Active energy ray curable offset printing ink composition

Abstract

This actinic ray-curable offset printing ink composition contains an actinic ray-polymerizable compound having a (meth)acryloyl group. The concentration of the (meth)acryloyl group is 2.2 to 4.5 mol / g, and the glass transition temperature of the polymer obtained by polymerization of the actinic ray-polymerizable compound is -20°C to 25°C.

Description

Technical Field

[0001] The present invention relates to an active energy ray-curable offset printing ink composition. More specifically, the present invention relates to an active energy ray-curable offset printing ink composition capable of producing a laminate having excellent laminate strength.

Background Art

[0002] Active energy ray-curable printing ink compositions are excellent in workability because they are instantaneously cured by irradiation with electron beams, ultraviolet rays, etc. Active energy ray-curable printing ink compositions are used without solvents, so they have a low environmental impact. Therefore, as shown in Patent Document 1, active energy ray-curable inks are used as flexible packaging materials such as food packaging materials.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] However, the ink composition described in Patent Document 1 does not have sufficient laminate strength (peel strength, seal strength) of the laminate.

[0005] The present invention has been made in view of such conventional problems, and an object thereof is to provide an active energy ray-curable offset printing ink composition capable of producing a laminate having excellent laminate strength.

[0006] An active energy ray-curable offset printing ink composition according to one aspect of the present invention, which solves the above problems, comprises an active energy ray-polymerizable compound having a (meth)acryloyl group, wherein the concentration of the (meth)acryloyl group is 2.2 to 4.5 mol / g, and the glass transition temperature of the polymer obtained by polymerizing the active energy ray-polymerizable compound is -20°C to 25°C.

[0007] A laminate according to one aspect of the present invention, which solves the above problems, includes a printed layer to which the above-mentioned active energy ray curable offset printing ink composition is applied, wherein the printed layer is provided on a first substrate, and a second substrate is provided on the printed layer. [Modes for carrying out the invention]

[0008] <Activated energy ray curing type offset printing ink composition> An active energy ray-curable offset printing ink composition (hereinafter also referred to as the ink composition) according to one embodiment of the present invention contains an active energy ray polymerizable compound having a (meth)acryloyl group. The concentration of the (meth)acryloyl group is 2.2 to 4.5 mol / g. The glass transition temperature of the polymer obtained by polymerizing the active energy ray polymerizable compound is -20°C to 25°C. Each of these will be explained below.

[0009] ((meth)acryloyl group-containing active energy ray polymerizable compound) The ink composition contains an active energy ray polymerizable compound having a (meth)acryloyl group. The active energy ray polymerizable compound having a (meth)acryloyl group is not particularly limited. For example, the active energy ray polymerizable compound having a (meth)acryloyl group preferably contains a resin having a (meth)acryloyl group and a polyfunctional (meth)acrylate having a skeleton derived from alkylene oxide. As a result, when the ink composition is applied to a substrate and cured, and then a laminate is made by laminating a film via an adhesive, the laminate strength is improved.

[0010] • Resins having (meth)acryloyl groups The resin having (meth)acryloyl groups is not particularly limited. For example, resins having (meth)acryloyl groups include urethane acrylate resins, polyester acrylate resins, epoxy acrylate resins, and acrylic resin acrylates. Among these, it is preferable that the resin having (meth)acryloyl groups includes urethane acrylate resin. This increases the adhesion of the ink composition to the substrate and also increases the lamination strength.

[0011] The urethane acrylate resin is not particularly limited. For example, the urethane acrylate resin is a resin obtained by condensing an isocyanate group-containing monomer and a hydroxyl group-containing monomer, and modifying the ends of the urethane resin with an acrylic group or a methacrylic group. Among these, the urethane acrylate resin preferably has an acid value of 3 mg KOH / g or less. Furthermore, the urethane acrylate resin preferably contains an aliphatic urethane acrylate resin. Moreover, it is more preferable that the urethane acrylate resin contains a urethane acrylate resin with an acid value of 3 mg KOH / g or less, and even more preferable that it is a urethane acrylate resin without difunctional acid groups modified at both ends with an acrylic group or a methacrylic group. As a result, the ink composition can suppress the incorporation of water into the ink due to the acid value and suppress excessive emulsification, which reduces fouling of printed materials during printing. Furthermore, suppressing the emulsification rate leads to suppression of the ink film thickness of the printed material. Reducing film thickness also leads to reduced internal stress after coating hardening, resulting in improved adhesion to the substrate and increased laminate strength.

[0012] The mass-average molecular weight of the resin having (meth)acryloyl groups is preferably 10,000 or less, more preferably 5,000 or less, and even more preferably 2,500 or less. Furthermore, the mass-average molecular weight of the resin having (meth)acryloyl groups is preferably 500 or more. Having the mass-average molecular weight of the urethane acrylate resin within the above range leads to suppression of the molecular weight of the cured product after reaction, which increases the flexibility of the coating film, thereby improving adhesion to the substrate and lamination strength due to suppression of internal stress. The number of functional groups (acryloyl groups) of the urethane acrylate is preferably 2 to 6, and more preferably 2 to 3.

[0013] The content of the resin having (meth)acryloyl groups is not particularly limited. For example, the content of the resin having (meth)acryloyl groups is preferably 10% by mass or more, and more preferably 25% by mass or more, in the ink composition. Furthermore, the content of the resin having (meth)acryloyl groups is preferably 55% by mass or less, and more preferably 45% by mass or less. When the content of the resin having (meth)acryloyl groups is within the above range, adhesion and lamination strength are improved.

[0014] • Polyfunctional (meth)acrylate having a skeleton derived from alkylene oxide The polyfunctional (meth)acrylate having an alkylene oxide-derived skeleton is not particularly limited. For example, it is preferable to include an alkylene oxide-modified polyfunctional (meth)acrylate containing 6 to 30 alkylene oxide units in the molecule, as this can further enhance adhesion to the substrate and lamination strength.

[0015] More specifically, polyfunctional (meth)acrylates having an alkoxy-modified polyfunctional (meth)acrylate alkylene skeleton include di(meth)acrylate of ethylene oxide (4 molar) adduct of propylene glycol, di(meth)acrylate of ethylene oxide (3 molar) adduct of glycerin, tri(meth)acrylate of ethylene oxide (3 molar) adduct of glycerin, di(meth)acrylate of propylene oxide (3 molar) adduct of glycerin, di(meth)acrylate of ethylene oxide (3 molar) adduct of diglycerin, tri(meth)acrylate of ethylene oxide (3 molar) adduct of diglycerin, di(meth)acrylate of propylene oxide (3 molar) adduct of diglycerin, di(meth)acrylate of ethylene oxide (3 molar) adduct of trimethylolpropane, and trimethylolpropane. Examples include tri(meth)acrylate of the ethylene oxide (3 molar) adduct of ropane, di(meth)acrylate of the propylene oxide (3 molar) adduct of trimethylolpropane, tri(meth)acrylate of the propylene oxide (3 molar) adduct of trimethylolpropane, di(meth)acrylate of the ethylene oxide (2 molar) adduct of pentaerythritol, tri(meth)acrylate of the ethylene oxide (3 molar) adduct of pentaerythritol, tetra(meth)acrylate of the ethylene oxide (4 molar) adduct of pentaerythritol, di(meth)acrylate of the alkylene oxide (2 molar) adduct of bisphenol, di(meth)acrylate of the alkylene oxide (4 molar) adduct of bisphenol, and di(meth)acrylate of the alkylene oxide (6 molar) adduct of bisphenol. Furthermore, poly(meth)acrylates of polyalkylene glycols include (poly)polyethylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and triethylene glycol diacrylate, as well as (poly)propylene glycol di(meth)acrylates such as propylene glycol di(meth)acrylate and dipropylene glycol di(meth)acrylate.Among these, polyfunctional (meth)acrylates having an alkylene oxide-derived skeleton preferably include alkylene oxide-modified trimethylolpropane triacrylate containing 6 to 30, more preferably 6 to 30, alkylene oxide units in the molecule. This improves the adhesion and lamination strength of the ink composition to the substrate.

[0016] The content of polyfunctional (meth)acrylate having an alkylene oxide-derived skeleton in the ink composition is 10% by mass or more, preferably 20% by mass or more. Furthermore, the content of polyfunctional (meth)acrylate having an alkylene oxide-derived skeleton in the ink composition is 80% by mass or less, preferably 60% by mass or less. By having the content of polyfunctional (meth)acrylate having an alkylene oxide-derived skeleton within the above range, the ink composition exhibits improved adhesion to the substrate and lamination strength.

[0017] Returning to the description of active energy ray polymerizable compounds having (meth)acryloyl groups, the method for preparing active energy ray polymerizable compounds having (meth)acryloyl groups is not particularly limited. For example, an active energy ray polymerizable compound having (meth)acryloyl groups can be prepared by mixing a resin having acryloyl groups with a polyfunctional (meth)acrylate having a skeleton derived from alkylene oxide using a stirrer such as a disper. If the resin having acryloyl groups is solid at room temperature, or if stirring is difficult due to the viscosity of the resin itself, the mixture may be mixed by heating as needed.

[0018] The concentration of (meth)acryloyl groups may be 2.2 mol / g or higher. Alternatively, the concentration of (meth)acryloyl groups may be 4.5 mol / g or lower, and preferably 3.0 mol / g or lower. If the concentration of (meth)acryloyl groups is less than 2.2 mol / g, when the ink composition is applied to a substrate and cured, and then a laminate is made by laminating a film via an adhesive, the adhesion to the substrate and the lamination strength will be poor in the image area. On the other hand, if the concentration of (meth)acryloyl groups exceeds 4.5 mol / g, when the ink composition is applied to a substrate and cured, and then a laminate is made by laminating a film via an adhesive, the adhesion to the substrate and the lamination strength will be poor in the image area.

[0019] When polymers are produced by polymerizing active energy ray polymerizable compounds, the glass transition temperature of the polymer should be -20°C or higher, and preferably -5°C or higher. Furthermore, the glass transition temperature of the polymer should be 25°C or lower, and preferably 20°C or lower. If the glass transition temperature of the polymer is below -20°C, the ink composition is prone to stickiness of the coating film. This stickiness leads to surface tackiness, causing the printed material to adhere to the rotating rolls (guide rolls) and wrinkles during secondary processing (lamination). On the other hand, if the glass transition temperature of the polymer exceeds 25°C, the ink coating film hardens, and when the substrate is bent, cracks may occur on the coating film surface, leading to cracking and peeling of the coating film.

[0020] (Coloring agent) The ink composition of this embodiment preferably contains a colorant. The colorant is an organic pigment, an inorganic pigment, etc., for imparting coloring power to the ink composition. In this embodiment, the colorant also includes a white pigment for making the ink composition white, a metallic powder pigment for imparting metallic colors such as gold or silver, and an inorganic pigment for imparting pearlescent colors.

[0021] For example, the colorant includes yellow pigments such as disazo yellow (Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 17, Pigment Yellow 1), Hansa yellow, magenta pigments such as Brilliant Carmine 6B, Lake Red C, and Watching Red, cyan pigments such as phthalocyanine blue, phthalocyanine green, and alkali blue, black pigments such as carbon black, fluorescent pigments, white pigments such as titanium oxide, gold powder, bronze powder, aluminum paste processed from aluminum powder into a paste form, mica powder, and the like.

[0022] When a colorant is included, the content of the colorant is not particularly limited. For example, the content of the colorant is preferably 10% by mass or more in the ink composition. Also, the content of the colorant is preferably 70% by mass or less in the ink composition. When preparing a yellow ink composition using a yellow pigment, a magenta ink composition using a magenta pigment, a cyan ink composition using a cyan pigment, and a black ink composition using a black pigment respectively, as a complementary color, pigments of other colors may be used in combination or ink compositions of other colors may be added.

[0023] (Extender pigment) The ink composition preferably contains an extender pigment in order to impart viscoelasticity to the ink composition, adjust fluidity, prevent misting, and the like.

[0024] The extender pigment is not particularly limited. For example, the extender pigment includes clay, talc, mica, kaolinite (kaolin), barium sulfate, magnesium sulfate, calcium carbonate, silicon oxide, aluminum oxide, bentonite, heavy calcium carbonate, barium carbonate, zirconia, alumina, and the like. The extender pigment may be in powder form or in a dispersed liquid form dispersed in a suitable solvent. The average particle diameter of the extender pigment is preferably 0.001 to 100 μm, more preferably 0.01 to 50 μm, and even more preferably 0.05 to 5 μm. The BET specific surface area of the extender pigment is 1 to 350 m 2It is preferably from 10 to 70 m / g, 2 more preferably from 20 to 50 m / g, 2 and even more preferably from 40 to 50 m / g.

[0025] When the extender pigment is included, the content of the extender pigment is not particularly limited. For example, the content of the extender pigment is preferably more than 0% by mass, more preferably 1% by mass or more in the ink composition. Also, the content of the extender pigment is preferably 30% by mass or less, more preferably 15% by mass or less in the ink composition. By the content of the extender pigment being within the above range, the ink composition is easily adjusted in viscoelasticity and fluidity, and is easily prevented from misting.

[0026] (Metal chelating agent) The ink composition of the present embodiment preferably contains a metal chelating agent. The metal chelating agent is not particularly limited. For example, the metal chelating agent is an aluminum-based chelating agent, a titanium-based chelating agent, a zirconium-based chelating agent, or the like. Specifically, the metal chelating agent is an aluminum-based chelating agent such as aluminum triisopropoxide, aluminum tributoxide, aluminum dipropoxide monoacetylacetate, aluminum diisopropoxide monoethyl acetoacetate, aluminum dibutoxide monoacetylacetate, and aluminum triacetylacetate; a titanium-based chelating agent such as tetraisopropoxytitanium, tetrabutoxytitanium, and dipropoxybis(acetylacetonato)titanium; a zirconium-based chelating agent such as tetrabutoxyzirconium, or the like.

[0027] When the metal chelating agent is included, the content of the metal chelating agent is preferably 0.1% by mass or more, more preferably 0.5% by mass or more in the ink composition. Also, the content of the metal chelating agent is preferably 10% by mass or less, more preferably 5% by mass or less in the ink composition. By the content of the metal chelating agent being within the above range, the ink composition is excellent in adhesion and laminating strength.

[0028] (Other photopolymerizable compounds) The ink composition of this embodiment may also contain other photopolymerizable compounds besides the active energy ray polymerizable compound having the (meth)acryloyl group, as long as the performance does not deteriorate.

[0029] ·monomer Monofunctional monomers include alkyl acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, and dodecyl (meth)acrylate; (meth)acrylic acid; (meth)acrylates of ethylene oxide adducts; (meth)acrylates of propylene oxide adducts; isobornyl (meth)acrylate; cyclohexyl (meth)acrylate; tricyclodecane monomethylol (meth)acrylate; 2-hydroxyethyl (meth)acrylate; 2-hydroxypropyl (meth)acrylate; 3-hydroxypropyl (meth)acrylate; 2-hydroxybutyl (meth)acrylate; 4-hydroxybutyl (meth)acrylate; hydroxypentyl (meth)acrylate; 2-hydroxy-3-phenoxypropyl (meth)acrylate; and 2-hydroxy-3-butoxypropyl (meth)acrylate. These include phosphates, 2-hydroxy-3-methoxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, glycerin mono(meth)acrylate, acrylic acid phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, β-carboxyethyl (meth)acrylate, (meth)acrylate dimer, ω-carboxypolycaprolactone mono(meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-vinylpyrrolidone, N-vinylformamide, (meth)acryloylmorpholine, vinylmethyloxaziridinone, etc.

[0030] Monomers with two or more functions include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, pentyl glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hydroxypivalyl hydroxypivalate di(meth)acrylate, hydroxypivalyl hydroxypivalate dicaprolactone di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,2-hexanediol di(meth)acrylate, and 1,5-hexa 2,5-Hexanediol di(meth)acrylate, 1,7-Heptanediol di(meth)acrylate, 1,8-Octanediol di(meth)acrylate, 1,2-Octanediol di(meth)acrylate, 1,9-Nonanediol di(meth)acrylate, 1,2-Decanediol di(meth)acrylate, 1,10-Decanediol di(meth)acrylate, 1,2-Decanediol di(meth)acrylate, 1,12-Dodecanediol di(meth)acrylate, 1,2-Dodecanediol di(meth) Acrylate, 1,14-tetradecanediol di(meth)acrylate, 1,2-tetradecanediol di(meth)acrylate, 1,16-hexadecanediol di(meth)acrylate, 1,2-hexadecanediol di(meth)acrylate, 2-methyl-2,4-pentanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-methyl-2-propyl-1,3-propanediol di(meth)acrylate, 2,4-dimethyl-2,4-pentanediol di(meth)acrylate, 2,2-di Ethyl-1,3-propanediol di(meth)acrylate, 2,2,4-trimethyl-1,3-pentanediol di(meth)acrylate, dimethylol octanediolic di(meth)acrylate, 2-ethyl-1,3-hexanediol di(meth)acrylate, 2,5-dimethyl-2,5-hexanediol di(meth)acrylate, 2-methyl-1,8-octanediolic di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 2,4-diethyl-1,5-pentanediol di(meth)acrylate,1,2-Hexanediol di(meth)acrylate, 1,5-Hexanediol di(meth)acrylate, 2,5-Hexanediol di(meth)acrylate, 1,7-Heptanediol di(meth)acrylate, 1,8-Octanediol di(meth)acrylate, 1,2-Octanediol di(meth)acrylate, 1,9-Nonanediol di(meth)acrylate, 1,2-Decanediol di(meth)acrylate, 1,10-Decanediol di(meth)acrylate, 1,2-Decanediol di(meth)acrylate, 1,12-Dodeca 1,2-dodecanediol di(meth)acrylate, 1,14-tetradecanediol di(meth)acrylate, 1,2-tetradecanediol di(meth)acrylate, 1,16-hexadecanediol di(meth)acrylate, 1,2-hexadecanediol di(meth)acrylate, 2-methyl-2,4-pentanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-methyl-2-propyl-1,3-propanediol di(meth)acrylate, 2,4- Methyl-2,4-pentanediol di(meth)acrylate, 2,2-diethyl-1,3-propanediol di(meth)acrylate, 2,2,4-trimethyl-1,3-pentanediol di(meth)acrylate, dimethyloloctanedi(meth)acrylate, 2-ethyl-1,3-hexanediol di(meth)acrylate, 2,5-dimethyl-2,5-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 2,4-diethyl-1,5-pentanediol di(meth)acrylate Acrylate tricyclodecane dimethylol di(meth)acrylate, tricyclodecane dimethylol dicaprolactone di(meth)acrylate, bisphenol A tetraethylene oxide adduct di(meth)acrylate, bisphenol F tetraethylene oxide adduct di(meth)acrylate, bisphenol S tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol A tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol F tetraethylene oxide adduct di(meth)acrylate,Difunctional monomers such as hydrogenated bisphenol A di(meth)acrylate, hydrogenated bisphenol F di(meth)acrylate, bisphenol A tetraethylene oxide adduct dicaprolactone di(meth)acrylate, bisphenol F tetraethylene oxide adduct dicaprolactone di(meth)acrylate; trifunctional monomers such as glycerin tri(meth)acrylate, trimethylolpropane tricaprolactone tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylol hexane tri(meth)acrylate, trimethylol octan tri(meth)acrylate, pentaerythritol tri(meth)acrylate; trimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tetracaprolactone tetra(meth)acrylate Examples include acrylates, diglycerin tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ditrimethylolpropane tetracaprolactone tetra(meth)acrylate, ditrimethylolethane tetra(meth)acrylate, ditrimethylolbutane tetra(meth)acrylate, ditrimethylolhexane tetra(meth)acrylate, ditrimethyloloctane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, tripentaerythritol polyalkylene oxide hepta(meth)acrylate, and other monomers with four or more functionalities; etc.

[0031] Furthermore, as a type of monomer, there is epoxidized vegetable oil acrylate, which is obtained by acrylic modification of epoxidized vegetable oil. This is a compound obtained by ring-opening addition of (meth)acrylic acid to the epoxy group of epoxidized vegetable oil, which is epoxidized with an oxidizing agent such as peracetic acid or perbenzoic acid to the double bond of an unsaturated vegetable oil. Unsaturated vegetable oils are triglycerides in which at least one fatty acid has at least one carbon-carbon unsaturated bond. Examples include hemp seed oil, linseed oil, hen oil, oyster oil, olive oil, cocoa oil, kapok oil, kaya oil, mustard oil, apricot kernel oil, tung oil, kukui oil, walnut oil, poppy oil, sesame oil, safflower oil, radish seed oil, soybean oil, thorn oil, camellia oil, corn oil, rapeseed oil, niger oil, rice bran oil, palm oil, castor oil, sunflower oil, grape seed oil, henbit oil, tall oil, pine seed oil, cottonseed oil, coconut oil, peanut oil, and dehydrated castor oil. Since these types of monomers are derived from vegetable oils, they are useful in increasing the amount of biomass components in ink compositions. Various types of epoxidized vegetable oil acrylates are commercially available and may be used.

[0032] • Oligomer Oligomers are also used to impart appropriate viscosity and elasticity to ink compositions. Examples of oligomers include epoxy-modified (meth)acrylates, which are esters of hydroxyl groups formed after ring-opening epoxy groups contained in epoxy compounds such as epoxy resins with acids or bases, and (meth)acrylic acid; rosin-modified epoxy acrylates; polyester (meth)acrylates, which are prepared from polyhydric alcohols, polyhydric carboxylic acids, and acrylic acid or methacrylic acid, and have ester bonds in the main chain and acryloyl or methacryloyl groups at the terminals; and polyether-modified (meth)acrylates, which are esters of terminal hydroxyl groups of polyether compounds and (meth)acrylic acid.

[0033] (Other ingredients) In addition to the components described above, other components may be added to the ink composition of this embodiment as needed. Such other components include resin components, polymerization inhibitors, dispersants, salts such as phosphates, and waxes such as polyethylene wax, olefin wax, and Fischer-Tropsch wax.

[0034] The resin component is a variety of resins that have been conventionally used in printing ink compositions. The resin component is preferably compatible with the above-mentioned photopolymerizable compound, and is more preferably a styrene-acrylic resin, acrylic resin, alkyd resin, rosin-modified alkyd resin, rosin-modified phenolic resin, rosin-modified maleic acid resin, rosin-modified petroleum resin, rosin ester resin, petroleum resin-modified phenolic resin, vegetable oil-modified alkyd resin, petroleum resin, diallyl phthalate resin, etc.

[0035] The polymerization inhibitor is preferably a phenol compound such as butylhydroxytoluene, or tocopherol acetate, nitrosamine, benzotriazole, or hindered amine, with butylhydroxytoluene being more preferred. The addition of a polymerization inhibitor makes it difficult for polymerization reactions to proceed during storage, thus suppressing thickening of the ink composition. The polymerization inhibitor content in the ink composition is typically around 0.01 to 1% by mass.

[0036] Dispersants are suitably used to disperse coloring components and extender pigments contained in ink compositions in a good state. Various types of dispersants are commercially available, such as the DISPERBYK (product name) series manufactured by BIC Chemie Japan Co., Ltd.

[0037] (Method of curing printed materials) The ink composition of this embodiment can be cured into a film by printing on a substrate and then irradiating it with active energy rays. Examples of active energy rays include ionizing radiation such as ultraviolet rays, electron beams, alpha rays, beta rays, and gamma rays. Among these, electron beams and ultraviolet rays (UV) are preferred as active energy rays due to their excellent curability and convenience, and electron beams that do not use photopolymerization initiators are more preferred due to their superior environmental safety.

[0038] Specific energy sources or curing devices include, for example, germicidal lamps, ultraviolet fluorescent lamps, ultraviolet light-emitting diodes (UV-LEDs), carbon arcs, xenon lamps, high-pressure mercury lamps for copying, medium-pressure or high-pressure mercury lamps, ultra-high-pressure mercury lamps, electrodeless lamps, metal halide lamps, ultraviolet light from natural light, or electron beams from scanning or curtain-type electron beam accelerators.

[0039] (Photopolymerization initiator) When ultraviolet light or the like is used as the active energy ray, the ink composition preferably contains a photopolymerization initiator. The photopolymerization initiator is a component that generates radicals when irradiated with active energy rays, and the generated radicals polymerize compounds having ethylenically unsaturated bonds, thereby curing the ink composition.

[0040] The photopolymerization initiator is not particularly limited as long as it generates radicals when irradiated with active energy rays. For example, photopolymerization initiators include benzophenone, diethylthioxanthone, 2-methyl-1-(4-methylthio)phenyl-2-morpholinopropan-1-one, 4-benzoyl-4'-methyldiphenyl sulfide, 1-chloro-4-propoxythioxanthone, isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, and bis-2,6-dimethoxybenzoyl-2,4,4-trimethylpentyl phenyl Examples of photopolymerization initiators include sphingoxides, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2,2-dimethyl-2-hydroxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,4,6-trimethylbenzyl-diphenylphosphine oxide, ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2-benzyl-2-dimethylamino-1-(morpholinophenyl)-butan-1-one. Such photopolymerization initiators are commercially available, for example, from IGM Resins BV under trade names such as Omnirad907, Omnirad369, Omnirad184, Omnirad379, Omnirad819, and Omnirad TPO, and from Lamberti under trade name such as DETX.

[0041] When a photopolymerization initiator is included, the content of the photopolymerization initiator is preferably 1% by mass or more, and more preferably 2% by mass or more, in the ink composition. Furthermore, the content of the photopolymerization initiator is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 13% by mass, in the ink composition. By having the content of the photopolymerization initiator within the above range, the ink composition can achieve both sufficient curability and good internal curability, and costs can also be reduced.

[0042] (Method for manufacturing ink composition) The ink composition of this embodiment can be prepared by conventionally known methods. For example, the ink composition can be prepared by mixing each component, kneading it in a bead mill or a three-roll mill, adding additives (polymerization inhibitors, waxes, etc.) as needed, and adjusting the viscosity as appropriate. The viscosity of the ink composition is preferably 5 to 70 Pa·s at 25°C as measured by a Raleigh viscometer.

[0043] (Printing method for ink compositions, and method for manufacturing laminates) A laminate can be produced by using the ink composition of this embodiment. The laminate of this embodiment includes a printed layer to which the ink composition is applied. The printed layer is provided on a first substrate. A second substrate is provided on the printed layer. To produce the laminate, for example, a base film (first substrate) such as various resin films and various high-performance barrier films is printed with an ink composition other than white one or more times using an offset printing method to form a colored ink layer (printed layer). Next, a white ink composition is optionally printed on the surface side of the colored ink layer (the lower layer from the surface after final lamination) using an offset printing method and cured with active energy rays to obtain a printed material. A resin film or the like (second substrate) is laminated to the side of the white ink composition layer of the obtained printed material, or to the surface side of the single-color ink layer, using various lamination methods to obtain a laminate for packaging bags, etc. In this embodiment, the first substrate, the printing layer, and the second substrate may be laminated in this order, and other layers may be sandwiched in between as needed. For example, an appropriate adhesive layer, vapor deposition layer, or barrier layer may be sandwiched between each layer.

[0044] Lamination methods include, for example, the lamination method and the dry lamination method, in which an adhesive is applied to the surface of a printed material, and then a film-like polymer is laminated to it. The dry lamination method involves applying an adhesive such as a urethane-based or isocyanate-based adhesive to the surface of a layer made of a white ink composition, and then laminating a film-like polymer using a known dry laminating machine. Polyethylene and unoriented polypropylene can be used as resins for the film used in the dry lamination method. Such laminated products can be made into bags and filled with contents. The resin film used in this process is not particularly limited. For example, the resin film may be polyester film such as polyethylene terephthalate (PET), polylactic acid, or polycaprolactone, various printing plastic films such as nylon and vinylon, or films in which a barrier layer coated with metal vapor deposition or a barrier resin is laminated onto these various printing plastic films.

[0045] As described above, according to this embodiment, when the ink composition is applied to a substrate and cured, and then a laminate (a laminate including a first substrate, a printed layer, and a second substrate) is made by laminating a film via an adhesive, the laminate strength is excellent.

[0046] In the resulting laminate, the glass transition temperature of the printed layer (the resin composition constituting the printed layer) is not particularly limited. For example, the glass transition temperature of the printed layer may be -20°C or higher, and more preferably -5°C or higher. Also, the glass transition temperature may be 25°C or lower, and more preferably 20°C or lower. Having the glass transition temperature of the printed layer within the above range reduces the stickiness of the coating film. Stickiness leads to surface tackiness, and suppressing stickiness leads to reduced adhesion to the rotating roll (adhesion to the guide roll) during secondary processing (lamination) of the printed material, reduced wrinkles, and reduced stiffness.

[0047] One embodiment of the present invention has been described above. The present invention is not particularly limited to the above embodiment. The above embodiment mainly describes an invention having the following configuration.

[0048] (1) An active energy ray curable offset printing ink composition comprising an active energy ray polymerizable compound having a (meth)acryloyl group, wherein the concentration of the (meth)acryloyl group is 2.2 to 4.5 mol / g, and the glass transition temperature of the polymer obtained by polymerizing the active energy ray polymerizable compound is -20°C to 25°C.

[0049] With this configuration, the active energy ray curable offset printing ink composition exhibits excellent laminate strength when a laminate is created by applying it to a substrate, curing it, and then laminating a film via an adhesive.

[0050] (2) The active energy ray curable offset printing ink composition according to (1), wherein the active energy ray polymerizable compound having a (meth)acryloyl group comprises a resin having a (meth)acryloyl group and a polyfunctional (meth)acrylate having a skeleton derived from alkylene oxide.

[0051] With this configuration, when an active energy ray-curable offset printing ink composition is applied to a substrate and cured, and then a laminate is created by laminating a film via an adhesive, the laminate strength is superior.

[0052] (3) The active energy ray curable offset printing ink composition according to (1) or (2), further comprising a colorant.

[0053] With this configuration, when an active energy ray-curable offset printing ink composition is applied to a substrate and cured, and then a laminate is created by laminating a film via an adhesive, it achieves high print density while also exhibiting superior laminate strength in the image areas.

[0054] (4) The active energy ray curable offset printing ink composition according to any one of (1) to (3), further comprising an extender pigment.

[0055] With this configuration, the active energy ray curable offset printing ink composition is easily controllable in terms of viscoelasticity and fluidity, and misting is easily prevented.

[0056] (5) The active energy ray curable offset printing ink composition according to any one of (1) to (4), further comprising a metal chelating crosslinking agent.

[0057] With this configuration, when an active energy ray-curable offset printing ink composition is applied to a substrate and cured, and then a laminate is created by laminating a film via an adhesive, the laminate strength is superior.

[0058] (6) The active energy ray curable offset printing ink composition according to (2), wherein the resin having (meth)acryloyl groups includes a urethane acrylate resin.

[0059] With this configuration, the active energy ray-curable offset printing ink composition exhibits improved adhesion to the substrate and enhanced lamination strength.

[0060] (7) The active energy ray curable offset printing ink composition according to (6), wherein the acid value of the urethane acrylate resin is 3 mg KOH / g or less.

[0061] With this configuration, the active energy ray curable offset printing ink composition can suppress the incorporation of water into the ink due to its acid value, thereby suppressing excessive emulsification, which reduces smudging of printed materials during printing. Furthermore, suppressing the emulsification rate leads to a reduction in the ink film thickness of the printed material. Since a reduction in film thickness also leads to a reduction in internal stress after the coating film has hardened, adhesion to the substrate and lamination strength are improved.

[0062] (8) The urethane acrylate resin comprises an aliphatic urethane acrylate resin, as described in (6) or (7), in the active energy ray curable offset printing ink composition.

[0063] With this configuration, the active energy ray curable offset printing ink composition can suppress the incorporation of water into the ink due to its acid value, thereby suppressing excessive emulsification, which reduces smudging of printed materials during printing. Furthermore, suppressing the emulsification rate leads to a reduction in the ink film thickness of the printed material. Since a reduction in film thickness also leads to a reduction in internal stress after the coating film has hardened, adhesion to the substrate and lamination strength are improved.

[0064] (9) The active energy ray curable offset printing ink composition according to (2), wherein the polyfunctional (meth)acrylate having an alkylene oxide-derived skeleton includes an alkylate oxide-modified polyfunctional (meth)acrylate containing 6 to 30 alkylene oxide units in the molecule.

[0065] With this configuration, the active energy ray-curable offset printing ink composition exhibits improved adhesion to the substrate and enhanced lamination strength.

[0066] A laminate comprising a printing layer to which an active energy ray curable offset printing ink composition according to any one of (1) to (9) is applied, wherein the printing layer is provided on a first substrate and a second substrate is provided on the printing layer.

[0067] With this configuration, the laminate exhibits superior lamination strength. [Examples]

[0068] The present invention will be described more specifically below with reference to examples. The present invention is not limited in any way to these examples. Unless otherwise specified, "%" means "mass%" and "parts" means "parts by mass".

[0069] (Examples 1-21, Comparative Examples 1-9) Based on the formulations described in Tables 1 and 2, active energy ray-curable offset printing ink compositions for Examples 1 to 21 and Comparative Examples 1 to 9 were prepared. The ink compositions were prepared by mixing the raw materials and kneading them in a three-roll mill.

[0070] [Table 1]

[0071] [Table 2]

[0072] The ingredients used are as follows: (Resin having a (meth)acryloyl group)

[0073] [Table 3]

[0074] Resin A: Rosin-modified alkyd resin In a reaction vessel equipped with a stirrer, reflux condenser, and temperature control, 800 parts coconut oil and 36 parts pentaerythritol were mixed and held at 250°C for 1 hour to carry out a transesterification reaction. After cooling to 150°C, 160 parts rosin, 50 parts isophthalic acid, and reflux xylene were added, and the mixture was gradually heated to 250°C and held for 6 hours to carry out a condensation polymerization reaction while dehydrating. To further remove the xylene solvent, the reaction was carried out under reduced pressure for 3 hours to remove the solvent, yielding a rosin-modified alkyd resin with an acid value of 13 mgKOH / g, an sp value of 9.74 by diacritic testing, and a weight-average molecular weight (Mw) of 0.7 million as measured by GPC.

[0075] The properties of each resin are shown in Tables 1 and 2. (Polyfunctional (meth)acrylate with a skeleton derived from alkylene oxide) 3EO-TMPTA: A TMPTA molecule containing three EO units. 6EO-TMPTA: TMPTA M-3160 containing 6 EO units in one molecule. 9EO-TMPTA: TMPTA M3190 containing 9 EO units in one molecule. 15EO-TMPTA: TMPTA M3150 containing 15 EO units per molecule. (Trifunctional acrylic monomer) THEICTA(CAS.NO 40220-08-4):MIRAMER M370(MIWON), Tg:272℃ (Coloring agent) Titanium dioxide: CR-80, manufactured by Ishihara Sangyo Co., Ltd. Phthalocyanine:PB15:3 LIONOL BLUE FG-7330, manufactured by Toyo Color Co., Ltd. Carbon Black: Mogul E, manufactured by Cabot. (Extender pigments) Calcium carbonate: T-DD, manufactured by Shiraishi Calcium Co., Ltd. (Metal chelating agent) ALCH: Aluminum ethyl acetoacetate diisopropylate, manufactured by Kawaken Fine Chemicals Co., Ltd.

[0076] (Method of manufacturing a laminate) The ink composition was transferred in 0.1cc increments to two substrate films (PET film S46 (12μm), POLYPLEX) and (OPP film, P-2161 (20μm), Toyobo Co., Ltd.) using a simple color spreading machine (RI tester, manufactured by Toyosaka Seikou Co., Ltd.). The prints were then irradiated with an electron beam at a conveyor speed of 10m / min using an electron beam curing device (EC90, manufactured by Iwasaki Electric Co., Ltd.) (acceleration voltage 90kV, irradiation dose 30kGy) to obtain printed materials with an ink-cured film. A dry laminating machine was used with adhesive (Takelac A969V / Takenate A-5), application rate: 3.0g / m². 2 A coating was applied, and a CPP film (L-4104, manufactured by Toyobo Co., Ltd., also called sealant, see Tables 4 to 7) was laminated to obtain a laminated product. The product was then held at 40°C for 3 days to obtain a film laminate of sealant / adhesive / ink-cured film / substrate.

[0077] For each of the resulting laminated materials, the laminate strength (peel strength) and seal strength were measured using the following method. The results for peel strength are shown in Tables 4-5, and the results for seal strength are shown in Tables 6-7.

[0078] (Laminate strength (peel strength)) Apply adhesive (Takelac A969V / Takenate A-5) to the printed surface at a rate of 3g / m² of solid content. 2 The material was applied in this manner, and the film was laminated using a dry laminating machine to obtain a laminate. It was then held at 40°C for 3 days. This laminate was cut into 15mm wide samples, and the T-shaped peel strength was measured using a peel tester manufactured by Yasuda Seiki Co., Ltd. The evaluation results are the measured strength values ​​(N / 15mm). The letters in the table indicate the location of the peel interface, etc. B indicates base / ink peeling, S indicates ink / sealant peeling, F indicates film rupture, and C indicates ink aggregation.

[0079] (Seal strength test) The above laminate was cut to a width of 15 mm x length of 100 mm, folded with the sealant film side facing inward to a width of 15 mm x length of 50 mm, and sealed using an impulse sealer (manufactured by Fuji Impulse Co., Ltd., seal width 10 mm) so that the center was 25 mm from the edge, to create a test specimen for seal strength testing. The test specimen was mounted on a peel tester (manufactured by Yasuda Seiki Co., Ltd.), and the strength (seal strength) was measured when it was broken at a peel speed of 300 mm / min. The evaluation results are the measured strength values ​​(N / 15 mm). The letters in the table indicate the position of the peel interface, etc. B is base / ink peeling, S is ink / sealant peeling, F is film breakage, and C is ink aggregation.

[0080] [Table 4]

[0081] [Table 5]

[0082] [Table 6]

[0083] [Table 7]

[0084] As shown in Tables 4 to 7, when the ink compositions of Examples 1 to 21 of the present invention were used, excellent lamination strength (peel strength) and seal strength were observed.

Claims

1. It contains an active energy ray polymerizable compound having a (meth)acryloyl group, The concentration of the (meth)acryloyl group is 2.2 to 4.5 mol / g. The glass transition temperature of the polymer obtained by polymerizing the aforementioned active energy ray polymerizable compound is -20°C to 25°C. The active energy ray polymerizable compound having a (meth)acryloyl group comprises a resin having a (meth)acryloyl group and a polyfunctional (meth)acrylate having a skeleton derived from alkylene oxide. The resin having (meth)acryloyl groups includes urethane acrylate resin, The urethane acrylate resin is an active energy ray curable offset printing ink composition containing an aliphatic urethane acrylate resin.

2. Furthermore, the active energy ray curable offset printing ink composition according to claim 1, comprising a coloring agent.

3. Furthermore, the active energy ray curable offset printing ink composition according to claim 1 or 2, further comprising an extender pigment.

4. Furthermore, the active energy ray curable offset printing ink composition according to claim 1 or 2 further comprises a metal chelating crosslinking agent.

5. The active energy ray curable offset printing ink composition according to claim 1 or 2, wherein the acid value of the urethane acrylate resin is 3 mg KOH / g or less.

6. The active energy ray curable offset printing ink composition according to claim 1 or 2, wherein the polyfunctional (meth)acrylate having an alkylene oxide-derived skeleton includes an alkylate oxide-modified polyfunctional (meth)acrylate containing 6 to 30 alkylene oxide units in the molecule.

7. The printed layer comprises a printed layer to which the active energy ray curable offset printing ink composition according to claim 1 or 2 is applied, The printing layer is provided on the first substrate, A laminate in which a second substrate is provided on the aforementioned printed layer.

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