding droplets and subsequent droplets that have a relationship between preceding droplet ejection and subsequent droplet ejection.

Therefore, the primer ink of the present invention is used together with at least one image forming ink as a liquid for forming an image.
In the present invention, the image forming ink used together with the primer ink of the present invention is not particularly limited, and a known ink composition conventionally used in an ink jet method can be used. An ink composition using a colorant compound and a pigment as a coloring material is preferable.
Hereinafter, an image forming ink particularly suitable for use with the primer ink of the present invention will be described. In the present specification, hereinafter, the “image forming ink composition” means an individual ink composition constituting an image forming ink used for image formation (usually an image forming ink). Is composed of a plurality of image forming ink compositions).

  The image forming ink composition is configured to be at least a composition for forming an image. Specifically, for example, it contains at least one polymerizable compound and a coloring material, and is composed of a polymerization initiator, a surface conditioner, an antigelling agent, other additives, and the like as necessary.

  As the polymerizable compound, for example, radically polymerizable compounds and cationically polymerizable compounds exemplified as those that can be used in the primer ink of the present invention can be appropriately selected and used. A radical polymerizable compound and a cationic polymerizable compound may be used in combination, or only one of them may be used.

  As the polymerizable compound used in the image forming ink composition, (meth) acrylates and (meth) acrylamides are preferable from the viewpoint of curing speed. In particular, it is preferable to mainly use a polyfunctional polymerizable compound, and it is preferable to contain a tetrafunctional or higher functional (meth) acrylate. Furthermore, from the viewpoint of reducing the viscosity of the ink composition for image formation and improving the adhesion, trifunctional or higher polyfunctional (meth) acrylate and monofunctional (meth) acrylate or bifunctional (meth) acrylate or (meth) It is preferable to use acrylamide together.

The mixing ratio of the monofunctional polymerizable compound to the polyfunctional polymerizable compound in the image forming ink composition is 9: 1 to 1: 9 in terms of mass ratio (monofunctional polymerizable compound: polyfunctional polymerizable compound). It is preferably 8: 2 to 2: 8, more preferably 4: 6 to 2: 8. When the mixing ratio of the monofunctional polymerizable compound and the polyfunctional polymerizable compound is within the above range, the ink composition for image formation having an appropriate curing speed and viscosity is obtained.
The content of the polymerizable compound is preferably 50 to 99.6% by mass, and preferably 60 to 99.0% by mass, based on the solid content (mass) of the image forming ink composition.

  As a polymerization initiator, the photoinitiator illustrated as what can be used for the primer ink of this invention, for example can be selected suitably, and can be used. When a radical polymerizable compound is used as the polymerizable compound, a radical polymerization initiator is preferably used, and when a cationic polymerizable compound is used, a cationic polymerization initiator is preferably used.

  As the radical polymerization initiator, from the viewpoint of curability, aromatic ketones are preferable, compounds having a benzophenone skeleton or a thioxanthone skeleton are more preferable, and α-aminoalkylphenone compounds and acylphosphine oxide compounds are particularly preferable. On the other hand, the cationic polymerization initiator is preferably an aromatic onium salt, more preferably an iodonium salt or a sulfonium salt, and particularly preferably an iodonium PF6 salt or a sulfonium salt PF6 salt from the viewpoint of curability. A polymerization initiator can be used individually or in combination of 2 or more types. Moreover, it can also use together with a well-known sensitizer for the purpose of a sensitivity improvement.

  The polymerization initiator is preferably selected and contained as long as the storage stability of the image forming ink composition can be maintained to a desired level. The content is, for example, preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass with respect to the solid content of the image forming ink composition. Further, the content ratio of the polymerization initiator and the polymerizable compound is preferably 0.5: 100 to 30: 100 in terms of mass ratio (polymerization initiator: polymerizable compound), and 1: 100 to 15: 100. It is more preferable that

  The image forming ink is usually a multicolor ink set composed of a plurality of image forming ink compositions. The ink for image formation basically includes a cyan ink composition (cyan ink composition), a magenta ink composition (magenta ink composition), a yellow ink composition (yellow ink composition), black It is preferable to include at least one colored ink composition selected from the group consisting of a color ink composition (black ink composition) and a white color ink composition (white ink composition). In some cases, an image having excellent color reproducibility can be formed by using special colors such as violet, blue, green, orange and red.

  Accordingly, the image forming ink composition preferably contains at least one colorant. Each color image forming ink composition contains at least one colorant exhibiting a corresponding color. The colorant used in the image forming ink composition is not particularly limited and can be appropriately selected from known water-soluble dyes, oil-soluble dyes, pigments, and the like, but the primer ink of the present invention is non-aqueous. Therefore, the colorant of the image forming ink composition used together with the primer ink of the present invention is preferably an oil-soluble dye or pigment that is easily dispersed and dissolved uniformly in a water-insoluble medium, and it is particularly preferable to use a pigment. .

As the pigment, either an organic pigment or an inorganic pigment can be used.
Preferred examples of the black pigment include carbon black pigments. In general, black and three primary color pigments of cyan, magenta and yellow are used, but other hues, for example, metallic luster pigments such as gold and silver, colorless or light-colored extender pigments, etc. may be used depending on the purpose. Can be used.

  As a magenta color, C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as CI Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Azo lake pigments such as C.I. Pigment Red 57: 1 (Brilliant Carmine 6B); I. Condensed azo pigments such as C.I. Pigment Red 144 (condensed azo red BR and the like), C.I. I. Perinone pigments such as CI Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (perylene scarlet, etc.), C.I. I. Pigment Violet 19 (unsubstituted quinacridone, CINQUASIA Magenta RT-355T; manufactured by Ciba Specialty Chemicals), C.I. I. Quinacridone pigments such as C.I. Pigment Red 122 (quinacridone magenta, etc.); I. Isoindolinone pigments such as CI Pigment Red 180 (such as Isoindolinone Red 2BLT); I. And alizarin lake pigments such as CI Pigment Red 83 (Madder Lake, etc.).

  As a pigment exhibiting a cyan color, C.I. I. Disazo pigments such as CI Pigment Blue 25 (dianisidine blue, etc.); I. Pigment blue 15, C.I. I. Phthalocyanine pigments such as C.I. Pigment Blue 15: 3 (IRGALITE BLUE GLO; manufactured by Ciba Specialty Chemicals) (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as CI Pigment Blue 24 (Peacock Blue Lake, etc.), and C.I. I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).

  As a substance exhibiting a yellow color, C.I. I. Pigment Yellow 1 (Fast Yellow G, etc.), C.I. I. Monoazo pigments such as CI Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow AAA, etc.), C.I. I. Disazo pigments such as C.I. Pigment Yellow 17; I. Pigment yellow 180, C.I. I. Non-benzidine type azo pigments such as CI Pigment Yellow 200 (Novoperm Yellow 2HG); I. Azo lake pigments such as C.I. Pigment Yellow 100 (such as Tartrazine Yellow Lake); I. Condensed azo pigments such as C.I. Pigment Yellow 95 (condensed azo yellow GR and the like), C.I. I. Pigment Yellow 115 (quinoline yellow lake, etc.), etc., acidic dye lake pigments, C.I. I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and Quinophthalone Yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as CI Pigment Yellow 153 (such as Nickel Nitroso Yellow), and C.I. I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.).

  Examples of black pigments include carbon black, titanium black, and aniline black. Examples of the carbon black include SPECIAL BLACK 250 (manufactured by Degussa).

Examples of white pigments include Pigment White 6, 18, and 21. Specific examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white). ), Strontium titanate (SrTiO ₃ , so-called titanium strontium white), and the like can be used. Titanium oxide has a lower specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, so it has a high hiding power and coloring power as a pigment, and it also has acid, alkali, and other environments. Excellent durability against. Therefore, it is preferable to use titanium oxide as the white pigment. Other white pigments (may be other than the listed white pigments) may be used as necessary.

  Among these known pigments, the cyan pigment is preferably pigment blue 15: 3 or pigment blue 15: 4, and the magenta pigment is pigment red 122, pigment red 202, or pigment violet 19. The pigment exhibiting a yellow color is more preferably Pigment Yellow 150, Pigment Yellow 180, or Pigment Yellow 155. Moreover, it is preferable that the pigment which exhibits a white color is a titanium oxide.

In order to form an image excellent in color reproducibility, the following pigments may be used as special color pigments such as violet, blue, green, orange and red, if necessary.
Examples of pigments exhibiting a violet color include C.I. I. Pigment violet 1 (rhodamine B), C.I. I. Pigment violet 2 (rhodamine 3B), C.I. I. Pigment violet 3 (methyl violet lake), C.I. I. Pigment violet 3: 1 (methyl violet lake), C.I. I. Pigment violet 3: 3 (methyl violet lake), C.I. I. Pigment Violet 5: 1 (Alizarin Maroon), C.I. I. Pigment violet 13 (ultramarine pink), C.I. I. Pigment violet 17 (naphthol AS), C.I. I. Pigment violet 23 (dioxazine violet), C.I. I. Pigment violet 25 (naphthol AS), C.I. I. Pigment violet 29 (perylene violet), C.I. I. Pigment violet 31 (violanslon violet), C.I. I. Pigment Violet 32 (Benzimidazolone Bordeaux HF3R), C.I. I. Pigment violet 36 (thioindigo), C.I. I. Pigment violet 37 (dioxazine violet), C.I. I. Pigment Violet 42 (Quinacridone Maroon B), C.I. I. Pigment Violet 50 (Naphthol AS) and the like are commercially available.

  Examples of pigments exhibiting a blue color include C.I. I. Pigment blue 1, C.I. I. Pigment blue 2, C.I. I. Pigment blue 16, C.I. I. Pigment blue 22, C.I. I. Pigment blue 60, C.I. I. Pigment Blue 66 and the like are commercially available.

  Examples of the pigment exhibiting a green color include C.I. Pigment Green 1 (Brilliant Green Lake), C.I. Pigment Green 4 (Malachite Green Lake), C.I. Pigment Green 7 (phthalocyanine green), C.I. Pigment Green 8 (Pigment Green B), C.I. Pigment green 10 (nickel azo yellow), C.I. I. Pigment Green 36 (brominated phthalocyanine green) and the like are commercially available.

  Examples of the pigment exhibiting an orange color include C.I. I. Pigment Orange 1 (Hansa Yellow 3R), C.I. I. Pigment orange 2 (orthonitro orange), C.I. I. Pigment orange 3 (β-naphthol), C.I. I. Pigment Orange 4 (Naphthol AS), C.I. I. Pigment orange 5 (β-naphthol), C.I. I. Pigment orange 13 (pyrazolone orange G), C.I. I. Pigment orange 15 (disazo orange), C.I. I. Pigment orange 16 (anisidine orange), C.I. I. Pigment Orange 17 (Persian Orange Lake), C.I. I. Pigment Orange 19 (Naphthalene Yellow Lake), C.I. I. Pigment orange 24 (naphthol orange Y), C.I. I. Pigment orange 31 (condensed azo orange), C.I. I. Pigment orange 34 (piazolone orange), C.I. I. Pigment Orange 36 (Benzimidazolone Orange HL), C.I. I. Pigment orange 38 (naphthol orange), C.I. I. Pigment orange 40 (pyranthron orange), C.I. I. Pigment orange 43 (perinone orange), C.I. I. Pigment Orange 46 (Ethyl Red Lake C), C.I. I. Pigment orange 48 (quinacridone gold), C.I. I. Pigment Orange 49 (Quinacridone Gold), C.I. I. Pigment orange 51 (pyranthrone orange), C.I. I. Pigment Orange 60 (Imidazolone Orange HGL), C.I. I. Pigment orange 61 (isoindolinone orange), C.I. I. Pigment Orange 62 (Benzimidazolone Orange H5G), C.I. I. Pigment orange 64 (benzimidazolone), C.I. I. Pigment orange 65 (azomethine orange), C.I. I. Pigment Orange 66 (Isoindori Orange), C.I. I. Pigment orange 67 (pyrazoloquinazolone orange), C.I. I. Pigment orange 68 (azomethine orange), C.I. I. Pigment orange 69 (isoindolinone orange), C.I. I. Pigment orange 71 (diketopyrrolopyrrole orange), C.I. I. Pigment orange 72 (imidazolone orange H4GL), C.I. I. Pigment orange 73 (diketopyrrolopyrrole orange), C.I. I. Pigment orange 74 (naphthol orange 2RLD), C.I. I. Pigment Orange 81 (diketopyrrolopyrrole orange) and the like are commercially available.

  Examples of the pigment exhibiting a red color include C.I. I. Pigment red 171, C.I. I. Pigment red 175, C.I. I. Pigment red 176, C.I. I. Pigment red 177, C.I. I. Pigment red 209, C.I. I. Pigment red 220, C.I. I. Pigment red 224, C.I. I. Pigment red 242, C.I. I. Pigment red 254, C.I. I. Pigment red 255, C.I. I. Pigment red 264, C.I. I. Pigment Red 270 and the like are commercially available.

  Of these, from the viewpoint of color reproducibility, light resistance and pigment dispersion stability, C.I. I. Pigment Violet 23 is C.I. I. Pigment orange 36, C.I. I. Pigment Orange 71 is C.I. as a pigment exhibiting a green color. I. Pigment green 7, C.I. I. Pigment Green 36 is preferable.

  In the present invention, the ink composition for image formation containing the above-mentioned special color pigment and a pigment and / or dye of cyan, magenta, yellow, black (black) or white (white) are contained. It is preferable to use each color image forming ink composition.

For dispersion of the coloring material, for example, bead mill, ball mill, sand mill, attritor, roll mill, jet mill, homogenizer, paint shaker, kneader, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, etc. Can be used. A dispersing agent can be added when dispersing the coloring material.
Moreover, when adding a coloring material, it is also possible to use the synergist according to various coloring materials as a dispersing aid as needed. As a dispersion medium for various components such as a coloring material, a solvent may be added, or a polymerizable compound which is a low molecular weight component without a solvent may be used as a dispersion medium. Since the primer ink of the present invention is preferably an energy ray curable liquid, the image forming ink composition used therewith is also preferably an energy ray curable liquid. These are preferably solvent-free in order to be cured after being applied on the recording medium. This is because if the solvent remains in the formed image, the solvent resistance of the image is lowered, and the problem of VOC (Volatile Organic Compound) of the remaining solvent occurs. From such a viewpoint, it is preferable to use a polymerizable compound as a dispersion medium, and in particular, to select a polymerizable compound having a low viscosity from the viewpoint of improving dispersibility and handling properties of the ink composition.

The finer the average particle diameter of the colorant used, the better the color developability. Therefore, the average particle diameter of the colorant is preferably 0.01 μm or more and 0.4 μm or less, and preferably 0.02 μm or more and 0.2 μm or less. Further preferred. It is preferable to set the colorant, the dispersant, the dispersion medium, the dispersion conditions, and the filtration conditions so that the maximum particle size is preferably 3 μm or less, more preferably 1 μm or less. By controlling the particle size, clogging of the head nozzle can be suppressed, and the storage stability, transparency, and curing sensitivity of the ink liquid can be maintained.
The particle size of the colorant can be measured by a known measurement method. Specifically, for example, it can be measured by centrifugal sedimentation light transmission method, X-ray transmission method, laser diffraction / scattering method or dynamic light scattering method.

The content of the colorant in the image forming ink composition is appropriately selected depending on the color and purpose of use, but is 0 with respect to the total mass of the image forming ink composition from the viewpoint of image density and storage stability. It is preferably 1 to 30% by mass, more preferably 0.5 to 20% by mass.
Colorants may be used alone or in combination of two or more. Two or more kinds of organic pigments or solid solutions of organic pigments can be used in combination. Furthermore, a different coloring material may be used for each droplet and liquid to be ejected, or the same coloring material may be used.

It is preferable to add a dispersant when dispersing the coloring material. The type of the dispersant is not particularly limited, but a known polymer dispersant is preferably used. Examples of the polymeric dispersing agent include DisperBYK-101, DisperBYK-102, DisperBYK-103, DisperBYK-106, DisperBYK-111, DisperBYK-161, DisperBYK-162, DisperBYK-163, DisperBYK-164, DisperBYK-164, -167, DisperBYK-168, DisperBYK-170, DisperBYK-171, DisperBYK-174, DisperBYK-182 (manufactured by BYK Chemie), EFKA4010, EFKA4046, EFKA5080, EFKA5010, EFKA5010, EFKA5010, EFKA5010, EFKA5010, EFKA5010 Polymer dispersing agents such as KA7462, EFKA7500, EFKA7570, EFKA7575, EFKA7580 (manufactured by Fuka Additive), Disperse Aid 6, Disperse Aid 8, Disperse Aid 15, Disperse Aid 9100 (San Nopco); Solsperse) 3000, 5000, 9000, 12000, 13240, 13940, 17000, 24000, 26000, 28000, 32000, 36000, 39000, 41000, 71000, etc. (Avicia); Adeka Pluronic L31, F38, L42, L44, L61, L64, F68, L72, P95, F77, P84, F87, P94, L101, P103, F108, L121, P- 23 (manufactured by Asahi Denka Co., Ltd.) and Isonet S-20 (manufactured by Sanyo Chemical Co., Ltd.) “Disparon KS-860, 873SN, 874 (polymer dispersing agent), # 2150 (aliphatic polyvalent carboxylic acid) manufactured by Enomoto Kasei Co., Ltd. Acid), # 7004 (polyether ester type) ”.
In addition, pigment derivatives such as a phthalocyanine derivative (trade name: EFKA-745 (manufactured by Efka)), Solsperse 5000, 12000, Solsperse 22000 (manufactured by Avicia) can also be used. By using the dispersant having excellent dispersibility and stability, a uniform and stable dispersion can be obtained even when a fine particle colorant is used.

  The content of the dispersant is appropriately selected depending on the purpose of use, but is preferably 0.01 to 5% by mass with respect to the total mass of the image forming ink composition.

  As the surface conditioner, for example, those exemplified as those that can be used in the primer ink of the present invention can be appropriately selected and used. In order to realize long-term stable dischargeability, it is preferable to contain a surface conditioner. The content is appropriately selected depending on the purpose of use, but in general, the content is preferably 0.0001 to 1% by mass relative to the total mass of the image forming ink composition.

  As the gelling inhibitor, for example, those exemplified as those that can be used in the primer ink of the present invention can be appropriately selected and used. The ink composition for image formation is preferably heated at a temperature in the range of 40 to 80 ° C., and is discharged after being reduced in viscosity. Therefore, it is preferable to contain an antigelling agent in order to prevent head clogging by thermal polymerization. . The content is preferably 200 to 20,000 ppm based on the total amount of the image forming ink composition.

  In addition to the above components, the image forming ink composition used with the primer ink of the present invention includes a sensitizer, a co-sensitizer, a storage stabilizer, a conductive salt, a solvent, and other additives depending on the purpose. Can be used together. As these components, those exemplified as those that can be used in the primer ink of the present invention can be appropriately selected and used.

  The surface tension of the image forming ink composition used together with the primer ink of the present invention is preferably 25 to 32 mN / m.

  In the inkjet recording method using the primer ink of the present invention, any of a permeable recording medium, a non-permeable recording medium, and a slowly permeable recording medium can be used as the recording medium.

  Among others, the effect of the present invention is more remarkably exhibited in non-permeable and slowly permeable recording media. Here, in this specification, the permeable recording medium refers to, for example, the time until the entire liquid amount permeates when an ink droplet of 10 pL (picoliter) is dropped on the recording medium. A recording medium that has a millisecond or less. Further, the non-permeable recording medium refers to a recording medium in which liquid droplets do not substantially permeate. “Substantially does not penetrate” means, for example, that the penetration rate of a droplet after 1 minute is 5% or less. Further, the slow-penetrating recording medium refers to a recording medium in which when a 10 pL droplet is dropped on the recording medium, the time until the entire liquid amount permeates is 100 milliseconds or more.

  Examples of the permeable recording medium include plain paper, porous paper, and other recording media that can absorb liquid. Examples of the non-permeable or slowly permeable recording medium include art paper, synthetic resin, rubber, resin-coated paper, glass, metal, earthenware, and wood. In the present invention, it is also possible to use a recording medium obtained by combining a plurality of these materials for the purpose of adding functions.

  As the synthetic resin, any synthetic resin can be used. For example, polyesters such as polyethylene terephthalate and polybutadiene terephthalate, polyolefins such as polyvinyl chloride, polystyrene, polyethylene, polyurethane, and polypropylene, acrylic resins, polycarbonates, acrylonitrile-butadiene- Examples thereof include styrene copolymers, diacetate, triacetate, polyimide, cellophane, celluloid and the like. The thickness and shape of the recording medium when synthetic resin is used are not particularly limited, and may be any of a film shape, a card shape, and a block shape. Further, it may be either transparent or opaque.

  As a usage form of the synthetic resin, it is also preferable to use it in the form of a film used for so-called soft packaging, and various non-absorbable plastics and films thereof can be used. Examples of the plastic film include PET film, OPS film, OPP film, PNY film, PVC film, PE film, TAC film, PP film, and the like. Other plastics that can be used include polycarbonate, acrylic resin, ABS, polyacetal, PVA, and rubbers.

  Examples of the resin-coated paper include a transparent polyester film, an opaque polyester film, an opaque polyolefin resin film, and a paper support in which both surfaces of paper are laminated with a polyolefin resin. Particularly preferred is a paper support in which both sides of the paper are laminated with a polyolefin resin.

  There is no restriction | limiting in particular as a metal, For example, aluminum, iron, gold | metal | money, silver, copper, nickel, titanium, chromium, molybdenum, silicon, lead, zinc, stainless steel, etc., and these composite materials are mentioned.

When recording an image on a hard-to-adhere recording medium made of a non-permeable or slow-penetrating synthetic resin with low liquid absorbency, the adhesion is improved by using the primer ink of the present invention. Is particularly effective. As a recording medium on which the primer ink of the present invention is effective, a recording medium that is not particularly permeable (for example, OPP (Oriented Polypropylene Film), CPP (Casted Polypropylene Film), PE (Polyethylene), PET (Polyethylene terephthalate). PP (Polypropylene), metal plate, soft wrapping material with low permeability, laminated paper, coated paper, art paper, and the like, and when these are used, a good image can be formed.
In addition, the primer ink of the present invention can realize excellent image fixability on a recording medium made of an inorganic material (for example, glass).

A preferable ink jet recording method using the primer ink of the present invention is for image formation in which a primer layer is applied onto a recording medium by an ink jet method, and simultaneously or / immediately thereafter, the primer layer is cured by irradiation with energy rays. In this method, the ink composition is ejected, and the ink composition for image formation is cured by energy rays.
Depending on the desired image, only one color image forming ink composition may be ejected, but in order to form a full color image, a multicolor image forming ink composition is ejected sequentially or simultaneously. Form. The image is optical information including characters, diagrams, photographs, and the like, and may be monochrome, monocolor, or full color.

  In the present invention, it is preferable to apply primer ink to the same region as the image formed by discharging the image forming ink composition onto the recording medium or a region wider than the image. That is, one of the specific embodiments of the ink jet recording method using the primer ink of the present invention is an image formed by droplets of a plurality of colors of the ink composition for image formation ejected onto a recording medium. A step of applying the primer ink of the present invention to the same or a wider range than the image, a step of applying active energy rays or heat to the primer ink applied on the recording medium, and a recording target to which the primer ink has been applied Ejecting droplets of a plurality of color ink-forming ink compositions on a medium.

  In order to realize this, the primer ink in the present invention is preferably used as one of the ink sets at the same time when a plurality of color image forming inks are used as a multicolor ink set. That is, an easy way to realize this is to make at least one ink case constituting the multi-pass ink set into an ink case filled with the primer ink of the present invention.

  In addition, a step of preliminarily applying a primer ink on a recording medium, and then fixing the recorded image by applying energy after at least all of the image forming ink is deposited in order to obtain excellent fixability. The method of providing may be sufficient. By applying energy, a curing reaction by polymerization or crosslinking of the polymerizable compound contained therein can be promoted, and a stronger image can be formed more efficiently. For example, in a system including a polymerization initiator, generation of active species from the polymerization initiator is promoted by application of active energy such as active energy rays or heating, and polymerization due to the active species is caused by an increase in active species or a temperature rise. The curing reaction by polymerization or crosslinking of the functional compound is promoted.

  The application of energy can be suitably performed by irradiation of conventionally known energy rays (energy rays are also referred to as actinic radiation) or heating. As the energy ray, the same light as the active light for fixing an image can be used, and examples thereof include LED light, ultraviolet light, visible light, and α-ray, γ-ray, X-ray, electron beam, and the like. From the viewpoint of cost and safety, ultraviolet rays and visible rays are preferable. Suitable light sources for exposure include metal halide lamps, xenon lamps, tungsten lamps, carbon arc lamps, mercury lamps, and the like.

When the energy is applied by irradiation with active light, the amount of energy required for curing reaction varies depending on the type and content of the polymerization initiator, the degree typically 100 mJ / cm ² or more 10,000 / cm ² or less preferable. Further, when energy is applied by heating, it is preferable to heat for 0.1 to 1 second under the condition that the surface temperature of the recording medium is in a temperature range of 40 to 80 ° C.

  Hereinafter, the image forming process using the primer ink of the present invention will be described in more detail.

[Curing process of primer solution]
In the present invention, the primer ink itself is also applied to the recording medium by an ink jet method. Therefore, as described above, when a multi-color image forming ink composition is used as a multicolor ink set, it is preferable to simultaneously use the primer ink as one of the ink sets. Therefore, the curing process of the primer ink is determined by the configuration of the ink jet recording method and apparatus.

  That is, if the ink jet recording method / apparatus is a single pass and a method in which a head dedicated to primer ink and a radiation irradiation device are installed, after the primer liquid is cured, image forming ink is applied thereon. . In the multi-pass method, even when the primer ink is applied almost simultaneously with the image forming ink, the image forming ink is ejected after the primer ink is cured, although there is a slight time difference. The primer ink of the present invention can be applied to any of the above-mentioned methods, but the latter method is preferable from the viewpoint of operability and productivity from an industrial viewpoint.

[Applying primer solution and image forming ink]
In the present invention, the primer ink can be applied onto a recording medium using a coating apparatus or an inkjet nozzle. In addition, the image forming ink is ejected using an inkjet nozzle or the like and applied onto the primer layer.

(I) Discharge by inkjet nozzle
When the primer ink is ejected from the ink jet nozzle, although there is a slight time lag, it is preferable that the image is formed by ejecting the image forming ink by the ink jet nozzle almost simultaneously.

  As a condition for applying the primer ink by the ink jet nozzle, for example, a head having a larger ejection droplet amount and a lower nozzle density than the head for ejecting the image forming ink is fully applied in the width direction of the recording medium. It is arranged as a line head unit, thereby discharging the primer solution. Such a head with a large amount of ejected droplets generally has a large ejection force, so it can easily cope with a high-viscosity primer ink and is also advantageous in suppressing nozzle clogging. In addition, when a head with a large amount of ejected droplets is used, there is an advantage that an inexpensive head with a low driving frequency can be applied because the droplet resolving power of the primer ink in the transport direction of the recording medium can be reduced.

(Ii) Coating using a coating device When a primer ink is coated on a recording medium using a coating device, ink droplets for image formation can be ejected by an inkjet nozzle thereafter.

  In any of the above embodiments, in addition to the primer ink and the image forming ink, other liquids other than these can be further applied. The application of the other liquid may be performed by any method such as application by an application apparatus or ejection by an inkjet nozzle, and the application timing is not particularly limited. When the other liquid contains a colorant, it is preferably ejected by an ink jet nozzle and is preferably applied after the primer ink is applied.

  As an ink jet recording method, for example, an electrostatic attraction method in which ink liquid is ejected using electrostatic force, a drop-on-demand method (pressure pulse method) in which vibration pressure of a piezo element is used, an electric signal is converted into an acoustic beam, and ink is used. A known method such as an acoustic ink jet method that irradiates the liquid and discharges the ink liquid using the radiation pressure, a thermal ink jet method that heats the ink liquid to form bubbles, and uses the generated pressure, is preferably used. obtain. Inkjet recording methods include a method of ejecting many low-density ink liquids called photo inks in a small volume, a system for improving image quality using a plurality of ink liquids having substantially the same hue and different concentrations, and colorless and transparent. The method using the ink liquid is included.

  In the present invention, the droplets of the image forming ink ejected on the primer ink are preferably ejected with a droplet size of 0.1 pL or more and 100 pL or less (preferably by an inkjet nozzle), and 0.5 pL. More preferably, droplets are ejected with a droplet size of 50 pL or less. When the droplet size is within the above range, it is effective in that the image can be drawn with a high sharpness image density.

  Further, the applied amount (weight ratio per unit area) of the primer ink is preferably in the range of 0.05 to 5 when the droplet amount of the image forming ink is 1, and preferably 0.07 to A range of 4 is more preferable, and a range of 0.1 to 3 is particularly preferable.

  The thickness of the primer liquid layer formed by applying the primer ink on the recording medium (base material) and the undercoat layer obtained by curing the primer liquid layer is preferably 1 μm or more and 20 μm or less, and preferably 2 μm or more and 10 μm or less. More preferably, it is 3 μm or more and 8 μm or less. It is preferable that the thickness of the primer liquid layer and the undercoat layer be within the above range because the flexibility and adhesion of the cured image can be maintained well.

  It is preferable that the droplet ejection interval from the application of the primer ink to the ejection of the image forming ink is in the range of 5 microseconds to 10 seconds. It is effective in that the effect of the present invention can be remarkably exhibited when the droplet ejection interval is within the above range. The droplet ejection interval of the ink droplets is more preferably 10 microseconds to 5 seconds, and particularly preferably 20 microseconds to 5 seconds.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not restrict | limited to these. In the table below, “parts” represents parts by mass.

  Table 1 shows the components of the primer ink and the image forming ink composition used in each example and comparative example.

In each example and comparative example, the following non-permeable base material was used as a recording medium.
Glass: S9111 manufactured by MATSANAMI
Glass epoxy: Shin-Kobe Electric KEL-GEF
Nylon plate: 6 nylon plate manufactured by Toyo Plastic Seiko Co., Ltd.

[Preparation of primer ink]
Example 1
Each component was measured so that it might become a composition shown in Table 2, and the mixture was stirred for 30 minutes with the magnetic stirrer. After stirring, this mixture was suction filtered using a glass filter (manufactured by Kiriyama Seisakusho) to prepare a primer ink for forming a primer layer.

Examples 2 to 13 and Comparative Examples 1 to 6
Primer inks were prepared in the same manner as in Example 1 so that the compositions shown in Table 2 (Examples 1 to 10) or Table 3 (Examples 11 to 13 and Comparative Examples 1 to 6) were obtained.

  Viscosity and surface tension of the primer inks of Examples and Comparative Examples prepared as described above were measured by the following methods. The results are shown in Table 5.

[viscosity]
The viscosity was measured using an R100 viscometer (manufactured by Toki Sangyo Co., Ltd.) under conditions of 25 ° C. and a cone rotation speed of 10 rpm.

[surface tension]
The surface tension was measured at 25 ° C. using a fully automatic balance type electro surface tension meter ESB-V (manufactured by Kyowa Kagaku).

[Preparation of image forming ink composition]
In a plastic bottle, the colorant, the dispersant, and the polymerizable compound (IOA and HDDA) are weighed in the amounts shown in Table 4, and 100 parts of 0.1 mm zirconia beads are added thereto, and this mixture is added to a paint conditioner ( (Toyo Seiki Co., Ltd.) for 2 hours to obtain a primary dispersion. Next, the remaining components were added to the obtained primary dispersion in the amounts shown in Table 5, and the mixture was stirred for 30 minutes with a magnetic stirrer. After stirring, this mixture was suction filtered using a glass filter (manufactured by Kiriyama Seisakusho) to prepare each image forming ink composition. The viscosity of these inks was 21.3 to 22.8 mPa · s, and the surface tension was 25.5 to 31.4 mN / m (the measurement method is the same as that for the primer ink).

[Image formation]
In the procedure described below, each primer ink was applied on each recording medium, and an image was formed thereon using each image forming ink composition to obtain a printed matter.

(1) Primer ink solid prints were respectively produced on designated media using an inkjet recording apparatus provided with a piezo-type inkjet nozzle, and a printed film having a film thickness of 5 μm was formed. This ink jet recording apparatus includes an ink tank, a supply pipe, a front chamber ink tank immediately before the head, and a piezo head as an ink supply system. Further, the ink jet recording apparatus was driven at a driving frequency of 10 KHz so that ink could be ejected with a droplet size of about 7 pl and a resolution of 600 × 600 dpi.
(2) UV LED (“NLBU21W01-E2” manufactured by Nichia Corporation) is used as the irradiating means on the printed film, and the corresponding ink is cured by irradiating with ultraviolet rays so that the total irradiation light quantity becomes 300 mJ / cm ^2. did.
(3) After forming the primer layer, using an ink jet recording apparatus equipped with a piezo ink jet nozzle, an image-forming ink solid print was prepared, and a print film having a print film thickness of 5 μm was formed. This ink jet recording apparatus includes an ink tank, a supply pipe, a front chamber ink tank immediately before the head, and a piezo head as an ink supply system. Further, the ink jet recording apparatus was driven at a driving frequency of 10 KHz so that ink could be ejected with a droplet size of about 7 pl and a resolution of 600 × 600 dpi.
(4) UV LED (“NLBU21W01-E2” manufactured by Nichia Corporation) is used as the irradiating means on the printed film, and the corresponding ink is cured by irradiating with ultraviolet rays so that the total irradiation light quantity becomes 300 mJ / cm ^2. did.

  After forming a primer layer using the primer inks of Examples 1 to 14 and Comparative Examples 1 to 6, images are formed using the image forming ink compositions of P-1 to P-5 to obtain a printed matter. It was.

  Each print was evaluated for its characteristics by the following method. The results are shown in Table 5. In addition, although the printed matter was produced about all the ink compositions for image formation shown in Table 4, the result at the time of using P-1 in which the most significant difference was recognized in the characteristic is shown as a representative.

[Adhesion]
Evaluation was performed according to “cross cut test tape (registered trademark) peeling” defined in JIS K5600-5-6. The evaluation criteria were as follows.
10 or less peeled parts in cross cut test: ○
11-20 pieces peeled off in cross section test: △
21 or more peeled parts in cross cut test: ×

[Image quality evaluation]
The formed image was visually observed, and a case where no repelling, bleeding, or color unevenness was observed was marked with ◯, and when any one was recognized, x was marked.

[Evaluation of Examples 1-14 and Comparative Examples 1-6]
As the test results in Table 5 show, it was demonstrated that the printed matter using the primer ink of the present invention can improve the image fixing property and realize a high-quality image on a non-absorbable recording medium. Although the image quality of the images formed using the primer inks of Comparative Examples 1 to 3 was good, sufficient adhesion to the recording medium was not obtained. In the image formed using the primer ink of Comparative Example 4, the surface tension of the primer ink was lower than that of the present invention, and the image forming ink was repelled. Since the primer ink of Comparative Example 5 had a surface tension higher than that of the present invention, the primer ink could not be uniformly coated on the recording medium, and color unevenness appeared in the image forming ink. Since the primer ink of Comparative Example 6 had a high viscosity, it could not be applied to a recording medium by an inkjet method. Therefore, the image on the primer could not be evaluated.
When all the primer inks were filled in an aluminum pouch coated with polyethylene on the inside and stored at 60 ° C. for 30 days, only the primer ink of Example 13 was polymerized and solidified in the aluminum pouch. . The viscosity and surface tension of the other primer inks both had a change rate in the range of ± 5% with respect to the initial values, and had excellent storage suitability.

  In addition, all the printed materials on which the glass plate, the glass epoxy, and the nylon plate were drawn only with the image forming ink without using the primer ink had a result of “x” in the adhesion test.

Claims (3)

  It contains at least one adhesion promoting component selected from the group consisting of an N-vinyl lactam compound, an acrylamide compound and an N-vinylamide compound, and 2-hydroxy-3-phenoxypropyl acrylate, and has a surface tension of 25 to 31 mN / A primer ink having a viscosity of 50 mPa · s or less.   The primer ink according to claim 1, further comprising an antigelling agent and a surface conditioner.   The primer ink according to claim 1 or 2, which is used as a primer for an image forming ink composition having a surface tension of 25 to 32 mN / m 2.