JP2011168736A - Photocurable ink composition and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation curable ink composition being excellent in scratch resistance and adhesion properties. <P>SOLUTION: The radiation curable ink composition contains a radical polymerizable compound, a photoinitiator and urethane wax. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photocurable ink composition and an ink jet recording method.

  Conventionally, various recording methods are used as an image recording method for forming an image on a recording medium such as paper based on an image data signal. Among these, the ink jet recording method is an inexpensive apparatus that ejects ink only to a required image portion and directly forms an image on a recording medium. Therefore, the ink can be used efficiently and the running cost is low. Furthermore, the ink jet recording method is excellent as an image recording method because of low noise.

  In recent years, when printing on the surface of a plastic non-absorbable recording medium, a photocurable ink jet recording ink that contains a radical polymerizable compound and a photopolymerization initiator and cures when irradiated with electromagnetic waves such as ultraviolet rays has been developed. in use.

  For example, Patent Document 1 discloses an ultraviolet curable ink composition using an acrylic acid ester and N-vinylcaprolactam as radically polymerizable compounds.

International Publication No. 07/097049

  However, the cured film of the ink composition disclosed in Patent Document 1 is inferior in scratch resistance, and as a result, there is a problem that the rubbed portion disappears when the image is rubbed. In addition, when the above ink composition is printed on the surface of a non-absorbable recording medium made of plastic, the adhesiveness is inferior, so that it becomes difficult to print on a desired portion, or an image can be easily printed even once printed. There is a problem of disappearing.

  Accordingly, an object of the present invention is to provide a photocurable ink composition and an ink jet recording method that are excellent in scratch resistance and adhesion.

  The present inventors have intensively studied to solve the above problems. As a result, in addition to radical polymerizable compounds and photopolymerization initiators including monomers such as acrylic acid esters and N-vinylcaprolactam and oligomers such as urethane acrylate and polyester acrylate, urethane wax is contained in the ink composition. The inventors have found that a photocurable ink composition excellent in scratch resistance and adhesion can be obtained, and completed the present invention.

That is, the present invention is as follows.
[1]
A photocurable ink composition comprising a radical polymerizable compound, a photopolymerization initiator, and a urethane wax.
[2]
The photocurable ink composition according to [1], which includes 0.5 to 10% by mass of the urethane wax with respect to 100% by mass of the ink composition.
[3]
The photopolymerizable ink composition according to [1] or [2], wherein the radical polymerizable compound includes one or more selected from the group consisting of phenoxyethyl acrylate, isobornyl acrylate, and N-vinylcaprolactam.
[4]
[1] to [3] The photocurable ink composition according to any one of [3] to a printing process for printing on a recording medium by an inkjet method, and the ink composition printed by the printing process to 360 to A curing step of curing by irradiation of a light emitting diode having a peak wavelength in the range of 400 nm.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not restrict | limited to the following embodiment, A various deformation | transformation can be implemented within the range of the summary.

[Photocurable ink composition]
One embodiment of the present invention relates to a photocurable ink composition. The photocurable ink composition includes a radical polymerizable compound, a photopolymerization initiator, and urethane wax as a slip agent.

  Hereinafter, components contained in the photocurable ink composition according to this embodiment (hereinafter also simply referred to as “ink composition”) will be described.

[Slip agent]
The ink composition of the present embodiment can form a cured film having excellent scratch resistance and adhesion by including urethane wax as a slip agent. Moreover, the ink composition is excellent in flexibility and storage stability is also good.
Here, the “urethane wax” in the present specification refers to a compound (urethane product) obtained by reacting an isocyanate compound and an alkyl alcohol.

The urethane wax may be either non-reactive or reactive urethane wax. As non-reactive urethane waxes include, but are not limited to, chemical formula C ₁₈ H ₃₇ compounds represented by _{NCOOC n H (2n + 1)} (n is an integer of 4 to 16) are exemplified.

On the other hand, the reactive urethane wax is not particularly limited, and examples thereof include those having one or more functional groups having reactivity with (meth) acrylate compounds. More specifically, as an example of a reactive urethane waxes, chemical formula _{C n H (2n + 1)} NC (O) OC m H (2m) OC (O) C (CH 3) = compound represented by CH ₂ (N is an integer of about 12 to about 18, and m is an integer of about 2 to about 12.). Other examples of reactive urethane waxes, chemical formula _{C n H (2n + 1)} O (O) CNC 2 H 4 OOCC (CH 3) = compound represented by CH ₂ (n is from about 4 to about 18 Integer).

  The urethane wax is preferably contained in an amount of 0.5 to 10% by mass, more preferably 1 to 5% by mass with respect to 100% by mass of the ink composition. When the content of the urethane wax is 0.5% by mass or more, the scratch resistance of a cured film (hereinafter also referred to as “coating film”) obtained by curing the ink composition is further improved. On the other hand, when the content of the urethane wax is 10% by mass or less, the flexibility of the coating film and the storage stability of the ink composition are further improved.

  The urethane wax is preferably at least one of 1-dodecyl-N-octadecylcarbamate and 1-hexadecyl-N-octadecylcarbamate, and more preferably a combination of these compounds. As 1-dodecyl-N-octadecylcarbamate, a product marketed under the trade name “ADS038” is available, and as 1-hexadecyl-N-octadecylcarbamate, a product marketed under the trade name “ADS043” is available. These are all manufactured by American Dye Source, Inc. (Bayederph, Quebec, Canada).

[Radically polymerizable compound]
The ink composition of this embodiment is printed by a chain reaction of a radically polymerizable compound, which is a component of the composition, with a photopolymerization initiator radical described later generated by light irradiation of a specific wavelength (range). Cure on media. The radical polymerizable compound has a structure in which a group selected from the group consisting of acryloyl group, methacryloyl group, acrylamide group, vinyl group, vinylamino group, vinyl ether group, vinyl thioether group, propenyl group, and vinylidene group is 1 in the structure. One having at least one and having an acryloyl group and a methacryloyl group in the structure is preferable, particularly an acryloyl group is preferable, and monomers having a monomer and a dimer to an oligomer having a molecular weight or a molecular weight of about several thousand. Including.

Specific examples of the monomer of the radical polymerizable compound include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid and esters thereof, styrene derivatives such as styrene, vinyltoluene and dimethylstyrene, Examples include N-vinyl compounds such as N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylformamide, N-vinylacetamide, N-substituted maleimides, acrylonitrile, acryloylmorpholine, and the like.
Specific examples of the oligomer of the radical polymerizable compound include polyester acrylate, polyurethane acrylate, epoxy acrylate, polyether acrylate, oligo acrylate, alkyd acrylate, polyol acrylate, polyester methacrylate, polyurethane methacrylate, epoxy methacrylate, polyether methacrylate, oligo methacrylate, Examples include alkyd methacrylate and polyol methacrylate.

  Among these, acrylic acid esters having an acryloyl group, an N-vinyl compound, and acryloylmorpholine are preferable because of excellent photopolymerizability.

  Examples of monofunctional acrylic acid esters include isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isomyristyl acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol acrylate, 2-hydroxybutyl acrylate, butoxyethyl. Acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy 3-phenoxypropyl acrylate, lactone-modified flexible acrylate, t- butyl cyclohexyl acrylate, dicyclopentenyl acrylate, dicyclopentenyl oxyethyl acrylate, and the like isobornyl acrylate.

  Examples of the bifunctional acrylate ester include triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1, 6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate, EO (ethylene oxide) adduct diacrylate of bisphenol A, PO (propylene oxide) of bisphenol A ) Adduct diacrylate, hydroxypivalate neopentyl glycol diacrylate, and polytetramethylene glycol diacrylate Acrylate, and the like.

  Examples of the tri- or higher functional acrylic ester include trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxy Examples include triacrylate, caprolactone-modified trimethylolpropane triacrylate, pentaerythritol ethoxytetraacrylate, and caprolactam-modified dipentaerythritol hexaacrylate.

Furthermore, in order to further improve the flexibility of the cured coating film of the ink, it is preferable to use a monomer (monomer) whose homopolymer has a glass transition point of room temperature (25 ° C.) or less. As a monomer (monomer) having a glass transition point (Tg) of a homopolymer of room temperature (25 ° C.) or less, for example, phenoxyethyl acrylate (Tg: −22 ° C.), phenoxydiethylene glycol acrylate (Tg: −25 ° C.) , Isoamyl acrylate (Tg: −45 ° C.), lauryl acrylate (Tg: −30 ° C.), ethoxydiethylene glycol acrylate (Tg: −50 ° C.), tetrahydrofurfuryl acrylate (Tg: −15 ° C.), isodecyl acrylate (Tg: -60 ° C), isooctyl acrylate (Tg: -54 ° C), tridecyl acrylate (Tg: -55 ° C), caprolactone acrylate (Tg: -53 ° C), and the like.
Generally, in polymer solids, especially amorphous polymer solids, when the temperature is raised from a low temperature to a high temperature, a state where a large amount of deformation occurs with a small force from a state where a very large force is required for slight deformation (glass state). The temperature at which this phenomenon occurs is called the glass transition temperature (or glass transition point). Generally, in the differential heat curve obtained by temperature rise measurement with a differential scanning calorimeter, the intersection of the base line when the tangent line is drawn from the bottom of the endothermic peak toward the end point of the endotherm. The temperature is taken as the glass transition temperature. Tg in this specification follows this definition. In addition, it is known that other physical properties such as elastic modulus, specific heat, and refractive index change abruptly at the glass transition temperature, and it is known that the glass transition temperature is also determined by measuring these physical properties. ing.

Said radically polymerizable compound may be used individually by 1 type, and may use 2 or more types together.
Among the monofunctional monomers, phenoxyethyl acrylate is preferable because of its low viscosity (3 to 5 mPa · s), excellent compatibility with monomers and oligomers, and excellent solubility of the photopolymerization initiator.
Moreover, the monofunctional monomer which has a bulky structure in a structure from the point of giving toughness to a coating film is preferable, and isobornyl acrylate, dicyclopentenyl acrylate, and dicyclopentenyl oxyethyl acrylate are more preferable.

Furthermore, by properly selecting phenoxyethyl acrylate, isobornyl acrylate, dicyclopentenyl acrylate, and dicyclopentenyl oxyethyl acrylate and controlling the composition ratio, the properties of the coating are strong and a wide range from rigid to flexible Characteristics can be obtained. The performance of such a coating film is suitably in the range of 10-50% by mass of phenoxyethyl acrylate, 10-50% by mass of isobornyl acrylate, dicyclopentenyl acrylate and dicyclopentenyloxyethyl acrylate. It can be obtained by adjusting the ratio. For example, a flexible coating film can be obtained by setting phenoxyethyl acrylate to 30 to 50% by mass and isobornyl acrylate, dicyclopentenyl acrylate and dicyclopentenyloxyethyl acrylate to 10 to 30% by mass.
The bifunctional monomer dimethylol tricyclodecane diacrylate has a bulky structure and two acryloyl groups in its structure, so it is tough and has excellent water resistance, chemical resistance and heat resistance. Is preferable.

  The ink composition of the present embodiment preferably contains an N-vinyl compound. By containing the N-vinyl compound, the cured coating film of the ink composition has excellent adhesion to plastics such as polyvinyl chloride, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, ABS, and polystyrene. Of the N-vinyl compounds, N-vinylcaprolactam is more preferable because it is excellent in adhesion to plastics and is excellent in photopolymerization and hardly increases in ink viscosity when added. N-vinylcaprolactam is contained in the ink composition in an amount of 1 to 10% by mass, preferably 1 to 5% by mass. If the N-vinylcaprolactam contained in the ink composition is less than 1% by mass, the adhesiveness is poor, and if it exceeds 10% by mass, the coating film may turn yellow.

As described above, the radical polymerizable compound preferably contains one or more selected from the group consisting of phenoxyethyl acrylate, isobornyl acrylate, and N-vinylcaprolactam.
The radically polymerizable compound is preferably contained in the ink composition in an amount of 70 to 90% by mass.

The radical polymerizable compound preferably contains urethane acrylate. The urethane acrylate may be monofunctional or bifunctional or more polyfunctional. Urethane acrylate is preferable because a flexible and tough coating film can be obtained from a highly elastic, high hardness and tough coating film because of its structure.
The cured film of the ink composition formed on the surface of the non-absorbable recording medium made of plastic tends to peel off from the recording medium or cause cracks. These occur as a result of poor toughness (toughness) of the cured film of the ink composition. Therefore, when the ink composition contains urethane acrylate, a cured film with improved toughness (toughness) can be formed, and peeling and cracking from the recording medium can be suppressed.

  The urethane acrylate is preferably contained in the ink composition in an amount of 0.5 to 5% by mass, more preferably 1 to 3% by mass. When the content of urethane acrylate is in the range of 0.5 mass% or more and less than 5 mass%, the cured coating film of the ink becomes tough and the abrasion resistance is improved. Also, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, ABS Adhesion to plastics such as polystyrene is improved. On the other hand, when the content of the urethane acrylate is 5% by mass or more, the viscosity of the ink tends to increase rapidly as the content increases, so that it is difficult to use for inkjet.

(Photopolymerization initiator)
The photopolymerization initiator contained in the ink composition of the present embodiment is an uncured ink composition printed by an ink jet recording apparatus on the surface of a recording medium such as a plastic film or board by photopolymerization caused by ultraviolet irradiation. Used to cure objects. As the photopolymerization initiator, a known radical photopolymerization initiator can be used.

  The radical photopolymerization initiator is not particularly limited, and examples thereof include aromatic ketones, acylphosphine compounds, aromatic onium salt compounds, organic peroxides, thio compounds, hexaarylbiimidazole compounds, and ketoxime ester compounds. , Borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon halogen bond, and alkylamine compounds.

  Specific examples of the photo radical polymerization initiator include acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, benzophenone, 2-chlorobenzophenone, p, p′-dichlorobenzophenone, p, p′-bisdiethylaminobenzophenone. Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-propyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzyl methyl ketal, 2,2-dimethoxy-1,2- Diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] Nyl} 2-methylpropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-dimethylamino-2- (4-methylbenzyl) -1- ( 4-morpholin-4-yl-phenyl) butan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2, 6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] 2-morpholinopropan-1-one, thioxanthone, 2-chlorothioxanthone, 2 -Hydroxy-2-methyl-1-phenyl-1-one, 1- (4-isopropylphenyl) -2 Hydroxy-2-methylpropan-methylbenzoyl fill formate, azo-bis-isobutyronitrile Lilo nitrile, benzoyl peroxide, di -tert- butyl peroxide, and the like.

  Examples of commercially available photo radical polymerization initiators include IRGACURE 651 (2,2-dimethoxy-1,2-diphenylethane-1-one), IRGACURE 184 (1-hydroxy-cyclohexyl-phenyl-ketone), DAROCUR 1173. (2-hydroxy-2-methyl-1-phenyl-propan-1-one), IRGACURE 2959 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane- 1-one), IRGACURE 127 (2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl] -2-methyl-propan-1-one}, IRGACURE 907 (2-Methyl-1- (4-methylthiophenyl) -2-morphol Linopropan-1-one), IRGACURE 369 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1), IRGACURE 379 (2- (dimethylamino) -2-[(4- Methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone), DAROCUR TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide), IRGACURE 819 (bis (2, 4,6-trimethylbenzoyl) -phenylphosphine oxide), IRGACURE 784 (bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole-1-) Yl) -phenyl) titanium), IRGACURE OXE 01 (1.2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)]), IRGACURE OXE 02 (ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime)), IRGACURE 754 (oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2- (Mixture of (2-hydroxyethoxy) ethyl ester) (manufactured by Ciba Japan KK), DETX-S (2,4-diethylthioxanthone) (Nippon Kayaku Co., Ltd. )), Lucirin TPO, LR8883, LR8970 (above, manufactured by BASF), and Ubekrill P36 (manufactured by UCB) It is below.

  A photoinitiator may be used individually by 1 type and may be used in combination of 2 or more type. The ink composition preferably contains 1 to 20% by mass, more preferably 3 to 10% by mass of a photopolymerization initiator based on the total amount. When it is within the above range, good curability can be obtained.

[Color material]
The ink composition of the present embodiment may further include a color material. The coloring material is selected from pigments and dyes, but it is preferable to use pigments from the viewpoint of light resistance.

(Pigment)
In this embodiment, the light resistance of the ink composition can be improved by using a pigment as the color material. As the pigment, both inorganic pigments and organic pigments can be used. The ink composition preferably contains 1 to 10% by mass of the color material, and more preferably 1 to 5% by mass.

  As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, iron oxide, and titanium oxide can be used.

  Organic pigments include insoluble azo pigments, condensed azo pigments, azo lakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Polycyclic pigments, dye chelates (for example, basic dye chelates, acid dye chelates, etc.), dye rakes (basic dye rakes, acid dye rakes), nitro pigments, nitroso pigments, aniline black, daytime A photofluorescent pigment is mentioned. The said pigment may be used individually by 1 type, and may use 2 or more types together.

  More specifically, as an inorganic pigment used for black, the following carbon black, for example, No. manufactured by Mitsubishi Chemical Corporation is used. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, or No2200B, etc .; Columbia Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc .; Cabot Regal 400R, Regal 330R, Regal 660L, Monal 660R 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc .; or Color Black FW1, Color Black FW2, Bck, Col Black FW2, Cck W200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, or Special Black 4 and the like.

  Yellow organic pigments include CIPigment Yellow 1, CIPigment Yellow 2, CIPigment Yellow 3, CIPigment Yellow 4, CIPigment Yellow 5, CIPigment Yellow 6, CIPigment Yellow 7, CIPigment Yellow 10, CIPigment Yellow 11 , CIPigment Yellow 12, CIPigment Yellow 13, CIPigment Yellow 14, CIPigment Yellow 16, CIPigment Yellow 17, CIPigment Yellow 24, CIPigment Yellow 34, CIPigment Yellow 35, CIPigment Yellow 37, CIPigment Yellow 53 , CIPigment Yellow 55, CIPigment Yellow 65, CIPigment Yellow 73, CIPigment Yellow 74, CIPigment Yellow 75, CIPigment Yellow 81, CIPigment Yellow 83, CIPigment Yellow 93, CIPigment Yellow 94, CIPigment Yellow 95 , CIPigment Yellow 97, CIPigment Yellow 98, CIPigment Yellow 99, CIPigment Yellow 108, CIPigment Yellow 109, CIPigment Yellow 110, CIPigment Yellow 113, CIPigment Yellow 114, CIPigment Yellow 117, CIPigment Yellow 120 , CIPigment Yellow 124, CIPigment Yellow 128, CIPigment Yellow 129, CIPigment Yellow 133, CIPigment Yellow 138, CIPigment Yellow 139, CIPigment Yellow 147, CIPigment Yellow 151, CIPigment Yellow 153, CIPigment Yellow 154, CIPigment Yellow 167, CIPigment Yellow 172, CIPigment Yellow 180 mag.

  As magenta organic pigments, CIPigment Red 1, CIPigment Red 2, CIPigment Red 3, CIPigment Red 4, CIPigment Red 5, CIPigment Red 6, CIPigment Red 7, CIPigment Red 8, CIPigment Red 9 , CIPigment Red 10, CIPigment Red 11, CIPigment Red 12, CIPigment Red 14, CIPigment Red 15, CIPigment Red 17, CIPigment Red 17, CIPigment Red 18, CIPigment Red 19, CIPigment Red 21, , CIPigment Red 22, CIPigment Red 23, CIPigment Red 30, CIPigment Red 31, CIPigment Red 32, CIPigment Red 38, CIPigment Red 40, CIPigment Red 41, CIPigment Red 42 , CIPigment Red 48 (Ca), CIPigment Red 48 (Mn), CIPigment Red 57 (Ca), CIPigment Red 57: 1, CIPigment Red 88, CIPigment Red 112, CIPigment Red 114, CIPigment Red 122, CIPigment Red 123, CIPigment Red 144, CIPigment Red 146, CIPigment Red 149, CIPigment Red 150, CIPigment Red 166, CIPigment Red 168, CIPigment Red 170, CIPigment Red 171, CIPigment Red 175, CI .Pigment Red 176, CIPigment Red 177, CIPigment Red 178, CIPigment Red 179, CIPigment Red 184, CIPigment Red 185, CIPigment Red 187, CIPigment Red 202, CIPigment Red 209, CIPigment Red 219, CIPigment Red 224, CIPigment Red 245, or CIPigment Violet 19, CIPigment Violet 23, CIPigment Violet 32, CIPigment Violet 33, CIPigment Violet 36, CIPigment Violet 38, CIPigment Violet 43, CIPigment Violet 50 Etc.

  CIPigment Blue 1, CIPigment Blue 2, CIPigment Blue 3, CIPigment Blue 15, CIPigment Blue 15: 1, CIPigment Blue 15: 2, CIPigment Blue 15: 3, CIPigment Blue 15:34, CIPigment Blue 15: 4, CIPigment Blue 16, CIPigment Blue 18, CIPigment Blue 22, CIPigment Blue 25, CIPigment Blue 60, CIPigment Blue 65, CIPigment Blue 66, CIVat Blue 4 , CIVat Blue 60 and the like.

  Examples of organic pigments other than magenta, cyan and yellow include CIPigment Green 7, CIPigment Green 10, CIPigment Brawn 3, CIPigment Brawn 5, CIPigment Brawn 25, CIPigment Brawn 26, CIPigment Orange 1 , CIPigment Orange 2, CIPigment Orange 5, CIPigment Orange 7, CIPigment Orange 13, CIPigment Orange 14, CIPigment Orange 15, CIPigment Orange 16, CIPigment Orange 24, CIPigment Orange 34, CIPigment Orange 36 , CIPigment Orange 38, CIPigment Orange 40, CIPigment Orange 43, CIPigment Orange 63, and the like.

  In the present embodiment, in addition to the organic pigments listed above, dyes that are insoluble or hardly soluble in water, such as disperse dyes and oil-soluble dyes, can also be suitably used.

  When the above pigment is used as a coloring material for ink jet recording ink, the average particle diameter is preferably 500 nm or less, more preferably 200 nm or less, and further preferably 50 to 100 nm. When the average particle diameter of the core substance is within such a range, the ink for ink jet recording is effective in reliability such as ejection stability and dispersion stability, and can output a high-quality image.

  The ink composition of this embodiment may contain components other than the components listed above. Such components are not particularly limited, but include, for example, conventionally known polymerization accelerators, thermal polymerization inhibitors and dispersants, and other additives.

[Physical properties of photocurable ink composition]
The degree of scratch resistance of the ink composition of the present embodiment is preferably such that several scratches are attached and, more preferably, there are no scratches, from a practical viewpoint. Here, the scratch resistance in this specification is measured and evaluated by the method carried out in the Examples section described later.

  The degree of adhesion of the ink composition of the present embodiment is such that peeling is preferably observed in an area of less than half, more preferably no peeling, from a practical viewpoint. Here, the adhesion in the present specification is measured and evaluated by the method performed in the Examples section described later.

  The degree of storage stability of the ink composition of the present embodiment may be such that a precipitate is observed, but from a practical viewpoint, preferably a slight precipitate is observed, and more preferably no precipitate is present. That is. Here, the storage stability in the present specification is measured and evaluated by the method carried out in the Examples section below.

  The degree of flexibility of the ink composition of the present embodiment may be seen to such an extent that peeling or cracking from the PET film that is the recording medium causes a problem in practice. However, from a practical point of view, peeling or cracking is preferably partially observed, but there is no practical problem. More preferably, there is no problem, that is, peeling and cracking are not observed. Here, the flexibility in the present specification is measured and evaluated by the method performed in the section of Examples described later.

  Thus, according to this embodiment, a photocurable ink composition excellent in scratch resistance and adhesion can be obtained. The ink composition of the present embodiment is excellent in flexibility and storage stability.

[Recording method]
Another embodiment of the invention relates to a recording method. The recording method includes the following printing process and curing process.

[Printing process]
In this step, the photocurable ink composition of the above embodiment is printed on a recording medium with an inkjet recording apparatus.

[Curing process]
In the said process, the said ink composition printed by the said printing process is hardened | cured by irradiation of the light of a specific wavelength (range). The light having a specific wavelength (range) is preferably in the ultraviolet region, more preferably 360 to 400 nm, and even more preferably 380 to 400 nm. When the peak wavelength is within the above range, the curability is further improved. As a light source, for example, a mercury lamp and a metal halide lamp are widely known. On the other hand, there is a strong demand for mercury-free from the viewpoint of environmental protection, and replacement with a GaN-based semiconductor ultraviolet light-emitting device is very useful industrially and environmentally. Furthermore, light emitting diodes (LEDs) and laser diodes (LDs) are small, have a long life, have high efficiency, and are low in cost, and are expected as light sources for photocurable inkjet recording. Among these, a light emitting diode (LED) having a peak wavelength in the range of 360 to 400 nm is preferable.

  As described above, according to the present embodiment, it is possible to provide an ink jet recording method for obtaining a recorded matter having excellent scratch resistance and adhesion.

  Hereinafter, the embodiments of the present invention will be described more specifically with reference to examples and comparative examples. However, the present embodiment is not limited to only these examples.

[Use ingredients]
The components used in the following examples and comparative examples are as follows.
(Monofunctional monomer)
-Phenoxyethyl acrylate biscoat # 192 (manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY LTD., Abbreviated as PEA in Table 1)
Isobornyl acrylate IBXA (Osaka Organic Chemical Co., Ltd., abbreviated as IBXA in Table 1)
Dicyclopentenyloxyethyl acrylate FA-512AS (manufactured by Hitachi Chemical Co., Ltd., abbreviated as DCPOEA in Table 1)
Dicyclopentenyl acrylate FA-511AS (manufactured by Hitachi Chemical Co., Ltd., abbreviated as DCPA in Table 1)
N-vinylcaprolactam (manufactured by BASF, abbreviated as VCL in Table 1)
(Polyfunctional monomer)
Dimethylol tricyclodecane diacrylate EBECRYL IRR214K (manufactured by DAICEL-CYTEC Company LTD., Abbreviated as 2MTCDA in Table 1)
Urethane acrylate (Ebicryl 8402, manufactured by Daicel-Cytec, abbreviated as UA in Table 1)
(Polymerization accelerator)
Aminoacrylate EBECRYL7100 (manufactured by Daicel-Cytec, abbreviated as EBECRYL7100 in Table 1)
(Photopolymerization initiator)
・ IRGACURE 819 (Ciba Japan)
・ DAROCURE TPO (Ciba Japan)
DETX-S (Nippon Kayaku Co., Ltd., abbreviated as DETX in Table 1)
(Slip agent)
Urethane wax (ADS038, manufactured by American Dye Source, Inc., abbreviated as ADS in Table 1)
Oxidized polyethylene wax (AC392, manufactured by Allied Signal Co., abbreviated as AC392 in Table 1)
Paraffin wax (HNP-0190, manufactured by Nippon Seiro Co., Ltd., abbreviated as HNP in Table 1)
(Thermal polymerization inhibitor)
P-methoxyphenol (KANTO CHEMICAL CO., INC., Abbreviated as MP in Table 1)
(Pigment)
IRGALITE BLUE GLVO (Cyan pigment, manufactured by Ciba Japan, abbreviated as BLUE GLVO in Table 1)
(Dispersant)
Solsperse 36000 (manufactured by LUBRIZOL, abbreviated as SOL36000 in Table 1)

[Measurement and evaluation method]
For the photocurable ink compositions obtained in the following Examples and Comparative Examples, or the coating films obtained from the ink compositions, the following scratch resistance, adhesion, storage stability and flexibility were obtained. Evaluation was performed as described above.

[Abrasion resistance]
First, printing is performed on a polyvinyl chloride film using an ink jet recording apparatus in which LEDs that emit 395 nm ultraviolet light are mounted on both ends of an ink jet head filled with a photocurable ink composition, and then ultraviolet light of 395 nm is applied. Irradiation was performed so as to be 500 mJ / cm ² to form a cured film (coating film) having a thickness of 10 μm. And the coating film obtained with the quality paper (Kinishi) was rubbed 100 times with 1 kg load, the surface state of the coating film was observed, and evaluated as follows.
・ AA There was no change,
・ A It remained after the rubbing, but there was no deep scratch.
・ B Scratched at several levels,
・ Scratches above CB level.

[Adhesion]
Using an inkjet recording apparatus equipped with an LED that emits 395 nm ultraviolet light at both ends of an ink jet head filled with a photocurable ink composition, printing is performed on a polyvinyl chloride film, and then 395 nm ultraviolet light is applied at 500 mJ / cm. It was irradiated at ^2, to form a cured film having a thickness of 10 [mu] m. A cellophane tape was adhered to the obtained coating film and then peeled off. The adhesion was evaluated by dividing the presence or absence of the coating film and the degree of peeling into the following ranks A to C.
・ A There was no peeling,
・ B. Peeling was observed in less than half the area.
-C Peeling was observed in more than half the area.

[Storage stability]
First, the viscosity at 25 ° C. of the radiation curable ink composition was measured. This is the initial viscosity.
Next, the viscosity at 25 ° C. of the ink composition was measured after the radiation curable ink composition was allowed to stand (age) at 60 ° C. for one week in an airtight container in an air atmosphere. This is the viscosity after aging. Then, the difference between the initial viscosity (before aging) and the viscosity after aging was calculated. The observation stability was evaluated by dividing this observation result into the following ranks A to C.
A: Within ± 20%
-B: It exceeds ± 20% and is within ± 30%.
-C: exceeds ± 30%.

[Flexibility]
Using an inkjet recording apparatus equipped with an LED that emits 395 nm ultraviolet light at both ends of an ink jet head filled with a photocurable ink composition, printing is performed on a polyvinyl chloride film, and then 395 nm ultraviolet light is applied at 500 mJ / cm. It was irradiated at ^2, to form a cured film having a thickness of 10 [mu] m. The polyvinyl chloride film having the obtained coating film was allowed to stand for 24 hours in a state where it was folded 180 ° so that the printing surface was convex. The softness | flexibility was evaluated by dividing the state of the coating film in that case into the following rank AC.
A There was no problem, that is, no peeling or cracking was seen,
・ B Peeling or cracking was partially observed but there was no practical problem.
-C Peeling or a crack was seen to the extent which becomes a problem practically.

[Examples 1 to 11 and Comparative Examples 1 to 3]
The components shown in Table 1 below were blended so as to have the composition (unit: mass%) shown in Table 1, and this was stirred with a high-speed water-cooled stirrer, whereby a cyan ultraviolet curable ink composition was obtained. Got. The evaluation results are shown in Table 1 below. The blank part in the table means no addition.

  First, comparing the examples and the comparative examples, the ink composition for ink jet recording excellent in scratch resistance, adhesion and flexibility can be obtained because the radiation curable ink composition contains urethane wax. It became clear. Secondly, when Examples 1, 2 and 3 are compared with Examples 5, 6 and 7, respectively, the radiation curable ink composition contains a urethane acrylate in addition to a certain amount of urethane wax. It was found that the balance of the property, adhesion and flexibility was further improved. Third, when Examples 2, 6 and 9 were compared, it was found that as the radiation curable ink composition contained more urethane acrylate, the balance of scratch resistance, adhesion and flexibility was further improved.

Claims (4)

  A radiation curable ink composition comprising a radical polymerizable compound, a photopolymerization initiator, and a urethane wax.   The radiation curable ink composition according to claim 1, comprising 0.5 to 10% by mass of the urethane wax with respect to 100% by mass of the ink composition.   The radiation curable ink composition according to claim 1 or 2, wherein the radical polymerizable compound includes one or more selected from the group consisting of phenoxyethyl acrylate, isobornyl acrylate, and N-vinylcaprolactam. A printing step of printing the radiation curable ink composition according to any one of claims 1 to 3 on a recording medium by an inkjet method;
A curing step of curing the ink composition printed by the printing step by irradiation of a light emitting diode having a peak wavelength in a range of 360 to 400 nm.