Active energy ray curable inkjet ink for beverage containers, active energy ray curable inkjet ink set, and image recording method

Abstract

Provided are an active energy ray-curable inkjet ink for a beverage container and an application thereof, the inkjet ink containing a polymerizable monomer and a polymerizable surfactant. Also provided are an active energy ray-curable inkjet ink set and an application thereof, the inkjet ink set including: a first ink that contains a polyfunctional monomer; and a second ink that contains a monofunctional monomer, wherein at least one of the first ink and the second ink contains a polymerizable surfactant.

Description

[Technical Field]

[0001] This disclosure relates to an active energy ray curable inkjet ink for beverage containers, an active energy ray curable inkjet ink set, and an image recording method. [Background technology]

[0002] Conventionally, when recording an image on a substrate using ink, a method of curing it using active energy rays is known.

[0003] For example, Japanese Patent Publication No. 2013-514904 describes a radiation-curable inkjet ink set comprising at least first and second radiation-curable inkjet inks having a surface life of 50 ms and a dynamic surface tension of 30 mN / m or less, as measured by the maximum bubble pressure surface tension measurement method at 25°C.

[0004] International Publication No. 2018 / 139658 describes an active light-curable ink composition comprising a di(meth)acrylate having a linear alkylene group, a di(meth)acrylate having an alkylene oxide chain, a specific cyclohexyldienone-based polymerization inhibitor, and a photopolymerization initiator.

[0005] Japanese Patent Publication No. 2013-184453 describes an ultraviolet-curable image recording composition comprising an ultraviolet-curable substance, a water-absorbing component, and a reactive silicone-based surfactant having an HLB of 9 or more and less than 15 and reacting to ultraviolet light.

[0006] Japanese Patent Publication No. 2013-511584 describes a radiation-curable ink containing a curable silicone polyester acrylate surfactant in an amount ranging from approximately 0.0005 wt% to approximately 0.005 wt% of the total weight of the ink. [Overview of the project] [Problems that the invention aims to solve]

[0007] In image recordings obtained by applying ink to a substrate, it is sometimes necessary to immerse the image recording in a processing solution to peel the image from the substrate and then make the image separable. Furthermore, in image recording materials obtained by applying ink to a substrate, there are cases where it is necessary to make the image easier to peel off by immersion in an alkaline solution and to improve water resistance.

[0008] This disclosure has been made in view of these circumstances, and according to one embodiment of the present invention, an active energy ray curable inkjet ink for beverage containers that has excellent image separation from a substrate, an active energy ray curable inkjet ink set, and an image recording method are provided. Furthermore, according to another embodiment of the present invention, an active energy ray curable inkjet ink set is provided that exhibits excellent alkali peelability of images from a substrate and excellent water resistance. [Means for solving the problem]

[0009] This disclosure includes the following aspects: <1> An active energy ray curable inkjet ink for beverage containers, comprising a polymerizable monomer and a polymerizable surfactant. <2> The polymerizable monomers include polyfunctional monomers, and the polyfunctional monomer content is 25% by mass or more of the total amount of the active energy ray curable inkjet ink for beverage containers. <1> The activated energy ray curing inkjet ink for beverage containers described above. <3> The mass ratio of polyfunctional monomer content to polymerizable surfactant content is 4 to 80. <2> The activated energy ray curing inkjet ink for beverage containers described above. <4> The polymerizable monomers include monofunctional monomers, and the content of monofunctional monomers is 60% by mass or more of the total amount of the active energy ray curable inkjet ink for beverage containers. <1> The activated energy ray curing inkjet ink for beverage containers described above. <5> The mass ratio of the content of the monofunctional monomer to the content of the polymeric surfactant is 3 to 100, and the active energy ray-curable inkjet ink for beverage containers according to <4>. <6> The polymeric monomer includes a polymeric monomer having an acid group, and the active energy ray-curable inkjet ink for beverage containers according to any one of <1> to <5>. <7> The mass ratio of the content of the polymeric monomer having an acid group to the content of the polymeric surfactant is 0.2 to 10, and the active energy ray-curable ink for beverage containers according to <6>. Jet ink. <8> The polymeric monomer includes a polymeric monomer having a specific gravity of 1.0 or less, and the active energy ray-curable inkjet ink for beverage containers according to any one of <1> to <7>. <9> The polymeric surfactant is a silicone-based surfactant having a (meth)acryloyl group, and the active energy ray-curable inkjet ink for beverage containers according to any one of <1> to <8>. <10> The polymeric surfactant is a compound having a surface tension reduction degree of 5 mN / m or more with respect to cyclic trimethylolpropane formal acrylate, and the active energy ray-curable inkjet ink for beverage containers according to any one of <1> to <9>. <11> The polymeric surfactant includes a polymeric surfactant A having a logP value of 4 or more and a polymeric surfactant B having a logP value of less than 4, and the active energy ray-curable inkjet ink for beverage containers according to any one of <1> to <10>. <12> An active energy ray-curable inkjet ink set including a first ink containing a polyfunctional monomer and a second ink containing a monofunctional monomer, wherein at least one of the first ink and the second ink contains a polymeric surfactant. <13> An active energy ray-curable inkjet ink set including a first ink containing a polyfunctional monomer and a second ink containing a monofunctional monomer, wherein both the first ink and the second ink contain a polymeric surfactant, according to <12>. <14> At least one of the first ink and the second ink is an active energy ray-curable inkjet ink set according to <12> or <13>, wherein the polymerizable surfactant contains a polymerizable surfactant A having a logP value of 4 or more and a polymerizable surfactant B having a logP value of less than 4. <15> The active energy ray-curable inkjet ink set according to any one of <12> to <14>, wherein the content of the polyfunctional monomer in the first ink is 25% by mass or more based on the total amount of the first ink. <16> The active energy ray-curable inkjet ink set according to any one of <12> to <15>, wherein the first ink contains a polymerizable surfactant, and the mass ratio of the content of the polyfunctional monomer to the content of the polymerizable surfactant in the first ink is 4 to 80. <17> The active energy ray-curable inkjet ink set according to any one of <12> to <16>, wherein the first ink contains a polymerizable monomer having a specific gravity of 1.0 or less. <18> The active energy ray-curable inkjet ink set according to any one of <12> to <17>, wherein the content of the monofunctional monomer in the second ink is 60% by mass or more based on the total amount of the second ink. <19> The active energy ray-curable inkjet ink set according to any one of <12> to <18>, wherein the second ink contains a polymerizable surfactant, and the mass ratio of the content of the monofunctional monomer to the content of the polymerizable surfactant in the second ink is 3 to 100. <20> The active energy ray-curable inkjet ink set according to any one of <12> to <19>, wherein when the first ink and the second ink have the same mass, the mass ratio of the total content of the polyfunctional monomers in the first ink and the second ink to the content of the monofunctional monomer in the second ink is 0.2 to 0.9. <21> Both the first ink and the second ink contain polymerizable surfactants, and when the first ink and the second ink are of equal mass, the mass ratio of the polymerizable surfactant content in the second ink to the polymerizable surfactant content in the first ink is between 2 and 11. <12> ~ <20> An active energy ray curing inkjet ink set as described in one of the following. <22> The surface tension of the second ink is higher than that of the first ink. <12> ~ <21> An active energy ray curing inkjet ink set as described in one of the following. <23> The second ink contains a polymerizable monomer having an acid group. <12> ~ <22> An active energy ray curing inkjet ink set as described in one of the following. <24> When the first ink and the second ink are of equal mass, the mass ratio of the polymerizable monomers containing acidic groups in the second ink to the total monofunctional monomer content in the first and second inks is 0.05 to 0.1. <23> The activated energy ray curing inkjet ink set described above. <25> On the surface of the beverage container, <1> ~ <11> An image recording method comprising the steps of: applying an active energy ray-curable inkjet ink for beverage containers, as described in any one of the above, using an inkjet recording method; and irradiating the applied ink with active energy rays. <26> <12> ~ <24> An image recording method comprising the steps of: using an active energy ray curable inkjet ink set described in any one of the above, applying a first ink and a second ink onto a substrate using an inkjet recording method; and irradiating with an active energy ray after the first ink and the second ink have been applied, respectively. <27> An active energy ray-curable inkjet ink comprising a polymerizable monomer and a polymerizable surfactant, wherein the polymerizable monomer includes a monofunctional monomer, and the content of the monofunctional monomer is 60% by mass or more of the total amount of the active energy ray-curable inkjet ink. <28> Active energy ray curable inkjet ink set comprising a first ink containing a colorant and a polymerizable monomer having a hydroxyl group, and a second ink containing a polymerizable monomer having an acid group. <29> The content of polymerizable monomers having hydroxyl groups is 30% to 70% by mass relative to the total amount of the first ink. <28> The activated energy ray curing inkjet ink set described above. <30> The content of polymerizable monomers having acidic groups is 5% to 25% by mass relative to the total amount of the second ink. <28> or <29> The activated energy ray curing inkjet ink set described above. <31> The second ink further comprises a polymerizable monomer having a hydroxyl group. <28> ~ <30> An active energy ray curing inkjet ink set as described in one of the following. <32> In the second ink, the total content of polymerizable monomers having acidic groups and polymerizable monomers having hydroxyl groups is 10% to 50% by mass relative to the total amount of the second ink. <31> The activated energy ray curing inkjet ink set described above. <33> When the first ink and the second ink are of equal mass, the mass ratio of the hydroxyl-group polymerizable monomer content in the first ink to the total content of acid-group polymerizable monomers and hydroxyl-group polymerizable monomers in the second ink is 1 to 4. <31> or <32> The activated energy ray curing inkjet ink set described above. [Effects of the Invention]

[0010] According to one embodiment of the present invention, an active energy ray-curable inkjet ink for beverage containers that exhibits excellent image separation from a substrate, an active energy ray-curable inkjet ink set, and an image recording method are provided. Furthermore, according to another embodiment of the present invention, an active energy ray curable inkjet ink set is provided that exhibits excellent alkali peelability of images from a substrate and excellent water resistance. [Modes for carrying out the invention]

[0011] The following describes in detail the active energy ray curable inkjet ink for beverage containers, the active energy ray curable inkjet ink set, and the image recording method of this disclosure.

[0012] In this specification, a numerical range indicated using "~" means a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described stepwise in this specification, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Furthermore, in the numerical ranges described in this specification, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples.

[0013] In this specification, the amount of each component in a composition means the total amount of multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, provided that the intended purpose of the process is achieved.

[0014] In this specification, "image" means any film formed by applying ink, and "image recording" means the formation of an image (i.e., a film). Furthermore, the concept of "image" as used herein also includes solid images.

[0015] In this specification, "(meth)acrylate" is a concept that encompasses both acrylate and methacrylate. Similarly, "(meth)acrylic" is a concept that encompasses both acrylic and methacrylic.

[0016] An active energy ray curable inkjet ink for beverage containers (hereinafter also simply referred to as "ink"), which is one embodiment of the present disclosure, comprises a polymerizable monomer and a polymerizable surfactant.

[0017] An image recording can be obtained in which an ink film is formed as an image on a substrate by, for example, applying an ink according to one embodiment of the present disclosure to a substrate and then irradiating it with active energy rays. Since the ink according to one embodiment of the present disclosure contains a polymerizable monomer and a polymerizable surfactant, a polymerization reaction proceeds upon irradiation with active energy rays. Because the ink according to one embodiment of the present disclosure contains a polymerizable surfactant, the ink film formed by the polymerization reaction is considered to have surfactant properties. For example, when an image recording is immersed in a processing solution (for example, an alkaline aqueous solution), the adhesion between the substrate and the ink film decreases, and the ink film peels off the substrate. Because the ink film formed by the ink according to one embodiment of the present disclosure has surfactant properties, it is easily suspended after peeling off the substrate and has excellent separation properties.

[0018] In particular, the ink according to one embodiment of the present disclosure is suitable for recording images on the surface of beverage containers. For example, in a recycling system, beverage containers such as PET bottles are subjected to crushing and grinding processes, and then separated into crushed beverage container material with a high specific gravity and crushed lid material with a low specific gravity by a specific gravity separation method. This separation is performed, for example, by immersing the beverage containers in a processing liquid (e.g., an alkaline aqueous solution). As described above, the ink film formed with the ink according to one embodiment of the present disclosure has excellent separation properties. Therefore, when an image is recorded on a beverage container using the ink according to one embodiment of the present disclosure, the image can be easily separated from the beverage container.

[0019] On the other hand, the conventional inks described in Japanese Patent Publication No. 2013-514904, International Publication No. 2018 / 139658, Japanese Patent Application Publication No. 2013-184453, and Japanese Patent Publication No. 2013-511584 are not intended for use in beverage containers.

[0020] Furthermore, another embodiment of the present disclosure, an active energy ray curable inkjet ink set, comprises a first ink containing a polyfunctional monomer and a second ink containing a monofunctional monomer, wherein at least one of the first ink and the second ink contains a polymerizable surfactant. Hereinafter, an ink set comprising a first ink containing a polyfunctional monomer and a second ink containing a monofunctional monomer, wherein at least one of the first ink and the second ink contains a polymerizable surfactant, will be referred to as "ink set A".

[0021] Using ink set A, which is another embodiment of the present disclosure, an image recording can be obtained in which an ink film is formed as an image on the substrate by, for example, applying a first ink and a second ink to a substrate and then irradiating it with active energy rays. In ink set A, which is another embodiment of the present disclosure, the first ink contains a polyfunctional monomer, the second ink contains a monofunctional monomer, and at least one of the first ink and the second ink contains a polymerizable surfactant, so a polymerization reaction proceeds when irradiated with active energy rays. Since at least one of the first ink and the second ink contains a polymerizable surfactant, the ink film formed by the polymerization reaction is considered to have surfactant properties. For example, when an image recording is immersed in a processing solution (e.g., an alkaline aqueous solution), the adhesion between the substrate and the ink film decreases, and the ink film peels off the substrate. Since the ink film formed by ink set A, which is another embodiment of the present disclosure, has surfactant properties, it is easy to float after peeling off the substrate and has excellent separation properties.

[0022] Furthermore, an ink set in yet another embodiment of the present disclosure comprises a first ink containing a colorant and a polymerizable monomer having a hydroxyl group, and a second ink containing a polymerizable monomer having an acid group. Hereinafter, an ink set comprising a first ink containing a colorant and a polymerizable monomer having a hydroxyl group, and a second ink containing a polymerizable monomer having an acid group will be referred to as "Ink Set B".

[0023] Using ink set B, which is yet another embodiment of the present disclosure, an image recording can be obtained in which an ink film is formed as an image on the substrate by, for example, applying a first ink and a second ink to a substrate and then irradiating it with an active energy ray. In ink set B, since the first ink contains a polymerizable monomer having a hydroxyl group, an alkaline aqueous solution easily penetrates into the ink film. Also, since the second ink contains a polymerizable monomer having an acid group, when an alkaline aqueous solution penetrates into the ink film, the acid group reacts with the alkali to form a salt, improving the water solubility of the ink film. Therefore, when the image recording is immersed in an alkaline aqueous solution, the ink film is easily peeled off the substrate. Also, when the image recording is immersed in water, curing shrinkage is suppressed, and the image is less likely to peel off the substrate due to water. In other words, the image recording obtained using ink set B, which is yet another embodiment of the present disclosure, has excellent alkali peelability and water resistance.

[0024] On the other hand, the conventional ink sets described in Japanese Patent Publication No. 2013-514904 all contain polyfunctional monomers that are polymerizable monomers. Furthermore, International Publication No. 2018 / 139658, Japanese Patent Publication No. 2013-184453, and Japanese Patent Publication No. 2013-511584 do not contain any descriptions regarding ink sets.

[0025] The following describes each component contained in the ink, which is one embodiment of this disclosure.

[0026] [Activated energy ray curing inkjet ink for beverage containers] An ink, which is one embodiment of the present disclosure, comprises a polymerizable monomer and a polymerizable surfactant.

[0027] One embodiment of the present disclosure is an ink for beverage containers. Specifically, the ink is used to record an image on the surface of a beverage container. The material of the beverage container is not particularly limited and includes, for example, glass and plastic. In particular, the ink of one embodiment of the present disclosure is preferably for plastic beverage containers, and more preferably for PET bottles containing polyethylene terephthalate as the main component.

[0028] One embodiment of the present disclosure is an active energy ray curable ink. That is, the ink according to one embodiment of the present disclosure is cured by irradiation with active energy rays. Examples of active energy rays include gamma rays, beta rays, electron beams, ultraviolet rays, and visible light. Among these, ultraviolet rays are preferred as the active energy ray. The ink according to one embodiment of the present disclosure is preferably an ultraviolet-curable ink.

[0029] <polymerizable surfactants> An ink according to one embodiment of the present disclosure contains a polymerizable surfactant. The polymerizable surfactant may be present in the ink alone or in two or more types.

[0030] In this disclosure, "polymerizable surfactant" means a surfactant having polymerizable groups. In this disclosure, "surfactant" means a compound that, when added at an amount of 0.5% by mass to cyclic trimethylolpropane formal acrylate (hereinafter referred to as "CTFA"), reduces the surface tension by 1 mN / m or more. The surface tension is measured using a surface tensimeter by the plate method at 25°C, and can be measured using, for example, an automatic surface tensimeter (product name "DY-300") manufactured by Kyowa Interface Science Co., Ltd. The surface tension of CTFA is 36.5 mN / m.

[0031] The polymerizable group in a polymerizable surfactant may be a cationic polymerizable group or a radical polymerizable group, but from the viewpoint of curability, a radical polymerizable group is preferable. Furthermore, from the viewpoint of curability, the radical polymerizable group is preferably an ethylenically unsaturated group. Among these, the polymerizable group in a polymerizable surfactant is preferably a vinyl group or a (meth)acryloyl group, and from the viewpoint of ethanol resistance, a (meth)acryloyl group is more preferable.

[0032] From the viewpoint of separation properties, it is preferable for polymerizable surfactants to have two or more polymerizable groups. It is preferable that the number be 3 or more. There is no particular upper limit to the number of polymerizable groups in a polymerizable surfactant, but from the viewpoint of ejection performance when ejecting ink in an inkjet recording method, it is, for example, 5.

[0033] In other words, with respect to the type and number of polymerizable groups, polymerizable surfactants are preferably surfactants having two or more (meth)acryloyl groups, and more preferably surfactants having three or more (meth)acryloyl groups.

[0034] Examples of polymerizable surfactants include polymerizable silicone-based surfactants, polymerizable fluorine-based surfactants, and polymerizable acrylic-based surfactants.

[0035] Examples of polymerizable silicone-based surfactants include compounds in which polymerizable groups are bonded to the main chain or side chain of a polyether-modified dimethylsiloxane.

[0036] Examples of commercially available polymerizable silicone-based surfactants include BYK-UV3500, 3505, 3530, 3570, 3575, 3576 (manufactured by BYK), Tegorad2100, 2200, 2250, 2300, 2500, 2600, 2700, 2800, 2010, 2011 (manufactured by Evonik), EBECRYL350, 1360 (manufactured by Daicel Ornex), and KP-410, 411, 412, 413, 414, 415, 416, 418, 420, 422, 423 (manufactured by Shin-Etsu Silicone Co., Ltd.), which are silicone-based surfactants having (meth)acryloyl groups.

[0037] Examples of polymerizable fluorine-based surfactants include compounds having a perfluoroalkyl group and a polymerizable group.

[0038] Examples of commercially available polymerizable fluorinated surfactants include fluorinated surfactants having a (meth)acryloyl group, such as Megafac RS-56, RS-72-K, RS-75, RS-76-E, RS-65-NS, RS-78, and RS-90 (manufactured by DIC Corporation).

[0039] Examples of polymerizable acrylic surfactants include compounds in which polymerizable groups are bonded to the side chains of a poly(meth)acrylic structure.

[0040] A commercially available polymerizable acrylic surfactant is, for example, CN821 (manufactured by Sartomer).

[0041] In particular, polymerizable surfactants are preferably compounds that have a high effect in reducing surface tension from the viewpoint of separation. Specifically, when the degree of surface tension reduction is defined as follows, polymerizable surfactants are preferably compounds that have a degree of surface tension reduction of 5 mN / m or more relative to CTFA, and more preferably compounds that have a degree of surface tension reduction of 10 mN / m or more relative to CTFA. The upper limit of the degree of surface tension reduction relative to CTFA is not particularly limited, but from the viewpoint of ink discharge performance, it is preferably 17 mN / m. The degree of reduction in surface tension relative to CTFA = (Surface tension of CTFA) - (Surface tension when surfactant is added at an amount of 0.5% by mass relative to CTFA) The surface tension of CTFA is 36.5 mN / m.

[0042] In other words, the polymerizable surfactant is preferably a compound that, when added at an amount of 0.5% by mass relative to CTFA, has a surface tension of 31.5 mN / m or less, and more preferably a compound that has a surface tension of 26.5 mN / m or less.

[0043] Below, each commercially available surfactant is added to CTFA at an amount of 0.5% by mass. The results of measuring the surface tension in the following cases are shown. For products where the surfactant content is not 100% by mass (for example, products containing solvents in addition to surfactants), the product was prepared so that the surfactant content was 100% by mass, and the surface tension was measured using the surfactant alone. For reference, the results of measurements using both polymerizable and non-polymerizable surfactants are also shown. "Non-polymerizable" means that it does not have polymerizable groups.

[0044] - Polymerizable silicone-based surfactants - BYK-UV3500: 23.9 mN / m BYK-UV3505: 23.6 mN / m BYK-UV3530: 33.3 mN / m BYK-UV3570: 24.9 mN / m BYK-UV3575: 24.3 mN / m BYK-UV3576: 32.7 mN / m Tegorad2100: 27.5 mN / m Tegorad2200: 24.5 mN / m Tegorad2250: 23.3 mN / m Tegorad2300: 22.9 mN / m Tegorad2500: 21.9 mN / m Tegorad2650: 21.4 mN / m Tegorad2700: 21.3 mN / m Tegorad2800: 21.2 mN / m Tegorad2010: 21.9 mN / m Tegorad2011: 29.8 mN / m KP-423: 21.6 mN / m -Polymerizable fluorine-based surfactant- Megafuck RS-56: 22.1 mN / m Megafuck RS-72-K: 22.5 mN / m Megafuck RS-75: 22.3 mN / m Megafuck RS-76-E: 22.7 mN / m Megafuck RS-76-NS: 22.1 mN / m Megafuck RS-78: 22.3 mN / m Megafuck RS-90: 22.7 mN / m -Polymerizable acrylic surfactant- CN821: 34.1 mN / m -Non-polymerizable silicone-based surfactant- BYK306: 22.2 mN / m BYK-UV3510: 23.8 mN / m -Non-polymerizable fluorine-based surfactant- Megafuck F554: 25.4 mN / m -Non-polymerizable acrylic surfactant- BYK361N: 34.6 mN / m

[0045] From the viewpoint of separation properties, the polymerizable surfactant is preferably a polymerizable fluorine-based surfactant or a polymerizable silicone-based surfactant, and more preferably a polymerizable silicone-based surfactant. Furthermore, from the viewpoint of improving ethanol resistance, the polymerizable surfactant is more preferably a silicone-based surfactant having a (meth)acryloyl group.

[0046] The molecular weight of the polymerizable surfactant is preferably between 1,000 and 20,000.

[0047] In this disclosure, polymerizable surfactant is polymerizable surfactant A with a logP value of 4 or higher, It is preferable to include polymerizable surfactant B with a logP value of less than 4. Polymerizable surfactant A with a logP value of 4 or more and polymerizable surfactant B with a logP value of less than 4 may each be included in the ink individually or in two or more types.

[0048] A logP value of 4 or higher indicates relatively high hydrophobicity. A logP value of less than 4 indicates relatively high hydrophilicity. When polymerizable surfactant A is included in the ink, the ink film formed by the application of the ink becomes hydrophobic, improving water repellency. This makes the ink film easier to float and improves separation. On the other hand, polymerizable surfactant A tends to be poorly soluble in ink, but when used in combination with polymerizable surfactant B, polymerizable surfactant B increases the solubility of polymerizable surfactant A in the ink, resulting in an image with suppressed ink repellency. "Ink repellency" is a phenomenon that occurs when ink hardens while areas of the ink are repelled from the substrate.

[0049] From the viewpoint of further improving separation performance and further suppressing image repulsion, the difference between the logP value of polymerizable surfactant A and the logP value of polymerizable surfactant B (i.e., "logP value of polymerizable surfactant A - logP value of polymerizable surfactant B") is preferably 2 to 4.

[0050] Furthermore, from the viewpoint of further improving separation performance and further suppressing image repulsion, the mass ratio of polymerizable surfactant B to polymerizable surfactant A is preferably 1.1 to 15, and more preferably 2 to 8.

[0051] The logP values ​​for polymerizable surfactants are specified in JIS Z 7260-117:2006. It is a value measured by a corresponding method.

[0052] The content of polymerizable surfactant is preferably 0.05% to 25% by mass, and more preferably 0.1% to 20% by mass, relative to the total amount of ink. The content of polymerizable surfactant is preferably adjusted by the content of polymerizable monomer.

[0053] <Polymerizable monomers> An ink according to one embodiment of the present disclosure comprises a polymerizable monomer. The polymerizable monomer may be present in the ink alone or in two or more types.

[0054] In this disclosure, "monomer" means a compound with a molecular weight of less than 1000. The molecular weight can be calculated from the types and number of elements that make up the compound. In this disclosure, "polymerizable monomer" means a monomer having a polymerizable group.

[0055] The polymerizable group in a polymerizable monomer may be either a cationic polymerizable group or a radical polymerizable group, but from the viewpoint of curability, a radical polymerizable group is preferable. Furthermore, from the viewpoint of curability, the radical polymerizable group is preferably an ethylenically unsaturated group.

[0056] The polymerizable monomer may be a monofunctional monomer having one polymerizable group, or a polyfunctional monomer having two or more polymerizable groups.

[0057] -Monofunctional monomers- The monofunctional monomer is not particularly limited as long as it is a monomer having one polymerizable group. From the viewpoint of curability, the monofunctional monomer is preferably a monofunctional radical polymerizable monomer, and more preferably a monofunctional ethylenically unsaturated monomer.

[0058] Examples of monofunctional ethylenically unsaturated monomers include monofunctional (meth)acrylates, mono Examples include functional (meth)acrylamides, monofunctional aromatic vinyl compounds, monofunctional vinyl ethers, and monofunctional N-vinyl compounds.

[0059] Examples of monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, tert-octyl (meth)acrylate, isoamyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate. 4-n-butylcyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, 2-ethylhexyl diglycol (meth)acrylate, butoxyethyl (meth)acrylate, 2-chloroethyl (meth)acrylate, 4-bromobutyl (meth)acrylate, cyanoethyl (meth)acrylate, benzyl (meth)acrylate, butoxymethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-(2-methoxymethyl (Thiethoxy)ethyl (meth)acrylate, 2-(2-butoxyethoxy)ethyl (meth)acrylate, 2,2,2-tetrafluoroethyl (meth)acrylate, 1H,1H,2H,2H-perfluorodecyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4,5-tetramethylphenyl (meth)acrylate, 4-chlorophenyl (meth)acrylate, 2-phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, glycidyl (meth)acrylate Glycidyloxybutyl (meth)acrylate, glycidyloxyethyl (meth)acrylate, glycidyloxypropyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclic trimethylolpropaneformal (meth)acrylate,Phenylglycidyl ether (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, trimethylsilylpropyl (meth)acrylate, polyethylene oxide monomethyl ether (meth)acrylate, polyethylene oxide (meth)acrylate, polyethylene oxide monoalkyl ether (meth)acrylate, dipropylene glycol (meth)acrylate, polypropylene oxide monoalkyl ether (meth)acrylate, 2-methacryloyloxyethyl succinate, 2-methacryloyloxyhexahydrophthalate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, ethoxydiethylene glycol (meth)acrylate, butoxydi Examples include ethylene glycol (meth)acrylate, trifluoroethyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, ethylene oxide (EO)-modified phenol (meth)acrylate, EO-modified cresol (meth)acrylate, EO-modified nonylphenol (meth)acrylate, propylene oxide (PO)-modified nonylphenol (meth)acrylate, EO-modified 2-ethylhexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, (3-ethyl-3-oxetanylmethyl) (meth)acrylate, phenoxyethylene glycol (meth)acrylate, 2-carboxyethyl (meth)acrylate, and 2-(meth)acryloyloxyethyl succinate.

[0060] Examples of monofunctional (meth)acrylamides include (meth)acrylamide, N-methyl Examples include N-(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, Nn-butyl(meth)acrylamide, Nt-butyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-methylol(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, and (meth)acryloylmorpholin.

[0061] Examples of monofunctional aromatic vinyl compounds include styrene, dimethylstyrene, trimethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, methyl vinylbenzoate, 3-methylstyrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4-hexylstyrene, 3-octylstyrene, 4-octylstyrene, 3-(2-ethylhexyl)styrene, 4-(2-ethylhexyl)styrene, allylstyrene, isopropenylstyrene, butenylstyrene, octenylstyrene, 4-t-butoxycarbonylstyrene, and 4-t-butoxystyrene.

[0062] Examples of monofunctional vinyl ethers include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, cyclohexylmethyl vinyl ether, 4-methylcyclohexylmethyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexylmethyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, and phenoxypolyethylene glycol vinyl ether.

[0063] Examples of monofunctional N-vinyl compounds include N-vinyl-ε-caprolactam and N-vinylpyrrolidone.

[0064] -Polyfunctional monomer- The polyfunctional monomer is not particularly limited as long as it is a monomer having two or more polymerizable groups. From the viewpoint of curability, the polyfunctional monomer is preferably a polyfunctional radical polymerizable monomer, and more preferably a polyfunctional ethylenically unsaturated monomer.

[0065] Examples of polyfunctional ethylenically unsaturated monomers include polyfunctional (meth)acrylate compounds and polyfunctional vinyl ethers.

[0066] Examples of polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate. Relate, butylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, hexanediol di(meth)acrylate, heptanediol di(meth)acrylate, EO-modified neopentyl glycol di(meth)acrylate, PO-modified neopentyl glycol di(meth)acrylate, EO-modified hexanediol di(meth)acrylate, PO-modified hexanediol di(meth)acrylate, octanediol di(meth)acrylate, nonanediol di(meth)acrylate, decanediol di(meth)acrylate, dodecanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate Examples include ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane EO-added tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, glycerin polyglycidyl ether poly(meth)acrylate, and tris(2-acryloyloxyethyl) isocyanurate.

[0067] Examples of polyfunctional vinyl ethers include 1,4-butanediol divinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, and ditrimethylolpropane. Examples include trivinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexanyl ether, EO-added trimethylolpropane trivinyl ether, PO-added trimethylolpropane trivinyl ether, EO-added ditrimethylolpropane tetravinyl ether, PO-added ditrimethylolpropane tetravinyl ether, EO-added pentaerythritol tetravinyl ether, PO-added pentaerythritol tetravinyl ether, EO-added dipentaerythritol hexanyl ether, and PO-added dipentaerythritol hexanyl ether.

[0068] In particular, the polymerizable monomers preferably include polymerizable monomers with a specific gravity of 1.0 or less. Examples of polymerizable monomers with a specific gravity of 1.0 or less include the following compounds. n-Octyl acrylate: 0.894 g / cm³ 3 Nonyl acrylate: 0.875 g / cm³ 3 • Isononyl acrylate: 0.885 g / cm³ 3 Isodecyl acrylate: 0.88 g / cm³ 3 • Lauryl acrylate: 0.875 g / cm³ 3 · Isostearyl acrylate: 0.871 g / cm 3 · Stearyl acrylate: 0.86 g / cm 3 · Tricyclohexyl acrylate: 0.93 g / cm 3 · t-Butylcyclohexyl acrylate: 0.941 g / cm 3 · Cyclohexyl acrylate: 0.98 g / cm 3 · Isobornyl acrylate: 0.987 g / cm 3 · N-Isopropylacrylamide: 0.89 g / cm 3 · N,N-Dimethylacrylamide: 0.964 g / cm 3 · Decanediol diacrylate: 0.968 g / cm 3 · Triethylene glycol divinyl ether: 1.00 g / cm 3

[0069] When the ink contains a polymerizable monomer having a specific gravity of 1.0 or less, the ink film formed by the application of the ink becomes lighter and the separability is improved.

[0070] The mass ratio of the content of the polymerizable monomer having a specific gravity of more than 1.0 to the content of the polymerizable monomer having a specific gravity of 1.0 or less is preferably 0.1 to 10, and more preferably 0.5 to 7. When the above mass ratio is 0.1 or more, the adhesion is further improved. On the other hand, when the above mass ratio is 10 or less, the separability is improved.

[0071] In the present disclosure, the specific gravity is measured using a hydrometer, for example, measured using a high-precision electronic hydrometer (model number "EW-300SG", manufactured by Alpha Mirage Co., Ltd.).

[0072] (First Aspect) In a first embodiment of the ink, which is one embodiment of the present disclosure, the polymerizable monomer includes a polyfunctional monomer, and the content of the polyfunctional monomer is preferably 25% by mass or more, more preferably 30% by mass or more, and even more preferably 33% by mass or more, based on the total amount of ink. When the polyfunctional monomer content is 25% by mass or more, the image is easily peeled off from the substrate when the image recording material is immersed in an alkaline solution. In other words, it has excellent alkali peelability. When the ink contains a polyfunctional monomer, curing shrinkage occurs in the polymerization reaction caused by irradiation with active energy rays after the ink is applied, and residual stress is generated. When the polyfunctional monomer content is 25% by mass or more, the residual stress is large, and therefore it is considered to have excellent alkali peelability. Furthermore, when the polyfunctional monomer content is 25% by mass or more, a crosslinked structure is formed by the polymerization reaction, which improves ethanol resistance.

[0073] While there is no particular upper limit to the content of polyfunctional monomers, it is preferably 85% by mass from the viewpoint of adhesion.

[0074] -Polyfunctional monomers / polymerizable surfactants- The mass ratio of the polyfunctional monomer content to the polymerizable surfactant content is preferably 3 to 250, more preferably 4 to 200, even more preferably 4 to 80, particularly preferably 6 to 80, and most preferably 7 to 50. When the above mass ratio is 3 or higher, alkali peelability is improved. On the other hand, when the above mass ratio is 250 or lower, separation performance is improved.

[0075] In the first embodiment, the content of the polymerizable surfactant is preferably 0.05% to 25% by mass, more preferably 0.1% to 20% by mass, and even more preferably 0.1% to 10% by mass, based on the total amount of ink.

[0076] (Second aspect) In a second embodiment of the ink, which is one embodiment of the present disclosure, the polymerizable monomer includes a monofunctional monomer, and the content of the monofunctional monomer is preferably 60% or more, more preferably 65% ​​or more, and even more preferably 70% by mass or more, based on the total amount of ink. When the content of the monofunctional monomer is 70% by mass or more, the residual stress due to curing shrinkage is small, and thus the adhesion to the substrate is improved.

[0077] In the second embodiment, the content of the polymerizable surfactant is preferably 0.05% to 25% by mass, more preferably 0.1% to 20% by mass, even more preferably 1% to 20% by mass, and particularly preferably 5% to 20% by mass, based on the total amount of ink.

[0078] While there is no particular upper limit to the content of monofunctional monomers, it is preferably 95% by mass from the viewpoint of alkali exfoliation.

[0079] -Monofunctional monomers / polymerizable surfactants- The mass ratio of the monofunctional monomer content to the polymerizable surfactant content is preferably 2 to 1000, more preferably 2 to 400, even more preferably 5 to 100, and particularly preferably 7 to 40. When the above mass ratio is 2 or higher, adhesion to the substrate is improved. On the other hand, when the above mass ratio is 1000 or lower, separation is improved.

[0080] In a second embodiment of the ink, which is one embodiment of the present disclosure, the polymerizable monomer preferably includes a polymerizable monomer having an acid group.

[0081] Examples of acidic groups in polymerizable monomers containing acidic groups include carboxyl groups, sulfo groups, phosphonic acid groups, phosphoric acid groups, and sulfonamide groups.

[0082] Examples of polymerizable monomers having a carboxyl group include 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-carboxyethyl (meth)acrylate, and (meth)acrylic acid.

[0083] Examples of polymerizable monomers having a sulfo group include 2-hydroxy-3-sulfopropyl(meth)acrylate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, 2-sulfoethyl(meth)acrylate, 3-sulfopropyl(meth)acrylate, and 4-styrenesulfonic acid.

[0084] Examples of polymerizable monomers having a phosphate group include 2-phosphonooxyethyl (meth)acrylate and 2-(meth)acryloyloxyethyl acid phosphate.

[0085] In particular, polymerizable monomers having an acidic group are preferably polymerizable monomers having a carboxyl group.

[0086] The polymerizable monomer having an acidic group may be a monofunctional monomer having an acidic group, or a polyfunctional monomer having an acidic group, but it is preferably a monofunctional monomer having an acidic group, more preferably a monofunctional monomer having a carboxyl group, and even more preferably a monofunctional (meth)acrylate having a carboxyl group.

[0087] Acidic groups react with alkalis to form salts, which improves their water solubility. Therefore, if an ink contains polymerizable monomers with acidic groups, its alkali-removable properties improve.

[0088] When the ink contains polymerizable monomers having acidic groups, the content of polymerizable monomers having acidic groups is preferably 3% to 10% by mass of the total amount of ink. The content of polymerizable monomers having acidic groups is preferably adjusted by the content of polymerizable surfactants.

[0089] -Polymerizable monomers / polymerizable surfactants containing acidic groups- The mass ratio of polymerizable monomers having acidic groups to the polymerizable surfactant is preferably 0.1 to 30, more preferably 0.15 to 15, even more preferably 0.18 to 12, and particularly preferably 0.2 to 10. When the above mass ratio is 0.1 or higher, alkali peelability is improved. On the other hand, when the above mass ratio is 30 or lower, separation performance is improved.

[0090] <Polymerization initiator> An ink according to one embodiment of the present disclosure may contain at least one polymerization initiator. The polymerization initiator is preferably a radical polymerization initiator that generates radicals.

[0091] Examples of radical polymerization initiators include alkylphenone compounds, acylphosphine compounds, aromatic onium salt compounds, organic peroxides, thio compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having carbon-halogen bonds, and alkylamine compounds.

[0092] In particular, the polymerization initiator is preferably at least one selected from the group consisting of acylphosphine compounds and thio compounds, preferably at least one selected from the group consisting of acylphosphine oxide compounds and thioxanthone compounds, and more preferably a combination of acylphosphine oxide compounds and thioxanthone compounds.

[0093] Examples of acylphosphine oxide compounds include monoacylphosphine oxide compounds and bisacylphosphine oxide compounds, with bisacylphosphine oxide compounds being preferred.

[0094] Examples of monoacylphosphine oxide compounds include isobutyryldiphenylphosphine oxide, 2-ethylhexanoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, o-toluyldiphenylphosphine oxide, pt-butylbenzoyldiphenylphosphine oxide, 3-pyridylcarbonyldiphenylphosphine oxide, acryloyldiphenylphosphine oxide, benzoyldiphenylphosphine oxide, pivaloylphenylphosphine vinyl ester, and Examples include dipoylbisdiphenylphosphine oxide, pivaloyldiphenylphosphine oxide, p-toluyldiphenylphosphine oxide, 4-(t-butyl)benzoyldiphenylphosphine oxide, terephthaloylbisdiphenylphosphine oxide, 2-methylbenzoyldiphenylphosphine oxide, versatoyldiphenylphosphine oxide, 2-methyl-2-ethylhexanoyldiphenylphosphine oxide, 1-methylcyclohexanoyldiphenylphosphine oxide, methyl pivaloylphenylphosphinate, and isopropyl pivaloylphenylphosphinate.

[0095] Examples of bisacylphosphine oxide compounds include bis(2,6-dichlorobenzoyl)phenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-ethoxyphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2-naphthylphosphine oxide, and bis(2,6-dichlorobenzoyl) Bis(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-chlorophenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,4-dimethoxyphenylphosphine oxide, bis(2,6-dichlorobenzoyl)decylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-octylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2, 5-Dimethylphenylphosphine oxide, bis(2,6-dichloro-3,4,5-trimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,6-dichloro-3,4,5-trimethoxybenzoyl)-4-ethoxyphenylphosphine oxide, bis(2-methyl-1-naphthoyl)-2,5-dimethylphenylphosphine oxide, bis(2-methyl-1-naphthoyl)-4-ethoxyphenylphosphine oxide, bis(2-methyl-1-naphthoyl)-2- Examples include naphthylphosphine oxide, bis(2-methyl-1-naphthoyl)-4-propylphenylphosphine oxide, bis(2-methyl-1-naphthoyl)-2,5-dimethylphenylphosphine oxide, bis(2-methoxy-1-naphthoyl)-4-ethoxyphenylphosphine oxide, bis(2-chloro-1-naphthoyl)-2,5-dimethylphenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

[0096] Among these, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (product name "Omnirad 819") is preferred as an acylphosphine oxide compound.

[0097] Thioxanthone compounds include thioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 2-dodecylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone, 3-(2-methoxyethoxycarbonyl)thioxanthone, and 4-butoxycarbonyl Bonylthioxanthone, 3-butoxycarbonyl-7-methylthioxanthone, 1-cyano-3-chlorothioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone, 1-ethoxycarbonyl-3-aminothioxanthone, 1-ethoxycarbonyl-3-phenylsulfurylthioxanthone, 3,4-di[2-(2-methoxyethoxy)ethoxycarbonyl]thioxanthone, 1-E Toxycarbonyl-3-(1-methyl-1-morpholinoethyl)thioxanthone, 2-methyl-6-dimethoxymethylthioxanthone, 2-methyl-6-(1,1-dimethoxybenzyl)thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethylthioxanthone, n-allylthioxanthone-3,4-dicarboximide, n-octylthioxanthone-3,4-dicarboximide, N-(1,1,3,3-tetra Examples include methylbutyl)thioxanthone-3,4-dicarboximide, 1-phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, thioxanthone-2-polyethylene glycol ester, and 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthone-2-yloxy)-N,N,N-trimethyl-1-propaneaminium chloride.

[0098] Thioxanthone compounds may be commercially available. Examples of commercially available products include Lambson's SPEEDCURE series (e.g., SPEEDCURE 7010, SPEEDCURE CPTX, SPEEDCURE ITX, etc.).

[0099] From the viewpoint of improving the curability of the ink, the content of the polymerization initiator is preferably 2% by mass or more, and more preferably 5% by mass or more, relative to the total amount of ink. The upper limit of the polymerization initiator content is not particularly limited, but for example, it is 10% by mass.

[0100] <Polymerization inhibitors> An ink, which is one embodiment of the present disclosure, preferably contains at least one polymerization inhibitor.

[0101] Examples of polymerization inhibitors include hydroquinone compounds, phenothiazines, catechols, alkylphenols, alkylbisphenols, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionates, mercaptobenzimidazole, phosphates, nitrosamine compounds, hindered amine compounds, and nitroxyl radicals.

[0102] In particular, the polymerization inhibitor is more preferably a nitrosamine compound.

[0103] Examples of nitrosamine compounds include N-nitroso-N-phenylhydroxylamine aluminum salt and N-nitroso-N-phenylhydroxylamine. Among these, the nitrosamine compound is preferably N-nitroso-N-phenylhydroxylamine aluminum salt.

[0104] From the viewpoint of improving the long-term stability of the ink, the content of the polymerization inhibitor is preferably 0.05% to 0.5% by mass relative to the total amount of ink.

[0105] <Coloring agent> An ink, which is one embodiment of the present disclosure, may contain at least one colorant. Examples of colorants include dyes and pigments. From the viewpoint of durability such as heat resistance, light resistance, and water resistance, the colorant is preferably a pigment.

[0106] When pigments are used as colorants, they can be included in the ink as a pigment dispersion. A pigment dispersion is a liquid obtained by dispersing a pigment in a liquid medium using a dispersant, and it contains at least a pigment, a dispersant, and a liquid medium. Details of the dispersant will be described later. The liquid medium may be an organic solvent or a polymerizable monomer.

[0107] As pigments, either commercially available organic or inorganic pigments can be used. Examples of pigments include those described in "Dictionary of Pigments" edited by Seijiro Ito (published in 2000), "Industrial Organic Pigments" by W. Herbst and K. Hunger, and Japanese Patent Publication Nos. 2002-12607, 2002-188025, 2003-26978, and 2003-342503.

[0108] If the ink contains a colorant, the colorant content is preferably 0.5% to 15% by mass, more preferably 1% to 10% by mass, and even more preferably 2% to 5% by mass, based on the total amount of ink.

[0109] Furthermore, the ink in one embodiment of this disclosure may be a so-called clear ink that does not contain a colorant. Clear ink alone may be applied to the substrate to give it a glossy appearance. Clear ink may also be applied as a base coat (pre-coat liquid) when recording an image on the substrate, before applying the colored ink. Clear ink may also be applied as a top coat (overcoat liquid) when recording an image on the substrate, after applying the colored ink.

[0110] <Dispersant> When pigments are used as colorants, they can be included in the ink as a pigment dispersion. Pigments can also be dispersed in a liquid medium using a dispersant. Commonly known dispersants can be used. From the viewpoint of dispersion stability, the dispersant is preferably a compound that has both a hydrophilic and a hydrophobic structure.

[0111] Examples of dispersants include low molecular weight dispersants with a molecular weight of less than 1000, such as higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, naphthalene sulfonates, alkyl phosphates, polyoxyalkylene alkyl ether phosphates, polyoxyalkylene alkylphenyl ethers, polyoxyethylene polyoxypropylene glycol, glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene fatty acid amides, and amine oxides.

[0112] Furthermore, as a dispersant, a high molecular weight dispersant with a molecular weight of 1000 or more obtained by copolymerizing a hydrophilic monomer and a hydrophobic monomer is also mentioned. From the viewpoint of dispersion stability, the hydrophilic monomer is preferably a dissociable group-containing monomer, and more preferably a dissociable group-containing monomer having a dissociable group and an ethylenically unsaturated bond. Examples of dissociable group-containing monomers include carboxyl group-containing monomers, sulfonic acid group-containing monomers, and phosphate group-containing monomers. From the viewpoint of dispersion stability, the hydrophobic monomer is preferably an aromatic group-containing monomer having an aromatic group and an ethylenically unsaturated bond, or an aliphatic hydrocarbon group-containing monomer having an aliphatic hydrocarbon group and an ethylenically unsaturated bond. The polymer may be either a random copolymer or a block copolymer.

[0113] The dispersant may be a commercially available product. For example, DISPERBYK-101, DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-110, DISPERBYK-111, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-166, DISPERBYK-167, DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-182 (all manufactured by BYK Chemie); and SOLSPERSE3000, SOLSPERSE5000, SOLSPERSE9000, SOLSPERSE12000, SOLSPERSE13240, SOLSPERSE13940, SOLSPERSE17000, SOLSPERSE22000, SOLSPERSE24000, SOLSPERSE26000, SOLSPERSE28000, SOLSPERSE32000, SOLSPERSE36000, SOLSPERSE39000, SOLSPERSE41000, SOLSPERSE71000 (all manufactured by Lubrizol) These are some examples.

[0114] Known dispersion devices can be used to disperse pigments, including, for example, ball mills, sand mills, bead mills, roll mills, jet mills, paint shakers, attritors, ultrasonic dispersers, and dispersers.

[0115] In ink, the ratio of the dispersant content to the pigment content is preferably 0.05 to 1.0 by mass, and more preferably 0.1 to 0.5, from the viewpoint of dispersion stability.

[0116] <Additives> An ink, which is one embodiment of the present disclosure, may optionally contain additives such as co-sensitizers, ultraviolet absorbers, antioxidants, fade inhibitors, conductive salts, solvents, and basic compounds.

[0117] The viscosity of the ink is preferably 0.5 mPa·s to 50 mPa·s, more preferably 5 mPa·s to 40 mPa·s, preferably 7 mPa·s to 35 mPa·s, and even more preferably 8 mPa·s to 30 mPa·s. The viscosity is measured at 25°C using a viscometer, for example, using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0118] The surface tension of the ink is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and even more preferably 25 mN / m to 45 mN / m.

[0119] [Activated energy ray curing inkjet ink] As another embodiment of the present disclosure, preferred embodiments of an active energy ray-curable inkjet ink are shown below. While the above-described active energy ray-curable inkjet ink for beverage containers is for beverage containers, the active energy ray-curable inkjet ink of another embodiment of the present disclosure is not limited to beverage containers. Details of each component contained in the active energy ray-curable inkjet ink of another embodiment of the present disclosure are the same as those for the active energy ray-curable inkjet ink for beverage containers described above, and therefore will not be explained.

[0120] (Aspect 1) It comprises a polymerizable monomer and a polymerizable surfactant, The above polymerizable monomers include monofunctional monomers. An active energy ray-curable inkjet ink in which the above monofunctional monomer content is 60% by mass or more relative to the total amount of the active energy ray-curable inkjet ink.

[0121] (Aspect 2) In embodiment 1, the mass ratio of the monofunctional monomer content to the polymerizable surfactant content is 3 to 100.

[0122] (Aspect 3) In embodiment 1 or embodiment 2, the polymerizable monomer includes a polymerizable monomer having an acid group.

[0123] (Aspect 4) In embodiment 3, the mass ratio of the content of the polymerizable monomer having the acid group to the content of the polymerizable surfactant is 0.2 to 10.

[0124] (Aspect 5) In any of embodiments 1 to 4, the polymerizable surfactant is a silicone-based surfactant having a (meth)acryloyl group.

[0125] (Aspect 6) In any of embodiments 1 to 5, the polymerizable surfactant is a compound that exhibits a surface tension reduction of 5 mN / m or more relative to cyclic trimethylolpropane formal acrylate.

[0126] [Activated energy ray curing ink set (Ink set A)] An ink set A, which is one embodiment of the present disclosure, comprises a first ink containing a polyfunctional monomer and a second ink containing a monofunctional monomer, wherein at least one of the first ink and the second ink contains a polymerizable surfactant. Hereinafter, the first ink and the second ink included in ink set A will also be referred to as first ink A and second ink A, respectively.

[0127] Inkset A, one embodiment of the present disclosure, is an active energy ray curable inkset. That is, the first ink A and the second ink A contained in Inkset A, one embodiment of the present disclosure, are cured by irradiation with active energy rays. The type of active energy ray is not particularly limited and includes, for example, gamma rays, beta rays, electron beams, ultraviolet rays, and visible light. Among these, ultraviolet rays are preferred as the active energy ray. Inkset A, one embodiment of the present disclosure, is preferably an ultraviolet-curable inkset.

[0128] <First Ink A> In one embodiment of the present disclosure, the first ink A in ink set A contains a polyfunctional monomer. Details and preferred embodiments of the polyfunctional monomer are the same as those described above in the activated energy ray curable inkjet ink for beverage containers. The content of the polyfunctional monomer is preferably 25% by mass or more, more preferably 28% by mass or more, and even more preferably 30% by mass or more, based on the total amount of the first ink A.

[0129] The first ink A contains a polymerizable surfactant, and the mass ratio of the polyfunctional monomer content to the polymerizable surfactant content in the first ink A is preferably 4 to 80, more preferably 6 to 80, and even more preferably 15 to 50.

[0130] The first ink A preferably contains a polymerizable monomer with a specific gravity of 1.0 or less.

[0131] A preferred embodiment of the first ink A is the same as the first embodiment of the ink which is one embodiment of the present disclosure, except as described below.

[0132] <Second Ink A> In one embodiment of the present disclosure, the second ink A in ink set A contains a monofunctional monomer. Details and preferred embodiments of the monofunctional monomer are the same as those described above in the activated energy ray curable inkjet ink for beverage containers. The content of the monofunctional monomer is preferably 70% by mass or more, more preferably 71% by mass or more, and even more preferably 72% by mass or more, based on the total amount of the second ink.

[0133] The second ink contains a polymerizable surfactant, and the mass ratio of the monofunctional monomer content to the polymerizable surfactant content in the second ink is preferably 3 to 100, more preferably 4 to 50, and even more preferably 5 to 40.

[0134] The second ink preferably contains a polymerizable monomer having an acidic group.

[0135] A preferred embodiment of the second ink is the same as the second embodiment of the ink which is an embodiment of the present disclosure, except as described below.

[0136] (Polymerizable surfactant) In one embodiment of the present disclosure, ink set A contains a polymerizable surfactant in at least one of the first ink A and the second ink A. Details and preferred embodiments of the polymerizable surfactant are the same as those described above for active energy ray curable inkjet inks for beverage containers. The polymerizable surfactant may be contained in only the first ink A, in only the second ink A, or in both the first and second ink A. From the viewpoint of improving separation, it is preferable that the polymerizable surfactant is contained in both the first and second ink A.

[0137] From the viewpoint of improving separation and suppressing image bleed, it is preferable that at least one of the first ink A and the second ink A contains polymerizable surfactants, namely polymerizable surfactant A with a logP value of 4 or higher and polymerizable surfactant B with a logP value of less than 4. In particular, it is more preferable that the first ink A contains polymerizable surfactant A and polymerizable surfactant B.

[0138] (Coloring agent) In one embodiment of the present disclosure, ink set A, it is preferable that one of the first ink A and the second ink A does not contain a colorant. The second ink, which contains a monofunctional monomer, has excellent adhesion to the substrate and is therefore preferably used as an undercoat. Therefore, it is more preferable that the second ink A does not contain a colorant. Furthermore, when the second ink A is used as an undercoat, it is preferable to record the image with the first ink A. Therefore, it is even more preferable that the first ink A contains a colorant and the second ink A does not contain a colorant.

[0139] If the second ink A does not contain a coloring agent, applying the second ink and then the first ink A to the substrate in that order allows the second ink A to function as a primer.

[0140] -Polyfunctional monomers in ink 1A and ink 2A ​​ / Monofunctional monomers in ink 2A- When the masses of the first ink A and the second ink A are equal, the mass ratio of the total polyfunctional monomer content in the first ink A and the second ink A to the monofunctional monomer content in the second ink A is preferably 0.2 to 0.9, more preferably 0.3 to 0.9, and even more preferably 0.4 to 0.8. When the above mass ratio is 0.2 or higher, alkali peelability and ethanol resistance are improved. On the other hand, when the above mass ratio is 0.9 or lower, adhesion to the substrate is improved.

[0141] -Polymerizable surfactant in Ink 2A ​​ / Polymerizable surfactant in Ink 1A- When the masses of the first ink A and the second ink A are equal, the mass ratio of the polymerizable surfactant content in the second ink A to the polymerizable surfactant content in the first ink A is preferably 0.5 to 12, more preferably 2 to 11, and even more preferably 3 to 10. When the above mass ratio is 0.5 or higher, separation properties and ethanol resistance are improved. On the other hand, when the above mass ratio is 12 or lower, adhesion to the substrate is improved.

[0142] Furthermore, from the viewpoint of further improving adhesion to the substrate, it is preferable that the polymerizable surfactant in the second ink A exhibits a smaller reduction in surface tension relative to CTFA than the polymerizable surfactant in the first ink A. In particular, it is preferable that the polymerizable surfactant in the second ink A exhibits a smaller reduction in surface tension relative to CTFA than the polymerizable surfactant in the first ink A, and that the mass ratio of the polymerizable surfactant content in the second ink A to the polymerizable surfactant content in the first ink A is 2 to 11.

[0143] When the second ink A contains a polymerizable monomer having an acid group, and the first ink A and the second ink A are of equal mass, the mass ratio of the polymerizable surfactant content in the second ink A to the polymerizable surfactant content in the first ink A is preferably 0.5 to 5, more preferably 0.7 to 3, and even more preferably 1.1 to 2. When the above mass ratio is 0.5 or higher, image bleed is suppressed. On the other hand, when the above mass ratio is 5 or lower, separation performance is improved.

[0144] -Polymerizable monomers having acid groups in the second ink A / Monofunctional monomers in the first ink A and the second ink A- When the masses of the first ink A and the second ink A are equal, the mass ratio of the content of polymerizable monomers having acid groups in the second ink A to the total content of monofunctional monomers in the first ink A and the second ink A is preferably 0.01 to 0.15, more preferably 0.04 to 0.11, and even more preferably 0.05 to 0.1. When the above mass ratio is 0.01 or higher, alkali release properties are improved. On the other hand, when the above mass ratio is 0.15 or lower, adhesion properties are improved.

[0145] <Physical properties> The viscosity of the first ink A and the second ink A is preferably 0.5 mPa·s to 50 mPa·s, more preferably 5 mPa·s to 40 mPa·s, even more preferably 7 mPa·s to 35 mPa·s, and particularly preferably 8 mPa·s to 30 mPa·s. The viscosity is measured at 25°C using a viscometer, for example, using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0146] The surface tension of the first ink A is preferably 60 mN / m or less, more preferably 20 mN / m to 30 mN / m, and even more preferably 20 mN / m to 25 mN / m. The surface tension of the second ink A is preferably 60 mN / m or less, more preferably 20 mN / m to 40 mN / m, and even more preferably 23 mN / m to 30 mN / m.

[0147] The surface tension of the second ink A is preferably higher than that of the first ink A.

[0148] As described later, there is no particular order in which the first ink A and the second ink A are applied to the substrate, but from the viewpoint of alkali release properties and adhesion to the substrate, it is preferable to apply the second ink A followed by the first ink A. When the second ink A and the first ink A are applied to the substrate in that order, if the surface tension of the second ink A is higher than that of the first ink A (in other words, if the surface tension of the first ink A is lower than that of the second ink A), the ink droplets of the first ink A spread more easily, improving the image quality.

[0149] Furthermore, if the surface tension of the second ink A is higher than that of the first ink A, the difference between the surface tension of the second ink A and the surface tension of the first ink A is preferably 2 mN / m or more, and more preferably 3 mN / m or more. The upper limit of the above difference is, for example, 10 mN / m.

[0150] [Image recording method] An image recording method, which is one embodiment of the present disclosure, includes the steps of applying the above-mentioned ink (active energy ray curable ink for beverage containers) to the surface of a beverage container using an inkjet recording method, and irradiating the applied ink with active energy rays.

[0151] The material of the beverage container is not particularly limited, and examples include glass and plastic. Among these, the beverage container is preferably a plastic container, and more preferably a PET bottle containing polyethylene terephthalate as the main component.

[0152] The inkjet recording method is not particularly limited as long as it is a method capable of recording an image, and known methods can be used. Examples of inkjet recording methods include a charge control method that ejects ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electrical signal into an acoustic beam, irradiates the ink with it, and ejects the ink using the radiation pressure, and a thermal inkjet (bubble jet®) method that heats the ink to form bubbles and utilizes the resulting pressure.

[0153] Inkjet recording methods include a shuttle method, which uses a short serial head and records while scanning the head in the width direction of the substrate, and a method that uses a short serial head and scans the substrate in the width direction. One example is a line-type system that uses a line head in which recording elements are arranged to cover the entire area of ​​one side.

[0154] In the line method, the substrate can be scanned in a direction intersecting the arrangement direction of the recording elements, allowing for pattern formation across the entire substrate surface. This eliminates the need for a transport system such as a carriage that scans the short head. Furthermore, the line method eliminates the need for complex scanning control of the carriage and the substrate; only the substrate moves, resulting in faster recording speeds compared to the shuttle method.

[0155] The amount of primer composition dispensed from the inkjet head is preferably 1 pL (picoliters) to 100 pL, more preferably 3 pL to 80 pL, and even more preferably 3 pL to 50 pL.

[0156] Examples of active energy rays include gamma rays, beta rays, electron beams, ultraviolet rays, and visible light. Among these, ultraviolet rays are preferred as the active energy ray.

[0157] The peak wavelength of ultraviolet light is preferably, for example, 200 nm to 405 nm, more preferably 250 nm to 400 nm, and even more preferably 300 nm to 400 nm.

[0158] Mercury lamps, gas lasers, and solid-state lasers are the main light sources used for ultraviolet irradiation, with mercury lamps, metal halide lamps, and ultraviolet fluorescent lamps being widely known. UV-LEDs (ultraviolet light-emitting diodes) and UV-LDs (ultraviolet laser diodes) are also promising light sources for ultraviolet irradiation due to their small size, long lifespan, high efficiency, and low cost. Among these, metal halide lamps, high-pressure mercury lamps, medium-pressure mercury lamps, low-pressure mercury lamps, or UV-LEDs are preferred as light sources for ultraviolet irradiation.

[0159] In this disclosure, polymerizing only a portion of the polymerizable monomers in the ink is also referred to as "pre-curing," and irradiation with active energy rays for pre-curing is also referred to as "pinning exposure." In this disclosure, the polymerization of substantially all of the polymerizable monomers in the ink is also referred to as "main curing," and the irradiation of active energy rays for main curing is also referred to as "main exposure."

[0160] In the process of irradiating with active energy rays, it is preferable to pre-cur the ink and then fully cure it. Specifically, it is preferable to apply the ink, perform pinning exposure on the ink, and finally perform full exposure.

[0161] The ink reaction rate after pinning exposure is preferably 10% to 80%.

[0162] Here, the reaction rate of the ink refers to the polymerization rate of the polymerizable monomers contained in the ink, as determined by high-performance liquid chromatography.

[0163] A reaction rate of 10% or higher for the ink suppresses insufficient dot spreading, resulting in improved granularity of the final image.

[0164] Furthermore, by keeping the ink reaction rate below 80%, droplet interference between ink dots is suppressed, resulting in improved image quality in the final product.

[0165] The ink reaction rate is preferably 15% or higher, from the viewpoint of further improving the granularity of the final image.

[0166] From the viewpoint of further improving the image quality of the final image obtained, the ink reaction rate is preferably 75% or less, more preferably 50% or less, preferably 40% or less, more preferably 30% or less, and even more preferably 25% or less.

[0167] The reaction rate of the ink after exposure is preferably between 80% and 100%, more preferably between 85% and 100%, and even more preferably between 90% and 100%. When the reaction rate exceeds 80%, adhesion improves further.

[0168] The ink reaction rate is determined by the following method. A substrate is prepared that has been subjected to the procedure up to the end of irradiation with active energy rays on the ink. A sample piece measuring 20 mm x 50 mm (hereinafter referred to as the post-irradiation sample piece) is cut from the area of ​​the substrate where the ink film is present. The cut post-irradiation sample piece is immersed in 10 mL of THF (tetrahydrofuran) for 24 hours to obtain an eluate from which the ink has been dissolved. The amount of polymerizable monomer (hereinafter referred to as "post-irradiation monomer amount X1") is determined from the obtained eluate by high-performance liquid chromatography. Separately, the same procedure as above is performed, except that the ink on the substrate is not irradiated with active energy rays, to determine the amount of polymerizable monomer (hereinafter referred to as "amount of monomer X1 before irradiation"). Based on the amount of monomer after irradiation X1 and the amount of monomer before irradiation X1, the reaction rate (%) of the ink is calculated using the following formula. Ink reaction rate (%) = ((Amount of monomer before irradiation x 1 - Amount of monomer after irradiation x 1) / Amount of monomer before irradiation x 1) × 100

[0169] The exposure dose of the active energy ray for pinning exposure is 10 mJ / cm², from the viewpoint of more easily achieving the reaction rate of the ink mentioned above. 2~100 mJ / cm 2 Preferably, it is 20 mJ / cm². 2 ~60 mJ / cm² 2 It is preferable that it be so.

[0170] The amount of active energy radiation used for this exposure is 50 mJ / cm², from the viewpoint of completely curing the ink. 2 ~1000 mJ / cm 2 Preferably, it is 200 mJ / cm². 2 ~800 mJ / cm 2 It is preferable that it be so.

[0171] In this exposure procedure, it is preferable to irradiate the substrate with active energy rays in an atmosphere with an oxygen concentration of less than 1 volume%. The oxygen concentration is more preferably 0.5 volume% or less, and even more preferably 0.3 volume% or less.

[0172] In the process of irradiating with active energy rays, from the viewpoint of image quality, it is preferable to irradiate with active energy rays within 0.1 to 5 seconds from the time the ink lands. When performing both pinning exposure and main exposure, it is preferable to irradiate with active energy rays for pinning exposure within 0.1 to 5 seconds from the time the ink lands. It is more preferable that the time from the time the ink lands until the irradiation of active energy rays (or, in the case of performing both pinning exposure and main exposure, the active energy rays for pinning exposure) is within 0.2 to 1 second.

[0173] [Image recording method] An image recording method according to one embodiment of the present disclosure uses the above-mentioned ink set A (active energy ray curable ink set) and includes the steps of applying a first ink and a second ink A onto a substrate using an inkjet recording method, and irradiating with active energy rays after the first ink and the second ink A have been applied, respectively.

[0174] (A process of applying the first ink A and the second ink A onto a substrate using an inkjet recording method.) The order in which the first ink A and the second ink A are applied to the substrate is not particularly limited, but from the viewpoint of alkali-removable properties and adhesion to the substrate, it is preferable to apply the second ink A followed by the first ink A. Since the second ink A contains a monofunctional monomer, it has excellent adhesion to the substrate. On the other hand, since the first ink A contains a polyfunctional monomer, it has excellent alkali-removable properties. By making the second ink A the ink applied directly to the substrate, adhesion to the substrate can be ensured. Furthermore, when the image recording material is immersed in an alkaline solution, the outermost surface of the ink film comes into contact with the alkali, so by applying the first ink after the second ink, alkali-removable properties can be ensured.

[0175] The type of substrate is not particularly limited, and any commonly known substrate can be used. Examples of substrates include glass, quartz, and plastic films. Examples of resins constituting the plastic film include cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, acrylic resin, chlorinated polyolefin resin, polyethersulfone resin, polyethylene terephthalate (PET), polyethylene naphthalate, nylon, polyethylene, polystyrene, polypropylene, polycycloolefin resin, polyimide resin, polycarbonate resin, and polyvinyl acetal. The plastic film may contain only one of these resins, or it may be a film containing a mixture of two or more of these resins.

[0176] The thickness of the substrate is not particularly limited, for example, 1 μm to 10 mm. When the substrate is a film, the thickness is preferably 1 μm to 500 μm, more preferably 2 μm to 200 μm, even more preferably 5 μm to 100 μm, and particularly preferably 10 μm to 90 μm. When the substrate is glass, the thickness is preferably 0.1 mm to 10 mm, more preferably 0.15 mm to 8 mm, and even more preferably 0.2 mm to 5 mm.

[0177] Furthermore, the base material may be a beverage container, and preferred embodiments of the beverage container are as described above.

[0178] Details of the inkjet recording method are as described above.

[0179] (A process in which active energy rays are irradiated after the first ink A and the second ink A are applied, respectively.)

[0180] Examples of active energy rays include gamma rays, beta rays, electron beams, ultraviolet rays, and visible light. Among these, ultraviolet rays are preferred as the active energy ray.

[0181] The peak wavelength of ultraviolet light is preferably, for example, 200 nm to 405 nm, more preferably 250 nm to 400 nm, and even more preferably 300 nm to 400 nm.

[0182] Mercury lamps, gas lasers, and solid-state lasers are the main light sources used for ultraviolet irradiation, with mercury lamps, metal halide lamps, and ultraviolet fluorescent lamps being widely known. UV-LEDs (ultraviolet light-emitting diodes) and UV-LDs (ultraviolet laser diodes) are also promising light sources for ultraviolet irradiation due to their small size, long lifespan, high efficiency, and low cost. Among these, metal halide lamps, high-pressure mercury lamps, medium-pressure mercury lamps, low-pressure mercury lamps, or UV-LEDs are preferred as light sources for ultraviolet irradiation.

[0183] In the following explanations common to both Ink 1A and Ink 2A, the term "ink" will also be used. In the step of irradiating with active energy rays, it is preferable to pre-cure the first ink A and the second ink A before performing full curing. Specifically, it is preferable to apply the second ink A, then perform pinning exposure on the second ink A, apply the first ink A onto the pre-cured second ink A, apply the first ink A again, perform pinning exposure on the first ink A, and finally perform full exposure.

[0184] The ink reaction rate after pinning exposure is preferably 10% to 80%.

[0185] By having a reaction rate of 10% or more for the ink (e.g., second ink A), insufficient dot spreading of the ink (e.g., first ink) applied on this ink is suppressed, and as a result, the granularity of the final image is improved.

[0186] Furthermore, by keeping the reaction rate of the ink (e.g., second ink A) below 80%, excessive spreading of the ink (e.g., first ink A) applied to this ink is suppressed, and droplet interference between ink dots is also suppressed, resulting in improved image quality in the final product.

[0187] The ink reaction rate is preferably 15% or higher, from the viewpoint of further improving the granularity of the final image.

[0188] From the viewpoint of further improving the image quality of the final image obtained, the ink reaction rate is preferably 75% or less, more preferably 50% or less, preferably 40% or less, more preferably 30% or less, and even more preferably 25% or less.

[0189] The reaction rate of the ink after exposure is preferably between 80% and 100%, more preferably between 85% and 100%, and even more preferably between 90% and 100%. When the reaction rate exceeds 80%, adhesion improves further.

[0190] The exposure dose of the active energy ray for pinning exposure is 10 mJ / cm², from the viewpoint of more easily achieving the reaction rate of the ink mentioned above. 2 ~100 mJ / cm 2 Preferably, it is 20 mJ / cm². 2 ~60 mJ / cm² 2 It is preferable that it be so.

[0191] The exposure dose of the active energy ray for this exposure is 50 mJ / cm², from the viewpoint of completely curing the first ink A and the second ink A. 2 ~1000 mJ / cm 2 Preferably, it is 200 mJ / cm². 2 ~800 mJ / cm 2 It is preferable that it be so.

[0192] In this exposure procedure, it is preferable to irradiate the substrate with active energy rays in an atmosphere with an oxygen concentration of less than 1 volume%. The oxygen concentration is more preferably 0.5 volume% or less, and even more preferably 0.3 volume% or less.

[0193] Furthermore, in the process of irradiating with active energy rays, from the viewpoint of image quality, it is preferable to irradiate with active energy rays within 0.2 to 5 seconds from the time when the first ink A and the second ink A each land. When performing both pinning exposure and main exposure, it is preferable to irradiate with active energy rays for pinning exposure within 0.2 to 5 seconds from the time when the first ink A and the second ink A each land. It is more preferable that the time from the time when the first ink A and the second ink A each land until the irradiation of active energy rays (or, in the case of performing both pinning exposure and main exposure, active energy rays for pinning exposure) is within 0.3 to 2 seconds.

[0194] [Activated energy ray curing ink set (Ink set B)] An embodiment of the present disclosure, ink set B, comprises a first ink containing a colorant and a polymerizable monomer having a hydroxyl group, and a second ink containing a polymerizable monomer having an acid group. Hereinafter, the first ink and the second ink included in ink set B will also be referred to as first ink B and second ink B, respectively.

[0195] Inkset B, one embodiment of the present disclosure, is an active energy ray curable inkset. That is, the first ink B and the second ink B contained in Inkset B, one embodiment of the present disclosure, are cured by irradiation with active energy rays. The type of active energy ray is not particularly limited and includes, for example, gamma rays, beta rays, electron beams, ultraviolet rays, and visible light. Among these, ultraviolet rays are preferred as the active energy ray. Inkset B, one embodiment of the present disclosure, is preferably an ultraviolet-curable inkset.

[0196] <First Ink B> In one embodiment of the present disclosure, the first ink B in ink set B comprises a colorant and a polymerizable monomer having a hydroxyl group.

[0197] If the first ink B contains a polymerizable monomer with a hydroxyl group, the alkaline aqueous solution easily penetrates the ink film. Therefore, when an image recording is immersed in an alkaline aqueous solution, the ink film is likely to peel off from the substrate.

[0198] The number of hydroxyl groups in a polymerizable monomer containing hydroxyl groups is not particularly limited, and is, for example, 1 to 6. From the viewpoint of ink viscosity, the number of hydroxyl groups is preferably 1 to 3, and more preferably 1 or 2.

[0199] Examples of polymerizable monomers having a hydroxyl group include (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; Vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, and hydroxybutyl vinyl ether; and Examples of allyl ethers include hydroxyethyl allyl ether, hydroxypropyl allyl ether, and hydroxybutyl allyl ether.

[0200] In particular, from the viewpoint of reactivity, the polymerizable monomer having a hydroxyl group is preferably a (meth)acrylate having a hydroxyl group.

[0201] From the viewpoint of further improving alkali peelability and water resistance, the content of polymerizable monomers having hydroxyl groups is preferably 20% to 75% by mass, more preferably 30% to 70% by mass, and even more preferably 40% to 60% by mass, relative to the total amount of the first ink B.

[0202] The first ink B contains at least one coloring agent. Specific examples and preferred embodiments of the colorant contained in the first ink B can be found by referring to the colorants in the activated energy ray curable inkjet inks for beverage containers described above.

[0203] The first ink B may contain polymerizable monomers other than polymerizable monomers having hydroxyl groups. Specific examples and preferred embodiments of these other polymerizable monomers can be found in the polymerizable monomers other than those having hydroxyl groups in the activated energy ray curable inkjet inks for beverage containers described above.

[0204] The first ink B preferably contains at least one dispersant. The first ink B preferably contains at least one polymerization initiator. The first ink B preferably contains at least one polymerization inhibitor. Specific examples and preferred embodiments of dispersants, polymerization initiators, and polymerization inhibitors can be found in the dispersants, polymerization initiators, and polymerization inhibitors used in the previously described active energy ray-curable inkjet inks for beverage containers.

[0205] The first ink B preferably contains at least one surfactant. The type of surfactant that may be included in the first ink B is not particularly limited and may be anionic surfactant, cationic surfactant, or nonionic surfactant. Furthermore, the surfactant may be a silicone-based surfactant or a fluorine-based surfactant.

[0206] Furthermore, the surfactant may be a polymerizable surfactant or a non-polymerizable surfactant. Specific examples and preferred embodiments of polymerizable surfactants can be found in the polymerizable surfactants used in the previously described active energy ray curable inkjet inks for beverage containers.

[0207] The first ink B may optionally contain additives such as co-sensitizers, ultraviolet absorbers, antioxidants, fade inhibitors, conductive salts, solvents, and basic compounds.

[0208] <Second Ink B> In one embodiment of the present disclosure, the second ink B in ink set B contains a polymerizable monomer having an acidic group.

[0209] For details of the acid group, and for specific examples and preferred embodiments of polymerizable monomers having an acid group, refer to the polymerizable monomers having an acid group in the activated energy ray curable inkjet ink for beverage containers described above. The polymerizable monomer having an acid group is preferably a polymerizable monomer having a carboxyl group.

[0210] Acidic groups react with alkalis to form salts, which improves their water solubility. Therefore, if the second ink B contains polymerizable monomers with acidic groups, its alkali-removable properties improve.

[0211] Furthermore, since the first ink B contains a polymerizable monomer having a hydroxyl group, and the second ink B contains a polymerizable monomer having an acid group, both the first ink film formed by the first ink B and the second ink film formed by the second ink B are hydrophilic. When an image recording is immersed in water, both the first and second ink films expand due to the water, thus suppressing curing shrinkage. Therefore, the image is less likely to peel off the substrate due to water, and it has excellent water resistance.

[0212] From the viewpoint of improving alkali-peelability and water resistance, the content of polymerizable monomers having acidic groups is preferably 5% to 25% by mass, and more preferably 10% to 20% by mass, relative to the total amount of the second ink B. When the content of polymerizable monomers having acidic groups is 5% by mass or more, the effects of alkali-peelability and water resistance based on the acidic groups are more pronounced. On the other hand, when the content of polymerizable monomers having acidic groups is 25% by mass or less, the viscosity of the ink is appropriately maintained, resulting in excellent ejection performance when ejected using an inkjet recording method. As the second ink is applied more uniformly, an image with excellent alkali-peelability and water resistance can be obtained.

[0213] The second ink B preferably further contains a polymerizable monomer having a hydroxyl group. When the second ink B contains a polymerizable monomer having a hydroxyl group, the hydrophilicity of the second ink B is improved, and its alkali-removable properties are further enhanced.

[0214] Specific examples and preferred embodiments of polymerizable monomers having hydroxyl groups can be found in the polymerizable monomers having hydroxyl groups in the first ink B of the ink set B described above.

[0215] -Total content of polymerizable monomers having acid groups and polymerizable monomers having hydroxyl groups- In the second ink B, the total content of polymerizable monomers having acidic groups and polymerizable monomers having hydroxyl groups is preferably 10% to 50% by mass, and more preferably 20% to 45% by mass, relative to the total amount of the second ink B. When the total content is 10% by mass or more, the alkali peelability is excellent. On the other hand, when the total content is 50% by mass or less, the water resistance is excellent.

[0216] -Content of polymerizable monomers having hydroxyl groups in the first ink B / Total content of polymerizable monomers having acid groups and polymerizable monomers having hydroxyl groups in the second ink B- When the masses of the first ink B and the second ink B are equal, the mass ratio of the content of polymerizable monomers having acidic groups in the first ink B to the total content of polymerizable monomers having acidic groups and polymerizable monomers having hydroxyl groups in the second ink B is preferably 1 to 4, and more preferably 1 to 3. If the above mass ratio is 1 or more, the water resistance is superior. On the other hand, if the above mass ratio is 4 or less, the alkali peelability is superior.

[0217] The second ink B preferably contains at least one dispersant. The second ink B preferably contains at least one polymerization initiator. The second ink B preferably contains at least one polymerization inhibitor. Specific examples and preferred embodiments of dispersants, polymerization initiators, and polymerization inhibitors can be found in the dispersants, polymerization initiators, and polymerization inhibitors used in the previously described active energy ray-curable inkjet inks for beverage containers.

[0218] The second ink B preferably contains at least one surfactant. The type of surfactant that may be included in the second ink B is not particularly limited and may be anionic surfactant, cationic surfactant, or nonionic surfactant. Furthermore, the surfactant may be a silicone-based surfactant or a fluorine-based surfactant.

[0219] Further, the surfactant may be a polymerizable surfactant or a non-polymerizable surfactant. As specific examples and preferred embodiments of the polymerizable surfactant, reference can be made to the polymerizable surfactants in the above-described active energy ray-curable inkjet ink for beverage containers.

[0220] The second ink B may contain additives such as a co-sensitizer, an ultraviolet absorber, an antioxidant, a fading inhibitor, a conductive salt, a solvent, and a basic compound, if necessary.

[0221] The second ink B preferably does not contain a colorant and is preferably used as an undercoat liquid.

[0222] An image recording method according to an embodiment of the present disclosure uses the above ink set B (active energy ray-curable ink set), and includes a step of applying the first ink B and the second ink B onto a substrate using an inkjet recording method, and a step of irradiating active energy rays after the first ink B and the second ink B are each applied.

[0223] Details of the image recording method using the ink set B are the same as those of the image recording method using the ink set A.

Examples

[0224] Hereinafter, the present disclosure will be described more specifically with reference to examples. However, the present disclosure is not limited to the following examples as long as the gist thereof is not exceeded.

[0225] <Examples #1 to #17, Examples #33 to #42, Comparative Examples #1 to #4> [Preparation of Ink] First, a black pigment dispersion was prepared.

[0226] 25 parts by mass of a black pigment (product name: "Special Black 250", manufactured by Orion Engineered Carbons), 5 parts by mass of a dispersant (product name: "SOLSPERSE 32000", manufactured by Lubrizol), and 75 parts by mass of cyclic trimethylolpropane formal acrylate (product name: "Biscoat #200", manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a dispersion medium were put into a dispersing machine motor mill M50 (manufactured by Aiger), and zirconia beads with a diameter of 0.65 mm were used to perform a dispersion treatment at a peripheral speed of 9 m / s for 4 hours to obtain a black pigment dispersion liquid.

[0227] Next, the prepared black pigment dispersion liquid, the polymerizable monomers (monofunctional monomers and polyfunctional monomers), polymerization initiator, polymerization inhibitor, and surfactant described in Tables 1 to 2, Table 4, and Table 7 below were mixed so that the content of each component was the content (% by mass) described in Tables 1 to 2, Table 4, and Table 7. The mixture was stirred for 20 minutes at 25°C and 5000 revolutions per minute using a mixer (product name: "L4R", manufactured by Silverstone) to obtain an ink.

[0228] <Examples 18 to 32, Comparative Examples 5 to 8> [Preparation of Ink] The polymerizable monomers (monofunctional monomers and polyfunctional monomers), polymerization initiator, polymerization inhibitor, and surfactant described in Tables 3 to 4 below were mixed so that the content of each component was the content (% by mass) described in Tables 3 to 4. The mixture was stirred for 20 minutes at 25°C and 5000 revolutions per minute using a mixer (product name: "L4R", manufactured by Silverstone) to obtain an ink.

[0229] <Examples 101 to 118, Examples 201 to 227, Comparative Example 101> [Preparation of First Ink] A black pigment dispersion liquid was prepared in the same manner as in Example 1. Thereafter, the polymerizable monomers (monofunctional monomers and polyfunctional monomers), polymerization initiator, polymerization inhibitor, and surfactant described in Tables 5 to 6 and Tables 8 to 10 below were mixed so that the content of each component was the content (% by mass) described in Tables 5 to 6 and Tables 8 to 10, and the first ink was prepared in the same manner as in Example 1.

[0230] [Preparation of the second ink] The polymerizable monomers (monofunctional monomers and polyfunctional monomers), polymerization initiators, polymerization inhibitors, and surfactants listed in Tables 5 to 6 and Tables 8 to 10 below were mixed so that the content of each component was as indicated in Tables 5 to 6 and Tables 8 to 10 (mass%), and the second ink was prepared in the same manner as in Example 18.

[0231] Details of each component listed in Tables 1 to 10 are as follows:

[0232] <Polymerizable monomers> -Polyfunctional monomer- • 3MPDDA: 3-methyl-1,5-pentanediol diacrylate (product name "SR341", manufactured by Sartomer) • TEGDA: Triethylene glycol diacrylate (product name "3EG-A", manufactured by Kyoeisha Chemical Co., Ltd.) • DDDA: 1,10-decanediol diacrylate (product name "SR595", manufactured by Sartomer) -Monofunctional monomers- • CTFA: Cyclic trimethylolpropane formal acrylate (product name "Viscoat #200", manufactured by Osaka Organic Chemical Industry Co., Ltd.) • A-SA: 2-Acryloyloxyethyl succinate (product name "NK Ester A-SA", manufactured by Shin Nakamura Chemical Industry Co., Ltd.) • STA: Stearyl acrylate (product name "STA", manufactured by Osaka Organic Chemical Industry Co., Ltd.) • 4-HBA: 4-hydroxybutyl acrylate (product name "4-HBA", manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0233] <Polymerization initiator> • Omnirad 819: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (manufactured by IGM Resins BV) Speedcure7010: 1,3-di({α-[1-chloro-9-oxo-9H-thioxanthene-4-yl)oxy]acetylpoly[oxy(1-methylethylene)]}oxy)-2,2-bis({α-[1-methylethylene)]}oxymethyl)propane

[0234] <Polymerization inhibitors> • Q-1301: N-nitroso-N-phenylhydroxylamine aluminum salt (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0235] <Coloring agent> • Black pigment: Special Black 250 (manufactured by Orion Engineered Carbons)

[0236] <Dispersant> • SOLSPERSE32000: Polyethyleneimine-based dispersant (manufactured by Lubrizol)

[0237] <Surfactants> • Acrylic surfactant containing (meth)acryloyl group: Product name "CN821" (manufactured by Sartomer) • (Meth)acryloyl group-containing fluorinated surfactant: Product name "Megafac RS-76-NS" (manufactured by DIC Corporation) • (Meth)acryloyl group-containing silicone-based surfactant 1: Product name "Tegorad2100" (manufactured by Evonik) • (Meth)acryloyl group-containing silicone-based surfactant 2: Product name "Tegorad2010" (manufactured by Evonik) • (Meth)acryloyl group-containing silicone-based surfactant 3: Product name "Tegorad2500" (manufactured by Evonik) • (Meth)acryloyl group-containing silicone-based surfactant 4: Product name "Tegorad2650" (manufactured by Evonik) • Non-polymerizable acrylic surfactant: Product name "BYK361N" (manufactured by BYK) • Non-polymerizable fluorinated surfactant: Product name "Megafac F555" (manufactured by DIC Corporation) • Non-polymerizable silicone-based surfactant: Product name "BYK-UV3510" (manufactured by BYK) Regarding products in which the surfactant content is not 100% by mass (for example, products containing a solvent in addition to the surfactant), they were prepared so that the surfactant content would be 100% by mass, and the surfactant alone was used.

[0238] [Image recording] <Examples 1 to 42, Comparative Examples 1 to 8> Using an inkjet recording apparatus (product name "CylinderJET", manufactured by Tri-Tech Co., Ltd.) and an inkjet head (product name "KJ4A-RH", manufactured by Kyocera), the prepared ink was applied onto the body of a PET bottle (product name "PET500 round", manufactured by Kokugo Co., Ltd.). Specifically, on a surface with dimensions of 7 cm in the longitudinal direction of the PET bottle and 5 cm in the circumferential direction of the PET bottle, ink was applied under the conditions of a droplet discharge amount of 11 pL (picoliters) and a resolution of 600×600 dpi (dots per inch), and a 100% solid image with a thickness of 4 μm was recorded. After applying the ink, using the LED light source attached to the inkjet recording apparatus, ultraviolet rays were irradiated with an exposure amount of 40 mJ / cm Then, ultraviolet rays were irradiated with an exposure amount of 40 mJ / cm². As the LED light source, a UV-LED irradiator (product name "G4B", manufactured by Kyocera) with a peak wavelength of 385 nm was used. Then, the PET bottle on which the image was recorded was placed in the exposure machine. The above PET bottle was set horizontally. The exposure machine can rotate the above PET bottle. While rotating the entire image recorded on the PET bottle, it was exposed using the LED light source. The exposure machine and a nitrogen gas generator with a compressor (product name "Maxi-Flow30", manufactured by Inhouse Gas) were connected at a pressure of 0.2 MPa·s, and nitrogen was flowed so that the oxygen concentration in the exposure machine would be 1% by volume or less. Using the LED light source, ultraviolet rays were irradiated with an exposure amount of 500 mJ / cm² 2 to completely cure the ink and obtain an image recording. 2 to completely cure the ink and obtain an image recording.

[0239] <Examples 101 to 118, Examples 201 to 227> Using an inkjet recording device (product name "CylinderJET", manufactured by Tritech) and an inkjet head (product name "KJ4A-RH", manufactured by Kyocera), the prepared second ink was applied to the body of a PET bottle (product name "PET500 Maru", manufactured by Kokugo). Specifically, the second ink was applied to a surface measuring 7 cm in the longitudinal direction and 5 cm in the circumferential direction of the PET bottle, under conditions of a droplet volume of 11 pL (picoliters) and a resolution of 600 × 600 dpi (dots per inch), recording a 100% solid image with a thickness of 4 μm. Furthermore, under the same conditions as the application of the second ink, the first ink was applied on top of the second ink, recording a 100% solid image with a thickness of 4 μm. After the application of the second ink and after the application of the first ink, an exposure dose of 40 mJ / cm² was used using the LED light source attached to the inkjet recording device. 2 Ultraviolet light was irradiated. A UV-LED irradiator with a peak wavelength of 385 nm (product name "G4B", manufactured by Kyocera Corporation) was used as the LED light source. Then, the PET bottle on which the image was recorded was placed inside the exposure machine. The PET bottle was set horizontally. The exposure machine can rotate the PET bottle. While rotating the entire image recorded on the PET bottle, exposure was performed using the LED light source. The exposure machine and a nitrogen gas generator with a compressor (product name "Maxi-Flow30", manufactured by Inhouse Gas Corporation) were connected at a pressure of 0.2 MPa·s, and nitrogen was flowed so that the oxygen concentration inside the exposure machine was 1 volume% or less. An exposure dose of 500 mJ / cm² was used with the LED light source. 2 The first and second inks were completely cured by irradiating them with ultraviolet light to obtain an image recording. "Complete curing" refers to the process of curing plain paper (for example, Fuji Xerox copy paper C2, product code "V436") under a uniform force (500 mN / cm²). 2 ~1,000 mN / cm 2 The hardening process can be determined by pressing the image with a certain value (within a specified range) and seeing if the image transfers to the paper. In other words, if no transfer occurs at all, it is considered fully hardened.

[0240] [evaluation] For each example and comparative example, the obtained image recordings were used to evaluate separation properties, alkali peelability, adhesion, and ethanol resistance. For Examples 33 to 42 and Examples 201 to 227, further evaluation of repulsion suppression was performed. The evaluation methods are as follows.

[0241] <Separability 1> For the evaluation, the mass of the PET bottle was measured before image recording. The mass of the PET bottle after image recording (the image recording object) was also measured. The mass of the ink film formed on the surface of the PET bottle (initial mass of the ink film) was calculated based on the following formula. Initial mass of the ink film = (Mass of the image recording object) - (Mass of the PET bottle before image recording) Next, the image recording was immersed in a 1.5% by mass sodium hydroxide aqueous solution at 85°C for 15 minutes. After 5 minutes, the ink film floating at the solution interface was collected. The collected ink film was dried, and its mass after drying was measured. The recovery rate was calculated based on the following formula. Recovery rate (mass %) = (mass of recovered ink film after drying / initial mass of ink film) × 100 The separation performance (level 1) was evaluated based on the recovery rate. A higher recovery rate indicates better separation performance. The evaluation criteria are as follows: 5. The recovery rate was 90% by mass or higher. 4. The recovery rate was between 70% and 90% by mass. 3: The recovery rate was between 50% by mass and less than 70% by mass. 2: The recovery rate was between 20% by mass and less than 50% by mass. 1: The recovery rate was less than 20% by mass.

[0242] <Separability 2> The recovery rate was calculated using the same method as for evaluating separation performance 1, except that the image recordings were immersed in a 1.5% by mass sodium hydroxide aqueous solution at 85°C for 10 minutes. Based on the recovery rate, the separability 2 was evaluated. Furthermore, the evaluation method for separation performance 2 is considered less effective than the evaluation method for separation performance 1 because the immersion time of the image recording is shorter. 7. The recovery rate was 90% by mass or higher. 6. The recovery rate was between 80% and 90% by mass. 5. The recovery rate was between 70% and 80% by mass. 4. The recovery rate was between 60% and 70% by mass. 3: The recovery rate was between 50% by mass and less than 60% by mass. 2: The recovery rate was between 40% by mass and less than 50% by mass. 1: The recovery rate was less than 40% by mass.

[0243] <Alkaline peeling properties> The obtained image recordings were immersed in a 1.5% by mass sodium hydroxide aqueous solution at 85°C, and the peeling state was observed visually. The peeling time was defined as the time from when the image recording was immersed until the ink film completely peeled off from the image recording. The alkali-stripping properties were evaluated based on the peeling time. A shorter peeling time indicates superior alkali-stripping performance. The evaluation criteria are as follows: 5. The peeling time was less than 5 minutes. 4. The peeling time was between 5 and 10 minutes. 3. The peeling time was between 10 and 15 minutes. 2: The peeling time was between 15 and 30 minutes. 1: The peeling time was more than 30 minutes.

[0244] <Adhesion> Except for not performing cross-cutting on the obtained image recordings, the tape adhesion test was conducted in accordance with the description in JIS K5600-5-6:1999. After the test, the image recordings were visually inspected. The percentage of the area where the ink film peeled off (peeling area ratio) (%) was calculated relative to the entire evaluation area. Adhesion was evaluated based on the peeling area ratio. A smaller peeling area ratio indicates better adhesion. The evaluation criteria are as follows: 5: No peeling of the ink film occurred. 4: The peeling area ratio was greater than 0% and less than or equal to 10%. 3: The peeling area ratio was between 10% and 20%. 2: The peeling area ratio was between 20% and 50%. 1: The peeling area ratio was over 50%.

[0245] <Ethanol resistance> The surface of the obtained image recording was rubbed with a cotton swab soaked in a 75% by mass ethanol solution. After each rub, the rubbed surface was visually inspected to check for any peeling of the ink film. If no peeling of the ink film was observed, the rubbing was continued with the cotton swab up to 20 times. On the other hand, if peeling of the ink film was observed, the rubbing was stopped at that point. Ethanol resistance was evaluated based on the number of times it was rubbed. A higher number of rubs indicates better ethanol resistance. The evaluation criteria are as follows: Even after rubbing it 5:20 times, no peeling of the ink film was observed. 4. The number of rubs before the peeling of the ink film was observed was 15-20. 3. The number of rubs before the peeling of the ink film was observed was between 10 and 14. 2: The number of rubs before the peeling of the ink film was observed was between 5 and 9. 1: The number of times the ink film was rubbed before peeling was observed was between 1 and 4.

[0246] <Rejection suppression> The surface on which the image was recorded in the obtained image recording was visually observed, and the suppression of repulsion was evaluated based on the number of repulsion marks with a diameter of 100 μm or more in a 1 cm × 1 cm area. The fewer the repulsion marks, the better the suppression of repulsion is considered to be. The evaluation criteria are as follows. 5: There were 0 bullet marks. 4: There were 1 to 3 bullet marks. 3: There were 4-5 bullet marks. 2: There were 6 to 10 bullet marks. 1: There were 11 or more bullet holes.

[0247] The evaluation results are shown in Tables 1 to 10.

[0248] In Tables 1 to 10, "polyfunctional monomer / polymerizable surfactant" refers to the mass ratio of the polyfunctional monomer content to the polymerizable surfactant content. "Monofunctional monomer / polymerizable surfactant" refers to the mass ratio of the monofunctional monomer content to the polymerizable surfactant content. "Acid group-containing monomer / polymerizable surfactant" refers to the mass ratio of the monomer containing an acid group to the polymerizable surfactant content. Furthermore, for surfactants, the degree of surface tension reduction relative to CTFA is indicated. The degree of surface tension reduction relative to CTFA was calculated based on the following formula. The degree of reduction in surface tension relative to CTFA = (Surface tension of CTFA) - (Surface tension when surfactant is added at an amount of 0.5% by mass relative to CTFA)

[0249] In Tables 5 to 10, "Polyfunctional monomers in the first and second inks / Monofunctional monomers in the second ink" refers to the mass ratio of the total content of polyfunctional monomers in the first and second inks to the content of monofunctional monomers in the second ink. "Polymerizable surfactants in the first and second inks / Monofunctional monomers in the second ink" refers to the mass ratio of the total content of polymerizable surfactants in the first and second inks to the content of monofunctional monomers in the second ink. "Polymerizable monomers with acidic groups in the second ink / Monofunctional monomers in the first and second inks" refers to the mass ratio of the content of polymerizable monomers with acidic groups in the second ink to the total content of monofunctional monomers in the first and second inks.

[0250] In Tables 7, 9, and 10, "polymerizable monomers with a specific gravity greater than 1.0 / polymerizable monomers with a specific gravity of 1.0 or less" refers to the mass ratio of polymerizable monomers with a specific gravity greater than 1.0 to the content of polymerizable monomers with a specific gravity of 1.0 or less.

[0251] In Tables 7 and 10, "Polymerizable surfactant B / Polymerizable surfactant A" refers to the mass ratio of polymerizable surfactant B to polymerizable surfactant A. Polymerizable surfactant A is a polymerizable surfactant with a logP value of 4.0 or higher, and polymerizable surfactant B is a polymerizable surfactant with a logP value of less than 4.0. The logP values ​​of polymerizable surfactants were measured according to the method specified in JIS Z 7260-117:2006.

[0252] [Table 1]

[0253] [Table 2]

[0254] [Table 3]

[0255] [Table 4]

[0256] [Table 5]

[0257] [Table 6]

[0258] [Table 7]

[0259] [Table 8]

[0260] [Table 9]

[0261] [Table 10]

[0262] As shown in Tables 1 to 4, Examples 1 to 32 contained polymerizable monomers and polymerizable surfactants, resulting in excellent image separation. Furthermore, as shown in Tables 5 and 6, Examples 101 to 118 comprised a first ink containing a polyfunctional monomer and a second ink containing a monofunctional monomer, and at least one of the first and second inks contained a polymerizable surfactant, resulting in excellent image separation.

[0263] On the other hand, Comparative Examples 1 to 4 and Comparative Examples 5 to 8 were found to have inferior image separation performance because they did not contain polymerizable surfactants.

[0264] Example 15, having a polyfunctional monomer content of 25% by mass or more relative to the total amount of ink, was found to have superior alkali-removable properties and ethanol resistance compared to Example 16. On the other hand, Example 31, having a monofunctional monomer content of 60% by mass or more relative to the total amount of ink, was found to have superior adhesion compared to Example 32.

[0265] Example 15 showed superior alkali-stripping properties and ethanol resistance compared to Example 16 because the mass ratio of polyfunctional monomer content to polymerizable surfactant content was 6 or higher. Furthermore, Example 9 showed superior separation properties compared to Example 10 because the mass ratio of polyfunctional monomer content to polymerizable surfactant content was 80 or less.

[0266] Example 19 showed superior adhesion compared to Example 18 because the mass ratio of monofunctional monomer content to polymerizable surfactant content was 5 or higher. Furthermore, Example 22 showed superior separation properties and ethanol resistance compared to Example 23 because the mass ratio of monofunctional monomer content to polymerizable surfactant content was 100 or less.

[0267] Example 25 was found to have superior alkali-removal properties compared to Example 18, because it contains polymerizable monomers that have an acidic group.

[0268] In Example 27, the mass ratio of polymerizable monomers with acidic groups to polymerizable surfactant content was 0.2 or higher, resulting in superior alkali-removal properties compared to Example 26. Furthermore, in Example 29, the mass ratio of polymerizable monomers with acidic groups to polymerizable surfactant content was 10 or less, resulting in superior ethanol resistance compared to Example 30.

[0269] In Example 3, the polymerizable surfactant is a silicone-based surfactant having a (meth)acryloyl group, and it was found to have superior ethanol resistance compared to Examples 1 and 2.

[0270] Examples 2 and 3 showed superior separation compared to Example 1 because the polymerizable surfactant was a compound with a surface tension reduction of 5 mN / m or more relative to CTFA.

[0271] In Example 112, both the first and second inks contained polymerizable surfactants, and it was found that they exhibited superior separation properties and ethanol resistance compared to Example 116.

[0272] In Example 104, the mass ratio of the total polyfunctional monomer content in the first and second inks to the monofunctional monomer content in the second ink was 0.2 or higher, resulting in superior alkali peelability and ethanol resistance compared to Example 105. Furthermore, in Example 102, the mass ratio of the total polyfunctional monomer content in the first and second inks to the monofunctional monomer content in the second ink was 0.9 or lower, resulting in superior adhesion compared to Example 101.

[0273] In Example 106, the mass ratio of the polymerizable surfactant content in the second ink to the polymerizable surfactant content in the first ink was 2 or more, resulting in superior separation properties and ethanol resistance compared to Example 107. Furthermore, in Example 108, the mass ratio of the polymerizable surfactant content in the second ink to the polymerizable surfactant content in the first ink was 11 or less, resulting in superior adhesion compared to Example 109.

[0274] In Example 113, the mass ratio of the content of polymerizable monomers having acid groups in the second ink to the total content of monofunctional monomers in the first and second inks was 0.05 or higher, and it was found that it had superior alkali-removable properties compared to Example 112. In Example 114, the total content of monofunctional monomers in the first and second inks was In contrast, the mass ratio of polymerizable monomers containing acidic groups in the second ink was 0.1 or less, resulting in superior adhesion compared to Example 115.

[0275] As shown in Table 7, in Examples 33 to 36, the ink contained polymerizable surfactant A and polymerizable surfactant B, and it was found to have superior separation properties compared to Example 8.

[0276] As shown in Table 7, in Examples 37 to 41, the ink contained polymerizable monomers with a specific gravity of 1.0 or less, and it was found to have superior separation properties compared to Example 8.

[0277] As shown in Table 9, in Examples 212 to 216, the first ink contained polymerizable monomers with a specific gravity of 1.0 or less, and it was found to have superior separation properties compared to Example 201.

[0278] In Examples 217 to 220, the first ink contained polymerizable surfactant A and polymerizable surfactant B, and it was found to have superior separation properties compared to Example 201.

[0279] <Examples 119 to 123> In Examples 119 to 123, the first and second inks were prepared in the same manner as in Example 113, except that the black pigment in the first ink was changed to the following. Specifically, in Example 119, the black pigment in the first ink was changed to a cyan pigment (product name "Heliogen® Blue D 7110 F", manufactured by BASF). In Example 120, the black pigment in the first ink was changed to a magenta pigment (product name "CINQUASIA MAGENTA RT-355D", manufactured by BASF). In Example 121, the black pigment in the first ink was changed to a yellow pigment (product name "NOVOPERM YELLOW H2G", manufactured by Clariant). In Example 118, the black pigment in the first ink was replaced with a white pigment (product name "KRONOS 2300", manufactured by KRONOS). The white pigment content was adjusted to 4% by mass, and the CTFA content to 47.4% by mass. In Example 122, the black pigment was omitted from the first ink. Consequently, the dispersant was also omitted, and the CTFA content was adjusted to 51.9% by mass.

[0280] Using the first and second inks prepared in Examples 119 to 123, image recording was performed in the same manner as in Example 113, and the same evaluation was conducted. Similar to Example 113, the evaluation results for separation properties, alkali peelability, adhesion, and ethanol resistance in Examples 119 to 123 were all "5".

[0281] It was found that the effect could be obtained regardless of the type of pigment, and regardless of whether pigment was present or not.

[0282] <Examples 301-311, Comparative Examples 301-302> Examples 301 to 311 and Comparative Examples 301 to 302 are examples and comparative examples corresponding to the above-mentioned ink set B.

[0283] [Preparation of the first ink] First, a black pigment dispersion was prepared.

[0284] 25 parts by mass of black pigment (product name "Special Black 250", manufactured by Orion Engineered Carbons), 5 parts by mass of dispersant (product name "SOLSPERSE 32000", manufactured by Lubrizol), 69 parts by mass of cyclic trimethylolpropane formal acrylate (product name "Viscote #200", manufactured by Osaka Organic Chemical Industry) as a dispersion medium, and 1 part by mass of FLORSTAB UV12 (manufactured by Kromachem) were placed in a disperser motor mill M50 (manufactured by Eiger), and the mixture was dispersed using zirconia beads with a diameter of 0.65 mm at a peripheral speed of 9 m / s for 4 hours to obtain a black pigment dispersion.

[0285] Next, the prepared black pigment dispersion was mixed with the polymerizable monomer, polymerization initiator, polymerization inhibitor, and surfactant listed in Table 11 below, so that the content of each component was as indicated in Table 11 (mass%). At this time, the content of the black pigment dispersion was 6.9% by mass. The mixture was stirred using a mixer (product name "L4R", manufactured by Silverson) at 25°C and 5000 rpm for 20 minutes to obtain the first ink.

[0286] [Preparation of the second ink] The polymerizable monomers, polymerization initiators, polymerization inhibitors, and surfactants listed in Table 11 were mixed so that the content of each component matched the content (mass%) listed in Table 11. The mixture was stirred using a mixer (product name "L4R", manufactured by Silverson) at 25°C and 5000 rpm for 20 minutes to obtain the second ink.

[0287] The details of each component listed in Table 11 are as follows: For the ink preparation, Speedcure 7010L (Lambson) and FLORSTAB UV12 (Kromachem) were used. Speedcure 7010L is a mixture of Speedcure 7010 and EOTMPTA, with a mixing ratio of 1:1 by mass. In the table, Speedcure 7010 is listed in the polymerization initiator column, and EOTMPTA is listed in the polymerizable monomer column. Furthermore, FLORSTAB UV12 is a mixture of N-nitroso-N-phenylhydroxylamine aluminum salt and PEA, with a mixing ratio of 1:9. In the table, N-nitroso-N-phenylhydroxylamine aluminum salt is listed in the polymerization inhibitor column, and PEA is listed in the polymerizable monomer column.

[0288] <Polymerizable monomers> - A polymerizable monomer containing a hydroxyl group - • 4-HBA: 4-hydroxybutyl acrylate (product name "4-HBA", manufactured by Osaka Organic Chemical Industry Co., Ltd.) -Polymerizable monomer containing an acidic group- • A-SA: 2-Acryloyloxyethyl succinate (product name "NK Ester A-SA", manufactured by Shin Nakamura Chemical Industry Co., Ltd.) - Other polymerizable monomers • CTFA: Cyclic trimethylolpropane formal acrylate (product name "Viscoat #200", manufactured by Osaka Organic Chemical Industry Co., Ltd.) • 3MPDDA: 3-methyl-1,5-pentanediol diacrylate (product name "SR341", manufactured by Sartomer) • PEA: Phenoxyethyl acrylate, 90% by mass in FLORSTAB UV12 (manufactured by Kromachem) • EOTMPTA: Trimethylolpropane EO-added triacrylate, 50% by mass contained in Speedcure 7010L (Lambson).

[0289] <Polymerization initiator> • Omnirad 819: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (manufactured by IGM Resins BV) Speedcure7010: 1,3-di({α-[1-chloro-9-oxo-9H-thioxanthene-4-yl)oxy]acetylpoly[oxy(1-methylethylene)]}oxy)-2,2-bis({α-[1-methylethylene)]}oxymethyl)propane

[0290] <Polymerization inhibitors> • N-nitroso-N-phenylhydroxylamine aluminum salt, 10% by mass contained in FLORSTAB UV12 (manufactured by Kromachem)

[0291] <Coloring agent> • Black pigment: Special Black 250 (manufactured by Orion Engineered Carbons)

[0292] <Dispersant> • SOLSPERSE32000: Polyethyleneimine-based dispersant (manufactured by Lubrizol)

[0293] <Surfactants> • (Meth)acryloyl group-containing silicone-based surfactant 1: Product name "Tegorad2100" (manufactured by Evonik) • (Meth)acryloyl group-containing silicone-based surfactant 2: Product name "Tegorad2010" (manufactured by Evonik) • (Meth)acryloyl group-containing silicone-based surfactant 3: Product name "Tegorad2500" (manufactured by Evonik)

[0294] [Image Recording] Using an inkjet recording device (product name "CylinderJET", manufactured by Tritech) and an inkjet head (product name "KJ4A-RH", manufactured by Kyocera), the prepared second ink was applied to the body of a PET bottle (product name "PET500 Maru", manufactured by Kokugo). Specifically, the second ink was applied to a surface measuring 7 cm in the longitudinal direction and 5 cm in the circumferential direction of the PET bottle, under conditions of a droplet volume of 11 pL (picoliters) and a resolution of 600 × 600 dpi (dots per inch), recording a 100% solid image with a thickness of 4 μm. Furthermore, under the same conditions as the application of the second ink, the first ink was applied on top of the second ink, recording a 100% solid image with a thickness of 4 μm. After the application of the second ink and after the application of the first ink, an exposure dose of 40 mJ / cm² was used using the LED light source attached to the inkjet recording device. 2 Ultraviolet light was irradiated. A UV-LED irradiator with a peak wavelength of 385 nm (product name "G4B", manufactured by Kyocera Corporation) was used as the LED light source. Then, the PET bottle on which the image was recorded was placed inside the exposure machine. The PET bottle was set horizontally. The exposure machine can rotate the PET bottle. While rotating the entire image recorded on the PET bottle, exposure was performed using the LED light source. The exposure machine and a nitrogen gas generator with a compressor (product name "Maxi-Flow30", manufactured by Inhouse Gas Corporation) were connected at a pressure of 0.2 MPa·s, and nitrogen was flowed so that the oxygen concentration inside the exposure machine was 1 volume% or less. An exposure dose of 500 mJ / cm² was used with the LED light source. 2 The first and second inks were completely cured by irradiating them with ultraviolet light to obtain an image recording. "Complete curing" refers to the process of curing plain paper (for example, Fuji Xerox copy paper C2, product code "V436") under a uniform force (500 mN / cm²). 2 ~1,000 mN / cm 2 The hardening process can be determined by pressing the image with a certain value (within a specified range) and seeing if the image transfers to the paper. In other words, if no transfer occurs at all, it is considered fully hardened.

[0295] [evaluation] For each example and comparative example, the obtained image recordings were used to evaluate alkali peelability, water resistance, storage stability, and discharge properties. The evaluation method is as follows.

[0296] <Alkaline peeling properties> The obtained image recordings were immersed in a 1.5% by mass sodium hydroxide aqueous solution at 85°C, and the peeling state was observed visually. The peeling time was defined as the time from when the image recording was immersed until the ink film completely peeled off from the image recording. The alkali-stripping properties were evaluated based on the peeling time. A shorter peeling time indicates superior alkali-stripping performance. The evaluation criteria are as follows: 8. The peeling time was less than 3 minutes. 7. The peeling time was between 3 and 4 minutes. 6. The peeling time was between 4 and 5 minutes. 5. The peeling time was between 5 minutes and 7 minutes. 4. The peeling time was between 7 and 10 minutes. 3. The peeling time was between 10 and 15 minutes. 2: The peeling time was between 15 and 30 minutes. 1: The peeling time was more than 30 minutes.

[0297] <Water resistance> The obtained image recordings were immersed in deionized water at 10°C to 25°C. After 24 hours, the image recordings were removed from the deionized water. The image surface of the removed image recordings was scratched with a pencil (hardness H) and visually checked for any peeling of the image. If no peeling occurred, the image recordings were immersed in deionized water again, removed after 24 hours, and the image surface was scratched with a pencil (hardness H) again. This procedure was performed up to 9 times. If peeling occurred, the next procedure was not performed. The evaluation criteria are as follows: Rank 5 or higher is considered to be at a level that is acceptable for practical use. 10: No image peeling occurred after 9 operations. 9: After 9 operations, the image peeled off. 8: After 8 operations, the image peeled off. 7: After 7 operations, the image peeled off. 6: After 6 operations, the image peeled off. 5: After 5 operations, the image peeled off. 4: After 4 operations, the image peeled off. 3: After 3 operations, the image peeled off. 2: After two operations, the image peeled off. Image peeling occurred after 1:1 operation.

[0298] <Storage stability> The first prepared ink was filled into glass vials and stored in a 60°C constant temperature bath for 4 weeks. The viscosity increase rate was calculated using the viscosity before storage and the viscosity after 4 weeks of storage. Storage stability was evaluated based on the viscosity increase rate. The evaluation criteria are as follows: Rank 5 or higher indicates a level that is not problematic for practical use. Viscosity increase rate (%) = {(Viscosity after 4 weeks of storage - Viscosity before storage) / Viscosity before storage} × 100 10: Viscosity increase rate is less than 1% 9: Viscosity increase rate is 1% or more but less than 2.5% 8: Viscosity increase rate is 2.5% or more but less than 5% 7: Viscosity increase rate is 2.5% or more but less than 5% 6: Viscosity increase rate is 5% or more but less than 10% 5: Viscosity increase rate is 10% or more but less than 15% 4: Viscosity increase rate is 15% or more but less than 25% 3: Viscosity increase rate is 25% or more but less than 30% 2: Viscosity increase rate is 30% or more but less than 50% 1: Viscosity increase rate of 50% or more

[0299] <Dischargeability> The ejection performance of the first ink was evaluated using an inkjet recording device (product name "CylinderJET", manufactured by Trytech Co., Ltd.) and an inkjet head (product name "KJ4A-RH", manufactured by Kyocera Co., Ltd.). Specifically, the number of ejection nozzles before image recording was counted using a nozzle check pattern. Furthermore, after 10 minutes of continuous printing, the number of ejection nozzles after continuous printing was also counted using a nozzle check pattern. The decrease in the number of ejection nozzles was calculated using the number of ejection nozzles before image recording and the number of ejection nozzles after continuous printing. The same test was performed three times, and the ejection performance was evaluated based on the average value N of the decrease in the number of ejection nozzles. The evaluation criteria are as follows. Decrease in the number of ejection nozzles = Number of ejection nozzles before image recording - Number of ejection nozzles after continuous printing 10: N is less than 1. 9: N is between 1 and 2 (inclusive). 8: N is greater than or equal to 2 and less than 3. 7: N is 3 or greater and less than 4. 6: N is 4 or greater and less than 5. 5: N is between 5 and 7 (inclusive). 4: N is between 7 and 10 (inclusive). 3: N is between 10 and 15 (inclusive). 2: N is between 15 and 20 (inclusive). 1: N is 20 or greater.

[0300] Table 11 shows the evaluation results.

[0301] In Table 11, "Acid group-containing monomer + Hydroxyl group-containing monomer" in the "Second Ink" column refers to the total content of polymerizable monomers containing acid groups and polymerizable monomers containing hydroxyl groups in the Second Ink. "Hydroxy group-containing monomer in First Ink / (Acid group-containing monomer in Second Ink + Hydroxyl group-containing monomer)" refers to the mass ratio of the content of polymerizable monomers containing hydroxyl groups in the First Ink to the total content of polymerizable monomers containing acid groups and polymerizable monomers containing hydroxyl groups in the Second Ink, assuming the First Ink and the Second Ink are of equal mass.

[0302] [Table 11]

[0303] As shown in Table 11, Examples 301 to 311 were found to have excellent alkali-peelability and water resistance because they comprised a first ink containing a colorant and a polymerizable monomer having a hydroxyl group, and a second ink containing a polymerizable monomer having an acid group.

[0304] In Comparative Example 301, it was found that the second ink did not contain polymerizable monomers having acidic groups and had poor alkali-removable properties. In Comparative Example 302, it was found that the first ink did not contain polymerizable monomers having hydroxyl groups and exhibited poor alkali-peelability and water resistance.

[0305] In Example 301, the content of polymerizable monomers having hydroxyl groups was 30% to 70% by mass relative to the total amount of the first ink, and it was found to have superior alkali peelability and water resistance compared to Example 302.

[0306] In Example 301, the content of polymerizable monomers having acidic groups was 5% to 25% by mass relative to the total amount of the second ink, and it was found to have superior alkali-peelability and water resistance compared to Examples 309 and 310.

[0307] In Example 301, the second ink further contained a polymerizable monomer having a hydroxyl group, and it was found to have superior alkali-removable properties compared to Example 308.

[0308] In Example 301, the total content of polymerizable monomers having acidic groups and polymerizable monomers having hydroxyl groups in the second ink was 10% to 50% by mass relative to the total amount of the second ink, and it was found to have superior water resistance compared to Example 307.

[0309] In Example 301, when the first ink and the second ink were of equal mass, the mass ratio of the hydroxyl group polymerizable monomer content in the first ink to the total content of acid group polymerizable monomers and hydroxyl group polymerizable monomers in the second ink was 1 or more, indicating superior water resistance compared to Example 307. Furthermore, in Example 301, the above mass ratio was 4 or less, indicating superior alkali peelability and water resistance compared to Example 311.

[0310] <Examples 321-324> In Examples 321 to 324, the first and second inks were prepared in the same manner as in Example 301, except that the black pigment in the first ink was changed to the following. Specifically, in Example 321, a cyan pigment dispersion was prepared in the same manner as in Example 301, except that the black pigment in the first ink was replaced with a cyan pigment (product name "Heliogen® Blue D 7110 F", manufactured by BASF). The first ink (cyan ink) was obtained in the same manner as in Example 301, except that the content of the cyan pigment dispersion was changed to 9.5% by mass and the content of 3MPDDA was changed to 14.5% by mass.

[0311] In Example 322, a magenta pigment dispersion was prepared in the same manner as in Example 301, except that the black pigment in the first ink was replaced with a magenta pigment (product name "CINQUASIA MAGENTA RT-355D", manufactured by BASF). The first ink (magenta ink) was obtained in the same manner as in Example 301, except that the content of magenta pigment dispersion was changed to 18% by mass, the content of 3MPDDA to 8% by mass, and the content of Speedcure7010L to 2% by mass.

[0312] In Example 323, a yellow pigment dispersion was prepared in the same manner as in Example 301, except that the black pigment in the first ink was replaced with a yellow pigment (product name "NOVOPERM YELLOW H2G", manufactured by Clariant). The first ink (yellow ink) was obtained in the same manner as in Example 301, except that the content of the yellow pigment dispersion was changed to 12.1% by mass and the content of 3MPDDA was changed to 11.9% by mass.

[0313] In Example 324, a white pigment dispersion was prepared in the same manner as in Example 301, except that the black pigment in the first ink was replaced with a white pigment (product name "KRONOS 2300", manufactured by KRONOS), the dispersant was replaced with SOLSPERSE 41000 (manufactured by Lubrizol), and the white pigment content was changed to 35% by mass, the dispersant content to 7% by mass, and the CTFA content to 57% by mass. The first ink (white ink) was obtained in the same manner as in Example 301, except that the content of the white pigment dispersion was changed to 30% by mass, the content of 3MPDDA to 1.6% by mass, the content of Omnirad 819 to 3.4% by mass, the content of Speedcure 7010L to 0% by mass, and the content of polymerizable silicone surfactant 2 to 3% by mass.

[0314] Using the first and second inks prepared in Examples 321 to 324, image recording was performed in the same manner as in Example 301, and the same evaluation was conducted. Examples 321 to 324 also obtained the same evaluation results as Example 301.

[0315] It was found that the effect could be obtained regardless of the type of pigment used.

[0316] Furthermore, the disclosures of Japanese Patent Application No. 2021-073511, filed on April 23, 2021, and Japanese Patent Application No. 2021-181158, filed on November 5, 2021, are incorporated herein by reference in their entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated as being incorporated by reference.

Claims

1. It comprises a polymerizable monomer and a polymerizable surfactant, The polymerizable monomer is an active energy ray curable inkjet ink for beverage containers, comprising a polymerizable monomer having an acid group.

2. The polymerizable monomer includes a polyfunctional monomer, The content of the polyfunctional monomer is 25% by mass or more of the total amount of the active energy ray curable inkjet ink for beverage containers according to claim 1.

3. The active energy ray curable inkjet ink for beverage containers according to claim 2, wherein the mass ratio of the content of the polyfunctional monomer to the content of the polymerizable surfactant is 4 to 80.

4. The polymerizable monomer includes a monofunctional monomer. The content of the monofunctional monomer is 60% by mass or more of the total amount of the active energy ray curable inkjet ink for beverage containers according to claim 1.

5. The active energy ray curable inkjet ink for beverage containers according to claim 4, wherein the mass ratio of the content of the monofunctional monomer to the content of the polymerizable surfactant is 3 to 100.

6. The active energy ray curable inkjet ink for beverage containers according to claim 1, wherein the mass ratio of the content of the polymerizable monomer having an acid group to the content of the polymerizable surfactant is 0.2 to 10.

7. The polymerizable monomer comprises a polymerizable monomer having a specific gravity of 1.0 or less, as described in claim 1, for active energy ray curable inkjet ink for beverage containers.

8. The polymerizable surfactant is a silicone-based surfactant having a (meth)acryloyl group, as described in claim 1, for active energy ray-curable inkjet ink for beverage containers.

9. The polymerizable surfactant is a compound that exhibits a surface tension reduction of 5 mN / m or more relative to cyclic trimethylolpropane formal acrylate, as described in claim 1.

10. The polymerizable surfactant comprises polymerizable surfactant A with a logP value of 4 or more, and polymerizable surfactant B with a logP value of less than 4, as described in claim 1, for active energy ray curable inkjet ink for beverage containers.

11. A step of applying an active energy ray curable inkjet ink for beverage containers, as described in any one of claims 1 to 10, to the surface of a beverage container using an inkjet recording method, An image recording method comprising the step of irradiating an applied ink with active energy rays.

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