WO2022224839A1

WO2022224839A1 - Active energy ray-curable primer coating composition, ink set, and image recording method

Info

Publication number: WO2022224839A1
Application number: PCT/JP2022/017270
Authority: WO
Inventors: 健次郎荒木
Original assignee: 富士フイルム株式会社
Priority date: 2021-04-23
Filing date: 2022-04-07
Publication date: 2022-10-27

Abstract

The present invention provides an active energy ray-curable primer coating composition which contains a monofunctional polymerizable monomer A1 that comprises at least one structure selected from the group consisting of a cyclic ether structure and an alicyclic structure, while having an SP value of 17.5 MPa^1/2 to 23.0 MPa^1/2, wherein: the content of the monofunctional polymerizable monomer A1 is 45% by mass or more relative to the total amount of the primer coating composition; and any multifunctional polymerizable compound is not contained therein, or the content of multifunctional polymerizable compounds is 25% by mass or less relative to the total amount of the primer coating composition. The present invention also provides applications of this active energy ray-curable primer coating composition.

Description

Active energy ray-curable undercoat composition, ink set, and image recording method

The present disclosure relates to an active energy ray-curable undercoat composition, an ink set, and an image recording method.

Conventionally, when recording an image using ink on a base material, a method of curing using active energy rays is known.

For example, JP-A-2017-214481 describes a photocurable inkjet primer ink composition containing a photopolymerizable compound and a photopolymerization initiator and having a viscosity of 5.0 to 10.0 mPa s at 25°C. The photopolymerizable compound consists of a monofunctional ethylenically unsaturated monomer and a bifunctional ethylenically unsaturated oligomer, and the content of the monofunctional ethylenically unsaturated monomer is based on 100 parts by weight of the entire composition. is 76.0 parts by weight or more, and the homopolymer of the monofunctional ethylenically unsaturated monomer has a glass transition temperature of less than 25°C. Japanese Patent Application Laid-Open No. 2019-56114 discloses an energy beam-curable inkjet ink composition containing a polymerizable monomer, wherein the polymerizable monomer is a monofunctional monomer having an aromatic hydrocarbon-based cyclic structure in the molecule and It contains a monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure in the molecule, and 90% by mass or more of the polymerizable monomer is a monofunctional monomer, and a monofunctional having an aromatic hydrocarbon-based cyclic structure. An energy ray-curable inkjet ink composition containing a monomer and a monofunctional monomer other than the monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure is disclosed. In JP-A-2020-55901, an alicyclic monofunctional (meth)acrylate (A) having a glass transition temperature of 0 to 150° C. and a hydroxyl group-containing monofunctional having a glass transition temperature of −100 to 0° C. ( A meth)acrylate (B), a trifunctional or higher polyfunctional (meth)acrylate (C) having a (meth)acrylic equivalent of 100 to 250, and a photopolymerization initiator (D), and a polyfunctional (meth) An active energy ray-curable inkjet ink composition is described in which the content of acrylate (C) is from more than 15% by mass to 30% by mass or less with respect to the total amount. JP 2014-148673 A contains an active energy ray-polymerizable monomer and an active energy ray-polymerization initiator, and as the active energy ray-polymerizable monomer, monomer A): a glass transition point of −30° C. or less a monofunctional monomer;
Monomer B): an active energy ray-curable ink composition containing a polyfunctional monomer having a glass transition point of 0° C. or lower.

In some cases, it is required to form an ink film with excellent adhesion to the substrate in the image recorded matter obtained by applying the ink onto the substrate.

The present disclosure has been made in view of such circumstances, and according to embodiments of the present invention, an active energy ray-curable undercoat composition capable of forming an ink film having excellent adhesion to a substrate. , an ink set, and an image recording method are provided.

The present disclosure includes the following aspects.
<1> Monofunctional polymerizable having an SP value of 17.5 MPa ^1/2 to 23.0 MPa ^1/2 and containing at least one structure selected from the group consisting of a cyclic ether structure and an alicyclic structure It contains a monomer A1, the content of the monofunctional polymerizable monomer A1 is 45% by mass or more with respect to the total amount of the active energy ray-curable undercoat composition, and does not contain a polyfunctional polymerizable compound, or An active energy ray-curable undercoat composition, wherein the content of the polyfunctional polymerizable compound is more than 0% by mass and 25% by mass or less relative to the total amount of the active energy ray-curable undercoat composition.
<2> The active energy ray-curable undercoat composition according to <1>, wherein the monofunctional polymerizable monomer A1 has a glass transition temperature of −10° C. to 40° C. when converted into a homopolymer.
<3> The active energy ray-curable undercoat composition according to <1> or <2>, wherein the monofunctional polymerizable monomer A1 contains a cyclic ether structure.
<4> The active energy ray-curable undercoat composition according to any one of <1> to <3>, further comprising a polyester resin.
<5> The active energy ray-curable undercoat composition according to <4>, wherein the polyester resin has an acid value of 3 mgKOH/g to 14 mgKOH/g.
<6> The active energy ray-curable undercoat composition according to <4> or <5>, wherein the polyester resin has a hydroxyl value of 20 mgKOH/g or more.
<7> The active energy ray-curable undercoat composition according to any one of <4> to <6>, wherein the polyester resin has a weight average molecular weight of 10,000 or less.
<8> The active energy ray-curable undercoat composition according to any one of <4> to <7>, wherein the polyester resin has a glass transition temperature of 30°C to 65°C.
<9> The active energy ray-curable undercoat according to any one of <4> to <8>, wherein the mass ratio of the content of the monofunctional polymerizable monomer A1 to the content of the polyester resin is 8 to 100. Composition.
<10> The active energy ray-curable undercoat composition according to any one of <1> to <9>, further comprising a monofunctional polymerizable monomer A2 having an acid group.
<11> The active energy ray-curable undercoat composition according to any one of <4> to <9>, further comprising a polyester resin and a monofunctional polymerizable monomer A2 having an acid group.
<12> The total content of the monofunctional polymerizable monomer A1 and the monofunctional polymerizable monomer A2 having an acid group is 60% by mass or more relative to the total amount of the active energy ray-curable undercoat composition. <10> Or the active energy ray-curable undercoat composition according to <11>.
<13> The active energy ray-curable undercoat composition according to <11>, wherein the mass ratio of the content of the monofunctional polymerizable monomer A2 having an acid group to the content of the polyester resin is 1-10.
<14> The active energy ray-curable undercoat composition according to any one of <1> to <13>, an active energy ray-curable ink containing a polyfunctional polymerizable monomer,
Ink set with
<15> When the active energy ray-curable undercoat composition and the active energy ray-curable ink have the same mass, the active energy ray-curable undercoat with respect to the content of the polyfunctional polymerizable monomer in the active energy ray-curable ink The ink set according to <14>, wherein the content of the monofunctional polymerizable monomer A1 in the composition has a mass ratio of 1 to 3.
<16> When the active energy ray-curable undercoat composition according to any one of <10> to <13> is provided, and the active energy ray-curable undercoat composition and the active energy ray-curable ink have the same mass. , the mass ratio of the content of the polyfunctional polymerizable monomer in the active energy ray-curable ink to the content of the monofunctional polymerizable monomer A2 in the active energy ray-curable undercoat composition is 1 to 20, < The ink set according to 14> or <15>.
<17> The active energy ray-curable undercoat composition according to <4> to <9>, <11>, or <13> is provided, and the active energy ray-curable undercoat composition and the active energy ray-curable ink are used in the same manner. When expressed as mass, the mass ratio of the content of the polyfunctional polymerizable monomer in the active energy ray-curable ink to the content of the polyester resin in the active energy ray-curable undercoat composition is 5 to 50. The ink set according to 14> or <15>.
<18> The ink set according to any one of <14> to <17> is used,
A step of applying an active energy ray-curable undercoat composition onto a substrate by an inkjet recording method, a step of irradiating the active energy ray-curable undercoat composition with a first active energy ray, and a step of irradiating the first active energy ray. An image comprising a step of applying an active energy ray-curable ink on the active energy ray-curable undercoat composition by an inkjet recording method, and a step of irradiating the active energy ray-curable ink with a second active energy ray. Recording method.

According to the present disclosure, an active energy ray-curable undercoat composition, an ink set, and an image recording method capable of forming an ink film with excellent adhesion to a substrate are provided.

The active energy ray-curable undercoat composition, ink set, and image recording method of the present disclosure will be described in detail below.

In this specification, the numerical range indicated using "to" means a range including the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described stepwise in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described stepwise. Moreover, in the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the values shown in the examples.

As used herein, the amount of each component in the composition refers to the total amount of the multiple substances present in the composition when there are multiple substances corresponding to each component in the composition, unless otherwise specified. means
In the present specification, a combination of two or more preferred aspects is a more preferred aspect.
In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. be

As used herein, the term "image" means a film in general formed by applying ink, and the term "image recording" means formation of an image (that is, a film).
The concept of "image" in this specification also includes a solid image.

As used herein, "(meth)acrylate" is a concept that includes both acrylate and methacrylate. Moreover, "(meth)acryl" is a concept that includes both acryl and methacryl.

The active energy ray-curable undercoat composition of the present disclosure (hereinafter also simply referred to as “undercoat composition”) has an SP value of 17.5 MPa ^1/2 to 23.0 MPa ^1/2 , and has a cyclic ether structure and It contains a monofunctional polymerizable monomer A1 containing at least one structure selected from the group consisting of alicyclic structures, and the content of the monofunctional polymerizable monomer A1 is 45 mass with respect to the total amount of the undercoat composition. % or more and contains no polyfunctional polymerizable compound, or the content of the polyfunctional polymerizable compound is 25% by mass or less with respect to the total amount of the undercoat composition.

For example, the undercoat composition of the present disclosure is applied onto a substrate, then irradiated with an active energy ray, and further applied with an ink (and, if necessary, irradiated with an active energy ray after application of the ink). An image recorded matter in which an ink film is formed as an image on the material can be obtained. The undercoat composition of the present disclosure can be used to form an ink film with excellent adhesion. The reason for this is presumed as follows.

The monofunctional polymerizable monomer A1 contained in the undercoat composition of the present disclosure has an SP value of 17.5 MPa ^1/2 to 23.0 MPa ^1/2 and is selected from the group consisting of a cyclic ether structure and an alicyclic structure. Include at least one selected structure. Since the SP value of the monofunctional polymerizable monomer A1 is close to the SP value of the substrate (eg, polyethylene terephthalate), the adhesion is improved. Further, a monomer having a ring structure tends to have a high glass transition temperature, and the elasticity and viscosity of the ink film are well balanced, so that the adhesion to the substrate is improved. Thus, it is considered that the content of the monofunctional polymerizable monomer A1 that contributes to the improvement of the adhesion to the substrate is 45% by mass or more, thereby obtaining the adhesion to the substrate. Furthermore, when a polyfunctional polymerizable compound is contained, curing shrinkage and residual stress are likely to occur in the polymerization reaction caused by irradiation with active energy rays after application of the undercoat composition. When the content of the polyfunctional polymerizable compound is 25% by mass or less, the residual stress can be suppressed to a low level, so it is considered that the adhesiveness to the substrate is excellent.

On the other hand, JP-A-2017-214481 and JP-A-2020-55901 do not describe an undercoat composition containing a monofunctional polymerizable monomer having the above SP value and structure. Further, in the undercoat composition described in JP-A-2019-56114 and JP-A-2014-148673, since the content of the compound corresponding to the monofunctional polymerizable monomer A1 is less than 45% by mass, adhesion There is still room for improvement in sexuality.

Each component contained in the active energy ray-curable undercoat composition of the present disclosure will be described below.

[Active energy ray-curable undercoat composition]
The undercoat composition of the present disclosure has an SP value of 17.5 MPa ^1/2 to 23.0 MPa ^1/2 and has at least one structure selected from the group consisting of a cyclic ether structure and an alicyclic structure. containing a monofunctional polymerizable monomer A1, the content of the monofunctional polymerizable monomer A1 is 45% by mass or more with respect to the total amount of the undercoat composition, and does not contain a polyfunctional polymerizable compound, or The content of the polyfunctional polymerizable compound is 25% by mass or less with respect to the total amount of the undercoat composition.

The undercoat composition of the present disclosure is an active energy ray-curable undercoat composition. That is, the undercoat composition of the present disclosure is cured by irradiation with active energy rays. Examples of active energy rays include γ rays, β rays, electron beams, ultraviolet rays, and visible rays. Among them, the active energy rays are preferably ultraviolet rays. The primer composition of the present disclosure is preferably an ultraviolet curable primer composition.

<Monofunctional polymerizable monomer A1>
The undercoat composition of the present disclosure has an SP value of 17.5 MPa ^1/2 to 23.0 MPa ^1/2 and has at least one structure selected from the group consisting of a cyclic ether structure and an alicyclic structure. contains a monofunctional polymerizable monomer A1 containing Hereinafter, "a monofunctional polymerizable structure having an SP value of 17.5 MPa ^1/2 to 23.0 MPa ^1/2 and containing at least one structure selected from the group consisting of a cyclic ether structure and an alicyclic structure "monomer" is also simply referred to as "monofunctional monomer A1".

In the present disclosure, "monomer" refers to a compound with a molecular weight of less than 1000. Molecular weight can be calculated from the type and number of elements constituting the compound

In the present disclosure, "polymerizable monomer" refers to a monomer having a polymerizable group.

In the present disclosure, "monofunctional polymerizable monomer" refers to a monomer having one polymerizable group.

The polymerizable group in the monofunctional monomer A1 may be a cationically polymerizable group or a radically polymerizable group, but is preferably a radically polymerizable group from the viewpoint of curability. From the viewpoint of curability, the radically polymerizable group is preferably an ethylenically unsaturated group, more preferably a (meth)acryloyl group. That is, monofunctional monomer A1 is more preferably a monofunctional (meth)acrylate.

In the monofunctional monomer A1, the cyclic ether structure includes, for example, a furan ring structure, a pyran ring structure, an oxirane ring structure, an oxetane ring structure, a dioxane ring structure, a dioxolane ring structure, and a morpholine ring structure.

Although the number of carbon atoms forming the ring of the alicyclic structure in the monofunctional monomer A1 is not particularly limited, it is preferably 5-10. Alicyclic structures include, for example, cyclohexane ring structures, dicyclopentanyl ring structures, dicyclopentenyl ring structures, norbornane ring structures, isobornane ring structures, norbornene ring structures, isobornene ring structures, and adamantane ring structures.

Examples of monofunctional polymerizable monomers containing at least one structure selected from the group consisting of cyclic ether structures and alicyclic structures include the following compounds. Examples of the monofunctional monomer A1 include compounds having an SP value of 17.5 MPa ^1/2 to 23.0 MPa ^1/2 among the compounds exemplified below.

Among them, the monofunctional monomer A1 preferably has an SP value of 17.5 MPa ^1/2 to 20.0 MPa ^1/2 from the viewpoint of further improving the adhesion to the substrate.

In the present disclosure, the SP value shall use the Hansen Solubility Parameter. The Hansen solubility parameter is the solubility parameter introduced by Hildebrand divided into three components, the dispersion term δd, the polar term δp, and the hydrogen bonding term δh, and expressed in three-dimensional space. . In the present disclosure, the SP value is represented by δ[MPa ^1/2 ] and is a value calculated using the following formula.
δ[MPa ^1/2 ]=(δd ² +δp ² +δh ² ) ^1/2

In addition, the dispersion term δd, the polar term δp, and the hydrogen bonding term δh have been sought by Hansen and his successors, and are detailed in Polymer Handbook (fourth edition), VII-698-711.

Also, the monofunctional monomer A1 preferably contains a cyclic ether structure. The presence of a cyclic ether structure tends to reduce odor.

The monofunctional monomer A1 preferably has a glass transition temperature of -10°C to 150°C, more preferably -10°C to 120°C, and -10°C to 40°C when homopolymerized. is more preferred, and 10°C to 40°C is particularly preferred. When the glass transition temperature is −10° C. or higher, the adhesiveness to the substrate is improved. Further, when the glass transition temperature is 150° C. or less, the adhesiveness to the substrate is improved.

When the undercoat composition contains a plurality of monofunctional monomers A1, the average value of the glass transition temperatures of homopolymers is preferably within the above range. That is, for the monofunctional monomer A1 contained in the undercoat composition, the glass transition temperature of each homopolymer is measured, the average value of the measured values is calculated, and the calculated value is preferably within the above range.

The glass transition temperature when the monofunctional monomer A1 is a homopolymer is measured by the following method. First, a homopolymer having a weight average molecular weight of 10,000 to 20,000 is produced using monofunctional monomer A1. The glass transition temperature of the produced homopolymer is measured according to the method described in JIS K7121:2012.
The glass transition temperature is measured using a differential scanning calorimeter, for example, using the product name "DSC-60" manufactured by Shimadzu Corporation.

In the present disclosure, the weight average molecular weight is measured using gel permeation chromatography (GPC). For example, HLC-8220GPC (manufactured by Tosoh Corporation) is used as GPC, three columns of TSKgel, Super Multipore HZ-H (manufactured by Tosoh Corporation, 4.6 mm ID × 15 cm) are used, and THF (tetrahydrofuran) is used as an eluent. use. The conditions are a sample concentration of 0.45% by mass, a flow rate of 0.35 ml/min, a sample injection amount of 10 μl, a measurement temperature of 40° C., and detection using a differential refractive index (RI) detector. For the calibration curve, as a standard sample, the product name "TSK standard polystyrene" manufactured by Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", Eight samples of "A-2500", "A-1000" and "n-propylbenzene" are used. The glass transition temperature of the homopolymer varies depending on the weight average molecular weight of the homopolymer, but when the weight average molecular weight is 10,000 to 20,000, the variation is negligibly small.

The content of the monofunctional monomer A1 in the undercoat composition is 45% by mass or more with respect to the total amount of the undercoat composition, and from the viewpoint of adhesion to the substrate, it is 60% by mass to 80% by mass. is preferred, and 65% by mass to 80% by mass is more preferred.

<Polyester resin>
Preferably, the primer composition of the present disclosure further comprises at least one polyester resin. When the undercoat composition contains a polyester resin, the adhesion to the substrate is improved. This is probably because the polyester resin suppresses the generation of residual stress due to cure shrinkage.

"Polyester resin" means a polymer having an ester bond in its main chain. A polyester resin is usually obtained by reacting a dicarboxylic acid and a polyol. Dicarboxylic acids include, for example, fumaric acid, itaconic acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid, sulfoisophthalic acid, naphthalenedicarboxylic acid, tetrahydrophthalic acid, and cyclohexanedicarboxylic acid. Polyols include, for example, ethylene glycol, propylene glycol, glycerin, hexanetriol, butanediol, hexanediol, and 1,4-cyclohexanedimethanol, bisphenol A, and hydrogenated bisphenol A.

Among them, the polyester resin is preferably a polyester resin obtained by reacting a dicarboxylic acid having a ring structure with a polyol having a ring structure. Examples of such polyester resins include Diaclone FC1588 (manufactured by Mitsubishi Chemical), Nichigo Polyester TP219 (manufactured by Mitsubishi Chemical), UVAD081 (manufactured by Osaka Soda), and Diaclone ER-535 (manufactured by Mitsubishi Chemical). ).

Polyester resins and raw materials for polyester resins are described, for example, in "Polyester Resin Handbook" (written by Eiichiro Takiyama, Nikkan Kogyo Shimbun, published in 1988).

Examples of polyester resins include polyhydroxybutyrate (PHB), polycaprolactone (PCL), polycaprolactone butylene succinate, polybutylene succinate (PBS), and polybutylene succinate adipate (PBSA). , polybutylene succinate carbonate, polyethylene terephthalate succinate, polybutylene adipate terephthalate, polytetramethylene adipate terephthalate, polybutylene adipate terephthalate, polyethylene succinate (PES), polyglycolic acid (PGA), and Examples include polylactic acid (PLA)-based polyesters, carbonate copolymers of aliphatic polyesters, and copolymers of aliphatic polyesters and polyamides.

In the present disclosure, the polyester resin preferably has an acid value of 0.5 mgKOH/g to 20 mgKOH/g, more preferably 3 mgKOH/g to 14 mgKOH/g, and 5 mgKOH/g to 12 mgKOH/g. is more preferred. When the acid value is 0.5 mgKOH/g or more, the alkali peelability is improved. On the other hand, when the acid value is 20 mgKOH/g or less, the adhesion to the substrate is improved.

In the present disclosure, the acid value is a value measured by the method described in JIS K0070:1992.

In the present disclosure, the polyester resin preferably has a hydroxyl value of 20 mgKOH/g or more, more preferably 40 mgKOH/g or more. When the hydroxyl value is 20 mgKOH/g or more, the adhesion to the substrate is improved. The upper limit of the hydroxyl value is not particularly limited, and is, for example, 80 mgKOH/g.

In the present disclosure, the hydroxyl value is expressed in mg of potassium hydroxide required to neutralize acetic acid generated when 1 g of polyester resin is acetylated.

In the present disclosure, the polyester resin preferably has a weight average molecular weight (Mw) of 20,000 or less, more preferably 10,000 or less, and even more preferably 8,000 or less. When the weight average molecular weight is 20,000 or less, the adhesiveness to the substrate is improved. The lower limit of the weight average molecular weight is not particularly limited, and is 1,000, for example.

In the present disclosure, the polyester resin preferably has a glass transition temperature (Tg) of 5°C to 75°C, more preferably 30°C to 65°C. When the glass transition temperature is 30°C or higher, the adhesiveness to the substrate is improved. Further, when the glass transition temperature is 65° C. or less, the adhesiveness to the substrate is improved.

The polyester resin may be a commercially available product. Table 2 shows the acid value, hydroxyl value, weight average molecular weight Mw, and glass transition temperature Tg of commercially available polyester resins.

When the undercoat composition contains a polyester resin, the content of the polyester resin is preferably 0.5% by mass to 15% by mass, and 3% by mass to 10% by mass, based on the total amount of the undercoat composition. is more preferable.

<Monofunctional polymerizable monomer A2 having an acid group>
Preferably, the undercoat composition of the present disclosure further comprises a monofunctional polymerizable monomer A2 having an acid group. Hereinafter, the "monofunctional polymerizable monomer having an acid group" is referred to as "monofunctional monomer A2".

In addition, the SP value is 17.5 MPa ^1/2 to 23.0 MPa ^1/2 , and contains at least one structure selected from the group consisting of a cyclic ether structure and an alicyclic structure, and an acid group is the monofunctional monomer A1, and the monofunctional monomer A1 and the monofunctional monomer A2 are distinguished from each other.

Examples of acid groups in the monofunctional monomer A2 include carboxy groups, sulfo groups, phosphonic acid groups, phosphoric acid groups, and sulfonamide groups.

Examples of polymerizable monomers having a carboxy group include 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethylhexahydrophthalate, 2-( meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-carboxyethyl (meth)acrylate, and (meth)acrylic acid.

Polymerizable monomers having a sulfo group include, for example, 2-hydroxy-3-sulfopropyl(meth)acrylate, 2-(meth)acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl(meth)acrylate, 3-sulfo Propyl (meth)acrylate, and 4-styrenesulfonic acid.

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

Among them, the monofunctional monomer A2 is preferably a monofunctional polymerizable monomer having a carboxy group.

The polymerizable group in the monofunctional monomer A2 may be a cationically polymerizable group or a radically polymerizable group, but is preferably a radically polymerizable group from the viewpoint of curability. From the viewpoint of curability, the radically polymerizable group is preferably an ethylenically unsaturated group, more preferably a (meth)acryloyl group. That is, the monofunctional monomer A2 is more preferably a monofunctional (meth)acrylate, more preferably a monofunctional (meth)acrylate having a carboxy group.

Acid groups improve their water solubility when they react with alkalis to form salts. Therefore, when the undercoat composition contains the monofunctional monomer A2, the alkali peelability is improved.

When the undercoat composition contains a monofunctional monomer A2, the content of the monofunctional monomer A2 is preferably 1% by mass to 50% by mass, based on the total amount of the undercoat composition, and 2% by mass to 15% by mass. is more preferable.

The undercoat composition of the present disclosure preferably further contains a polyester resin and a monofunctional monomer A2. When both the polyester resin and the monofunctional monomer A2 are contained in the polyester resin and the monofunctional monomer A2, the adhesiveness to the substrate and the alkali releasability are improved.

<Surfactant>
Preferably, the primer composition of the present disclosure further comprises at least one surfactant. The type of surfactant is not particularly limited, and may be an anionic surfactant, a cationic surfactant, or a nonionic surfactant.

Above all, from the viewpoint of adhesion to the substrate, the surfactant is preferably a surfactant having a polymerizable group (hereinafter also referred to as "polymerizable surfactant").

The polymerizable group in the polymerizable surfactant may be a cationically polymerizable group or a radically polymerizable group, but from the viewpoint of curability, it is preferably a radically polymerizable group. Moreover, the radically polymerizable group is preferably an ethylenically unsaturated group from the viewpoint of curability. Among them, the polymerizable group in the polymerizable surfactant is preferably a vinyl group or a (meth)acryloyl group, and more preferably a (meth)acryloyl group from the viewpoint of ethanol resistance.

From the viewpoint of image quality, the number of polymerizable groups in the polymerizable surfactant is preferably 2 or more, more preferably 3 or more. Although the upper limit of the number of polymerizable groups in the polymerizable surfactant is not particularly limited, it is, for example, 5 from the viewpoint of ejection properties when the ink is ejected by an inkjet recording method.

That is, with respect to the type and number of polymerizable groups, the polymerizable surfactant is preferably a surfactant having two or more (meth)acryloyl groups, and an interface having three or more (meth)acryloyl groups More preferably, it is an active agent.

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

Examples of polymerizable silicone-based surfactants include compounds in which a polymerizable group is bonded to the main chain or side chain of polyether-modified dimethylsiloxane.

Examples of commercially available polymerizable silicone surfactants include BYK-UV3500, 3505, 3530, 3570, 3575, 3576 (manufactured by BYK), Tegorad 2100, 2200, 2250, 2300, 2500, 2600, 2700, 2800, 2010, 2011 (manufactured by Evonik), EBECRYL350, 1360 (manufactured by Daicel Allnex), KP-410, 411, 412, 413, 414, 415, 416, 418, 420, 422, 423 (manufactured by Shin-Etsu Silicone Co., Ltd.), etc. and a silicone surfactant having a (meth)acryloyl group.

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

Commercially available polymerizable fluorosurfactants include, for example, MEGAFACE RS-56, RS-72-K, RS-75, RS-76-E, RS-65-NS, RS-78 and RS-90. Fluorinated surfactants having a (meth)acryloyl group, such as (manufactured by DIC).

Examples of polymerizable acrylic surfactants include compounds in which a polymerizable group is bonded to the side chain of a poly(meth)acrylic structure.

Commercially available polymerizable acrylic surfactants include, for example, CN821 (manufactured by Sartomer).

The surfactant is preferably a polymerizable silicone surfactant, more preferably a silicone surfactant having a (meth)acryloyl group.

When the undercoat composition contains a surfactant, the content of the surfactant is preferably 0.1% by mass to 15% by mass with respect to the total amount of the undercoat composition.

<Other polymerizable compounds>
The undercoat composition of the present disclosure may contain polymerizable compounds other than the monofunctional monomer A1 and the monofunctional monomer A2. A polymerizable compound other than the monofunctional monomer A1 and the monofunctional monomer A2 may be a monofunctional polymerizable compound or a polyfunctional polymerizable compound. Other polymerizable compounds may be monomers with a molecular weight of 1,000 or less, or oligomers or polymers with a molecular weight of more than 1,000.

The undercoat composition of the present disclosure does not contain a polyfunctional polymerizable compound, or the content of the polyfunctional polymerizable compound is more than 0% by mass and 25% by mass or less with respect to the total amount of the undercoat composition.

In the present disclosure, the term "monofunctional polymerizable compound" refers to a compound having one polymerizable group, and the term "polyfunctional polymerizable compound" refers to a compound having two or more polymerizable groups. .

If the undercoat composition contains a polyfunctional polymerizable compound, curing shrinkage and residual stress are likely to occur in the polymerization reaction caused by irradiation with active energy rays after applying the undercoat composition. When the content of the polyfunctional polymerizable compound is 25% by mass or less, the residual stress is small, so it is considered that the adhesiveness to the substrate is excellent. The content of the polyfunctional polymerizable compound is preferably 10 mass % or less, more preferably 2 mass % to 8 mass %.

The polymerizable group in the other polymerizable compound that may be contained in the undercoat composition of the present disclosure may be a cationically polymerizable group or a radically polymerizable group, but from the viewpoint of curability, A radically polymerizable group is preferred. Moreover, the radically polymerizable group is preferably an ethylenically unsaturated group from the viewpoint of curability.

-Other monofunctional polymerizable compounds-
Other monofunctional polymerizable compounds include, for example, monofunctional (meth)acrylates, monofunctional (meth)acrylamides, monofunctional aromatic vinyl compounds, monofunctional vinyl ethers and monofunctional N-vinyl compounds.

Examples of monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, and 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 acrylates, 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-Methoxyethoxy)ethyl (meth)acrylate, 2-(2-butoxyethoxy)ethyl (meth)acrylate, 2,2,2-tetrafluoroethyl (meth)acrylate, 1H,1H,2H,2H-perfluoro Decyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4,5-tetramethylphenyl (meth)acrylate, 4-chlorophenyl (meth)acrylate, 2-phenoxymethyl (meth)acrylate acrylates, 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 ) acrylate, cyclic trimethylolpropane formal (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 Succinic acid, 2-methacryloyloxyhexahydrophthalic acid, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, ethoxydiethylene glycol (meth)acrylate, butoxydiethyleneglycol (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.

Examples of monofunctional (meth)acrylamides include (meth)acrylamide, N-methyl(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)acryloylmorpholine.

Examples of monofunctional aromatic vinyl compounds include styrene, dimethylstyrene, trimethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, vinylbenzoic acid methyl ester, 3-methyl Styrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4-hexylstyrene, 3-octyl Styrene, 4-octylstyrene, 3-(2-ethylhexyl)styrene, 4-(2-ethylhexyl)styrene, allylstyrene, isopropenylstyrene, butenylstyrene, octenylstyrene, 4-t-butoxycarbonylstyrene and 4- t-butoxystyrene can be mentioned.

Monofunctional vinyl ethers include, for example, 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-methyl Cyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydro Furfuryl 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.

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

- Polyfunctional polymerizable compound -
Among other polymerizable compounds, polyfunctional polymerizable compounds include, for example, polyfunctional (meth)acrylates and polyfunctional vinyl ethers.

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, and propylene glycol di(meth)acrylate. , dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate ) 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, 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 addition 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.

Polyfunctional vinyl ethers include, for example, 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, Vinyl ether, 1,4-cyclohexanedimethanol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol Tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexavinyl ether, EO-added trimethylolpropane trivinyl ether, PO-added trimethylolpropane trivinyl ether, EO-added ditrimethylolpropane tetravinyl ether, PO-added ditrimethylolpropane tetravinyl ether, EO-added penta Erythritol tetravinyl ether, PO-added pentaerythritol tetravinyl ether, EO-added dipentaerythritol hexavinyl ether and PO-added dipentaerythritol hexavinyl ether can be mentioned.

<Polymerization initiator>
The primer composition of the present disclosure may contain at least one polymerization initiator. The polymerization initiator is preferably a radical polymerization initiator that generates radicals.

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 Examples include ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

Among them, the polymerization initiator is preferably an acylphosphine compound from the viewpoint of curability by UV-LED (ultraviolet light emitting diode, wavelength 365 nm, 385 nm, or 395 nm).

Acylphosphine oxide compounds include monoacylphosphine oxide compounds and bisacylphosphine oxide compounds, with bisacylphosphine oxide compounds being preferred.

Examples of monoacylphosphine oxide compounds include isobutyryldiphenylphosphine oxide, 2-ethylhexanoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenyl Phosphine oxide, o-toluyldiphenylphosphine oxide, pt-butylbenzoyldiphenylphosphine oxide, 3-pyridylcarbonyldiphenylphosphine oxide, acryloyldiphenylphosphine oxide, benzoyldiphenylphosphine oxide, pivaloylphenylphosphinate vinyl ester, adipoylbis Diphenylphosphine oxide, pivaloyldiphenylphosphine oxide, p-toluyldiphenylphosphine oxide, 4-(t-butyl)benzoyldiphenylphosphine oxide, terephthaloylbisdiphenylphosphine oxide, 2-methylbenzoyldiphenylphosphine oxide, versatoyldiphenylphosphine oxide, 2-methyl-2-ethylhexanoyldiphenylphosphine oxide, 1-methyl-cyclohexanoyldiphenylphosphine oxide, pivaloylphenylphosphinic acid methyl ester and pivaloylphenylphosphinic acid isopropyl ester.

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, 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-dichloro benzoyl)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-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.

The acylphosphine oxide compound may be a polymer, for example, IGM Resins B. V. company's "Omnipol TP".

Among them, the acylphosphine oxide compound is preferably bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (product name "Omnirad 819", manufactured by IGM Resins B.V.).

From the viewpoint of improving the curability of the undercoat composition, the content of the polymerization initiator is preferably 1% by mass or more, more preferably 2% by mass or more, relative to the total amount of the undercoat composition. Although the upper limit of the content of the polymerization initiator is not particularly limited, it is, for example, 10% by mass.

<Polymerization inhibitor>
The primer composition of the present disclosure preferably contains at least one polymerization inhibitor.

Examples of polymerization inhibitors include hydroquinone compounds, phenothiazine, catechols, alkylphenols, alkylbisphenols, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionate, and mercaptobenzimidazole. , phosphites, nitrosamine compounds, hindered amine compounds, and nitroxyl radicals.

Among them, the polymerization inhibitor is more preferably a nitrosamine compound.

Nitrosamine compounds include, for example, N-nitroso-N-phenylhydroxylamine aluminum salt and N-nitroso-N-phenylhydroxylamine. Among them, the nitrosamine compound is preferably N-nitroso-N-phenylhydroxylamine aluminum salt.

From the viewpoint of improving the stability of the undercoat composition over time, the content of the polymerization inhibitor is preferably 0.1% by mass to 1% by mass relative to the total amount of the undercoat composition.

<Additive>
The undercoat composition of the present disclosure may optionally contain additives such as co-sensitizers, UV absorbers, antioxidants, anti-fading agents, conductive salts, solvents, and basic compounds.

<Monofunctional Monomer A1/Polyester Resin>
When the undercoat composition of the present disclosure contains a polyester resin, the mass ratio of the content of the monofunctional monomer A1 to the content of the polyester resin is preferably 5 to 200, more preferably 8 to 100, and 10 to 50. More preferred. When the mass ratio is 5 or more, alkali peelability is improved. On the other hand, when the mass ratio is 200 or less, the adhesion to the substrate is improved.

<Monofunctional Monomer A1 + Monofunctional Monomer A2>
When the undercoat composition of the present disclosure contains a monofunctional monomer A2, the total content of the monofunctional polymerizable monomer A1 and the monofunctional monomer A2 is 60% by mass or more with respect to the total amount of the undercoat composition. is preferred, 70% by mass or more is more preferred, and 80% by mass is even more preferred. Although the upper limit of the total content is not particularly limited, it is, for example, 95% by mass. Adhesiveness with a base material improves that the said total content is 60 mass % or more.

<Monofunctional Monomer A2/Polyester Resin>
When the undercoat composition of the present disclosure contains a polyester resin and a monofunctional monomer A2, the mass ratio of the content of the monofunctional monomer A2 to the content of the polyester resin is preferably 0.5 to 15. ~10 is more preferred, and 1-8 is even more preferred. When the mass ratio is 0.5 or more, alkali peelability is improved. On the other hand, when the mass ratio is 15 or less, the adhesion is improved.

<Physical properties>
The viscosity of the undercoat composition 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 8 mPa. · It is more preferably s to 30 mPa·s. Viscosity is measured at 25° C. using a viscometer, for example, using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

The surface tension of the undercoat composition is preferably 60 mN/m or less, more preferably 20 mN/m to 50 mN/m, even more preferably 20 mN/m to 35 mN/m. The surface tension is measured at 25° C. using a surface tensiometer, for example, by a plate method using an automatic surface tensiometer manufactured by Kyowa Interface Science Co., Ltd. (product name “DY-300”).

[Ink set]
The ink set of the present disclosure includes the undercoat composition of the present disclosure and an active energy ray-curable ink (hereinafter also simply referred to as “ink”) containing a polyfunctional polymerizable monomer.

Each component contained in the active energy ray-curable ink will be described below.

The inks included in the ink set of the present disclosure are active energy ray-curable inks. That is, the ink of the present disclosure is cured by irradiation with active energy rays. The type of active energy rays is not particularly limited, and examples thereof include γ-rays, β-rays, electron beams, ultraviolet rays, and visible rays. Among them, the active energy rays are preferably ultraviolet rays. The inks included in the ink set of the present disclosure are preferably UV curable inks.

<Polyfunctional polymerizable monomer>
The active energy ray-curable ink included in the ink set of the present disclosure contains a polyfunctional polymerizable monomer.

The polyfunctional polymerizable monomer is not particularly limited as long as it has two or more polymerizable groups. From the viewpoint of curability, the polyfunctional monomer is preferably a polyfunctional radically polymerizable monomer, more preferably a polyfunctional ethylenically unsaturated monomer.

Examples of polyfunctional ethylenically unsaturated monomers include polyfunctional (meth)acrylates and polyfunctional vinyl ethers.

Specific examples of polyfunctional (meth)acrylates and polyfunctional vinyl ethers include those described in the undercoat composition section above.

Among them, the polyfunctional polymerizable monomer is preferably a bifunctional polymerizable monomer.

The content of the polyfunctional polymerizable monomer in the ink is preferably 20% by mass or more, more preferably 30% to 70% by mass, based on the total amount of the ink.

<Polymerization initiator>
The ink may contain at least one polymerization initiator. The polymerization initiator is preferably a radical polymerization initiator that generates radicals.

Among them, the polymerization initiator is preferably at least one selected from the group consisting of acylphosphine compounds and thio compounds, and at least one selected from the group consisting of acylphosphine oxide compounds and thioxanthone compounds. A combined use of an acylphosphine oxide compound and a thioxanthone compound is more preferred.

Specific examples of the acylphosphine oxide compound include those described in the undercoat composition section above.

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, 4-butoxycarbonylthioxanthone, 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-ethoxycarbonyl-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-tetramethylbutyl)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-thioxanthon-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride.

The thioxanthone compound may be a commercially available product. Commercially available products include SPEEDCURE series manufactured by Lambson (eg, SPEEDCURE 7010, SPEEDCURE CPTX, SPEEDCURE ITX, etc.).

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

<Polymerization inhibitor>
The ink preferably contains at least one polymerization inhibitor.

Specific examples of the polymerization inhibitor include those described in the undercoat composition section above.

From the viewpoint of improving the stability of the ink over time, the content of the polymerization inhibitor is preferably 0.1% by mass to 1% by mass with respect to the total amount of the ink.

<Colorant>
The ink may contain at least one colorant.
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.

When a pigment is used as the colorant, the pigment can be contained 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 contains at least a pigment, a dispersant and a liquid medium. Details of the dispersant will be described later. Also, the liquid medium may be an organic solvent or a polymerizable monomer.

As the pigment, both commercially available organic pigments and inorganic pigments can be used. As pigments, for example, Seishiro Ito, "Dictionary of Pigments" (published in 2000); Herbst, K.; Hunger "Industrial Organic Pigments", JP-A-2002-12607, JP-A-2002-188025, JP-A-2003-26978 and JP-A-2003-342503.

When the ink contains a colorant, the content of the colorant is preferably 0.5% by mass to 15% by mass, more preferably 1% by mass to 10% by mass, relative to the total amount of the ink. 2% by mass to 5% by mass is more preferable.

<Dispersant>
When a pigment is used as the colorant, the pigment can be contained in the ink as a pigment dispersion. A pigment can be dispersed in a liquid medium using a dispersing agent. As the dispersant, a commonly known one can be used. From the viewpoint of dispersion stability, the dispersant is preferably a compound having both a hydrophilic structure and a hydrophobic structure.

Dispersants include, for example, higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, naphthalene sulfonates, alkyl phosphates, polyoxyalkylene alkyl ether phosphates, polyoxy Low molecular weight dispersants having a molecular weight of less than 1000, such as alkylene alkylphenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene fatty acid amide, and amine oxide.

In addition, examples of dispersants include high molecular weight dispersants having a molecular weight of 1000 or more obtained by copolymerizing a hydrophilic monomer and a hydrophobic monomer. From the viewpoint of dispersion stability, the hydrophilic monomer is preferably a dissociative group-containing monomer, and preferably a dissociative group-containing monomer having a dissociative group and an ethylenically unsaturated bond. Examples of dissociable group-containing monomers include carboxy group-containing monomers, sulfonic acid group-containing monomers, and phosphoric acid group-containing monomers. From the viewpoint of dispersion stability, the hydrophobic monomer is an aromatic group-containing monomer having an aromatic group and an ethylenically unsaturated bond, or an aliphatic hydrocarbon having an aliphatic hydrocarbon group and an ethylenically unsaturated bond. Group-containing monomers are preferred. The polymer may be either a random copolymer or a block copolymer.

Dispersants may be commercially available. Commercially available products include, for example,
DISPERBYK-101 DISPERBYK-102 DISPERBYK-103 DISPERBYK-106 DISPERBYK-110 DISPERBYK-111 DISPERBYK-161 DISPERBYK-162 DISPERBYK-163 DISPERBYK-164 １６８、ＤＩＳＰＥＲＢＹＫ－１７０、ＤＩＳＰＥＲＢＹＫ－１７１、ＤＩＳＰＥＲＢＹＫ－１７４、ＤＩＳＰＥＲＢＹＫ－１８２（以上、ＢＹＫケミー社製）；及びＳＯＬＳＰＥＲＳＥ３０００、ＳＯＬＳＰＥＲＳＥ５０００、ＳＯＬＳＰＥＲＳＥ９０００、ＳＯＬＳＰＥＲＳＥ１２０００、ＳＯＬＳＰＥＲＳＥ１３２４０、ＳＯＬＳＰＥＲＳＥ１３９４０、ＳＯＬＳＰＥＲＳＥ１７０００、ＳＯＬＳＰＥＲＳＥ２２０００、ＳＯＬＳＰＥＲＳＥ２４０００、ＳＯＬＳＰＥＲＳＥ２６０００、ＳＯＬＳＰＥＲＳＥ２８０００、ＳＯＬＳＰＥＲＳＥ３２０００ , SOLSPERSE36000, SOLSPERSE39000, SOLSPERSE41000, SOLSPERSE71000 (manufactured by Lubrizol)
is mentioned.

As a dispersing device for dispersing the pigment, known dispersing devices can be used, for example, ball mills, sand mills, bead mills, roll mills, jet mills, paint shakers, attritors, ultrasonic dispersers and dispersers.

In the ink, the content of the dispersant with respect to the content of the pigment is preferably 0.05 to 1.0, more preferably 0.1 to 0.5 on a mass basis, from the viewpoint of dispersion stability. preferable.

<Other polymerizable compounds>
The ink may contain polymerizable compounds other than the polyfunctional polymerizable monomer. Other polymerizable compounds are preferably monofunctional polymerizable compounds, and preferably monofunctional polymerizable monomers. Examples of monofunctional polymerizable compounds include those described in the section of "Other monofunctional polymerizable compounds" that may be contained in the undercoat composition.

<Additive>
The ink may contain additives such as a co-sensitizer, an ultraviolet absorber, an antioxidant, an anti-fading agent, a conductive salt, a solvent, and a basic compound, if necessary.

<Monofunctional Monomer A1 in Undercoat Composition/Polyfunctional Polymerizable Monomer in Ink>
In the ink set of the present disclosure, the mass ratio of the content of the monofunctional monomer A1 in the undercoat composition to the content of the polyfunctional polymerizable monomer in the ink is 0.00, when the mass of the undercoat composition and the ink are the same. It is preferably 5 to 5, more preferably 1 to 3, even more preferably 1 to 2.5. Adhesiveness with a base material improves that the said mass ratio is 0.5 or more. Odor is reduced as the said mass ratio is 5 or less.

<Multifunctional Polymerizable Monomer in Ink/Monofunctional Monomer A2 in Undercoat Composition>
In the ink set of the present disclosure, the undercoat composition preferably contains a monofunctional monomer A2. The mass ratio of the polyfunctional polymerizable monomer content is preferably 2-25, more preferably 3-20, even more preferably 3-10. Adhesiveness with a base material improves that the said mass ratio is 0.5 or more. When the mass ratio is 25 or less, alkali peelability is improved.

<Polyfunctional Polymerizable Monomer/Polyester Resin in Ink>
In the ink set of the present disclosure, the undercoat composition preferably contains a polyester resin, and when the weight of the undercoat composition and the ink is the same, the polyfunctional polymerizability in the ink with respect to the content of the polyester resin in the undercoat composition The mass ratio of the monomer content is preferably 4-100, more preferably 5-50. When the mass ratio is 4 or more, alkali peelability is improved. Adhesiveness with a base material improves that the said mass ratio is 100 or less.

<Physical properties>
The pH of the ink is preferably 7 to 10, more preferably 7.5 to 9.5, from the viewpoint of improving the ejection stability when applied using an inkjet recording method. The pH is measured at 25° C. using a pH meter, for example, using a pH meter manufactured by DKK Toa (model number “HM-31”).

The viscosity of the ink is preferably 0.5 mPa·s to 30 mPa·s, more preferably 2 mPa·s to 20 mPa·s, preferably 2 mPa·s to 15 mPa·s, and 3 mPa·s. More preferably, it is up to 10 mPa·s. Viscosity is measured at 25° C. using a viscometer, for example, using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

The surface tension of the ink is preferably 60 mN/m or less, more preferably 20 mN/m to 50 mN/m, even more preferably 25 mN/m to 45 mN/m. The surface tension is measured at 25° C. using a surface tensiometer, for example, by a plate method using an automatic surface tensiometer manufactured by Kyowa Interface Science Co., Ltd. (product name “DY-300”).

[Image recording method]
The image recording method of the present disclosure uses the ink set of the present disclosure, comprises the steps of: applying an undercoat composition onto a substrate; irradiating the undercoat composition with a first active energy ray; Applying an ink onto the irradiated undercoat composition; and irradiating the ink with a second actinic energy ray.

(Step of applying undercoat composition)
The image recording method of the present disclosure includes applying a primer composition onto a substrate. Application of the undercoat composition of the present disclosure provides good adhesion between the subsequently applied ink and the substrate.
The type of substrate is not particularly limited, and commonly known substrates can be used as the substrate. Substrates include, for example, glass, quartz, and plastic films. Examples of resins constituting plastic films include cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, acrylic resins, chlorinated polyolefin resins, polyethersulfone resins, polyethylene terephthalate (PET ), polyethylene naphthalate, nylon, polyethylene, polystyrene, polypropylene, polycycloolefin resin, polyimide resin, polycarbonate resin, and polyvinyl acetal. The plastic film may be a film containing only one of these resins, or a film in which two or more of these resins are mixed.

The thickness of the base material is not particularly limited, and is, 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, particularly 10 μm to 90 μm. preferable. When the substrate is glass, the thickness is preferably 0.1 mm to 10 mm, more preferably 0.15 mm to 8 mm, even more preferably 0.2 mm to 5 mm. .

The method of applying the undercoat composition is not particularly limited, and known methods such as a coating method, an inkjet recording method, and an immersion method can be used. Among them, the undercoat composition is preferably applied using an inkjet recording method from the viewpoint of recording a high-definition image.

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. Inkjet recording methods include, for example, a charge control method that uses electrostatic attraction to eject ink, a drop-on-demand method (pressure pulse method) that uses vibration pressure of a piezo element, and an ink that converts an electrical signal into an acoustic beam. Acoustic inkjet method in which ink is ejected using radiation pressure by irradiating to the surface, and thermal inkjet (bubble jet (registered trademark)) method in which ink is heated to form bubbles and the resulting pressure is used. .

As the inkjet head used in the inkjet recording method, a short serial head is used, and the shuttle method performs recording while scanning the head in the width direction of the substrate, and the recording elements are arranged corresponding to the entire side of the substrate. and a line method using a line head that has been developed.

In the line method, patterns can be formed on the entire surface of the base material by scanning the base material in a direction that intersects the direction in which the recording elements are arranged, eliminating the need for a transport system such as a carriage for scanning the short head. In addition, the line method eliminates the need for complicated scanning control of the movement of the carriage and the base material, and only the base material moves.

The droplet volume of the undercoat composition ejected from the inkjet head is preferably 1 pL (picoliter) to 100 pL, more preferably 3 pL to 80 pL, and even more preferably 3 pL to 50 pL.

(Step of irradiating first active energy ray)
The image recording method of the present disclosure includes a step of irradiating the undercoat composition applied in the above step with a first active energy ray.

Examples of the first active energy ray include γ-rays, β-rays, electron beams, ultraviolet rays, and visible rays. Among them, it is preferable that the first active energy ray is an ultraviolet ray.

The peak wavelength of ultraviolet rays is, for example, preferably 200 nm to 405 nm, more preferably 250 nm to 400 nm, even more preferably 300 nm to 400 nm.

Mercury lamps, gas lasers, and solid-state lasers are mainly used as light sources for ultraviolet irradiation, and mercury lamps, metal halide lamps, and ultraviolet fluorescent lamps are widely known. UV-LEDs (ultraviolet light emitting diodes) and UV-LDs (ultraviolet laser diodes) are small, have a long life, are highly efficient, and are low in cost, and are expected to serve as light sources for ultraviolet irradiation. Among them, the light source for ultraviolet irradiation is preferably a metal halide lamp, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, or a UV-LED.

In the present disclosure, polymerizing only a part of the polymerizable monomer in the undercoat composition or ink is also referred to as "temporary curing", and irradiation with active energy rays for temporary curing is also referred to as "pinning exposure".
In the present disclosure, polymerizing substantially all of the polymerizable monomers in the undercoat composition or ink is also referred to as "main curing", and irradiation with active energy rays for final curing is also referred to as "main exposure".

In the step of irradiating the first active energy ray, it is preferable to temporarily cure the undercoat composition. Specifically, it is preferable to subject the undercoat composition to pinning exposure.

The reaction rate of the undercoat composition after pinning exposure is preferably 10% to 80%.

Here, the reaction rate of the undercoat composition means the polymerization rate of the polymerizable monomer contained in the undercoat composition determined by high performance liquid chromatography.

When the reaction rate of the undercoat composition is 10% or more, insufficient dot spread is suppressed, and as a result, the graininess of the finally obtained image is improved.

In addition, since the reaction rate of the undercoat composition is 80% or less, interference between droplets of the undercoat composition is suppressed, and as a result, the image quality of the finally obtained image is improved.

The reaction rate of the undercoat composition is preferably 15% or more from the viewpoint of further improving the graininess of the finally obtained image.

The reaction rate of the undercoat composition is preferably 75% or less, more preferably 50% or less, and preferably 40% or less, from the viewpoint of further improving the image quality of the finally obtained image. , is more preferably 30% or less, and even more preferably 25% or less.

The reactivity of the undercoat composition is determined by the following method.
A substrate is prepared which has undergone operations up to completion of irradiation of the active energy ray to the undercoat composition. A sample piece having a size of 20 mm×50 mm (hereinafter referred to as a post-irradiation sample piece) is cut from the region of the base material where the undercoat film is present. The cut sample piece after irradiation is immersed in 10 mL of THF (tetrahydrofuran) for 24 hours to obtain an eluate in which the undercoat composition is eluted. The obtained eluate is subjected to high performance liquid chromatography to determine the amount of the polymerizable monomer (hereinafter referred to as "post-irradiation monomer amount X1").
Separately, the same operation as above is performed except that the undercoat composition on the substrate is not irradiated with an active energy ray, and the amount of the polymerizable monomer (hereinafter referred to as "non-irradiated monomer amount X1") is determined. .
Based on the post-irradiation monomer amount X1 and the non-irradiated monomer amount X1, the reaction rate (%) of the undercoat composition is obtained from the following formula.
Reaction rate (%) of the undercoat composition = ((monomer amount X1 when unirradiated-monomer amount X1 after irradiation)/monomer amount when unirradiated X1) x 100

The exposure amount of the active energy ray for pinning exposure is preferably 10 mJ/cm ² to 100 mJ/cm ² , more preferably 20 mJ/cm ² to 60 mJ, from the viewpoint of easily achieving the reaction rate of the undercoat composition described above. /cm ² is more preferred.

(Step of applying ink)
The image recording method of the present disclosure includes a step of applying ink onto the undercoat composition irradiated with the first active energy ray in the above step.

The method of applying the ink is not particularly limited, and known methods such as a coating method, an inkjet recording method, and an immersion method can be used. Among them, the ink is preferably applied using an inkjet recording method from the viewpoint of recording a high-definition image.

The details of the inkjet recording method are as described above.

The droplet volume of ink ejected from the inkjet head is preferably 1 pL (picoliter) to 100 pL, more preferably 3 pL to 80 pL, and even more preferably 3 pL to 50 pL.

(Step of irradiating ink with second active energy ray)
The image recording method of the present disclosure includes a step of irradiating the ink applied in the above step with a second active energy ray.

Examples of the second active energy ray include γ-rays, β-rays, electron beams, ultraviolet rays, and visible rays. Among them, it is preferable that the second active energy ray is an ultraviolet ray.

The light source for ultraviolet irradiation is preferably a metal halide lamp, high-pressure mercury lamp, medium-pressure mercury lamp, low-pressure mercury lamp, or UV-LED.

In the step of irradiating the second active energy ray, it is preferable to temporarily cure the ink. Specifically, it is preferable to perform pinning exposure on the ink.

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

Here, the reaction rate of the ink means the polymerization rate of the polymerizable monomer contained in the ink determined by high performance liquid chromatography.

The ink reaction rate of 10% or more suppresses insufficient spread of dots, and as a result, the graininess of the finally obtained image is improved.

In addition, since the ink reaction rate is 80% or less, interference between ink dots is suppressed, and as a result, the image quality of the finally obtained image is improved.

The ink reaction rate is preferably 15% or more from the viewpoint of further improving the graininess of the finally obtained image.

The ink reaction rate is preferably 75% or less, more preferably 50% or less, more preferably 40% or less, and 30% or less, from the viewpoint of further improving the image quality of the finally obtained image. % or less, more preferably 25% or less.

In the image recording method of the present disclosure, it is preferable to perform full curing after temporarily curing the ink. That is, it is preferable to perform the main exposure after performing the pinning exposure on the ink.
The reaction rate of the ink after the main exposure is preferably more than 80% and 100% or less, more preferably 85% to 100%, even more preferably 90% to 100%.
When the reaction rate is over 80%, the adhesion is further improved.

The exposure amount of the second active energy ray for pinning exposure is preferably 10 mJ/cm ² to 100 mJ/cm ² , more preferably 20 mJ/cm ² to 60 mJ, from the viewpoint of achieving the above-mentioned ink reactivity more easily. /cm ² is more preferred.

The exposure amount of the active energy ray for the main exposure is preferably 50 mJ/cm ² to 1000 mJ/cm ² and more preferably 200 mJ/cm ² to 800 mJ/cm ² from the viewpoint of completely curing the ink. more preferred.

In the main exposure, from the viewpoint of improving the adhesion to the substrate, it is preferable to irradiate the active energy ray in an atmosphere with an oxygen concentration of less than 1% by volume. The oxygen concentration is more preferably 0.5% by volume or less, and even more preferably 0.3% by volume or less.

Hereinafter, the present disclosure will be described more specifically with reference to examples, but the present disclosure is not limited to the following examples as long as it does not exceed the gist thereof.

<Examples 1 to 35, Comparative Examples 1 to 4>
[Preparation of Inks 1 to 5]
First, a black pigment dispersion was prepared.

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 "SOLSPERSE32000" manufactured by Lubrizol), and cyclic trimethylolpropane formal as a dispersion medium Acrylate (product name “Viscoat #200”, manufactured by Osaka Organic Chemical Industry) and 75 parts by mass were charged into a dispersing machine Motor Mill M50 (manufactured by Eiger), and zirconia beads with a diameter of 0.65 mm were used at a peripheral speed of 9 m / s for 4 hours to obtain a black pigment dispersion.

Next, the prepared pigment dispersion, the polymerizable monomers (monofunctional monomers and polyfunctional monomers) listed in Table 3 below, the polyester resin, the polymerization initiator, the polymerization inhibitor, and the surfactant, each component is 3 were mixed so as to achieve the content (% by mass) described in 3. The mixture was stirred for 20 minutes at 25° C. and 5000 rpm using a mixer (product name “L4R”, manufactured by Silverson) to obtain an ink.

[Preparation of undercoat composition]
Polymerizable monomers listed in Tables 4 to 8 below (monofunctional monomer A1, monofunctional monomer A2, and other polymerizable monomers), polymerization initiators, polymerization inhibitors, and surfactants, each component in Table 4 It was mixed so that the contents (% by mass) shown in Table 8 were obtained. The mixture was stirred for 20 minutes at 25° C. and 5000 rpm using a mixer (product name “L4R”, manufactured by Silverson) to obtain an undercoat composition.

The details of each component listed in Tables 3 to 8 are as follows.

<Polymerizable Monomer>
・CTFA: cyclic trimethylolpropane formal acrylate (product name “Viscoat #200”, manufactured by Osaka Organic Chemical Industry Co., Ltd.)
・CHDOL-10: 1,4-dioxaspiro[4,5]dec-2-ylmethyl acrylate (product name “CHDOL-10”, manufactured by Osaka Organic Chemical Industry Co., Ltd.)
・ MEDOL-10: (2-methyl-2-ethyl-1,3-dioxolan-4-yl) methyl acrylate (product name “MEDOL-10”, manufactured by Osaka Organic Chemical Industry Co., Ltd.)
・ SR789: dicyclopentanyl methyl acrylate (product name “SR789”, manufactured by Sartomer)
・THFA: Tetrahydrofurfuryl acrylate (product name “SR285”, manufactured by Sartomer)
・ ACMO: acryloyl morpholine (product name “acryloyl morpholine”, manufactured by KJ Chemical Co., Ltd.)
・ A-SA: 2-acryloyloxyethyl succinic acid (product name “NK Ester A-SA”, manufactured by Shin-Nakamura Chemical Co., Ltd.)
・ 3MPDDA: 3-methyl-1,5-pentanediol diacrylate (product name “SR341”, manufactured by Sartomer)
・IBOA: isobornyl acrylate (product name “SR506”, manufactured by Sartomer)

<Polyester resin>
・FC1588: manufactured by Mitsubishi Chemical ・TP219: manufactured by Mitsubishi Chemical ・UVAD081: manufactured by Osaka Soda ・GK250: manufactured by Toyobo ・TP-217: manufactured by Mitsubishi Chemical ・TP-220: manufactured by Mitsubishi Chemical ・TP-290: Manufactured by Mitsubishi Chemical Corporation

<Polymerization initiator>
- Omnirad 819: bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (manufactured by IGM Resins B.V.)
・Speedcure 7010: 1,3-di({α-[1-chloro-9-oxo-9H-thioxanthen-4-yl)oxy]acetylpoly[oxy(1-methylethylene)]}oxy)-2,2 - bis({α-[1-methylethylene)]}oxymethyl)propane

<Polymerization inhibitor>
・ Q-1301: N-nitroso-N-phenylhydroxylamine aluminum salt (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.)

<Colorant>
・ Black pigment: Special Black 250 (manufactured by Orion Engineered Carbons)

<Dispersant>
・SOLSPERSE32000: polyethyleneimine-based dispersant (manufactured by Lubrizol)

<Surfactant>
・ Tegorad 2010: (meth) acroyl group-containing silicone surfactant (manufactured by Evonik)

[Image recording]
Using an inkjet recording device (product name “CylinderJET”, manufactured by Tritec) and an inkjet head (product name “KJ4A-RH”, manufactured by Kyocera), the body of a PET bottle (product name “PET500 Maru”, manufactured by Kokugo) The prepared basecoat composition was applied on the part. Specifically, a droplet volume of 11 pL (picoliters) and a resolution of 600×600 dpi (dots per inch) were placed on the surface of the PET bottle with a size of 7 cm in the longitudinal direction and 5 cm in the circumferential direction of the PET bottle. A 100% solid image having a thickness of 4 μm was recorded. Further, an ink was applied onto the undercoat composition under the same conditions as those for applying the undercoat composition, and a 100% solid image with a thickness of 4 μm was recorded. After applying the undercoat composition and after applying the ink, ultraviolet rays were irradiated at an exposure amount of 40 mJ/cm ² using an LED light source attached to the inkjet recording apparatus. As an LED light source, a UV-LED irradiator with a peak wavelength of 385 nm (product name “G4B”, manufactured by Kyocera Corporation) was used. After that, the PET bottle on which the image was recorded was put into the exposure machine. The PET bottle was set horizontally. The exposure machine can rotate the PET bottle along the circumferential direction around the longitudinal axis. The entire image recorded on the PET bottle was rotated and exposed using an 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 the oxygen concentration in the exposure machine was adjusted to 1% by volume or less. , was flowed with nitrogen. An LED light source was used to irradiate ultraviolet rays at an exposure amount of 500 mJ/cm ² to completely cure the undercoat composition and the ink to obtain an image recorded matter.
"Complete curing" means that plain paper (for example, copy paper C2 manufactured by Fuji Xerox Co., Ltd., product code "V436") is applied with a uniform force (500 mN/cm ² to 1,000 mN/cm ² ). It can be judged whether the image is transferred to plain paper by pressing against the image. In other words, a state in which no transfer is made at all is referred to as a completely cured state.

[evaluation]
Adhesion, odor, and alkali peelability were evaluated for each of Examples and Comparative Examples using the obtained image recorded matter. The evaluation method is as follows.

<Adhesion>
A tape adhesion test was performed using the resulting image record in accordance with JISK5600-5-6:1999. After the test, the recorded image was visually observed. The percentage of the area where the ink film was peeled off (peeled area ratio) (%) was calculated with respect to the entire evaluation area.
Adhesion was evaluated based on the peeled area ratio. It can be said that the smaller the peeled area ratio, the better the adhesion. Evaluation criteria are as follows.
5: No peeling of the ink film occurred.
4: The peeled area ratio was more than 0% and 10% or less.
3: The peeled area ratio was more than 10% and 20% or less.
2: The peeled area ratio was more than 20% and 50% or less.
1: The peeled area ratio was over 50%.

<Odor>
The recorded image was placed in a 240 mm×340 mm zipped aluminum vinyl bag (manufactured by Esco) and left at 30°C. After 1 hour, 24 hours and 1 week, the plastic bag was opened and the odor was determined. Evaluation criteria are as follows.
5: No odor after 1 hour, 24 hours and 1 week.
4: No odor after 1 hour and 24 hours, but odor after 1 week.
3: No odor after 1 hour, but odor after 24 hours and 1 week.
2: There was no odor immediately after image recording, but there was an odor after one hour.
1: There was an odor immediately after image recording.

<Alkali Peelability>
The obtained image recorded matter was immersed in a 1.5% by mass sodium hydroxide aqueous solution at 85° C., and the state of peeling was visually observed. The peeling time was defined as the time from when the image-recorded material was immersed until the ink film was completely peeled off from the image-recorded material.
The alkali peelability was evaluated based on the peeling time. It can be said that the shorter the peeling time, the better the alkali peelability. Evaluation criteria are as follows.
5: The peeling time was within 5 minutes.
4: The peeling time was more than 5 minutes and within 10 minutes.
3: The peeling time was more than 10 minutes and within 15 minutes.
2: The peeling time was more than 15 minutes and within 30 minutes.
1: The peeling time was longer than 30 minutes.

Tables 4 to 8 show the evaluation results.

In Tables 4 to 8, for the undercoat composition, the content (% by mass) of each component in the undercoat composition is described. Regarding the ink, the type of ink was described (see Table 3).
Regarding the polymerizable monomer, the SP value (the unit "MPa ^1/2 " is omitted in the table) and the glass transition temperature Tg (the unit "°C" is omitted in the table) are described.
Regarding the polyester resin, the glass transition temperature Tg, acid value (the unit "mgKOH/g" is omitted in the table), hydroxyl value (the unit "mgKOH/g" is omitted in the table), and weight average molecular weight Mw are described. did.
"Polymerizable monomer A2 in the undercoat composition/polyester resin in the undercoat composition" means the mass ratio of the content of the polymerizable monomer A2 in the undercoat composition to the content of the polyester resin in the undercoat composition. do.
"Monofunctional monomer A1 in the undercoat composition/polyfunctional monomer in the ink" means the mass ratio of the content of the monofunctional monomer A1 in the undercoat composition to the content of the polyfunctional monomer in the ink.
"Multifunctional polymerizable monomer in the ink/monofunctional polymerizable monomer A2 in the undercoat composition" is the content of the polyfunctional polymerizable monomer in the ink relative to the content of the monofunctional polymerizable monomer A2 in the undercoat composition. means mass ratio of quantity.
"Polyfunctional polymerizable monomer in ink/polyester resin in undercoat composition" means the mass ratio of the content of the polyfunctional polymerizable monomer in the ink to the content of the polyester resin in the undercoat composition.

As shown in Tables 4 to 8, in Examples 1 to 33, the SP values are 17.5 MPa ^1/2 to 23.0 MPa ^1/2 , and consist of a cyclic ether structure and an alicyclic structure. It contains a monofunctional polymerizable monomer A1 containing at least one structure selected from the group, the content of the monofunctional polymerizable monomer A1 is 45% by mass or more with respect to the total amount of the undercoat composition, Since it does not contain a functional polymerizable compound, or the content of the polyfunctional polymerizable compound is 25% by mass or less with respect to the total amount of the undercoat composition, it was found that the adhesion to the substrate is excellent. .

On the other hand, in Comparative Examples 1 and 4, since the undercoat composition did not contain the monofunctional monomer A1, it was found that the adhesion to the substrate was poor.

In Comparative Example 2, the content of the monofunctional monomer A1 in the undercoat composition was less than 45% by mass, so it was found that the adhesion to the substrate was poor.

In Comparative Example 3, the content of the polyfunctional polymerizable compound in the undercoat composition was more than 25% by mass, so it was found that the adhesion to the substrate was poor.

In Example 3, since the glass transition temperature of the monofunctional monomer A1 in the undercoat composition was -10°C or higher, it was found to be superior to Example 5 in adhesion to the substrate.
In Example 4, the monofunctional monomer A1 in the undercoat composition has a glass transition temperature of 40° C. or less, so that the adhesiveness to the substrate is excellent and the odor is reduced as compared with Example 6. I found out.

It was found that in Example 1, the odor was reduced compared to Example 4 because the monofunctional monomer A1 in the undercoat composition contained a cyclic ether structure.

In Example 8, since the undercoat composition contained a polyester resin, it was found to be superior to Example 1 in adhesion to the substrate and alkali releasability.

In Example 8, since the acid value of the polyester resin in the undercoat composition was 3 mgKOH/g or more, it was found to be superior to Example 9 in alkali releasability.
In Example 8, since the acid value of the polyester resin in the undercoat composition was 14 mgKOH/g or less, it was found to be superior to Example 10 in adhesion to the substrate.

In Examples 8-10, since the hydroxyl value of the polyester resin in the undercoat composition is 20 mgKOH / g or more, compared to Examples 11-14, adhesion to the substrate, or alkali peelability I found it to be excellent.

In Examples 8-11, the weight-average molecular weight of the polyester resin in the undercoat composition was 10,000 or less.

In Example 12, since the polyester resin in the undercoat composition had a glass transition temperature of 30° C. or higher, it was found to be superior to Example 14 in adhesion to the substrate.
In Example 12, since the polyester resin in the undercoat composition had a glass transition temperature of 65° C. or less, it was found to be superior to Example 13 in adhesion to the substrate.

In Example 32, the mass ratio of the content of the monofunctional monomer A1 to the content of the polyester resin was 8 or more.
In Example 31, the mass ratio of the content of the monofunctional monomer A1 to the content of the polyester resin was 100 or less.

In Example 15, since the undercoat composition contained the monofunctional monomer A2, it was found to be superior to Example 1 in alkali removability.

In Example 16, since the undercoat composition contained the polyester resin and the monofunctional monomer A2, it was found to be superior to Example 15 in adhesion to the substrate and alkali releasability.

In Example 19, the total content of monofunctional monomer A1 and monofunctional monomer A2 in the undercoat composition is 60% by mass or more. Do you get it.

In Example 18, the mass ratio of the content of the monofunctional monomer A2 to the content of the polyester resin was 1 or more.
In Example 18, the mass ratio of the content of the monofunctional monomer A2 to the content of the polyester resin was 10 or less.

In Example 24, the mass ratio of the content of the monofunctional monomer A1 in the undercoat composition to the content of the polyfunctional polymerizable monomer in the ink is 1 or more. It turned out that it is excellent in adhesiveness with.
In Example 23, the mass ratio of the content of the monofunctional monomer A1 in the undercoat composition to the content of the polyfunctional polymerizable monomer in the ink was 3 or less. It was found to be excellent in durability and to reduce odor.

In Example 29, the mass ratio of the content of the polyfunctional polymerizable monomer in the ink to the content of the monofunctional polymerizable monomer A2 in the undercoat composition was 1 or more. It was found that the odor was reduced.
In Example 27, the mass ratio of the content of the polyfunctional polymerizable monomer in the ink to the content of the monofunctional polymerizable monomer A2 in the undercoat composition was 20 or less. It was found to be excellent in alkali peelability.

In Example 32, the mass ratio of the content of the polyfunctional polymerizable monomer in the ink to the content of the polyester resin in the undercoat composition was 5 or more. I found it to be excellent.
In Example 31, the mass ratio of the content of the polyfunctional polymerizable monomer in the ink to the content of the polyester resin in the undercoat composition was 50 or less. It turned out that it is excellent in adhesiveness.

The disclosure of Japanese Patent Application No. 2021-073512 filed on April 23, 2021 is incorporated herein by reference in its entirety. In addition, all publications, patent applications and technical standards mentioned herein are to the same extent as if each individual publication, patent application and technical standard were specifically and individually noted to be incorporated by reference. , incorporated herein by reference.

Claims

A monofunctional polymerizable monomer A1 having an SP value of 17.5 MPa 1/2 to 23.0 MPa 1/2 and containing at least one structure selected from the group consisting of a cyclic ether structure and an alicyclic structure. contains,
The content of the monofunctional polymerizable monomer A1 is 45% by mass or more with respect to the total amount of the active energy ray-curable undercoat composition,
An active energy ray-curable undercoat composition that does not contain a polyfunctional polymerizable compound or that has a polyfunctional polymerizable compound content of more than 0% by mass and 25% by mass or less with respect to the total amount of the undercoat composition. .
The active energy ray-curable undercoat composition according to claim 1, wherein the monofunctional polymerizable monomer A1 has a glass transition temperature of -10°C to 40°C when converted into a homopolymer.
The active energy ray-curable undercoat composition according to claim 1 or 2, wherein the monofunctional polymerizable monomer A1 contains a cyclic ether structure.
The active energy ray-curable undercoat composition according to any one of claims 1 to 3, further comprising a polyester resin.
The active energy ray-curable undercoat composition according to claim 4, wherein the polyester resin has an acid value of 3 mgKOH/g to 14 mgKOH/g.
The active energy ray-curable undercoat composition according to claim 4 or 5, wherein the polyester resin has a hydroxyl value of 20 mgKOH/g or more.
The active energy ray-curable undercoat composition according to any one of claims 4 to 6, wherein the polyester resin has a weight average molecular weight of 10,000 or less.
The active energy ray-curable undercoat composition according to any one of claims 4 to 7, wherein the polyester resin has a glass transition temperature of 30°C to 65°C.
The active energy ray-curable undercoat composition according to any one of claims 4 to 8, wherein the mass ratio of the content of the monofunctional polymerizable monomer A1 to the content of the polyester resin is 8 to 100. thing.
The active energy ray-curable undercoat composition according to any one of claims 1 to 9, further comprising a monofunctional polymerizable monomer A2 having an acid group.
The active energy ray-curable undercoat composition according to any one of claims 4 to 9, further comprising the polyester resin and a monofunctional polymerizable monomer A2 having an acid group.
The total content of the monofunctional polymerizable monomer A1 and the monofunctional polymerizable monomer A2 having an acid group is 60% by mass or more with respect to the total amount of the active energy ray-curable undercoat composition, or The active energy ray-curable undercoat composition according to claim 11.
The active energy ray-curable undercoat composition according to claim 11, wherein the mass ratio of the content of the monofunctional polymerizable monomer A2 having an acid group to the content of the polyester resin is 1-10.
The active energy ray-curable undercoat composition according to any one of claims 1 to 13,
an active energy ray-curable ink containing a polyfunctional polymerizable monomer;
Ink set with
When the active energy ray-curable undercoat composition and the active energy ray-curable ink have the same mass,
The mass ratio of the content of the monofunctional polymerizable monomer A1 in the active energy ray-curable undercoat composition to the content of the multifunctional polymerizable monomer in the active energy ray-curable ink is 1 to 3. The ink set according to claim 14.
Equipped with the active energy ray-curable undercoat composition according to any one of claims 10 to 13,
When the active energy ray-curable undercoat composition and the active energy ray-curable ink have the same mass,
The mass ratio of the content of the polyfunctional polymerizable monomer in the active energy ray-curable ink to the content of the monofunctional polymerizable monomer A2 in the active energy ray-curable undercoat composition is 1 to 20. The ink set according to claim 14 or 15.
Equipped with the active energy ray-curable undercoat composition according to any one of claims 4 to 9, claim 11, or claim 13,
When the active energy ray-curable undercoat composition and the active energy ray-curable ink have the same mass,
The mass ratio of the content of the polyfunctional polymerizable monomer in the active energy ray-curable ink to the content of the polyester resin in the active energy ray-curable undercoat composition is 5 to 50, or The ink set according to claim 15.
The ink set according to any one of claims 14 to 17 is used,
A step of applying the active energy ray-curable undercoat composition onto a substrate by an inkjet recording method;
a step of irradiating the active energy ray-curable undercoat composition with a first active energy ray;
a step of applying the active energy ray-curable ink by an inkjet recording method onto the active energy ray-curable undercoat composition irradiated with the first active energy ray;
and a step of irradiating the actinic energy ray-curable ink with a second actinic energy ray.