JP2014051075A - Printing sheet and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing sheet from which UV ink does not easily peel off upon curing, a coating material to form a coating layer for printing which the printing sheet comprises, and a method for producing the printing sheet using the coating material.SOLUTION: A printing sheet comprises: a sheet-like substrate; an anchor layer laminated on a surface of one side of the substrate; and a coating layer for printing laminated on a surface of the anchor layer on the opposite side to that facing the substrate. In the printing sheet, the anchor layer satisfies at least one of the following two properties: (property 1) an elongation at break is 200% or more and 500% or less and a strength at break is 20 MPa or less; and (property 2) an elongation at break is 200% or more and 500% or less and a ratio of the strength at break to the elongation at break is 0.05 MPa/% or less. The anchor layer preferably comprises a resin-based material and the resin-based material preferably comprises crosslinked structure formed through a reaction between a crosslinking agent and crosslinkable polymer.

Description

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

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

  On the other hand, in recent years, the demand for flexographic printing is increasing in the printing industry, and UV (ultraviolet curable) ink is the mainstream as the ink for flexographic printing. However, in flexographic printing, more reactive diluent is added so that the viscosity of the ink is lower than in normal offset printing or the like. For this reason, when flexographic printing is performed using UV ink, there is a problem that the degree of curing shrinkage of the ink is large, and the ink after curing tends to fall off from the base material of the printing sheet. Accordingly, there has been a demand for a printing sheet that can follow the shrinkage of the UV ink even when flexographic printing is performed using the UV ink and has excellent adhesion to the UV ink.

  In this regard, Patent Document 1 discloses a printable film having excellent characteristics required for a printable film, in particular, having excellent adhesion to a radiation curable ink (such as UV ink). In order to provide a printable polymer film, the objective is to have a substrate and at least one surface layer, the surface layer covering at least one surface of the substrate, and 10 to 98% water dispersible polymer; A printable film comprising 2 to 90% of an ethylenically unsaturated compound selected from a polyfunctional acrylate obtained by esterification of a polyol and (meth) acrylic acid, or a polyallyl derivative, to the surface layer When applying radiation curable ink followed by radiation to cure the ink, the ethylenically unsaturated compound is It was configured to react with the unsaturated compound of the radiation curable ink to form a chemical bond between the ethylenically unsaturated compound and the unsaturated compound of the radiation curable ink, and at the same time to crosslink the surface layer. A printable film is disclosed.

Japanese Patent No. 4027977

  By the way, the material of the base material of the printing sheet is a resin-based sheet made of a polyolefin-based resin represented by a biaxially oriented polypropylene (OPP) film from the viewpoint of production stability, cost, and mechanical properties (particularly flexibility). It may become mainstream in the future. In this case, the polarity of the surface portion of the substrate is lower than that of a resin-based sheet made of a polyester resin, which is a general resin-based sheet used as a material for the substrate. There exists a tendency for the adhesive force with respect to the base material of the coating layer for printing formed in this to fall. On the other hand, as described above, the UV ink used in the flexographic printing method, which is considered to become the mainstream in the future, has a large amount of shrinkage during UV curing. Therefore, even when such a low-polarity substrate and UV ink are used, there is a possibility that a printing sheet in which the printing coat layer is difficult to peel from the substrate after curing may be required.

  According to the technique disclosed in the above Patent Document 1, the surface layer of the film according to the above Patent Document 1 (in this specification, for the purpose of suppressing the peeling of the ink from the base material as in this surface layer). A layer that is laminated on a substrate and whose surface opposite the substrate is the surface that should be in contact with the ink is called "printing coating layer") and the possibility of separation between the ink and the ink. Although reduced, the shrinkage force accompanying the curing of the ink is transmitted to the coating layer for printing, and the printing coating layer on which the ink is laminated may peel from the substrate.

  Regarding such problems, Patent Document 1 discloses that it is preferable to provide a primer (undercoat layer) between the printing coat layer and the substrate. However, the detailed content of this primer is not disclosed in Patent Document 1, and only teaches to dispose a layer made of a material capable of improving the adhesion between the substrate and the coating layer for printing. Absent. Therefore, when the coating layer for printing to which the ink after curing adheres is particularly easily peeled off from the substrate, such as flexographic printing on the OPP film substrate, what kind of layer is used between the substrate and the coating layer for printing. It is not yet clear whether it is appropriate to place them in between.

  In the present specification, a layer that is disposed between the printing coat layer and the substrate and prevents the printing coat layer from peeling off from the substrate, the main surface of the layer (the thickness of the layer) A layer made of a material capable of measuring mechanical properties when an external force is applied in the in-plane direction of a surface having a normal line parallel to the vertical direction is called an anchor layer.

  Against this background, the present invention is a printing sheet on which the cured printing sheet is difficult to peel off from the substrate, and a coating material for forming a printing coating layer provided in the printing sheet, Another object is to provide a method for producing a printing sheet using the coating material.

  When the present inventors examined in order to achieve the above-mentioned object, by appropriately controlling the relationship between the breaking strength and breaking elongation of the anchor layer, the anchor layer breaks between the anchor layer and the base material. A new finding was obtained that the possibility of occurrence of peeling could be stably reduced.

  The present invention completed on the basis of such knowledge, firstly, a sheet-like base material, an anchor layer laminated on one surface of the base material, and a side opposite to the side of the anchor layer facing the base material A printing sheet provided with a coating layer for printing laminated on the surface, wherein the anchor layer has a breaking elongation of 200% to 500% and a breaking strength of 20 MPa or less. A sheet is provided (Invention 1).

  When the anchor layer satisfies the above conditions, the anchor layer breaks even if the ink shrinkage force generated by the ink curing is transmitted as a compressive force or tensile force to the anchor layer via the printing coat layer. When the strength is 20 MPa or less and the breaking elongation is 200% or more, such applied external force can be absorbed and relaxed as deformation of the anchor layer. In addition, since the breaking elongation of the anchor layer is 500% or less, problems such as blocking are unlikely to occur when a roll formed by winding up a laminate composed of the base material and the anchor layer is fed out.

  In addition, the present invention secondly, a sheet-like base material, an anchor layer laminated on one surface of the base material, and a printing layer laminated on a surface of the anchor layer opposite to the base material side. A printing sheet provided with a coating layer, wherein the anchor layer has a breaking elongation of 200% to 500% and a ratio of breaking strength to breaking elongation (unit: MPa /%) is 0.05 or less. There is provided a printing sheet characterized in that (Invention 2).

  When the anchor layer satisfies the above conditions, the anchor layer breaks even if the ink shrinkage force generated by the ink curing is transmitted as a compressive force or tensile force to the anchor layer via the printing coat layer. When the strength is 20 MPa or less, the breaking elongation is 200% or more and 500% or less, and the ratio of the breaking strength to the breaking elongation, such applied external force is absorbed and relaxed as an internal deformation of the anchor layer. be able to. In addition, since the breaking elongation of the anchor layer is 500% or less, problems such as blocking are unlikely to occur when a roll formed by winding up a laminate composed of the base material and the anchor layer is fed out.

  In the above invention (Invention 2), the anchor layer preferably has a breaking strength of 20 MPa or less (Invention 3). In this case, the external force applied to the anchor layer can be collected and relaxed more efficiently.

  In the above inventions (Inventions 1 to 3), the anchor layer preferably contains a resin-based material, and the resin-based material preferably includes a crosslinked structure formed by a reaction between a crosslinking agent and a crosslinkable polymer (Invention). 4). By adjusting the density of the crosslinked structure existing in the anchor layer, the mechanical properties of the anchor layer defined in the invention (Inventions 1 to 3) can be easily controlled.

  In the above invention (invention 4), the anchor layer adjusts the density of the cross-linked structure present in the anchor layer, thereby adjusting the breaking elongation and breaking strength of the anchor layer (invention 1 or 2). ) Is preferably set within the range specified in (Invention 5). Since there are many kinds of specific methods for adjusting the crosslinking density, the adjustment is easy.

  In said invention (invention 4 and 5), it is preferable that the said crosslinkable polymer contains a urethane type polymer (invention 6). When a urethane polymer is used, it becomes easy to control the mechanical properties of the anchor layer within the above range.

  In said invention (invention 4 to 6), it is preferable that the said crosslinking agent contains an epoxy-type crosslinking agent (invention 7). When the crosslinking agent includes an epoxy-based crosslinking agent, the anchor layer forming coating material that is a coating material for forming the anchor layer is aqueous (that is, the solvent and / or the dispersion medium is aqueous). Even in such a case, when the pot life is long and the crosslinking agent is composed of an epoxy-based crosslinking agent, a longer pot life coating material can be obtained.

  In said invention (invention 1 to 7), it is preferable that the said base material contains an olefin resin (invention 8). The olefin resin film is excellent in production stability, cost, and mechanical properties (particularly flexibility). In the case where the olefin resin film is a biaxially stretched propylene film (OPP), the balance between these properties is excellent, which is particularly preferable. Even if such an olefin-based resin film is a base material, the printing sheet according to the above inventions (Inventions 1 to 7) includes an anchor layer having appropriate mechanical properties. The layer is difficult to peel off.

  3rdly, this invention provides the coating material for forming the anchor layer with which the printing sheet which concerns on either of said invention (invention 1-8) is equipped (invention 9). By using such a coating material, it becomes easy to manufacture the anchor layer.

  Fourthly, the present invention relates to a method for producing a printing sheet according to any one of the above inventions (Inventions 1 to 8), for forming an anchor layer comprising the coating material according to the above invention (Invention 9). A step of applying a coating material on one surface of the substrate to form a coating film of the anchor layer forming coating material on the substrate; and a coating film of the anchor layer forming coating material Drying the substrate to obtain a laminate in which the anchor layer is laminated on the base material, and applying the printing coat layer forming material on the surface of the laminate on the anchor layer side to coat the printing A step of forming a coating film of a layer forming material on the anchor layer, and a coating film of the coating layer forming material for drying were dried, and the substrate, the anchor layer, and the printing coating layer were provided. And a step of obtaining the printing sheet. A method (invention 10).

  According to this manufacturing method, it is possible to manufacture the printing sheet according to any of the above inventions (Inventions 1 to 8) with high productivity.

  In the printing sheet according to the present invention, the relationship between the breaking strength and the breaking elongation of the anchor layer is appropriately controlled, so that the breaking inside the anchor layer and the peeling between the anchor layer and the substrate may occur. Is reduced. Therefore, if flexographic printing or the like is performed using the printing sheet according to the present invention, the problem that the printing coat layer to which the cured ink has adhered peels off from the substrate is less likely to occur. Moreover, according to this invention, the coating material for forming the anchor layer with which the printing sheet which has such an outstanding characteristic is provided, and the manufacturing method of the printing sheet using the coating material are also provided.

It is the graph which plotted the result of the Example and the comparative example by making a fracture strength into a vertical axis | shaft and breaking elongation into a horizontal axis.

Hereinafter, embodiments of the present invention will be described.
1. Printing Sheet According to one embodiment of the present invention, a printing sheet includes a sheet-like base material, an anchor layer laminated on one surface of the base material, and a surface opposite to the side facing the base material in the anchor layer. And a coating layer for printing laminated thereon.

(1) Base Material The material constituting the sheet-like base material included 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. Further, it may be made of a paper-based material.

  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. One type or a plurality of types of resins may be used for the resin-based sheet constituting the substrate.

  The base material may be constituted by a single layer film containing the above-mentioned resin-based material, or a plurality of films containing the resin-based material are laminated to constitute the base material. Also 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 base material is composed of a paper-based material include paper base materials such as glassine paper, coated paper, and high-quality paper, and laminated paper obtained by laminating a thermoplastic resin such as polyethylene to the paper base material. Can be mentioned.

  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.

  As described above, in recent years, polyolefin resins based on polyolefin resins have been increasingly used as the main component of materials constituting the substrate from the viewpoint of production stability, cost, and characteristics (particularly flexibility). ing. Specific examples of such resins include polyethylene and polypropylene. As described above, biaxially stretched polypropylene (that is, OPP) is attracting attention from the viewpoint of characteristics such as production stability, cost, and flexibility. However, since the polyolefin resin material has low resin polarity, the adhesion between the printing coat layer formed on one surface of the substrate and the substrate is also low. Even in such a case, in the printing sheet according to the present embodiment, since the anchor layer has characteristics described later, the printing coating layer is hardly peeled off from the base material.

  Although there is no restriction | limiting in particular in the thickness of a base material, Usually, they are about 15 micrometers or more and 300 micrometers or less, Preferably they are 20 micrometers or more and 200 micrometers or less.

  In the case of using a substrate made of a resin-based sheet, an oxidation method or a concavo-convex method on one side or both sides as desired for the purpose of improving the adhesion with a layer (for example, an anchor layer described later) laminated on the surface. Surface treatment can be performed by such as.

  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.

(2) Anchor layer The printing sheet according to the present embodiment includes an anchor layer provided between the base material and the printing coat layer. The anchor layer according to the present embodiment has at least one of mechanical characteristics 1 and 2 described below.
(Mechanical characteristics 1)
The breaking elongation of the anchor layer is 200% or more and 500% or less, and the breaking strength thereof is 20 MPa or less.

  Here, the measurement of the breaking elongation and the breaking strength is performed as a single anchor layer without a base material or the like. Specifically, a layered body composed of an anchor layer having a thickness of 20 μm, a width of 15 mm, and a length of 140 mm is prepared as a sample for measuring mechanical properties, and the sample for measuring mechanical properties is an environment having a temperature of 23 ° C. and a relative humidity of 50%. The sample was stretched at a speed of 200 mm / min with a tensile tester at a chuck distance of 100 mm, and the elongation and tensile force when the sample broke were measured. The breaking strength.

  When the shrinkage force of the ink generated as the ink is cured is transmitted to the printing coat layer, the force brings a compressive force or tensile force in the main surface direction of the printing coat layer. Sometimes transmitted to the layer. Even in such a case, when the breaking elongation of the anchor layer is 200% or more, such applied external force can be absorbed and relaxed as deformation of the anchor layer. For this reason, it can suppress that the coating layer for printing peels from a base material based on the malfunction that peeling arises in the interface of an anchor layer and a base material, or an anchor layer cohesively breaks inside. From the viewpoint of more stably realizing the internal relaxation of the anchor layer, the breaking elongation of the anchor layer is preferably 250% or more, and more preferably 300% or more.

  On the other hand, when the breaking elongation of the anchor layer exceeds 500%, there is a concern that the tackiness of the anchor layer becomes excessively large or the blocking resistance of the anchor layer is lowered. From the viewpoint of more stably reducing the possibility of blocking, the breaking elongation of the anchor layer is preferably 480% or less, and more preferably 450% or less.

  In addition, when the anchor layer has a breaking strength of 20 MPa or less, the tensile force or compressive force in the main surface direction that is generated when the ink contracts as the ink cures is opposed to the printing layer of the anchor layer. Even if it is applied to the surface on the side to be engaged, it is possible to reduce the force inside the anchor layer. From the viewpoint of efficiently performing internal relaxation of the anchor layer, the breaking strength of the anchor layer is preferably 17 MPa or less, more preferably 13 MPa or less, and particularly preferably 10 MPa or less. The lower limit of the breaking strength of the anchor layer is not particularly limited, but if it is too low, there is a concern that the strength of the anchor layer is insufficient and there is a risk of cohesive failure inside the anchor layer, resulting in a decrease in printing quality. . Therefore, the breaking strength of the anchor layer is preferably 1 MPa or more, more preferably 2 MPa or more, and particularly preferably 4 MPa or more.

(Mechanical characteristics 2)
The breaking elongation of the anchor layer is 200% or more and 500% or less, and the ratio of the breaking strength to the breaking elongation (unit: MPa /%, also referred to as “S / T ratio” in this specification) is 0.05. It is as follows.

  The reason why the elongation at break of the anchor layer is within the above range and the preferable range are the same as those of the mechanical property 1, and thus the description thereof is omitted.

  When the anchor layer has an S / T ratio of 0.05 MPa /% or less, the tensile force or compressive force in the in-plane direction generated based on the shrinkage of the ink as the ink is cured is imparted to the anchor layer. When this is done, a sufficient amount of deformation of the anchor layer before the anchor layer breaks can be secured based on the applied force. Therefore, the above-described force applied to the anchor layer can be efficiently relaxed by the internal deformation of the anchor layer. From the viewpoint of more efficiently performing the internal relaxation of the anchor layer, the S / T ratio of the anchor layer is preferably 0.04 MPa /% or less, and more preferably 0.03 MPa /% or less. The lower limit of the S / T ratio of the anchor layer is not particularly limited, but if it is too low, there is a concern that the anchor layer is insufficient in strength and may cause cohesive failure inside the anchor layer, resulting in a decrease in print quality. Is done. Therefore, the breaking strength of the anchor layer is preferably 0.005 MPa /% or more, and more preferably 0.02 MPa /% or more.

  The anchor layer according to the present embodiment may satisfy one of the mechanical characteristics 1 and 2, or may satisfy both. From the viewpoint of more stably reducing the possibility of internal fracture of the anchor layer and separation between the anchor layer and the base material, the anchor layer according to the present embodiment satisfies both of the above mechanical properties 1 and 2. It is preferable.

  The composition of the anchor layer is not particularly limited as long as the anchor layer satisfies at least one of the above mechanical properties 1 and 2. When the anchor layer contains a resin material, it is easy to satisfy the above mechanical characteristics, which is preferable.

  When the anchor layer contains a resin material, the type of resin included in the resin material is not particularly limited. For example, polyurethane resin, acrylic modified urethane resin, urethane modified polyester resin, urethane modified acrylic resin, acrylic resin, styrene resin, polyester resin, cured resin of active energy ray curable compound, polyol resin, polyvinyl Specific examples include alcohol, polyvinyl pyrrolidone, cellulose derivatives, acetate derivatives, polyvinyl chloride resins, polyimide resins, latex resins, starch, gelatin, plant proteins, casein, gum arabic, and albumin. When the anchor layer contains a resin material, the resin type included in the resin material may be one type or a plurality of types. When the resin material includes a plurality of types of resins, the blending ratio of these resins is not particularly limited as long as the above mechanical characteristics are satisfied.

  Among these resins, it is preferable to contain a urethane-based resin that is a resin having a urethane bond from the viewpoint of ease of satisfying the above-described mechanical properties. Specific examples of urethane resins include polyurethane resins, acrylic modified urethane resins, urethane modified polyester resins, urethane modified acrylic resins, and the like. The urethane-based resin may be composed of one kind of resin among them, or may be composed of a plurality of kinds of resins.

  When the anchor layer contains a resin-based material, the resin-based material has a heavy chain having a cross-linking agent and a functional group capable of reacting with the cross-linking agent (also referred to as “reactive functional group” in this specification). It preferably contains a crosslinked structure formed by reaction with a coalescence (also referred to as “crosslinkable polymer” in this specification). Although the kind of this crosslinkable polymer is not specifically limited, It is preferable that a crosslinkable polymer contains a urethane type polymer. In this case, a cross-linked product obtained by bonding a cross-linkable polymer via a cross-linking agent is a kind of urethane-based resin that is one of the preferred examples of the above resin.

  The kind of the crosslinking agent that gives such a crosslinked structure is not particularly limited. Examples thereof include polyimine compounds such as epoxy compounds, isocyanate compounds, metal chelate compounds, and aziridine compounds, melamine resins, urea resins, dialdehydes, methylol polymers, metal alkoxides, and metal salts. As will be described later, when the anchor layer forming coating material that is a coating material for forming the anchor layer is aqueous (that is, the solvent and / or the dispersion medium is aqueous), the coating is performed. From the viewpoint of low reactivity between the material and water which is one of the main media, the crosslinking agent is preferably an epoxy compound.

  The epoxy compound may be any compound having two or more epoxy groups or glycidyl groups in the molecule, such as bisphenol A / epichlorohydrin type epoxy resin, sorbitol polyglycidyl ether (for example, manufactured by Nagase ChemteX Corporation). “Denacol EX-611”, “Denacol EX-612”, “Denacol EX-614”, “Denacol EX-614B”, “Denacol EX-622”, etc.), polyglycerol polyglycidyl ether (for example, manufactured by Nagase ChemteX Corporation) "Denacol EX-512", "Denacol EX-521", etc.), pentaerythritol polyglycidyl ether (for example, "Denacol EX-411" manufactured by Nagase ChemteX Corporation), diglycerol polyglycidyl ether (for example, Nagase) "Denacol EX-421" manufactured by Mutex, Inc.), glycerol polyglycidyl ether (for example, "Denacol EX-313", "Denacol EX-314" manufactured by Nagase ChemteX), etc.), trimethylolpropane polyglycidyl ether (for example, , "Denacol EX-321" manufactured by Nagase ChemteX Corporation), neopentyl glycol diglycidyl ether (for example, "Denacol EX-211" manufactured by Nagase ChemteX Corporation), 1,6-hexanediol diglycidyl ether ( For example, “Denacol EX-212” manufactured by Nagase ChemteX, Inc.), ethylene glycol diglycidyl ether (eg, “Denacol EX-810”, “Denacol EX-811” manufactured by Nagase ChemteX, Inc.), diethylene glycol diglycy Luether (for example, “Denacol EX-850”, “Denacol EX-851”, etc., manufactured by Nagase ChemteX), polyethylene glycol diglycidyl ether (eg, “Denacol EX-821”, “Denacol EX, manufactured by Nagase ChemteX) -830 "," Denacol EX-832 "," Denacol EX-841 "," Denacol EX-861 ", etc.), propylene glycol diglycidyl ether (for example," Denacol EX-911 "manufactured by Nagase ChemteX Corporation), Polypropylene glycol diglycidyl ether (for example, “Denacol EX-941”, “Denacol EX-920”, “Denacol EX-931”, etc., manufactured by Nagase ChemteX Corporation), diglycidylaniline, N, N, N ′, N ′ -Tetraglycidyl-m-xyle Diamine, 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane and the like.

  When the crosslinking agent contains an epoxy compound, it may contain one kind of epoxy compound or may contain a plurality of kinds of epoxy compounds.

  It is possible to control the mechanical properties of the anchor layer by adjusting the density of the crosslinked structure existing in the anchor layer according to the present embodiment (also referred to as “crosslinking density” in this specification). Thus, it is preferable to set the breaking elongation and breaking strength so as to satisfy at least one of the mechanical properties 1 and 2 described above. A specific method for adjusting the crosslinking density is arbitrary. Kind and content of crosslinking agent contained in coating material for anchor layer formation, kind and content of crosslinking polymer contained in coating material for anchor layer formation, reactive functional group possessed by crosslinking polymer And the presence ratio of the crosslinkable polymer, the presence or absence of a crosslinking accelerator, and the like, but are not limited thereto.

  As long as the mechanical properties 1 and / or 2 are satisfied, the anchor layer includes, in addition to the above-described components, a crosslinking accelerator; a coloring material such as a dye or a pigment; an antioxidant such as an anilide or phenol; a benzophenone or benzo Ultraviolet absorbers such as triazoles; filler components such as talc, titanium dioxide, silica, and starch; plasticizers; antioxidants; light stabilizers; dispersants;

  The thickness of the anchor layer is not particularly limited, but if it is excessively thin, the above-described internal relaxation is not sufficiently performed in the anchor layer, and it is difficult to reduce the possibility that the printing coat layer is peeled off from the substrate. Is concerned. On the other hand, when the anchor layer is excessively thick, there is a concern that it is disadvantageous in terms of cost. Therefore, from the viewpoint of more stably realizing that the anchor layer performs a desired function at a low cost, the thickness of the anchor layer is preferably 10 nm or more and 5 μm or less, and preferably 20 nm or more and 1 μm or less. 30 nm or more and 0.5 μm or less is more preferable, and 50 nm or more and 0.1 μm or less is particularly preferable.

(3) Coating layer for printing The coating layer for printing provided in the printing sheet according to the present embodiment has adhesion to UV (ultraviolet curable) ink used as ink for flexographic printing, and normal oxidation polymerization type ink. It is a layer provided to improve the thermal transfer printability.

  The material constituting the coating layer for printing is not particularly limited as long as it can form a coating layer for printing with good adhesion to the anchor layer and good adhesion of printing ink. Can be used. Examples of components constituting the coating layer for printing include an organic binder and a roughening agent.

  The organic binder is a film forming component of the coating layer for printing. For example, polyurethane resin, urethane-modified polyester resin, acrylic urethane resin, acrylic resin, styrene resin, polyester resin, active energy ray curable type Specific examples include compound cured resins, polyol resins, polyvinyl alcohol, polyvinyl pyrrolidone, cellulose derivatives, acetate derivatives, polyvinyl chloride resins, polyimide resins, latex resins, starch, gelatin, plant proteins, casein, gum arabic, and albumin. Take as an example.

  It is preferable to use the organic binder having a glass transition temperature in the range of 30 to 95 ° C. If this glass transition temperature is less than 30 ° C., the resulting printing sheet is inferior in blocking resistance, while if the glass transition temperature exceeds 95 ° C., the printability of the printing sheet tends to decrease. The preferable range of the glass transition temperature of the organic binder is 40 to 85 ° C.

  The surface roughening agent moderately roughens the surface of the printing sheet in order to increase the adhesion of the ink (before curing and after curing) to the surface on the printing coat layer side of the printing sheet. is there. Specifically, the surface roughening agent is inorganic such as silica, zirconia, clay, talc, kaolin, diatomaceous earth, alumina, titania, zeolite, calcium carbonate, barium sulfate, aluminum hydroxide, magnesium hydroxide, calcium phosphate, glass, etc. Examples thereof include powders, acrylic resins, urethane resins, vinyl chloride resins, benzoguanamine resins, benzoguanamine / melamine / formaldehyde condensates, ion exchange resins, urea resins, and polystyrene resins.

  When the printing sheet is required to have transparency, this printing coat layer also has transparency. The coating layer for printing can be colored materials such as dyes and pigments, antioxidants such as anilides and phenols, ultraviolet absorbers such as benzophenones and benzotriazoles, plasticizers, antioxidants, You may contain additives, such as a light stabilizer, a dispersing agent, and a leveling agent.

  When the anchor layer contains a resin material, the coating layer for printing contains a resin material similar to that of the resin material, which suppresses the occurrence of peeling at the interface between the coating layer for printing and the anchor layer. From the viewpoint of As described above, the anchor layer preferably contains a resin-based material including a urethane-based resin as a material that can easily satisfy the mechanical properties 1 and / or 2 stably. Therefore, when the anchor layer contains a resin material containing a urethane resin, it is preferable that the print coat layer also contains a resin material containing a urethane resin.

  The thickness of the coating layer for printing is not particularly limited, and should be appropriately set according to the application. If this thickness is excessively thin, it will be difficult to achieve the function of adhering the ink onto the substrate, and if it is excessively thick, there is a concern that problems such as reduced blocking resistance may become apparent. The From the viewpoint of suppressing the occurrence of such problems, the thickness of the coating layer for printing is preferably 40 nm or more and 450 nm or less, and more preferably 60 nm or more and 350 nm or less.

(4) Other components In addition to said base material, an anchor layer, and the coating layer for printing, the printing sheet which concerns on this embodiment may be provided with the other component. As such a component, a pressure-sensitive adhesive layer laminated on the surface of the base material opposite to the side facing the anchor layer can be mentioned.

  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.

  In the present embodiment, 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 opposite to the side facing the substrate may be exposed, but usually a release material is temporarily attached to protect the pressure-sensitive adhesive layer until use.

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

  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 those containing a silicone resin, an alkyd resin, a fluororesin, a long-chain alkyl-containing resin, and the like. 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.

  The thickness of the support base material of the release material is not particularly limited, but is usually about 15 μm or more and 300 μm or less.

2. Anchor Layer Forming Coating Material The anchor layer provided in the printing sheet according to the present embodiment can be formed using an anchor layer forming coating material described below. In this specification, “anchor layer-forming coating material” is a material that contains a component for forming an anchor layer and is used in an application process for forming an anchor layer, and is 23 ° C., relative It means a material that has fluidity when placed in an environment of 50% humidity, and includes not only a low-viscosity liquid but also a viscous material having a certain degree of viscosity when applied. Moreover, the component for forming an anchor layer may be contained as a solute, and may be contained as a dispersoid.

  The coating material for forming the anchor layer is not particularly limited as long as it contains a component for forming an anchor layer that can satisfy the above-mentioned mechanical properties 1 and / or 2. A solvent (may be a dispersion medium at the same time) may be contained for the purpose of adjusting the thickness of the anchor layer.

  When the anchor layer formed by the anchor layer forming coating material contains a resin material, and the resin material includes a urethane resin, the anchor layer forming coating material is water-dispersed polyurethane, water-dispersed. It is preferable that at least one film-forming component includes one or more urethane-based components selected from the group consisting of acrylic-modified polyurethane and urethane acrylic emulsion. As described above, since the resin material contained in the anchor layer preferably contains a urethane resin, it contains a urethane component capable of forming such a urethane resin as at least one of the film forming components. The coating material is preferable as the anchor layer forming coating material according to the present embodiment.

  In addition, when the resin material contained in the anchor layer formed by the anchor layer forming coating material includes a crosslinked structure, the anchor layer forming coating material provides the crosslinked structure. Containing a functional polymer. As described above, the type of the crosslinking agent is not particularly limited. However, when the anchor layer-forming coating material contains water as a solvent and / or dispersion medium, such as when the urethane-based component is contained, an aqueous system is used. From the viewpoint of high stability in the coating material, the crosslinking agent is preferably an epoxy compound.

  Furthermore, when the anchor layer forming coating material contains a crosslinking agent and a crosslinkable polymer, it is preferable that at least a part of the urethane-based component is a crosslinkable polymer. In this case, the urethane component has a reactive functional group. When the crosslinking agent is an epoxy compound and the anchor layer forming coating material is aqueous, examples of the reactive functional group include an amino group, an amide group, and a carboxylic acid group.

  The coating material for forming the anchor layer may appropriately contain additives such as a coloring material, an antioxidant, and an ultraviolet absorber depending on the component that the anchor layer should contain. What is necessary is just to set those content suitably according to a composition of an anchor layer.

  The method for preparing the anchor layer-forming coating material is not limited. In some cases, it is only necessary to mix components for forming the anchor layer, and in some cases, the component and a solvent (which may be a dispersion medium at the same time). In some cases. When the component for forming an anchor layer contains what should be melt | dissolved in a solvent, you may heat a solvent so that the component may melt | dissolve appropriately.

3. Manufacturing method of printing sheet The manufacturing method of the printing sheet according to the present embodiment is not particularly limited, and these may be appropriately laminated so that the anchor layer is disposed between the base material and the coating layer for printing. Good. A specific example of the manufacturing method is as follows.

  First, the above-mentioned anchor layer forming coating material is applied on one surface of a substrate to form a coating film of the anchor layer forming coating material on the substrate. This coating method is not particularly limited, and conventionally known methods such as a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, and the like can be used.

  Next, the coating film of the anchor layer forming coating material is dried to obtain a laminate in which the anchor layer is laminated on the substrate. The drying conditions are arbitrary as long as sufficient drying is possible, and may be left at room temperature, or the above-mentioned coating film may be heated to about 80 ° C., for example. What is necessary is just to set drying time suitably according to the thickness of a coating film, drying temperature, etc. For example, when the above-mentioned coating film is heated to about 80 ° C., the heating time can be about several minutes or less.

  Subsequently, a printing coat layer forming material, which is a coating material for forming a printing coat layer, is applied on the surface of the laminate on the anchor layer side. Similar to the anchor layer forming coating solution, this printing coat layer forming material contains a component for forming a coat layer, and optionally contains a solvent or a dispersion medium. By applying the coating layer forming material for printing, a coating film of the coating layer forming material is formed on the anchor layer.

  When the coating film for forming the coating layer for printing is thus obtained, the coating sheet is dried to obtain a printing sheet including the substrate, the anchor layer, and the coating layer for printing. This drying condition should be set appropriately as in the case of forming the anchor layer.

  When the anchor layer-forming coating material contains a crosslinking agent and a crosslinkable polymer so that the anchor layer includes a crosslinked structure, drying conditions in the drying step for forming the anchor layer are appropriately set (specifically Specifically, it is exemplified that the coating film is heated to about 60 ° C. or more.) The reaction between the crosslinking agent in the coating film and the crosslinkable polymer can be advanced. Thus, the crosslinking reaction may be advanced by this drying step, or the above reaction may be allowed to proceed in another step, for example, a drying step for forming a coating layer for printing. Furthermore, in order to advance said reaction, you may provide the curing process of leaving still for several days, for example in an environment of 23 degreeC and 50% of relative humidity after the drying process for forming an anchor layer.

  When providing a pressure-sensitive adhesive layer on the surface opposite to the side facing the anchor layer of the substrate, the pressure-sensitive adhesive layer is on the surface opposite to the surface on which the printing coat layer on the substrate is laminated, You may provide by applying the coating liquid for forming an adhesive layer, or apply | coat said coating liquid to the peeling surface of a peeling material, form an adhesive layer, and this adhesive layer is formed. You may form an adhesive layer with a peeling material by bonding together the surface on the opposite side to the coating layer side for printing of a base material. 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.

  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]
(1) Preparation of anchor layer Polyurethane resin (made by Arakawa Chemical Co., Ltd., trade name “Yuriano w600”) is diluted with a water / isopropyl alcohol mixed solvent (water: isopropyl alcohol = 8: 2) (mass ratio) to obtain a solid content. A 1.5% coating solution was prepared. The above coating solution was applied to one side of a 50 μm-thick biaxially stretched polypropylene film as a substrate by bar coating so that the thickness after drying was 100 nm, and dried at 90 ° C. for 1 minute. . The film thickness after drying was measured with a spectroscopic ellipsometer (manufactured by JA Woollan, M-2000).

(2) Production of printing coat layer (production of printing sheet)
50 parts by mass of urethane-modified polyester resin (product name “Byron UR1400” manufactured by Toyobo Co., Ltd.), 50 parts by mass of urethane-modified polyester resin (product name “Byron UR3200” manufactured by Toyobo Co., Ltd.) and hexamethylene diisocyanate crosslinking agent (Japan) 2 parts by mass of polyurethane (trade name “Coronate HL”) were mixed and diluted with toluene to prepare a coating solution having a solid content of 1.5%.
This coating solution is applied onto the anchor layer by bar coating, dried at 90 ° C. for 1 minute, coated to a thickness of 100 nm after drying, and provided with a coating layer for printing. Got.

[Example 2]
In the preparation of the coating liquid for forming the anchor layer, in addition to the polyurethane resin used in Example 1, an epoxy-based crosslinking agent (trade name “Denacol EX-313” manufactured by Nagase ChemteX Corporation) A printed sheet was obtained in the same manner as in Example 1 except that 5 parts were mixed to obtain the anchor layer.

Example 3
In the preparation of the coating liquid for forming the anchor layer, instead of the polyurethane resin used in Example 1, another polyurethane resin (manufactured by Arakawa Chemical Co., Ltd., trade name “Yuriano w300”) was used. A printed sheet was obtained in the same manner as in Example 1.

Example 4
When preparing the coating liquid for forming the anchor layer, instead of the polyurethane resin used in Example 1, another polyurethane resin (trade name “Yuriano w321” manufactured by Arakawa Chemical Co., Ltd.) was used. A printed sheet was obtained in the same manner as in Example 1.

[Comparative Example 1]
When preparing the coating liquid for forming the anchor layer, another polyurethane resin (trade name “Takelac ws-5100” manufactured by Mitsui Chemicals, Inc.) was used instead of the polyurethane resin used in Example 1. A printed sheet was obtained in the same manner as Example 1 except for the above.

[Comparative Example 2]
When preparing the coating liquid for forming the anchor layer, another polyurethane resin (trade name “Takelac ws-6021” manufactured by Mitsui Chemicals, Inc.) was used instead of the polyurethane resin used in Example 1. A printed sheet was obtained in the same manner as Example 1 except for the above.

[Comparative Example 3]
When preparing the coating liquid for forming the anchor layer, another polyurethane resin (trade name “Takelac ws-5000” manufactured by Mitsui Chemicals, Inc.) was used instead of the polyurethane resin used in Example 1. A printed sheet was obtained in the same manner as Example 1 except for the above.

[Comparative Example 4]
When preparing the coating solution for forming the anchor layer, another polyurethane resin (trade name “Takelac w-5030” manufactured by Mitsui Chemicals, Inc.) was used instead of the polyurethane resin used in Example 1. A printed sheet was obtained in the same manner as Example 1 except for the above.

[Comparative Example 5]
Other than using an acrylic-modified urethane resin (manufactured by Chuo Rika Kogyo Co., Ltd., trade name “Rikabond SU200”) in place of the polyurethane resin used in Example 1 in preparing the coating liquid for forming the anchor layer. Obtained a printed sheet in the same manner as in Example 1.
[Comparative Example 6]
A printed sheet was obtained in the same manner as in Example 1 except that the anchor layer was not used.

[Test Example 1] <Measurement of elongation at break and strength at break>
A release sheet (SP-PET 382120, manufactured by Lintec Co., Ltd., having a width of 1000 mm) prepared by forming a silicone release agent layer having a thickness of 0.1 μm on one main surface of a base film made of polyethylene terephthalate having a thickness of 38 μm is prepared. did. On the release surface of this release sheet, the anchor layer forming coating material used in manufacturing the printing sheet according to the example or the comparative example is dried with a knife coater, and the thickness of the anchor layer obtained after drying is 20 μm. It applied so that it might become. The resulting coating film is dried together with the release sheet in an oven at 80 ° C. for 1 minute to dry the coating film, and the reaction between the crosslinking agent and the crosslinkable polymer inside the anchor layer forming coating material proceeds. Thus, a laminate composed of a release sheet and an anchor layer (thickness 20 μm) was obtained.
This laminate was left for 2 weeks in an atmosphere of 23 ° C. and 50% relative humidity. Thereafter, the laminate was cut into a size of 15 mm width × 140 mm length, and the two release sheets of the cut laminate were peeled to obtain a sample for measuring mechanical properties. The obtained mechanical property measurement sample was set in a universal tensile tester (manufactured by SHIMADZU, Autograph AG-10kNIS) so that the measurement range was 15 mm wide × 25 mm long. Then, in an environment of 23 ° C. and 50% relative humidity, the mechanical property measurement sample was stretched in the major axis direction at a tensile speed of 200 mm / min, and the elongation at the time when the mechanical property measurement sample broke was determined as the elongation at break. It was. Further, the tensile force applied to the sample for measuring mechanical properties at the time of breaking was defined as breaking strength. From the obtained breaking elongation and breaking strength, the ratio (unit: MPa /%) of breaking strength to breaking elongation was determined. Table 1 shows the results of the breaking elongation, breaking strength, and ratio of breaking strength to breaking elongation.

[Test Example 2] <Evaluation of peel resistance of printed coat layer>
Based on the cross-cut method of JIS K5600 5.6: 1999 (ISO 2409: 1992) on the surface on which the anchor layer and the print coat layer of the printing sheet are formed, the cut interval is 1 mm and the cut lines are 10 × 10. A cross cut part having a grid number of 100 was prepared, and the adhesion between the coat layer and the substrate was evaluated.
The remaining rate was expressed as x / 100, where x is the number of squares remaining after tape peeling. 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 peel resistance of UV ink>
Using the UV ink (T & K TOKA, Flexo White HT-2), flexographic printing is performed on the surface of the printing sheet of the printing sheet with a flexographic printing machine (Merkandy, MA-2200, printing speed 50 m / min). UV irradiation (metal halide lamp 4 kW) was performed to obtain a printed image. The cell of the anilox roller of the flexographic printing machine was a turtle shell type # 200, and the cell capacity was 16 cm ³ / m ² . The printing sheet on which the printed image was formed by performing each printing was left still for 24 hours in an environment of 23 ° C. and 50% relative humidity. After that, on the surface of the printing sheet on which the printed image is formed, the cut image is formed on the surface on which the printed image is formed 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 was prepared as 10 × 10, and the adhesion between the ink and the printing sheet on which the printed image was formed was evaluated.
The remaining rate was expressed as x / 100, where x is the number of squares remaining after tape peeling. An x / 100 value of 90/100 or higher was considered acceptable. The evaluation results are shown in Table 1.

[Test Example 4] <Evaluation of peel resistance after water resistance>
About the printing sheet in which the printed image was formed by the said printing, the printing sheet was immersed for 24 hours in the beaker containing the pure water of 23 degreeC. Based on the cross-cut method of JIS K 5600 5.6: 1999 (ISO 2409: 1992) on the side of the printing sheet on which the printed image is formed, the cut interval is 1 mm and the cut lines are 10 × 10. A cross-cut portion having a grid number of 100 was prepared, and the water-resistant adhesion between the ink and the printing sheet on which the printed image was formed was evaluated.
The remaining rate was expressed as x / 100, where x is the number of squares remaining after tape peeling. An x / 100 value of 90/100 or higher was considered acceptable. The evaluation results are shown in Table 1.

  FIG. 1 is a graph in which the results of Measurement Example 1 are plotted with the breaking strength as the vertical axis and the breaking elongation as the horizontal axis. In FIG. 1, the result of the example is indicated by “◯”, and the result of the comparative example is indicated by “●”. In order to clarify the scope of the present invention, FIG. 1 shows breaking elongation = 200% (broken line), breaking elongation = 500% (broken line), breaking strength = 20 MPa (dashed line) and breaking strength. Each line of the ratio to the elongation at break = 0.05 MPa% (dotted line) is also shown.

  As shown in Table 1 and FIG. 1, according to the printing sheet of the example satisfying the conditions of the present invention, the base material of the printing sheet is a polyolefin-based resin sheet and is an ink for flexographic printing. However, internal fracture of the anchor layer and peeling at the interface between the base material and the anchor layer hardly occur.

  Since the printing sheet of the present invention hardly peels off UV ink, even if the base material of the printing sheet is made of a polyolefin-based resin sheet such as OPP, it can be suitably used for flexographic printing.

Claims (10)

For printing comprising a sheet-like base material, an anchor layer laminated on one surface of the base material, and a printing coat layer laminated on the surface of the anchor layer opposite to the side facing the base material A sheet,
The anchor layer has a breaking elongation of 200% to 500% and a breaking strength of 20 MPa or less. A printing sheet comprising a sheet-like base material, an anchor layer laminated on one surface of the base material, and a printing coat layer laminated on the surface of the anchor layer opposite to the base material side. And
The anchor layer has a breaking elongation of 200% to 500%, and a ratio of a breaking strength to a breaking elongation (unit: MPa /%) is 0.05 or less.   The printing sheet according to claim 2, wherein the anchor layer has a breaking strength of 20 MPa or less.   The printing sheet according to any one of claims 1 to 3, wherein the anchor layer includes a resin material, and the resin material includes a crosslinked structure formed by a reaction between a crosslinking agent and a crosslinkable polymer. .   The anchor layer has a breaking elongation and a breaking strength of the anchor layer set in a range described in claim 1 or 2 by adjusting a density of the cross-linking structure existing in the anchor layer. The printing sheet according to claim 4.   The printing sheet according to claim 4, wherein the crosslinkable polymer includes a urethane polymer.   The printing sheet according to claim 4, wherein the crosslinking agent contains an epoxy-based crosslinking agent.   The printing sheet according to claim 1, wherein the base material contains an olefin resin.   The coating material for forming the anchor layer with which the printing sheet as described in any one of Claim 1 to 8 is provided. A method for producing a printing sheet according to any one of claims 1 to 8,
An anchor layer forming coating material comprising the coating material according to claim 9 is applied onto one surface of the base material, and the coating film of the anchor layer forming coating material is applied onto the base material. Forming, and
Drying the coating film of the anchor layer forming coating material to obtain a laminate in which the anchor layer is laminated on the substrate;
Applying a coating layer forming material for printing on the surface of the laminate on the anchor layer side to form a coating film of the coating layer forming material on the anchor layer;
Drying the coating film of the printing coat layer forming material to obtain the printing sheet comprising the substrate, the anchor layer, and the printing coat layer. Manufacturing method.

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