JP2012144582A - Ink composition, image forming method, and printed matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an ink composition that can strike a balance between curability of an image portion and flexibility thereof to a moderate level and can prevent cracks from occurring in the image portion even if a large stress is applied; an image forming method using the ink composition; and a printed matter.SOLUTION: The ink composition comprises: a polymer (A) having, on a side chain, a polymerizable group and at least one group selected from a fluorine-substituted hydrocarbon group (a1), a group (a2) having a siloxane structure, and a long-chain alkyl group (a3); silica particles (B) each having the polymerizable group; a polymerizable compound (C) other than (A) and (B); and a polymerization initiator (D). The silica particles (B) accounts for 0.1-30 mass% of the total content (TX) of the polymer (A), the silica particles (B) and the polymerizable compound (C).

Description

  The present invention relates to an ink composition, an image forming method using the ink composition, and a printed matter obtained by the image forming method.

  As an image recording method for forming an image on a recording medium such as paper based on an image data signal, there are an electrophotographic method, a sublimation type, a melt type thermal transfer method, an ink jet method and the like. For example, the ink jet method can be implemented with an inexpensive apparatus, and the ink can be used efficiently and the running cost can be achieved because the image is directly formed on the recording medium by ejecting the ink only to the required image portion. Is cheap. Furthermore, there is little noise and it is excellent as an image recording method.

According to the inkjet method, printing is possible not only on plain paper but also on non-water-absorbing recording media such as plastic sheets and metal plates, but speeding up and high image quality when printing are important issues. The time required for drying and curing of the droplets after printing has a property that greatly affects the productivity of the printed matter and the sharpness of the printed image.
As one of the ink jet methods, there is a recording method using an ink for ink jet recording that can be cured by irradiation of radiation. According to this method, the productivity of printing can be improved and a sharp image can be formed by irradiating the ink immediately after ink ejection or after a certain time and curing the ink droplets.

  As an example of an ink composition that can be cured by irradiation with radiation, Patent Document 1 includes a partial structure selected from a fluorine-substituted hydrocarbon group, a siloxane skeleton, and a long-chain alkyl group and a radical polymerizable group in the side chain. An ink composition having improved curability, ejection stability, and blocking resistance by including a polymer and a specific sensitizing dye is disclosed.

  In Patent Document 2, as a technique for improving the hardness, scratch resistance, low curling property, adhesion, transparency and the like of a cured film in a resin composition for forming a film on the surface of a substrate, silicon or the like It is disclosed to use particles in which an organic compound having a polymerizable unsaturated group and a specific group is bonded to the oxide particles.

JP 2010-18728 A JP 2000-230107 A

  However, in each of the above-mentioned technologies, not only has been studied not only to increase the hardness of the cured film to the ink composition, but also to impart appropriate flexibility to enhance the processability of the printed material. That is, in each of the above-described technologies, there is no study of suppressing cracks in the image portion when cutting the formed image to a desired size or when some stress is applied, such as punching processing. There was a need for further improvements.

  The present invention has been made in view of the above, and an ink composition capable of achieving both hardness and flexibility of an image area in an appropriate range and suppressing cracks in an image area even when stress is applied. And an image forming method using the same, and a printed matter.

Specific means for achieving the above object are as follows.
<1> (A) at least one group selected from a polymerizable group on the side chain, and (a1) a fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long-chain alkyl group A polymer having
(B) silica fine particles having a polymerizable group;
(C) The polymerizable compound other than (A) and (B),
(D) a polymerization initiator;
Including
0.1 mass%-30 mass% of said (B) silica fine particles are included with respect to the total content (TX) of said (A) polymer, said (B) silica fine particles, and said (C) polymeric compound. Ink composition characterized by the above.

  <2> The ink composition according to <1>, wherein the polymerizable group of the polymer (A) is a (meth) acrylic acid ester group.

  <3> The ink composition according to <1> or <2>, wherein the polymerizable group of the (B) silica fine particles is a (meth) acrylate group.

  <4> The polymer according to any one of <1> to <3>, wherein the polymer (A) is included in an amount of 0.2% by mass to 10% by mass with respect to the total content (TX). Ink composition.

  <5> The ink composition according to any one of <1> to <4>, wherein the content of the monofunctional monomer in the polymerizable compound (C) is 60% by mass to 100% by mass. It is a thing.

  <6> The ink composition according to any one of <1> to <5>, wherein the polymer (A) includes a urethane structure or a urea structure as a main chain structure.

  <7> The ink composition according to any one of <1> to <5>, wherein the polymer (A) includes a (meth) acrylate structure as a main chain structure.

  <8> (E) The ink composition according to any one of <1> to <7>, further including a colorant.

  <9> The ink composition according to any one of <1> to <8>, which is for inkjet recording.

<10> An image forming method comprising an ink application step of applying the ink composition according to any one of <1> to <9> onto a recording medium by an inkjet method.

<11> A printed matter obtained by the image forming method according to <10>.

  According to the present invention, it is possible to achieve both the hardness and flexibility of the image area within an appropriate range, and an ink composition capable of suppressing cracks in the image area even when a large stress such as drilling is applied, And an image forming method using the same, and a printed matter.

[Ink composition]
The ink composition of the present invention is selected from (A) a side chain, a polymerizable group, and (a1) a fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long-chain alkyl group. A polymer having at least one group, (B) a silica fine particle having a polymerizable group, (C) a polymerizable compound other than (A) and (B), and (D) a polymerization initiator, The (B) silica fine particles are 0.1% by mass to 30% with respect to the total content (TX) of the (A) polymer, the (B) silica fine particles, and the (C) polymerizable compound. It is characterized by containing mass%.
Hereinafter, the essential components constituting the ink composition of the present invention will be described. In this specification, when referring to “acrylate” and / or “methacrylate”, it refers to “(meth) acrylate” and “acryl” and / or “methacryl”. May be described respectively.

<(A) The side chain has a polymerizable group, and (a1) a fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long chain alkyl group. Polymer>
The ink composition of the present invention is selected from (A) a side chain, a polymerizable group, and (a1) a fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long-chain alkyl group. A polymer having at least one group (hereinafter, also referred to as “surface segregation polymer” as appropriate). First, the polymer has (a1) a fluorine-substituted hydrocarbon group and (a2) a siloxane structure. The group to be included and (a3) the long-chain alkyl group are each described.

((A1) Fluorine-substituted hydrocarbon group)
The fluorine-substituted hydrocarbon group in the surface segregation polymer in the present invention may be a hydrocarbon group substituted with at least one fluorine atom, for example, a fluoroalkyl in which at least one hydrogen atom in the alkyl group is substituted with a fluorine atom And a perfluoroalkyl group in which all hydrogen atoms of the alkyl group are substituted with fluorine is more preferable.

  As an alkyl group, C3-C12 is preferable, C4-C10 is more preferable, and C6-C8 is still more preferable.

Specific embodiments of the fluorine-substituted hydrocarbon group in the present invention will be described.
Preferred fluorine-substituted hydrocarbon groups that the surface segregation polymer has in the side chain include those represented by the following general formula I.

In the above (general formula I), n represents an integer of 0 or more, and Y ¹ is any ^one group selected from the following Y ¹ group. Moreover, * represents the position connected with the side chain of a polymer.

  Among the groups represented by the above (General Formula I), those in which “n” in (General Formula I) is 0 to 20 are preferable, 0 to 7 are more preferable, and 3 or 5 are preferable. Particularly preferred.

The method for introducing the structure of the general formula I into the side chain of the polymer (A) is not particularly limited. For example, a monomer having the structure of the general formula (I) is appropriately selected during the synthesis of the polymer (A). When applied, the structure of (general formula I) can be introduced into the repeating unit of the obtained polymer.
As the monomer having the structure of (general formula I), a commercially available compound can be used, but the desired structure contained in (general formula I) is compared with a commercially available monomer having no structure of (general formula I). You may introduce and use suitably. There is no limitation on the method of introducing the structure of (general formula I) into a commercially available monomer, and a known method may be applied as appropriate.

  The monomer having the structure of the general formula I can be appropriately selected according to the desired main chain structure of the polymer (A). For example, if the polymer has a (meth) acrylic structure in the main chain, the following general formula It is preferable to use a monomer represented by (I-2).

In the above (general formula I-2), R ¹ represents a hydrogen atom, a methyl group, an ethyl group, or a halogen atom, R ² and R ³ each represent a hydrogen atom or an alkyl group, and X represents a divalent linkage. Represents a group. Y ¹ and n are synonymous with the above-mentioned (general formula I) including the preferred range, and m represents an integer of 0 or more.
When m is 2 or more, functional groups on adjacent carbons (that is, R ² and R ³ bonded to adjacent carbons) may be bonded to form an aliphatic ring. .

In (General Formula I-2), R ¹ is a hydrogen atom, a methyl group, an ethyl group, or a halogen atom, more preferably a hydrogen atom or a methyl group, and still more preferably a methyl group.

In the general formula I-2, the alkyl group represented by R ² and R ³ is preferably an alkyl group having 1 to 4 carbon atoms, and may be a linear structure or a branched structure. Good. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, and the like, preferably a hydrogen atom or a methyl group, more preferably hydrogen. Is an atom.

Examples of the divalent linking group as X include —O—, —S—, —N (R ⁴ ) —, and the like. Among these, -O- is more preferable.
Here, R ⁴ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group may be a linear structure or a branched structure, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Preferably, they are a hydrogen atom and a methyl group.

  Moreover, as m, the integer of 0-8 is preferable, it is more preferable that it is 2-8, and it is especially preferable that it is 2-6.

  By using the monomer represented by the general formula (I-2), a polymer (A) having a repeating unit represented by the following general formula (U-a1-1) can be obtained. The (A) polymer preferably has one repeating unit represented by the general formula (U-a1-1).

In the general formula (U-a1-1), Y ¹ and n are synonymous with the above-mentioned (general formula I) including the preferred range, and R ¹ , R ² , R ³ , X, and m are The above (General Formula I-2) is synonymous with the preferable range.

  Specific examples of the monomer represented by the above (General Formula I-2) that can be used in the present invention are shown below.

  When the polymer (A) is a so-called polyurethane resin or polyurea resin containing a urethane bond (—NHCOO— or —OCONH—) or a urea bond (—NHCONH—) in the main chain structure, As the diol component or diamine component, it is preferable to use a monomer represented by the following general formula (I-3). That is, when the polymer (A) has a urethane bond, the compound of general formula (I-3) is used as a diol component, and when it has a urea bond, the compound of general formula (I-3) is converted to a diamine component. May be used.

In the above (General Formula I-3), Z ¹³ represents a hydroxyl group or an amino group (—NH ₂ ), and W ¹³ represents a residue obtained by removing three hydrogen atoms from a saturated hydrocarbon. Moreover, n and Y ¹ are synonymous also including the above-mentioned (general formula I) and a preferable range.

In (General Formula I-3), W ¹³ represents a residue obtained by removing three hydrogen atoms from a saturated hydrocarbon. The saturated hydrocarbon preferably has 3 to 30 carbon atoms, and may be linear, branched or cyclic. As for carbon number, it is more preferable that it is 3-25, and it is still more preferable that it is 3-10.
Specific examples include a residue obtained by removing three hydrogen atoms from a compound such as propane, 2-methylpropane, butane, pentane, and cyclohexane. In the saturated hydrocarbon, an ether bond (—O—), an imino bond (—NH—), an amide bond (—CONH—), an ester bond (—COO— or —OCO—), a sulfonamide bond ( -NHSO ₂ - or _-SO 2 NH-), a urethane bond (-NHCOO- or -OCONH-), ureylene bond (-NHCONH-), carbonate bond (-OCOO-), may intervene as the linking group .

Among these, W ¹³ is preferably a residue having 3 to 10 carbon atoms and having 3 hydrogen atoms removed from a linear saturated hydrocarbon, and further, an ether bond (- It is particularly preferred to include O-) as a linking group.

In (General Formula I-3), Z ¹³ represents a hydroxyl group or an amino group (—NH ₂ ). That is, when the desired (A) polymer has a urethane bond, a compound in which Z ¹³ is a hydroxyl group is used as the diol component, and when it has a urea bond, Z ¹³ is an amino group (—NH ₂ ). A compound may be used as a diamine component.

In the general formula (I-3), the polymer (A) having a repeating unit represented by the following general formula (U-a1-2) can be obtained by using a monomer in which Z ¹³ is a hydroxyl group. The said (A) polymer which has a repeating unit represented by general formula (U-a1-2) is one of the preferable forms of this invention.

In the general formula (U-a1-2), Y ¹ and n are synonymous with the above-mentioned (general formula I) including the preferred range, and W ¹³ is preferably the same as the above-mentioned (general formula I-3). It is synonymous including the range.

  Specific examples of the monomer represented by (General Formula I-3) that can be used in the present invention are shown below. Note that the present invention is not limited to these examples.

  As the compound of the general formula I-3, a commercially available compound can be appropriately selected and used as it is, but a compound having an epoxy group at the end and having a fluoroalkyl group is disclosed in, for example, JP-A-2005-126357. The diol compound can be obtained in a high yield by treating with an acid catalyst based on the method described in 1).

  The compound containing an epoxy group at the terminal and having a fluoroalkyl group is available as a commercially available product. For example, E-1430, E-1630, E-5244, E-5444, E-manufactured by Daikin. 5644, E-7432 and the like.

((A2) group containing a siloxane structure)
The group containing a siloxane structure contained in the polymer (A) (surface segregation polymer) in the present invention is not particularly limited as long as it has a “—Si—O—Si—” structure. Preferably has a group represented by the following general formula (a2-1) in the side chain of the polymer (A).

In General Formula (a2-1), R ²¹ represents an alkyl group or an aryl group, and Z ²¹ represents a group represented by the following General Formula (a2-Z). ^Further, x 1, ^{x 2,} and ^{x 3} are integers their sum satisfies the 1 to 100, ^{y 1} is an integer of 1 to 50, * represents a position for coupling with the side chain of the polymer.

In the structural formula (a2-Z), R ²²² represents an unsubstituted alkyl group having 1 to 4 carbon atoms, and y ²² represents an integer of 1 to 100.

The alkyl group for R ²¹ preferably has 1 to 12 carbon atoms, and may have a linear structure or a branched structure. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group. Moreover, it is more preferable that it is a C1-C6 alkyl group, and it is further more preferable that it is a C1-C4 linear alkyl group.

The aryl group for R ²¹ preferably has 6 to 20 carbon atoms, and more preferably 6 to 14 carbon atoms. Specific examples of the aryl group for R ²¹ include a phenyl group, a biphenyl group, and a naphthyl group, and a phenyl group is more preferable.

x ¹ , x ² , and x ³ are preferably an integer of 5 to 100, and more preferably an integer of 5 to 50. Further, ^{y 1} is an integer of 1 to 50, preferably 5 to 50 integer, and more preferably, an integer of 5-30.

In the general formula (a2-Z), R ²²² is more preferably a methyl group, and y ²² is preferably an integer of 1 to 50, more preferably an integer of 1 to 20.

The method for introducing the structure of the general formula (a2-1) into the side chain of the polymer (A) is not particularly limited. For example, the monomer having the structure (a2-1) during the synthesis of the polymer (A) Is appropriately selected and applied, the structure (a2-1) can be introduced into the repeating unit of the obtained polymer.
Although the commercially available compound can be used for the monomer which has the structure of (a2-1), the desired structure contained in (a2-1) with respect to the commercially available monomer which does not have the structure of (a2-1). You may introduce and use suitably. There is no limitation on the method of introducing the structure (a2-1) into a commercially available monomer, and a known method may be applied as appropriate.

  The monomer having the structure (a2-1) can be appropriately selected according to the desired main chain structure of the polymer (A). For example, if the polymer has a (meth) acrylic structure in the main chain, It is preferable to use a monomer represented by the general formula (a2-2).

In the general formula (a2-2), R ²² represents a hydrogen atom, a methyl group, an ethyl group, or a halogen atom, X ²¹ represents a divalent linking group, and R ²³ represents a single bond or an alkylene group. To express. Z ²¹ , R ²¹ , x ¹ , x ² , x ³ , and y ¹ are synonymous with the above-mentioned general formula (a2-1) and the preferable range.

In General Formula (a2-2), R ²² is a hydrogen atom, a methyl group, an ethyl group, or a halogen atom, more preferably a hydrogen atom or a methyl group, and still more preferably a methyl group.

In the general formula (a2-2), examples of the divalent linking group as X ²¹ include —O—, —S—, —N (R ⁴ ) —, and the like. Among these, -O- is more preferable.
Here, R ⁴ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group may be a linear structure or a branched structure, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Preferably, they are a hydrogen atom and a methyl group.

Further, the alkylene group for R ²³ preferably has 1 to 20 carbon atoms. The alkylene group may have a linear structure or a branched structure. Moreover, even if it has a substituent, it may be unsubstituted. Examples of the substituent that may have include a halogen atom.

Among these, it is preferred that R ²³ is an unsubstituted alkylene group having 1 to 20 carbon atoms, more preferably an unsubstituted alkylene group having 1 to 10 carbon atoms, more preferably from 2 to carbon atoms 6 unsubstituted linear alkylene groups. Specific examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, an octylene group, and a decylene group.

In the alkylene group of R ²³ , an ether bond (—O—), an imino bond (—NH—), an amide bond (—CONH—), an ester bond (—COO— or —OCO—), a sulfonamide bond (—NHSO ₂ — or —SO ₂ NH—), urethane bond (—NHCOO— or —OCONH—), ureylene bond (—NHCONH—), carbonate bond (—OCOO—) may be interposed as a linking group. Good.

R ²³ is particularly preferably an unsubstituted linear alkylene group having 2 to 6 carbon atoms.

  By using the monomer represented by the general formula (a2-2), the polymer (A) having a repeating unit represented by the following general formula (U-a2-1) can be obtained. The (A) polymer preferably has one repeating unit represented by the general formula (U-a2-1).

In the general formula (U-a2-1), Z ²¹ , R ²¹ , x ¹ , x ² , x ³ , and y ¹ are synonymous with the above general formula (a2-1), including the preferred range, R ²² , X ²¹ , and R ²³ are synonymous with the aforementioned general formula (a2-2), including the preferred range.

  Hereinafter, specific examples of the monomer represented by formula (a2-2) used in the present invention are shown. However, the present invention is not limited to these. In the exemplified compounds, x is an integer of 5 to 100.

  In the case where the polymer (A) is a so-called polyurethane resin or polyurea resin containing a urethane bond (-NHCOO- or -OCONH-) or a urea bond (-NHCONH-) in the main chain structure, As the component or diamine component, it is preferable to use a monomer represented by the following general formula (a2-3). That is, when the (A) polymer has a urethane bond, the compound of the general formula (a2-3) may be used as a diol component, and when it has a urea bond, it may be used as a diamine component.

In the above general formula (a2-3), Z ²³ represents a hydroxyl group or an amino group (—NH ₂ ), and W ²³ represents a residue obtained by removing three hydrogen atoms from a saturated hydrocarbon. Z ²¹ , R ²¹ , x ¹ , x ² , x ³ , and y ¹ are synonymous with the above-mentioned general formula (a2-1) and the preferable range.

In the general formula (a2-3), W ²³ represents a residue obtained by removing three hydrogen atoms from a saturated hydrocarbon. The saturated hydrocarbon preferably has 3 to 30 carbon atoms, and may be linear, branched or cyclic. As for carbon number, it is more preferable that it is 3-25, and it is still more preferable that it is 3-10.
Specific examples include a residue obtained by removing three hydrogen atoms from a compound such as propane, 2-methylpropane, butane, pentane, and cyclohexane. In the saturated hydrocarbon, an ether bond (—O—), an imino bond (—NH—), an amide bond (—CONH—), an ester bond (—COO— or —OCO—), a sulfonamide bond ( -NHSO ₂ - or _-SO 2 NH-), a urethane bond (-NHCOO- or -OCONH-), ureylene bond (-NHCONH-), carbonate bond (-OCOO-), may intervene as the linking group .

Among these, W ²³ is preferably a residue having 3 to 10 carbon atoms and having 3 hydrogen atoms removed from a linear saturated hydrocarbon, and further, an ether bond (- It is particularly preferred to include O-) as a linking group.

In the general formula ^{(a2-3), Z 23} is a hydroxyl group, or an amino group (-NH _2). That is, when the desired polymer (A) has a urethane bond, a compound in which Z ²³ is a hydroxyl group is used as the diol component, and when it has a urea bond, Z ²³ is an amino group (—NH ₂ ). A compound may be used as a diamine component.

In the general formula ^(a2-3), by using a monomer ^{Z 23} is a hydroxyl group, it is possible to obtain the (A) polymer having a repeating unit represented by the following general formula (U-a2-2). The said (A) polymer which has a repeating unit represented by general formula (U-a2-2) is one of the preferable forms of this invention.

In the general formula (U-a2-2), Z ²¹ , R ²¹ , x ¹ , x ² , x ³ , and y ¹ are synonymous with the above-described general formula (a2-1) including a preferable range, W ²³ has the same meaning, including the preferred ranges as described above for the general formula (a2-3).

  Specific examples of the monomer represented by the general formula (a2-3) that can be used in the present invention are shown below. Note that the present invention is not limited to these examples. In the exemplified compounds, x is an integer of 5 to 100.

  As the compound of the general formula (a2-3), commercially available compounds can be appropriately selected and used as they are. For example, x-22-176DX, X-22-176F (both Shin-Etsu Chemical Co., Ltd.) Manufactured), FM-DA11, FM-DA21, FM-DA26 (all manufactured by Chisso Corporation), and the like.

((A3) long chain alkyl group)
The (a3) long chain alkyl group contained in the surface segregation polymer in the present invention is preferably an alkyl group having 10 or more carbon atoms. More preferably, it is a C10-40 alkyl group, More preferably, it is a C10-30 alkyl group, Most preferably, it is a C10-20 alkyl group. The long-chain alkyl group may contain a branched structure or a cyclic structure, but the number of carbon atoms in the straight-chain structure is preferably in the above-mentioned range, and all of the straight-chain structures are more preferable. That is, it is more preferably a long-chain alkyl group having a linear structure and having the above-mentioned preferable carbon number.

  Specifically, it is preferable that the side chain of the polymer (A) has a group represented by the following general formula (a3-1).

In formula _{(a3-1), n a3} represents an integer of 10 or more, * represents a position for coupling with the side chain of the polymer.

In general formula (a3-1), _na3 is preferably an integer of 10 to 40, more preferably an integer of 10 to 30, and most preferably an integer of 10 to 20.

The method for introducing the structure of the general formula (a3-1) into the side chain of the polymer (A) is not particularly limited. For example, the monomer having the structure (a3-1) during the synthesis of the polymer (A) Is appropriately selected and applied, the structure (a3-1) can be introduced into the repeating unit of the obtained polymer.
Although the commercially available compound can be used for the monomer which has the structure of (a3-1), the desired structure contained in (a3-1) is compared with the commercially available monomer which does not have the structure of (a3-1). You may introduce and use suitably. There is no limitation on the method of introducing the structure (a3-1) into a commercially available monomer, and a known method may be applied as appropriate.

  The monomer having the structure (a3-1) can be appropriately selected according to the desired main chain structure of the polymer (A). For example, if the polymer has a (meth) acrylic structure in the main chain, It is preferable to use a monomer represented by the general formula (a3-2).

In the general formula (a3-2), R ³² represents a hydrogen atom, a methyl group, an ethyl group, or a halogen atom, X ³¹ represents a divalent linking group, and R ³³ represents a single bond or an alkyleneoxy group. Represents. Moreover, _na3 is synonymous also including the above-mentioned general formula (a3-1) and a preferable range.

In General Formula (a3-2), R ³² represents a hydrogen atom, a methyl group, an ethyl group, or a halogen atom, more preferably a hydrogen atom or a methyl group, and still more preferably a methyl group.

In the general formula (a3-2), examples of the divalent linking group as X ³¹ include —O—, —S—, —N (R ⁴ ) —, and the like. Among these, -O- is more preferable.
Here, R ⁴ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group may be a linear structure or a branched structure, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Preferably, they are a hydrogen atom and a methyl group.

Further, the alkyleneoxy group for R ³³ preferably has 1 to 4 carbon atoms. The alkyleneoxy group may have a branched structure. Moreover, even if it has a substituent, it may be unsubstituted. Examples of the substituent that may have include a halogen atom.

Among these, R ³³ is preferably an unsubstituted alkyleneoxy group having 1 to 4 carbon atoms, more preferably an unsubstituted alkyleneoxy group having 1 to 3 carbon atoms, and further preferably a carbon number. 1-2 unsubstituted linear alkyleneoxy groups. Specific examples of the alkyleneoxy group include a methyleneoxy group, an ethyleneoxy group, a propyleneoxy group, a butyleneoxy group, and the like.

In the alkyleneoxy group of R ³³ , an imino bond (—NH—), an amide bond (—CONH—), an ester bond (—COO— or —OCO—), a sulfonamide bond (—NHSO ₂ — or — SO ₂ NH—), urethane bond (—NHCOO— or —OCONH—), ureylene bond (—NHCONH—), carbonate bond (—OCOO—), and ether bond (—O—) as a bonding group. Good.

R ³³ is particularly preferably an unsubstituted linear alkyleneoxy group having 1 to 4 carbon atoms.

  By using the monomer represented by the general formula (a3-2), the polymer (A) having a repeating unit represented by the following general formula (U-a3-1) can be obtained. It is one of the preferred forms that the polymer (A) has a repeating unit represented by the general formula (U-a3-1).

In Formula _{(U-a3-1), n a3} are synonymous, including preferred ranges and the above-mentioned general formula ^{(a3-1), R 32, X} 31, and ^{R 33} are the aforementioned general formula ( It is synonymous with a3-2) and a preferable range.

  Hereinafter, specific examples of the monomer represented by formula (a3-2) used in the present invention are shown. However, the present invention is not limited to these.

  In the case where the polymer (A) is a so-called polyurethane resin or polyurea resin containing a urethane bond (-NHCOO- or -OCONH-) or a urea bond (-NHCONH-) in the main chain structure, As the component or diamine component, it is preferable to use a monomer represented by the following general formula (a3-3). That is, when the polymer (A) has a urethane bond, the compound of the general formula (a3-3) is used as a diol component, and when it has a urea bond, it may be used as a diamine component.

In the general formula (a3-3), Z ³³ represents a hydroxyl group or an amino group (-NH ^{_2), W 33} represents a three a residue obtained by removing a hydrogen atom from a saturated hydrocarbon. Moreover, _na3 is synonymous also including the above-mentioned general formula (a3-1) and a preferable range.

In the general formula (a3-3), W ³³ represents a residue obtained by removing three hydrogen atoms from a saturated hydrocarbon. The saturated hydrocarbon preferably has 2 to 10 carbon atoms, and may be linear, branched or cyclic. As for carbon number, it is more preferable that it is 2-7, and it is still more preferable that it is 2-5.
Specific examples include a residue obtained by removing three hydrogen atoms from a compound such as propane, 2-methylpropane, butane, pentane, and cyclohexane. In the saturated hydrocarbon, an ether bond (—O—), an imino bond (—NH—), an amide bond (—CONH—), an ester bond (—COO— or —OCO—), a sulfonamide bond ( -NHSO ₂ - or _-SO 2 NH-), a urethane bond (-NHCOO- or -OCONH-), ureylene bond (-NHCONH-), carbonate bond (-OCOO-), may intervene as the linking group .

Among these, W ³³ is preferably a residue having 3 to 5 carbon atoms and having three hydrogen atoms removed from a linear saturated hydrocarbon.

In the general formula ^{(a3-3), Z 33} is a hydroxyl group, or an amino group (-NH _2). That is, when the desired polymer (A) has a urethane bond, a compound in which Z ³³ is a hydroxyl group is used as the diol component, and when it has a urea bond, Z ³³ is an amino group (—NH ₂ ). A compound may be used as a diamine component.

In formula ^(a3-3), by using a monomer ^{Z 33} is a hydroxyl group, it is possible to obtain the (A) polymer having a repeating unit represented by the following general formula (U-a3-2). The said (A) polymer which has a repeating unit represented by general formula (U-a3-2) is one of the preferable forms of this invention.

In Formula _{(U-a3-2), n a3} are synonymous, including preferred ranges and the above-mentioned general formula ^{(a3-1), W 33} is also preferable range with the aforementioned general formula (a3-3) It is synonymous including.

  Specific examples of the monomer represented by the general formula (a3-3) that can be used in the present invention are shown below. Note that the present invention is not limited to these examples.

  As the compound of the general formula (a3-3), a commercially available compound can be appropriately selected and used as it is. For example, 1,2-dodecanediol (manufactured by ALDRICH), 1,2-hexadecanediol (Tokyo Chemical Industry) Etc.).

  Among the (a1) polymer of the present invention, the (a1) fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long-chain alkyl group, the side chain has (a1) fluorine-substituted It preferably has a hydrocarbon group or (a2) a group containing a siloxane structure, and (a2) particularly preferably has a group containing a siloxane structure.

In the present invention, the content in the surface segregation polymer of at least one group selected from the group consisting of (a1) a fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long-chain alkyl group ( That is, the value obtained by dividing the mass of the raw material compound used for introducing the group (a1), (a2), or (a3) by the total mass of the polymer (A) is 1% by mass to 60%, respectively. % By mass is preferable, more preferably 2% by mass to 50% by mass, and still more preferably 3% by mass to 40% by mass.
By setting it as the said range, the effect of this invention can be improved more.

  In addition, at least one group selected from (a1) a fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long-chain alkyl group is 2 or more in the side chain in the (A) polymer. It may be included.

(Polymerizable group)
In addition to the (a1) fluorine-substituted hydrocarbon group, the (a2) group containing a siloxane structure, and the (a3) long-chain alkyl group, the surface segregation polymer in the present invention further includes a polymerizable group as a side chain. Have. The polymerizable group is particularly preferably a radical polymerizable group.

Examples of the radical polymerizable group include a polymerizable group having an ethylenically unsaturated bond capable of radical polymerization.
Examples of polymerizable groups having an ethylenically unsaturated bond capable of radical polymerization include acrylic acid ester groups, methacrylic acid ester groups, itaconic acid ester groups, crotonic acid ester groups, isocrotonic acid ester groups, and maleic acid ester groups. Examples thereof include radically polymerizable groups such as unsaturated carboxylic acid ester groups and styrene groups. Among these, a methacrylic acid ester group and an acrylic acid ester group (that is, a (meth) acrylic acid ester group) are preferable.

  The content of the radical polymerizable group is preferably 0.3 mmol / g or more in the surface segregation polymer, more preferably 0.5 mmol / g to 6 mmol / g, and still more preferably 1 to 3 mmol / g. It is.

  As a method for introducing a radically polymerizable group into a surface segregation polymer, a monomer in which a reaction is blocked with a double bond of a radically polymerizable group using a protective group, this monomer is copolymerized, and the protective group is removed. Examples thereof include a method of forming a radical polymerizable group (double bond) and a method of introducing a low molecular compound having a radical polymerizable group into a surface segregation polymer by a polymer reaction.

(Main chain structure)
Examples of the main chain structure of the surface segregation polymer contained in the ink composition of the present invention include acrylic resin, methacrylic resin, styryl resin, polyester resin, polyurethane resin, polycarbonate resin, polyamide resin, polyacetal resin, and phenol / formaldehyde. Condensation resins, polyvinylphenol resins, maleic anhydride / α-olefin resins, α-hetero-substituted methacrylic resins, and the like can be used.
Of these, methacrylic resin, acrylic resin, polyurethane resin, and polyurea resin are more preferable.
That is, the surface segregation polymer in the present invention repeats (Aspect A1) (meth) acrylic structure (—C═C—COO— or —C═C (—CH ₃ ) —COO—) in the main chain structure. It is preferable that it is either the aspect containing as a unit or the aspect containing (urethane A structure (-NHCOO- or -OCONH-) or a urea structure (-NHCONH-) as a repeating unit.

  As the main chain structure of the surface segregation polymer, (Aspect A2) When having an aspect including a urethane structure (—NHCOO— or —OCONH—) or a urea structure (—NHCONH—) as a repeating unit, the main chain structure is: A polyurethane structure can be formed by reacting a diisocyanate and a polyol component such as a diol, and a polyurea structure can be formed by reacting the diisocyanate and a diamine component.

  Examples of the diisocyanate that can form a polyurethane structure or a polyurea structure include tolylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, norbornene diisocyanate, dicyclohexylmethane-4,4-diisocyanate, diphenylmethane-4,4. -Diisocyanate, dimer acid diisocyanate, etc. are mentioned.

Examples of polyol components that can form a polyurethane structure include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,4-butanediol, 2,3-butanediol, 1,3-butanediol, neopentyl glycol, and methylpentane. Diol, 1,6-hexanediol, trimethylhexamethylenediol, 2-methyloctanediol, 1,9-nonanediol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, polycaprolactone diol, polycarbonate diol, glycerin, Examples include trimethylolpropane, trimethyloloctane, pentaerythritol, polytetramethylene glycol and the like.
Among these, it is preferable to use a polyol having a molecular weight of 4000 or less.

  Examples of the diamine that can form a polyurea structure include ethylenediamine, N-alkylethylenediamine, propylenediamine, 2,2-dimethyl-1,3-propanediamine, N-alkylpropylenediamine, butylenediamine, N-alkylbutylenediamine, Pentanediamine, hexamethylenediamine, N-alkylhexamethylenediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, dodecanediamine, hexadecanediamine, tolylenediamine, xylylenediamine, diaminodiphenylmethane, diaminodicyclohexylmethane, phenylenediamine, cyclohexane Sylenediamine, bis (aminomethyl) cyclohexane, diaminodiphenylsulfone, isophoronediamine, 2-butyl 2-ethyl-1,5-pentamethylenediamine, 2,2,4- or 2,4,4-trimethyl-1,6-hexamethylenediamine, 2-aminopropylcyclohexylamine, 3 (4) -aminomethyl- Examples thereof include 1-methylcyclohexylamine, 1,4-diamino-4-methylpentane, amine-terminated polyoxyalkylene polyol (known as Jeffamines), and amine-terminated polytetramethylene glycol.

  When synthesizing a polymer containing a urethane bond (-NHCOO-, or -OCONH-) or a urea bond (-NHCONH-) in the main chain structure in the present invention, a diol having a polymerizable group or a polymerizable group is added. By using the diisocyanate having as a raw material, a polymerizable urethane compound can be obtained by a one-step reaction.

  The weight average molecular weight of the surface segregation polymer is preferably 3,000 to 200,000, more preferably 5,000 to 100,000, and still more preferably 10,000 to 80,000.

  Further, the content of the polymer (A) contained in the ink composition of the present invention is preferably 0.2% by mass to 9% by mass, and preferably 0.2% by mass to 5% by mass in the total solid content of the ink composition. Is more preferable, and 0.2 mass%-3 mass% is still more preferable.

Below, the preferable specific example of the surface segregation polymer in this invention is given. (A-1 to a-22) is an embodiment in which the (aspect A1) (meth) acrylic structure (—C═C—COO— or —C═C (—CH ₃ ) —COO—) is included as a repeating unit. Yes, (A-1) to (A-12) are the embodiments (Aspect A2) containing the urethane structure (—NHCOO— or —OCONH—) or the urea structure (—NHCONH—) as a repeating unit. The present invention is not limited to these specific examples.

(B) Silica fine particles having a polymerizable group The ink composition of the invention contains (B) silica fine particles having a polymerizable group as an essential component. Specifically, particles in which a polymerizable group is bonded to the surface of silica fine particles are preferable. Details will be described below.

~ Silica fine particles ~
The silica fine particles that can be used in the present invention are not particularly limited as long as they are silicon oxide fine particles, but the number average particle diameter is preferably 0.001 μm to 2.0 μm, preferably 0.001 μm to 0.2 μm. Is more preferable, and 0.001 μm to 0.1 μm is more preferable. As a method for measuring the number average particle size of the silica fine particles, for example, a nano particle size distribution measuring device SALD-7100 (manufactured by Shimadzu Corporation) can be used.

  The silica fine particles may be either dry powder or colloidal silica particles dispersed in a dispersion medium (water or organic solvent), but for the purpose of particularly pursuing transparency. The use of colloidal silica fine particles (hereinafter also referred to as colloidal silica) is preferred.

  When the colloidal silica dispersion medium is water, the hydrogen ion concentration is preferably in the range of 2 to 10, more preferably 3 to 7, as the pH value. When the dispersion medium of colloidal silica is an organic solvent, methanol, isopropyl alcohol, ethylene glycol, butanol, ethylene glycol monopropyl ether, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene An organic solvent such as dimethylformamide can be used. These organic solvents may be used as other compatible organic solvents or as a mixture with water. Among these, preferred organic solvents as the dispersion medium include methanol, isopropyl alcohol, methyl ethyl ketone, xylene and the like.

As the silica fine particles, commercially available products can be used as they are. For example, as colloidal silica, methanol silica sol, IPA-ST, MEK-ST, XBA-ST, DMAC-ST, ST-UP, ST-OUP ST-20, ST-40, ST-C, ST-N, ST-O, ST-50, ST-OL (manufactured by Nissan Chemical Industries, Ltd.) and the like. Examples of the powdery silica fine particles include AEROSIL130, AEROSIL300, AEROSIL380, AEROSILTT600, AEROSILOX50 (manufactured by Nippon Aerosil Co., Ltd.), SYLYSIA470 (manufactured by Fuji Silysia Co., Ltd.), and the like.
The shape of the silica fine particles is not particularly limited and can be appropriately selected from spherical, hollow, porous, rod-like, plate-like, fiber-like, or irregularly shaped powders. It is more preferable to select the silica fine particles.

-Polymerizable group-
In the present invention, the polymerizable group introduced onto the surface of the silica fine particles is preferably a radical polymerizable group, and specifically includes a polymerizable group having an ethylenically unsaturated bond capable of radical polymerization.
Examples of polymerizable groups having an ethylenically unsaturated bond capable of radical polymerization include acrylic acid ester groups, methacrylic acid ester groups, itaconic acid ester groups, crotonic acid ester groups, isocrotonic acid ester groups, and maleic acid ester groups. Examples thereof include radically polymerizable groups such as unsaturated carboxylic acid ester groups and styrene groups. Among these, a methacrylic acid ester group and an acrylic acid ester group (that is, a (meth) acrylic acid ester group) are preferable. Moreover, in the silica fine particle which has (B) polymeric group, it is preferable to have the said radical polymeric group 0.1-10 mmol / g, and it is more preferable to have 0.2-5 mmol / g.

-Method for synthesizing silica fine particles having a polymerizable group-
Although there is no limitation on the method for synthesizing the silica fine particles having a polymerizable group in the present invention, for example, according to the methods described in JP 2000-230107 A, JP 9-100111 A, Patent 3915886, etc. Silica fine particles can be introduced into the aforementioned polymerizable group.
That is, for example, by introducing a radical polymerizable group on the surface of silica fine particles by mixing and condensing an organic compound having a radical polymerizable group and an alkoxysilane moiety and silica fine particles (preferably spherical). Alternatively, silica fine particles having a polymerizable group can be obtained by using a self-condensation reaction of an organic compound having a radical polymerizable group and an alkoxysilane moiety. Among them, a method in which an organic compound having a radical polymerizable group and an alkoxysilane moiety and silica fine particles (preferably spherical) are mixed and subjected to a condensation reaction is preferable.
In the organic compound having a radical polymerizable group and an alkoxysilane moiety, the alkoxysilane moiety is bonded to the surface of the silica fine particle by a condensation reaction, and the radical polymerizable group is bonded to the silica fine particle through the alkoxysilane moiety.

  The number of radical polymerizable groups in one molecule of the organic compound having a radical polymerizable group and an alkoxysilane moiety is preferably 1 to 20, more preferably 1 to 10, and preferably 1 to 5. More preferably it is.

  Moreover, it is preferable that the molecular weight of the organic compound which has a radically polymerizable group and an alkoxysilane site | part is 20-10,000, More preferably, it is 40-5000, Most preferably, it is 50-1000.

  The silica fine particles having a polymerizable group (B) can be appropriately synthesized and used as described above, but commercially available products can also be used. For example, Desolite Z7501 manufactured by JSR Corporation. Z7503 and the like are particularly preferable. These commercially available products may be used as they are by adding them to the ink composition, but it is more preferable to use them by distilling off the contained solvent under reduced pressure. More specifically, (C) other polymerizable compound (polymerizable compound other than (A) and (B) described later) is added to these commercially available products, and the product is derived from the commercially available products by distillation under reduced pressure. It is preferable to use after removing only the solvent component.

<Polymerizable compound other than (C) (A) polymer (surface segregation polymer) and (B) silica particles having a polymerizable group>
In the ink composition of the present invention, the (A) polymer (with side chain containing a polymerizable group, (a1) a fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long-chain alkyl group. And a polymer having at least one group selected from the above (B) silica fine particles having a polymerizable group, and in addition to these, known polymerizable compounds generally used for curable compositions are contained. . Specifically, (a1) a fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a polymerizable compound that does not contain any long-chain alkyl group and is an organic compound To do.
Hereinafter, such a polymerizable compound is also appropriately referred to as (C) another polymerizable compound. (C) The other polymerizable compound is preferably a radical polymerizable compound.

(C-1) Radical polymerizable compound (C) The (C-1) radical polymerizable compound used as another polymerizable compound is a compound having an ethylenically unsaturated bond capable of radical polymerization, A compound having at least one radically polymerizable ethylenically unsaturated bond, which does not include the aforementioned (a1) fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long-chain alkyl group Any organic compound may be used, including those having chemical forms such as monomers, oligomers, and polymers. Only one kind of radically polymerizable compound may be used, or two or more kinds thereof may be used in combination at an arbitrary ratio in order to improve desired properties.

  Examples of the polymerizable compound having an ethylenically unsaturated bond capable of radical polymerization include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, and salts thereof, Examples thereof include radically polymerizable compounds such as anhydrides having a saturated group, acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.

  Specifically, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, bis (4-acryloxypolyethoxyphenyl) propane, neopentyl glycol Diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol Tetraacrylate, dipentaery Acrylic acid derivatives such as lithol tetraacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, N-methylol acrylamide, diacetone acrylamide, epoxy acrylate, methyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate , Lauryl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylol Methacryl derivatives such as tan trimethacrylate, trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, and other derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, triallyl trimellitate More specifically, Shinzo Yamashita, “Cross-linking agent handbook”, (1981 Taiseisha); Kato Kiyomi, “UV / EB curing handbook (raw material)” (1985, Polymer publication) ); Rad-Tech Study Group, “Application and Market of UV / EB Curing Technology”, p. 79, (1989, CMC); Eiichiro Takiyama, “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun) Commercially available products described in the above, or radically polymerizable or crosslinkable monomers known in the industry, Ligomers and polymers can be used.

  Examples of the radical polymerizable compound include those disclosed in JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, JP-A-10-863, JP-A-9-134011, and the like. Photo-curable polymerizable compound materials used for the described photopolymerizable compositions are known, and these can also be applied to the ink composition of the present invention.

Furthermore, it is also preferable to use a vinyl ether compound as the radical polymerizable compound. Suitable vinyl ether compounds include, for example, ethylene glycol divinyl ether, ethylene glycol monovinyl ether, diethylene glycol divinyl ether, triethylene glycol monovinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol. Di- or trivinyl ether compounds such as divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, hydroxyethyl monovinyl ether, hydroxynonyl monovinyl ether, trimethylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octade Monovinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether-O-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, octadecyl vinyl ether, etc. Examples include vinyl ether compounds.
Of these vinyl ether compounds, divinyl ether compounds and trivinyl ether compounds are preferable from the viewpoints of curability, adhesion, and surface hardness, and divinyl ether compounds are particularly preferable. A vinyl ether compound may be used individually by 1 type, and may be used in combination of 2 or more type as appropriate.

In the total solid content of the ink composition of the present invention, the content of (C) another polymerizable compound (preferably (C-1) radical polymerizable compound) is preferably 45% by mass to 80% by mass. More preferably, it is 50 mass%-80 mass%, More preferably, it is 55 mass%-75 mass%.
In order to further improve the flexibility of the coating film, the content of the monofunctional monomer in (C) the other polymerizable compound (preferably a radical polymerizable compound) is preferably 60% by mass to 100% by mass, and 70 The mass% is more preferably 100% by mass, and further preferably 80% by mass to 100% by mass.

  Preferable examples of the monofunctional monomer include phenoxyethyl acrylate, N-vinylcaprolactam, tetrahydrofurfuryl acrylate, cyclic trimethylolpropane formal acrylate, isobornyl acrylate, and the like, more preferably phenoxyethyl acrylate. , N-vinylcaprolactam, and isobornyl acrylate.

(C-2) A compound having a ring-opening polymerization reaction site and a radical polymerization reaction site (C) As another polymerizable compound, a compound having a ring-opening polymerization reaction site and a radical polymerization reaction site can also be used. . As such a compound, Bremermer G (manufactured by Nippon Oil & Fats Co., Ltd.), OXE-10 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), OXE-30 (manufactured by Osaka Organic Chemical Industry Co., Ltd.) are commercially available. ), Cyclomer A400 (manufactured by Daicel Chemical Co., Ltd.), 4HBAGE (manufactured by Nippon Kasei Chemical Co., Ltd.), GBLA (manufactured by Osaka Organic Chemical Industry Co., Ltd.), M-GMA (manufactured by Daicel Chemical Industries, Ltd.) ), Cyclomer M100 (manufactured by Daicel Cytec Co., Ltd.) and the like.
Examples of the ring-opening polymerizable compound having a radical polymerizable group include the following compounds, but the present invention is not limited thereto.

The present invention relates to the (B) silica fine particles with respect to the total content (TX) of the (A) polymer, the (B) silica fine particles, and the (C) polymerizable compound (other polymerizable compounds). 0.1 mass% to 30 mass% (solid content concentration) is included, and the content of the (B) silica fine particles is preferably 0.1 mass% to 20 mass% (solid content concentration). More preferably, it is 0.1 mass%-10 mass% (solid content concentration). The effect of this invention can be improved more by making content of the silica fine particle which has the said (B) polymeric group into the above-mentioned preferable range.
The content of the polymer (A) with respect to the total content (TX) is preferably 0.2% by mass to 10% by mass, and more preferably 0.2% by mass to 5% by mass. The content is more preferably 0.2% by mass to 3% by mass.
The content of the other polymerizable compound (C) with respect to the total content (TX) is preferably 60% by mass to 99.7% by mass, and 75% by mass to 99.6% by mass. It is more preferable, and it is still more preferable that it is 87 mass%-99.5 mass%.

  Although the mechanism of the present invention is not clear, the present inventors infer as follows. That is, the (A) polymer has at least one of (a1) a fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long-chain alkyl group. The (B) polymerizable fine particle-containing silica fine particles are incorporated into (A) the polymer and polymerized to form a high hardness film on the surface layer of the cured film. On the other hand, in the inner layer portion of the cured film, the presence of the polymer (A) is relatively small, and it is considered that the silica fine particles having the polymerizable group (B) that is incorporated into the polymer (A) and polymerized are also few. Therefore, it is considered that flexibility is imparted to the inner layer portion, and the surface hardness and flexibility of the image portion are adjusted to an appropriate range so that cracking of the image portion can be prevented even with a large stress. However, the above-mentioned mechanism is inference, and the present invention is not limited to this.

<(D) Polymerization initiator>
The ink composition of the present invention contains (D) a polymerization initiator. (D) A polymerization initiator is a compound which produces | generates a polymerization start seed | species by irradiation of an active energy ray, and can select and use a well-known polymerization initiator suitably.
Here, the active energy ray is not particularly limited as long as it can impart energy capable of generating a starting species in the ink composition by irradiation, and α ray, γ ray, X ray, ultraviolet ray, Infrared rays, visible rays, electron beams and the like are included. Among these, from the viewpoint of curing sensitivity and device availability, ultraviolet rays or electron beams are preferable, and ultraviolet rays are more preferable. Therefore, the ink composition of the present invention is preferably one that can be cured by irradiating ultraviolet rays as active energy rays. As a light source for generating ultraviolet rays, a light source having a light emission wavelength of 300 nm to 400 nm is preferable. Low pressure mercury lamps, high pressure mercury lamps, short arc discharge lamps, ultraviolet light emitting diodes, semiconductor lasers, fluorescent lamps and the like, which are known ultraviolet lamps, are used. A xenon lamp belonging to a high-pressure mercury lamp, a metal halide lamp, or a short arc discharge lamp belonging to a high-pressure discharge lamp is preferably used depending on the light amount and wavelength suitable for the initiator. Moreover, an ultraviolet light emitting diode is also preferably used from the viewpoint of energy saving.

(D-1) Radical polymerization initiator The (D) polymerization initiator is preferably (D-1) a radical polymerization initiator, such as (a) aromatic ketones and (b) acylphosphine oxide compounds. (C) aromatic onium salt compound, (d) organic peroxide, (e) thio compound, (f) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) Examples thereof include azinium compounds, (j) metallocene compounds, (k) active ester compounds, (l) compounds having a carbon halogen bond, and (m) alkylamine compounds.

  These radical polymerization initiators may be used alone or in combination of two or more of the compounds (a) to (m).

  Among these, (a) aromatic ketones, (b) acylphosphine compounds, and (e) thio compounds are preferred. Preferred examples of these are "RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY", J. P. FOUASSIER, J. F. RABEK (1993), pp. Examples include compounds having a benzophenone skeleton or a thioxanthone skeleton described in 77-117. More preferable examples include α-thiobenzophenone compounds described in JP-B-47-6416, benzoin ether compounds described in JP-B-47-3981, α-substituted benzoin compounds described in JP-B-47-22326, Benzoin derivatives described in JP-B-47-23664, aroylphosphonic acid esters described in JP-A-57-30704, dialkoxybenzophenones described in JP-B-60-26483, JP-B-60-26403, JP-A Benzoin ethers described in JP-A-62-81345, JP-B-1-34242, US Pat. No. 4,318,791, α-aminobenzophenones described in European Patent 0284561A1, JP-A-2-21152 P-Di (dimethylaminobenzoyl) benze Thio-substituted aromatic ketones described in JP-A-61-194062, acylphosphine sulfides described in JP-B-2-9597, acylphosphines described in JP-B-2-9596, and JP-B-63-61950 Thioxanthones, and coumarins described in JP-B-59-42864.

  Furthermore, in the present invention, it is particularly preferable to use an acylphosphine oxide compound as a polymerization initiator, and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (Irgacure 819: manufactured by BASF Japan), bis (2 , 6-Dimethoxybenzoyl) -2,4,4-trimethyl-pentylphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Darocur TPO: BASF Japan, Lucirin TPO: BASF) 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (Irgacure 907: manufactured by BASF Japan Ltd.), 2-benzyl-2-dimethylamino-1- (4-morpholinopheny ) -Butanone-1 (Irgacure 369: manufactured by BASF Japan Ltd.) is preferred.

  The content of the (D) polymerization initiator in the present invention is preferably in the range of 1% by mass to 50% by mass, and preferably in the range of 2% by mass to 40% by mass with respect to the total solid content of the ink composition of the present invention. More preferably, the range of 3% by mass to 20% by mass is even more preferable.

~ Other ingredients ~
In the ink composition of the present invention, in addition to the components (A) to (D), other components can be used in combination for the purpose of improving physical properties, as long as the effects of the present invention are not impaired.
Hereinafter, these optional components will be described below.

<(E) Colorant>
The ink composition of the present invention can form a visible image by adding the colorant (E). There is no restriction | limiting in particular in the coloring agent which can be used here, According to a use, well-known various color materials and (pigment, dye) can be selected suitably, and can be used. For example, when forming an image excellent in weather resistance, a pigment is preferable. As the dye, both water-soluble dyes and oil-soluble dyes can be used, but oil-soluble dyes are preferred.

(Pigment)
The pigment preferably used in the present invention will be described.
The pigment is not particularly limited, and all commercially available organic and inorganic pigments or pigments dispersed in an insoluble resin or the like as a dispersion medium, or the resin is grafted onto the pigment surface Can be used. Moreover, what dye | stained the resin particle with dye can be used.
Examples of these pigments include, for example, “Pigment Dictionary” (2000), edited by Seijiro Ito. Herbst, K.M. Hunger “Industrial Organic Pigments”, JP 2002-12607 A, JP 2002-188025 A, JP 2003-26978 A, and JP 2003-342503 A3.

  Specific examples of organic pigments and inorganic pigments that can be used in the present invention include C.I. I. Pigment Yellow 1 (Fast Yellow G etc.), C.I. I. A monoazo pigment such as C.I. Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow AAA, etc.), C.I. I. Disazo pigments such as C.I. Pigment Yellow 17; I. Non-benzidine type azo pigments such as CI Pigment Yellow 180; I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Condensed azo pigments such as CI Pigment Yellow 95 (Condensed Azo Yellow GR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Yellow 115 (such as quinoline yellow lake); I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake, etc.), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and quinophthalone yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (nickel nitroso yellow, etc.); I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.).

  C. As a thing which exhibits red or magenta color, C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as C.I. Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Azo lake pigments such as C.I. Pigment Red 57: 1 (Brilliant Carmine 6B); I. Condensed azo pigments such as C.I. Pigment Red 144 (condensed azo red BR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Red 174 (Phloxine B Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Red 81 (Rhodamine 6G 'lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Red 177 (eg, dianthraquinonyl red); I. Thioindigo pigments such as C.I. Pigment Red 88 (Thioindigo Bordeaux, etc.); I. Perinone pigments such as C.I. Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (perylene scarlet, etc.); I. Pigment violet 19 (unsubstituted quinacridone), C.I. I. Quinacridone pigments such as CI Pigment Red 122 (quinacridone magenta, etc.); I. Isoindolinone pigments such as CI Pigment Red 180 (isoindolinone red 2BLT, etc.); I. And alizarin lake pigments such as CI Pigment Red 83 (Mada Lake, etc.).

  As a pigment exhibiting blue or cyan, C.I. I. Disazo pigments such as C.I. Pigment Blue 25 (Dianisidine Blue, etc.); I. Phthalocyanine pigments such as C.I. Pigment Blue 15 (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (Peacock Blue Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Blue 1 (Viclotia Pure Blue BO Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).

As a pigment exhibiting green, C.I. I. Pigment green 7 (phthalocyanine green), C.I. I. Phthalocyanine pigments such as C.I. Pigment Green 36 (phthalocyanine green); I. And azo metal complex pigments such as CI Pigment Green 8 (Nitroso Green).
As a pigment exhibiting an orange color, C.I. I. An isoindoline pigment such as C.I. Pigment Orange 66 (isoindoline orange); I. And anthraquinone pigments such as CI Pigment Orange 51 (dichloropyrantron orange).

Examples of the black pigment include carbon black, titanium black, and aniline black.
Specific examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) or the like can be used.

  Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, and thus has a high hiding power and coloring power as a pigment. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the listed white pigments) may be used as necessary.

For dispersing the pigment, for example, a dispersion device such as a ball mill, a sand mill, an attritor, a roll mill, a jet mill, a homogenizer, a paint shaker, a kneader, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, or a wet jet mill is used. be able to.
It is also possible to add a dispersant when dispersing the pigment. Examples of the dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long-chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a high molecular weight unsaturated acid ester, a high molecular weight copolymer, a modified polyacrylate, an aliphatic Examples thereof include polyvalent carboxylic acids, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphate esters, and pigment derivatives. It is also preferable to use a commercially available polymer dispersant such as the Solsperse series from Zeneca.
Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment.
In the ink composition, as a dispersion medium for various components such as pigments, a solvent may be added, and the other polymerizable compound (C) which is a low molecular weight component without solvent is used as a dispersion medium. However, it is preferably solvent-free.

The average particle diameter of the pigment is preferably 0.02 to 0.4 μm, more preferably 0.02 to 0.1 μm, and more preferably 0.02 to 0.07 μm.
The selection of pigment, dispersant, dispersion medium, dispersion conditions, and filtration conditions are set so that the average particle diameter of the pigment particles is within the above-mentioned preferable range. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

(dye)
The dye used in the present invention is preferably oil-soluble. Specifically, it means that the solubility in water at 25 ° C. (the mass of the dye dissolved in 100 g of water) is 1 g or less, preferably 0.5 g or less, more preferably 0.1 g or less. Therefore, a so-called water-insoluble oil-soluble dye is preferably used.

The dye used in the present invention preferably has an oil-solubilizing group introduced into the above-described dye mother core in order to dissolve the necessary amount in the ink composition.
As the oil-solubilizing group, long chain, branched alkyl group, long chain, branched alkoxy group, long chain, branched alkylthio group, long chain, branched alkylsulfonyl group, long chain, branched acyloxy group, long chain, branched alkoxycarbonyl group, Long chain, branched acyl group, long chain, branched acylamino group long chain, branched alkylsulfonylamino group, long chain, branched alkylaminosulfonyl group and these long chains, aryl groups containing branched substituents, aryloxy groups, aryloxycarbonyl Group, arylcarbonyloxy group, arylaminocarbonyl group, arylaminosulfonyl group, arylsulfonylamino group and the like.
Also, for water-soluble dyes having carboxylic acid and sulfonic acid, long chain, branched alcohol, amine, phenol, aniline derivatives are used as oil-solubilizing alkoxycarbonyl groups, aryloxycarbonyl groups, alkylaminosulfonyl groups, A dye may be obtained by conversion to an arylaminosulfonyl group.

The oil-soluble dye preferably has a melting point of 200 ° C. or lower, more preferably has a melting point of 150 ° C. or lower, and still more preferably has a melting point of 100 ° C. or lower. By using an oil-soluble dye having a low melting point, the precipitation of dye crystals in the ink composition is suppressed, and the storage stability of the ink composition is improved.
Further, it is desirable that the oxidation potential is noble (high) in order to improve fading, particularly resistance to oxidizing substances such as ozone and curing characteristics. For this reason, as the oil-soluble dye used in the present invention, those having an oxidation potential of 1.0 V (vs SCE) or more are preferably used. The oxidation potential is preferably higher, the oxidation potential is more preferably 1.1 V (vs SCE) or more, and particularly preferably 1.15 V (vs SCE) or more.

As the yellow dye, a compound having a structure represented by the general formula (Y-I) described in JP-A No. 2004-250483 is preferable.
Particularly preferred dyes are dyes represented by the general formulas (Y-II) to (Y-IV) described in paragraph [0034] of JP-A No. 2004-250483. And the compounds described in paragraphs [0060] to [0071] of JP-A-250483. The oil-soluble dye of the general formula (Y-I) described in the publication may be used not only for yellow but also for inks of any color such as black ink and red ink.

The magenta dye is preferably a compound having a structure represented by the general formulas (3) and (4) described in JP-A No. 2002-114930. Specific examples include paragraphs of JP-A No. 2002-114930. Examples include the compounds described in [0054] to [0073].
Particularly preferred dyes are azo dyes represented by the general formulas (M-1) to (M-2) described in paragraph numbers [0084] to [0122] of JP-A No. 2002-121414, and specific examples Examples thereof include compounds described in paragraph numbers [0123] to [0132] of JP-A No. 2002-121414. The oil-soluble dyes represented by the general formulas (3), (4) and (M-1) to (M-2) described in the publication are used not only for magenta but also for any color ink such as black ink and red ink. May be.

Examples of the cyan dye include dyes represented by formulas (I) to (IV) described in JP-A No. 2001-181547, and paragraphs [0063] to [0078] of JP-A No. 2002-121414. The dyes represented by the general formulas (IV-1) to (IV-4) described above are preferred, and specific examples include paragraph numbers [0052] to [0066] of JP-A No. 2001-181547. Examples thereof include the compounds described in paragraph Nos. [0079] to [0081] of Kai 2002-121414.
Particularly preferred dyes are phthalocyanine dyes represented by general formulas (CI) and (C-II) described in paragraphs [0133] to [0196] of JP-A No. 2002-121414, A phthalocyanine dye represented by formula (C-II) is preferred. Specific examples thereof include the compounds described in JP-A No. 2002-121414, paragraph numbers [0198] to [0201]. The oil-soluble dyes of the formulas (I) to (IV), (IV-1) to (IV-4), (CI) and (C-II) are not only cyan but also black ink or green ink. The ink may be used for any color ink.

The colorant is preferably added in an amount of 1% by mass to 20% by mass in terms of solid content in the ink composition, and more preferably 2% by mass to 10% by mass.
When the content of the colorant is within the above range, it is preferable because a sufficient color density is obtained and appropriate curability is maintained.

<Ultraviolet absorber>
In the present invention, from the viewpoint of improving the weather resistance of an image to be obtained and preventing discoloration, an ultraviolet absorber can be used as long as the effects of the present invention are not impaired.
Examples of the ultraviolet absorber are described in JP-A-58-185679, JP-A-61-190537, JP-A-2-782, JP-A-5-97075, JP-A-9-34057, and the like. Benzotriazole compounds, benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194843, US Pat. No. 3,214,463, etc., JP-B Nos. 48-30492 and 56-21141 Cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621, JP The triazine compounds described in JP-A-8-501291, Research Disclosure No. Examples thereof include compounds described in No. 24239, compounds that emit ultraviolet light by absorbing ultraviolet rays typified by stilbene and benzoxazole compounds, so-called fluorescent brighteners, and the like.
The addition amount is appropriately selected according to the purpose, but is generally about 0.5% by mass to 15% by mass in terms of solid content.

<Sensitizer>
If necessary, a sensitizer may be added to the ink composition of the present invention for the purpose of increasing the photosensitive wavelength. Any sensitizer may be used as long as it sensitizes the polymerization initiator by an electron transfer mechanism or an energy transfer mechanism.

<Antioxidant>
In order to improve the stability of the ink composition, an antioxidant can be added as long as the effects of the present invention are not impaired. Examples of the antioxidant include European published patents, 223739, 309401, 309402, 310551, 310552, 359416, and 3435443. JP, 54-85535, 62-262417, 63-113536, 63-163351, JP-A-2-262654, JP-A-2-71262, Examples thereof include those described in Kaihei 3-121449, JP-A-5-61166, JP-A-5-119449, US Pat. No. 4,814,262, US Pat. No. 4,980,275, and the like.
The addition amount is appropriately selected according to the purpose, but is generally about 0.1% by mass to 8% by mass in terms of solid content.

<Anti-fading agent>
In the ink composition of the present invention, various organic and metal complex anti-fading agents can be used. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocycles. Examples of the metal complex anti-fading agent include nickel complexes and zinc complexes. No. 17643, No. VII, I to J, ibid. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of representative compounds described in JP-A-62-215272, pages 127 to 137 can be used. .
The addition amount is appropriately selected according to the purpose, but is generally about 0.1% by mass to 8% by mass in terms of solid content.

<Conductive salts>
Conductive salts such as potassium thiocyanate, lithium nitrate, ammonium thiocyanate, and dimethylamine hydrochloride can be added to the ink composition of the present invention for the purpose of controlling ejection properties.

<Solvent>
In order to improve the adhesion to the recording medium, it is also effective to add a very small amount of an organic solvent to the ink composition of the present invention.
Examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone, and diethyl ketone, alcohol solvents such as methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, and tert-butanol, and chlorine such as chloroform and methylene chloride. Solvents, aromatic solvents such as benzene and toluene, ester solvents such as ethyl acetate, butyl acetate and isopropyl acetate, ether solvents such as diethyl ether, tetrahydrofuran and dioxane, glycols such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether And ether solvents.
In this case, it is effective to add the solvent within a range that does not cause the problem of solvent resistance and VOC. % To 3% by mass.

<Water>
In addition, the ink composition of the present invention may contain a very small amount of water as long as it does not impair the effects of the present invention, but is a non-aqueous ink composition that does not substantially contain water. Is preferred. Specifically, the water content is preferably 3% by mass or less, more preferably 2% by mass or less, and most preferably 1% by mass or less based on the total amount of the ink composition.

<Polymer compound>
Various polymer compounds can be added to the ink composition of the present invention in order to adjust film physical properties. High molecular compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination. Of these, vinyl copolymer obtained by copolymerization of acrylic monomers is preferred. Furthermore, a copolymer containing “carboxyl group-containing monomer”, “methacrylic acid alkyl ester”, or “acrylic acid alkyl ester” as a structural unit is also preferably used as the copolymer composition of the polymer binder.

<Surfactant>
A surfactant may be added to the ink composition of the present invention.
Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound having no polymerizable group may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.

In addition to this, polymerization is not hindered to improve adhesion to recording media such as leveling additives, matting agents, waxes for adjusting film physical properties, polyolefins, PET, etc., if necessary. A tackifier or the like can be contained.
As the tackifier, specifically, a high molecular weight adhesive polymer described in JP-A-2001-49200, 5-6p (for example, (meth) acrylic acid and an alkyl group having 1 to 20 carbon atoms). An ester with an alcohol having, an ester of (meth) acrylic acid with an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer comprising an ester of (meth) acrylic acid with an aromatic alcohol having 6 to 14 carbon atoms) And a low molecular weight tackifying resin having a polymerizable unsaturated bond.

  The ink composition of the present invention preferably has an ink viscosity of 7 to 30 mPa · s, more preferably 7 to 20 mPa · s at the temperature at the time of ejection, and the composition ratio is appropriately adjusted to be in the above range. It is preferable to decide. The ink viscosity at 25 to 30 ° C. is 35 to 500 mPa · s, preferably 35 to 200 mPa · s. By setting the viscosity at room temperature high, even when a porous recording medium is used, ink penetration into the recording medium can be prevented, uncured monomer can be reduced, and odor can be reduced. Can be suppressed, and as a result, the image quality is improved.

  The surface tension of the ink composition of the present invention is preferably 20 mN / m to 30 mN / m, more preferably 23 mN / m to 28 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and uncoated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and the wettability is preferably 30 mN / m or less.

  The ink composition of the present invention thus prepared can be suitably used as an inkjet recording ink. When used as an ink for ink jet recording, the ink composition is ejected onto a recording medium by an ink jet printer, and then the ejected ink composition is irradiated with an active energy ray and cured to perform recording.

(Image forming method)
Next, an image forming method suitable for the ink composition of the present invention will be described below.
An image forming method according to the present invention includes an ink application step of applying the above-described ink composition of the present invention onto a recording medium by an ink jet method, and irradiating the applied ink composition with active energy rays to apply the ink composition. And a curing step for curing.

  In the image forming method according to the present invention, it is preferable that the ink composition is heated to 40 ° C. to 80 ° C. to lower the viscosity of the ink composition to 7 mPa · s to 30 mPa · s and then ejected. By using this, high injection stability can be realized. The control range of the ink composition temperature is preferably set temperature ± 5 ° C., more preferably set temperature ± 2 ° C., and still more preferably set temperature ± 1 ° C.

  The ink jet recording apparatus suitable for the image forming method according to the present invention preferably includes means for stabilizing the temperature of the ink composition, and the portion to be maintained at a constant temperature is ejected from an ink tank (an intermediate tank if an intermediate tank is provided). All piping systems and members up to the surface are targeted.

  The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors in each piping portion and perform heating control according to the ink composition flow rate and the environmental temperature. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

  Next, irradiation conditions of active energy rays will be described. A basic irradiation method is disclosed in JP-A-60-132767. Specifically, light sources are provided on both sides of the head unit, and the head and the light sources are scanned by a shuttle method. Irradiation is performed after a certain period of time after ink landing. Further, the curing is completed by another light source that is not driven. In WO99 / 54415, as an irradiation method, a method using an optical fiber or a method in which a collimated light source is applied to a mirror surface provided on the side surface of the head unit to irradiate the recording unit with UV light is disclosed. In the present invention, these irradiation methods can be used.

  In the present invention, the ink composition is heated to a constant temperature, and the time from landing to irradiation is desirably 0.01 seconds to 0.5 seconds, preferably 0.01 seconds to 0.3 seconds. More preferably, the irradiation is performed after 0.01 seconds to 0.15 seconds. Thus, by controlling the time from landing to irradiation to an extremely short time, it is possible to prevent the landing ink from bleeding before being cured. In addition, since the ink composition can be exposed to a porous recording medium before it penetrates deeper than the light source reaches, unreacted monomer residue can be suppressed, and as a result, odor can be reduced. it can. By using the image forming method described above and the ink composition of the present invention in combination, a great synergistic effect is brought about. In particular, when an ink composition having an ink viscosity of 35 MP · s to 500 MP · s at 25 ° C. is used, a great effect can be obtained. By adopting such a recording method, the dot diameter of the landed ink can be kept constant even on various recording media having different surface wettability, and the image quality is improved. In addition, in order to obtain a color image, it is preferable to superimpose in order from the color with the lowest brightness.

  The ink jet recording apparatus that can be used in the image forming method according to the present invention is not particularly limited, and a commercially available ink jet recording apparatus can be used. That is, in the present invention, recording can be performed on a recording medium using a commercially available inkjet recording apparatus.

(recoding media)
The recording medium to which the ink composition of the present invention can be applied is not particularly limited, and various non-absorbent resin materials used for ordinary non-coated paper, coated paper, and so-called soft packaging, or films thereof. A resin film molded into a shape can be used, and examples of various plastic films include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film. In addition, examples of the plastic that can be used as the recording medium material include polycarbonate, acrylic resin, ABS, polyacetal, PVA, and rubbers. Metals and glasses can also be used as a recording medium.

(Printed matter)
The printed matter of the present invention has the recording medium and an image formed on the recording medium with the ink composition. That is, for example, the ink composition is applied to a recording medium by an ink jet printer, and then, preferably, the applied ink composition is cured by irradiation or heating with active energy rays to obtain a printed matter. it can.
The ink composition of the present invention may be used in addition to image formation with ink. In particular, since the ink composition of the present invention is cured by irradiation with energy rays such as ultraviolet rays to obtain a cured film having high strength, for example, the ink composition is formed into an ink receiving layer (image portion) of a lithographic printing plate, etc. May be used for

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the forms in these examples.
Unless otherwise specified, “part” and “%” are based on mass.

  The weight average molecular weight was measured by gel permeation chromatography (GPC). GPC uses HLC-8220GPC (manufactured by Tosoh Corp.), and TSKgeL SuperAWM-H (trade name, manufactured by Tosoh Corp.) is connected in series as a column, and N-methyl is used as an eluent. Pyrrolidone was used. The conditions were as follows: the sample concentration was 0.1% by mass, the flow rate was 0.5 ml / min, the sample injection amount was 10 μl, the measurement temperature was 40 ° C., and the RI detector was used. In addition, the calibration curve is “Standard sample TSK standard, polystyrene” manufactured by Tosoh Corporation: “F-80”, “F-10”, “F-2”, “A-2500”, “A-1000”. Made from 5 samples.

<Preparation of pigment dispersion>
First, Pigment Dispersion 1 was prepared with the following composition.
In the following composition, first, a pigment and a pigment dispersant are added to the acrylate monomer, and the mill base is prepared by stirring with a high speed mixer until uniform, and then the obtained mill base is dispersed for about 1 hour with a horizontal sand mill. Pigment dispersion 1 was prepared.

(composition)
IRGALITE BLUE GLVO (Cyan Pigment, BASF Japan Ltd., surface acid amount: 18.0, surface base amount: 34.0) 27 parts Solsperz 32000 (pigment dispersant, Lubrizol Corporation) 9 parts Phenoxyethyl Acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) 64 parts

<Synthesis Example 1: Synthesis of polymer SP-1 which is (A) polymer according to the present invention>
In a 500 ml three-necked round bottom flask equipped with a condenser and a stirrer, FM-DA11 (diol compound containing a siloxane structure: manufactured by Chisso Corporation, Mn = 1000) 1.0 g (1 mmol), BLEMMER GLM (Japan) Oil and fat Co., Ltd.) 14.4 g (82 mmol), polypropylene glycol (Mw = 3000) (Wako Pure Chemical Industries, Ltd.) 27.00 g (9 mmol) 2-butanone (Wako Pure Chemical Industries, Ltd.) Dissolved in 160 ml). To this, 3.46 g (21 mmol) of 1,6-hexamethylene diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.), 20.62 g (82 mmol) of 4,4-diphenylmethane diisocyanate (manufactured by Aldrich), dibutyl 0.1 g of tin dilaurate (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was heated and stirred at 60 ° C. for 6 hours. Then, it heated to 70 degreeC, 2-butanone (made by Wako Pure Chemical Industries Ltd.) 100ml was added, and also it heated for 2 hours. Furthermore, 50 ml of methyl alcohol was added and stirred for 30 minutes. The reaction solution was poured into 3 liters of hexane with stirring to precipitate a white polymer. The polymer was separated by filtration, washed with water, and dried under vacuum to obtain 65 g of polymer. The specific polyurethane resin synthesized is represented by (SP-1) in Table 1 below.
When the molecular weight was measured by gel permeation chromatography (GPC), the weight average molecular weight (polystyrene standard) was 40000.

<Synthesis Examples 2-5: Synthesis of Polymers SP-2, SP-3, SP-6 and SP-7 which are (A) Polymers of the Present Invention>
The type of monomer used for the synthesis of polymer SP-1 and the amount used thereof were changed to those described in Table 1 below, and SP- 2, SP-3, SP-6 and SP-7 were synthesized. The weight average molecular weight by GPC of the produced polymer was measured in the same manner as SP-1 and was as shown in the structural formula described later.
In Table 1, HDI is 1,6 hexamethylene diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.), MDI is 4,4-diphenylmethane diisocyanate (manufactured by Aldrich), and 1,4-PDI is 1. , 4-phenylene diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.), IPDI is isophorone diisocyanate (manufactured by Wako Pure Chemical Industries, Ltd.), Blemmer GLM (manufactured by NOF Corporation), polypropylene glycol (Wako Pure Chemical Industries, Ltd.) are all commercially available diol compounds. EDA is ethylenediamine (manufactured by Aldrich), which is a commercially available diamine compound.
FM-DA11 (manufactured by Chisso Corp.) is a diol compound containing a siloxane structure marketed under the same name, and 1,2-dodecanediol (manufactured by Aldrich) is a commercial product containing a long-chain alkyl group. The diol compound.

  DF-1 (a diol compound containing a fluorine-substituted hydrocarbon group) is a compound having the following structure, and was synthesized with reference to Journal of Fluorine Chemistry, 1997, 84, 53.

  M-1, M-2, and M-3 (all of which are diol compounds) were synthesized by the following method.

~ Method for synthesizing M-1, M-2, and M-3 ~
2,2-dimethyl-1,3-dioxolane-4-methanol (manufactured by Wako Pure Chemical Industries, Ltd.) as a starting material, Tetrahedron Letters, 1985, 26, 3095, Angelwandte Chemie, 2007, 119, 4229, J Am. Chem. Soc. 2002, 124, 1590, refer to acryloylation, styryl group introduction, vinyl etherification, and then deacetalization using hydrogen chloride (methanol solution) etc. Got. The reaction steps and structures of M-1, M-2, and M-3 are shown below.

<Synthesis Examples 6-7: Synthesis of Polymers SP-4 and SP-5 which are (A) Polymers According to the Present Invention>
(Synthesis of polymer SP-4)
The following components were charged into a three-necked flask having an internal volume of 500 mL and reacted at 75 ° C. for 12 hours with stirring under a nitrogen atmosphere to obtain a polymer solution.

・ Methyl ethyl ketone (MEK) (solvent) 166g
-2- (2-bromoisobutyryloxy) ethyl methacrylate (BBEM, molecular weight 279, manufactured by Manac Co., Ltd.) 19.5 g (0.6 mol)
2- (Perfluorohexyl) ethyl methacrylate (M-1620, molecular weight 432, manufactured by Daikin) (fluorine-substituted hydrocarbon group-containing compound) 43.2 g (0.1 mol)
・ Dimethyl 2,2′-azobis (2-methylpropionate) ((V-601 Wako Pure Chemical Industries, Ltd.), polymerization initiator) 0.345 g

  Further, 100 g of methyl ethyl ketone (MEK), 0.23 g of 4-methoxyphenol, and 50.2 g of 1,8-diazabicyclo [5.4.0] -7-undecene (DBU) were added to the obtained polymer solution, The mixture was neutralized with trifluoromethanesulfonic acid and purified by reprecipitation with water and vacuum drying to obtain polymer SP-4 (61 g) having the following structure. When the molecular weight was measured by gel permeation chromatography (GPC), the weight average molecular weight of the polymer SP-4 was 27000 as a weight average molecular weight (polystyrene standard).

(Synthesis of polymer SP-5)
The following components were charged into an autoclave having an internal volume of 500 L and reacted at 75 ° C. for 12 hours while stirring under a nitrogen atmosphere to obtain a polymer solution.

・ Methyl ethyl ketone (MEK) (solvent) 115g
-2- (2-Bromoisobutyryloxy) ethyl methacrylate (BBEM, Manac Co., Ltd., molecular weight 279) 19.5 g
・ One-end methacrylate-modified dimethyl silicone (manufactured by Chisso Corporation, molecular weight 1000, TM-0701) (compound having a group containing a siloxane structure) 30 g
・ Dimethyl 2,2′-azobis (2-methylpropionate) ((V-601 Wako Pure Chemical Industries, Ltd.), polymerization initiator) 0.345 g

  Further, 100 g of methyl ethyl ketone (MEK) and 35 g of 1,8-diazabicyclo [5.4.0] -7-undecene (DBU) were added to the obtained polymer solution, and the mixture was stirred at room temperature for 12 hours to obtain trifluoromethanesulfone. After neutralization with acid, reprecipitation purification with water and vacuum drying were performed to obtain polymer SP-5 (41 g) having the following structure. When the molecular weight was measured by gel permeation chromatography (GPC), the weight average molecular weight of the polymer SP-5 was 35000 in terms of weight average molecular weight (polystyrene standard).

<Preparation of Silica Fine Particles Having (B) Polymerizable Group According to the Present Invention>
(Preparation of silica fine particles 1 having a polymerizable group)
Silica fine particles 1 having a polymerizable group were prepared as follows according to the method described in JP-A-9-100111.

~ Preparation of organic compounds having radical polymerizable groups and alkoxysilane moieties ~
In a dry air, a solution consisting of 221 parts of mercaptopropyltrimethoxysilane and 1 part of dibutyltin dilaurate is stirred for 1 hour at an internal temperature of 50 ° C. while stirring 223 parts of 1,3-bis (isocyanatomethyl) cyclohexane. After dropping, the mixture was heated and stirred at 70 ° C. for 3 hours. After this was cooled once, 555 parts of pentaerythritol triacrylate was added dropwise at an internal temperature of 30 ° C. over 1 hour, and then heated and stirred at 60 ° C. for 10 hours to obtain a silane compound A. When the amount of residual isocyanate groups in the product was analyzed by gas chromatography, it was 0.1% or less, indicating that the reaction was almost quantitatively completed. In the infrared absorption spectrum of the product, the absorption peak of 2550 Kaiser characteristic of the mercapto group in the raw material and the absorption peak of 2260 Kaiser characteristic of the isocyanate compound of the raw material disappeared. A urethane bond and a 1660 Kaiser peak characteristic of the —S (C═O) NH— group and a 1720 Kaiser peak characteristic of the acryloxy group were observed as polymerizable unsaturated groups. It was shown that an acryloxy group-modified alkoxysilane having both an acryloxy group, -S (C = O) NH-, and a urethane bond, that is, a compound containing a siloxane structure (silane compound A having the following structure) was produced. In the above description, the internal temperature is the liquid temperature of the mixed solution in which the reaction proceeds.

-Preparation of silica fine particles having polymerizable groups-
Under a nitrogen stream, 30 parts of the silane compound A (compound having a radical polymerizable group and an alkoxysilane moiety), MEK-ST (manufactured by Nissan Chemical Co., Ltd., methyl ethyl ketone-dispersed colloidal silica (average particle size 0.01 to 0.00). 015 μm), silica concentration 30%) 233 parts, 5 parts of isopropyl alcohol and 3 parts of ion-exchanged water were stirred at an internal temperature of 80 ° C. for 3 hours, 18 parts of orthoformate methyl ester was added, and 1 By heating and stirring at the same temperature for the time, a dispersion (colorless and transparent) of silica fine particles 1 having a polymerizable group was obtained. In the above description, the internal temperature is the liquid temperature of the mixed solution in which the reaction proceeds.
Further, when added to the ink composition described below, a solution having a solid content of 50% was used by replacing the solvent in which the silica fine particles were dispersed with phenoxyethyl acrylate (PEA). Specifically, after adding 50 g of phenoxyethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) to 50 g of the dispersion of silica fine particles 1, the diluting solvent is distilled off under reduced pressure to prepare a solid concentration of 50%. Used. It was confirmed by ¹ H NMR that the diluting solvent could be distilled off.

(Preparation of silica fine particles 2 having a polymerizable group)
After adding 50 g of phenoxyethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) to 50 g of Desolite Z7501 (manufactured by JSR Corporation), which is a silica fine particle having an acrylate group as a polymerizable group, dilution is performed. The solvent was distilled off under reduced pressure to prepare a solid concentration of 50%, and a phenoxyethyl acrylate solution of silica fine particles 2 having a polymerizable group was obtained. It was confirmed by ¹ H NMR that the diluting solvent could be distilled off.

<Example 1>
(Preparation of ink composition)
Using the prepared pigment dispersion 1, necessary components were further appropriately added and mixed with stirring for 2 hours so that each component had the following ratio. After stirring and mixing, it was confirmed that there was no dissolved residue, filtered through a membrane filter, and coarse particles were removed, whereby the ink composition of Example 1 was obtained. The viscosity of the ink composition at the ink discharge temperature (45 ° C.) was in the range of 20 mPa · s.

・ IRGALITE BLUE GLVO
(Cyan pigment: BASF Japan) 2.7%
・ Solspers 32000 (pigment dispersant: manufactured by Lubrizol) 0.9%
・ Lucirin TPO (Polymerization initiator: BASF Japan) 8.0%
・ Benzophenone (Polymerization initiator: BASF Japan) 3.4%
・ Irgacure 184 (polymerization initiator: BASF Japan) 2.0%
-N-vinylcaprolactam (NVC Aldrich) 38.0%
・ 2-phenoxyethyl acrylate
(PEA: manufactured by Tokyo Chemical Industry Co., Ltd.) 38.0%
(However, PEA derived from silica fine particles 1 having the following polymerizable group is included)
-Polymer SP-1 (component (A)) 2.0%
-Silica fine particles 1 having the polymerizable group
(50% solution of PEA) (component (B)) 5.0% in terms of solid content

<Examples 2 to 15>
(Preparation of ink compositions of Examples 2 to 15)
Ink compositions of Examples 2 to 15 were prepared in the same manner as in Example 1 except that each component in the preparation of the ink composition of Example 1 was changed as shown in Table 2 below.

<Comparative Example 1>
(Preparation of ink composition of Comparative Example 1)
An ink composition of Comparative Example 1 was prepared in the same manner as in Example 1 except that silica fine particles 1 having a polymerizable group were not added and (C) other polymerizable compounds were increased as shown in Table 2. .

<Comparative example 2>
(Preparation of ink composition of Comparative Example 2)
An ink composition of Comparative Example 2 was prepared in the same manner as in Example 1 except that the polymer SP-1 was not added and the amount of the silica fine particles having a polymerizable group was increased as shown in Table 2.

<Comparative Example 3>
(Preparation of ink composition of Comparative Example 3)
As shown in Table 2, an ink composition of Comparative Example 3 was prepared in the same manner as in Example 1 except that the amount of the silica fine particles 1 having a polymerizable group was increased and (C) the other polymerizable compound was reduced. .

<Evaluation of ink composition>
(Image recording)
First, each prepared ink composition was filtered with a filter having an absolute filtration accuracy of 2 μm.
Inkjet images were recorded using a UV curable ink inkjet printer LUXELJET UV250 (manufactured by Fuji Film Graphic Systems). A 100% solid image was printed at a resolution of 600 × 450 dpi on various recording media. The apparatus performs drawing by operating an ink jet head, and one UV lamp is mounted on each end of the head, and two UV lamps are irradiated by one head operation. It has a form like this. The solid image was formed by alternately repeating ink droplets and UV irradiation by two lamps at the same location on the support 8 times. The lamp was equipped with SUB ZERO 085 H bulb lamp unit manufactured by Integration Technology, and the lamp intensity at the front and rear was set to level 3. When the road surface illuminance was measured during printing, it was 980 mW / cm ² . The time from ejection to exposure was 0.2 to 0.3 seconds. The discharge amount per drop was in the range of 6 to 42 pL. Moreover, the recording medium was selected according to each evaluation mentioned later.

  Under these conditions, the hardness, suitability for drilling, and flexibility of the image formed using the ink composition were evaluated by the following methods. The evaluation results are shown in Table 3 below.

(Evaluation of hardness)
Using a polycarbonate (PC) substrate (size: 10 cm × 10 cm, thickness: 500 μm) as a recording medium, an image was formed according to the above-described image recording. The obtained image part was evaluated according to the method described in JIS K5600-5-4. The evaluation criteria are as follows.

~Evaluation criteria~
5: 2H or more 4: H or more and less than 2H 3: F or more but less than H 2: HB or more but less than F 1: less than HB * 4 to 5 are practically no problem.

(Evaluation of drilling suitability)
A polycarbonate (PC) substrate (size: 10 cm × 10 cm, thickness: 500 μm) was used as a recording medium, and 20 images were prepared according to the above-described image recording. The obtained image part was punched out with a punch (Kokuyo Co., Ltd .: PN83NB), and the number of cracks around the hole was visually examined. The evaluation criteria are as follows.

~Evaluation criteria~
5: In all samples, cracks were not present 4: Cracks were observed in 1-2 samples 3: Cracks were observed in 3-4 samples 2: Cracks were observed in 5-9 samples 1: Cracks in more than 10 samples * 4-5 are practically no problem.

(Evaluation of flexibility)
Images were formed according to the above-mentioned image recording using Fasson PE (Fasson polyethylene film: film thickness 100 μm) as a recording medium. The recording medium on which the image area is formed is cut into an axial length of 5 cm and a width of 2.5 cm, and stretched at a speed of 30 cm / min using a tensile tester (manufactured by Shimadzu Corporation, Autograph AGS-J). The elongation at which the (cured film) breaks was measured. The state of elongation from the initial length to twice the length was defined as 100% elongation.

~Evaluation criteria~
5: Stretching rate of 300% or more 4: Stretching rate of 200% or more and less than 300% 3: Stretching rate of 150% or more and less than 200% 2: Stretching rate of 100% or more and less than 150% 1: Stretching rate of less than 100% * 4 to 5 are practical Above, there is no problem.

As is apparent from Table 3, the ink composition of the present invention can achieve both the hardness and flexibility of the image area in a favorable range, has high drilling suitability, and has a higher stress such as drilling. Even if is added, cracks in the image portion can be suppressed.

Claims (11)

(A) Polymer having a polymerizable group in the side chain, and (a1) a fluorine-substituted hydrocarbon group, (a2) a group containing a siloxane structure, and (a3) a long-chain alkyl group When,
(B) silica fine particles having a polymerizable group;
(C) The polymerizable compound other than (A) and (B),
(D) a polymerization initiator;
Including
0.1 mass%-30 mass% of said (B) silica fine particles are included with respect to the total content (TX) of said (A) polymer, said (B) silica fine particles, and said (C) polymeric compound. An ink composition characterized by the above.   The ink composition according to claim 1, wherein the polymerizable group of the polymer (A) is a (meth) acrylic acid ester group.   3. The ink composition according to claim 1, wherein the polymerizable group of the (B) silica fine particles is a (meth) acrylic acid ester group. 4.   The ink composition according to any one of claims 1 to 3, wherein the polymer (A) is contained in an amount of 0.2% by mass to 10% by mass with respect to the total content (TX). .  5. The ink composition according to claim 1, wherein the content of the monofunctional monomer in the polymerizable compound (C) is 60% by mass to 100% by mass.   The ink composition according to any one of claims 1 to 5, wherein the polymer (A) contains a urethane structure or a urea structure as a main chain structure.   The ink composition according to claim 1, wherein the (A) polymer contains a (meth) acrylate structure as a main chain structure.   The ink composition according to any one of claims 1 to 7, further comprising (E) a colorant.   The ink composition according to any one of claims 1 to 8, wherein the ink composition is for inkjet recording.   An image forming method comprising an ink application step of applying the ink composition according to any one of claims 1 to 9 onto a recording medium by an inkjet method. A printed matter obtained by the image forming method according to claim 10.