JP2003292837A - Inkjet ink, image formation process, and finished printed matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording image formation process which can reproduce a highly fine image on any recording material without curling the recording material, to provide an inkjet ink used therefor, and to provide a finished printed matter. <P>SOLUTION: The inkjet ink is one which is cured with an actinic radiation and is substantially solvent-free and contains a water reprellent. In desirable embodiments, the surface tension of the ink is 3×10<SP>-4</SP>-5×10<SP>-4</SP>N/cm, the viscosity at 25°C is 35-200 mPas, or a combination of at least one of each of a photopolymerizable monofunctional monomer or its oligomer and a polyfunctional photopolymerizable monomer having two or more functional groups or its oligomer is used. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method by an inkjet recording system capable of reproducing a high-definition image on any recording material, an inkjet ink used therefor, and a final printed matter.

[0002]

2. Description of the Related Art In recent years, the ink jet recording method has been applied to various printing fields such as photography, various printings, markings, special printings such as color filters, because an image can be produced easily and inexpensively. In particular, a recording device that emits and controls fine dots, ink that has improved color reproduction range, durability, and emission suitability, and special paper that has dramatically improved ink absorbency, coloring material coloring, surface gloss, etc. It is also possible to obtain an image quality comparable to that of a silver halide photograph by using. The improvement in image quality of today's inkjet recording system is achieved only when all of the recording device, ink, and special paper are prepared.

However, the ink jet system requiring special paper has problems that the recording material is limited and the cost of the recording material is increased. Therefore, many attempts have been made to record on a transfer medium different from dedicated paper by an inkjet method. Specifically, there are a phase change inkjet method using a solid wax ink at room temperature, a solvent inkjet method using an ink mainly composed of a quick-drying organic solvent, and a UV inkjet method of crosslinking by UV light after recording. . Among them, the UV inkjet method has been attracting attention in recent years because it has a relatively low odor as compared with the solvent-based inkjet method and can perform recording on a recording material that does not dry quickly and does not absorb ink. Japanese Patent Publication No. 5-54667, Japanese Patent Application Laid-Open No. 6-200204, and Japanese Patent Publication No. 2000-504778 disclose UV-curable inkjet inks.

However, even if these inks are used, the dot diameter after landing changes greatly depending on the type of recording material and the working environment, and high-definition images can be formed on all recording materials. Was impossible. Further, due to the above factors, not only the image quality but also the problem that the recording material curls due to ink contraction. In particular, in thin film plastic films used in flexible packaging such as food packaging and adhesive labels, the surface energy often changes greatly depending on the recording material, and the dot diameter changes completely due to the large change in ink wettability. In addition, the way the ink shrinks greatly changes, and the recording material curls.

Among conventional UV-curable ink jet inks, those which do not substantially contain a solvent such as water and organic solvents are suitable for recording materials having high surface energy and low surface tension of photopolymerizable monomers. It was difficult to form a perfect image.

Due to the above problems, the UV ink jet system has not been put to practical use for flexible packaging printing or label printing.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming method by inkjet recording capable of reproducing a high-definition image on any recording material without curling the recording material, and an inkjet used therefor. Ink for ink and final printed matter are provided.

[0008]

The object of the present invention is achieved by the following constitutions.

1) An ink which is curable by actinic rays and which contains substantially no solvent and contains a water repellent.

2) Surface tension of 3 × 10 ^{-4 to} 5 × 10 ^-4 N
/ Cm, the inkjet ink according to 1).

3) Viscosity at 25 ° C. is 35 to 200 m
The inkjet ink according to 1) or 2), which is Pa · s.

4) One or more photopolymerizable monofunctional monomers or oligomers and two or more polyfunctional photopolymerizable monomers or oligomers are used in combination 1), 2) or 3).
The inkjet ink described.

5) Using the ink according to any one of 1) to 4), a recording head having at least one nozzle capable of selectively controlling ejection of ink droplets is used. An image forming method of heating to 100 ° C. and ejecting.

6) A final printed matter on which an image is formed by the image forming method described in 5) and the recording material is a plastic film.

7) A final printed matter on which an image is formed by the image forming method described in 5) and the recording material is a shrink film.

8) A final printed material on which an image is formed by the image forming method described in 5) and the recording material is an adhesive label.

The present invention will be described in detail below. The inkjet recording ink used in the present invention (hereinafter also abbreviated as the ink of the present invention) is composed of at least a polymerizable monomer, a photopolymerization initiator, and a water repellent.

In order to improve the adhesion to the recording material, it is effective to add a very small amount of an organic solvent, but the ink of the present invention is a solvent-free solvent that does not substantially contain a solvent such as water or an organic solvent. It is ink. The term “substantially free from” means that the amount added is 0.1 to 3 mass%. If the content of the solvent exceeds 3%, the ink is dried and adhered to the surface of the ink ejection nozzle due to the evaporation of the solvent, which hinders stable ejection.

The water repellent contained in the ink of the present invention has water repellency, and is safe and colorless and transparent.
It is preferable to use one that does not affect the color of the ink. For example, a silane coupling agent having a trifluoromethyl (CF ₃ ) group and an alkoxy group at the end, silicone oil, fluororesin, paraffin wax, silicone oil and acrylic. Examples thereof include a mixture with a resin.

CF at the end₃Group having an alkoxy group and an alkoxy group
CF as the run coupling agent₃(CF₂)₃CH₂C
H₂Si (OCH₃)₃, CF₃(CF₂)_FiveCH₂CH₂Si
(OCH₃)₃, CF₃(CF₂)₇CH₂CH₂Si (OC
H₃)₃, CF₃(CF₂)₉CH ₂CH₂Si (OC
H₃)₃, (CF₃)₂CF (CF₂)_FourCH₂CH₂Si (O
CH₃)₃, (CF₃)₂CF (CF₂)₆CH₂CH₂Si
(OCH₃)₃, (CF₃)₂CF (CF₂)₈CH₂CH₂S
i (OCH₃)₃, CF₃(C₆H_Four) C₂H_FourSi (OC
H₃)₃, CF₃(CF₂)₃(C₆H_Four) C₂H_FourSi (OC
H₃)₃, CF₃(CF₂)_Five(C₆H_Four) C₂H_FourSi (OC
H₃)₃, CF₃(CF₂)₇(C₆H_Four) C₂H_FourSi (OC
H₃)₃, CF₃(CF₂)₃CH₂CH₂SiCH₃(OCH
₃)₂, CF₃(CF₂) _FiveCH₂CH₂SiCH₃(OC
H₃)₂, CF₃(CF₂)₇CH₂CH₂SiCH₃(OCH
₃)₂, CF₃(C_F2)₉CH₂CH₂SiCH₃(OCH₃)
₂, (CF₃)₂CF (CF₂)_FourCH₂CH₂SiCH₃(O
CH₃)₂, (CF₃)₂CF (CF₂)₆CH₂CH₂SiC
H₃(OCH₃)₂, (CF₃)₂CF (CF₂)₈CH₂CH
₂SiCH₃(OCH₃)₂, CF₃(C₆H_Four) C₂H_FourSi
CH₃(OCH₃)₂, CF₃(CF₂) ₃(C₆H_Four) C₂H_Four
SiCH₃(OCH₃)₂, CF₃(CF₂)_Five(C₆H_Four) C
₂H_FourSiCH₃(OCH₃)₂, CF₃(CF₂)₇(C
₆H_Four) C₂H_FourSiCH₃(OCH₃)₂, CF₃(CF₂)₃
CH₂CH₂Si (OC₂H_Five)₃, CF₃(CF₂)_FiveCH₂
CH₂Si (OC₂H_Five)₃, CF₃(CF₂)₇CH₂CH₂
Si (OC₂H_Five)₃, CF₃(CF₂)₉CH₂CH₂Si
(OC₂H_Five)₃, CF₃CH₂CH₂Si (OCH₃)₃Etc.
Can be used.

In the case of a solventless ink containing substantially no solvent, the surface tension of the monomer and / or oligomer itself is low, and a high-definition image is formed on a recording material having a large surface energy such as PET (polyethylene terephthalate). It was difficult.

The surface tension of the ink is preferably 3 × 10.
^{-4 to} 5 × 10 ^-4 N / cm, more preferably 3 × 10 ^-4 to
It is 4.5 × 10 ⁻⁴ N / cm. If the surface tension is too low, the spread of dots on the recording material with a large surface energy will be large, and if the surface tension is too high, the dots will not spread on a recording material with a small surface energy. It becomes difficult to form a high-definition image on any recording material.

In the present invention, it is preferable to use an ink having a viscosity at 25 ° C. of 35 to 200 mPa · s. By using such an ink, it becomes easy to keep the dot diameter of the landed ink constant, and the image quality is improved.

In consideration of the injection property, the injection temperature is preferably 7 to 30 mPa · s, more preferably 7 to 20 mPa · s.
The composition ratio is determined so as to be mPa · s.

As described above, the ink which can be stably ejected and does not substantially contain a solvent is heated at the time of ejection to lower the viscosity of the ink to be ejected stably, and when the temperature is lowered after landing on the recording material, the ink viscosity is reduced. By using a water repellent agent for the rising ink, it is possible to more stably form a high-definition image on any recording material.

Various (meth) acrylate monomers can be used as the polymerizable monomer. For example, i-amyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate,
i-myrstil acrylate, i-stearyl acrylate, 2-ethylhexyl diglycol acrylate,
2-hydroxybutyl acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl Acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-
Acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl-
Monofunctional monomers such as 2-hydroxyethyl-phthalic acid, lactone-modified flexible acrylate, t-butylcyclohexyl acrylate; triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene. Glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9
Nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate, EO (ethylene oxide) adduct of bisphenol A diacrylate, P of bisphenol A
Bifunctional monomers such as O (propylene oxide) adduct diacrylate, hydroxypivalic acid neopentyl glycol diacrylate, polytetramethylene glycol diacrylate; trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, Trifunctional or more than pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxy triacrylate, cowprolactone modified trimethylolpropane triacrylate, pentaerythritol ethoxy tetraacrylate, caprolactam modified dipentaerythritol hexaacrylate, etc. The polyfunctional monomer of is mentioned.

Besides, polymerizable oligomers can be blended in the same manner as the monomers. Examples of the polymerizable oligomer include epoxy acrylate, aliphatic urethane acrylate, aromatic urethane acrylate, polyester acrylate, and linear acrylic oligomer.

In the present invention, it is particularly preferable to use a monofunctional, difunctional, trifunctional or higher polyfunctional monomer in combination as the polymerizable monomer. The monofunctional monomer has a large effect of lowering the shrinkage rate at the time of curing, and also has a low viscosity and easily obtains ejection stability during inkjet recording. The bifunctional monomer is preferably added because it has an appropriate sensitivity and excellent adhesion to various recording materials. A trifunctional or higher polyfunctional monomer can obtain sensitivity and film strength after curing. By using these three together, curling and waviness due to curing shrinkage can be prevented,
Adhesion to the recording material, followability, high sensitivity, and high image quality are achieved at the same time. In particular, it is very effective in the case of a shrink film that shrinks the recording material itself after printing.

As a mixing ratio of the above three, the monofunctional monomer is 5 to 40% by mass of the entire ink composition, the bifunctional monomer is 5 to 40% by mass, and the trifunctional or higher polyfunctional monomer is 5%.
It is preferable to contain -30 mass%.

The monomers used in combination have a difference in the solubility parameter (SP value) between the maximum value and the minimum value of 1 or more, and the combination prevents adhesion to various recording materials and curling due to curing shrinkage. It is preferable in terms. More preferably 1.5
That is all.

From the viewpoint of safety such as sensitization, skin irritation, eye irritation, mutagenicity and toxicity, among the above monomers, i-amyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate,
Decyl acrylate, i-myristyl acrylate, i
-Stearyl acrylate, ethoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, isobornyl acrylate, lactone modified flexible acrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, EO modified trimethylol Propane triacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxytriacrylate, caprolactone modified trimethylolpropane triacrylate, pentaerythritol ethoxytetraacrylate, caprolactam modified dipentaerythritol hexaacrylate It is preferred. Furthermore, among these, stearyl acrylate, lauryl acrylate, i-stearyl acrylate, ethoxydiethylene glycol acrylate, isobornyl acrylate, tetraethylene glycol diacrylate, EO-modified trimethylolpropane triacrylate, glycerin propoxytriacrylate, caprolactone-modified trimethylolpropane triacrylate. As the photopolymerization initiator (hereinafter, also simply referred to as an initiator) in which caprolactam-modified dipentaerythritol hexaacrylate is particularly preferable, arylalkylketone, oxime ketone, thiobenzoic acid-
S-phenyl, titanocene, aromatic ketone, thioxanthone, benzyl and quinone derivatives, ketocoumarins, etc.
Conventionally known initiators can be used. For the initiator,
Details on "Applications and markets of UV / EB curing technology" (CMC Publishing, supervised by Yoneho Tabata / edited by Radtech Study Group).
Among them, acyl phosphine oxide and acyl phosphonate have high sensitivity and their absorption is reduced by photocleavage of the initiator.
It is particularly effective for internal curing in an ink image having a thickness of μm.

Specifically, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide and the like are preferable.

Further, like the above-mentioned monomer, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, bis, and bis are selected in consideration of safety. (2,
6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2-hydroxy-2-
Methyl-1-phenylpropan-1-one (Darocur (R) 1173) and the like are preferably used. The preferable addition amount is 1 to 6% by mass, preferably 2% by mass of the whole ink composition.
Is about 5% by mass.

In the present invention, for the purpose of reproducing a high-definition image on any recording material, it is preferable to change the wavelength or the intensity to divide the irradiation into two stages, and the initiators are also two types having different absorption wavelengths. It is particularly preferable to use the above in combination.

When coloring the ink composition, a coloring material is added. As the coloring material, a coloring material that can be dissolved or dispersed in the main component of the polymerizable compound can be used, but a pigment is preferable from the viewpoint of weather resistance. The following pigments can be specifically used, but the pigments are not limited to these.

C. I. Pigment Yellow-
1, 3, 12, 13, 14, 17, 81, 83, 87,
95, 109, 42, C.I. I. Pigment Orange-16, 36,
38, C.I. I. Pigment Red-5, 22, 38, 4
8: 1, 48: 2, 48: 4, 49: 1, 53: 1, 5
7: 1, 63: 1, 144, 146, 185, 101, C.I. I. Pigment Violet-19, 23, C.I. I. Pigment Blue-15: 1, 15:
3,15: 4,18,60,27,29, C.I. I. Pigment Green-7, 36, C.I. I. Pigment White-6, 18, 2
1, C.I. I. Pigment Black-7, and it is preferable to use a white ink for the purpose of improving the color hiding property on a transparent substrate such as a plastic film.

For dispersing the pigment, a ball mill, a sand mill,
An attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, paint shaker, etc. can be used. It is also possible to add a dispersant when dispersing. A polymer dispersant is preferably used as the dispersant, and examples of the polymer dispersant include Solsperse series manufactured by Avecia. It is also possible to use synergists corresponding to various pigments as the dispersion aid. These dispersants and dispersion aids are pigment 1
It is preferable to add 1 to 50 parts by mass to 00 parts by mass.

The dispersion medium is a solvent or a polymerizable compound, but the radiation-curable ink used in the present invention is preferably solvent-free because it reacts and cures immediately after landing of the ink. If the solvent remains in the cured image, problems of solvent resistance deterioration and residual solvent VOC occur. Therefore, it is preferable in view of dispersion suitability that the dispersion medium is not a solvent but a polymerizable compound, among which a monomer having the lowest viscosity is selected.

The dispersion has an average particle size of 0.08 to 0.5 μm.
And the maximum particle size is 0.3 to 10 μm,
A pigment, a dispersant, so that the thickness is preferably 0.3 to 3 μm,
Selection of dispersion medium, dispersion conditions, and filtration conditions are set. By controlling the particle size, clogging of the head nozzle can be suppressed, and the storage stability of the ink, the transparency of the ink, and the curing sensitivity can be maintained.

The color material is preferably added in an amount of 1 to 10% by mass of the total ink. Next, other components added to the ink will be described.

A polymerization inhibitor may be added in an amount of 200 to 20000 ppm in order to improve the storage stability of the ink composition. Since it is preferable that the ultraviolet curable ink is heated and reduced in viscosity before being ejected, it is preferable to add a polymerization inhibitor in order to prevent head clogging due to thermal polymerization.

In addition to these, a surfactant, a leveling additive, a matting agent, a polyester resin for adjusting physical properties of the film, a polyurethane resin, a vinyl resin, if necessary.
Acrylic resins, rubber resins, and waxes can be added.

Further, due to the light shielding effect of the ink coloring material, as a means for preventing sensitivity, it is also possible to combine a cationically polymerizable monomer having a long initiator life with an initiator to form a radical / cation hybrid type curable ink. .

Next, the image forming method will be described. In the present invention, the ink composition is ejected and drawn on a recording material by an inkjet recording method, and then the ink is cured by irradiating with actinic rays such as ultraviolet rays. In terms of ejection stability, it is preferable to heat the head and the ink to 40 to 100 ° C. to reduce the ink viscosity and eject the ink. Since the actinic ray curable ink generally has a higher viscosity than the water-based ink, the fluctuation range of viscosity due to temperature fluctuation is large. Since the viscosity fluctuation directly affects the droplet size and the droplet ejection speed as they are, and the image quality deteriorates, it is necessary to keep the ink temperature as constant as possible. The ink temperature control range is set temperature ± 5 ° C, preferably set temperature ± 2
C., more preferably set temperature ± 1.degree.

An important process is the irradiation condition. The basic irradiation 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. The light irradiation is performed after a certain time has elapsed after the ink has landed. Further, 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 and a method of irradiating a recording section with UV light by applying a collimated light source to a mirror surface provided on the side surface of the head unit are disclosed.
In the present invention, any of these irradiation methods can be used.

Regarding the type of light source for irradiation, UV-
In addition to ultraviolet rays such as A, UV-B, and UV-C, vacuum ultraviolet rays, and visible light, γ rays and β rays can be used. Examples of ultraviolet rays include high pressure mercury lamps, metal halide lamps, low pressure mercury lamps, electrodeless UV lamps, UV lasers, xenon lamps, insect traps, cold cathode tubes, germicidal lamps, LEs.
D and the like can be used, but not limited thereto.
High-pressure mercury lamp, low-pressure mercury lamp, metal halide lamp, electrodeless UV lamp, UV
A laser, a xenon lamp or the like is used, and when a light amount is not required so much, an insect trap light, a cold cathode tube, a germicidal lamp, an LED or the like is used.

As the recording material, in addition to ordinary uncoated paper, coated paper and the like, various plastics and films thereof used for so-called soft packaging can be used. Examples of various plastic films include PET film, OPS (stretch-polystyrene) film, and OPP.
(Stretch-polypropylene) film, ONy (stretch-nylon) film, PVC (polyvinyl chloride) film, PE (polyethylene) film, TAC (cellulose triacetate) film and the like. Other plastics that can be used include PC (polycarbonate), acrylic resin, ABS (acrylic-butadiene-styrene), polyacetal, PVA (polyvinyl alcohol), and rubbers. Further, it is also applicable to metals and glasses.

Among these recording materials, in particular, PET film, OPS film, O, which can be shrunk by heat,
The configuration of the present invention is effective when forming an image on a PP film, an ONy film, a PVC film, or the like. In these base materials, not only the curling and deformation of the film are apt to occur due to the curing shrinkage of the ink and the heat generated during the curing reaction, but also the ink film is hard to follow the shrinkage of the base material. The present invention is also particularly effective in the case of forming an image on a pressure-sensitive adhesive label whose surface is coated with various kinds of substrates as described above.

It is more advantageous to use a long (web) recording material in terms of packaging cost, production cost, recording material cost, print production efficiency, and compatibility with various sizes of prints.

[0050]

The present invention will be described below with reference to examples, but the embodiments of the present invention are not limited thereto.

<Preparation of Ink> Comparative ink 1 having the composition shown in Table 1, ink 2 of the present invention, and more preferable inks 3 and 4 of the present invention were prepared. Each ink has five colors of K (black), C (cyan), M (magenta), Y (yellow), and W (white).

The average ink viscosity and average ink surface tension of each ink are as follows. Viscosity (mPa · s / 25 ° C., 70 ° C.) Surface tension (× 10 ⁻⁴ N / cm) Ink 1: 80,15 2.6 Ink 2: 80,15 3.2 Ink 3: 100, 15 3.5 Ink 4: 120,17 4.0 The above ink viscosity was measured by measuring the melt viscosity at 25 ° C. and 70 ° C. using a rotational viscometer (manufactured by Tokimec: EDL model), and the surface tension was measured using a platinum thin film plate.
The measurement was performed by the helmy method.

[0053]

[Table 1]

<Inkjet recording> The above inks 1 to 4
Using an inkjet recording apparatus equipped with a piezo type inkjet nozzle, the width 600 shown in Table 2 was used.
Printing recording was performed on various recording materials of mm. The ink supply system was composed of an ink tank, a supply pipe, an anterior chamber ink tank immediately before the head, a pipe with a filter, and a piezo head, and heat insulation and heating were performed from the anterior chamber tank to the head portion. Temperature sensors are installed near the nozzle of the antechamber tank and the piezo head, and the nozzle part is always 70 ° C ±
The temperature was controlled to be 2 ° C. 8 piezo heads
~ 30 pl (picoliter) multi-size dots 7
20 x 720 dpi (dpi is 1 inch = 2.54 cm
The number of dots per dot is shown), and the ink is driven and ejected at a resolution of. The irradiation conditions after landing were as shown in Tables 2-5.

<Character Quality> 6-point MS Mincho typeface characters were printed at the target densities of Y, M, C, and K colors, and the rubbing of the letters was magnified with a magnifying glass to evaluate them in four levels.

⊚: No rustiness: Slight rustiness is visible △: Roughness is visible, but it is a level at which it can be discerned as characters and can be used as close as possible; Level at which rustiness is severe and characters cannot be used faintly << Mixed color (bleeding) >> Adjacent color dots Was magnified with a loupe, and the degree of color bleeding was visually evaluated.

⊚: Adjacent dot shapes maintain a perfect circle and no blurring: Adjacent dot shapes maintain a nearly perfect circle, almost no blurring Δ: Adjacent dots slightly blurring and the dot shape is a little broken However, it is a level that can be used at the last minute ×: Adjacent dots are blurred and mixed and cannot be used 《Wrinkles, curls》 Pick up the printed matter immediately after printing and visually check whether wrinkles or curls have occurred due to irradiation or curing. By 3
Graded evaluation: good: no wrinkles, no curl Δ: almost good (somehow practically acceptable) x: bad, wrinkles on the printed matter and curl

[0058]

[Table 2]

[0059]

[Table 3]

[0060]

[Table 4]

[0061]

[Table 5]

[0062]

According to the constitution of the present invention, no wrinkles or curls are generated in the recording materials of any materials, and there is no color mixing,
High-definition printed matter can be obtained.

Claims (8)

[Claims] 1. An ink jet ink which is curable by actinic rays and which contains substantially no solvent and contains a water repellent. 2. A surface tension of 3 × 10 ^{−4 to} 5 × 10 ⁻⁴ N /
The inkjet ink according to claim 1, wherein the ink is cm. 3. The viscosity at 25 ° C. is 35 to 200 mP.
The inkjet ink according to claim 1 or 2, wherein the inkjet ink is a.s. 4. The inkjet according to claim 1, 2 or 3, wherein one or more kinds of a photopolymerizable monofunctional monomer or oligomer and a bifunctional or higher functional polyfunctional photopolymerizable monomer or oligomer are used in combination. Ink. 5. A recording head having at least one nozzle capable of selectively controlling the ejection of ink droplets by using the ink according to any one of claims 1 to 4. An image forming method comprising heating to -100 ° C. and ejecting. 6. A final printed material on which an image is formed by the image forming method according to claim 5, and the recording material is a plastic film. 7. A final printed matter on which an image is formed by the image forming method according to claim 5 and the recording material is a shrink film. 8. A final printed material on which an image is formed by the image forming method according to claim 5, and the recording material is an adhesive label.