JP2007056232A - Active energy ray-curable ink for inkjet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy ray-curable ink for inkjet, providing a printed product having excellent adhesion and processability to and of a plastic base material practically requiring bending and elongation processability, and also having excellent hardness of the formed film. <P>SOLUTION: The active energy ray-curable ink for inkjet comprises a polymerizable monomer. The polymerizable monomer comprises 40-90 wt.% phenoxyethyl acrylate, 0.01-30 wt.% vinylcaprolactam and 0.01-30 wt.% 2-hydroxy-3-phenoxypropyl acrylate based on the whole monomer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an active energy ray-curable ink for an ink jet which is excellent in processability and excellent in high hardness, cosmetics and adhesion. The ink of the present invention is suitable for interior and exterior printing applications that require cosmetics by processing, printing applications for CDs, DVDs, etc., and printing on non-permeable substrates such as printing on flexible substrates. Is suitable.

  Conventionally, active energy ray curable inks have been supplied and used for offsets, silk screens, top coats, etc., but from the merits such as cost reduction by simplifying the drying process and reduction of solvent volatilization as an environmental response. The amount used has increased in recent years. Among them, water-based and solvent-based inks are often used as ink-jet inks, and the use is properly used according to each feature, but for industrial use, there are limitations on the receiving substrate, relatively poor water resistance, There are problems such as high ink drying energy and adhesion of ink components to the head due to drying, and replacement with active energy ray-curable ink with relatively low volatility is expected.

  However, cured films using conventional active energy curable inks often exhibit hard but brittle properties. In addition, a cured film in which Tg is simply lowered to room temperature or lower is excellent in flexibility such as bending, but on the other hand, the scratch resistance and friction resistance due to extremely reduced hardness are reduced. It becomes difficult to use as the above handling or as the quality of the product itself. All active energy ray cured films are greatly inferior to conventional solvent-based inks in terms of stretch processing characteristics. As a result, in high-grade applications that require molding processing, there is no major switchover, although substitution is expected. Is the current situation. This situation is also the same with the current active energy ray-curable ink jet ink. However, in order to stably discharge with the ink jet, it is necessary to suppress the viscosity to about several tens of cps at the highest, and to reduce the head member. Since it is necessary to selectively use a monomer that does not erode, the actual compounded monomer is very limited. As a result, no ink that satisfies many required properties has been put on the market.

  In order to solve such a problem, by blending phenoxyethyl acrylate, vinyl caprolactam, 2-hydroxy-3-phenoxypropyl acrylate in the ratio described in the present invention, the viscosity stability is good, the adhesiveness is excellent, In addition, it has become possible to provide ink for ink jets having stretch processability. In addition, by adding isobornyl acrylate in order to impart scratch resistance, an ink capable of forming a coating film that can sufficiently withstand the processing steps and has sufficient hardness as a product has been provided. Furthermore, by selectively using a low molecular weight monomer, it was possible to suppress the generation of satellite droplets that are likely to occur during ejection, and to print a printed material with excellent cosmetic properties for a long time.

  As a solventless active energy ray curable ink jet ink, Patent Document 1 discloses a dye and 50 to 95% of a polymerizable monomer, a maximum of 70% by weight of a monofunctional monomer, a maximum of 70% by weight of a bifunctional monomer, 0 Disclosed is a 10% by weight monomer-based ink jet ink having a functionality of 3 or more.

The composition of the monofunctional monomer up to 70% by weight means that it contains 30% by weight or more of polyfunctional monomer and uses many polyfunctional monomers with large cure shrinkage, so it is not suitable for practical use due to poor adhesion to polycarbonate and polyester substrates. It was not.
Patent Document 2 discloses an ink composition composed of monomers having an alkoxylated component and a non-aromatic heterocyclic component as adhesive components. Although this ink had good adhesion to the polycarbonate substrate and good flexibility, the substrate adhesion of the coating film was deteriorated in the weather resistance test. This is presumably because the alkoxylation component absorbed water and caused floating at the coating film / substrate interface. This phenomenon is particularly noticeable with lower alkoxy groups. Patent Document 3 discloses an ink composition composed of a monofunctional or higher polyester urethane oligomer having a polycaprolactone ester component and a hydroxyl component and a reactive diluent in order to alleviate shrinkage during curing. This ink has adhesion and flexibility with urethane oligomer components, and the viscosity is adjusted to a predetermined range with a reactive diluent, but the viscosity is high and the temperature temperature dependence is relatively large, and there is a problem with ink jet suitability. Remains. Further, since a necessary amount of the oligomer component is added, it is necessary to select a low-viscosity reactive diluent such as tetrahydrofurfuryl acrylate, and there are many problems such as the use period of the head is shortened due to the erosion of the head peripheral member and the cost is increased. Patent Document 4 presents an ultraviolet curable ink excellent in adhesion to polycarbonate and processability. However, this ink has a high viscosity because it uses a polyurethane-based oligomer, and is very ejected by an ink jet. Can not. In addition, even when the viscosity is lowered to a level that allows ejection, the phenomenon of ink stringing due to the high molecular weight component of the polyurethane-based oligomer appears during ink ejection, causing stains. Cannot be used above. In addition, the polycaprotactic urethane acrylate synthesized by the method described in this document becomes a bifunctional oligomer because hydroxyacrylate can be added to the —NCO groups attached to both ends of urethane prepared in advance. In this document, post-processability is imparted by the flexibility and adhesiveness of urethane, but as a result of adding a large amount of bifunctional monomer, it is possible to cope with slight stretching. The stretch workability as large as described in the invention cannot be obtained.

Japanese Patent Laid-Open No. 5-214280 JP-T-2004-514014 JP-T-2004-518787 JP-A-6-184484

  INDUSTRIAL APPLICABILITY The present invention provides an active energy ray curing for ink jets that can obtain a printed matter that is excellent in adhesion and workability to a plastic substrate that requires practical bending and stretching performance, and excellent in the hardness of the formed film. The purpose is to provide mold ink.

That is, the present invention is an active energy ray-curable ink for an ink jet containing a polymerizable monomer,
The polymerizable monomer is 40% to 90% by weight of phenoxyethyl acrylate, 0.01% to 30% by weight of vinylcaprolactam, and 0.01% by weight of 2-hydroxy-3-phenoxypropyl acrylate to the whole monomer. The present invention relates to an active energy ray-curable ink for an ink jet, characterized by containing from 30% to 30% by weight.

  The present invention further relates to the above active energy ray-curable ink, wherein the polymerizable monomer contains 0.01% by weight to 30% by weight of isobornyl acrylate with respect to the whole monomer.

  The present invention also relates to the above active energy ray-curable ink, wherein the polymerizable monomer does not contain a monomer having a molecular weight of 2000 or more.

  Moreover, this invention relates to the printed matter formed by printing on the printing base material with the said active energy ray hardening-type ink.

The active energy ray-curable ink for an ink jet of the present invention is capable of obtaining a printed material having excellent stretch processability and excellent in cosmetic properties, adhesion, and hardness of a coating film. It can be suitably used for printing or for applications where deformation processing is performed after ink jet printing.

In the active energy ray-curable ink according to the present invention, the cured coating film after ink jet discharge onto various substrates has not only adhesion to the substrate but also high hardness, and in molding processing such as stretching. Phenoxyethyl acrylate is 40% to 90% by weight, and vinylcaprolactam is 0.01% to 30% by weight as a composition for extending the coating film, flexibility, adhesion after processing, and cosmetics of printed matter. It was found that it was important to contain 0.01% to 30% by weight of 2-hydroxy-3-phenoxypropyl acrylate.
Further, by containing 0.01% to 30% by weight of isobornyl acrylate, a coating film having higher hardness could be formed.
Moreover, long-term stability of printing could be ensured by not blending a monomer having a molecular weight of 2000 or more.

Although it is a function of each monomer in the present invention, phenoxyethyl acrylate increases adhesion to a substrate and has appropriate ductility. Moreover, since vinylcaprolactam has high Tg, it can provide high hardness to a coating film. Furthermore, since the reactivity is excellent, blocking of the coating film is prevented. 2-Hydroxy-3-phenoxypropyl acrylate can impart ductility and flexibility to the coating film. Furthermore, since isobornyl acrylate also has a high Tg, it further increases the hardness of the coating film and slightly improves the ductility.
When the amount of phenoxyethyl acrylate was less than 40% by weight, the adhesion with the base material was inferior and practically unusable. Furthermore, when it contains more than 90 weight%, Tg of a coating film fell remarkably and the coating-film hardness in normal temperature became low, and it was not practical.
If more than 30% by weight of vinylcaprolactam is blended, the stability of the viscosity will deteriorate, and if it is ejected with an ink jet, the dot shape will change and printing will not be reproduced. It became. On the other hand, when vinyl caprolactam is not blended, the occurrence of blocking due to the decrease in Tg, or the hardness of the coating film decreases, and the scratching property deteriorates. In addition, when the content of 2-hydroxy-3-phenoxypropyl acrylate was more than 30% by weight, the adhesion to the substrate was deteriorated. Furthermore, ductility deteriorated when 2-hydroxy-3-phenoxypropyl acrylate was not blended.
Moreover, when isobornyl acrylate was blended, the coating film hardness increased due to the effect of increasing Tg, and a coating film with more excellent scratch resistance could be formed. Furthermore, isobornyl acrylate has a low viscosity, resulting in an increase in the degree of freedom in selecting a polyfunctional monomer. However, when more than 30% by weight of isobornyl acrylate is blended, the adhesion to the base material is inferior, making it practically unusable.

  Conventionally, when a function such as adhesion or flexibility is imparted to an ink, a relatively high molecular weight monomer, oligomer, or inert resin is often added. However, according to the present invention, when a component having a molecular weight of 2000 or more is blended, it is found that a stringing phenomenon occurs when an ink jet is ejected for a long time, which may impair the cosmetics of the printed matter. I understood.

  In the present invention, in addition to blending phenoxyethyl acrylate, vinyl caprolactam, 2-hydroxy-3-phenoxypropyl acrylate, and isobornyl acrylate in the stated ratio, a general polymerizable reaction monomer can be additionally blended. The polymerization reactive monomer specifically refers to a molecule having an ethylenically unsaturated double bond. This polymerization-reactive monomer does not contain components such as initiators, pigments and additives described below.

  In addition, the general polymerizable reaction monomer described in the present invention specifically includes ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and 1,6-hexanediol. Di (meth) acrylate, ethoxylated 1,6-hexanediol diacrylate, neopentyl glycol di (meth) acrylate, polypropylene glycol diacrylate, 1,4-butanediol di (meth) acrylate, 1,9-nonanediol di Acrylate, tetraethylene glycol diacrylate, 2-n-butyl-2-ethyl-1,3-propanediol diacrylate, dimethylol-tricyclodecane diacrylate, neopentyl glycol diacrylate hydroxypivalate 1,3-butylene glycol di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, propoxylated bisphenol A di (meth) acrylate, cyclohexanedimethanol di (meth) acrylate, dimethylol dicyclopentane diacrylate , Trimethylolpropane triacrylate, hydroxypivalate trimethylolpropane triacrylate, ethoxylated phosphate triacrylate, ethoxylated tripropylene glycol diacrylate, neopentyl glycol modified trimethylolpropane diacrylate, stearic acid modified pentaerythritol diacrylate, penta Erythritol triacrylate, tetramethylolpropane triacrylate, tetramethylolmethane triacrylate Rate, pentaerythritol tetraacrylate, caprolactone-modified trimethylolpropane triacrylate, ethoxylated isocyanuric acid triacrylate, tri (2-hydroxyethyl isocyanurate) triacrylate, propoxylate glyceryl triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol tetra Acrylate, ditrimethylolpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, neopentyl glycol oligoacrylate, 1,4-butanediol oligoacrylate relay 1,6-hexanediol oligoacrylate, trimethylolpropane oligoacrylate, pentaerythritol oligoacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, isobutyl acrylate, t-butyl acrylate, isooctyl Acrylate, cyclohexyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, 3-methoxybutyl acrylate, benzyl acrylate, ethoxyethoxyethyl acrylate, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, Methoxydipropylene glyco Acrylate, methylphenoxyethyl acrylate, dipropylene glycol acrylate, β-carboxyl ethyl acrylate, ethyl diglycol acrylate, trimethylolpropane formal monoacrylate, 4-t-butylcyclohexyl acrylate, tri (meth) allyl isocyanurate, imide acrylate, Isoamyl acrylate, ethoxylated succinic acid acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, tribromophenyl acrylate, ethoxylated tribromophenyl acrylate, trifluoroethyl acrylate, ω-carboxypolycaprolactone monoacrylate, acryloylmorpholine, ethoxylated neopentyl glycol di (Meth) acrylate, propoxylated neope Tyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, phenoxydiethylene glycol acrylate, vinylpyrrolidone, N-vinylformamide, 1,4-cyclohexane Although dimethanol monoacrylate etc. are mentioned, it is not limited to this. These compounds may be used alone or in combination of two or more as required.

In the present invention, the above-described monofunctional monomer, bifunctional monomer, or other monomer having a bifunctional or higher functional group can be used.
These polymerizable monomers are preferably monomers having a molecular weight of less than 2000 in order to finish as a low-viscosity ink or to ensure long-term printing image stability, and monomers having a molecular weight of 2000 or more as the polymerizable monomer. It is more preferable not to contain.

  In the present invention, the Martens hardness value was used as a method for measuring hardness. When evaluating the hardness of a coating film, in addition to the material properties of the coating film itself, the material of the substrate to be coated, the adhesion between the substrate and the coated material, the coating film thickness, etc. are very important. The Martens hardness calculated from the depth and load of the indenter slightly entering the film surface has recently been standardized as a means for relatively measuring the hardness of the coating itself, including the DIN standard. In the present invention, the Martens strength is used as a measure for measuring the strength of the coating film itself. In the present invention, a microhardness tester is used to measure the Martens hardness value. However, the method for measuring the Martens hardness is not limited to this, and it may be obtained by a measuring device generally called “nanoindentator” or other methods.

  The active energy ray described in the present invention affects an electron orbit of an irradiated object such as an electron beam, an ultraviolet ray, and an infrared ray, and indicates an energy ray that can trigger a polymerization reaction such as a radical, a cation, and an anion. The energy ray is not limited to this as long as it induces a polymerization reaction.

The ink shown by this invention shows the liquid printed or applied to the base-material surface.
When this ink does not contain a coloring component, it can be used as a coating application, and it can also be used as a single coating layer or laminated coating with an ink containing a colorant described below. Various fillers and resin components can also be added to impart durability such as hardness and scratch resistance of the cured film, moldability, and design properties such as gloss control. Examples of the filler include extender pigments such as calcium carbonate, barium sulfate, spherical silica, and hollow silica, and resin beads. The resin component is not particularly limited as long as the resin is inactive to active energy rays. , Polyurethane resin, vinyl chloride resin (eg, polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer), polyester resin, poly (meth) acrylic resin, polyketone resin, polyvinyl resin (For example, polyvinyl acetal resin, polyvinyl butyral resin, polyvinyl pyrrolidone resin), cellulose resin (for example, CAB resin, CAP resin) and the like can be mentioned. When these fillers and resin components are added, it is preferable to consider the type and composition in consideration of ink jet aptitude, but other printing methods such as silk screen printing, gravure printing, offset printing, or spray coating. You may perform the coating by. In addition, in the multi-layer coating with the ink containing the colorant, the coating material used in general printing applications other than the ink of the present invention, for example, silk screen printing, gravure printing, offset printing, etc. includes the colorant of the present invention. Lamination may be performed on the ink layer, or a separately molded coating layer (such as a film) may be transferred by lamination, or lamination using a spray coating material or the like may be performed.
On the other hand, when the ink of the present invention contains a coloring component, it can be used as a material for displaying graphics, characters, photographs and the like. Conventionally, dyes and pigments have been widely used as the coloring component, but pigments are often used particularly in terms of weather resistance. Among the pigment components, specific examples of carbon black include “Special Black 350, 250, 100, 550, 5, 4, 4A, 6” “Printex U, V, 140 U, 140 V, 95, 90, 85, manufactured by Degussa. 80, 75, 55, 45, 40, P, 60, L6, L, 300, 30, 3, 35, 25, A, G ”,“ REGAL 400R, 660R, 330R, 250R ”“ MOGUL E, L ”manufactured by Cabot Corporation “MA7, 8, 11, 77, 100, 100R, 100S, 220, 230” manufactured by Mitsubishi Chemical Corporation “# 2700, # 2650, # 2600, # 200, # 2350, # 2300, # 2200, # 1000, # 990, # 980, # 970, # 960, # 950, # 900, # 850, # 750, # 650, # 52, # 50, # 4 , # 45, # 45L, # 44, # 40, # 33, # 332, # 30, # 25, # 20, # 10, # 5, CF9, # 95, and the like # 260 ". In the present invention, in yellow, magenta, cyan ink, or other colors such as white, pigments used in inks for general printing applications and paint applications can be used, such as color developability and light resistance. From this point, it can be selected as necessary.
The ratio of the pigment to the whole ink is 0.2 to 15 parts by weight for organic pigments such as yellow, magenta, cyan, and black with respect to 100 parts by weight of ink. In the case, it is preferable to mix in an arbitrary ratio of 5 to 40 parts by weight.

Further, the ink of the present invention can use a dispersant for stabilizing the dispersion of the filler and pigment, and other additives for imparting each function.
As the dispersing agent, there are various kinds of dispersing agents such as a high molecular weight dispersing agent and a low molecular weight dispersing agent, which can be selected according to the dispersibility. A pigment derivative can be used as a dispersion aid.
Moreover, as an additive, the conventionally used wettability adjusting agent, surface tension adjusting agent, antifoaming agent, slipping agent, antiblocking agent, ultraviolet ray preventing agent and the like can be used.
Any dispersant, dispersion aid, and additive can be selected according to the intended application, and none of them is limited in the present invention.

  Moreover, when ultraviolet rays are used as active energy rays, a photopolymerization initiator is contained in the ink. The photopolymerization initiator can be freely selected depending on the curing speed, the cured coating film properties, and the coloring material. Specifically, as the radical photopolymerization initiator, a molecular cleavage type or a hydrogen abstraction type is suitable for the present invention. Specific examples include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, benzyl, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino-1- (4- Morpholinophenyl) -butan-1-one, bis (2,4,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 1,2-octanedione, 1- (4- (phenylthio) -2,2- (O-benzoyloxime)) and the like are preferably used, and other molecular cleavage types include 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyldimethyl ketal, 2-hydroxy-2 -Methyl-1-phenylpropane-1-o 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one Moreover, benzophenone, 4-phenylbenzophenone, isophthalphenone, 4-benzoyl-4′-methyl-diphenyl sulfide, etc., which are hydrogen abstraction type photopolymerization initiators, can also be used in combination.

  For the photo radical polymerization initiator, as sensitizers, for example, trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, An amine that does not cause an addition reaction with the polymerizable component, such as N-dimethylbenzylamine and 4,4′-bis (diethylamino) benzophenone, can also be used in combination. Of course, it is preferable to select and use the radical photopolymerization initiator and the sensitizer, which are excellent in solubility in the ultraviolet curable compound and do not inhibit the ultraviolet transmittance.

  In the present invention, a polymerization inhibitor such as hydroquinone, p-methoxyphenol, t-butylcatechol, pyrogallol, and butylhydroxytoluene is used in order to increase the stability of the ink over time and the stability in the printing apparatus. It is preferable to mix 0.01 to 5% by weight in the ink.

  The active energy ray-curable inkjet ink of the present invention uses one or more additives such as a plasticizer, a surface conditioner, an ultraviolet light inhibitor, a light stabilizer, and an antioxidant such as dibutylhydroxytoluene as necessary. Can do.

  In addition, when an electron beam is used as an active energy ray, it can be adjusted as an electron beam curing ink by blending it excluding the initiator and sensitizer.

  The ink of the present invention is printed on a printing substrate by an ink jet discharge device. The printing substrate used in the present invention is not particularly limited, but is a plastic substrate such as polycarbonate, hard vinyl chloride, soft vinyl chloride, polystyrene, foamed polystyrene, PMMA, polypropylene, polyethylene, PET, or a mixed or modified product thereof, and Examples thereof include glass, metal substrates such as stainless steel, and wood.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not particularly limited to the examples. In the examples, “part” represents “part by weight”.

First, Pigment Dispersion A was prepared with the following composition. Hereinafter, a dispersion was prepared by adding a pigment and a dispersant to a monomer, stirring the mixture with a high-speed mixer or the like until uniform, and then dispersing the obtained mill base with a horizontal sand mill for about 1 hour.
・ Solspers 32000 (Lubrisol's pigment dispersant) 9 parts ・ Phenoxyethyl acrylate 61 parts

Also, Pigment Dispersion B was prepared with the following composition. The method for producing the dispersion was prepared by the same production method as that for Dispersion A.
・ Novoperm Yellow P-HG (Clariant Benzimidazolone Pigment) 35 parts ・ Solspers 24000 (Lubrisol Pigment Dispersant) 7 parts ・ Phenoxyethyl acrylate 58 parts

In addition, Pigment Dispersion C was prepared with the following composition. The method for producing the dispersion was prepared by the same production method as that for Dispersion A.
Hostaperm Red E5B02 (Clariant quinacridone pigment) 20 parts Solspers 24000 (Lubrisol pigment dispersion) 6 parts Phenoxyethyl acrylate 74 parts In addition, Pigment Dispersion D was prepared with the following composition. The method for producing the dispersion was prepared by the same production method as that for Dispersion A.
・ Special Black 350 (Degussa carbon black pigment) 30 parts ・ Solspers 32000 (Lubrisol pigment dispersion) 6 parts ・ Phenoxyethyl acrylate 64 parts

Also, Pigment Dispersion E was prepared with the following composition. The method for producing the dispersion was prepared by the same production method as that for Dispersion A.
-Taihke PF740 (Ishihara Sangyo Co., Ltd. Silica-treated 1.0%, Alumina-treated 2.0% white pigment) 40 parts-Azisper PB821 (Ajinomoto Fine Techno Co., Ltd. pigment dispersant) 2 parts-Phenoxyethyl acrylate 58 parts

Example 1
The raw materials in Table 1 were added from the top of the table with stirring. After stirring for 2 hours, it was confirmed that there was no undissolved residue, and filtration was performed with a membrane filter to remove coarse particles causing the clogging of the head, thereby preparing an ink. This ink was discharged onto a polycarbonate plate by an ink jet discharge device so as to have a film thickness of 10 μm. Immediately after the discharge, ultraviolet curing was performed at 120 W / cm from Harrison Toshiba Lighting, one high-pressure mercury lamp, a conveyor speed of 5 m / min, and 1 Pass to obtain a coating film. In addition, the viscosity of the prepared ink was measured on the day of preparation and after 30 days of standing at room temperature to confirm viscosity stability.
In addition, the printed matter printed on the polycarbonate was confirmed by visual observation or using an optical microscope.

Example 2 to Example 10
As in Example 1, ink was prepared as shown in Table 1, printed and cured to obtain a coating film.

Comparative Examples 1-7
As in Example 1, ink was prepared as shown in Table 1, printed and cured to obtain a coating film.

Evaluation Method The obtained coating film on polycarbonate is punched into a dumbbell shape together with the base material using a punching machine (manufactured by Dumbbell), and the obtained test piece is used using Tensilon (UCT-1T: manufactured by ORIENTEC). The sample was heated to 170 ° C., and the tensile test was performed together with the base material. Since the breaking point of the coating film was difficult to grasp from the change in tension obtained from the load cell, the elongation at the time when the breaking of the coating film surface was visually confirmed was expressed as%.

  The hardness of the coating film on the obtained polycarbonate was measured with a Fischer scope H100C (Fischer) hardness meter. The measurement was performed in a constant temperature room at 25 ° C. with an entry depth of 1 μm and an entry time of 30 seconds, and after three measurements, the Martens hardness value (HM) was obtained on average.

The printed matter on the obtained polycarbonate was evaluated visually or using an optical microscope as necessary.
The evaluation results were as follows: ○: Good dot formation Δ: Distortion occurred in dots ×: Evaluation was made such that satellites and stains other than dots were generated.

Adhesion to the substrate was achieved by applying cellophane tape to the part of the cured coating that had been cross-cut into 100 squares at 1 mm intervals, rubbing from the upper surface with an eraser, and sufficiently adhering the cellophane tape to the coated surface. Then, it was judged from the degree of adhesion of the coating film to the substrate when the cellophane tape was peeled at 90 °. The evaluation criteria are as follows.
◯: When no peeling is observed in 100 squares. Δ: When 100 squares remain in 100 squares, but damage is observed at the edge of the square. Δ: When 1-50 squares peel in 100 squares. Δ ×: 100 When 49 to 99 squares are peeled off in the mass ×: When 100 peels in 100 squares

  The viscosity of the ink prepared was measured at 25 ° C. by an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.) on the day and after 30 days at room temperature.

  The composition and evaluation results of the ink formulation are shown in Table 1.

  Examples 1 to 10 all showed good values for ductility, viscosity stability, substrate adhesion, printed matter appearance, and hardness, indicating that they can be used practically.

  Since Comparative Example 1 is blended with a small amount of phenoxyethyl acrylate, the substrate adhesion is poor and a sufficient function as a coating film cannot be obtained. Further, in Comparative Example 2, since the amount of phenoxyethyl acrylate is further small, the substrate adhesion is remarkably poor and cannot be used for most applications. In Comparative Example 3, as a result of adding a large amount of phenoxyethyl acrylate having a low Tg, the Tg was low and sufficient hardness as a coating film could not be obtained. In Comparative Example 4, in addition to the deterioration of the substrate adhesion due to the lack of phenoxyethyl acrylate, the deterioration of the viscosity stability due to the blending of a large amount of vinyl caprolactam was strongly observed, and as an ink jet application strict in viscosity management Could not be used. In Comparative Examples 5 and 6, deterioration of the substrate adhesion derived from the excessive blending of 2-hydroxy-3-phenoxypropyl acrylate or isobornyl acrylate was exhibited. In Comparative Example 7, by adding urethane acrylate having a molecular weight of 3400, the ductility was slightly improved. However, after printing for a long time, a stringing phenomenon occurred between the dots, and the cosmetic quality of the image was impaired. It was.

  In addition, after printing using the ink described in Example 1, the ductility of the printed material obtained by laminating and coating with the ink of Example 9 is 77%, and further, the substrate adhesion, the printed material appearance, and the hardness show good values, It showed necessary and sufficient performance for practical use. Furthermore, even if the ink described in Example 1 was replaced with any one of the inks described in Examples 2 to 8, and the ink described in Example 9 was replaced with the ink described in Example 10, practically sufficient performance was exhibited.

  The active energy ray curable ink for ink jet of the present invention is excellent in processability and excellent in high hardness, cosmetics, and adhesion. As a result, it is used for UV printing, which is conventionally difficult to process. In ink-jet printing with strict monomer regulations, the application could be greatly expanded. In particular, it is suitable for interior and exterior printing applications that require cosmetics by processing, printing applications for CDs, DVDs, etc., and printing on non-permeable substrates such as printing on flexible substrates.

Claims (4)

  An active energy ray-curable ink for an ink jet containing a polymerizable monomer, wherein the polymerizable monomer is 40% by weight to 90% by weight of phenoxyethyl acrylate and 0.01% by weight of vinyl caprolactam with respect to the whole monomer. An active energy ray-curable ink for an ink jet, comprising 30% by weight and 0.01% to 30% by weight of 2-hydroxy-3-phenoxypropyl acrylate.   The active energy ray-curable ink according to claim 1, wherein the polymerizable monomer further contains 0.01% by weight to 30% by weight of isobornyl acrylate based on the whole monomer.   3. The active energy ray-curable ink according to claim 1, wherein the polymerizable monomer does not contain a monomer having a molecular weight of 2000 or more. The printed matter formed by printing on the printing base material with the active energy ray hardening-type ink in any one of Claims 1-3.