JP2004131725A - Ultraviolet ray curable ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet ray curable ink excellent in flexibility, scratch resistance and adhesion and which provide a cured film not breaking even recorded on a flexible material. <P>SOLUTION: The ultraviolet ray curable ink comprises a coloring component, a reactive oligomer and/or a reactive prepolymer, a reactive diluent and a photoinitiator, wherein both the glass transition temperatures of the polymer of the reactive oligomer and/or reactive prepolymer unit and the reactive diluent lay at -25 to 70°C, respectively. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an ultraviolet curable ink capable of recording an image on a flexible (flexible) base material.

Conventionally, many printing methods using ultraviolet curable ink have been known.

UV-curable inks have high hardness of the cured film, strong adhesion to the substrate, and excellent fastness such as scratch resistance, weather resistance, and peel resistance. In recent years, it has attracted attention because it can be used and organic solvents and the like are unnecessary.

However, on the other hand, the cured film of the UV-curable ink is very hard, so when an image is recorded on a flexible (flexible) substrate (film, metal foil, etc.), it follows the cured film. There is a disadvantage that the film is broken when the film is bent.

紫外線 Further, ultraviolet curing of a composition containing a (meth) acrylate having a (meth) acryloyl group as a reactive prepolymer or a reactive diluent has been performed (for example, see Patent Document 1). When a low-viscosity fast-curable (meth) acrylate composition disclosed in Patent Document 1 is used as an ultraviolet-curable ink for a flexible substrate (film, metal foil, etc.), the flexible substrate is used. When the cured film is bent, the cured film is cracked and peeled off from the substrate.

As described above, even when the recording is performed on a flexible substrate, the cured film is not broken and has excellent follow-up properties, scratch resistance, and UV curing ink excellent in adhesion. Did not exist.

JP-A-7-330835

It is an object of the present invention to provide an ultraviolet curable ink which has excellent followability without breaking a cured film even when recording is performed on a flexible substrate, and also has excellent scratch resistance and adhesiveness. Is to provide.

As a result of intensive studies on the background of the problem, the present invention has found that the reactive oligomer and / or the reactive prepolymer used alone in the ultraviolet curable ink have a glass transition point of a polymer and a reactive dilution. Paying attention to the glass transition point of the polymer in the agent alone, by using a polymer having a glass transition point within a specific range, the following property, scratch resistance, ultraviolet curing type excellent in adhesiveness This makes it possible to obtain ink.

The present invention relates to an ultraviolet curable ink comprising a coloring component, a reactive oligomer and / or a reactive prepolymer, a reactive diluent, and a photopolymerization initiator, wherein the reactive oligomer and / or the reactive prepolymer alone , And the glass transition point of the polymer of the reactive diluent alone is -25 to 70 ° C.

差 The difference between the glass transition point of the polymer of the reactive oligomer and / or the reactive prepolymer alone and the glass transition point of the polymer of the reactive diluent alone is preferably within 30 ° C.

Advantageous Effects of Invention According to the present invention, an ultraviolet curable ink having excellent followability without breaking a cured film even when recording is performed on a flexible substrate, and having excellent scratch resistance and adhesiveness can be obtained. Can be

The present invention will be described in more detail.

紫外線 The ultraviolet curable ink of the present invention is an ultraviolet curable ink comprising a coloring component, a reactive oligomer and / or a reactive prepolymer, a reactive diluent, and a photopolymerization initiator.

The glass transition point (Tg) of the polymer of the reactive oligomer and / or the reactive prepolymer alone, and the Tg of the polymer of the reactive diluent alone are −25 to 70 ° C., preferably 0 to 70 ° C., respectively. Preferably it is 5-50 degreeC, More preferably, it is 10-30 degreeC.

Here, Tg refers to a temperature at which a polymer starts to have fluidity from a hard glassy state to a rubbery state when heated. Tg is greatly affected by the binding interaction, molecular weight, number of functional groups, chemical skeleton, etc. of the polymer. Generally, when the temperature is lower than Tg, the polymer becomes hard and brittle. When the temperature is higher than Tg, the polymer has a certain strength and flexibility because the molecules have fluidity.

ガ ラ ス The glass transition point (Tg) of the present invention is a Tg of a homopolymer, ie, a polymer of a reactive oligomer and / or a reactive prepolymer alone and a polymer of a reactive diluent alone. It can be measured with a differential scanning calorimeter.

The Tg of the polymer in the reactive oligomer and / or reactive prepolymer alone, and the Tg of the polymer in the reactive diluent alone are −25 to 70 ° C., preferably 0 to 70 ° C., more preferably 5 to 70 ° C. By using the UV-curable ink at 50 ° C., more preferably 10 to 30 ° C., the cured film obtained by UV irradiation has scratch resistance, adhesiveness, flexibility, and conformability to a flexible substrate. Excellent. If the Tg is higher than 70 ° C., the cured film of the ultraviolet curable ink becomes too hard, so that it has no flexibility and becomes brittle. On the other hand, when Tg is lower than −25 ° C., the solidity such as scratch resistance is deteriorated, and tackiness is caused.

Examples of the reactive oligomer and / or reactive prepolymer include urethane acrylate, polyester acrylate, epoxy acrylate, silicone acrylate, and polybutadiene acrylate, and may be used alone or in combination. Among these reactive oligomers and / or reactive prepolymers, urethane acrylate is preferably used because of its excellent adhesion to various materials and its excellent toughness, flexibility, chemical resistance and low-temperature properties. Selected.

Reactive oligomers and / or reactive prepolymers have a Tg of a polymer alone of −25 to 70 ° C., preferably 0 to 70 ° C., more preferably 5 to 50 ° C., and still more preferably 10 to 30 ° C. Whatever is required. If the Tg of the polymer alone is higher than 70 ° C., the cured film of the ultraviolet-curable ink becomes too hard, so that it has no flexibility and becomes brittle. If the temperature is lower than −25 ° C., the rigidity such as scratch resistance is deteriorated, and tackiness is caused.

In the present invention, a reactive oligomer and / or a reactive prepolymer having a Tg of a polymer alone of −25 to 70 ° C. is an essential component. If necessary, a Tg of a polymer alone is −25. Those outside the range of -70 ° C may be used. In this case, the reactive oligomer and / or reactive prepolymer having a Tg outside the range of −25 to 70 ° C. is not more than 20% of the reactive oligomer and / or reactive prepolymer having a Tg of −25 to 70 ° C. It is preferable that

The reactive oligomer and / or reactive prepolymer used in the present invention preferably has a viscosity at 60 ° C of 40 to 10,000 cps, particularly preferably 40 to 7000 cps. If the viscosity at 60 ° C. of the reactive oligomer and / or the reactive prepolymer is less than 40 cps, it is expected that the reactive oligomer or the reactive prepolymer does not have a sufficient molecular weight. Scratch resistance and adhesiveness tend to be insufficient, and if it exceeds 10,000 cps, the amount that can be added to the ink is very slightly limited, and the components of the ink are mostly occupied by the reactive diluent. The resulting cured film tends to have insufficient scratch resistance and adhesiveness.

The functional group in the molecule of the reactive oligomer and / or reactive prepolymer used is preferably bifunctional. The reason is that, when the functional group of the ink constituent material is large, the number of crosslinking points of the cured film is increased and the cured film obtained is hard, but on the other hand, it becomes brittle and easily becomes a cured film having poor adhesiveness and scratch resistance. Because.

、 If the number of functional groups in the molecule is not 2 or more, it is preferable to be bifunctional in consideration that the molecule does not form a continuous film at the time of curing.

The reactive diluent has a Tg of the polymer of the reactive diluent alone of −25 to 70 ° C., preferably 0 to 70 ° C., more preferably 5 to 50 ° C., and still more preferably 10 to 30 ° C. Any reactive diluent may be used. When the temperature is in the range of −25 to 70 ° C., printing becomes possible, and the cured film obtained by irradiation with ultraviolet rays has excellent scratch resistance, adhesiveness, flexibility, and excellent followability with a flexible substrate.

In the present invention, a reactive diluent having a Tg of a polymer alone of −25 to 70 ° C. is an essential component, but if necessary, a Tg of a polymer alone outside a range of −25 to 70 ° C. May be used in combination. In this case, the reactive diluent having a Tg outside the range of −25 to 70 ° C. is preferably 20% or less of the reactive diluent having a Tg of −25 to 70 ° C.

Examples of the reactive diluent include hexafunctional dipentaerythritol hexaacrylate and modified products thereof, pentafunctional dipentaerythritol hydroxypentaacrylate, tetrafunctional pentaditrimethylolpropane tetraacrylate, and ethoxylated pentaerythritol tetraacrylate. Pentaerythritol tetraacrylate, trifunctional trimethylolpropane triacrylate, ethylene oxide-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, tris (2-hydroxyethyl) isocyanurate triacrylate, propoxylated glyceryl triacrylate, bifunctional Neopentyl glycol diacrylate hydroxypivalate, polytetramethylene glycol diact Rate, trimethylolpropane acrylate benzoate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol (200) diacrylate, polyethylene glycol (400) diacrylate, polyethylene glycol (600) diacrylate , Polyethylene glycol (1000) diacrylate, polypropylene glycol (400) diacrylate, polypropylene glycol (700) diacrylate, neopentyl glycol diacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 6,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, dimethyl -Tricyclodecane diacrylate, bisphenol A ethylene oxide adduct diacrylate, and monofunctional caprolactone acrylate, tridecyl acrylate, isodecyl acrylate, isooctyl acrylate, isomiristyl acrylate, isostearyl acrylate, 2-ethylhexyl- Diglycol diacrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, neopentylfuricol acrylate benzoate, isoamyl acrylate, lauryl acrylate, stearyl acrylate, butoxyethyl acrylate, ethoxy-diethylene glycol acrylate, Methoxy-triethylene glycol acrylate, methoxy-polyethylene glycol Acrylate, methoxydipropylene glycol acrylate, phenoxyethyl acrylate, phenoxy-polyethylene glycol acrylate, nonylphenol ethylene oxide adduct acrylate, tetrahydrofurfuryl acrylate, isobonyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy -3-phenoxypropyl acrylate, 2-acryloyloxyethyl-succinic acid, 2-acryloyloxyethyl-phthalic acid, 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid. Further, a reactive diluent in which a functional group of phosphorus or fluorine is imparted to these may be used. These reactive diluents can be used alone or in combination.

官能 The functional group in the molecule of the reactive diluent used is preferably bifunctional. The reason is that, when the functional group of the ink constituent material is large, the number of crosslinking points of the cured film is increased and the cured film obtained is hard, but on the other hand, it becomes brittle and easily becomes a cured film having poor adhesiveness and scratch resistance. Because.

In addition, it is desired that the number of functional groups is small because of the reasons described above and the dilutability of the ink. However, unless the number of functional groups in the molecule is 2 or more, the molecule does not form a continuous film during curing. In view of this, it is preferable that the compound is bifunctional.

Among these bifunctional reactive diluents, tetraethylene glycol diacrylate, polyethylene glycol (400) diacrylate, and polyethylene glycol (600) have a relatively low viscosity when an ink jet method is used as a recording method. ) Diacrylate, polypropylene glycol (400) diacrylate, polypropylene glycol (700) diacrylate are more preferred.

差 The difference between the Tg of the polymer of the reactive oligomer and / or the reactive prepolymer alone and the Tg of the polymer of the reactive diluent alone is preferably within 30 ° C. More preferably, it is within 20 ° C. If the temperature exceeds 30 ° C., the characteristics of either the reactive oligomer and / or the reactive prepolymer and the reactive diluent will be remarkably exhibited. Therefore, for example, the cured film tends to be too hard or the cured film tends to have tackiness.

(4) Examples of the photopolymerization initiator include benzoin-based, thioxanthone-based, benzophenone-based, ketal-based, and acetophenone-based initiators, and may be used alone or in combination.

Specifically, 2,2-dimethyl-2-hydroxy-acetophenone, 1-hydroxy-1-cyclohexyl-phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 1-methyl-1- {4- (methylthio) phenyl} -2-morpholino-propan-1-one, 2,4,6-trimethylbenzyl-diphenyl-phosphine Oxide, 1-chloro-4-propoxythioxanthone, isoprolylthioxanthone (mixture of 2- and 4-isomers), benzophenone, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and 1 -Phenyl-2-hydroxy-2-hydroxy-2-methylpropano Blend with bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and 1-hydroxy-cyclohexyl-phenyl ketone, bis (2,4,6-trimethylbenzoyl) phenylphosphine Oxide and camphorquinone.

中 で も Among them, it is preferable to select a photopolymerization initiator that has good compatibility with the reactive oligomer and / or reactive prepolymer and reactive diluent, has low odor, and does not react with natural light.

助 In addition, an auxiliary agent such as a sensitizer can be used in combination to accelerate the initiation reaction of the photopolymerization initiator.

顔料 As the coloring component used in the ultraviolet curable ink of the present invention, any of pigments and dyes can be used. When weather resistance and light fastness are required for a recorded matter recorded by printing, it is preferable to use a pigment, and any of organic and inorganic pigments is selected.

For example, organic pigments include nitrosos, dyed lakes, azo lakes, insoluble azos, monoazos, disazos, condensed azos, benzimidazolones, phthalocyanines, anthraquinones, perylenes, quinacridones, dioxazines , Isoindolines, azomethines, pyrrolopyrroles and the like.

Examples of inorganic pigments include oxides, hydroxides, sulfides, ferrocyanides, chromates, carbonates, silicates, phosphates, carbons (carbon black), and metal powders. And the like.

染料 Further, when the weather resistance and the light resistance are not so important, a dye can be used, and the dye at that time is not particularly limited, and an arbitrary dye is selected.

For example, dyes include azos, anthraquinones, indigoids, phthalocyanines, carboniums, quinone imines, methines, xanthenes, nitros, and oil-soluble dyes such as nitrosos, disperse dyes, acid dyes, reactive dyes. Cation dyes and direct dyes.

In addition, additives such as a dispersant, a heat stabilizer, an antioxidant, a preservative, an antifoaming agent, and a penetrant can be added to the ultraviolet-curable ink composition as needed.

The ultraviolet-curable ink of the present invention is a coloring material, a resin, if necessary, and other additives are mixed, and the mixture is further dispersed using a dispersing machine such as a roll mill, a ball mill, a colloid mill, a jet mill, and a bead mill. Can be obtained by performing filtration.

The viscosity at 25 ° C. of the ultraviolet curable ink of the present invention comprising the above components is preferably from 40 to 800 cps, more preferably from 60 to 800 cps, further preferably from 80 to 400 cps, and particularly preferably from 100 to 200 cps. If the viscosity at 25 ° C. is lower than 40 cps, the content of the reactive oligomer and / or reactive prepolymer tends to decrease, and it becomes difficult to obtain sufficient performance with respect to scratch resistance and adhesion resistance, and exceeds 800 cps. Thus, even when heated, the ink viscosity does not sufficiently decrease, resulting in ink lacking in ejection properties. Further, the viscosity at 60 ° C. is preferably 5 to 80 cps.

記録 The recording of an image on the flexible base material of the ultraviolet curable ink includes letterpress printing, planographic printing, gravure printing, screen printing, ink jet printing, and the like.

Among them, ink jet printing, which allows fine expression of images and small lot processing, which is difficult with conventional printing methods, is preferable.

イ ン ク ジ ェ ッ ト There is no particular limitation on the inkjet printing apparatus using the ultraviolet curable ink. The viscosity at the time of ink ejection is preferably 1 to 100 cps, and more preferably 5 to 50 cps.

ヘ ッ ド A head used in the ink jet system may be equipped with a heating device to lower the viscosity by heating and discharge the ink. According to this method, the ink can be heated and used, so that the reactive oligomer and / or the reactive prepolymer can be added at a high level. In consideration of the melt viscosity when heated, the addition amount is preferably in the range of 10 to 60%, and the adhesion to the substrate, the followability between the substrate and the cured film, the scratch resistance of the cured film, and the like are considered. It is possible to change it arbitrarily within the range.

加熱 There is no particular limitation on a heatable inkjet printing apparatus using an ultraviolet curable ink. A head provided in a general inkjet printer may be provided with a heating device so that the viscosity is reduced by heating. The heating temperature is from room temperature to 150 ° C., preferably from 30 to 70 ° C. The heating temperature is determined in consideration of the curability to heat of the reactive oligomer and / or reactive prepolymer to be used, that is, the heating temperature is set lower than the temperature at which curing starts due to heat. Further, the viscosity of the ink at the time of ejection under heating is preferably 1 to 100 cps, more preferably 5 to 50 cps.

(5) As the conditions for ultraviolet irradiation, the voltage of the ultraviolet lamp is preferably 50 to 280 W / cm, and more preferably 120 to 200 W / cm. If the voltage of the ultraviolet lamp is lower than 50 W / cm, the ink tends not to be sufficiently cured due to insufficient peak intensity of the ultraviolet light and the insufficient integrated light amount, and if the voltage is higher than 280 W / cm, the flexible substrate (film) is formed of the ultraviolet lamp. , And the cured film of the ink tends to deteriorate.

The irradiation time of the ultraviolet ray is preferably 0.1 to 20 seconds, more preferably 0.5 to 10 seconds. If the irradiation time of the ultraviolet lamp is longer than 20 seconds, the flexible substrate (such as a film) tends to be deformed or melted by the heat of the ultraviolet lamp, and the cured film of the ultraviolet-curable ink tends to deteriorate. If the time is shorter than the second, the integrated light amount of the ultraviolet light is insufficient, and the ultraviolet curable ink tends not to be sufficiently cured.

記録 The recording medium used in the present invention is not particularly limited, but is preferably a flexible substrate. For example, resin films, metal foils, fibers, papers and the like can be mentioned.

印 When printing using the ultraviolet curable ink of the present invention, these recording media are not usually treated, but if necessary, pretreatment such as primer treatment can be performed.

Next, the present invention will be described with reference to examples, but the present invention is not necessarily limited to the examples.

Example 1
20 parts by weight of Ebecryl 8402 (reactive oligomer; urethane acrylate, difunctional, Tg = 14 ° C., viscosity at 800 ° C. at 60 ° C., 800 cps, manufactured by Daicel UCB) as an ultraviolet curable ink, SR-268 (reactive diluent) 73.7 parts by weight of tetraethylene glycol diacrylate, bifunctional, Tg = 23 ° C., manufactured by Sartomer Co., 1 part by weight of HOSTAPERM PINK E-02 (quinacridone red, manufactured by Clariant Japan KK) as a colorant and dispersion 0.3 parts by weight of Floren DOPA-33 (modified acrylic copolymer, manufactured by Kyoeisha Chemical Co., Ltd.) as an agent, and Darocure 1173 (2-hydroxy-2-methyl-1-phenyl-propane-) as a photoinitiator. ON, Ciba Specialty Chemicals Co., Ltd.) 5 weight It was added, and dispersed using a bead mill disperser, was then filtered to remove impurities performed, to prepare a homogeneous magenta ultraviolet-curable ink. When the viscosity of this ink was measured, it was 46.7 cps at 25 ° C. and 13.1 cps at 60 ° C.

イ ン ク ジ ェ ッ ト An ink jet printer head and an ultraviolet lamp were used as a method for applying and curing the ink on the recording medium.

印 The printing conditions and the UV irradiation conditions are as follows. An acrylic film (transparent, 50 μm in thickness) was used as an attachment. After the image was printed and cured by ultraviolet irradiation, the cured film was tested for scratch resistance according to the test method of JIS K5400. In addition, as a result of performing a cellophane tape peeling test on the adhesiveness, it was good without any peeling. As a result of conducting a curl test for flexibility, the cured film was good without any cracking or peeling off.

ノ ズ ル Further, nozzle clogging was confirmed after printing in ink dischargeability, but no nozzle clogging was confirmed.

(Printing conditions)
B) Nozzle diameter: 70 (μm)
B) Applied voltage: 50 (V)
C) Pulse width: 20 (μs)
D) Driving frequency: 1 (kHz)
E) Resolution: 180 (dpi)
F) Heating temperature: 60 (° C)

[UV irradiation conditions]
A) Lamp type: Metal halide lamp i) Voltage: 120 W / cm
U) Irradiation time: 1 second
E) Irradiation height: 10 (cm)

〔Evaluation test〕
A) Scratch resistance: JIS K5400 (84.2 manual scraping method)
No damage at H hardness or higher ... (○)
No damage due to HB hardness ... (△)
Scratched below HB hardness ... (×)
B) Adhesiveness: Adhere cellophane tape to the cured film and peel off vigorously, and check the state afterwards. The cured film does not peel off from the substrate and no change in the film surface is observed.
The cured film does not peel off from the substrate, but the surface of the film becomes slightly uneven ... (△)
The cured film is completely peeled off ... (×)
U) Followability: Cured the flexible substrate (film / metal foil) on which the image was recorded and confirmed the state of the cured film. The cured film did not crack and did not peel off from the substrate.
Cracks occur in the cured film ... (△)
The cured film cracks and peels off from the substrate ... (×)

Example 2
20 parts by weight of Ebecryl 450 (reactive oligomer; polyester acrylate, hexafunctional, Tg = 17 ° C., viscosity at 60 ° C., 410 cps, manufactured by Daicel UCB) as an ultraviolet curable ink, SR-268 (reactive diluent) 73.7 parts by weight of tetraethylene glycol diacrylate, bifunctional, Tg = 23 ° C., manufactured by Sartomer Co., 1 part by weight of HOSTAPERM PINK E-02 (quinacridone red, manufactured by Clariant Japan KK) as a colorant and dispersion 0.3 parts by weight of Floren DOPA-33 (modified acrylic copolymer, manufactured by Kyoeisha Chemical Co., Ltd.) as an agent, and Darocure 1173 (2-hydroxy-2-methyl-1-phenyl-propane-) as a photoinitiator. ON, Ciba Specialty Chemicals Co., Ltd.) Parts was added and dispersed in the same manner as in Example 1. was then filtered to remove impurities performed, to prepare a homogeneous magenta ultraviolet-curable ink. When the viscosity of this ink was measured, it was 32.1 cps at 25 ° C. and 9.6 cps at 60 ° C.

イ ン ク ジ ェ ッ ト An ink jet printer head and an ultraviolet lamp were used as a method for applying and curing the ink on the recording medium.

The printing conditions and the irradiation conditions of the ultraviolet rays are the same as in the first embodiment. After the image was printed and cured by ultraviolet irradiation, the cured film was tested for scratch resistance according to the test method of JIS K5400. In addition, as a result of performing a cellophane tape peeling test on the adhesiveness, it was good without any peeling. As a result of conducting a curl test for flexibility, a slight crack was observed in the cured film, but no peeling was observed.

ノ ズ ル Further, nozzle clogging was confirmed after printing in ink dischargeability, but no nozzle clogging was confirmed.

Example 3
30 parts by weight of an ultraviolet curable ink, CN-981 (reactive oligomer; urethane acrylate, bifunctional, Tg = 22 ° C., viscosity at 60 ° C., 6190 cps, manufactured by Sartomer Co.), SR-268 (reactive diluent; tetraethylene 63.7 parts by weight of glycol diacrylate, bifunctional, Tg = 23 ° C., manufactured by Sartomer), 1 part by weight of HOSTAPERM PINK E-02 (quinacridone red, manufactured by Clariant Japan KK) as a colorant and Floren as a dispersant 0.3 parts by weight of DOPA-33 (modified acrylic copolymer, manufactured by Kyoeisha Chemical Co., Ltd.) and Darocure 1173 (2-hydroxy-2-methyl-1-phenyl-propan-one, Ciba as a photoinitiator) 5 parts by weight of Specialty Chemicals Co., Ltd.) Machine were dispersed using was then filtered to remove impurities performed, to prepare a homogeneous magenta ultraviolet-curable ink. When the viscosity of this ink was measured, it was 110.0 cps at 25 ° C. and 21.4 cps at 60 ° C.

イ ン ク ジ ェ ッ ト An ink jet printer head and an ultraviolet lamp were used as a method for applying and curing the ink on the recording medium.

印 The printing conditions and the UV irradiation conditions are as follows. An acrylic film (transparent, 50 μm in thickness) was used as an attachment. After the image was printed and cured by ultraviolet irradiation, the cured film was tested for scratch resistance according to the test method of JIS K5400. In addition, as a result of performing a cellophane tape peeling test on the adhesiveness, it was good without any peeling. As a result of conducting a curl test for flexibility, the cured film was good without any cracking or peeling off.

ノ ズ ル Further, nozzle clogging was confirmed after printing in ink dischargeability, but no nozzle clogging was confirmed.

Comparative Example 1
20 parts by weight of a UV-curable ink, CN-965 (reactive oligomer; urethane acrylate, bifunctional, Tg = -37 ° C., viscosity 9975 cps at 60 ° C., manufactured by Sartomer Co.), SR-268 (reactive diluent; tetra 73.7 parts by weight of ethylene glycol diacrylate, bifunctional, Tg = 23 ° C., manufactured by Sartomer Co., 1 part by weight of HOSTAPERM PINK E-02 (quinacridone red, manufactured by Clariant Japan KK) as a colorant and as a dispersant 0.3 parts by weight of Floren DOPA-33 (modified acrylic copolymer, manufactured by Kyoeisha Chemical Co., Ltd.), and Darocure 1173 (2-hydroxy-2-methyl-1-phenyl-propan-one as a photoinitiator) 5 parts by weight (manufactured by Ciba Specialty Chemicals Co., Ltd.) Dispersed in such a way, it was then filtered to remove impurities performed, to prepare a homogeneous magenta ultraviolet-curable ink. When the viscosity of this ink was measured, it was 73.4 cps at 25 ° C. and 18.5 cps at 60 ° C.

イ ン ク ジ ェ ッ ト An ink jet printer head and an ultraviolet lamp were used as a method for applying and curing the ink on the recording medium.

The printing conditions and the irradiation conditions of the ultraviolet rays are the same as in the first embodiment. After the image was printed and cured by ultraviolet irradiation, the cured film was tested for scratch resistance according to the test method of JIS K5400. As a result, the cured film became less than HB hardness and was damaged. As a result of a cellophane tape peeling test for adhesiveness, there was no peeling, but the film surface was somewhat uneven. As a result of conducting a curl test for flexibility, the cured film was good without any cracking or peeling off.

ノ ズ ル Further, nozzle clogging was confirmed after printing in ink dischargeability, but no nozzle clogging was confirmed.

Comparative Example 2
20 parts by weight of Ebecryl 8402 (reactive oligomer; urethane acrylate, bifunctional, Tg = 14 ° C., viscosity at 60 ° C., 800 cps, manufactured by Daicel UCB Co., Ltd.) as an ultraviolet curable ink, M-270 (reactive diluent) 73.7 parts by weight of polypropylene glycol diacrylate, bifunctional, Tg = −32 ° C., manufactured by Toa Gosei Co., Ltd., and 1% by weight of HOSTAPERM PINK E-02 (quinacridone red, manufactured by Clariant Japan KK) as a colorant. Parts and 0.3 parts by weight of Floren DOPA-33 (modified acrylic copolymer, manufactured by Kyoeisha Chemical Co., Ltd.) as a dispersant, and Darocure 1173 (2-hydroxy-2-methyl-1-phenyl) as a photoinitiator. -Propane-on, Ciba Specialty Chemicals Co., Ltd.) Parts was added and dispersed in the same manner as in Example 1. was then filtered to remove impurities performed, to prepare a homogeneous magenta ultraviolet-curable ink. When the viscosity of this ink was measured, it was 175 cps at 25 ° C. and 33.5 cps at 60 ° C.

イ ン ク ジ ェ ッ ト An ink jet printer head and an ultraviolet lamp were used as a method for applying and curing the ink on the recording medium.

The printing conditions and the irradiation conditions of the ultraviolet rays are the same as in the first embodiment. After the image was printed and cured by ultraviolet irradiation, the cured film was tested for scratch resistance according to the test method of JIS K5400. As a result, the cured film became less than HB hardness and was damaged. As a result of a cellophane tape peeling test for adhesiveness, there was no peeling, but the film surface was somewhat uneven. As a result of conducting a curl test for flexibility, the cured film was good without any cracking or peeling off.

ノ ズ ル Further, nozzle clogging was confirmed after printing in ink dischargeability, but no nozzle clogging was confirmed.

Comparative Example 3
20 parts by weight of Ebecryl 8402 (a reactive oligomer; urethane acrylate, bifunctional, Tg = 14 ° C., viscosity at 60 ° C., 800 cps, manufactured by Daicel UCB) as an ultraviolet curable ink, 20 parts by weight of light acrylate NP-A (reactive Diluent: 73.7 parts by weight of neopentyl glycol diacrylate, bifunctional, Tg = 117 ° C., manufactured by Kyoeisha Chemical Co., Ltd .; HOSTAPERM PINK E-02 (quinacridone red, manufactured by Clariant Japan KK) as a colorant 1 part by weight, 0.3 part by weight of Floren DOPA-33 (modified acrylic copolymer, manufactured by Kyoeisha Chemical Co., Ltd.) as a dispersant, and Darocure 1173 (2-hydroxy-2-methyl-1) as a photoinitiator. -Phenyl-propan-one, Ciba Specialty Chemical Ltd.) 5 parts by weight was added and dispersed in the same manner as in Example 1, was then filtered to remove impurities performed, to prepare a homogeneous magenta ultraviolet-curable ink. When the viscosity of this ink was measured, it was 21.3 cps at 25 ° C. and 8.7 cps at 60 ° C.

イ ン ク ジ ェ ッ ト An ink jet printer head and an ultraviolet lamp were used as a method for applying and curing the ink on the recording medium.

The printing conditions and the irradiation conditions of the ultraviolet rays are the same as in the first embodiment. After the image was printed and cured by ultraviolet irradiation, the cured film was tested for scratch resistance according to the test method of JIS K5400. In addition, as a result of performing a cellophane tape peeling test for adhesiveness, the cured film was peeled off from the substrate. As a result of conducting a curl test for flexibility, the cured film was cracked and peeled off from the substrate.

ノ ズ ル Further, nozzle clogging was confirmed after printing in ink dischargeability, but no nozzle clogging was confirmed.

Results of scratch resistance, adhesion, and follow-up tests for Examples 1 to 3 and Comparative Examples 1 to 3, and Tg of a polymer of a reactive oligomer and / or a reactive prepolymer alone, a reactive diluent alone Table 1 shows the Tg of the polymer.

From the results in Table 1, in order to satisfy the fastness, a reactive oligomer and / or a reactive prepolymer having a glass transition point (Tg) in the range of −25 to 70 ° C. and a reactive diluent are used. It is also preferable that urethane acrylate and polyester acrylate are preferable.

Claims (2)

An ultraviolet curable ink comprising a coloring component, a reactive oligomer and / or a reactive prepolymer, a reactive diluent, and a photopolymerization initiator, wherein a polymer of the reactive oligomer and / or the reactive prepolymer alone is provided. UV curable ink having a glass transition point of -25 to 70 ° C. for both the glass transition point and the polymer of the reactive diluent alone. 2. The ultraviolet curable ink according to claim 1, wherein the difference between the glass transition point of the polymer of the reactive oligomer and / or the reactive prepolymer alone and the glass transition point of the polymer of the reactive diluent alone is within 30 ° C. .