JP2014144605A - Printing sheet and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing sheet with improved adhesion between post-curing ink and a printing coating layer and improved scratch resistance and bending resistance.SOLUTION: There is provided a printing sheet to be used in UV inkjet printing, the printing sheet comprising a sheet-like base material and a printing coating layer put on one face of the base material. The printing coating layer is formed from a solvent-based coating liquid comprising a polymer, and the printing coating layer comprises an active energy ray-polymerizable functional group.

Description

The present invention relates to a printing sheet, and more particularly, to a printing sheet used for UV inkjet printing, which includes a printing coat layer for enhancing adhesion of a curable ink to a printing sheet together with a substrate.
In this specification, “sheet” includes the concept of a tape and the concept of a film.

  For example, as described in Patent Document 1, an ink having a property of being cured by irradiation with an active energy ray such as ultraviolet rays (UV ink) is printed on a printing member such as a paper sheet or a resin sheet by an inkjet printer. A technique is known in which UV ink that is ejected toward a printing sheet and adhered onto the printing side surface of the printing sheet is cured by an ultraviolet lamp, a UV-LED, or the like.

Although printing by this UV ink jet method can enjoy the advantages of the ink jet method such as simple, inexpensive, rapid, and on-demand, there is a problem that the glossiness of the obtained image is insufficient and it becomes a matte surface. Yes.
For this reason, as described in Patent Document 2, for example, the time from when the ejected UV ink droplets reach the printing side surface of the printing sheet until irradiation with ultraviolet rays or the like is increased, and printing is performed. It has been proposed to promote the wetting and spreading of ink on the printing side of a printing sheet.

  In addition, in the printing by the UV inkjet method described in Patent Document 3, an image is formed using colored inks such as yellow and magenta, and then a transparent ink is ejected, so that the smoothness or glossiness of the printed matter or high It has been proposed to improve the sense of resolution.

JP-A-2005-47261 JP 2010-42627 A JP 2012-76247 A

  However, increasing the time from ejection to curing as described above increases the time required for printing and impairs the characteristic property of UV ink jet printing such as quick drying. In addition, the use of transparent ink leads to an increase in nozzle head and an increase in ink consumption.

  On the other hand, as a printing sheet used for various printings, a sheet made of a resin material (hereinafter also referred to as “resin sheet”) has been used as a base material. Generally, when the base material of the printing sheet is made of a resin-based sheet, a printing coat layer is provided on the surface of the base material in order to improve the adhesion with ink.

  However, the present inventors have confirmed that the properties of the UV ink printed by the UV ink jet method as described above are cured on the printing side surface of the printing sheet (the ink after curing). The printed matter by UV inkjet printing has a better ink adhesion after curing than the printed matter by transfer printing such as flexographic printing, even though the printing coat layer is provided on the surface of the substrate of the printing sheet. For this reason, when the printing sheet having the ink after curing (hereinafter also referred to as “printed matter”) is rubbed, the ink or the coating layer for printing (hereinafter also referred to as “ink or the like”) containing the ink is localized. The phenomenon that the appearance or the appearance is deteriorated due to the destruction or dropping of the ink (hereinafter referred to as “scratch resistance”), or the ink when the printed material is bent, partially drops off. Elephant resulting difficulty (hereinafter, referred to as "bending resistance".) Tend like decreases relatively seen.

  An object of the present invention is to provide a new means for solving the above-described problems in UV inkjet printing.

  The present invention, which has been completed to achieve the above object, is firstly a printing sheet used for UV inkjet printing, comprising a sheet-like substrate and a coating layer for printing laminated on one surface of the substrate. The printing coat layer is formed from a solvent-based coating solution containing a polymer, and the printing coat layer includes an active energy ray polymerizable functional group. A printing sheet is provided (Invention 1).

  By making the coating liquid for forming the coating layer for printing into a solvent system, it becomes easy for the UV ink before curing to spread on the coating layer for printing. Moreover, the reaction which couple | bonds the component which has this active energy ray polymerizable functional group with UV ink etc. by irradiation with an ultraviolet-ray etc. arises by making an active energy ray polymerizable functional group contain in the coating layer for printing. For this reason, the adhesion between the ink after curing and the coating layer for printing is improved, and even when the ink-jet printing is performed, the printed matter is excellent in scratch resistance and bending resistance.

  In the above invention (Invention 1), the printing sheet having a printed image formed on the surface thereof is left in a beaker containing pure water at 23 ° C. for 24 hours, and the printing sheet taken out from the beaker is removed. After the moisture remaining on the surface is wiped off, the surface of the printing sheet on which the printed image is formed is cut based on the cross-cut method of JIS K 5600-5-6: 1999 (ISO 2409: 1992). A crosscut part having a grid size of 100 with a spacing of 1 mm and a cut line of 10 × 10 is prepared, an adhesive tape made of Nichiban's cello tape (registered trademark) is applied to the crosscut part, and the crosscut part is attached to the crosscut part. It is preferable that the number of cells remaining after peeling off the adhesive tape is 90 or more (Invention 2). When such a condition is satisfied, the obtained printed matter is particularly excellent in scratch resistance and bending resistance even when printed by the UV inkjet method.

  In the said invention (invention 1 and 2), it is preferable that the said active energy ray polymeric functional group contains a (meth) acryloyl group (invention 3). The UV ink that adheres to the printing coat layer in the use state of the printing sheet according to the above invention is often active because a functional group having an ethylenically unsaturated bond is used as a functional group having UV curability. Similarly, the energy ray polymerizable functional group is preferably a functional group having an ethylenically unsaturated bond, and more preferably a (meth) acryloyl group from the viewpoint of high reactivity.

  In the said invention (invention 1 to 3), it is preferable that at least one part of the said polymer has the said active energy ray polymeric functional group (invention 4). When the polymer has an active energy ray-polymerizable functional group, the component contained in the UV ink and the polymer are bonded by ultraviolet irradiation, so that the adhesion of the cured ink to the printing sheet is likely to increase. .

  In the said invention (invention 1 to 4), it is preferable that the said coating liquid contains the crosslinking agent which can be bridge | crosslinked with the said polymer (invention 5). When the coating liquid contains a crosslinking agent, the coating layer for printing has a crosslinked structure in which the main polymers are bonded together via the crosslinking agent. For this reason, when an external force is applied to the printing coat layer, the printing sheet is prevented from being excessively deformed, and the deformation of the printing sheet may reduce the adhesion of the cured ink to the printing sheet. Hard to occur.

  In the said invention (invention 5), it is preferable that the said coating liquid contains the component which has the reactive functional group with respect to the said active energy ray polymeric functional group and the said crosslinking agent (invention 6). When such a component is contained in the coating liquid, a printing sheet having excellent characteristics can be formed with a coating liquid having a small number of components, and has manufacturing advantages such as easy production control. .

  In the said invention (invention 5 and 6), it is preferable that the said crosslinking agent contains an isocyanate type compound (invention 7). Crosslinking with an isocyanate compound is preferable because it is easy to control the degree of the crosslinking reaction and the crosslinking formed by the crosslinking reaction hardly causes hydrolysis or thermal decomposition.

  In the said invention (invention 7), it is preferable that the said polymer contains a polyester-type resin (invention 8). The polyester-based resin may have a hydroxyl group or a carboxyl group at a terminal or a side chain, and among these, the hydroxyl group particularly easily undergoes a crosslinking reaction with an isocyanate-based compound.

  The present invention secondly provides a coating liquid for forming a coating layer for printing provided in the printing sheet according to any of the above inventions (Inventions 1 to 8) (Invention 9). By using such a coating liquid, it is possible to produce a coating layer for printing excellent in adhesion of UV ink.

  The present invention thirdly relates to a method for producing a printing sheet comprising a sheet-like substrate and a printing coat layer laminated on one surface of the substrate, the invention described above (Inventions 1 to 8). And a step of preparing a coating liquid for forming a coating layer for printing provided in the printing sheet according to any one of the above, and applying the coating liquid on one surface of the substrate to Forming a coating film on the substrate; and drying the coating film to obtain the printing sheet including the printing coat layer and the substrate as the printing coat layer. A method for producing a printing sheet is provided (Invention 10).

  By carrying out such a manufacturing method, it is possible to more stably manufacture a printing sheet having a printing coat layer that is unlikely to cause UV ink peeling.

In the printing sheet according to the present invention, since the coating liquid for forming the printing coat layer is a solvent system, the UV ink before curing is likely to spread on the surface of the printing coat layer. In addition, by including an active energy ray polymerizable functional group in the coating layer for printing, a reaction in which the component having the active energy ray polymerizable functional group is combined with the UV ink upon irradiation with ultraviolet rays or the like occurs.
Therefore, when the printing sheet according to the present invention is used, the adhesion between the cured ink and the printing coat layer is improved, and the scratch resistance and the bending resistance are improved.

Hereinafter, embodiments of the present invention will be described.
1. Printing Sheet A printing sheet according to an embodiment of the present invention includes a sheet-like base material and a printing coat layer laminated on one surface of the base material.

(1) Base material The material of the base material provided in the printing sheet according to the present embodiment is not particularly limited, and may be composed of a resin-based sheet containing a resin-based material as a main component, or a paper-based material. It may be comprised from the synthetic paper.

  Examples of the resin relating to the resin-based sheet include polyolefin resins such as polyethylene resins and polypropylene resins, polyester resins such as polybutylene terephthalate resins and polyethylene terephthalate (PET) resins, acetate resins, and acrylonitrile-butadiene-styrene copolymer (ABS) resins. , Polystyrene resin, vinyl chloride resin, polyamide resin, polyesteramide resin, polyether resin, polyimide resin, polyamideimide resin, poly-p-phenylene sulfide resin, polyetherester resin, and the like. The base material may be comprised from 1 type of these resin, and may be comprised from 2 or more types.

  As described later, when the coating liquid for forming the coating layer for printing contains a crosslinking agent, particularly a crosslinking agent containing an isocyanate compound, from the viewpoint of increasing the reactivity with the isocyanate compound, Preferably, the material is a polyester resin, polyamide resin, polyether ester resin, or the like, in which the polymer constituting the resin is formed by a condensation-type polymerization bond, and molecules generated by condensation polymerization are water and / or alcohol. It is more preferable that Among these, a polyester resin excellent in balance such as stability in market availability, low cost and quality stability is preferable.

  The base material may be composed of a single layer film containing the above-mentioned resin-based material, or a plurality of films containing the resin-based material may be laminated to form the base material. Good. Moreover, when a base material consists of a film, the film may be an unstretched thing and may be extended | stretched by uniaxial direction, such as length or width, or biaxial direction.

  Specific examples of the case where the substrate is made of a paper-based material include: glassine paper, coated paper, fine paper, dust-free paper, impregnated paper, and other paper base materials, and the above-mentioned paper base material, such as polyethylene resin Laminate paper that has been laminated.

  The base material may be colored when the material which comprises a base material contains coloring materials (a pigment and dyes, such as carbon black and titanium dioxide, are illustrated). Furthermore, the material which comprises a base material may contain microparticles | fine-particles, such as a silica, from a viewpoint of improving a mechanical characteristic or providing blocking resistance.

  Although there is no restriction | limiting in particular in the thickness of a base material, Usually, 10 micrometers or more and about 300 micrometers or less, Preferably they are 25 micrometers or more and 200 micrometers or less.

  When using a substrate made of a resin-based sheet, a surface treatment may be performed on one or both sides by an oxidation method or an unevenness method, if desired, for the purpose of improving adhesion with a layer provided on the surface. it can. Examples of the oxidation method include corona discharge treatment, chromic acid treatment (wet), flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment and the like, and examples of the unevenness method include sand blast method and solvent treatment method. Is mentioned. These surface treatment methods are appropriately selected according to the material constituting the substrate, but generally, the corona discharge treatment method is preferably used from the viewpoints of effects and operability. Moreover, primer treatment can also be performed.

(2) Coating layer for printing The coating layer for printing provided in the printing sheet according to the present embodiment is formed from a solvent-based coating solution containing a polymer as a main component, and is used for this printing. The coating layer contains an active energy ray polymerizable functional group. In a preferred example, the coating solution contains a crosslinking agent capable of crosslinking with the polymer.

(A) Polymer There are no particular limitations on the type of polymer that is the main component of the coating layer for printing. The "main agent" means a material having the largest content (mass ratio) among the materials constituting the printing coat layer, and is a component occupying 50% by mass or more with respect to the entire material. preferable. In the present specification, the “polymer” includes the concept of an oligomer.

  Specific examples of the type of polymer according to this embodiment include polyester, polyolefin, polyamide, polyurethane, polystyrene, and the like. Among these, polyester, polyamide, polyurethane, and the like are preferable from the viewpoint that it is easy to form a crosslinked structure described later. Among these, polyester will be described in some detail.

  The polyester has in its main chain an ester bond obtained by copolymerizing a polyol as a monomer and a polyvalent carboxylic acid and / or a carboxylic acid anhydride (also referred to as “carboxylic acid component” in the present embodiment). It is a polymer.

  Specific examples of the polyol include polyether polyols such as diethylene glycol, dipropylene glycol, triethylene glycol, and polyethylene glycol, polyester polyol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-pentanediol, neo Examples include pentyl glycol, 1,6-hexanediol, cyclohexanediol, 2,2,4-trimethyl-1,3-pentanediol, glycerin, glycerin monoallyl ether, trimethylolethane, trimethylolpropane, and pentaerythritol.

  On the other hand, as specific examples of the carboxylic acid component, malonic acid, phthalic acid, terephthalic acid, isophthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, succinic acid, glutaric acid, Hexachloroendomethylenetetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, endomethylenehexahydrophthalic acid, adipic acid, sebacic acid, azelaic acid, dimer acid, decadicarboxylic acid, cyclohexanedicarboxylic acid, trimellitic acid, pyromellitic acid, trimesic acid And polyvalent carboxylic acids such as cyclopentanedicarboxylic acid and anhydrides of these polyvalent carboxylic acids.

  The combination of these polyol and carboxylic acid components is not limited, and the polyester may be a polymer related to one type of combination or a polymer related to a plurality of types of combinations.

  Furthermore, the polyester may be a urethane-modified polyester. As specific examples of the urethane-modified polyester, various polyisocyanate compounds (specific examples thereof will be described later) are added to polyester polyols having a hydroxyl group at the terminal of the polymer obtained by condensation polymerization of the above-described polyol and a carboxylic acid component. It is the same as the polyisocyanate compound that can be contained in the cross-linking agent related to the cross-linked structure.) (Polyester urethane) obtained by reacting. In the present embodiment, a resin material having an ester bond in the main chain, such as polyester and urethane-modified polyester, is referred to as a polyester resin. Since the polyester resin easily reacts with an isocyanate crosslinking agent to form a crosslinked structure, the polymer according to this embodiment preferably includes a polyester resin.

  In the case where the coating liquid for forming the coating layer for printing according to this embodiment contains a crosslinking agent, the specific types of reactive functional groups that are sites that react with the crosslinking agent in the polymer are limited. Not. In the case where the crosslinking agent contains an isocyanate compound (the definition will be described later), a hydroxyl group, a carboxyl group, an amino group, and the like are listed as specific examples of the reactive functional group, and this reactive functional group is a polymerized polymer. It may be one that participates in the reaction (that is, one that participates in main chain formation) or may be provided additionally. For example, when the polymer includes a polyester-based resin, a structural unit based on polyol may have a hydroxyl group, or a structural unit based on a carboxylic acid component may have a carboxylic acid. Depending on the type of the crosslinking agent, these residual hydroxyl groups and residual carboxylic acids in the polymer may be the reactive functional groups.

  In addition, it is good also as what contains an active energy ray polymeric functional group in the coating layer for printing because at least one part of a polymer has the active energy ray polymeric functional group mentioned later. A polymer having such a structure (hereinafter also referred to as “ink-reactive polymer”) is, for example, a monomer and / or oligomer (hereinafter referred to as “single polymer”) in the stage of performing a polymerization reaction to form a polymer. In addition, a compound having an active energy ray-polymerizable functional group is allowed to coexist with the monomer, and a reaction between the compound and the monomer is generated together with a polymerization reaction of the monomer, etc. Can be produced by incorporating the compound into

(B) Crosslinking structure When the coating liquid for forming the printing coat layer according to this embodiment contains a crosslinking agent capable of crosslinking with the polymer, the printing coat layer is a polymer via a crosslinking agent. It has a cross-linked structure. Since the hardness of the printing coat layer is increased by having a crosslinked structure between the polymers, the printing coat layer may be excessively deformed or cohesive failure may occur when an external force is applied to the printing coat layer. Is suppressed. Therefore, when the coating liquid for forming the coating layer for printing contains a crosslinking agent capable of crosslinking with the polymer, the adhesion of the cured ink to the printing sheet is reduced due to deformation of the printing sheet. It becomes difficult to happen.

  The kind of the crosslinking agent that gives the above crosslinked structure is not particularly limited. Examples include epoxy compounds, isocyanate compounds, metal chelate compounds, polyimine compounds such as aziridine compounds, melamine resins, urea resins, dialdehydes, methylol polymers, metal alkoxides, and metal salts. Among these, the crosslinking agent preferably includes a polyisocyanate compound having two or more isocyanate groups per molecule, and more preferably includes a polyisocyanate compound. Cross-linking with a polyisocyanate compound makes it easy to control the degree of the cross-linking reaction, and the cross-linking formed by the cross-linking reaction hardly causes hydrolysis or thermal decomposition.

  Examples of the polyisocyanate compound include aromatic polyisocyanate compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; dicyclohexylmethane-4,4′-diisocyanate, bicycloheptane triisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, Examples thereof include alicyclic polyisocyanate compounds such as methylcyclohexylene diisocyanate and hydrogenated xylylene diisocyanate; and aliphatic polyisocyanate compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and lysine diisocyanate.

  Also, biuret bodies, isocyanurate bodies of these polyisocyanate compounds, and adduct bodies that are reaction products of these compounds with non-aromatic low-molecular active hydrogen-containing compounds such as ethylene glycol, trimethylolpropane, castor oil, etc. A modified product such as can also be used. In the present specification, the “isocyanate compound” means a general term for a polyisocyanate compound and a compound based on a polyisocyanate compound such as the biuret and modified products described above and having crosslinkability.

  The isocyanate compound contained in the cross-linking agent according to this embodiment may be one type or a plurality of types. From the viewpoint of adhesion of the UV ink, the isocyanate compound contained in the cross-linking agent according to the present embodiment preferably contains a hexamethylene diisocyanate compound, and is an isocyanurate of a hexamethylene diisocyanate compound. Is particularly preferable from the viewpoint of preventing cohesive failure in the printing coat layer.

  When a crosslinking agent is contained in the coating liquid for forming the coating layer for printing, the addition amount is preferably 1 part by mass or more as a solid content with respect to 100 parts by mass of the polymer. When the amount of the crosslinking agent is 1 part by mass or more, the hardness of the printing coat layer is moderately increased, and the cohesive failure in the printing coat layer when the UV ink provided on the printing coat layer is cured. The possibility can be reduced, and as a result, the scratch resistance and bending resistance of the printed matter can be improved. From the viewpoint of obtaining this effect more stably, the amount of the crosslinking agent is preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more. The upper limit of the amount of the cross-linking agent is not particularly limited, but if it is excessively high, there is a possibility that a disadvantage is caused from an economical point of view. Further, the printing coat layer becomes excessively hard, and the cured UV ink is rather peeled off. There may be a concern that the resistance to abrasion and the bending resistance may be reduced. Therefore, the amount of the crosslinking agent is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 20 parts by mass or less, based on 100 parts by mass of the polymer.

  When the printing coat layer has a crosslinked structure, the degree of the crosslinked structure between the polymers in the printing coat layer (in other words, the density of crosslinking points) is not particularly limited. By having an appropriate crosslinking density, it is possible to more stably realize the shape of the printing coat layer and maintain the printing quality. However, if the degree of cross-linking structure (existence density of cross-linking points) is excessively high, the difference in hardness with other components in contact with the print coat layer, particularly the base material, increases the possibility of causing interface peeling, As a result, it may be set as appropriate in consideration of the possibility that the scratch resistance and bending resistance of the printed matter may decrease.

  A gel fraction is illustrated as one method for quantitatively evaluating the degree of the crosslinked structure between polymers. In the present embodiment, the gel fraction refers to that after the curing period has elapsed, specifically, after the heat treatment of the coating film made of the coating liquid for forming the print coat layer, The gel fraction after storage for 7 days in an environment with a relative humidity of 50%. This gel fraction is preferably 50% or more. When the gel fraction is 50% or more, it is possible to improve the scratch resistance and bending resistance of the printed matter regardless of the type of the UV ink and the substrate, and the gel fraction is 60% or more. In some cases, it is possible to further improve the scratch resistance and bending resistance of the printed matter, and when the gel fraction is 70% or more, it is possible to particularly improve the scratch resistance and folding resistance of the printed matter. is there. The condition of the gel fraction is not particularly limited, but when the gel fraction is 95% or more, the scratch resistance and the bending resistance of the printed matter may tend to be lowered, so the gel fraction is 95%. It is preferable to set the degree as the upper limit.

(C) Active energy ray polymerizable functional group The active energy ray polymerizable functional group (hereinafter, also referred to as “ink reactive group”) contained in the coating layer for printing according to the present embodiment is an active energy ray, that is, an electromagnetic wave. Or a charged particle beam having an energy quantum, for example, a functional group having a binding property to other compounds by irradiation with ultraviolet rays, electron beams, etc., which is a vinyl group, (meth) acryloyl group, epoxy And functional groups including a group, an oxetane group, and an isocyanate group. In the present specification, the (meth) acryloyl group means both an acryloyl group and a methacryloyl group. The same applies to other similar terms.

  The UV ink that adheres to the printing coat layer during printing of the printing sheet according to the present embodiment often uses a functional group having an ethylenically unsaturated bond as the functional group having UV curable properties. Similarly, the reactive group is also a functional group having an ethylenically unsaturated bond, preferably a vinyl group or a (meth) acryloyl group, and a (meth) acryloyl group from the viewpoint of high reactivity. Is more preferable.

  When the ink reactive group reacts with the UV ink by UV irradiation, a compound having an ink reactive group as a partial structure contained in the coating layer for printing (hereinafter also referred to as “ink reactive component”) is chemically reacted with the cured UV ink. Join. As a result, the cured UV ink has a negative effect on the print coat due to the interaction between the ink reaction component and the other materials constituting the print coat layer, specifically the anchor effect, molecular entanglement, hydrogen bonding, etc. The adhesion is improved, and even if the UV ink contracts as it hardens, peeling at the interface between the UV ink and the printing coat layer is less likely to occur.

  Among the ink reaction components, as specific examples of components blended independently of the polymer, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di ( (Meth) acrylate, polyethylene glycol di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified diphosphate (Meth) acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid Dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, pentaerythritol tetra (meth) acrylate, dipentaerythritol Examples thereof include polyfunctional (meth) acrylates such as penta (meth) acrylate, propionic acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and caprolactone-modified dipentaerythritol hexa (meth) acrylate. From the viewpoint of facilitating the interaction with other materials constituting the printing coat layer, (meth) acrylates in which at least one hydroxyl group remains are preferred examples. As such (meth) acrylates, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol penta (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, 2-hydroxy Examples include ethyl acrylate (HEA), 2-hydroxypropyl acrylate (HPA), 4-hydroxybutyl acrylate (4-HBA), and the like. The blending amount of the ink reaction component is preferably 0.5 to 30 parts by mass, more preferably 1 to 25 parts by mass, and particularly preferably 3 to 20 parts by mass with respect to 100 parts by mass of the polymer.

  The ink reaction component may be composed of one type of compound or may be composed of a plurality of types of compounds. Further, as described above, at least a part of the polymer contained in the printing coat layer according to the present embodiment may be an ink reactive polymer. The ink reaction component may be a relatively low molecular weight compound having an ink reactive group, or may be an ink reactive polymer.

  The method for preparing the ink-reactive polymer is arbitrary. As an example, as described above, a compound having an ink reactive group is allowed to coexist in performing a polymerization reaction of a monomer or the like for forming an ink-reactive polymer. By allowing the reaction to proceed, this compound is incorporated into the polymer skeleton, and an ink-reactive polymer can be obtained. Alternatively, it can also be obtained by separately blending a low molecular weight component having an ink reactive group, an oligomer or the like with a polymer generated without the coexistence of a compound having an ink reactive group.

(D) Other content component When the coating layer for printing which concerns on this embodiment contains a crosslinking agent, it is preferable to contain a crosslinking accelerator from a viewpoint of accelerating the crosslinking reaction of a crosslinking agent. The type of crosslinking accelerator is not particularly limited, and may be set according to the type of crosslinking agent used. As an example, when a crosslinking agent contains an isocyanate type compound, the crosslinking accelerator which consists of a metal organic compound is mentioned. Here, the “metal organic compound” includes an organic metal compound having at least one metal-carbon bond and a metal organic compound having at least one metal-heteroatom bond. Specifically, for example, an organometallic compound such as dimethyltin dichloride, a fatty acid salt of an organometallic compound such as dimethyltin dilaurate, and a thioglycol of an organometallic compound such as dimethyltin bis (octylthioglycolate) salt Metal soaps such as acid ester salts and bismuth octylate are included in the concept of metal organic compounds. The metal soap refers to a metal salt other than an alkali metal salt of fatty acid (soap in a narrow sense).

  The metal contained in the metal organic compound is not particularly limited, but is preferably one or more metals selected from the group consisting of tin, zinc, lead, bismuth, titanium, vanadium, zirconium, aluminum, and nickel. . The chemical structure of the metal organic compound having the above metal is not particularly limited as long as the metal organic compound functions as a crosslinking accelerator. Specific examples of such metal organic compounds include compounds having structures such as alkoxides, carboxylates, chelates, and the like, and preferred examples include the above-mentioned metal acetylacetone complexes, acetylacetonates, octylic acid compounds, or naphthenic acid compounds. . Among these organometallic compounds, those containing bismuth are preferable because they are excellent in crosslinking promoting ability. Examples of the metal organic compound containing bismuth include bismuth 2-ethylhexylate and bismuth naphthenate.

  Although content of a crosslinking accelerator is not specifically limited, 0.001 mass% or more and 5 mass% or less are preferable in conversion of a metal amount with respect to the whole coating layer for printing, and 0.01 mass% or more and 2 mass% or less are more. 0.05 mass% or more and 1 mass% or less are especially preferable.

  In addition to the above components, the coating layer for printing according to the present embodiment includes coloring materials such as dyes and pigments, antioxidants such as anilides and phenols, ultraviolet absorbers such as benzophenone and benzotriazole, talc, You may contain filler components, such as titanium dioxide, a silica, and starch, a plasticizer, antioxidant, a light stabilizer, a dispersing agent, a leveling agent. Although content of these components is arbitrary, it is preferable that these components do not exceed 10 mass% with respect to the whole coating layer for printing.

(E) Characteristics of Printing Coat Layer A printed material obtained by curing UV ink dropped by an ink jet printing apparatus on the printing coat layer according to this embodiment has excellent scratch resistance and bending resistance. In order to impart the excellent scratch resistance and bending resistance to the printed matter, the coating layer for printing according to the present embodiment has excellent water resistance adhesion described below.

  That is, the water-resistant adhesion is obtained by immersing a printing sheet having a printed image on the surface thereof in a beaker containing pure water at 23 ° C. for 24 hours, and removing the surface of the printing sheet from the beaker. After wiping off the water remaining on the surface of the printing sheet, on the surface on which the printed image is formed, a cut interval of 1 mm, based on the cross-cut method of JIS K 5600-5-6: 1999 (ISO 2409: 1992), Create a crosscut part with 100 squares as 10 cut lines, stick an adhesive tape made of Nichiban's cello tape (registered trademark) to the crosscut part, and attach the adhesive tape attached to the crosscut part. Evaluation can be made by measuring the number of squares remaining after peeling.

  In the printing coat layer according to this embodiment, the number of grids measured based on this evaluation is preferably 90 or more. In this case, since the printing coat layer is particularly excellent in water-resistant adhesion, it is easy to obtain a printed matter particularly excellent in scratch resistance and bending resistance. The number of the above-mentioned cells is more preferably 95 or more.

(F) Thickness of the coating layer for printing Although the thickness of the coating layer for printing which concerns on this embodiment is not specifically limited, Usually, they are 30 nm or more and 1000 nm or less. If this thickness is excessively thin, there is a concern that the adhesiveness will decrease, and if it is excessively thick, secondary problems such as decreased productivity and reduced blocking resistance will occur. There is concern. The preferable thickness of the coating layer for printing is 50 nm or more and 400 nm or less.

(G) Manufacturing method of coating layer for printing The coating layer for printing which concerns on this embodiment is manufactured using the coating liquid for forming the coating layer for printing. Hereinafter, after describing the above-described coating liquid, a method for producing a coating layer for printing using the coating liquid will be described.

(I) Coating liquid for forming the coating layer for printing In one specific example, the coating liquid for forming the coating layer for printing according to the present embodiment includes a polymer as a main component of the coating layer for printing and It contains an ink reaction component together with a solvent-based solvent, and further contains other components such as a crosslinking agent and a crosslinking accelerator used as necessary. Hereinafter, this coating solution is also referred to as “first coating solution”. In preparing the first coating liquid, a mixture is prepared by previously mixing these components so that the interaction between the polymer and the ink reaction component is facilitated. Other components may be mixed.

  In the present specification, the “solvent solvent” is a solvent containing at least one organic compound and is liquid in an environment of use (specifically, an environment of 23 ° C., relative humidity 50%, 1 atm). The thing in the state of. The organic compound that constitutes the solvent-based solvent may consist of a compound that is in a liquid state in the environment of use alone, or an organic compound that is in a liquid state in the environment of use when combined alone but in a solid state It may consist of The solvent-based solvent may contain water within 10% by mass of the total amount of the solvent as long as it does not affect the characteristics.

  The specific composition of the solvent-based solvent used in the first coating liquid is particularly limited as long as it can disperse or dissolve the polymer and the ink reaction component as the main components of the coating layer for printing, and can be removed by drying after coating. It is not limited. Specific examples of solvent solvents include ester solvents such as ethyl acetate and butyl acetate, ketone solvents such as methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone, and aromatic hydrocarbon solvents such as toluene and xylene. .

  The coating liquid for forming the printing coat layer according to the present embodiment is a solvent-based coating liquid containing a solvent-based solvent, and thus the printing coat layer generated from the coating liquid is Its surface becomes lipophilic. Here, since the UV ink has an active energy ray-polymerizable functional group such as a (meth) acryloyl group, it is generally lipophilic. For this reason, when the surface of the printing coat layer is oleophilic, the UV ink tends to wet and spread on the surface, and the contact angle of the UV ink with respect to the printing coat layer tends to be small. For this reason, when the UV ink is cured by ultraviolet rays or the like, the ratio of the contact area with the printing coat layer to the volume of the cured ink is high, and the cured ink is difficult to peel off from the printing coat layer.

For comparison, when the solvent of the coating solution for forming the coating layer for printing is aqueous, the polymer dissolved or dispersed in the solvent has a large number of hydrophilic functional groups. Become. For this reason, the coating layer for printing formed from such a coating liquid has many hydrophilic functional groups on the surface thereof. Therefore, the lipophilic UV ink hardly spreads on the surface of the printing coat layer, and the contact angle of the UV ink with respect to the printing coat layer tends to increase. When such UV ink is cured, there is also the effect of curing shrinkage, and the ratio of the contact area with the coating layer for printing to the volume of the ink after curing decreases.
In particular, in the case of an emulsion-based coating liquid, since it contains a surfactant, the coating layer is inferior in terms of water resistance.

  In addition, since the active energy ray-polymerizable functional group is lipophilic as described above, when the solvent of the coating liquid is a solvent system like the first coating liquid, compared to the aqueous solvent, In general, a component containing an active energy ray-polymerizable functional group that is lipophilic is easily dissolved in a coating solution. For this reason, the solvent-based coating liquid can contain more ink reaction components having an active energy ray-polymerizable functional group as an ink reactive group than the water-based coating liquid. Therefore, a large number of ink reactive groups are likely to be present in a printing coat layer formed from such a solvent-based coating solution, compared to a printing coat layer formed from a water-based coating solution. When a large number of ink reaction components are present in the coating layer for printing, a reaction in which the ink reaction group of the ink reaction component and the component of the UV ink are more likely to occur. That this binding reaction is likely to occur means that the adhesiveness per unit area on the contact surface of the cured ink with the coating layer for printing is high.

  As described above, the printing coat layer formed from the first coating liquid, which is a solvent-based coating liquid, has a cured ink as compared with the printing coat formed from a water-based coating liquid. The ratio of the contact area with the printing coat layer to the volume of the ink is high, and the adhesiveness per unit area on the contact surface of the cured ink with the printing coat layer is also high. Therefore, the ink after curing on the printing coat layer formed from the first coating liquid is difficult to peel off from the printing coat layer when colliding with foreign matter (that is, excellent in scratch resistance), and the printed matter is bent. It is difficult to peel off from the coating layer for printing (that is, it is excellent in bending resistance).

  In particular, when the printing method is an inkjet method, the UV ink is often solventless so that the property of quick drying can be sufficiently exhibited. When the UV ink is solvent-free, the UV ink mainly contains a coloring component and a monomer having an active energy ray-polymerizable functional group, and thus the UV ink tends to be particularly oleophilic. Moreover, in order to be able to demonstrate the quick drying characteristics of the ink jet method, in an ink jet type printing apparatus, the time from when the ink droplet reaches the printing coat layer until the curing ultraviolet ray is irradiated is usually short. Set to For this reason, the time during which the ink droplets reaching the printing coat layer can spread and spread on the surface of the printing coat layer is also short. Therefore, when a large number of hydrophilic groups are present on the surface of the printing coat layer, such as those formed from aqueous coating liquids, it is possible to ensure a sufficient contact area between the ink droplets and the printing coat. In many cases, the ink was cured without being able to do so. In that case, the ink after curing in the ink jet printing has lower adhesion to the coating layer for printing than the ink after curing in the printing other than the printing method.

  On the other hand, since the coating layer for printing according to the present embodiment is formed from a solvent-based coating solution, the surface thereof is oleophilic. Therefore, the ink droplets attached to the printing coat layer tend to wet and spread on the surface in a short time, and as a result, the adhesion of the cured ink to the printing coat layer tends to increase. Therefore, the printing sheet according to the present embodiment can impart excellent scratch resistance and bending resistance to the printed matter even when UV inkjet printing is performed. Note that, as described above, in the printing coat layer according to this embodiment, the attached ink droplets tend to wet and spread on the surface of the printing coat layer, and thus the cured ink hardly retains the shape based on the ink droplets. Therefore, unevenness based on the shape of the ink droplet is unlikely to occur on the surface made of the cured ink. Such surface properties of the ink after curing are expected to contribute to increasing the glossiness of an image formed by the ink after curing.

  As another specific example of the coating liquid for forming the coating layer for printing according to the present embodiment, containing a polymer having an ink reactive group (active energy ray polymerizable functional group) together with a solvent-based solvent, Furthermore, the coating liquid containing other components, such as a crosslinking agent used as needed, a crosslinking accelerator, is mentioned. Hereinafter, this coating solution is also referred to as a “second coating solution”. Also in the case of this second coating liquid, since the solvent is solvent-based as in the case of the first coating liquid, it is superior in scratch resistance and bending resistance to the printed matter obtained compared to the aqueous coating liquid. Sex can be imparted.

  The method for producing the polymer having an ink reactive group in preparing the second coating liquid is not particularly limited. As an example of the production method, a compound having an ink reactive group is obtained by conducting a polymerization reaction in a state where a monomer and / or oligomer of a polymer having an ink reactive group and a compound having an ink reactive group coexist. Can be incorporated into the skeleton of the polymer. According to this method, the number of ink reactive groups (units / g) of the obtained polymer per unit mass can be easily estimated, and the degree of interaction between the printing coat layer and the UV ink can be estimated. It becomes easy. In addition, since the polymer obtained by this method contains an oleophilic ink reactive group, the affinity of the entire polymer for water tends to decrease. In such a polymer, when the solvent (dispersion medium) is aqueous, it is difficult to increase the content (dissolution amount and / or dispersion amount) in the coating liquid, and the film thickness of the coating layer for printing is controlled. This results in problems such as reduced productivity and reduced productivity due to the need for overcoating.

  The solid content concentration in the coating liquid for forming the coating layer for printing according to the present embodiment is the same for both the case of the composition of the first coating liquid and the case of the second coating liquid. The concentration is not particularly limited as long as it can be processed, but is usually about 1% by mass to 10% by mass, preferably 2% by mass to 5% by mass.

(Ii) Method for Producing Printing Coat Layer Using Coating Liquid The details of the method for producing a coating layer using the coating liquid according to the above embodiment are not particularly limited. An example is as follows. A coating liquid for forming a printing coat layer is prepared, and the coating liquid is applied to one surface of the substrate by, for example, a gravure roll method, an air knife method, a wire bar coating method, or the like. A coating layer for printing is formed by drying a coating film made of this coating solution. The drying conditions are not particularly limited, and the drying conditions may be left in a normal environment (for example, 23 ° C., relative humidity 50%) to dry, or the coating film may be heated. When heating a coating film, the specific conditions are not specifically limited, What is necessary is just to set conditions suitably according to the characteristic of the solvent contained in a coating liquid. As an example, it may be present in an environment of 80 to 120 ° C. for about 1 minute. When the coating solution contains a crosslinking agent, it is preferable to heat the coating film when it is dried. When the coating solution contains a crosslinking agent, for example, in an environment of 23 ° C. and 50% relative humidity in order to sufficiently advance the crosslinking reaction between the polymer and the crosslinking agent generated in the coating layer for printing. Curing is preferred. The curing period is not particularly limited, but is usually about one week in many cases.

(3) Other components The printing sheet which concerns on this embodiment may be equipped with components other than said base material and the coating layer for printing. As such a component, a pressure-sensitive adhesive layer formed on the surface of the substrate opposite to the side on which the printing coat layer is formed is exemplified. By forming such an adhesive layer, the printing sheet according to the present embodiment can be used as a printing adhesive sheet.

  Although it does not specifically limit as an adhesive used for an adhesive layer, Well-known adhesives, such as an acrylic adhesive, a polyester adhesive, a rubber adhesive, and a silicone adhesive, can be used.

  The pressure-sensitive adhesive layer may be provided by applying a coating liquid for forming the pressure-sensitive adhesive layer on the surface opposite to the surface having the coating layer for printing of the substrate, or the release surface of the release material The above coating solution is applied to form a pressure-sensitive adhesive layer, and this pressure-sensitive adhesive layer is bonded to the surface opposite to the printing coat layer side of the substrate to form a pressure-sensitive adhesive layer with a release material May be.

  The method for forming the pressure-sensitive adhesive layer is not particularly limited, and an ordinary method can be used. For example, the pressure-sensitive adhesive layer can be formed by a gravure roll method, a roll knife method, or the like.

  In the present invention, the thickness of the pressure-sensitive adhesive layer is not particularly limited, but is usually in the range of 5 μm to 100 μm, and preferably in the range of 10 μm to 50 μm.

  The surface of the pressure-sensitive adhesive layer on the side opposite to the substrate side may be exposed. Usually, however, a release material is temporarily attached to protect the pressure-sensitive adhesive layer until it is used.

  The release material comprises a release surface having a sheet-like support substrate and at least one surface having releasability. This release surface may be the surface opposite to the support substrate side of the release agent layer provided on the surface of the support substrate that does not have peelability, or the surface of the support substrate that has peelability. It may be.

  Examples of the support material for the release material include paper, synthetic paper, and resin film. Examples of the paper include glassine paper and polyethylene laminated paper. Examples of the resin film include polyolefin resins such as polyethylene resin and polypropylene resin, polyester resins such as polybutylene terephthalate resin and polyethylene terephthalate resin, acetate resin, polystyrene. Examples thereof include a resin film and a vinyl chloride resin film. Examples of the release treatment agent constituting the release agent layer include silicone resins, alkyd resins, fluororesins, and long-chain alkyl-containing resins. Examples of the support substrate having a peelable surface include polyolefin resin films such as polypropylene resin films and polyethylene resin films, and films obtained by laminating these polyolefin resin films on paper or other films.

  Although the thickness of the support base material of the release material is not particularly limited, it may be usually about 15 μm or more and 300 μm or less.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
As the polymer, 50 parts by mass of urethane-modified polyester resin (Toyobo Co., Ltd., Byron UR1400, solid content: 30%, solvent type) and urethane-modified polyester resin (Toyobo Co., Ltd., Byron UR3200, solid content: 100%) 50 1.5 parts by mass of pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK Ester A-TMM-3L, solid content 100%) as a component having an active energy ray polymerizable functional group, hexamethylene diisocyanate as a crosslinking agent -Based cross-linking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HL, solid content 75%), and bismuth-based metal organic compound (manufactured by Nippon Kagaku Sangyo Co., Ltd., PACCAT 25, metal content 25% by mass) as a crosslinking accelerator 0 Mix 5 parts by mass and dilute with toluene to prepare a 1.5% solids coating solution. It was.

  On one surface of a biaxially stretched polyethylene terephthalate (PET) film (Toray Co., Ltd., Lumirror PET50T-60) having a thickness of 50 μm as a substrate, the film thickness after drying the above coating solution by bar coating is 100 nm. And dried at 90 ° C. for 1 minute. The dried printing sheet was further cured for 7 days under the conditions of 23 ° C. and relative humidity of 50% to obtain a printing sheet as an evaluation object. In addition, the film thickness after drying was measured with a spectroscopic ellipsometer (manufactured by JA Woollan, M-2000).

[Example 2]
In the preparation of the coating solution, a coating solution was obtained in the same manner as in Example 1 except that the amount of coronate HL was 15 parts by mass. Hereinafter, the same operation as in Example 1 was performed to obtain a printing sheet including a printing coat layer having a film thickness of 100 nm.

Example 3
In the preparation of the coating liquid, a coating liquid was obtained in the same manner as in Example 1 except that the amount of NK ester A-TMM-3L used was 6 parts by mass. Hereinafter, the same operation as in Example 1 was performed to obtain a printing sheet including a printing coat layer having a film thickness of 100 nm.

Example 4
In preparation of the coating liquid, 1.5 parts by mass of pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK Ester A-TMMT, solid content 100%) is used as a component having an active energy ray polymerizable functional group, and Coronate HL. A coating solution was obtained in the same manner as in Example 1 except that the amount used was 10 parts by mass. Hereinafter, the same operation as in Example 1 was performed to obtain a printing sheet including a printing coat layer having a film thickness of 100 nm.

Example 5
In preparation of the coating liquid, 1.5 parts by mass of dipentaerythritol pentaacrylate (manufactured by Sartomer, SR399E, solid content 100%) is used as a component having an active energy ray polymerizable functional group, and the amount of coronate HL used is 10 A coating solution was obtained in the same manner as in Example 1 except that the content was changed to parts by mass. Hereinafter, the same operation as in Example 1 was performed to obtain a printing sheet including a printing coat layer having a film thickness of 100 nm.

Example 6
In the preparation of the coating solution, 1.5 parts by mass of dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-DPH, solid content 100%) is used as a component having an active energy ray polymerizable functional group, and coronate. A coating solution was obtained in the same manner as in Example 1 except that the amount of HL used was 10 parts by mass. Hereinafter, the same operation as in Example 1 was performed to obtain a printing sheet including a printing coat layer having a film thickness of 100 nm.

Example 7
In the preparation of the coating solution, a coating solution was obtained in the same manner as in Example 1 except that the coronate HL was not added. Hereinafter, the same operation as in Example 1 was performed to obtain a printing sheet including a printing coat layer having a film thickness of 100 nm.

[Comparative Example 1]
In the preparation of the coating solution, a coating solution was obtained in the same manner as in Example 1 except that the active energy ray polymerizable functional group and the crosslinking agent were not blended. Hereinafter, the same operation as in Example 1 was performed to obtain a printing sheet including a printing coat layer having a film thickness of 100 nm.

[Comparative Example 2]
As a polymer, 100 parts by mass of water-dispersed polyester resin (manufactured by Toyobo Co., Ltd., Vironal MD-1100, solid content: 30%, aqueous), polyethylene glycol diacrylate (manufactured by Sartomer, SR344, solid content) as an active energy ray polymerizable functional group 100%) was mixed with 7 parts by mass and diluted with a mixed solvent of water and isopropyl alcohol (water 40% by mass, isopropyl alcohol 60% by mass) to obtain a coating liquid having a solid content of 1.5% by mass. Hereinafter, the same operation as in Example 1 was performed to obtain a printing sheet including a printing coat layer having a film thickness of 100 nm.

[Test Example 1] <Evaluation of peel resistance of UV ink>
(Printing conditions)
For each of the printing sheets obtained in the examples and comparative examples, a UV ink jet printer (manufactured by Roland DG, LEC-300A) using UV ink (manufactured by Roland DG, ECO-UV ink) on the surface of the coating layer for printing. ) To obtain a printed image.

(Adhesion evaluation)
Each of the printing sheets on which printed images were formed by performing the above printing was allowed to stand for 24 hours in an environment of 23 ° C. and relative humidity of 50%. After that, on the surface of the printing sheet on which the printed image is formed, on the side where the printed image is formed, based on the cross-cut method of JIS K 5600-5-6: 1999 (ISO 2409: 1992), the cut interval is 1 mm, and the cut A cross cut portion having a grid number of 100 was prepared as 10 lines × 10 lines, and the adhesion between the ink and the printing sheet was evaluated. A cello tape (registered trademark) manufactured by Nichiban Co., Ltd. was affixed to the cross-cut portion, and the residual rate was expressed as x / 100, where x was the number of squares remaining after the tape was peeled off. An x / 100 value of 90/100 or higher was considered acceptable. The evaluation results are shown in Table 1.

[Test Example 2] <Water resistance adhesion evaluation of UV ink>
By performing printing under the same printing conditions as in Test Example 1, a printing sheet on which a printed image was formed was obtained. Each printing sheet was immersed in a beaker containing pure water at 23 ° C. for 24 hours. Based on the cross-cut method of JIS K 5600-5-6: 1999 (ISO 2409: 1992) on the surface on which the printed image is formed on each printing sheet after immersion, a cut interval of 1 mm and 10 cut lines × A cross cut part having a grid size of 100 was prepared as 10 and the water-resistant adhesion between the ink and the printing sheet was evaluated. A cello tape (registered trademark) manufactured by Nichiban Co., Ltd. was affixed to the cross-cut portion, and the residual rate was expressed as x / 100, where x was the number of squares remaining after the tape was peeled off. An x / 100 value of 90/100 or higher was considered acceptable. The evaluation results are shown in Table 1.

[Test Example 3] <Evaluation of scratch resistance>
By performing printing under the same printing conditions as in Test Example 1, a printing sheet on which a printed image was formed was obtained. For each printing sheet, the end of a coin (500 yen coin) was applied to the printing surface of the printing sheet, and the printing surface was strongly reciprocated 10 times, and evaluated according to the following criteria. The evaluation results are shown in Table 1.
A: No change in the printing surface is confirmed.
B: A slight rubbing trace was confirmed on the printed surface.
C: Printing was peeled off and the base film was visible.

[Test Example 4] <Bending resistance evaluation>
Each of the printing sheets obtained in Examples and Comparative Examples was cut into a size of 10 cm × 10 cm to obtain a test piece. Each test piece was bent so that the printing surfaces were in contact with each other, and then the same portion was bent so that the surfaces opposite to the printing surface of the test piece were in contact with each other. After repeating this operation five times, the presence or absence of peeling of printing at the crease portion was evaluated. The evaluation results are shown in Table 1.
A: No peeling is confirmed.
B: Some peeling was confirmed.
C: Printing was peeled off and the base film was visible.

  In the printing sheet of the present invention, since the ink formed by curing the UV ink attached to the printing coating layer of the sheet is difficult to peel off from the printing sheet layer, the printed matter obtained even if the printing method is an inkjet method Is excellent in scratch resistance and bending resistance. Therefore, the printing sheet of the present invention can be suitably used for UV inkjet printing.

Claims (10)

A printing sheet used for UV inkjet printing comprising a sheet-like substrate and a printing coat layer laminated on one surface of the substrate,
The coating layer for printing is formed from a solvent-based coating solution containing a polymer,
The printing sheet is characterized in that the coating layer for printing contains an active energy ray polymerizable functional group.   The printing sheet on which the printed image was formed was left in a beaker containing pure water at 23 ° C. for 24 hours, and water remaining on the surface of the printing sheet taken out from the beaker was wiped off. Thereafter, on the surface of the printing sheet on which the printed image is formed, a cut interval of 1 mm and 10 cut lines based on the cross-cut method of JIS K 5600-5-6: 1999 (ISO 2409: 1992) × A crosscut part having a grid size of 100 is produced as ten pieces, an adhesive tape made of Nichiban's cello tape (registered trademark) is applied to the crosscut part, and the adhesive tape attached to the crosscut part is pulled. The printing sheet according to claim 1, wherein the number of grids remaining after the peeling is 90 or more.   The printing sheet according to claim 1, wherein the active energy ray polymerizable functional group includes a (meth) acryloyl group.   The printing sheet according to any one of claims 1 to 3, wherein at least a part of the polymer has the active energy ray polymerizable functional group.   The printing sheet according to any one of claims 1 to 4, wherein the coating liquid contains a crosslinking agent capable of crosslinking with the polymer.   The printing sheet according to claim 5, wherein the coating liquid includes a component having a reactive functional group with respect to the active energy ray polymerizable functional group and the crosslinking agent.   The printing sheet according to claim 5 or 6, wherein the crosslinking agent contains an isocyanate compound.   The printing sheet according to claim 7, wherein the polymer includes a polyester-based resin.   The coating liquid for forming the coating layer for printing with which the printing sheet as described in any one of Claim 1 to 8 is provided. A method for producing a printing sheet comprising a sheet-like substrate and a printing coat layer laminated on one surface of the substrate,
A step of preparing a coating liquid for forming a printing coat layer included in the printing sheet according to any one of claims 1 to 8, and the coating liquid on one surface of the substrate A step of forming a liquid layer of a coating liquid on the substrate by applying to the substrate, and drying the liquid layer as the coating layer for printing, the printing layer comprising the coating layer for printing and the substrate And a step of obtaining the sheet.