JP2005112937A - Active ray-curing composition, and image forming method and inkjet recording device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active ray curing composition capable of high-speed cure to give the ease of handling, free of developing color mingling, and capable of recording a high definition image very stably, and to provide an image forming method and an inkjet recording device using it. <P>SOLUTION: The active ray-curing composition contains as photopolymerizable compounds a compound having an oxetane ring and a compound having an epoxy group represented by general formula (1) and in addition contains 0.1-10 mass%, based on the whole mass of the active ray-curing composition, of a diol structure represented by general formula (2). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an actinic ray curable composition capable of stably reproducing high-definition images on various recording materials, an image forming method using the composition, and an ink jet recording apparatus.

  In recent years, the inkjet recording method can easily and inexpensively create an image, and thus has been applied to various printing fields such as photographs, various printing, marking, and special printing such as a color filter. In particular, a recording device that emits and controls fine dots, ink that has improved color reproduction gamut, durability, and emission suitability, and ink absorbability, coloring material color development, surface gloss, etc. have been dramatically improved. It is also possible to obtain image quality comparable to silver halide photography using special paper. The image quality improvement of today's ink jet recording system is achieved only when all of the recording apparatus, ink, and special paper are available.

  However, in an inkjet system that requires dedicated paper, the recording medium is limited, and the cost of the recording medium increases. Therefore, many attempts have been made to record on a transfer medium different from dedicated paper by an ink jet method. Specifically, a phase change ink jet method using a wax ink solid at room temperature, a solvent ink jet method using an ink mainly composed of a fast-drying organic solvent, a UV ink jet method in which crosslinking is performed by ultraviolet (UV) light after recording, etc. It is.

  Among these, the UV inkjet method has been attracting attention in recent years because it has a relatively low odor compared to the solvent-based inkjet method, and can be recorded on a recording medium having no quick drying and no ink absorption. No. 200204 and JP 2000-504778 A disclose ultraviolet curable ink-jet inks.

  However, even if these inks are used, the dot diameter after landing greatly changes depending on the type of recording material and the working environment, and it is not possible to form high-definition images on various recording materials. Is possible.

  In particular, ultraviolet curable ink jet inks using cationically polymerizable compounds have been proposed (see, for example, Patent Documents 1 to 4), but these ultraviolet curable ink jet inks are not subject to oxygen inhibition. However, there is a problem that it is easily affected by moisture (humidity) at the molecular level. In addition, generation of wrinkles due to curing shrinkage becomes a problem depending on the curing environment.

  The image formation by the ultraviolet curable ink jet method is characterized in that a high-quality image can be obtained at low cost and that an image can be formed on a recording medium that does not absorb ink. However, there is a problem peculiar to this ink jet system. In the case of image formation on a recording medium that does not absorb ink, image deterioration due to mixing of the landed dots with adjacent dots is significant. This is a big problem especially in the case of high-definition image formation and between colors.

In the case of a general water-based ink jet method, this problem has been solved by improving the ink permeability to the recording medium by using an additive in special paper or ink, but the recording that does not absorb ink by the ultraviolet curable ink jet method At present, there is no solution for image formation on a medium. Further, in the case of high-speed printing, the formed image is often taken up, and quick curing is desired.
JP 2001-220526 A (Claims, Examples) JP 2002-188025 A (claims, examples) JP-A-2002-317139 (Claims, Examples) JP 2003-55449 A (claims, examples)

  The present invention has been made in view of the above-mentioned problems, and its purpose is an actinic ray capable of high-speed curing with easy handling, no color mixing, and highly stable recording of high-definition images. The object is to provide a curable composition, an image forming method using the same, and an ink jet recording apparatus.

The above object of the present invention has been achieved by the following constitution.
(Claim 1)
A compound having an oxetane ring as a photopolymerizable compound, a compound having an epoxy group represented by the general formula (1), and 0.1 to 10% by mass in general with respect to the total mass of the actinic ray curable composition An actinic ray curable composition containing a diol structure represented by formula (2).

(R ₁ represents an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted aromatic group, or an acyl group.)

(R ₂ represents an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted aromatic group, or an acyl group.)
(Claim 2)
The compound having a diol structure represented by the general formula (2) is a compound obtained by ring opening of a compound having an epoxy group represented by the general formula (1). Actinic ray curable composition.
(Claim 3)
The actinic ray curable composition according to claim 1 or 2, which contains a pigment.
(Claim 4)
The actinic ray curable composition according to claim 1, comprising an oil-soluble dye.
(Claim 5)
The actinic ray curable composition according to any one of claims 1 to 4, wherein the viscosity at 25 ° C is 7 to 50 mPa · s.
(Claim 6)
An actinic ray curable composition according to any one of claims 1 to 5 is jetted onto a recording material from an ink jet recording head and printing is performed on the recording material. An image forming method comprising irradiating actinic rays for 0.001 to 1 second after landing of a mold composition.
(Claim 7)
An actinic ray curable composition according to any one of claims 1 to 5 is jetted onto a recording material from an ink jet recording head and printing is performed on the recording material. An image forming method, wherein the total film thickness after landing of the mold composition and curing by irradiation with actinic rays is 2 to 25 μm.
(Claim 8)
An image forming method in which the actinic ray curable composition according to any one of claims 1 to 5 is jetted onto a recording material from an ink jet recording head, and printing is performed on the recording material, the ink jet recording head An image forming method, wherein the amount of droplets of the actinic ray curable composition discharged from each nozzle is 2 to 20 pl.
(Claim 9)
An image forming method in which the actinic ray curable composition according to any one of claims 1 to 5 is jetted onto a recording material from an ink jet recording head, and printing is performed on the recording material. An image forming method comprising forming an image by ejecting from a recording head.
(Claim 10)
It is an inkjet recording device used for the image forming method of any one of Claims 6-9, Comprising: It discharges, after heating actinic-light curable composition and a recording head to 35 to 100 degreeC. An inkjet recording apparatus.

  The present invention is an actinic ray curable composition that can be cured at high speed and can be easily handled, does not cause color mixing, and can record a high-definition image very stably, and an image forming method and an ink jet using the same A recording device could be provided.

  Hereinafter, the present invention will be described in detail.

  As the compound having an oxetane ring that can be used in the present invention, any known oxetane compound as introduced in JP-A Nos. 2001-220526 and 2001-310937 can be used.

The compound having an epoxy group represented by the general formula (1) will be described. In the formula, R ₁ represents an optionally substituted alkyl group having 1 to 10 carbon atoms (for example, an optionally substituted methyl group, ethyl group, propyl group, butyl group, isopropyl group, t-butyl group, hexyl group). Group, 2-ethylhexyl group, benzyl group, etc.), optionally substituted aromatic group (eg, optionally substituted phenyl group, naphthyl group, etc.), optionally substituted acyl group (eg, benzoyl) Group, methacryl group, stearyl group and the like, and an alkyl group is preferable.

  The addition amount of the compound having an epoxy group is preferably 10 to 80% by mass. If it is less than 10% by mass, the curability changes remarkably depending on the curing environment (temperature, humidity) and cannot be used. If it exceeds 80% by mass, the film physical properties after curing are weak and cannot be used. In the present invention, one type of alicyclic epoxy compound may be used alone, or two or more types may be used in appropriate combination.

  The production method of these compounds having an epoxy group is not limited. For example, Maruzen KK Publishing, 4th edition, Experimental Chemistry Course 20 Organic Synthesis II, 213, 1992, Ed. By Alfred Hasfner, The Chemistry of Heterocyclic compounds, Vol. 5, No. 5, No. 5, Y 42, 1986, Yoshimura, Adhesion, Vol. 30, No. 7, 42, 1986, JP-A Nos. 11-100308, 4-36263, 4-69360 and the like.

The compound having a diol group represented by the general formula (2) will be described. In the formula, R ₂ represents an optionally substituted alkyl group having 1 to 10 carbon atoms (for example, an optionally substituted methyl group, ethyl group, propyl group, butyl group, isopropyl group, t-butyl group, hexyl group). Group, 2-ethylhexyl group, benzyl group, etc.), optionally substituted aromatic group (eg, optionally substituted phenyl group, naphthyl group, etc.) or acyl group (eg, benzoyl group, methacryl group, stearyl). Group), and an alkyl group is preferable.

  The addition amount of the compound having a diol group is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass. If it exceeds 10% by mass, the curing rate decreases. If it is less than 0.1% by mass, the effect of addition cannot be obtained. The present inventors speculate that the compound having a diol group functions as a chain transfer agent in the curing reaction. Therefore, the active sites that have stopped functioning at the polymerization terminal are regenerated by the addition, but when the addition amount is large, the molecular weight of the polymer is small, which is the same as not being substantially cured. An added amount was obtained.

  The compound having a diol group of the present invention can be obtained by a conventionally known method, but a compound obtained by hydrolyzing the compound having an epoxy group with an acid or the like is preferable. It is expected that similar effects can be obtained with diols, but if they are obtained from the epoxy group, they have good compatibility with the epoxy compound in the composition and are added by phase separation or the like. No adverse effects occur.

  In the actinic ray curable composition of the present invention, when the viscosity at 25 ° C. is 7 to 50 mPa · s, the ejection from the inkjet head is stable regardless of the curing environment (temperature and humidity), and good curability. It is preferable to obtain

  The actinic ray curable composition of the present invention may contain various known pigments as a coloring material. The pigments that can be preferably used in the present invention are listed below.

C. I. Pigment Yellow-1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 109, 114, 120, 128, 129, 138 151, 154
C. I. Pigment Red-5, 7, 12, 22, 38, 48: 1, 48: 2, 48: 4, 49: 1, 53: 1, 57: 1, 63: 1, 101, 112, 122, 123, 144 146, 168, 184, 185, 202
C. I. Pigment Violet-19, 23
C. I. Pigment Blue-1, 2, 3, 15: 1, 15: 2, 15: 3, 15: 4, 18, 22, 27, 29, 60
C. I. Pigment Green-7, 36
C. I. Pigment White-6, 18, 21
C. I. Pigment Black-7
Further, as a specific example, as carbon black pigment, no. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B, Columbia-made Raven 700, Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Cabot's Regal 400R, Regal I330R, Regal I660R, Monar 80, Monar 80 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, Color Black FW1, Color Black FW2, Color Black FW18, Color Black FW18, Color Black FW18, Color Black FW18, Color Black FW18, Color Black FW18, Color Black FW18, Color Black FW18, Color Black FW18, Color Black FW18 or Black S170, Printex 35, Printex U, Printex V, Printex 140U, Printex 140V, Special Black 6, Special Black 40, Special Black 4A, Speck Maxsorb G-15, Maxsorb G-08, etc. can be used.

  In the present invention, it is preferable to use white ink in order to improve the color concealment property on a transparent substrate such as a plastic film. In particular, in soft packaging printing and label printing, it is preferable to use white ink, but since the discharge amount increases, the use amount is naturally from the viewpoint of the above-described discharge stability and the occurrence of curling and wrinkling of the recording material. There is a limit.

  For the dispersion of the pigment, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, paint shaker, or the like can be used. Further, a dispersing agent can be added when dispersing the pigment. As the dispersant, a polymer dispersant is preferably used, and examples of the polymer dispersant include Avecia's Solsperse series and Ajinomoto Fine-Techno's PB series. Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment. The dispersion medium is used using a solvent or a polymerizable compound. However, the radiation curable ink used in the present invention is preferably solvent-free because it reacts and cures immediately after ink landing. If the solvent remains in the cured image, the solvent resistance deteriorates and the VOC of the remaining solvent arises. Therefore, it is preferable in view of dispersibility that the dispersion medium is not a solvent but a polymerizable compound, and among them, a monomer having the lowest viscosity is selected.

  The pigment is preferably dispersed so that the average particle diameter of the pigment particles is 0.08 to 0.5 μm, and the maximum particle diameter is 0.3 to 10 μm, preferably 0.3 to 3 μm. The selection of the dispersion medium, the dispersion conditions, and the filtration conditions are appropriately set. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained. The pigment concentration is preferably 1% by mass to 10% by mass of the entire composition.

  The actinic ray curable inkjet ink composition of the present invention may contain various known dyes as a coloring material. The dyes that can be preferably used in the present invention are listed below. Various dyes such as azo dyes, azomethine dyes, quinone dyes, phthalocyanine dyes, and methine dyes can be used.

C. I. Solvent Yellow-1, 2, 3, 4, 14, 16, 19, 29, 56, 79, 82, 83, 88
C. I. Solvent Red-1, 18, 24, 27, 43, 51, 72, 73, 84, 132, 218
C. I. Solvent Violet-3
C. I. Solvent Blue-1, 2, 11, 35, 40, 44, 67, 70
C. I. Solvent Green-3
C. I. Solvent Black-3, 7, 22, 27, 29, 34, 43, 70
C. I. Disperse Yellow-5, 42, 54, 64, 79, 82, 93, 99, 100, 119, 122, 124, 126, 160, 184: 1, 186, 198, 199, 204, 224, 237
C. I. Disperse Orange-13, 29, 31: 1, 33, 49, 54, 55, 66, 73, 118, 119, 163
C. I. Disperse Red-54, 60, 72, 73, 86, 88, 91, 92, 93, 111, 126, 127, 134, 143, 145, 152, 153, 154, 159, 164, 167: 1, 177, 181 , 204,206,207,221,239,240,258,277,278,283,311,323,343,348,356,362
C. I. Disperse Violet-33
C. I. Disperse Blue-56, 60, 73, 87, 113, 128, 143, 148, 154, 158, 165, 165: 1, 165: 2, 176, 183, 185, 197, 198, 201, 214, 224, 225 257, 266, 267, 287, 354, 358, 365, 368
C. I. Disperse Green-6: 1, 9
In addition, Orient Chemical Industries Valifast Yellow 4120 Co., Ltd., Valifast Yellow 3150, Valifast Yellow 3108, Valifast Yellow 2310N, Valifast Yellow1101, Valifast Red 3320, Valifast Red 3304, Valifast Red 1306, Valifast Blue 2610, Valifast Blue 2606, Valifast Blue 1603, Oil Yellow GG-S, Oil Yellow 3G, Oil Yellow 129, Oil Yellow 107, Oil Yellow 105, Oil Scarlet 308, Oil Red RR, Oil Red OG, Oil Red 5B, O l Pink 312, Oil Blue BOS, Oil Blue 613, Oil Blue 2N, Oil Black BY, Oil Black BS, Oil Black 860, Oil Black 5970, Oil Black 5906, Oil Black 5905 Y -G, Kayset Yellow K-CL, Kayase Yellow GN, Kayase Yellow A-G, Kayase Yellow 2G, Kayase Red SF-4G, Kayase Red K-BL, Kayset Red A-BR, Kayet Red A-BR, Kayset Red A-BR, Kayset Red A-BR FS Yellow 1015, FS Ma manufactured by Arimoto Chemical Industry Co., Ltd. enta 1404, FS Cyan 1522, FS Blue 1504 and the like can also be used.

  The dye concentration is preferably 1% by mass to 15% by mass with respect to the entire composition.

  In the actinic ray curable composition of the present invention, various additives other than those described above can be used. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, rubber resins, and waxes can be added. In addition, any known basic compound can be used for the purpose of improving storage stability. Typical examples include basic organic compounds such as basic alkali metal compounds, basic alkaline earth metal compounds, and amines. Etc. It is also possible to combine a radically polymerizable monomer and an initiator into a radical / cation hybrid type curable ink.

  Basic compounds can also be added. By containing the basic compound, not only the ejection stability becomes good, but also the generation of wrinkles due to curing shrinkage is suppressed even under low humidity. As the basic compound, any known compounds can be used, and typical examples include basic alkali metal compounds, basic alkaline earth metal compounds, and basic organic compounds such as amines.

  Examples of the basic alkali metal compound include alkali metal hydroxides (lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.), alkali metal carbonates (lithium carbonate, sodium carbonate, potassium carbonate, etc.), alkali metals. Alcoholate (sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, etc.).

  Examples of the basic alkaline earth metal compound include alkaline earth metal hydroxides (magnesium hydroxide, calcium hydroxide, etc.), alkali metal carbonates (magnesium carbonate, calcium carbonate, etc.), and alkali metals. Alcoholate (magnesium methoxide, etc.).

  Examples of the basic organic compound include amines and nitrogen-containing heterocyclic compounds such as quinoline and quinolidine. Among these, amines are preferable from the viewpoint of compatibility with the photopolymerization monomer, for example, octylamine, naphthylamine, Xylenediamine, dibenzylamine, diphenylamine, dibutylamine, dioctylamine, dimethylaniline, quinuclidine, tributylamine, trioctylamine, tetramethylethylenediamine, tetramethyl-1,6-hexamethylenediamine, hexamethylenetetramine and triethanolamine, etc. Is mentioned.

  The concentration when the basic compound is present is preferably in the range of 10 to 1000 ppm by mass, particularly 20 to 500 ppm by mass relative to the total amount of the photopolymerizable monomer. In addition, a basic compound may be used individually or may be used in combination of multiple.

  Any known photoacid generator can be used in the actinic ray curable composition of the present invention.

  As the photoacid generator, for example, a chemically amplified photoresist or a compound used for photocationic polymerization is used (edited by Organic Electronics Materials Research Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), 187. To page 192). Examples of compounds suitable for the present invention are listed below.

First, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ salt of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, phosphonium, etc. be able to.

  Specific examples of onium compounds that can be used in the present invention are shown below.

  Secondly, sulfonated substances that generate sulfonic acid can be mentioned, and specific compounds thereof are exemplified below.

  Thirdly, halides that generate hydrogen halide can also be used, and specific compounds thereof are exemplified below.

  Fourthly, an iron allene complex can be mentioned.

  As a recording material that can be used in the present invention, in addition to ordinary uncoated paper, coated paper, etc., various non-absorbable plastics and films used for so-called soft packaging can be used. Examples thereof include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film. As other plastics, polycarbonate, acrylic resin, ABS, polyacetal, PVA, rubbers and the like can be used. Moreover, it is applicable also to metals and glass.

  The surface energies of these various plastic films differ greatly, and it has been a problem in the past that the dot diameter after ink landing varies depending on the recording material. With the configuration of the present invention, a good high-definition image can be formed on a wide range of recording materials having a surface energy of 35 to 60 mN / m, including OPP films having a low surface energy, OPS films, and PET having a relatively large surface energy. .

  In the present invention, it is more advantageous to use a long (web) recording material in terms of the cost of the recording material such as packaging cost and production cost, the production efficiency of the print, and the ability to cope with printing of various sizes. is there.

  Next, the image forming method of the present invention will be described.

  In the image forming method of the present invention, a method in which the above-mentioned actinic ray curable composition is ejected and drawn on a recording material by an ink jet recording method and then irradiated with actinic rays such as ultraviolet rays to cure the ink is preferable.

(Total ink film thickness after ink landing)
In the present invention, the total ink film thickness after the ink has landed on the recording material and cured by irradiation with actinic rays is preferably 2 to 25 μm. In the actinic ray curable ink jet recording in the screen printing field, the total ink film thickness currently exceeds 25 μm, but in the flexible packaging printing field where the recording material is often a thin plastic material, the recording material described above is used. In addition to the problem of curling and wrinkles, there is a problem in that the entire printed material is changed in its strain and texture.

  Here, “total ink film thickness” means the maximum value of the film thickness of the ink drawn on the recording material, and even for a single color, other two colors are superimposed (secondary color), three colors are superimposed, four colors are used. Even when recording is performed by the overlapping (white ink base) inkjet recording method, the meaning of the total ink film thickness is the same.

(Ink ejection conditions)
As the ink ejection conditions, it is preferable from the viewpoint of ejection stability that the recording head and ink are heated to 35 to 100 ° C. and ejected. The actinic ray curable composition has a large viscosity fluctuation range due to temperature fluctuations, and the viscosity fluctuations directly affect the droplet size and droplet ejection speed, causing image quality degradation. It is necessary to keep. The control range of the ink temperature is set temperature ± 5 ° C., preferably set temperature ± 2 ° C., more preferably set temperature ± 1 ° C.

  Moreover, in this invention, it is preferable that the amount of droplets discharged from each nozzle is 2 to 20 pl. Originally, in order to form a high-definition image, it is necessary for the amount of droplets to be within this range, but when discharging with this amount of droplets, the above-described discharge stability becomes particularly severe. According to the present invention, even when ejection is performed with a small droplet amount such as 2 to 20 pl, the ejection stability is improved and a high-definition image can be stably formed.

(Light irradiation conditions after ink landing)
In the image forming method of the present invention, the active light is preferably irradiated for 0.001 second to 1 second after the ink landing, more preferably 0.001 second to 0.5. Seconds. In order to form a high-definition image, it is particularly important that the irradiation timing is as early as possible.

  As a method for irradiating actinic rays, the basic method is disclosed in JP-A-60-132767. According to this, the light source is provided on both sides of the head unit, and the head and the light source are scanned by the shuttle method. Irradiation is performed after a certain period of time after ink landing. Further, the curing is completed by another light source that is not driven. In US Pat. No. 6,145,979, as an irradiation method, a method using an optical fiber or a method of irradiating a recording unit with UV light by applying a collimated light source to a mirror surface provided on the side surface of the head unit is disclosed. Has been. Any of these irradiation methods can be used in the image forming method of the present invention.

  In addition, there is a method of irradiating actinic rays in two stages, first irradiating actinic rays by the above-mentioned method within 0.001 to 2 seconds after ink landing, and further irradiating actinic rays after all printing is completed. This is one of the preferred embodiments. By dividing the irradiation of actinic rays into two stages, it is possible to further suppress the shrinkage of the recording material that occurs during ink curing.

  Conventionally, in the UV ink jet system, a light source with high illuminance in which the total power consumption of the light source exceeds 1 kW · hr is usually used in order to suppress dot spreading and bleeding after ink landing. However, when these light sources are used, particularly in printing on a shrink label or the like, the shrinkage of the recording material is so large that it cannot be used practically.

  In the present invention, it is preferable to use an actinic ray having the highest illuminance in the wavelength region of 254 nm, and even if a light source having a total power consumption of 1 kW · hr or more is used, a high-definition image can be formed and the recording material can be shrunk. Within practically acceptable level.

  In the present invention, it is preferable that the total power consumption of the light source for irradiating actinic rays is less than 1 kW · hr. Examples of the light source having a total power consumption of less than 1 kW · hr include, but are not limited to, a fluorescent tube, a cold cathode tube, a hot cathode tube, and an LED.

  Next, an ink jet recording apparatus (hereinafter simply referred to as a recording apparatus) of the present invention will be described.

  The recording apparatus of the present invention will be described below with reference to the drawings as appropriate. Note that the recording apparatus of the drawings is merely one aspect of the recording apparatus of the present invention, and the recording apparatus of the present invention is not limited to this drawing.

  FIG. 1 is a front view showing the configuration of the main part of the recording apparatus of the present invention. The recording apparatus 1 includes a head carriage 2, a recording head 3, an irradiation unit 4, a platen unit 5, and the like. In the recording apparatus 1, the platen unit 5 is installed under the recording material P. The platen unit 5 has a function of absorbing ultraviolet rays, and absorbs excess ultraviolet rays that have passed through the recording material P. As a result, a high-definition image can be reproduced very stably.

  The recording material P is guided by the guide member 6 and moves from the near side to the far side in FIG. 1 by the operation of the conveying means (not shown). A head scanning unit (not shown) scans the recording head 3 held by the head carriage 2 by reciprocating the head carriage 2 in the Y direction in FIG.

  The head carriage 2 is installed on the upper side of the recording material P, and stores a plurality of recording heads 3 to be described later according to the number of colors used for image printing on the recording material P, with the discharge ports arranged on the lower side. The head carriage 2 is installed with respect to the main body of the recording apparatus 1 in such a manner that it can reciprocate in the Y direction in FIG. 1, and reciprocates in the Y direction in FIG. 1 by driving the head scanning means.

  In FIG. 1, the head carriage 2 is illustrated as accommodating the recording heads 3 of yellow (Y), magenta (M), cyan (C), and black (K). The number of colors of the recording head 3 housed in the head carriage 2 can be determined as appropriate.

  The recording head 3 has a discharge port by operating a discharge means (not shown) provided with a plurality of actinic ray curable inks (for example, UV curable ink) supplied by an ink supply means (not shown). To the recording material P. The UV ink ejected by the recording head 3 is composed of a coloring material, a polymerizable monomer, an initiator, and the like, and the monomer crosslinks when the initiator acts as a catalyst when irradiated with ultraviolet rays. It has the property of being cured by a polymerization reaction.

  During the scanning in which the recording head 3 moves from one end of the recording material P to the other end of the recording material P in the Y direction in FIG. 1 by driving the head scanning means, a certain area (landing possible area) in the recording material P On the other hand, UV ink is ejected as ink droplets, and ink droplets are landed on the landable area.

  The above scanning is performed as many times as necessary, and after UV ink is ejected toward one landable area, the recording material P is appropriately moved from the front to the back in FIG. 1, the recording head 3 discharges UV ink to the next landable area adjacent in the depth direction in FIG.

  By repeating the above operation and ejecting the UV ink from the recording head 3 in conjunction with the head scanning means and the conveying means, an image composed of an aggregate of UV ink droplets is formed on the recording material P.

  The irradiation unit 4 includes an ultraviolet lamp that emits ultraviolet light in a specific wavelength region with stable exposure energy and a filter that transmits ultraviolet light of a specific wavelength. Here, as the ultraviolet lamp, a mercury lamp, a metal halide lamp, an excimer laser, an ultraviolet laser, a cold cathode tube, a hot cathode tube, a black light, an LED (light emitting diode) and the like can be applied. A cathode tube, a hot cathode tube, a mercury lamp or black light is preferred. In particular, a low-pressure mercury lamp, a hot cathode tube, a cold cathode tube, and a germicidal lamp that emit ultraviolet light having a wavelength of 254 nm are preferable because they can effectively prevent bleeding and control the dot diameter. By using black light as the radiation source of the irradiation means 4, the irradiation means 4 for curing the UV ink can be produced at low cost.

  The irradiating means 4 has substantially the same shape as the maximum one that can be set by the recording apparatus (UV inkjet printer) 1 among the landable areas in which the recording head 3 ejects UV ink by one scan driven by the head scanning means. , Having a shape larger than the landable area.

  The irradiation means 4 is fixed on both sides of the head carriage 2 so as to be substantially parallel to the recording material P.

  As described above, as a means for adjusting the illuminance of the ink discharge portion, not only the entire recording head 3 is shielded, but in addition, the ink discharge of the recording head 3 is determined from the distance h1 between the irradiation means 4 and the recording material P. It is effective to increase the distance h2 between the portion 31 and the recording material P (h1 <h2), or to increase the distance d between the recording head 3 and the irradiation means 4 (d is increased). Further, it is more preferable to provide a bellows structure 7 between the recording head 3 and the irradiation means 4.

  Here, the wavelength of the ultraviolet rays irradiated by the irradiation means 4 can be changed as appropriate by replacing the ultraviolet lamp or filter provided in the irradiation means 4.

  The ink of the present invention has excellent ejection stability and is particularly effective when an image is formed using a line head type recording apparatus.

  FIG. 2 is a top view illustrating another example of the configuration of the main part of the ink jet recording apparatus.

  The ink jet recording apparatus shown in FIG. 2 is called a line head system, and a plurality of ink jet recording heads 3 of each color are fixedly arranged on the head carriage 2 so as to cover the entire width of the recording material P. ing.

  On the other hand, on the downstream side of the head carriage 2, there is provided irradiation means 4 arranged so as to cover the entire width of the recording material P and cover the entire area of the ink printing surface. As the ultraviolet lamp used in the illuminating means 4, the same one as described in FIG. 1 can be used.

  In this line head system, the head carriage 2 and the irradiating means 4 are fixed, and only the recording material P is conveyed, and ink ejection and curing are performed to form an image.

  Examples of the present invention will be specifically described below, but the embodiments of the present invention are not limited to these examples.

Example 1
<Preparation of pigment dispersion D-1>
The following compounds were placed in a stainless beaker and dissolved by stirring for 1 hour while heating on a 65 ° C hot plate.

PB822 (dispersant manufactured by Ajinomoto Fine Techno Co., Ltd.) 6 parts OXT221 (Oxetane compound manufactured by Toa Gosei Co., Ltd.) 74 parts After cooling to room temperature, the following amount of pigment is added to this and placed in a glass bottle with 200 g of zirconia beads having a diameter of 1 mm and sealed tightly Then, after a dispersion treatment for 2 hours with a paint shaker, the zirconia beads were removed to obtain a pigment dispersion D-1.

C. I. Pigment Blue 15: 4 20 parts <Preparation of pigment dispersion D-2>
The following compounds were placed in a stainless beaker and dissolved by stirring for 1 hour while heating on a 65 ° C hot plate.

PB822 (dispersant manufactured by Ajinomoto Fine-Techno Co., Ltd.) 6 parts OXT211 (Oxetane compound manufactured by Toa Gosei Co., Ltd.) 74 parts After cooling to room temperature, the following amount of pigment is added to this and placed in a glass bottle with 200 g of zirconia beads having a diameter of 1 mm and sealed tightly Then, after dispersing for 4 hours with a paint shaker, the zirconia beads were removed to obtain a pigment dispersion D-2.

C. I. Pigment Black 7 20 parts <Preparation of ink composition>
An ink composition having the composition shown in Table 1 was prepared by filtration through a 1.0 μm membrane filter.

  The structures of the compounds described in Table 1 are as follows. Moreover, each composition viscosity is 30-41 mPa * s.

(Curability evaluation)
Each ink was applied to PET: polyethylene terephthalate so as to have a thickness of about 5 μm, and then irradiated with a low-pressure mercury lamp at an illuminance of 80 mW / cm ² (UVPF-A1 (manufactured by Iwasaki Electric Co., Ltd.) and 254 nm illuminance) for 30 seconds. The curability was evaluated by touching with a finger after irradiation.

◎: There is no stickiness ○: Slight stickiness is felt △: There is stickiness, but it cannot be removed by rubbing ×: It does not cure and flows

  From Table 2, it can be seen that the actinic ray curable composition of the present invention is excellent in curability.

Example 2
<Preparation of pigment dispersion D-3>
The following compounds were placed in a stainless beaker and dissolved by stirring for 1 hour while heating on a 65 ° C hot plate.

PB822 (dispersant manufactured by Ajinomoto Fine Techno Co., Ltd.) 6 parts OXT221 (Oxetane compound manufactured by Toa Gosei Co., Ltd.) 74 parts After cooling to room temperature, the following amount of pigment is added to this and placed in a glass bottle with 200 g of zirconia beads having a diameter of 1 mm and sealed tightly Then, after being dispersed for 2 hours with a paint shaker, the zirconia beads were removed to obtain a pigment dispersion D-3.

C. I. Pigment Red 57: 1 20 parts <Preparation of pigment dispersion D-4>
The following compounds were placed in a stainless beaker and dissolved by stirring for 1 hour while heating on a 65 ° C hot plate.

PB822 (Ajinomoto Fine Techno Co., Ltd.) 6 parts OXT101 (Toa Gosei Oxetane compound) 74 parts After cooling to room temperature, add the following amount of pigment to this, put it in a glass bottle with 200 g of zirconia beads with a diameter of 1 mm, and paint After dispersing for 4 hours with a shaker, the zirconia beads were removed to obtain a pigment dispersion D-4.

C. I. Pigment Yellow 13 20 parts <Preparation of pigment dispersion D-5>
The following compounds were placed in a stainless beaker and dissolved by stirring for 1 hour while heating on a 65 ° C hot plate.

PB822 (dispersant manufactured by Ajinomoto Fine Techno Co., Ltd.) 6 parts OXT211 (Oxetane compound manufactured by Toa Gosei Co., Ltd.) 74 parts After cooling to room temperature, the following amount of pigment is added to this and placed in a glass bottle with 200 g of zirconia beads having a diameter of 1 mm. Sealed and dispersed for 2 hours in a paint shaker, and then the zirconia beads were removed to obtain a pigment dispersion D-5.

C. I. 20 parts of Pigment Yellow 138 <Preparation of Pigment Dispersion Liquid D-6>
The following compounds were placed in a stainless beaker and dissolved by stirring for 1 hour while heating on a 65 ° C hot plate.

PB822 (dispersant manufactured by Ajinomoto Fine-Techno Co., Ltd.) 6 parts OXT211 (Oxetane compound manufactured by Toa Gosei Co., Ltd.) 74 parts After cooling to room temperature, the following amount of pigment is added to this and placed in a glass bottle with 200 g of zirconia beads having a diameter of 1 mm and sealed tightly Then, after dispersing for 4 hours with a paint shaker, the zirconia beads were removed to obtain dispersion D-6.

C. I. Pigment Violet 19 20 parts <Preparation of pigment dispersion D-7>
The following compounds were placed in a stainless beaker and dissolved by stirring for 1 hour while heating on a 65 ° C hot plate.

PB822 (dispersant manufactured by Ajinomoto Fine-Techno Co., Ltd.) 6 parts OXT211 (Oxetane compound manufactured by Toa Gosei Co., Ltd.) 74 parts After cooling to room temperature, the following amount of pigment is added to this and placed in a glass bottle with 200 g of zirconia beads having a diameter of 1 mm and sealed tightly Then, after being dispersed for 2 hours in a paint shaker, the zirconia beads were removed to obtain a pigment dispersion D-7.

C. I. Pigment Blue 15: 4 20 parts <Preparation of Pigment Dispersion Liquid D-8>
The following compounds were placed in a stainless beaker and dissolved by stirring for 1 hour while heating on a 65 ° C hot plate.

PB821 (manufactured by Ajinomoto Fine Techno Co., Ltd.) 6 parts OXT221 (Oxetane compound produced by Toa Gosei Co., Ltd.) 74 parts After cooling to room temperature, add the following amount of pigment to this and put it in a glass bottle with 200 g of zirconia beads having a diameter of 1 mm, After dispersing for 4 hours with a paint shaker, the zirconia beads were removed to obtain a pigment dispersion D-8.

C. I. Pigment Black 7 20 parts << Preparation of ink composition set >>
Ink composition sets 1 to 8 were prepared by filtering with a 1.0 μm membrane filter with the compositions shown in Tables 3 to 10 to prevent clogging of the printer.

  The viscosity of each ink composition set prepared above is as follows. The viscosity is indicated by the viscosity range at the maximum and minimum viscosity of each color ink.

Ink composition set 1: 20-30 mPa · s
Ink composition set 2: 20 to 30 mPa · s
Ink composition set 3: 20 to 30 mPa · s
Ink composition set 4: 20 to 30 mPa · s
Ink composition set 5: 25 to 34 mPa · s
Ink composition set 6: 25 to 34 mPa · s
Ink composition set 7: 25 to 34 mPa · s
Ink composition set 8: 25 to 34 mPa · s

  Details of the structure and display of the compounds in the table are as follows.

K: Dark black ink C: Dark cyan ink M: Dark magenta ink Y: Dark yellow ink LC: Light cyan ink LM: Light magenta ink [Inkjet image forming method]
1 to 4 are loaded into an ink jet recording apparatus having the configuration shown in FIG. 1 having a piezo type ink jet nozzle, and a long length of 600 mm and a length of 500 m shown in Table 11 is loaded. The following image recording was continuously performed on each recording material. The ink supply system was composed of an ink tank, a supply pipe, a front chamber ink tank immediately before the head, a pipe with a filter, and a piezo head. The ink was insulated from the front chamber tank to the head portion and heated at 50 ° C. The piezo head was driven so that 2 to 20 pl multi-sized dots could be ejected at a resolution of 720 × 720 dpi (dpi represents the number of dots per inch, that is, 2.54 cm), and each ink was ejected continuously. After landing, it is cured instantaneously (less than 0.5 seconds after landing) by the lamp units on both sides of the carriage. After recording, the total ink film thickness was measured and found to be in the range of 2.3 to 13 μm. The inkjet image was formed in an environment of 25 ° C. and 30% RH according to the above method.

  Further, in the same manner, an image was formed using the ink composition sets 5 to 8 using the line head recording type ink jet recording apparatus shown in FIG.

  The details of the abbreviations of the recording materials listed in Table 11 are as follows.

OPP: oriented polypropylene
PET: Polyethylene terephthalate
PVC: polyvinyl Chloride

<Evaluation of inkjet recording image>
Each image recorded by the above image forming method was subjected to the following evaluations.

(Mixed colors)
At 720 dpi, printing was performed so that 1 dot of each color of Y, M, C, and K was adjacent to each other, each adjacent color dot was enlarged with a loupe, the degree of bleeding was visually observed, and color mixing was evaluated according to the following criteria.

◎: Adjacent dot shape keeps perfect circle and no blur ○: Adjacent dot shape keeps almost perfect circle and almost no blur △: Adjacent dot is slightly blurred and dot shape is slightly displaced X: Adjacent dots are blurred and mixed. Table 12 shows the evaluation results obtained as described above.

  From Table 12, it can be seen that the image forming method having the configuration according to the present invention can record a high-definition image without color mixing (bleeding) as compared with the comparison.

It is a front view which shows an example of a structure of the principal part of the inkjet recording device of this invention. It is a top view which shows another example of a structure of the principal part of the inkjet recording device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Head carriage 3 Inkjet recording head 31 Ink ejection port 4 Irradiation means 5 Platen part 6 Guide member 7 Bellows structure P Recording material

Claims (10)

A compound having an oxetane ring as a photopolymerizable compound, a compound having an epoxy group represented by the general formula (1), and 0.1 to 10% by mass in general with respect to the total mass of the actinic ray curable composition An actinic ray curable composition containing a diol structure represented by formula (2).

(R ₁ represents an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted aromatic group, or an acyl group.)

(R ₂ represents an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted aromatic group, or an acyl group.) The compound having a diol structure represented by the general formula (2) is a compound obtained by ring opening of a compound having an epoxy group represented by the general formula (1). Actinic ray curable composition. The actinic ray curable composition according to claim 1 or 2, which contains a pigment. The actinic ray curable composition according to claim 1, comprising an oil-soluble dye. The actinic ray curable composition according to any one of claims 1 to 4, wherein the viscosity at 25 ° C is 7 to 50 mPa · s. An actinic ray curable composition according to any one of claims 1 to 5 is jetted onto a recording material from an ink jet recording head and printing is performed on the recording material. An image forming method comprising irradiating actinic rays for 0.001 to 1 second after landing of a mold composition. An actinic ray curable composition according to any one of claims 1 to 5 is jetted onto a recording material from an ink jet recording head and printing is performed on the recording material. An image forming method, wherein the total film thickness after landing of the mold composition and curing by irradiation with actinic rays is 2 to 25 μm. An image forming method in which the actinic ray curable composition according to any one of claims 1 to 5 is jetted onto a recording material from an ink jet recording head, and printing is performed on the recording material, the ink jet recording head An image forming method, wherein the amount of droplets of the actinic ray curable composition discharged from each nozzle is 2 to 20 pl. An image forming method in which the actinic ray curable composition according to any one of claims 1 to 5 is jetted onto a recording material from an ink jet recording head, and printing is performed on the recording material. An image forming method comprising forming an image by ejecting from a recording head. It is an inkjet recording device used for the image forming method of any one of Claims 6-9, Comprising: It discharges, after heating actinic-light curable composition and a recording head to 35 to 100 degreeC. An inkjet recording apparatus.

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