WO2019031357A1

WO2019031357A1 - Active energy ray-curable ink composition for inkjet printing

Info

Publication number: WO2019031357A1
Application number: PCT/JP2018/028884
Authority: WO
Inventors: 興範中島; 拓哉明瀬; 良一新田
Original assignee: サカタインクス株式会社
Priority date: 2017-08-08
Filing date: 2018-08-01
Publication date: 2019-02-14
Also published as: JP2019031618A; JP7044496B2

Abstract

The present invention addresses the problem of achieving, as a photocurable ink composition for inkjet printing for image formation or print on a recording medium, an active energy ray-curable ink composition for inkjet printing, which has achieved excellent storage stability, excellent curability by means of ultraviolet light that uses a light emitting diode (LED) as a light source, and excellent gloss of a printed matter formed therewith, while having excellent tack properties and being capable of preventing the occurrence of cracking in print since a print portion exhibits stretchability and followability in cases where a printed paper sheet or film is folded, by having a monomer or oligomer that has an amino group or an amide group additionally blended into a combination of monomers or oligomers, which have specific glass transition temperatures. As a solution for solving the problem, the present invention provides an active energy ray-curable ink composition for inkjet printing, which contains at least a photopolymerizable compound, a photopolymerization initiator and an organic solvent, and which satisfies the following requirements A-G. A. A monofunctional photopolymerizable compound is contained in an amount of 70-95% by mass relative to all photopolymerizable compounds. B. A polyfunctional photopolymerizable compound is contained in an amount of 5-25% by mass relative to all photopolymerizable compounds. C. A monomer and/or oligomer having a glass transition temperature of -30°C or less is contained in an amount of 10-30% by mass relative to all photopolymerizable compounds. D. A monomer and/or oligomer having a glass transition temperature of 80°C or more is contained in an amount of 10% by mass or more relative to all photopolymerizable compounds. E. A monomer and/or oligomer having an amino group and/or an amide group is contained. F. An organic solvent is contained in an amount of 20% by mass or less relative to the total mass of the ink composition. G. The viscosity of the ink composition is 10 mPa·s or less at 25°C.

Description

Active energy ray curable ink composition for ink jet printing

The present invention relates to a photocurable ink composition for inkjet printing and an inkjet printing method. In more detail, the storage stability of the photocurable ink composition for inkjet printing is excellent, and it is curable by active energy rays such as ultraviolet rays using a light emitting diode (LED) as a light source, and printed on a substrate The present invention relates to a photocurable ink composition for inkjet printing, which is excellent in stretchability, cracking of a coating film at the time of bending, glossiness and tackiness.

For example, as described in Patent Documents 1 to 4, for example, the photocurable ink compositions for ink jet printing have been formed by combining monomers having a specific glass transition temperature. However, even if the conventional photocurable ink composition for inkjet printing can adjust the strength of the cured product by adjusting the glass transition temperature, the storage stability of the photocurable ink composition for inkjet printing, the light emitting diode ( The curing property by ultraviolet light using LED as a light source, the stretchability of the printed matter printed on the substrate, cracking of the coating film at bending, glossiness and tackiness were all not satisfactory.

JP, 2016-172841, A JP, 2015-117359, A JP, 2015-083656, A JP, 2013-237834, A

Therefore, the object of the present invention is to add a specific amount of an organic solvent as an ink composition for photocurable inkjet printing for image formation and for printing on a recording medium, and a specific glass transition temperature as a photopolymerizable compound. In addition to the combination of monomers and oligomers possessed by adding monomers or oligomers having an amino group or an amide group, it is excellent in storage stability, and also excellent in curability by ultraviolet light using a light emitting diode (LED) as a light source, and further It is excellent in the glossiness of the formed printed matter, and stretchability, when the printed paper or film is bent, etc., the printed portion can follow and generation of a crack in the printed matter can be prevented, and the activity is excellent in the tackiness. An energy ray-curable ink composition for ink jet printing is obtained.

The inventors of the present invention invented the following active energy ray curable ink composition for ink jet printing as a result of intensive studies to solve the above problems.
1.
An active energy ray curable ink composition for inkjet printing, comprising at least a photopolymerizable compound, a photopolymerization initiator, and an organic solvent,
A. 70 to 95% by mass of monofunctional photopolymerizable compounds in all photopolymerizable compounds,
B. 5 to 25 mass% of multifunctional photopolymerizable compounds in all photopolymerizable compounds,
C. 10 to 30% by mass of monomers and / or oligomers having a glass transition temperature of −30 ° C. or less in all photopolymerizable compounds,
D. 10% by mass or more of monomers and / or oligomers having a glass transition temperature of 80 ° C. or higher in all photopolymerizable compounds,
E. Containing monomers and / or oligomers having an amino group and / or an amido group,
F. 20% by mass or less of an organic solvent based on the total mass of the ink composition
G. The viscosity of the ink composition is 10 mPa · s or less at 25 ° C.
An active energy ray-curable ink composition for inkjet printing satisfying the requirements of A to G of
2.
H. 15 to 45% by mass of monomers and / or oligomers having an amino group and / or an amido group in all photopolymerizable compounds,
I. An acrylated amine compound having two photopolymerizable functional groups and two amino groups in the molecule, and acryloyl morpholine and / or N-vinylcaprolactam,
3. The active energy ray-curable ink composition for ink jet printing according to 1, which further satisfies the requirements of H and I in the above.
3.
1 or 2 as a monomer and / or oligomer having a glass transition temperature of -30 ° C. or less, containing 2 to 10% by mass of a polyfunctional monomer having an ethylene oxide and / or propylene oxide modified backbone in all photopolymerizable compounds An active energy ray curable ink composition for inkjet printing.
4.
Furthermore, the active energy ray-curable ink composition for ink jet printing according to any one of 1 to 3 further comprising a colorant.

According to the active energy ray-curable ink composition for inkjet printing of the present invention, the storage stability is excellent, the curability by ultraviolet light using a light emitting diode (LED) as a light source is also excellent, and the gloss of the formed printed matter is further improved. In addition to being excellent, it has the remarkable effect of being able to follow the printed portion when the stretchability, printed paper, film, etc. is bent, etc. to prevent generation of a crack in the printed, and further to be excellent in tackiness. it can.

It is the schematic which shows the evaluation method of stretchability.

Hereinafter, the photocurable ink composition for inkjet printing (hereinafter also referred to as the ink composition of the present invention) containing at least the photopolymerizable compound, the photopolymerization initiator, and the organic solvent of the present invention will be described in detail. . Among the following categories of compounds of AE, there are compounds included in a plurality of categories. Such compounds are counted in duplicate in their respective contents as belonging to each of the plurality of categories.

<A. Monofunctional photopolymerizable compound>
A. in the present invention As a monofunctional photopolymerizable compound, for example, the following compounds can be adopted.
Butyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, isomyristyl (meth) acrylate, stearyl (meth) acrylate ) Acrylate, isostearyl (meth) acrylate, isobornyl (meth) acrylate, lauryl (meth) acrylate, cyclic trimethylolpropane formal (meth) acrylate, cyclohexyl (meth) acrylate, adamantyl (meth) acrylate, dicyclopentanyl ( N- (meth) acrylates, Acrylates of dicyclopentenyl (meth) acrylate, various (meth) acrylamide monomers such as styrene, acryloyl morpholine, N N-vinylamide monomers such as vinylcaprolactam, benzyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate and ethylene oxide modified product thereof, ethyl carbitol (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-methoxy Ethyl acrylate, polyethylene glycol (meth) acrylate, isoamyl (meth) acrylate, hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyphenoxypropyl (meth) Acrylate, 2-ethylhexyl-diglycol (meth) acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, butoxy Ethyl acrylate, Ethoxydiethylene glycol (meth) acrylate, Ethyl carbitol acrylate, Methoxydiethylene glycol (meth) acrylate, Methoxy polyethylene glycol (meth) acrylate, Methoxy propylene glycol (meth) acrylate, Tetrahydrofurfuryl (meth) acrylate, (2-methyl -2-ethyl-1,3-dioxolan-4-yl) methyl (meth) acrylate, (3-ethyl oxetan-3-yl) methyl methacrylate, phenol ethylene glycol modified acrylate, 2-hydroxypropyl (meth) acrylate, 2 -Hydroxy-3-phenoxypropyl (meth) acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyl oxyethyl phthalic acid, 2 And -acryloyloxyethyl-2-hydroxyethyl-phthalic acid, lactone-modified flexible acrylate, t-butylcyclohexyl (meth) acrylate and the like.
A. The content of the monofunctional photopolymerizable compound is 70 to 95% by mass, preferably 75 to 95% by mass, and more preferably 85 to 90% by mass, in all the photopolymerizable compounds. When the content is less than 70% by mass, the stretchability and the cracking of the coating film at the time of bending tend to decrease, and when the content exceeds 95% by mass, the tackiness and the curability tend to decrease.
In addition, the monofunctional photopolymerizable compound of the glass transition temperature which does not correspond to the monomer or oligomer of following C or D can also be used in the range with which the requirements of following C and D are satisfy | filled.

<B. Multifunctional Photopolymerizable Compound>
B. in the present invention The polyfunctional photopolymerizable compound is a compound having a plurality of carbon-carbon unsaturated bonds in the molecule, and for example, the following compounds can be adopted.
Vinyloxyethoxyethyl (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, dipropylene glycol di (meth) acrylate, (Poly) alkylene glycol di (meth) acrylates such as triethylene glycol di (meth) acrylate and tripropylene glycol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate , Dimethylol-tricyclodecane di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, polytetramethylene glycol diacrylate, tri Tyrolpropane tri (meth) acrylate and its ethylene oxide modified product, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate and its ethylene oxide modified product, dipentaerythritol penta (meth) acrylate and its ethylene oxide modified product And dipentaerythritol hexa (meth) acrylate and ethylene oxide modified products thereof, urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, pentaerythritol ethoxy tetraacrylate, caprolactam modified dipentaerythritol hexaacrylate, etc. be able to.
B. The content of the polyfunctional photopolymerizable compound is 5 to 25% by mass, preferably 5 to 20% by mass, more preferably 10 to 15% by mass, in all the photopolymerizable compounds. When the content is less than 5% by mass, the curability and tackiness tend to decrease, while when the content is more than 25% by mass, the stretchability and cracking of the coating film at the time of bending tend to decrease.
In addition, in the range which satisfy | fills the requirements of following C and D, the polyfunctional photopolymerizable compound of the glass transition temperature which does not correspond to the monomer or oligomer of following C or D can also be used.

<C. Monomer and / or oligomer having a glass transition temperature of -30 ° C. or less>
Monomers having a glass transition temperature of −30 ° C. or less include ethylene oxide-modified trimethylolpropane triacrylate, polyfunctional oxides having ethylene oxide and / or propylene oxide-modified backbone such as alkoxylated tetrahydrofurfuryl acrylate, isooctyl acrylate, and triol. Decyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, 2-ethylhexyl carbitol acrylate, ethyl carbitol acrylate, 2-methoxyethyl acrylate, 2-methoxybutyl acrylate, 4-hydroxybutyl acrylate, diethylene glycol monoethyl Ether acrylate, ethoxydiethylene glycol acrylate, isoamyl Acrylate, isodecyl acrylate, isooctyl acrylate, tetradecyl acrylate, caprolactone acrylate, methoxy tripropylene glycol acrylate, and EO (ethylene oxide) modified succinic acid acrylate.
The oligomer having a glass transition temperature of -30.degree. C. or less may have only one or more monomers having a glass transition temperature of -30.degree. C. or less as a copolymer component, or the monomer type 1 having a glass transition temperature of -30.degree. It is an oligomer which copolymerizes one or more kinds of monomers having a glass transition temperature exceeding 30 ° C. as described above, and as a result, the glass transition temperature becomes −30 ° C. or less.
C. The content of monomers and / or oligomers having a glass transition temperature of −30 ° C. or less is 10 to 30% by mass, preferably 10 to 25% by mass, and more preferably 15 to 20% by mass in all photopolymerizable compounds. %. If the content is less than 10% by mass, the bendability of the coating film is reduced, while if it exceeds 30% by mass, the tackiness tends to be reduced.
Among these, from the viewpoint of compatibility with the oligomer component, it is preferable to incorporate 2 to 10% by mass of a polyfunctional monomer or oligomer component having an ethylene oxide and / or propylene oxide modified skeleton in all photopolymerizable compounds.

<D. Monomer and / or oligomer having a glass transition temperature of 80 ° C. or higher>
As monomers having a glass transition temperature of 80 ° C. or higher, acryloyl morpholine, vinylcaprolactam, acrylonitrile, acrylamide, styrene, methyl methacrylate, (meth) acrylic acid, isobornyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, Ethoxylated bisphenol A diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate.
The oligomer having a glass transition temperature of 80 ° C. or more has one or more of the above monomers having a glass transition temperature of 80 ° C. or more as a copolymer component, or the above glass transition temperature of one or more monomers having a glass transition temperature of 80 ° C. or more It is an oligomer having a transition temperature of 80 ° C. or higher as a result of copolymerizing one or more monomers having a transition temperature of less than 80 ° C.
D. The content of monomers and / or oligomers having a glass transition temperature of 80 ° C. or more is 10% by mass or more, preferably 50% by mass or less, and more preferably 15% by mass or more and 50% by mass or less in all photopolymerizable compounds. % Or less. If the content is less than 10% by mass, the tackiness tends to decrease.

E. Monomer and / or Oligomer Having Amino Group and / or Amide Group>
Monomers having an amino group and / or an amide group are various (meth) acrylamide monomers such as acrylamide and acryloyl morpholine, N-vinylamide monomers such as N-vinylcaprolactam, and two photopolymerizable functional groups in the molecule and It is an acrylated amine compound such as CN 371 (manufactured by Sartomer), which is an oligomer of an acrylated amine compound having two amino groups.
E. The content of the monomer and / or oligomer having an amino group and / or an amido group can be arbitrarily determined. However, the total amount of the photopolymerizable compound is preferably 15% by mass or more, more preferably 15% by mass to 45% by mass, and still more preferably 25% by mass to 45% by mass. If the content is less than 15% by mass, curability and tackiness may be reduced.

<F. Organic solvent>
It is selected from glycol ethers such as dipropylene glycol dimethyl ether and diethylene glycol ethyl methyl ether, glycol ether esters, alcohols, ketones, organic carbonates and mixtures thereof.
F. The content of the organic solvent is preferably 20% by mass or less, more preferably 3.0 to 15% by mass, and more preferably 5.0 to 10% by mass, based on the total mass of the ink composition. If the content exceeds 20% by mass, problems may occur in terms of viscosity, dischargeability, and ink film physical properties.

<Photoinitiator>
2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide (trade name: TPO, manufactured by Lambson), bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (trade name: IRGACURE 819, manufactured by BASF Corp.) ).
The content of the photopolymerization initiator is preferably in the range of 3 to 25% by mass, and more preferably in the range of 5 to 15% by mass, based on the total mass of the photopolymerizable components.
Within this range, it is important to maintain the dischargeability, curability and storage stability of the ink composition in a well-balanced manner.

<Sensitizer>
The photocurable ink composition for ink jet printing of the present invention further has a light absorbing property mainly in the wavelength range of 400 nm or more of ultraviolet light in order to promote the curability to ultraviolet light from a light emitting diode (LED) as a light source. The photosensitizer (compound) which has a sensitizing function of hardening reaction by the light of the wavelength of the range can be used together with a photoinitiator.
As such a sensitizer, an anthracene sensitizer, a thioxanthone sensitizer and the like are preferable, and a thioxanthone sensitizer is preferable. These can be used alone or in combination of two or more.
Specifically, anthracene sensitizers such as 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-bis (2-ethylhexyloxy) anthracene, 2 Thioxanthone-based sensitizers such as 2,4-diethylthioxanthone, 2-isopropyl thioxanthone, 4-isopropyl thioxanthone and the like can be mentioned. Representative examples of commercially available products include DBA and DEA (manufactured by Kawasaki Kasei Kogyo Co., Ltd.) as anthracene sensitizers, and DETX and ITX (manufactured by Lambson) as thioxanthone sensitizers.
The content of the sensitizer is preferably in the range of 0 to 8% by mass based on the total mass of the photopolymerizable component. Even if it exceeds 8 mass%, the improvement of the effect is not seen and it is not preferable because it is excessive.
When a thioxanthone-based sensitizer is used as a sensitizer, the photocurable ink composition for ink jet printing tends to turn yellow, so it has a yellowish color than the color based on the pigment (the original hue). Since the color is obtained, it is preferable to appropriately determine the content of the thioxanthone sensitizer for each color.
Specifically, in the white ink composition and the clear ink composition which are susceptible to the change in color tone, it is preferable not to contain the thioxanthone compound as a sensitizer. Further, in the case of the magenta ink composition and the cyan ink composition, it is preferable to use in the range where the problem of the hue does not occur because the change of the hue becomes a problem. In addition, since the black ink composition and the yellow ink composition do not affect the hue even if there is a color change and the photopolymerizability is poorer than other hues, the thioxanthone compound is used in combination as a sensitizer. Is preferred.

<G. The viscosity of the ink composition is 10 mPa · s or less at 25 ° C.>
The viscosity of the ink composition of the present invention is required to be 10 mPa · s or less at 25 ° C. When it exceeds 10 mPa · s, it may be difficult to eject the ink composition from the nozzle for ink jet printing.
The value of viscosity in the present invention is a viscosity measured under conditions of 25 ° C. and 20 rpm using an E-type viscometer (trade name: RE100L viscometer, manufactured by Toki Sangyo Co., Ltd.).

<Colorant>
The photocurable ink composition for ink jet printing of the present invention can also be made to contain a colorant of each color to obtain a photocurable ink composition for ink jet printing of each color.
As such a colorant, pigments and dyes conventionally used in conventional photocurable ink compositions for ink jet printing can be used without particular limitation, but in view of light resistance, organic pigments or inorganic pigments, etc. Pigments are preferred.
And as organic pigments, for example, dye lake pigments, azo type, benzimidazolone type, phthalocyanine type, quinacridone type, anthraquinone type, dioxazine type, indigo type, thioindico type, perylene type, perinone type, diketopyrrolopyrrole type, Examples of pigments include isoindolinone type, nitro type, nitroso type, anthraquinone type, flavanthrone type, quinophthalone type, pyranthrone type, and indanthrone type. Examples of inorganic pigments include carbon black, titanium oxide, bengala, graphite, iron black, chromium oxide green, aluminum hydroxide and the like.
Moreover, the following are mentioned as a specific example of the pigment for every typical hue of the photocurable ink composition for inkjet printing of this invention.
First, as a yellow pigment for use as a photocurable yellow ink composition for inkjet printing, for example, C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 42, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 108, 109, 114, 120, 128, 129, 138, 139, 150, 151, 155, 166, 180, 184, 185, 213 and the like, preferably C.I. I. Pigment Yellow 150, 155, 180, 213, and the like.
As a magenta pigment for use as a magenta ink composition for photocurable inkjet printing, for example, C.I. I. Pigment Red 5, 7, 12, 22, 38, 48: 1, 48: 2, 48: 4, 49: 1, 53: 1, 57: 57: 1, 63: 1, 101, 102, 112, 122, 123, 144, 146, 149, 168, 177, 178, 179, 180, 184, 185, 190, 202, 209, 224, 242, 254, 255, 270, C.I. I. Pigment Violet 19 etc., preferably C.I. I. Pigment Red 122, 202, C.I. I. Pigment Violet 19 and the like.
As a cyan pigment for use as a cyan ink composition for photocurable inkjet printing, for example, C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 18, 22, 27, 29, 60, etc., preferably C . I. Pigment Blue 15: 4 and the like.
As a black pigment for using as a black ink composition for photocurable inkjet printing, carbon black (CI.Pigment Black 7) etc. are mentioned, for example.
Examples of white pigments for use as a white ink composition for photo-curable inkjet printing include titanium oxide, aluminum oxide and the like, and preferably titanium oxide surface-treated with various materials such as alumina and silica. Can be mentioned.
The content of the pigment in the photocurable inkjet printing ink composition of the present invention is preferably 1 to 20% by mass with respect to the total amount of the photocurable inkjet printing ink composition. When the content of the pigment is less than 1% by mass, the image quality of the obtained printed matter tends to be deteriorated. On the other hand, if it exceeds 20% by mass, the viscosity characteristics of the photocurable ink composition for ink jet printing tend to be adversely affected.

<Pigment dispersant>
In addition, the photocurable ink composition for inkjet printing of the present invention may contain a pigment dispersant, if necessary.
The pigment dispersant is used to improve the dispersibility of the pigment and the storage stability of the ink composition of the present invention, and those conventionally used can be used without particular limitation, and among them, polymer dispersion It is preferred to use an agent. As such pigment dispersants, carbodiimide type dispersants, polyester amine type dispersants, fatty acid amine type dispersants, modified polyacrylate type dispersants, modified polyurethane type dispersants, multi-chain type polymer nonionic dispersants, Polymeric ion active agents and the like can be mentioned. These pigment dispersants can be used alone or in combination of two or more.
The above pigment dispersant is preferably contained in an amount of 1 to 200 parts by mass, based on 100 parts by mass of the total pigment to be used. When the content of the pigment dispersant is less than 1 part by mass, the pigment dispersibility and the storage stability of the ink composition of the present invention may be reduced. On the other hand, it may be contained in excess of 200 parts by mass, but there may be no difference in the effect. The more preferable lower limit of the content of the pigment dispersant is 5 parts by mass, and the more preferable upper limit is 60 parts by mass.

<Surfactant>
The photocurable ink composition for inkjet printing according to the present invention has an interface such as a silicon-based surfactant which has conventionally been used as a surfactant in photocurable ink compositions for inkjet printing according to the inkjet head used. It is preferable to include an activator in order to improve the ejection stability.
Specific examples of silicone surfactants include polyether-modified silicone oil, polyester-modified polydimethylsiloxane, polyester-modified methylalkylpolysiloxane and the like. These can be used alone or in combination of two or more.
The content of the surfactant in the ink composition of the present invention is preferably 0.005 to 1.0% by mass. If it is less than 0.005% by mass, the surface tension of the photocurable inkjet printing ink composition of the present invention becomes high, and the ejection stability from the inkjet head is reduced. On the other hand, when it exceeds 1.0% by mass, bubbles increase in the photocurable ink composition for inkjet printing, and the ejection stability is lowered.

<Additives>
Various additives can be added to the photocurable ink composition for ink jet printing of the present invention in order to develop various functionalities as needed. Specifically, a light stabilizer, a surface treatment agent, an antioxidant, an antiaging agent, a crosslinking accelerator, a polymerization inhibitor, a plasticizer, an antiseptic, a pH adjuster, an antifoamer, a moisturizer and the like can be mentioned. . In addition, a non-curable resin that functions as a vehicle may or may not be blended.

The photocurable ink composition for inkjet printing of the present invention obtained from the above materials has a flash point of 70 ° C. or higher measured using a Seta sealed flash point measuring apparatus according to the method according to JIS K2265. Is preferred. By having such a flash point, the ink composition of the present invention can be made to have a level corresponding to the flammable liquid class 4 in GHS, and is excellent in safety such as low flammability.
The photocurable ink composition for inkjet printing of the present invention is required to have a viscosity at 25 ° C. of 10 mPa · s or less. More specifically, the specific viscosity of the photocurable inkjet printing ink composition can also be designed to be applicable to each inkjet device.
In addition, in this specification, a viscosity is a viscosity measured on conditions of 25 degreeC and 20 rpm using E-type viscosity meter (brand name: RE100L-type viscosity meter, Toki Sangyo Co., Ltd. make).
The photocurable ink composition for ink jet printing according to the present invention contains a specific amount of the above-mentioned specific photopolymerizable component and an acyl phosphine oxide type photopolymerization initiator to thereby emit ultraviolet light, particularly a light emitting diode (LED) as a light source. It has excellent curability to ultraviolet light, good adhesion and abrasion resistance to base materials such as flooring, vinyl chloride, polycarbonate etc., excellent discharge stability and storage stability, high flash point, low skin irritation and It can be excellent in all the safety such as low odor.

The method for preparing the ink composition of the present invention is not particularly limited, and all of the above-described materials can be added and mixed by using a bead mill, a 3-roll mill or the like.
The conc-based ink is obtained in advance by mixing the pigment, the pigment dispersant and the photopolymerizable component, and the conc-based ink has a composition of a desired photocurable ink jet printing ink composition. It can also be prepared by adding additives such as a photopolymerizable component, a photopolymerization initiator, and a surfactant if necessary.
As a substrate on which the ink composition of the present invention is to be printed, floor materials, vinyl chloride, polyethylene terephthalate, polycarbonate and the like are preferable, but conventionally, a substrate on which a photocurable ink composition for inkjet printing is printed (paper, plastic Films, capsules, gels, metal foils, glass, cloth, etc.) can be printed without problems.

Specifically, as a method of printing and curing the ink composition of the present invention, a coating film of the ink composition of the present invention landed on the substrate after discharging the ink composition of the present invention to the substrate by an inkjet head And the method of exposing and curing with light.
For example, for ejection (printing of an image) on a substrate, the ink composition of the present invention is supplied to a low viscosity compatible printer head of a printer for inkjet recording, and the film thickness of the coating film on the substrate is, for example, It can be carried out by discharging the ink composition from a printer head so as to be 1 to 60 μm. Further, exposure to light and curing (curing of the image) can be carried out by irradiating light to the coating film of the ink composition of the present invention applied to the substrate as an image.
As a printer for an ink jet recording system for printing the ink composition of the present invention, a printer for an ink jet recording system conventionally used can be used. In addition, when using the printer device for a continuous type inkjet recording method, a conductivity imparting agent is further added to the ink composition of the present invention to adjust the conductivity.
As a light source for curing the coating film, ultraviolet light (UV), ultraviolet light (light emitting diode (LED)), electron beam, visible light and the like can be mentioned. From the environmental point of view, the light emission peak wavelength is preferably in the range of 350 to 420 nm. Light emitting diode (LED) that generates ultraviolet light.
The ultraviolet light using a light emitting diode (LED) as a light source is "light emitted from the light emitting diode that generates ultraviolet light having an emission peak wavelength in the range of 350 to 420 nm".

(Example)
Preparation of Photocurable Ink Composition for Ink Jet Printing The present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. In addition, unless there is particular notice, "%" means "mass%" and "part" means "mass part".
<Glass transition temperature Tg>
Here, the glass transition temperature Tg is a theoretical glass transition temperature determined by the following Wood's equation.
Wood's formula: 1 / Tg = W ₁ / Tg ₁ + W ₂ / Tg ₂ + W ₃ / Tg ₃ + ················ Wx / Tgx
(Wherein, Tg ₁ to Tgx are glass transition temperatures of homopolymers of the polymerizable monomers 1, 2, 3... X constituting the copolymer, W ₁ to Wx are monomers 1, The mass fraction of each of 2, 3 ... x, Tg represents a theoretical glass transition temperature, provided that the glass transition temperature in the Wood's equation is an absolute temperature).
The materials used in the following examples and comparative examples are as follows.

<Amine Modified Oligomer>
CN 371 (made by Sartmar)
<Photopolymerizable compound>
Acryloyl morpholine vinylcaprolactam butylcyclohexanol acrylate (4-tert-butylcyclohexanol acrylate)
Isobornyl acrylate benzyl acrylate EO (3) modified trimethylolpropane triacrylate (ethoxylated (3) trimethylolpropane triacrylate (made by Sartomer))
Ethyl carbitol acrylate <ketone resin>
SK / benzyl acrylate varnish (40/60): SK resin (a mixture of 40 parts by mass and 60 parts by mass of benzyl acrylate varnish)
<Solvent>
Propylene glycol dimethyl ether diethylene glycol ethyl methyl ether

<Photoinitiator>
TPO: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (manufactured by LAMBERTI)
SB-PI 719: bis (2,4,6-trimethyl benzoyl) -diphenyl phosphine oxide (sorted by company)
<Photosensitizer>
DETX: 2,4-diethylthioxanthone (Lambson)
<Polymerization inhibitor>
UV-5 = dioctyl maleate (manufactured by Chromachem)
UV-22 = quinones polymerization inhibitor (manufactured by Chromachem)
<Silicon based leveling agent>
BYK-315N (made by BIC Chemie)
BYK-331 (made by BIC Chemie)
<Pigment dispersant>
Solsparse 32000 (made by Nippon Lubrizol Corporation)

<Base composition>
Eiger mill (using zirconia beads with a diameter of 0.5 mm as media) using a mixture of pigment, pigment dispersant and photopolymerizable component in a blending ratio (mass ratio) of 16/6/78 The mixture was dispersed to obtain a base composition.

Each component is mix | blended so that it may become the combination composition (mass%) of Table 1 and Table 2 with the obtained base composition, it stirs and mixes, and the ink of the photocurable inkjet printing ink of an Example and a comparative example The composition was obtained.

(Measurement of viscosity of ink composition)
About each ink composition for photocurable inkjet printing obtained by the Example and the comparative example, using E type viscometer (brand name: RE100L type viscometer, Toki Sangyo Co., Ltd. make), temperature 25 ° C, a rotor The viscosity was measured at a rotational speed of 20 rpm. The results are shown in Tables 1 and 2.
(Storage stability)
The ink compositions obtained in Examples 1 to 14 and Comparative Examples 1 to 7 were separately introduced into glass bottles, sealed, and stored for 7 days at 70 ° C., and the state was evaluated according to the following evaluation criteria.
○: Thickened, sediment is not observed at all. Δ: Thickened or sediment returned to some degree when lightly shaken. ×: Thickening or sediment, not returned to the original even when strongly shaken. (Curable)
With a UV-LED light lamp manufactured by Foseon Technology, under the irradiation condition (UV accumulated light amount per second 60 mJ / cm ² ), the distance between the lamp and the coated surface of the ink is 2 cm, and the irradiation time per time is 1 second. The number of times of irradiation until the tackiness of the surface was lost was evaluated.
(Tackiness)
The tackiness was evaluated by pointing each cured coating film (substrate = polycarbonate plate) and visually confirming the state of the surface of the coating film.
○: no fingerprints on the coating film Δ: fingerprints slightly on the coating film ×: fingerprints on the coating film (flexibility)
Coatings of the ink compositions obtained in Examples 1 to 14 and Comparative Examples 1 to 7 are formed using an inkjet recording apparatus equipped with an inkjet nozzle for low viscosity ink, and the ridge side and the valley side are each 180 degrees And the foldability after printing was evaluated according to the following evaluation criteria.
:: No creases or fine cracks occur in the coating film when bent 細: A fine crack occurs when bent B: Cracks in the line when bent (stretchability)
Using an inkjet recording device equipped with an inkjet nozzle for low viscosity ink, cut it into a film of 2 cm × 10 cm in size formed on a polyvinyl chloride film for stretching, prepare a test piece, and measure the test piece with a tensile tester The film was stretched at a tensile speed of 50 mm / min under an environment of 25 ° C., and after storage for 1 week at 25 ° C., the cured film was measured for a stretching ratio by a length that can be stretched without cracking. .
Here, as shown in FIG. 1, when the distance between the black point and the black point in the central portion described so as to sandwich the center of the measurement sample piece becomes X cm from 1 cm before stretching, the stretching ratio is { It is assumed that (X-1) / 1} × 100 [%].
It evaluated according to the following evaluation criteria.
○: 100% or more Δ: 50% or more, less than 100% ×: less than 50% (gloss)
Coating films of the ink compositions obtained in Examples 1 to 14 and Comparative Examples 1 to 7 were formed using an inkjet recording apparatus equipped with an inkjet nozzle for low viscosity ink, and visually observed according to the following evaluation criteria evaluated.
○: The film has a sense of glossiness 塗膜: The film has a slight roughness, and the surface looks a little blurry white ×: The film has a roughness, the surface looks blurry

According to the above examples, an ink jet ink composition having an appropriate viscosity and excellent storage stability and curability can be obtained, and an ink jet excellent in tackiness, bendability, stretchability, and gloss. The coating film by the ink composition was able to be obtained.
However, B.I. According to Comparative Example 1 which does not contain a polyfunctional photopolymerizable compound, the result is low in viscosity and inferior in tackiness. According to Comparative Example 2 in which the polyfunctional photopolymerizable compound is contained in excess, the result was poor in stretchability.
C. According to Comparative Example 3 which does not contain a monomer and / or oligomer having a glass transition temperature of -30 ° C. or less, the result is inferior in bendability. According to Comparative Example 4 in which the glass transition temperature contains a monomer and / or oligomer in excess of −30 ° C. or less, the result was inferior in tackiness.
D. According to the comparative example 5 which does not contain a monomer and / or an oligomer whose glass transition temperature is 80 degreeC or more, it resulted in it being inferior to tackiness.
F. According to the comparative example 6 which does not contain an organic solvent, it was inferior to glossiness and conversely according to the comparative example 7 contained exceeding 20 mass%, it was inferior to tackiness.

Claims

An active energy ray curable ink composition for inkjet printing, comprising at least a photopolymerizable compound, a photopolymerization initiator, and an organic solvent,
A. 70 to 95% by mass of monofunctional photopolymerizable compounds in all photopolymerizable compounds,
B. 5 to 25 mass% of multifunctional photopolymerizable compounds in all photopolymerizable compounds,
C. 10 to 30% by mass of monomers and / or oligomers having a glass transition temperature of −30 ° C. or less in all photopolymerizable compounds,
D. 10% by mass or more of monomers and / or oligomers having a glass transition temperature of 80 ° C. or higher in all photopolymerizable compounds,
E. Containing monomers and / or oligomers having an amino group and / or an amido group,
F. 20% by mass or less of an organic solvent based on the total mass of the ink composition
G. The viscosity of the ink composition is 10 mPa · s or less at 25 ° C.
An active energy ray-curable ink composition for inkjet printing satisfying the requirements of A to G of
H. 15 to 45% by mass of monomers and / or oligomers having an amino group and / or an amido group in all photopolymerizable compounds,
I. An acrylated amine compound having two photopolymerizable functional groups and two amino groups in the molecule, and acryloyl morpholine and / or N-vinylcaprolactam,
The active energy ray-curable ink composition for ink jet printing according to claim 1, which further satisfies the requirements for H and I in the above.
The composition according to claim 1 or 2, wherein 2 to 10% by mass of a polyfunctional monomer having an ethylene oxide and / or propylene oxide modified skeleton is contained as a monomer and / or oligomer having a glass transition temperature of -30 ° C or less in all photopolymerizable compounds. The active-energy-ray-curable ink composition for inkjet printing as described.
The active energy ray curable ink composition for ink jet printing according to any one of claims 1 to 3, further comprising a colorant.