JP2022024838A - Clear ink composition, ink set, and recording method - Google Patents

Abstract

To provide a clear ink composition for improving the scratch resistance of a coating layer with respect to a wide range of recording media from a polar recording medium to a low polar recording medium.SOLUTION: The present invention discloses a water-based clear ink composition containing a resin, where the resin contains a urethane resin (U) having a structure derived from an active hydrogen component (A) containing a polymer polyol component (a1) with a number average molecular weight of 500 or more and an organic polyisocyanate component (B), and the polymer polyol component (a1) has a predetermined constitutional unit.SELECTED DRAWING: None

Description

The present invention relates to a clear ink composition, an ink set, and a recording method.

The inkjet recording method is a relatively simple device that can record high-definition images, and is rapidly developing in various fields. Among them, various studies have been made on image quality, ejection stability, and the like. For example, Patent Document 1 provides an ink composition or the like which is excellent in abrasion resistance and can obtain sufficient glossiness even when glossiness of a film or the like is required while satisfying intermittent ejection stability. An ink composition using a predetermined urethane resin is disclosed for the purpose of.

Japanese Unexamined Patent Publication No. 2019-81826

There are various recording media for recording with ink. When recording with different inks for various recording media, it is necessary to change the inks. It is desired that recording can be performed on various recording media using the same ink, but when the same ink is used, there is a problem that quality such as abrasion resistance cannot be obtained depending on the characteristics of the recording medium.

When an attempt is made to record using the same ink composition on recording media having such different characteristics, the adhesion between the recording medium and the ink composition differs due to the difference in the characteristics, and the obtained recorded material has, for example, scratch resistance. Will give different results. Therefore, there is a demand for an ink composition that can provide a recording material having excellent abrasion resistance even when used for recording media having different characteristics.

（式（１）中、Ｒ¹は水素原子、メチル基、エチル基、ビニル基、イソプロピル基又はイソプロペニル基を表し、Ｒ²は水素原子又はメチル基を表す。）

（式（２）中、Ｒ³は水素原子又はメチル基を表す。）

The clear ink composition of the present invention is an aqueous clear ink composition containing a resin, wherein the resin contains an active hydrogen component (A) containing a polymer polyol component (a1) having a number average molecular weight of 500 or more. , The organic polyisocyanate component (B) and the urethane resin (U) having a composition derived from the polymer polyol component (a1) are the structural units represented by the general formula (1) and / or the general formula (. It has a structural unit represented by 2) and a structural unit represented by the general formula (3).

(In the formula (1), R ¹ represents a hydrogen atom, a methyl group, an ethyl group, a vinyl group, an isopropyl group or an isopropenyl group, and R ² represents a hydrogen atom or a methyl group.)

(In formula (2), R ³ represents a hydrogen atom or a methyl group.)

Further, the ink set of the present invention includes the above-mentioned clear ink composition and a water-based colored ink composition containing a coloring material.

Further, the recording method of the present invention includes a clear ink adhering step of adhering the clear ink composition to a recording medium.

It is a schematic side view which shows an example of the recording apparatus which can be used in this embodiment.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiments”) will be described in detail with reference to the drawings as necessary, but the present invention is not limited thereto and is a gist thereof. Various deformations are possible within the range that does not deviate from. In the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. In addition, the positional relationship such as up, down, left, and right shall be based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the ratios shown.

1. 1. Clear Ink Composition The clear ink composition of the present embodiment is an aqueous clear ink composition containing a resin, in which the resin contains a polymer polyol component (a1) having a number average molecular weight of 500 or more. The polymer polyol component (a1) contains a urethane resin (U) having a composition derived from the component (A) and the organic polyisocyanate component (B), and the structural unit represented by the general formula (1) and / Or has a structural unit represented by the general formula (2) and a structural unit represented by the general formula (3).

（式（１）中、Ｒ¹は水素原子、メチル基、エチル基、ビニル基、イソプロピル基又はイソプロペニル基を表し、Ｒ²は水素原子又はメチル基を表す。）

(In the formula (1), R ¹ represents a hydrogen atom, a methyl group, an ethyl group, a vinyl group, an isopropyl group or an isopropenyl group, and R ² represents a hydrogen atom or a methyl group.)

（式（２）中、Ｒ³は水素原子又はメチル基を表す。）

(In formula (2), R ³ represents a hydrogen atom or a methyl group.)

The recording medium for recording is not limited, but for example, when a low-absorbency recording medium or a non-absorbent recording medium is used, it is preferable that the recording medium has excellent water resistance and the like. Of these, a non-absorbent recording medium is preferable, and a film-based recording medium is preferable.

For example, as a film for flexible packaging printing, biaxially stretched polypropylene film (hereinafter, also referred to as OPP) and polyethylene terephthalate (hereinafter, also referred to as PET) are widely used. A flexible film typified by OPP is used, for example, in a bag of bread, and a film having elasticity typified by PET is used, for example, as a lid of a tofu pack.

Film-based recording media include polar recording media having many polar groups such as PET and nylon, and low-polarity recording media having few polar groups such as OPP.

As described above, even as a film for flexible packaging printing, a film having different characteristics depending on the application is used, from a film having a low polarity such as OPP to a film having a high polarity such as PET.

When recording is performed using the same ink composition for films having such different characteristics, the adhesion between the film and the ink composition differs due to the difference in polarity, and the scratch resistance of the obtained recorded material differs. Will be.

In general, an ink composition containing a fixing component having a high affinity for a polar recording medium exhibits high scratch resistance to a polar recording medium, and an ink composition containing a fixing component having a high affinity for a low polarity recording medium is used. , Shows high abrasion resistance against low-polarity recording media. Therefore, it has been difficult to develop an ink composition having contradictory properties such that it exhibits high abrasion resistance for both polar recording media and low-polarity recording media.

On the other hand, in the present embodiment, by using the urethane resin (U) having the above structure as a component for improving the adhesion, it is excellent for a wide range of recording media from polar recording media to low-polarity recording media. Abrasion resistance can be achieved. In particular, according to the present embodiment, the rubbing resistance includes the rubbing resistance in a dry state (hereinafter, also referred to as “dry rubbing resistance”) and the rubbing resistance in a wet state (hereinafter, also referred to as “wet rubbing resistance”). Any of these can be improved. In the following, dry rubbing resistance and wet rubbing resistance are not particularly distinguished, and when either or both are referred to, it is simply referred to as "rubbing resistance".

Hereinafter, each component of the clear ink composition of the present embodiment will be described in detail. In the present embodiment, the "clear ink" is not an ink composition intended to color a recording medium, but an ink used for other purposes. Other purposes are to adjust the glossiness of the recording medium, improve characteristics such as scratch resistance of the recorded material, and improve the fixability and color development of the colored ink composition. Therefore, it is preferable that the clear ink does not contain the coloring material in an amount of more than 0.1% by mass (the content is 0.1% by mass or less), and more preferably it does not contain more than 0.05% by mass. , 0.01% by mass is more preferable, and it is particularly preferable that the coloring material is not contained (content is 0% by mass).

In particular, by incorporating the urethane resin (U) in the clear ink composition instead of the colored ink composition used for the purpose of including the coloring material and coloring, clogging due to the coexistence of the coloring material and the urethane resin (U), etc. It is possible to impart high abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media. The reason why clogging is likely to occur by coexisting the coloring material and the urethane resin (U) is not particularly limited, but the urethane resin (U) used for the purpose of improving the abrasion resistance has relatively high hydrophobicity. It is considered that the design is not good in compatibility with the pigment or the pigment dispersion, and clogging or the like is likely to occur.

1.1. Resin The clear ink composition of the present embodiment contains the above-mentioned urethane resin (U) as a resin, and if necessary, contains a urethane resin (F) described later and a urethane resin (A) described later. It may also contain resins other than these. Hereinafter, each resin will be described.

1.1.1. Urethane resin (U)
The urethane resin (U) has a structure derived from an active hydrogen component (A) containing a polymer polyol component (a1) having a number average molecular weight of 500 or more and an organic polyisocyanate component (B), and has a high content. The molecular polyol component (a1) has a structural unit represented by the general formula (1) and / or a structural unit represented by the general formula (2) and a structural unit represented by the general formula (3). It is a thing.

Such a urethane resin (U) is at least a polymer in which the polymer polyol component (a1) and the organic polyisocyanate component (B) are bonded by a urethane bond, and is represented by the general formula (1). The structural unit and / or the structural unit represented by the general formula (2) and the structural unit represented by the general formula (3) are included.

The urethane resin (U) is preferably added to the ink composition as an aqueous dispersion, and the urethane resin (U) is preferably dispersed as resin fine particles in the clear ink composition.

The content of the urethane resin (U) is preferably 1% by mass or more with respect to the total amount of the clear ink composition. Further, it is preferably 2 to 20% by mass, more preferably 2.5 to 15% by mass, and further preferably 3.0 to 12% by mass. When the content of the urethane resin (U) is within the above range, the abrasion resistance of the coating film is further improved and the clogging recovery property is improved for a wide range of recording media from polar recording media to low-polarity recording media. It tends to be good. When the urethane resin (U) is used in a dispersion described later, the above-mentioned content means the solid content thereof.

When the clear ink composition contains the urethane resin (A) described later, the content of the urethane resin (U) with respect to the total amount of the clear ink composition is the content of the urethane resin (A) with respect to the total amount of the clear ink composition. The above is preferable. The content of the urethane resin (U) is preferably 105 to 200 parts by mass, more preferably 110 to 160 parts by mass, and further preferably 110 to 140 parts by mass with respect to 100 parts by mass of the urethane resin (A). It is a department. When the content of the urethane resin (U) is within the above range, the abrasion resistance of the coating film tends to be further improved for a wide range of recording media from polar recording media to low-polarity recording media.

The content of the urethane resin (U) is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, and the upper limit is 100% by mass, based on the total mass of the total urethane resin contained in the ink. It may be less than or equal to 90% by mass, preferably 70% by mass or less. In the above range, scratch resistance, clogging recovery, and the like are more excellent and preferable.

1.1.1.1. Active hydrogen component (A)
The active hydrogen component (A) contains a high molecular weight polyol component (a1), and if necessary, a low molecular weight polyol component (a2) having no ionic group or a low molecular weight polyol component (a2) having a number average molecular weight of less than 500, and an ionic group. A compound (a3) containing an active hydrogen atom, a chain extender (a4) other than the low molecular weight polyol component (a2), and a reaction terminator (a5) may be contained. Among these, it is preferable to contain the small molecule polyol component (a2) and / or the compound (a3) in addition to the high molecular weight polyol component (a1).

1.1.1.1.1. Polymer polyol component (a1)
The polymer polyol component (a1) used for the polymerization of the urethane resin (U) has a structural unit represented by the general formula (1) and / or a structural unit represented by the general formula (2), and has a number average molecular weight. A polyester polyol (hereinafter, may be abbreviated as "Mn") having 500 or more polyolefin polyols (a11) and a structural unit represented by the general formula (3) and having a number average molecular weight of 500 or more (hereinafter, may be abbreviated as "Mn"). It may contain a12) and, if necessary, another polyol (a13).

In the urethane resin (U), the configuration derived from the polyolefin polyol (a11) becomes a portion having a relatively high affinity for the low-polarity recording medium, and the configuration derived from the polyester polyol (a12) becomes the polar recording medium. On the other hand, it is a part having a relatively high affinity. Therefore, since the urethane resin (U) contains both a structure derived from the polyolefin polyol (a11) and a structure derived from the polyester polyol (a12), the urethane resin (U) can be used from a polar recording medium to a low-polarity recording medium. It can exhibit high abrasion resistance against a wide range of recording media.

一般式（１）におけるＲ¹は水素原子、メチル基、エチル基、ビニル基、イソプロピル基又はイソプロペニル基を表し、Ｒ²は水素原子又はメチル基を表す。尚、ポリオレフィンポリオール（ａ１１）中に連続する３個以上のメチレン基がある場合、一般式（１）におけるＲ¹及びＲ²が水素原子である構成単位（エチレン基）が存在するものと解釈する。

In the general formula (1), R ¹ represents a hydrogen atom, a methyl group, an ethyl group, a vinyl group, an isopropyl group or an isopropenyl group, and R ² represents a hydrogen atom or a methyl group. When the polyolefin polyol (a11) contains three or more consecutive methylene groups, it is interpreted that there is a structural unit (ethylene group) in which R ¹ and R ² in the general formula (1) are hydrogen atoms. ..

式（２）中、Ｒ³は水素原子又はメチル基を表す。

In formula (2), R ³ represents a hydrogen atom or a methyl group.

The content of the composition derived from the polyolefin polyol (a11) is preferably 15 to 55% by mass, more preferably 20 to 50% by mass, and further preferably 30 with respect to the total amount of the urethane resin (U). ~ 50% by mass. The content of the composition derived from the polyester polyol (a12) is preferably 4 to 40% by mass, more preferably 7 to 30% by mass, still more preferably, based on the total amount of the urethane resin (U). Is 10 to 25% by mass. When the content of the composition derived from the polyolefin polyol (a11) and the content of the composition derived from the polyester polyol (a12) are within the above ranges, it can be applied to a wide range of recording media from polar recording media to low-polarity recording media. The abrasion resistance of the coating film tends to improve.

The Mn of each polyol contained in the polymer polyol component (a1) is preferably 500 or more, more preferably 500 to 6000, and further preferably 1000 to 4000. When the Mn of each polyol is within the above range, the abrasion resistance, flexibility and mechanical properties of the coating film tend to be further improved for a wide range of recording media from polar recording media to low-polarity recording media. The Mn of each polyol can be measured by gel permeation chromatography, for example, under the following conditions.
-Device: "Waters Alliance 2695" [manufactured by Waters] Column: "Guardcolum SuperH-L" (1), "TSKgel SuperH2000, TSKgel SuperH3000, TSKgel SuperH4000 (all manufactured by Tosoh Corporation) thing"
-Sample solution: 0.25 mass% tetrahydrofuran solution-Solution injection amount: 10 μl
・ Flow rate: 0.6 ml / min ・ Measurement temperature: 40 ° C
・ Detection device: Refractive index detector ・ Reference material: Standard polyethylene glycol

1.1.1.1.1.1.1. Polyolefin polyol (a11)
The polyolefin polyol (a11) is not particularly limited, and for example, polybutadiene polyols, hydrogenated polybutadiene polyols, polyisoprene polyols, hydrogenated polyisoprene polyols, and polyolefins described in, for example, Japanese Patent Laid-Open No. 2018-0764428 are unsaturated (poly). ) Examples thereof include hydroxyl group-modified polyolefins that can be obtained by reacting an acid-modified polyolefin modified with a carboxylic acid (anhydride) with an amino alcohol. The polyolefin polyol (a11) may be used alone or in combination of two or more.

Commercially available products of the polyolefin polyol (a11) include, for example, NISSO-PBG series [polybutadiene polyol, manufactured by Nippon Soda Co., Ltd.], Poly bd series [polybutadiene polyol, manufactured by Idemitsu Kosan Co., Ltd.], NISSO-PB GI series [ Water-added polybutadiene polyol, manufactured by Nippon Soda Co., Ltd.], Polytail H [water-added polybutadiene polyol, manufactured by Mitsubishi Chemical Co., Ltd.], Poly ip series [polyisoprene polyol, manufactured by Idemitsu Kosan Co., Ltd.], EPOL series [water-added Polyisoprene polyol, manufactured by Idemitsu Kosan Co., Ltd.] and the like.

Among the polyolefin polyols (a11), a structural unit represented by the general formula (1) is preferable from the viewpoint of adhesion and abrasion resistance of the urethane resin (U) to a low-polarity substrate such as OPP. Polyolefin polyols, more preferred are polyolefin polyols having the following structural units (i) and / or (ii), and polyolefin polyols having the following structural units (iii) and (iv), with particular preference being the following structural units (i). ) And / or a polyolefin polyol having (ii), most preferably a hydrogenated polybutadiene polyol.
-Structural unit (i): R ¹ in the general formula (1) is an ethyl group and R ² is a hydrogen atom-Structural unit (ii): R ¹ in the general formula (1) is a hydrogen atom and R ² is A structural unit / structural unit (iii) in which two structural units that are hydrogen atoms are connected: A structural unit / structural unit (iv) in which R ¹ is a vinyl group and R ² is a hydrogen atom in the general formula (1): general. A building block in which R ³ in equation (2) is a hydrogen atom

1.1.1.1.1.2. Polyester polyol (a12)
The polyester polyol (a12) is not particularly limited, and is, for example, a polyester polyol obtained by dehydration condensation of terephthalic acid and a polyhydric alcohol having 2 to 20 carbon atoms, and 4 to 20 carbon atoms other than terephthalic acid and terephthalic acid. Examples thereof include polyester polyols obtained by dehydration condensation of a polyhydric carboxylic acid or an ester-forming derivative thereof and a polyhydric alcohol having 2 to 20 carbon atoms. The polyester polyol (a12) may be used alone or in combination of two or more.

As the polyhydric alcohol having 2 to 20 carbon atoms, a linear diol having 2 to 12 carbon atoms or an aliphatic diol having 3 to 12 carbon atoms having a branch [ethylene glycol, 1,3-propylene glycol, 1,4-butane] Diol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-dodecanediol, diethylene glycol, triethylene glycol and Linear alcohols such as tetraethylene glycol; 1,2-propylene glycol, 1,2-, 1,3- or 2,3-butanediol, 2-methyl-1,4-butanediol, neopentyl glycol, 2, 2-diethyl-1,3-propanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,6-hexanediol, 3-methyl-1, 6-hexanediol, 2-methyl-1,7-heptanediol, 3-methyl-1,7-heptanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 3 -Branch alcohols such as methyl-1,8-octanediol and 4-methyloctanediol]; alicyclic diols with 6 to 20 carbon atoms [1,4-cyclohexanediol, 1,3-cyclohexanedimethanol, 1, 4-Cyclohexanediol, 1,3-cyclopentanediol, 1,4-cycloheptanediol, 2,5-bis (hydroxymethyl) -1,4-dioxane, 2,7-norbornandiol, tetrahydrofuran dimethanol, 1, 4-Bis (hydroxyethoxy) cyclohexane, 1,4-bis (hydroxymethyl) cyclohexane and 2,2-bis (4-hydroxycyclohexyl) propane, etc.]; Aromatic ring-containing diols with 8 to 20 carbon atoms [m- or p. -Xylylene glycol, bis (hydroxyethyl) benzene and bis (hydroxyethoxy) benzene, etc.]; Triols with 3 to 20 carbon atoms [Alipid triols (glycerin, trimethylolpropane, etc.), etc.]; 4 with 5 to 20 carbon atoms Examples thereof include aliphatic alcohols [aliphatic polyols (pentaerythritol, sorbitol, mannitol, sorbitan, diglycerin, dipentaerythritol, etc.); sugars (sucrose, glucose, mannose, fructose, methylglucoside and derivatives thereof)] and the like.

Among these, an aliphatic diol having a branch and having 3 to 12 carbon atoms is preferable. By using the polyester polyol (a12) obtained by using such a polyhydric alcohol, it has high abrasion resistance against a wide range of recording media from polar recording media to low-polarity recording media, and the flexibility of the coating film. And the mechanical properties tend to be improved.

Examples of polyvalent carboxylic acids having 4 to 20 carbon atoms other than terephthalic acid or ester-forming derivatives thereof include aliphatic dicarboxylic acids (succinic acid, adipic acid, azelaic acid, sebatic acid, fumaric acid, maleic acid, etc.) and alicyclic. Formula Dicarboxylic acid (Dymer acid, etc.), aromatic dicarboxylic acid excluding terephthalic acid (phthalic acid, isophthalic acid, etc.), trivalent or higher polycarboxylic acid (trimellitic acid, pyromellitic acid, etc.), anhydrides thereof. (Succinic acid anhydride, maleic acid anhydride, phthalic acid anhydride, trimellitic acid anhydride, etc.), their acid halides (dichloride adipic acid, etc.), these low molecular weight alkyl esters (dimethyl succinate, dimethyl phthalate, etc.), and these. Examples include the mixture of. Among these, aliphatic dicarboxylic acids and ester-forming derivatives thereof are preferable. By using the polyester polyol (a12) obtained by using such a polyvalent carboxylic acid or the like, it has high abrasion resistance against a wide range of recording media from polar recording media to low-polarity recording media, and the coating film has high abrasion resistance. Flexibility and mechanical properties tend to be improved.

1.1.1.1.1.1.3. Other polyol (a13)
The other polyol (a13) is not particularly limited, but for example, a polyester polyol (a131) having a number average molecular weight of 500 or more and having no structural unit represented by the general formula (3), and the general formula (1). Examples thereof include a polyether polyol (a132) having a number average molecular weight of 500 or more and having no structural unit represented by the above and the structural unit represented by the general formula (2). As the other polyol (a13), one type may be used alone or two or more types may be used in combination.

Examples of the polyester polyol (a131) include condensed polyester polyols, polylactone polyols, polycarbonate diols, castor oil-based polyols, and the like, in addition to the polyester polyol (a12).

The condensed polyester polyol is a polyester obtained by dehydration condensation of the above-mentioned polyhydric alcohol having 2 to 20 carbon atoms and a polyvalent carboxylic acid having 4 to 20 carbon atoms other than terephthalic acid or an ester-forming derivative thereof. Examples include polyols.

Commercially available condensed polyester polyols include Sun Ester 2610 [Mn = 1000 polyethylene adipatediol, Sanyo Kasei Kogyo Co., Ltd.] and Sun Esther 4620 [Mn = 2000 polytetramethylene] manufactured by Sanyo Kasei Kogyo Co., Ltd. Adipatediol], Sun Esther 2620 [Mn = 2000 polyethylene adipatediol]; Clare polyol P-2010 [Mn = 2000 poly-3-methyl-1,5-pentaneadipatediol], Clare polyol Examples include P-3010 [Mn = 3000 poly-3-methyl-1,5-pentaneadipatediol] and Clare polyol P-6010 [Mn = 6000 poly-3-methyl-1,5-pentaneadipatediol]. Be done.

Examples of the polylactone polyol include the above-mentioned heavy adduct of lactone to a polyhydric alcohol having 2 to 20 carbon atoms. Examples of the lactone include lactones having 4 to 12 carbon atoms (for example, γ-butyrolactone, γ-valerolactone and ε-caprolactone). Specific examples of the polylactone polyol include polycaprolactone diol, polyvalerolactone diol, polycaprolactone triol and the like.

Examples of the polycarbonate diol include a polycarbonate polyol produced by condensing the above-mentioned polyhydric alcohol having 2 to 20 carbon atoms and a low molecular weight carbonate compound while performing a dealcohol reaction. Examples of the low molecular weight carbonate compound include a dialkyl carbonate having an alkyl group having 1 to 6 carbon atoms, an alkylene carbonate having an alkylene group having 2 to 6 carbon atoms, and a diaryl carbonate having an aryl group having 6 to 9 carbon atoms.

Commercially available products of polycarbonate diol include Duranol T6002 [Mn = 2000 polycarbonate diol using 1,6-hexanediol, manufactured by Asahi Kasei Chemicals Co., Ltd.] and Duranol G4672 [1,4-butane] manufactured by Asahi Kasei Chemicals Co., Ltd. Diol / 1,6-hexanediol = 70/30 (molar ratio) of Mn = 2000 polycarbonate diol], Duranol T5652 [1,5-pentanediol / 1,6-hexanediol = 50/50 (molar) Mn = 2000 polycarbonate diol using ratio)]; ETERNACOLL UH-300 [Mn = 3000 polycarbonate diol using 1,6-hexanediol], ETERNACOLL UM-90 (1 /) manufactured by Ube Kosan Co., Ltd. 3) [Polycarbonate diol of Mn = 900 using 1,4-cyclohexanedimethanol / 1,6-hexanediol = 1/3 (molar ratio)]; Mn = 2000 polycarbonate diol using methyl-1,5-pentanediol / 1,6-hexanediol = 90/10 (molar ratio)], Clare polyol C-2050 [3-methyl-1,5-pentanediol / 1,6-Hexanediol = 50/50 (molar ratio) of Mn = 2000 polycarbonate diol] and the like.

The castor oil-based polyol includes castor oil and a modified castor oil modified with a polyol or an alkylene oxide having 2 to 12 carbon atoms (hereinafter, abbreviated as AO). The modified castor oil can be produced by transesterification of castor oil and a polyol and / or addition of AO. Examples of the castor oil-based polyol include castor oil, trimethylolpropane-modified castor oil, pentaerythritol-modified castor oil, and ethylene oxide (hereinafter abbreviated as EO) adducts (additional moles: 4 to 30 mol) of castor oil. ..

Examples of AO having 2 to 12 carbon atoms include EO, propylene oxide (hereinafter abbreviated as PO), 1,2-, 2,3- or 1,3-butylene oxide, tetrahydrofuran, 3-methyltetrahydrofuran, and α-olefin oxide. , Styrene oxide, epichlorohydrin (epicchlorohydrin, etc.) and the like.

Examples of the polyether polyol (a132) include aliphatic polyether polyols and aromatic polyether polyols.

Examples of the aliphatic polyether polyol include an AO adduct having 2 to 12 carbon atoms to an aliphatic polyhydric alcohol having 2 to 20 carbon atoms, and specifically, a polyoxyalkylene polyol (polyethylene glycol or the like). Examples thereof include polyoxypropylene polyol (polypropylene glycol and the like), polyoxyethylene / propylene polyol and polytetramethylene ether glycol.

Commercially available aliphatic polyether polyols include PTMG1000 [Mn = 1000 poly (oxytetramethylene) glycol], PTMG2000 [Mn = 2000 poly (oxytetramethylene) glycol], and PTMG3000 [Mn = 1000 poly (oxytetramethylene) glycol] manufactured by Mitsubishi Chemical Corporation. Mn = 3000 poly (oxytetramethylene) glycol]; PTGL2000 [Mn = 2000 modified poly (oxytetramethylene) glycol] manufactured by Hodoya Chemical Industry Co., Ltd., PTGL3000 [Mn = 3000 modified poly (oxytetramethylene) glycol] ) Glycol], Sanniks PP-2000 [Mn = 2000 polyoxypropylene glycol] and Sanniks Diol GP-3000 [Mn = 3000 polyoxypropylene triol] manufactured by Sanyo Kasei Kogyo Co., Ltd., manufactured by Ebonic Degusa. TEGOMER D3403 [Mn = 1,200 polyoxyethylene polyol,]; Ymer N120 manufactured by Perstoop [Mn = 1,000 polyoxyethylene polyol] and the like can be mentioned.

The aromatic polyether polyol is not particularly limited, and is, for example, an EO adduct of bisphenol A (EO 2 mol adduct of bisphenol A, EO 4 mol adduct of bisphenol A, EO 6 mol adduct of bisphenol A, bisphenol A). EO 8 mol adduct, EO 10 mol adduct of bisphenol A, EO 20 mol adduct of bisphenol A, etc.) and PO adduct of bisphenol A (PO 2 mol adduct of bisphenol A, PO 3 mol adduct of bisphenol A and PO5 of bisphenol A) Examples thereof include polyols having a bisphenol skeleton such as molar adducts) and EO or PO adducts of resorcin.

1.1.1.1.2. Small molecule polyol component (a2)
The small molecule polyol component (a2) is not particularly limited as long as it is a small molecule polyol having no ionic group and having a chemical formula or a number average molecular weight of less than 500. For example, the above-mentioned polyhydric alcohol having 2 to 20 carbon atoms is described above. Can be mentioned. The small molecule polyol component (a2) may be used alone or in combination of two or more.

Among these, linear diols having 2 to 12 carbon atoms or aliphatic diols having 3 to 12 carbon atoms having branches are preferable, and aliphatic diols having 3 to 12 carbon atoms having branches are more preferable, 1,3-butane. More preferred are diols or neopentyl glycols. By using such a small molecule polyol component (a2), the abrasion resistance to a wide range of recording media from polar recording media to low polar recording media tends to be further improved, and the flexibility and mechanical characteristics of the coating film tend to be further improved. be.

1.1.1.1.3. Compound (a3)
The compound (a3) is not particularly limited as long as it is a compound containing an ionic group and an active hydrogen atom, and is, for example, a compound (a31) containing an anionic group and an active hydrogen atom, and a cationic group and an active hydrogen atom. The compound (a32) containing the above can be mentioned. The compound (a3) may be used alone or in combination of two or more.

11.1.1.3.1. Compound (a31)
The compound (a31) is, for example, a compound containing a carboxyl group as an anionic group and having 2 to 10 carbon atoms [dialkylol alkanoic acid (for example, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutane). Acids, 2,2-dimethylol heptanic acid and 2,2-dimethylol octanoic acid), tartaric acid and amino acids (eg glycine, alanine and valine)], containing a sulfonic acid group as an anionic group and having 2 carbon atoms. It contains ~ 16 compounds [3- (2,3-dihydroxypropoxy) -1-propanesulfonic acid, sulfoisophthalic acid di (ethylene glycol) ester, etc.], a sulfamic acid group as an anionic group, and has 2 to 2 to carbon atoms. Examples thereof include 10 compounds [N, N-bis (2-hydroxylethyl) sulfamic acid, etc.] and salts obtained by neutralizing these compounds with a neutralizing agent. Among these, a compound having two or more hydroxyl groups is preferable, and dialkylol alkanoic acid is more preferable. The compound (a31) may be used alone or in combination of two or more.

Examples of the neutralizing agent used for the salt of the compound (a31) include ammonia, an amine compound having 1 to 20 carbon atoms, or an alkali metal hydroxide (sodium hydroxide, potassium hydroxide, lithium hydroxide, etc.).

Examples of the amine compound having 1 to 20 carbon atoms include primary amines such as monomethylamine, monoethylamine, monobutylamine and monoethanolamine, and secondary amines such as dimethylamine, diethylamine, dibutylamine, diethanolamine and diisopropanolamine and methylpropanolamine. Examples thereof include amines and tertiary amines such as trimethylamine, triethylamine, dimethylethylamine, dimethylmonoethanolamine and triethanolamine. The neutralizing agent used for the salt of the compound (a31) may be used alone or in combination of two or more.

As the neutralizing agent used for the salt of the compound (a31), a compound having a high vapor pressure at 25 ° C. is suitable from the viewpoint of the drying property of the ink composition and the water resistance of the obtained film. From this point of view, as the neutralizing agent used for the salt of the compound (a31), ammonia, monomethylamine, monoethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine and dimethylethylamine are preferable.

Among these, 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid and salts thereof are preferable, and ammonia or carbon of 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid is preferable. Neutralizing salts with amine compounds of numbers 1 to 20 are more preferred. By using such a compound (a31), the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved, and the flexibility and mechanical characteristics of the coating film tend to be further improved.

11.1.1.3.2. Compound (a32)
Examples of the compound (a32) containing a cationic group and an active hydrogen atom include a compound having a tertiary amino group as a cationic group and a hydroxyl group as an active hydrogen atom, and a tertiary amino group having 1 to 20 carbon atoms. Diols [N-alkyldialkanolamines (eg N-methyldiethanolamine, N-propyldiethanolamine, N-butyldiethanolamine and N-methyldipropanolamine) and N, N-dialkylmonoalkanolamines (eg N, N-dimethylethanolamine) ) Etc.] and the like, and examples thereof include salts obtained by neutralizing a compound such as with a neutralizing agent. Among these, a compound having two or more hydroxyl groups is preferable, and a tertiary amino group-containing diol is more preferable.

Examples of the neutralizing agent used for the salt of the compound (a32) include monocarboxylic acids having 1 to 10 carbon atoms (formic acid, acetic acid, propanoic acid, etc.), carbonic acid, dimethyl carbonate, dimethyl sulfate, methyl chloride, benzyl chloride and the like. Can be mentioned.

The neutralizing agent used for the salt of the compound (a31) and the compound (a32) is either before the urethanization reaction, during the urethanization reaction, after the urethanization reaction, before the water dispersion step, during the water dispersion step or after the water dispersion. Although it may be added at the same time, it is preferably added before the water dispersion step or during the water dispersion step from the viewpoint of the stability of the urethane resin (U) and the stability of the aqueous dispersion. Further, the neutralizing agent volatilized at the time of solvent removal may be added after the solvent is removed, and the neutralizing agent type to be added can be freely selected from the above.

The content of the ionic group introduced by the compound (a3) in the urethane resin (U) is preferably 0.1 to 1.5 mmol / g based on the weight of the urethane resin (U), more preferably. Is 0.1 to 1.2 mmol / g, more preferably 0.1 to 0.9 mmol / g.

The content of the ionic group in the present embodiment means the mass% of the unneutralized cationic group or the anionic group, and does not include the weight of the counterion. For example, the content of the ionic group in the compound (a31) is, in the case of the triethylamine salt of 2,2-dimethylolpropionic acid, the mass% of the carboxyl group (-COOH), 3- (2,3-dihydroxypropoxy). ) -1-In the case of the triethylamine salt of propanesulfonic acid, it refers to the mass% of the sulfo group (-SO ₃ H). Further, the content of the ionic group in the compound (a32) refers to the mass% of only the nitrogen atom in the tertiary amino group.

11.1.1.1.4. Chain extender (a4)
The chain extender (a4) is not particularly limited, and is, for example, water, an aliphatic polyamine having 2 to 36 carbon atoms [alkylenediamines such as ethylenediamine and hexamethylenediamine; diethylenetriamine, dipropylenetriamine, dihexylenetriamine, triethylene. Poly (n = 2 to 6) alkylene (2 to 6 carbon atoms) poly (n = 3 to 7) amines such as tetramine, tetraethylenepentamine, pentaethylenehexamine and hexaethyleneheptamine], 6 to 6 carbon atoms 20 alicyclic polyamines (1,3- or 1,4-diaminocyclohexane, 4,4'-or 2,4'-dicyclohexylmethanediamine and isophoronediamine, bicyclo [2.2.1] heptanedimethaneamine, etc. ), Aromatic polyamines with 6 to 20 carbon atoms (1,3- or 1,4-phenylenediamine, 2,4- or 2,6-tolylenediamine, 4,4'-or 2,4'-methylenebis Aniline, etc.), heterocyclic polyamines having 3 to 20 carbon atoms (2,4-diamino-1,3,5-triazine, piperazine, N-aminoethylpiperazine, etc.), hydrazines or derivatives thereof (dibasic acid dihydrazide, for example, adipine). Acid dihydrazide and the like) and amino alcohols having 2 to 20 carbon atoms (for example, ethanolamine, diethanolamine, 2-amino-2-methylpropanol and triethanolamine) and the like can be mentioned. The chain extender (a4) may be used alone or in combination of two or more.

11.1.1.1.4. Reaction terminator (a5)
The reaction terminator (a5) is not particularly limited, and is, for example, a monoalcohol having 1 to 20 carbon atoms (methanol, ethanol, butanol, octanol, decanol, dodecyl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, etc.), carbon. Examples thereof include monoamines having the number 1 to 20 (mono or dialkylamines such as monomethylamine, monoethylamine, monobutylamine, dibutylamine and monooctylamine, and mono- or dialkanolamines such as monoethanolamine, diethanolamine and diisopropanolamine). .. The reaction terminator (a5) may be used alone or in combination of two or more.

1.1.1.2. Organic polyisocyanate component (B)
The organic polyisocyanate component (B) is not particularly limited, but is, for example, an aromatic polyisocyanate (b1) having 2 to 3 or more isocyanate groups and having 8 to 26 carbon atoms, and a fat having 4 to 22 carbon atoms. Examples thereof include group polyisocyanates (b2), alicyclic polyisocyanates having 8 to 18 carbon atoms (b3), aromatic aliphatic polyisocyanates having 10 to 18 carbon atoms (b4), and modified products (b5) of these polyisocyanates. Will be. The organic polyisocyanate component (B) may be used alone or in combination of two or more.

The aromatic polyisocyanate (b1) is not particularly limited, and is, for example, 1,3- or 1,4-phenylenediocyanate, 2,4- or 2,6-tolylene diisocyanate (hereinafter, tolylene diisocyanate is TDI). , Crude TDI, 4,4'-or 2,4'-diphenylmethane diisocyanate (hereinafter, diphenylmethane diisocyanate is abbreviated as MDI), crude MDI, polyarylpolyisocyanate, 4,4'-diisocyanatobiphenyl, 3 , 3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4', 4 "-tri Examples thereof include phenylmethane triisocyanate and m- or p-isocyanatophenylsulfonyl isocyanate.

The aliphatic polyisocyanate (b2) is not particularly limited, and for example, ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter abbreviated as HDI), dodecamethylene diisocyanate, 1,6,11-undecantry isocyanate, and the like. 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate and 2-isocyanatoethyl -2,6-Diisocyanatohexanoate can be mentioned.

The alicyclic polyisocyanate (b3) is not particularly limited, and is, for example, isophorone diisocyanate (hereinafter abbreviated as IPDI), 4,4'-dicyclohexylmethane diisocyanate (hereinafter abbreviated as hydrogenated MDI), and cyclohexylene diisocyanate. , Methylcyclohexylene diisocyanate, bis (2-isosyanatoethyl) -4-cyclohexene-1,2-dicarboxylate and 2,5- or 2,6-norbornan diisocyanate.

The aromatic aliphatic polyisocyanate (b4) is not particularly limited, and examples thereof include m- or p-xylylene diisocyanate and α, α, α', α'-tetramethylxylylene diisocyanate.

The modified product (b5) includes modified products (urethane group, carbodiimide group, alohanate group, urea group, biuret group, uretdione group, uretoimine group, isocyanurate group or oxazolidone group) of the polyisocyanates (b1) to (b4). Modified products, etc .; those with a free isocyanate group content of 8 to 33% by mass, preferably 10 to 30% by mass, particularly 12 to 29% by mass), for example, modified MDIs (urethane-modified MDI, carbodiimide-modified MDI and trihydrocarbyl phosphate). Modified products of polyisocyanate such as modified MDI), urethane-modified TDI, biuret-modified HDI, isocyanurate-modified HDI and isocyanurate-modified IPDI.

Among the organic polyisocyanate components (B), the alicyclic polyisocyanate (b3) is preferable, and IPDI is more preferable. By using such an organic polyisocyanate component (B), the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved.

1.1.1.3. Other Physical Properties The urethane group concentration of the urethane resin (U) is preferably 1.0 to 2.7 mmol / g, more preferably 1.3 to 2.5 mmol / g, based on the weight of the urethane resin (U). It is more preferably 1.5 to 2.3 mmol / g. When the urethane group concentration is within the above range, the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved, and the flexibility and mechanical properties of the coating film tend to be further improved.

The urea group concentration of the urethane resin (U) is preferably 0.1 to 0.7 mmol / g, more preferably 0.2 to 0.6 mmol / g, based on the weight of the urethane resin (U). , More preferably 0.3 to 0.5 mmol / g. When the urea group concentration is within the above range, the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved, and the flexibility and mechanical characteristics of the coating film tend to be further improved.

The number average molecular weight of the urethane resin (U) is preferably 10,000 to 1,000,000. When the number average molecular weight is within the above range, the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved, and the flexibility and mechanical characteristics of the coating film tend to be further improved. The Mn of the urethane resin (U) can be measured by gel permeation chromatography, for example, under the following conditions.
-Device: "HLC-8220GPC" [manufactured by Tosoh Corporation] Column: "Guardcolumn α" + "TSKgel α-M" [both manufactured by Tosoh Corporation] Sample solution: 0.125% by mass of dimethylformamide solution Solution injection volume: 100 μl
・ Flow rate: 1 ml / min ・ Measurement temperature: 40 ° C
・ Detection device: Refractive index detector ・ Reference material: Standard polystyrene

The urethane resin (U) can be prepared as a dispersion and added to the clear ink composition. Additives such as antioxidants, color inhibitors, weather stabilizers, plasticizers and mold release agents can be added to the urethane resin (U), if necessary. The amount of these additives used is preferably 10% by mass or less, more preferably 3% by mass or less, and particularly preferably 1% by mass or less, based on the weight of the urethane resin (U).

1.1.1.4. Dispersant (H)
The urethane resin (U) can be dispersed in an aqueous medium using the dispersant (H) instead of the compound (a3) or in combination with the compound (a3), but the resulting dry film is water resistant. From the viewpoint of sex, it is preferable to use a self-emulsifying aqueous dispersion using only compound (a3).

Dispersants (H) include nonionic surfactants (h1), anionic surfactants (h2), cationic surfactants (h3), amphoteric surfactants (h4) and other emulsified surfactants (h4). h5) can be mentioned. In (H), one type may be used alone or two or more types may be used in combination.

Examples of the nonionic surfactant (h1) include an AO-added nonionic surfactant and a polyhydric alcohol type nonionic surfactant. The AO addition type includes an EO addition of an aliphatic alcohol having 10 to 20 carbon atoms, an EO addition of phenol, an EO addition of nonylphenol, an EO addition of an alkylamine having 8 to 22 carbon atoms, and an EO addition of polypropylene glycol. Examples of the polyhydric alcohol type include polyhydric (3 to 8 or more) alcohols (2 to 30 carbon atoms) and fatty acid (8 to 24 carbon atoms) esters (for example, glycerin monostearate and glycerin). Examples thereof include monooleate, sorbitan monolaurate and sorbitan monooleate) and alkyl (carbon number 4 to 24) poly (polymerization degree 1 to 10) glycoside.

Examples of the anionic surfactant (h2) include ether carboxylic acids having a hydrocarbon group having 8 to 24 carbon atoms or salts thereof [sodium lauryl ether acetate and (poly) oxyethylene (additional moles 1 to 100) lauryl ether. Sodium acetate, etc.]; Sulfate or ether sulfate having a hydrocarbon group having 8 to 24 carbon atoms and salts thereof [sodium lauryl sulfate, (poly) oxyethylene (additional moles 1 to 100) sodium lauryl sulfate, (poly). ) Oxyethylene (additional moles 1 to 100) triethanolamine lauryl sulfate and (poly) oxyethylene (additional moles 1 to 100) coconut oil fatty acid monoethanolamide sodium sulfate, etc.]; hydrocarbon groups having 8 to 24 carbon atoms Sodium dodecylbenzene sulphate, etc.; Sodium sulphonate having one or two hydrocarbon groups having 8 to 24 carbon atoms; Phosphoric acid ester or ether having a hydrocarbon group having 8 to 24 carbon atoms. Phosphoric acid esters and their salts [sodium lauryl phosphate and (poly) oxyethylene (additional moles 1 to 100) sodium lauryl ether phosphate, etc.]; fatty acid salts having a hydrocarbon group having 8 to 24 carbon atoms [lauric acid. Sodium and triethanolamine lauric acid, etc.]; and acylated amino acid salts having a hydrocarbon group having 8 to 24 carbon atoms [sodium coconut oil fatty acid methyl taurine, sodium coconut oil fatty acid sarcosine sodium, coconut oil fatty acid sarcosine triethanolamine, N- Palm oil fatty acid acyl-L-glutamate triethanolamine, N-coconut oil fatty acid acyl-L-sodium glutamate, sodium lauroylmethyl-β-alanine, etc.] can be mentioned.

Examples of the cationic surfactant (h3) include quaternary ammonium salt type [stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, disstearyldimethylammonium chloride, lanolin fatty acid ethylsulfate fatty acid aminopropylethyldimethylammonium, etc.] and amine salt type. [Diethylaminoethylamide stearate, dilaurylamine hydrochloride, oleylamine, etc.] can be mentioned.

Examples of the amphoteric surfactant (h4) include betaine-type amphoteric surfactants [coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium. Betaine, lauryl hydroxysulfobetaine and lauroylamide ethyl hydroxyethylcarboxymethyl betaine sodium hydroxypropyl phosphate, etc.] and amino acid-type amphoteric surfactants [β-lauryl aminopropionate, etc.] can be mentioned.

Other emulsifying dispersants (h5) include, for example, polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as carboxymethyl cellulose, methyl cellulose and hydroxyethyl cellulose, carboxyl group-containing (co) polymers such as sodium polyacrylic acid, and US Patent No. 1 Examples thereof include the emulsifying dispersant having a urethane group or an ester group described in the specification of No. 5906704 [for example, a polycaprolactone polyol in which a polyether diol is linked with a polyisocyanate].

The dispersant (H) may be added at any time after the urethanization reaction of the urethane resin (U), before the water dispersion step of (U), during the water dispersion step, or after the water dispersion, but (U). From the viewpoint of dispersibility and stability of the aqueous dispersion, it is preferable to add it before the water dispersion step or during the water dispersion step.

When the dispersant (H) is used, its content is based on the weight of the urethane resin (U) from the viewpoint of the water resistance of the dry film, the dispersibility of the urethane resin (U), and the stability of the aqueous dispersion. It is preferably 0.01 to 15% by mass, more preferably 0.01 to 10% by mass, and even more preferably 0.01 to 5% by mass.

1.1.1.5. Method for Producing Urethane Resin Examples of the method for producing the urethane resin (U) include the following methods [1] and [2].

[1] Active hydrogen containing a high molecular weight polyol component (a1) and, if necessary, a low molecular weight polyol component (a2), a compound (a3), a chain extender (a4), and a reaction terminator (a5). The component (A) and the organic polyisocyanate component (B) are reacted in one step or multiple steps in the presence or absence of the organic solvent (S) to produce a urethane resin (U), and if necessary, the compound (a3). ) Is used as a salt with a neutralizing agent and dispersed in an aqueous medium, and then the organic solvent (S) is distilled off if necessary.

[2] An active hydrogen component (A) containing a high molecular weight polyol component (a1) and, if necessary, a low molecular weight polyol component (a2), a compound (a3), and a chain extender (a4), and an organic poly. The isocyanate component (B) is reacted in one step or multiple steps in the presence or absence of the organic solvent (S) to produce a urethane prepolymer (P) having an isocyanate group, and then, if necessary, the prepolymer (P). The hydrophilic group moiety introduced by the compound (a3) in the compound (a3) is dispersed in an aqueous medium as a salt by neutralization, and a chain extender (a4) and / or a reaction terminator (a5) is added to the isocyanate in the prepolymer (P). A method of distilling off an organic solvent (S), if necessary, after reacting until no group is detected.

Of the methods [1] and [2], the method [2] is preferable from the viewpoint of the dispersion stability of the urethane resin (U) and the mechanical strength of the dry film.

Further, from the viewpoint of dispersion stability of the urethane resin (U), a method of producing the urethane prepolymer (P) in multiple stages to produce the aqueous dispersion (Q) of the urethane resin is more preferable, and particularly the polyester polyol (a12). The presence of the organic solvent (S) contains the polymer polyol component (a1) other than the above, the active hydrogen component (A) containing the components (a2) to (a4) if necessary, and the organic polyisocyanate component (B). After reacting under or in the absence to produce a urethane prepolymer (P1) having an isocyanate group, the obtained urethane prepolymer (P1) is reacted with a polyester polyol (a12) to produce a urethane prepolymer having an isocyanate group. The polymer (P2) is produced, and if necessary, the ionic group moiety introduced by the compound (a3) in the prepolymer (P2) is dispersed in an aqueous medium as a salt by neutralization to (a4) and / or (. A method of reacting a5) until the isocyanate group in the prepolymer (P2) is no longer detected and then distilling off the organic solvent (S), if necessary, is preferable.

The reaction temperature at the time of producing the urethane resin (U) in the method [1] and the urethane prepolymer (P) in the method [2] is preferably 60 to 120 ° C. from the viewpoint of suppressing side reactions. The temperature is preferably 60 to 110 ° C, more preferably 60 to 100 ° C. The production time can be appropriately selected depending on the equipment to be used, but is preferably 1 minute to 100 hours, more preferably 3 minutes to 30 hours, and further preferably 5 minutes to 20 hours.

The organic solvent (S) that can be used in the production of the aqueous dispersion (Q) is selected from solvents that are non-reactive with isocyanate groups, such as ketone solvents (eg acetone and methyl ethyl ketone), ester solvents [eg ethyl acetate, di. Basic acid ester (DBE)], ether solvent such as tetrahydrofuran), amide solvent (eg N, N-dimethylformamide and N-methylpyrrolidone), aromatic hydrocarbon solvent (eg toluene) and the like. These organic solvents (S) may be used alone or in combination of two or more. Further, the aqueous medium of the present embodiment means water or a mixture of water and an organic solvent (S).

The organic solvent (S) is preferably an organic solvent having a boiling point of less than 100 ° C., and examples thereof include acetone, methyl ethyl ketone, ethyl acetate and tetrahydrofuran. When an organic solvent having a boiling point of 100 ° C. or higher is used, it becomes difficult to completely remove only the organic solvent from the aqueous medium, and it remains in the aqueous dispersion, and the organic solvent is generated during drying, which is not preferable. Further, the organic solvent tends to remain in the film, and the mechanical properties of the film change with time, which is not preferable.

The content of the organic solvent (S) in the aqueous dispersion (Q) is preferably 1% by mass or less based on the weight of (Q) from the viewpoints of odor, stability over time, environmental load and safety. , More preferably 0.8% by mass or less, and more preferably 0.5% by mass or less.

In the urethanization reaction in the above methods [1] and [2], a known urethanization catalyst or the like can be used, if necessary, in order to accelerate the reaction. The amount of the urethanization catalyst added is preferably 0.001 to 3% by mass, more preferably 0.005 to 2% by mass, and further, based on the weight of the urethane resin (U) or the prepolymer (P). It is preferably 0.01 to 1% by mass.

The urethanization catalyst is not particularly limited, and is, for example, a metal catalyst [tin-based catalyst (trimethyltin laurate, trimethyltin hydroxyside, dimethyltin dilaurate, dibutyltin diacetate, dibutyltin dilaurate, stanas octoate and dibutyltin malee). Amine, etc.), lead-based catalysts (lead oleate, lead 2-ethylhexanoate, lead naphthenate, lead octenoate, etc.), cobalt-based catalysts (cobalt naphthenate, etc.), bismuth-based catalysts {bismastris (2-ethylhexa) Noate, etc.) and mercury-based catalysts (phenylmercury propionate, etc.)}, amine catalysts [triethylenediamine, tetramethylethylenediamine, tetramethylhexylenediamine, diazabicycloalkene {1,8-diazabicyclo [5.4. 0] -7-Undecene} etc .; Dialkylaminoalkylamine {dimethylaminoethylamine, dimethylaminopropylamine, diethylaminopropylamine, dibutylaminoethylamine, dimethylaminooctylamine, dipropylaminopropylamine, etc.} or heterocyclic aminoalkylamine Carbonate or organic acid salt (gerate, etc.) of [2- (1-aziridinyl) ethylamine and 4- (1-piperidinyl) -2-hexylamine, etc.]; N-methylmorpholin, N-ethylmorpholin, triethylamine, etc. Diethylethanolamine, dimethylethanolamine, etc.] and mixtures of two or more of these.

The apparatus for dispersing the urethane resin (U) or its organic solvent solution in the method [1] above, and the urethane prepolymer (P) or its organic solvent solution in the method [2] above is not particularly limited, but is rotational. It is preferable to use a type dispersion mixing device, an ultrasonic type dispersion machine or a kneading machine, and among them, a rotary type dispersion mixing device having a particularly excellent dispersion ability is more preferable.

As the rotary dispersion mixing device, for example, a mixing device having a general stirring blade such as a max blend or a helical blade, a TK homomixer [manufactured by Primix Co., Ltd.], a clear mix [manufactured by M-Technique Co., Ltd.], and a fill mix. [Primix Co., Ltd.], Ultra Turlux [IKA Co., Ltd.], Ebara Milder [Ebara Corporation], Cavitron (Eurotech Co., Ltd.) and Biomixer [Nippon Seiki Co., Ltd.], etc. Is represented as an example.

The volume average particle size (Dv) of the urethane resin (U) in the aqueous dispersion (Q) is preferably 0.01 to 1.0 μm, more preferably 0.01 to 0.5 μm. When the volume average particle diameter (Dv) is 0.01 μm or more, the viscosity of the aqueous dispersion (Q) is appropriate and the handleability tends to be further improved. Further, when the volume average particle diameter (Dv) is 0.5 μm or less, the dispersion stability of the aqueous dispersion (Q) tends to be further improved.

The volume average particle size (Dv) of the urethane resin (U) is controlled by the ionic group, the neutralizing agent, the amount of the dispersant, the type of the disperser used in the dispersion step, and the dispersion conditions in the urethane resin (U). Can be done. The volume average particle size (Dv) can be measured by a light scattering particle size distribution measuring device. For example, "LA950 V2" manufactured by HORIBA, Ltd. can be mentioned.

The viscosity of the aqueous dispersion (Q) at 25 ° C. is preferably 5000 mPa · s or less, more preferably 1000 mPa · s or less, from the viewpoint of handleability. The viscosity can be measured using a BL type viscometer.

The pH of the aqueous dispersion (Q) at 25 ° C. is preferably 2 to 12, more preferably 4 to 10, from the viewpoint of dispersion stability. The pH can be measured using pHMeter M-12 [manufactured by HORIBA, Ltd.].

11.2. Urethane resin (F)
The urethane resin (F) contains at least one of the structural unit represented by the general formula (1) and / or the structural unit represented by the general formula (2) and the structural unit represented by the general formula (3). It is a urethane resin that does not have and has a structural unit having a fluorene group. That is, the urethane resin (F) is a urethane resin other than the urethane resin (U) and has a fluorene group. As the method for producing the urethane resin (F), the above-mentioned method for producing the urethane resin (U) can be used.

By further using the urethane resin (F) in addition to the urethane resin (U), the abrasion resistance to a wide range of recording media from polar recording media to low polar recording media is further improved, and the laminating peel resistance and continuous printing stability are further improved. There is a tendency for the sex and clogging recovery to be further improved.

The urethane resin (F) is preferably added to the ink composition as an aqueous dispersion, and the urethane resin (F) is preferably dispersed as resin fine particles in the clear ink composition.

The content of the urethane resin (F) is preferably 0.1 to 5.0% by mass, more preferably 0.3 to 3.0% by mass, and further, with respect to the total amount of the clear ink composition. It is preferably 0.5 to 2.0% by mass. When the content of the urethane resin (U) is within the above range, the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved.

The urethane resin (F) can be obtained as a polymer of a polyisocyanate having a fluorene group and a polyol, a polymer of a polyol having a polyisocyanate and a fluorene group, or a polymer of a polyisocyanate having a fluorene group and a polyol having a fluorene group. Can be done. Further, in the synthesis of the urethane resin (F), the above-mentioned chain extender (a4), reaction terminator (a5) and the like can also be used, if necessary.

The polyol having a fluorene group is not particularly limited, but for example, 9,9-bis (4- (hydroxyalkoxy) phenyl) fluorene having a hydroxyalkoxy having 1 to 4 carbon atoms, 9,9-bis (4-hydroxy). Examples thereof include phenyl) fluorene, 9,9-bis (4-hydroxytoluyl) fluorene, and 9,9-bis (hydroxyalkyl) fluorene having a hydroxyalkyl group having 1 to 4 carbon atoms.

The urethane resin (F) may contain other polyols having no fluorene group, if necessary, in addition to the above-mentioned polyols. Examples of other polyols include polyols other than the polyolefin polyol (a11) and the polyester polyol (a12) among the polyols described in the urethane resin (U).

As such other polyols, a polyester polyol (a131), a polyether polyol (a132), and a compound (a3) having two or more hydroxyl groups are preferable, and a polyether polyol (a132) and a dialkylol alkanoic acid are more preferable. .. By using such a polyol, the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved.

Examples of the polyisocyanate used for synthesizing the urethane resin (F) include those similar to those exemplified for the organic polyisocyanate (B). Of these, alicyclic polyisocyanate (b3) is preferable, and 4,4'-dicyclohexylmethane diisocyanate is more preferable. By using such a polyisocyanate, the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved.

11.3. Urethane resin (A)
The urethane resin (A) is a structural unit represented by the general formula (1) and / or a structural unit represented by the general formula (2) and at least one of the structural units represented by the general formula (3). , With no constituent unit having a fluorene group, and derived from any of m-bis (isocyanatepropyl) benzene, m-bis (isocyanatemethyl) benzene, tolylene diisocyanate, or 4,4-diphenylmethane diisocyanate. It is a urethane resin having a structure to be used. That is, the urethane resin (A) is a urethane resin other than the urethane resin (U) and the urethane resin (F), and is m-bis (isocyanate propyl) benzene, m-bis (isocyanate methyl) benzene, tolylene diisocyanate, and the like. Alternatively, it has a structure derived from any of 4,4-diphenylmethane diisocyanate. As the method for producing the urethane resin (A), the above-mentioned method for producing the urethane resin (U) can be used.

By further using the urethane resin (A) in addition to the urethane resin (U), the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media is further improved. Further, each of the urethane resins (A) has an aromatic ring and tends to easily crystallize or stack when polymerized to form a polymer. Therefore, the mechanical strength of the obtained coating film tends to be further improved.

The urethane resin (A) is preferably added to the ink composition as an aqueous dispersion, and the urethane resin (A) is preferably dispersed as resin fine particles in the clear ink composition.

The content of the urethane resin (A) is preferably 1.0 to 7.0% by mass, more preferably 1.5 to 6.0% by mass, and further, with respect to the total amount of the clear ink composition. It is preferably 2.0 to 5.0% by mass. When the content of the urethane resin (A) is within the above range, the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved.

The urethane resin (A) can be obtained as a polymer of the above-mentioned predetermined polyisocyanate and polyol. Further, in the synthesis of the urethane resin (A), the above-mentioned chain extender (a4), reaction terminator (a5) and the like can also be used, if necessary.

11.3.1. Polyisocyanate The polyisocyanate used for the polymerization of the urethane resin (A) is required in addition to m-bis (isocyanatepropyl) benzene, m-bis (isocyanatemethyl) benzene, tolylene diisocyanate, or 4,4-diphenylmethane diisocyanate. Depending on the above, the aliphatic polyisocyanate (b2), the alicyclic polyisocyanate (b3), the aromatic aliphatic polyisocyanate (b4) and the modified polyisocyanate (b5) exemplified in the organic polyisocyanate (B) are used. May be. By using such a polyisocyanate, the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved.

11.3.2. Polyol The polyol used for the polymerization of the urethane resin (A) is not particularly limited, but is, for example, a condensed polyester polyol, a polylactone polyol, or a polycarbonate diol other than the polyester polyol (a12) exemplified as the polyester polyol (a131). And castor oil-based polyols; polyether polyols (a132); low molecular weight polyol components (a2); compounds having two or more hydroxyl groups (a3) and the like. Moreover, the above can also be used. These polyols do not have a structural unit represented by the general formula (1) and / or a structural unit represented by the general formula (2) and a structural unit represented by the general formula (3).

Among these, the polyester polyol (a131), the polyether polyol (a132), and the compound (a3) having two or more hydroxyl groups are preferable, and the polyester polyol (a131) and dialkylol alkanoic acid are more preferable. By using such a polyol, the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved.

The number average molecular weight of the polyol used for the polymerization of the urethane resin (A) is preferably 250 to 4000, more preferably 500 to 3000, and even more preferably 1000 to 2500. When the number average molecular weight is within the above range, the abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media tends to be further improved.

1.2. Water The clear ink composition of the present embodiment is a water-based ink containing water as a solvent. As a result, the resin can be easily dispersed in the form of an emulsion, and an image having further excellent fixability and scratch resistance can be easily formed by an inkjet method.

The water content is preferably 45% by mass or more with respect to the total amount of the clear ink composition. Further, it is preferably 98% by mass or less. It is more preferably 55 to 85% by mass, more preferably 60 to 80% by mass, and further preferably 65 to 75% by mass. When the water content is within the above range, the clear ink composition can have a relatively low viscosity. The water in the clear ink composition includes, for example, water coming from a polymer particle dispersion liquid, a pigment dispersion liquid, water to be added, or the like used as a raw material.

1.3. Silicone The clear ink composition of the present embodiment may further contain silicone. Examples of the silicone include oil-type silicones and silicone emulsions (emulsion-type silicones), and silicone emulsions are preferable. Hereinafter, dimethyl silicone will be described as an example of silicone. One type of silicone may be used alone, or two or more types may be used in combination. By containing such silicone, the abrasion resistance of the coating film tends to be improved for a wide range of recording media from polar recording media to low-polarity recording media.

Examples of the dimethyl silicone include an oil-type dimethyl silicone (e1) and an emulsion-type dimethyl silicone (e2) in which an oil-type dimethyl silicone (e1) is dispersed in an aqueous medium with a dispersant.

Commercially available oil-type dimethyl silicone oil (e1) includes SH200 series [manufactured by Toray Dow Corning Co., Ltd.], KF-96 series [manufactured by Shin-Etsu Chemical Co., Ltd.] and TSF451 series [Momentive Performance Materials. Made by Japan GK], etc.

Commercially available products of emulsion type dimethyl silicone (e2) include SM8706EX, FSXE-2098, IE-7045, SM7036EX, IE7046T and SM8701EX [manufactured by Toray Dow Corning Co., Ltd.], POLONMF-7, POLON MF-17, POLON MF. -32 and POLON MF-33 [manufactured by Shin-Etsu Chemical Co., Ltd.] and TSM630, TSM631, TSM6344 and TSM6343 [manufactured by Momentive Performance Materials Japan GK] and the like.

Among these, emulsion type dimethyl silicone (e2) is preferable from the viewpoint of dispersion stability of the aqueous dispersion (Q).

The content of the silicone is preferably 0.2 to 15% by mass, more preferably 0.5 to 10% by mass, still more preferably 1.0 to 5% by mass, based on the weight of the urethane resin (U). It is mass%. When the content of silicone is within the above range, the adhesion and abrasion resistance of the obtained coating film tend to be further improved.

The content of silicone is preferably 0.2 to 5.0% by mass, more preferably 0.3 to 3.0% by mass, and even more preferably 0.% by mass, based on the total amount of the clear ink composition. It is 5 to 1.5% by mass. When the content of silicone is within the stated range, the obtained dispersion stability and the abrasion resistance and water resistance of the coating film tend to be further improved.

When silicone is used in an emulsion state, the above-mentioned content means the solid content thereof. Further, the above-mentioned content is the total amount of silicone in the ink, and when silicone is contained in the dispersion of the urethane resin (U), the above-mentioned content shall also include the content.

1.4. Polyolefin Wax The clear ink composition of the present embodiment may further contain a polyolefin wax. The polyolefin wax is not particularly limited, and examples thereof include those obtained by copolymerizing an olefin and a diene, and a polyolefin wax emulsion is preferable. By including such a polyolefin wax, the abrasion resistance of the coating film tends to be improved for a wide range of recording media from polar recording media to low-polarity recording media.

Examples of the olefin include ethylene and α-olefin having 3 to 12 carbon atoms. Examples of the α-olefin having 3 to 12 carbon atoms include propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, and 3-methyl-1. -Pentene, 1-octene, 1-decene, 1-dodecene and the like can be mentioned. Of these, α-olefins having 3 to 10 carbon atoms are preferable, α-olefins having 3 to 8 carbon atoms are more preferable, and propylene, 1-butene, 1-hexene, and 4- are particularly preferable. Methyl-1-pentene.

Examples of the diene include butadiene, isoprene, 4-methyl-1,3-pentadiene, 1,3-pentadiene, 1,4-pentadiene, 1,5-hexadiene, 1,4-hexadiene, and 1,3-hexadiene. 1,3-octadien, 1,4-octadien, 1,5-octadien, 1,6-octadien, 1,7-octadien, ethylidene norbornene, vinylnorbornene (5-vinylbicyclo [2.2.1] hepto-2 -En), dicyclopentadiene, 2-methyl-1,4-hexadiene, 2-methyl-1,6-octadien, 7-methyl-1,6-octadien, 4-ethylidene-8-methyl-1,7- Norbornene, 5,9-dimethyl-1,4,8-decatorien and the like can be mentioned. Of these, vinyl norbornene, ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, butadiene, isoprene, 2-methyl-1,4-hexadiene or 2-methyl-1,6-octadien are preferred.

Further, the polyolefin wax may be an oxidized polyolefin wax obtained by oxidizing the polyolefin wax by a known method. The oxidized polyolefin wax can be produced, for example, by introducing an oxygen atom or the like into the molecule while adjusting the high molecular weight polyolefin resin to a desired molecular weight by thermal decomposition, chemical decomposition, or the like. The oxygen atom introduced into the molecule constitutes, for example, a polar carboxyl group or the like. In the present invention, it is preferable to use an oxidized polyolefin wax because it can be easily emulsified in an aqueous solvent.

Further, from the viewpoint of improving wear resistance and excellent gloss of printed matter, it is preferable to contain at least one selected from paraffin wax and sazole wax. The paraffin wax is a wax composed of a mixture of chain saturated hydrocarbons having 20 or more carbon atoms. Sazole wax (Fischer-Tropsch wax) is produced by a method of synthesizing hydrocarbons by hydrogenation reaction of carbon monoxide using coal as a raw material, and consists of saturated linearly linked hydrocarbons. It is a synthetic wax characterized by having an almost perfect linear molecular structure with almost no branches.

The melting point of the polyolefin wax is preferably 85 to 120 ° C, more preferably 90 to 120 ° C, and even more preferably 95 to 120 ° C. When the melting point is 85 ° C. or higher, the abrasion resistance tends to be further improved. Further, when the melting point is 120 ° C. or lower, it becomes easy to adjust the average particle size of the wax emulsion to 140 nm or less, the amount of the surfactant used when preparing the emulsion can be suppressed, and the wax emulsion can be suppressed. The dispersion stability of the ink composition is improved, and the water resistance and solvent resistance of the ink composition are improved.

Further, the polyolefin wax is preferably a polyolefin wax emulsion. The average particle size of the polyolefin wax emulsion is preferably 30 to 200 nm, more preferably 30 to 140 nm, and even more preferably 30 to 120 nm. When the average particle size is 200 nm or less, the dispersion stability, the ejection property and the glossiness of the printed matter tend to be further improved. Further, when the average particle size is 30 nm or more, the abrasion resistance, particularly the dry friction resistance tends to be further improved.

The method for forming the polyolefin wax into an emulsion state is not particularly limited, and a conventionally known method may be appropriately selected. For example, a method of mixing a known surfactant with a polyolefin wax, other waxes used as necessary, and the like can be mentioned. As the surfactant used in the polyolefin wax emulsion, a surfactant having a relatively high lipophilicity is preferable, and specifically, an alkoxylate of a long-chain alcohol and a salt thereof, a polyoxyalkylene alkyl ether and a salt thereof, and a polyoxy. Alkylene fatty acid alcohols, glycerin fatty acid esters, sorbitan fatty acid esters and the like are preferable.

As a commercial product of polyolefin wax, the product name "AC8" manufactured by Honeywell Co., Ltd.
(Polyethylene wax), trade name "VISCOWAX" manufactured by INNOSPEC
122 "(polyethylene wax), product name" A-C400 "(ethylene-vinyl acetate copolymer system wax) manufactured by Honeywell, product name" VISCOWAX 334 "(ethylene-vinyl acetate copolymer system wax) manufactured by INNOSPEC, "VISCOWAX 343" (ethylene-vinyl acetate copolymer wax) manufactured by INNOSPEC and polyethylene-based wax emulsions manufactured by Toho Kagaku Kogyo Co., Ltd., such as E-4B, E103N, E-1000, E-5403B, E-6000. , E-6314, E-6400, S-3121, S-3123, S-3125, S-3148, as a polypropylene-based wax emulsion, Hi-Tech E-433N, Hi-Tech E-5060, Roam and Hearth Japan Co., Ltd. ) As polyethylene wax emulsions, Polyem 20, Polyem 40J, and Mitsui Chemicals Co., Ltd. polyethylene wax Chemipearl W-100, W-200, W-300, W-308, W-310, W-400, W-401. , W-4005, W-410, W-500, WF-640, W-700, W-800, W-900, W-950 and W-4005, etc., are described in JP-A-2003-201436. Polyethylene resin, AQUACER1550, 497, 500 series, 840, 1000 series, 2500, 2650, 3500, 8075 and 8976, S-323, S-363, S-368N5T manufactured by Sherlock Technology Co., Ltd. , S-379, S-381, S-390C, S-394, S-395, S-395SD4, S-400, S-483, NEPUUNE-1, NEPUUNE-5031, NEPUUNE-968, NEPUUNE-5223N4, NEPUUNE -5331 and NEPUUNE-5918, carnauba wax emulsion WE-100 manufactured by Shinei Sangyo Co., Ltd., carnauba wax emulsion WE-1-252, wax emulsion manufactured by Nikko Fine Products Co., Ltd., and the like.

The content of the polyolefin wax is preferably 0.2 to 15% by mass, more preferably 0.5 to 10% by mass, and further preferably 1.0 to 1.0% by mass based on the weight of the urethane resin (U). It is 5% by mass. When the content of the polyolefin wax is within the above range, the adhesion and abrasion resistance of the obtained coating film tend to be further improved.

The content of the polyolefin wax is preferably 0.2 to 5.0% by mass, more preferably 0.3 to 3.0% by mass, and further preferably 0, based on the total amount of the clear ink composition. It is 5.5 to 1.5% by mass. When the content of the polyolefin wax is within the stated range, the obtained dispersion stability and the abrasion resistance and water resistance of the coating film tend to be further improved.

When the polyolefin wax is used in an emulsion state, the above-mentioned content means the solid content thereof. Further, the content of the silicone is the content of the solid content of the silicone in the ink. When these are contained in the dispersion of the urethane resin (U), the above-mentioned content shall include the content.

The ink preferably contains either polyolefin wax or silicone because it has better scratch resistance and the like. Silicone is more preferably a silicone emulsion.

1.5. Water-soluble organic solvent The clear ink composition of the present embodiment may contain a water-soluble organic solvent. By containing the water-soluble organic solvent, it is possible to effectively suppress the evaporation of water from the recording head when the ink composition is left for a long period of time, while improving the ejection stability of the ink composition by the inkjet method. In addition, the permeability of the ink is improved, and an image having excellent image quality, abrasion resistance, adhesion, and the like can be obtained.

The water-soluble organic solvent is not particularly limited, and examples thereof include polyols, glycol ethers, nitrogen-containing solvents, acyclic ertels, and cyclic esters. Of these, polyhydric alcohols, glycol ethers, and nitrogen-containing solvents are preferable. The water-soluble organic solvent may be used alone or in combination of two or more.

The above-mentioned polyols have an excellent action as a penetrating solvent for a recording medium, and the wettability of the ink composition with respect to the recording medium is further improved. Preferred examples of the polyols include an alkane polyol having two or more hydroxyl groups and a condensate of the alkane polyols intermolecularly condensed with each other. The number of condensations of the condensate is preferably 2-4. The number of hydroxyl groups of the polyols is preferably 2 to 5, more preferably 2 to 3.

Such polyols are not particularly limited, but are, for example, ethylene glycol, propylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-propanediol, 1,4-butanediol, and diethylene glycol. , Triethylene glycol, Dipropylene glycol, Trimethylolpropane, Glycerin, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,6-hexanediol, 2-methyl-2,4 -Pentanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl -1,3-propanediol, 3-methyl-1,3-butanediol, 2-ethyl-1,3-hexanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4- Examples include diol.

The content of the polyols is preferably 1 to 40% by mass, more preferably 2 to 30% by mass, and further preferably 5 to 25% by mass with respect to the total amount of the clear ink composition.

The glycol ethers are excellent in resin solubility and permeability, and the scratch resistance and adhesion of the obtained coating film tend to be further improved. Glycol ethers are monoethers or diethers of alkylene glycols or polyalkylene glycols. The alkylene glycol is preferably an alkylene glycol having 4 or less carbon atoms, and the polyalkylene glycol is preferably a condensate of these hydroxyl groups intermolecularly condensed. In the case of a condensate, the number of condensations is preferably 2-4. Examples of the ether include alkyl ethers and aromatic ethers, and among them, alkyl ethers are preferable. The alkyl of the alkyl ether preferably has 1 to 4 carbon atoms. Further, monoether is preferable.

Such glycol ethers are not particularly limited, but for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol mono. Ethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol monobutyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether , Propropylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, 3-methoxy-3-methyl-1-butanol, ethylene Examples thereof include glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether.

The number of carbon atoms of the glycol ethers is preferably 15 or less, more preferably 3 to 12, still more preferably 4 to 8, and even more preferably 4 to 7.

The content of the glycol ethers is preferably 1 to 40% by mass, more preferably 2 to 30% by mass, and further preferably 5 to 10% by mass with respect to the total amount of the clear ink composition.

The nitrogen-containing solvent may be any solvent containing a nitrogen atom in the molecule. The nitrogen-containing solvent acts as a good dissolving agent for the resin, and tends to further improve the abrasion resistance and adhesion of the obtained coating film. Examples of the nitrogen-containing solvent include dimethyl sulfoxide, cyclic amides, acyclic amides and the like.

The cyclic amides are not particularly limited as long as they are amides having a cyclic structure, and are, for example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone, and the like. Examples thereof include pyrrolidones such as N-butyl-2-pyrrolidone and 5-methyl-2-pyrrolidone.

The acyclic amides are not particularly limited as long as they are amides having an acyclic structure, and are, for example, 3-methoxy-N, N-dimethylpropionamide, 3-methoxy-N, N-diethylpropionamide, 3-. Methoxy-N, N-methylethylpropionamide, 3-ethoxy-N, N-dimethylpropionamide, 3-ethoxy-N, N-diethylpropionamide, 3-ethoxy-N, N-methylethylpropionamide, 3- n-butoxy-N, N-dimethylpropionamide, 3-n-butoxy-N, N-diethylpropionamide, 3-n-butoxy-N, N-methylethylpropionamide, 3-n-propoxy-N, N -Dimethylpropionamide, 3-n-propoxy-N, N-diethylpropionamide, 3-n-propoxy-N, N-methylethylpropionamide, 3-iso-propoxy-N, N-dimethylpropionamide, 3- iso-propoxy-N, N-diethylpropionamide, 3-iso-propoxy-N, N-methylethylpropionamide, 3-tert-butoxy-N, N-dimethylpropionamide, 3-tert-butoxy-N, N -Diethylpropionamide, 3-tert-butoxy-N, N-methylethylpropionamide and the like can be mentioned.

The content of the nitrogen-containing solvent is preferably 1 to 40% by mass, more preferably 2 to 30% by mass, still more preferably 3 to 20% by mass, based on the total amount of the clear ink composition. Particularly preferably, it is 5 to 10% by mass.

The acyclic esters are not particularly limited, and for example, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, and the like. Glycol monoacetates such as propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and methoxybutyl acetate; ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, Ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, dipropylene glycol acetate propionate, etc. Glycol diesters can be mentioned.

Examples of the cyclic esters include β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, and γ-hexano. Lactone, δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, Cyclic esters (lactones) such as δ-nonalactone, ε-nonalactone, and ε-decanolactone, as well as compounds in which the hydrogen of the methylene group adjacent to their carbonyl group is replaced by an alkyl group having 1 to 4 carbon atoms. be able to.

The content of the water-soluble organic solvent is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the total amount of the clear ink composition. On the other hand, the content of the water-soluble organic solvent is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, based on the total amount of the clear ink composition. When the content of the water-soluble organic solvent is in the above range, the abrasion resistance, the adhesiveness, the moisturizing property, the permeability and the like tend to be further improved.

The standard boiling point of the water-soluble organic solvent is preferably 160 ° C. or higher, more preferably 200 ° C. or higher, and even more preferably 210 ° C. or higher. On the other hand, the standard boiling point of the water-soluble organic solvent is preferably 300 ° C. or lower, preferably 280 ° C. or lower, more preferably 270 ° C. or lower, and even more preferably 260 ° C. Further, the temperature may be 210 ° C. or lower, or 190 ° C. or lower. When the standard boiling point of the water-soluble organic solvent is above the above range, the ejection stability of the ink composition is more excellent, while when the standard boiling point of the water-soluble organic solvent is below the above range, the adhesion and scratch resistance are improved. Better and preferred. In particular, the standard boiling point of polyhydric alcohols is preferably in the above range.

In addition, polyols having a standard boiling point of more than 280 ° C. such as glycerin may reduce the drying property of the ink when they adhere to the recording medium. Therefore, the content of the polyols having a standard boiling point of more than 280 ° C. is preferably 3% by mass or less, more preferably 2% by mass or less, and 1% by mass with respect to the total amount of the clear ink composition. % Or less, more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less. In this case, since the drying property of the ink composition on the recording medium is more excellent, the scratch resistance and adhesion are more excellent and preferable.

Further, it is further preferable that the content of the organic solvent having a standard boiling point of more than 280 ° C. in the clear ink composition is in the above range in the above-mentioned points. Here, the organic solvent having a standard boiling point of more than 280 ° C. is not limited to the above-mentioned polyols.

1.6. Surfactant The clear ink composition of the present embodiment may contain a surfactant. By containing a surfactant, the wettability and discharge stability tend to be further improved. Examples of the surfactant include a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant. In particular, silicone-based surfactants, acetylene glycol-based surfactants, and fluorine-based surfactants are preferable.

Such a surfactant is not particularly limited, and is, for example, an acetylene glycol-based surfactant; an acetylene alcohol-based surfactant; a polyoxyethylene nonylphenyl ether, a polyoxyethylene octylphenyl ether, and a polyoxyethylene dodecylphenyl ether. , Polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether and other ether-based surfactants; polyoxyethylene oleic acid, polyoxyethylene oleic acid Ethereal surfactants such as esters, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquiorate, polyoxyethylene monooleate and polyoxyethylene stearate; dimethylpolysiloxane Silicon-based surfactants such as; fluorine-based surfactants such as fluorine alkyl esters and perfluoroalkyl carboxylates. One type of surfactant may be used alone, or two or more types may be used in combination.

The content of the surfactant is preferably 0.01 to 3% by mass, more preferably 0.05 to 2% by mass, and further preferably 0.1 to 0.1% by mass with respect to the total amount of the clear ink composition. It is 1% by mass, and particularly preferably 0.2 to 0.5% by mass.

1.8. Other Ink The ink composition according to the present embodiment further comprises a pH adjuster, a chelating agent, a rust inhibitor, a fungicide, an antioxidant, a reduction inhibitor, an evaporation accelerator, a water-soluble resin, etc., as required. , Various additives may be contained.

2. 2. Ink set The ink set of the present embodiment includes the above clear ink composition and a water-based colored ink composition containing a coloring material. The colored ink composition can have each component exemplified in the above clear ink composition except that it contains a coloring material.

2.1. Colored ink composition 2.1.1. Coloring Material The coloring ink composition may contain a pigment, a dye, or the like as a coloring material. Of these, pigments are preferred. The coloring material may be used alone or in combination of two or more. The colored ink composition is an ink used for coloring a recording medium.

The pigment is not particularly limited, but is, for example, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, and inorganic pigments such as iron oxide and titanium oxide; quinacridone pigments. , Kinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthron pigments, flavanthron pigments, perylene pigments. , Kinophthalone-based pigments, anthraquinone-based pigments, thioindigo-based pigments, benzimidazolone-based pigments, isoindolinone-based pigments, azomethine-based pigments, and organic pigments such as azo-based pigments.

The pigment can be used as a dispersion. The method for dispersing the pigment is not particularly limited, but for example, a method for dispersing using a water-soluble resin, a method for dispersing using a surfactant, and a method for chemically and physically introducing a hydrophilic functional group on the surface of pigment particles. However, there are methods such as dispersion.

The content of the pigment is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, and further preferably 1.0 to 7.% of the total amount of the colored ink composition. It is 5% by mass. The content of the pigment can be appropriately changed by using it depending on the type of coloring material and the like.

In particular, when the pigment is a white pigment, the content of the pigment is preferably 5 to 30% by mass, more preferably 7.5 to 20% by mass, based on the total amount of the colored ink composition. Since the white ink is used for applications such as a base, the content of the white ink is relatively large in the colored ink composition. Since such a white ink contains a large amount of pigment, the scratch resistance tends to be relatively inferior. Therefore, the present invention is particularly useful.

2.2.1. The resin-colored ink composition may contain at least one of an acrylic resin, a urethane resin, and a polyester resin as the resin. Of these, urethane resin is preferable.

The urethane resin is not particularly limited, and examples thereof include urethane having a polyether structure, urethane having a polyester structure, urethane having a polycarbonate structure, and urethane having two or more of these structures. As such a urethane resin, in addition to the above urethane resins (U), (A), and (F), urethane resins other than these may be used.

Among them, a urethane resin other than the urethane resin (U), an acrylic resin, and a polyester resin are preferable, and an acrylic resin is more preferable, in that clogging recovery is more excellent.

The acrylic resin (acrylic resin) is a monomer containing at least acrylate or acrylic acid or a polymerized resin, and an acrylic resin polymerized from at least one of acrylate or acrylic acid and another monomer is preferable. A styrene acrylic resin using styrene as a monomer is more preferable. Such acrylic resins are not particularly limited, and are, for example, acrylic resins such as Movinyl 952B, 718A (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Nipol LX872, LX874 (trade name, manufactured by Nippon Zeon Corporation). Examples thereof include styrene acrylic resins such as John Krill 7100, 390 (trade name, manufactured by BASF), Movinyl 966A, 975N (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

The polyester resin (polyester resin) is not particularly limited, and examples thereof include polyethylene terephthalate.

The content of the resin contained in the colored ink composition is preferably 1.0 to 8.0% by mass, more preferably 2.0 to 7.0% by mass, based on the total amount of the colored ink composition. Yes, more preferably 3.0 to 6.0% by mass.

3. 3. Recording Method The recording method according to the present embodiment includes a clear ink adhering step of adhering the clear ink composition to a recording medium. Further, if necessary, it may have a colored ink adhering step of adhering the colored ink composition to a recording medium by an inkjet method.

As described above, by recording using the clear ink composition containing the urethane resin (U) instead of containing the urethane resin (U) in the colored ink composition containing the coloring material, the coloring material and the urethane are recorded. It is possible to avoid including the resin (U) in the same ink. Therefore, it is possible to avoid deterioration of ejection stability due to the coexistence of the coloring material and the urethane resin (U), and impart high abrasion resistance to a wide range of recording media from polar recording media to low-polarity recording media. be able to.

3.1. Recording medium The recording medium used in the recording method of the present embodiment is not particularly limited, and an absorbent recording medium, a low absorbency recording medium, or a non-absorbent recording medium can be used. Among them, a low-absorbency recording medium or a non-absorbent recording medium is preferable, and a non-absorbent recording medium is more preferable. The low-absorbency recording medium or non-absorbent recording medium refers to a recording medium having a property of not absorbing ink at all or hardly absorbing ink. Quantitatively, the recording medium used in the present embodiment refers to "a recording medium having a water absorption amount of 10 mL / m ² or less from the start of contact to 30 msec ^1/2 in the Bristow method". For details of the test method, refer to the standard No. of "JAPAN TAPPI Paper and Pulp Test Method 2000 Edition". 51 "Paper and Paperboard-Liquid Absorption Test Method-Bristow Method". Examples of the recording medium having such a non-absorbent property include a recording medium having an ink receiving layer having ink absorbency on the recording surface and a recording medium having a coat layer having low ink absorbency on the recording surface. ..

Examples of the absorbent recording medium include ink-absorbent paper and cloth. Examples of the ink-absorbent paper include plain paper and paper provided with an ink-absorbing layer. The absorbent recording medium is a recording medium having a water absorption amount of more than 10 mL / m ² from the start of contact to 30 msec ^1/2 in the above-mentioned Bristow method.

Examples of the low-absorbency recording medium include a recording medium having a coated layer having a low ink absorbency, which is called coated paper, on the recording surface.

The non-absorbent recording medium is not particularly limited, but for example, a plastic film having no ink absorbing layer, a paper coated with plastic on a base material such as paper, a plastic film adhered, or the like. Can be mentioned. Examples of the plastic referred to here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, acrylic resin and the like.

Further, the non-absorbent recording medium can be roughly classified into a polar recording medium and a low-polarity recording medium. In the polar recording medium, the material constituting the surface of the recording medium has a relatively large amount of polarity, and examples thereof include PET, nylon, ABS, and polycarbonate. In the low-polarity recording medium, the material constituting the surface of the recording medium has relatively low or no polarity, and examples thereof include polyolefins such as OPP and PE.

Due to the difference in polarity between the polar recording medium and the low-polarity recording medium, the adhesion and abrasion resistance of the coating film formed by adhering the ink may differ depending on the ink components. That is, depending on the ink components, there may be inks in which the characteristics of the recorded material are more easily obtained in the polar recording medium and inks in which the characteristics of the low-polarity recording medium are more easily obtained. In this case, it becomes difficult to obtain excellent characteristics for both the polar recording medium and the low-polarity recording medium at the same time. However, according to the ink of the present embodiment, excellent adhesion and scratch resistance can be obtained for both the polar recording medium and the low-polarity recording medium.

The ink composition of the present embodiment is more preferably used for recording on both a polar recording medium and a low-polarity recording medium. This makes it possible to record on both the polar recording medium and the low-polarity recording medium using the same device without changing the ink.

3.2. Colored Ink Adhesion Step The colored ink adhesion step is a step of adhering the colored ink composition to a recording medium. More specifically, the pressure generating means is driven to eject the colored ink composition filled in the pressure generating chamber of the inkjet head from the nozzle. Such a ejection method is also referred to as an inkjet method.

3.3. Clear ink adhesion step The clear ink adhesion step is a step of adhering the clear ink composition to the recording medium. More specifically, the pressure generating means is driven to eject the colored ink composition filled in the pressure generating chamber of the inkjet head from the nozzle. Such a ejection method is also referred to as an inkjet method. The clear ink composition of the present embodiment is useful as an ink composition ejected by an inkjet method because it has excellent ejection stability and excellent clogging recovery even if it contains a urethane resin (U).

Examples of the inkjet head used in the coloring ink adhering step and the clear ink adhering step include a line head that records by a line method and a serial head that records by a serial method.

In the line method using a line head, for example, an inkjet head having a width equal to or larger than the recording width of the recording medium is fixed to the inkjet device. Then, the recording medium is moved along the sub-scanning direction (vertical direction of the recording medium, transport direction), and in conjunction with this movement, ink droplets are ejected from the nozzle of the inkjet head to record an image on the recording medium. do.

In the serial system using a serial head, for example, the inkjet head is mounted on a carriage that can move in the width direction of the recording medium. Then, the carriage is moved along the main scanning direction (horizontal direction and width direction of the recording medium), and in conjunction with this movement, ink droplets are ejected from the nozzle opening of the head to record an image on the recording medium. be able to.

The order of the colored ink adhering step and the clear ink adhering step is not particularly limited, but for example, a method of adhering the colored ink composition to a recording medium and then adhering the clear ink composition to a region to which the colored ink composition is adhered. A method of adhering the clear ink composition to the recording medium and then adhering the colored ink composition to the region to which the clear ink composition is adhered can be mentioned. Among these, a method of adhering the colored ink composition to the recording medium and then adhering the clear ink composition to the region to which the colored ink composition is attached is preferable. As a result, the clear ink composition can be adhered so as to cover the colored ink composition adhering to the recording medium, and the adhesion and scratch resistance of the coating film tend to be further improved.

4. Recording device FIG. 1 shows an example of a recording device used in the recording method of the present embodiment. As shown in FIG. 1, the recording device 1 includes a feeding unit 10, a transport unit 20, a recording unit 30, a drying unit 90, and a discharging unit 70 of a recording medium.

The feeding unit 10 feeds the roll-shaped recording medium F, which is an example of the recording medium, to the transport unit 20. Specifically, it has a roll medium holder 11, and the roll medium holder 11 holds a roll-shaped recording medium F. By rotating the roll-shaped recording medium F, the recording medium F is fed to the transport unit 20 on the downstream side in the feed direction Y.

The transport unit 20 transports the recording medium F sent from the feed unit 10 to the recording unit 30. Specifically, it has a first feed roller 21 and further conveys the transmitted recording medium F to the recording unit 30 on the downstream side in the feed direction Y.

The recording unit 30 records by ejecting and adhering each ink composition to the recording medium F sent from the transport unit 20. The recording unit 30 is provided with a plurality of inkjet heads, and can eject a plurality of types of ink. In FIG. 1, seven inkjet heads are provided, but one or more inkjet heads may be provided. The platen 35 is a means for supporting the recording medium F from the back surface.

The inkjet head shown in FIG. 1 is a line inkjet head having a length equal to or longer than the recording width in the width direction X of the recording medium F. The inkjet head does not move during recording, and recording is performed by performing one scan in which the processing liquid and the ink composition are ejected from each adhering portion and adhered to the recording medium F while conveying the recording medium F in the Y direction. Perform a 1-pass recording method (line recording method).

In the recording device 1, the inkjet head of the inkjet type ejects the ink composition and the processing liquid while moving in the front-back direction of FIG. 1, that is, in the width direction X of the recording medium F, and the inkjet heads face each other. It may be a serial printer that performs scanning (main scanning) attached to the recording medium F.

A second feed roller 43 is provided on the downstream side of the platen 35 in the feed direction Y. The second feed roller 43 feeds the recorded recording medium F to the second drying unit 50 on the downstream side in the feed direction Y.

The drying unit 90 includes a first drying unit 40 and a second drying unit 50. The first drying unit 40 is a platen heater for primary drying the ink composition adhering to the recording medium F. Examples of the first drying unit 40 include an infrared heater and a heat conductive heating means such as a nichrome wire. The first drying unit 40 may be a device that radiates radiation or a device that blows warm air.

The second drying unit 50 further dries the recording medium to which the ink is attached by heating. The second drying unit 50 is, for example, a blowing mechanism (not shown) that blows air to the recording medium F, a support portion that is in contact with the recording medium F on a surface and the recording medium is conveyed along the surface, and heats the support portion to be conveyed from the support portion to the recording medium. A heat transfer mechanism that transfers heat to F, a radiation irradiation mechanism such as an infrared heater that radiates infrared rays to the recording medium F to heat the recording medium, and the like can be used. A third feed roller 65 is provided in the vicinity of the outlet 64 of the second drying portion 50. The third feed roller 65 is arranged so as to be in contact with the back surface of the recording medium F, and feeds the recording medium F to the discharge unit 70 on the downstream side in the feed direction Y.

The discharging unit 70 further feeds the recording medium F sent from the second drying unit 50 to the downstream side in the feeding direction Y, and discharges the recording medium F to the outside of the inkjet recording device 1. Specifically, the discharge unit 70 includes a fourth feed roller 71, a fifth feed roller 72, a sixth feed roller 73, a seventh feed roller 74, and a take-up roller 75. The fourth feed roller 71 and the fifth feed roller 72 are arranged so as to be in contact with the surface of the recording medium F. The sixth feed roller 73 and the seventh feed roller 74 are arranged so as to form a roller pair. The recording medium F discharged by the 6th feed roller 73 and the 7th feed roller 74 is wound by the take-up roller 75.

The inkjet recording device 1 further includes a control unit (not shown). The control unit controls the feeding unit 10, the transport unit 20, the recording unit 30, the drying unit 90, the drying device 100, the discharging unit 70, and the like when the inkjet recording device 1 records.

The upper limit of the surface temperature of the recording medium F during recording in the region facing the inkjet head is preferably 50 ° C. or lower, more preferably 45 ° C. or lower. The temperature is preferably 25 ° C. or higher, more preferably 30 ° C. or higher, further preferably 35 ° C. or higher, and particularly preferably 40 ° C. or higher. As a result, since the radiant heat received from the drying part or the drying device is small or absent, the ink composition in the inkjet head, drying and composition fluctuation can be suppressed, and the ink can be fixed at an early stage by heating, and the image quality can be improved. Can be improved.

The above temperature is the maximum surface temperature of the portion of the recording medium F facing the inkjet head during recording. When the primary drying is performed by the first drying unit 40, it is the temperature of the primary drying. When the primary drying is not performed, it is the temperature around the recording medium in the portion facing the inkjet head.

The second drying unit 50 is a heater for drying and solidifying the ink adhering to the recording medium F, that is, for secondary heating or secondary drying. When the second drying unit 50 heats the recording medium F on which the image is recorded, the water content contained in the ink evaporates and scatters more quickly, and the resin contained in the ink forms an ink film. .. In this way, the ink film is firmly fixed or adhered on the recording medium F to have excellent film-forming properties, and an excellent high-quality image can be obtained in a short time. The upper limit of the surface temperature of the recording medium F by the second drying unit 50 is preferably 120 ° C. or lower, more preferably 100 ° C. or lower, and even more preferably 90 ° C. or lower. Further, the lower limit of the surface temperature of the recording medium F is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, and even more preferably 80 ° C. or higher. When the temperature is in the above range, a high-quality image can be obtained in a short time. The above temperature is the maximum temperature of the surface of the recording medium F in the secondary drying.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention can be modified in various ways as long as it does not deviate from the gist thereof, and is not limited by the following Examples. ..

<Manufacturing Example 1: Polyester Polyol (a12-1)>
In a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introduction tube, and a thermometer, 770 parts of terephthalic acid, 880 parts of 1,2-prepyrene glycol, and 0.5 part of tetrabutoxytitanate as a polymerization catalyst were charged at 210 ° C. The reaction was carried out for 5 hours while distilling off 1,2-prepyrene glycol with the water produced by the reaction under a nitrogen stream. Then, the reaction was further carried out under a reduced pressure of 5 to 20 mmHg for 1 hour. The obtained resin was cooled to room temperature and then pulverized to obtain 1000 parts of a polyester polyol (a12-1) containing 76% by weight of the structural unit represented by the general formula (3) based on the weight of the polyol. The Mn of (a12-1) was 1500.

<Manufacturing Example 2: Polyester Polyol (a12-2)>
In a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introduction tube, and a thermometer, 498 parts of terephthalic acid, 263 parts of adipic acid, 1400 parts of 3-methyl-1,5-pentanediol, and tetrabutoxytitanate 0 as a polymerization catalyst. .5 parts were charged and reacted at 210 ° C. under a nitrogen stream for 5 hours while distilling off the water produced by the reaction and 3-methyl-1,5-pentanediol. Then, the reaction was further carried out under a reduced pressure of 5 to 20 mmHg for 1 hour. The obtained resin was cooled to room temperature and then pulverized to obtain 1000 parts of a polyester polyol (a12-2) containing 49% by weight of the structural unit represented by the general formula (3) based on the weight of the polyol. The Mn of (a12-2) was 1500.

<Manufacturing example U-1>
In a simple pressurizing reaction device equipped with a stirrer and a heating device, 161.6 parts of NISSO-PBGI-2000 [manufactured by Nippon Soda Co., Ltd.] which is a polyolefin polyol (a11) and neo which is a low molecular weight polyol (a2). 13.2 parts of pentylglycol, 14.6 parts of 2,2-dimethylolpropionic acid which is a compound (a3), 99.9 parts of IPDI which is an organic polyisocyanate component (B), and Neostan U which is a urethanization catalyst. -600 [manufactured by Nitto Kasei Co., Ltd.] 0.07 part and 150.0 parts of methyl ethyl ketone, which is an organic solvent for reaction, were charged, and the mixture was stirred at 80 ° C. for 6 hours to carry out a urethanization reaction, and a urethane pre having an isocyanate group was carried out. A methyl ethyl ketone solution of the polymer (P1) was obtained.

60.6 parts of the polyester polyol (a12-1) obtained in Production Example 1 was charged into the obtained urethane prepolymer (P1), stirred at 80 ° C. for 4 hours to carry out a urethanization reaction, and having an isocyanate group. A methyl ethyl ketone solution of urethane prepolymer (P2) was produced.

Next, 8.3 parts of triethylamine as a neutralizing agent and 74.2 parts of methyl ethyl ketone as an organic solvent for dilution were added to the obtained methyl ethyl ketone solution of the urethane prepolymer (P2) to homogenize the mixture, and then the mixture was stirred at 200 rpm. , The chain extender (a4) and 485.4 parts of water as an aqueous medium were added, and the polyurethane prepolymer (P2) was dispersed in water.

The obtained dispersion was heated to 50 ° C. and stirred for 4 hours to carry out an extension reaction with water, and further heated to 60 ° C. under reduced pressure to distill off methyl ethyl ketone. Then, after cooling the obtained dispersion to room temperature, 23.6 parts of SM8706EX [solid content concentration 37% by mass, manufactured by Toray Dow Corning Co., Ltd.], which is dimethyl silicone, was added to homogenize, and water was further added. An aqueous dispersion of the urethane resin (U-1) was obtained by adjusting the solid content concentration to 30% by mass. The numerical values shown in Table 1 below mean parts by mass unless otherwise specified.

<Manufacturing Examples U-2 to U-4 and U'-1 to U'-2>
Aqueous dispersions of urethane resins (U-2) to (U-4) were obtained in the same manner as U-1 except that the raw materials used and the amounts used were changed to those shown in Table 1.

・ＮＩＳＳＯ－ＰＢ ＧＩ－２０００：Ｍｎ＝２０００の水添ポリブタジエンジオール［日本曹達（株）製］；一般式（１）におけるＲ１がエチル基である構成単位を有する。
・ＮＩＳＳＯ－ＰＢ Ｇ－２０００：Ｍｎ＝１９００のポリブタジエンジオール［日本曹達（株）製］；一般式（１）におけるＲ１がビニル基である構成単位を有する。
・クラレポリオールＰ－２０１０：Ｍｎ＝２０００のポリ３－メチル－ペンタメチレンアジペート［クラレ（株）製］
・サンニックスＰＰ－２０００：Ｍｎ＝２０００のポリオキシプロピレンジオール［三洋化成工業（株）製］
・ネオスタンＵ－６００：ビスマストリス（２－エチルへキサノエート）［日東化成（株）製］
・ＳＭ８７０６ＥＸ：ジメチルシリコーンの水性エマルション（固形分濃度３７重量％）［東レ・ダウコーニング（株）製］
・ＰＯＬＯＮ ＭＦ－３２：ジメチルシコーンの水性エマルション（固形分濃度３１重量％）［信越化学（株）製］

NISSO-PB GI-2000: Hydrogenated polybutadiene diol with Mn = 2000 [manufactured by Nippon Soda Co., Ltd.]; It has a structural unit in which R1 in the general formula (1) is an ethyl group.
NISSO-PB G-2000: Polybutadiene diol with Mn = 1900 [manufactured by Nippon Soda Co., Ltd.]; It has a structural unit in which R1 in the general formula (1) is a vinyl group.
-Kuraray Polyol P-2010: Poly3-methyl-pentamethylene adipate with Mn = 2000 [manufactured by Kuraray Co., Ltd.]
-Sannicks PP-2000: Polyoxypropylene diol with Mn = 2000 [manufactured by Sanyo Chemical Industries, Ltd.]
-Neostan U-600: Bismuth Tris (2-ethylhexanoate) [manufactured by Nitto Kasei Co., Ltd.]
SM8706EX: Aqueous emulsion of dimethyl silicone (solid content concentration 37% by weight) [manufactured by Toray Dow Corning Co., Ltd.]
-POLON MF-32: Aqueous emulsion of dimethyl corn (solid content concentration 31% by weight) [manufactured by Shin-Etsu Chemical Co., Ltd.]

<Manufacturing Example F: Preparation of Urethane Resin (F)>
In a reaction vessel containing a stirrer, a reflux condenser and a thermometer, 200 g of polytetramethylene glycol (PTMG2000 manufactured by Mitsubishi Chemical Co., Ltd .: number average molecular weight 2000), 30 g of 2,2-dimethylolpropionic acid (DMPA) and bisphenoxyethanol fluorene (Osaka). 31 g of gas chemical) and 130 g of methyl ethyl ketone (MEK: bp79.6 ° C.) were charged under a nitrogen stream and heated to 65 ° C. to dissolve DMPA. 190 g of 4,4'-dicyclohexylmethane diisocyanate (MCHDI) and 0.26 g of urethanization catalyst XK-614 (manufactured by Kusumoto Kasei) were added and heated to 75 ° C., and the urethanization reaction was carried out over 5 hours. Obtained a polymer.

Next, the reaction mixture was cooled to 70 ° C., and 40 g of triethanolamine was added to the mixture. Then, 690 g of the entire amount was extracted from the mixture, and the mixture was put into a mixed solution of 540 g of water and 40 g of triethanolamine under strong stirring. added. Then, 160 g of ice was added, 110 g of a 35 mass% bicycloheptane dimethaneamine aqueous solution was added to carry out a chain extension reaction, and a part of methyl ethyl ketone and water was distilled off so that the solid content concentration became 30%, and a urethane resin was added. An aqueous dispersion of (F) (urethane resin component 30%, water 70%, acid value 26 mgKOH / g) was obtained.

<Manufacturing Example A: Preparation of Urethane Resin (A)>
In the production of urethane resin (F), polytetramethylene glycol (polytetramethylene glycol) is used instead of 190 g of 4,4'-dicyclohexylmethane diisocyanate (MCHDI) instead of 190 g of bisphenoxyethanol fluorene. Urethane resin (A) (urethane resin component 30%) except that 330 g of polyester polyol (Polylite OD-X-2420 made by DIC: molecular weight 2000) was used instead of 200 g of Mitsubishi Chemical PTMG2000: number average molecular weight 2000). , 70% water, acid value 22 mgKOH / g) was obtained.

<Preparation of clear ink composition>
The components shown in Table 2 below were sufficiently stirred and then subjected to vacuum filtration with a microfilter (manufactured by Millipore) having a pore size of 5.0 μm to prepare a clear ink composition. The values shown in Table 2 below mean% by mass unless otherwise specified. Emulsions such as resins and waxes are the mass of their solid content. The silicone emulsion is the sum of the one contained in the urethane resin dispersion and the one added at the time of ink preparation. In addition, "CL" means that it is a clear ink.

・ＳＭ８７０６ＥＸ：ジメチルシリコーンの水性エマルション（固形分濃度３７重量％）
［東レ・ダウコーニング（株）製］
・ＰＯＬＯＮ ＭＦ－３２：ジメチルシコーンの水性エマルション（固形分濃度３１重量％）［信越化学（株）製］
・ＡＱＵＡＣＥＲ１５４７：ポリオレフィンワックスの水性エマルジョン（固形分濃度３５重量％）［ＢＹＫ社製］
・オルフィンＰＤ５０１：アセチレン系界面活性剤［日信化学工業社製］

SM8706EX: Aqueous emulsion of dimethyl silicone (solid content concentration 37% by weight)
[Made by Toray Dow Corning Co., Ltd.]
-POLON MF-32: Aqueous emulsion of dimethyl corn (solid content concentration 31% by weight) [manufactured by Shin-Etsu Chemical Co., Ltd.]
AQUACER1547: Aqueous emulsion of polyolefin wax (solid content concentration 35% by weight) [manufactured by BYK]
Orfin PD501: Acetylene-based surfactant [manufactured by Nissin Chemical Industry Co., Ltd.]

<Preparation of colored ink composition>
After sufficiently stirring the components shown in Table 3 below, vacuum filtration was performed with a microfilter (manufactured by Millipore) having a pore size of 5.0 μm to prepare clear ink compositions of Examples and Comparative Examples. As for the pigment, a dispersant which is a styrene acrylic water-soluble resin (not shown in the table) is mixed with water in an amount of 1: 0.5 part by mass with respect to the pigment and stirred. A pigment dispersion was prepared and used. The values shown in Table 3 below mean% by mass unless otherwise specified. Pigments, resins, etc. are the mass of their solid content. The silicone emulsion is the sum of the one contained in the urethane resin dispersion and the one added at the time of ink preparation. In addition, "C" means that it is a color ink, and "W" means that it is a white ink.

・アクリル系樹脂：スチレン－アクリル系樹脂、アルマテックスＥ２０８［三井化学社製］
・ＳＭ８７０６ＥＸ：ジメチルシリコーンの水性エマルション（固形分濃度３７重量％）
［東レ・ダウコーニング（株）製］
・ＰＯＬＯＮ ＭＦ－３２：ジメチルシコーンの水性エマルション（固形分濃度３１重量％）［信越化学（株）製］
・ＡＱＵＡＣＥＲ１５４７：ポリオレフィンワックスの水性エマルジョン（固形分濃度３５重量％）［ＢＹＫ社製］
・オルフィンPD501：アセチレン系界面活性剤［日信化学工業社製］

-Acrylic resin: Styrene-acrylic resin, Almatex E208 [manufactured by Mitsui Chemicals, Inc.]
SM8706EX: Aqueous emulsion of dimethyl silicone (solid content concentration 37% by weight)
[Made by Toray Dow Corning Co., Ltd.]
-POLON MF-32: Aqueous emulsion of dimethyl corn (solid content concentration 31% by weight) [manufactured by Shin-Etsu Chemical Co., Ltd.]
AQUACER1547: Aqueous emulsion of polyolefin wax (solid content concentration 35% by weight) [manufactured by BYK]
-Orphin PD501: Acetylene-based surfactant [manufactured by Nisshin Kagaku Kogyo Co., Ltd.]

<Evaluation test>
For the evaluation test, as an inkjet recording type printer, a modified inkjet printer PX-G930 (manufactured by Seiko Epson Corporation, nozzle resolution: 180 dpi) with a heater that can change the temperature was used.

Next, using the clear ink, cyan ink, and white ink shown in Tables 2 to 3, an ink set including the clear ink and the color ink or the white ink was obtained. Then, each ink set was filled in the ink cartridge, and the ink cartridge was attached to the inkjet printer.

Then, using the inkjet printer, the image was printed and dried on an A4 size recording medium (OPP Toyobo Pyren P2102). Specifically, first, cyan ink or white ink was ejected under printing conditions: resolution 1440 × 1440 dpi, 100% duty, and adhesion amount 5.5 mg / inch ² , and these inks were adhered to a recording medium. Then, about 20 seconds after the adhesion, the clear ink was ejected and adhered to the same area of the recording medium under the printing conditions: resolution 1440 × 1440 dpi, 100% duty, and adhesion amount 5.5 mg / inch ² . As a result, a solid pattern image in which the clear ink composition was adhered was formed on the colored ink composition. The adhered ink was dried by a platen heater (45 ° C.) provided in the printer. Then, the obtained image was dried in a constant temperature bath at 80 ° C. for 10 minutes. In this way, a sample for scratch resistance evaluation on which a cyan or white solid pattern image was printed was obtained.

Further, the recording medium was changed to PET (Toyobo Espet E-5102), and the same recording was performed to obtain a sample for scratch resistance evaluation.

<Dry rubbing resistance>
As described above, the Gakushin type friction fastness tester (Tester Sangyo Co., Ltd. AB-301) is used for each sample image (recording pattern part) of the sample using OPP as the recording medium and the sample using PET as the recording medium. A weight of 200 g is applied to a dry white cotton cloth for rubbing, and the cloth is rubbed 100 times at a reciprocating speed of 30 times per minute. Was evaluated.
(Evaluation criteria)
A: No peeling of solid image is observed B: Peeling is observed in more than 0 area% of solid image and less than 10 area% C: Peeling is observed in 10 area% or more and less than 50 area% of solid image D: Solid image Peeling is observed in 50 area% or more and 100 area% or less of the image.

<Wet and scratch resistant>
Similarly, the image (recording pattern part) is moistened with water using a Gakushin type friction fastness tester (Tester Sangyo Co., Ltd. AB-301) and moistened to about 100% by mass with respect to the cloth. Was rubbed 10 times at a reciprocating speed of 30 times per minute with a load of 200 g, and visually observed to evaluate "wet abrasion resistance" based on the following evaluation criteria.
(Evaluation criteria)
A: No peeling of solid image is observed B: Peeling is observed in more than 0 area% of solid image and less than 10 area% C: Peeling is observed in 10 area% or more and less than 50 area% of solid image D: Solid image Peeling is observed in 50 area% or more and 100 area% or less of the image.

<Recovery against clogging>
The obtained clear ink composition was filled in the inkjet printer, and it was confirmed that the ink was ejected by all the nozzles. Then, it was left for 2 days in an environment of a temperature of 40 ° C. and a relative humidity of 20%. After being left to stand, the clear ink composition was ejected from all the nozzles, cleaning was repeated until printing equivalent to the initial printing was possible, and the number of cleanings at that time was measured. Based on the number of cleanings, clogging recovery was evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: The ink composition was ejected from all the nozzles by cleaning 1 to 3 times.
B: The ink composition was ejected from all the nozzles by cleaning 4 to 6 times.
C: There was a nozzle that did not eject even after cleaning 6 times. When the test was performed again with the standing period changed from 2 days to 1 day, the ink composition was ejected from all the nozzles by cleaning 1 to 3 times.
D: There was a nozzle that was not ejected even after 6 cleanings. When the test was performed again after changing the leaving period from 2 days to 1 day, some nozzles were not ejected even after cleaning 1 to 3 times.

<Evaluation result>
As described above, in each of the examples using the clear ink containing the urethane resin (U), the coating film has dry and wet resistance to a wide range of recording media from polar recording media to low-polarity recording media. It turns out that it is excellent in sex. On the other hand, in Comparative Examples 1 to 3 using a clear ink containing a urethane resin other than the urethane resin (U), either the dry rubbing resistance or the wet rubbing resistance is inferior, or the dry rubbing resistance is reduced. The result was that both wet and scratch resistance were inferior. Further, even in Comparative Example 5 in which the clear ink composition was not used, both the dry rubbing resistance and the wet rubbing resistance were inferior.

Further, in Reference Example 1 in which the colored ink C2 in which the urethane resin (U) is contained in the colored ink composition is used without using the clear ink composition, a wide range of recording media from polar recording media to low-polarity recording media can be used. It was found that although the dry rubbing resistance and the wet rubbing resistance were excellent, the clogging recovery was inferior.
On the other hand, in Reference Example 1 in which the colored ink C3 in which the urethane resin (A) is contained in the colored ink composition is used without using the clear ink composition, although the clogging recovery can be ensured, the dry rubbing resistance and the wettability can be ensured. It was found that the improvement of scratch resistance was insufficient.

1 ... Recording device, 10 ... Feeding section, 11 ... Roll medium holder, 20 ... Transport section, 21 ... First feed roller, 30 ... Recording section, 35 ... Platen, 40 ... First drying section, 43 ... Second feed Roller, 50 ... 2nd drying part, 70 ... Discharge part, 71 ... 4th feed roller, 72 ... 5th feed roller, 73 ... 6th feed roller, 74 ... 7th feed roller, 75 ... Take-up roller, 90 ... Drying part, 100 ... Drying device, F ... Recording medium

Claims (14)

A water-based clear ink composition containing a resin.
A urethane resin (U) having a structure derived from an active hydrogen component (A) containing a polymer polyol component (a1) having a number average molecular weight of 500 or more and an organic polyisocyanate component (B). Including,
The polymer polyol component (a1) has a structural unit represented by the general formula (1) and / or a structural unit represented by the general formula (2), and a structural unit represented by the general formula (3). Have,
Clear ink composition.

(In the formula (1), R ¹ represents a hydrogen atom, a methyl group, an ethyl group, a vinyl group, an isopropyl group or an isopropenyl group, and R ² represents a hydrogen atom or a methyl group.)

(In formula (2), R ³ represents a hydrogen atom or a methyl group.)

It does not have at least one of the structural unit represented by the general formula (1) and / or the structural unit represented by the general formula (2) and the structural unit represented by the general formula (3), and is a fluorene group. Further contains a urethane resin (F) having a structural unit having
The clear ink composition according to claim 1. It has a fluorene group with at least one of the structural unit represented by the general formula (1) and / or the structural unit represented by the general formula (2) and the structural unit represented by the general formula (3). It does not have a constituent unit,
and,
Further containing a urethane resin (A) having a composition derived from any of m-bis (isocyanate propyl) benzene, m-bis (isocyanate methyl) benzene, tolylene diisocyanate, or 4,4-diphenylmethane diisocyanate.
The clear ink composition according to claim 1 or 2. The content of the urethane resin (U) with respect to the total amount of the clear ink composition is equal to or greater than the content of the urethane resin (A) with respect to the total amount of the clear ink composition.
The clear ink composition according to claim 3. The content of the urethane resin (U) is 2 to 20% by mass with respect to the total amount of the clear ink.
The clear ink composition according to any one of claims 1 to 4. Containing at least one of a silicone emulsion or a polyolefin wax emulsion,
The clear ink composition according to any one of claims 1 to 5. It is used for recording that is attached to a recording medium by the inkjet method.
The clear ink composition according to any one of claims 1 to 6. It is used for recording on a polar recording medium and recording on a low-polarity recording medium.
The clear ink composition according to any one of claims 1 to 7. The clear ink composition according to any one of claims 1 to 8.
A water-based coloring ink composition containing a coloring material.
Ink set. The colored ink composition contains at least one of an acrylic resin, a urethane resin, and a polyester resin.
The ink set according to claim 9. The colored ink composition comprises a white ink containing a white colorant.
The ink set according to claim 9 or 10. A clear ink adhering step for adhering the clear ink composition according to any one of claims 1 to 8 to a recording medium is provided.
Recording method. The clear ink adhesion step is performed by an inkjet method.
A colored ink adhering step of adhering a water-based colored ink composition containing the coloring material according to any one of claims 9 to 11 to the recording medium by an inkjet method is provided.
The recording method according to claim 12. In a recording device for recording on a polar recording medium and recording on a low-polarity recording medium using the clear ink composition, the recording is performed on a polar recording medium or a low-polarity recording medium.
The recording method according to claim 12 or 13.

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