JP2003251798A - Imaging method, printed matter and recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging method through ink jet recording, a printed matter and a recorder in which a high resolution image having an excellent character quality can be recorded on any recording material while preventing color mixing, cockling or curling. <P>SOLUTION: In the imaging method where an active light beam curing ink is ejected onto a recording material using a recording head having nozzles capable of selective ejection control of ink drop, the ink contains at least one kind of oxcetane compound, and at least one kind of compound selected from epoxy compound and vinylether compound as a photopolymerization compound, wherein the ratio of the oxcetane compound to the entire ink composite is 65-95 mass%. <P>COPYRIGHT: (C)2003,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, a printed matter and a recording apparatus by an ink jet recording method capable of stably reproducing a high definition image on any recording material without shrinkage of the recording material.

[0002]

2. Description of the Related Art In recent years, the inkjet recording method has been simple and easy.
Since it is possible to create images at low cost, it has been applied to various printing fields such as photography, various printing, marking, and special printing such as color filters. In particular, a recording device that emits and controls fine dots, and ink and ink absorption with improved color reproduction range, durability, emission suitability, coloring of color materials, and surface gloss have been dramatically improved. Using special paper,
It is also possible to obtain image quality comparable to silver salt photography. 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 provided.

However, the ink jet system requiring special paper has problems that the recording medium is limited and the cost of the recording medium is increased. Therefore, many attempts have been made to record on a transfer medium different from dedicated paper by an inkjet method. Specifically, 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 in which cross-linking is performed by ultraviolet (UV) light after recording. Is.

Among them, the UV ink jet system has been attracting attention in recent years because it has a relatively low odor as compared with the solvent type ink jet system and can perform recording on a recording medium having a fast drying property and no ink absorbing property. Fair 5-
54667, JP-A-6-200204, Special Table 200
No. 0-504778, a UV curable inkjet ink is disclosed.

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 a high-definition image is formed on all recording materials. Is impossible.

Further, the ink used in the conventional UV ink jet system has a problem that the recording material tends to shrink. In particular, in thin film plastic films used in soft packaging such as food packaging and adhesive labels, shrinkage is particularly likely to occur, and as a result, the UV inkjet method has not yet been put to practical use in soft packaging printing and label printing. is the current situation.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide excellent character quality for all recording materials without causing color mixing.
An object of the present invention is to provide an image forming method, a printed matter, and a recording apparatus by an inkjet recording method capable of recording a high-definition image and without causing wrinkles and curls of the printed matter.

[0008]

The above objects of the present invention have been achieved by the following constitutions.

1. In a recording head having at least one nozzle capable of selectively controlling ejection of ink droplets, in an image forming method of ejecting an ink cured by an actinic ray onto a recording material, at least one oxetane compound is used as a photopolymerizable compound. An image is formed using an ink containing at least one compound selected from the group consisting of epoxy compounds and vinyl ether compounds, and the proportion of the oxetane compound in the total ink composition is 65 to 95% by mass. Image forming method.

2. 0.001 after the ink has landed
The method for forming an image as described in the item 1, wherein the actinic ray is irradiated for about 2.0 seconds.

3. 3. The image forming method as described in 1 or 2 above, wherein the total ink film thickness after the ink has landed and irradiated with actinic rays and cured is 2 to 20 μm.

4. Item 4. The image forming method described in any one of Items 1 to 3, wherein the amount of ink droplets ejected from each nozzle of the recording head is 2 to 15 pl.

5. Any one of the above items 1 to 4, wherein at least one color of the ink is white ink.
The image forming method according to item.

6. Using a non-absorbent recording material,
A printed matter produced by the image forming method according to any one of items 5.

7. 7. The printed matter according to the above item 6, wherein the surface energy of the non-absorbent recording material is 35 to 60 dyn / cm.

8. In the recording apparatus used in the image forming method according to any one of items 1 to 5, the peak illuminance in a wavelength range effective for curing actinic rays is 0.1 to 50 mW.
A recording device characterized by being / cm ² .

9. The recording apparatus used for producing the printed matter as described in 6 or 7, wherein the peak illuminance in a wavelength region effective for curing actinic rays is 0.1 to 50 mW / cm ² .

10. In the recording apparatus used in the image forming method according to any one of items 1 to 5, the peak illuminance in a wavelength range effective for curing actinic rays is 0.1 to 300.
A recording device characterized by being 0 mW / cm ² .

11. In the recording apparatus used for producing the printed matter according to 6 or 7, the peak illuminance in a wavelength range effective for curing actinic rays is 0.1 to 3000 mW / cm.
A recording device characterized by being ² .

12. The recording head and ink are
The recording apparatus according to any one of items 8 to 11, wherein the recording device is heated to -100 ° C to eject the ink.

The present invention will be described in detail below. First, the ink used in the present invention will be described.

The composition of the ink according to the present invention contains at least one colorant, a photoinitiator, an oxetane compound, an epoxy compound or a vinyl ether compound, and may also contain other components depending on its use.

In the ink according to the present invention, the proportion of the oxetane compound in the entire ink composition is 65 to 95% by mass.
Is preferred. Japanese Patent Laid-Open No. 2001-220526 discloses an energy ray-curable ink composition for an inkjet recording method, which contains an oxetane compound, but the present inventor has made the ratio of the oxetane compound to the total ink composition 65 to 95. By adjusting the amount to be% by mass, not only the curing speed of the ink described in the above specification is increased, but also in the ink jet recording in which the thickness of the printed ink film becomes thicker than in the normal printing, the ink that occurs during the curing of the ink. It has been newly found that curling and wrinkling of the recording material due to shrinkage can be significantly reduced. Furthermore, it was also found that by setting the proportion of the oxetane compound in the entire ink composition to 65 to 95% by mass, the ink ejection property is very stable and a reproducible and high-definition image can be formed.

Conventionally, in the field of flexible packaging printing and label printing, actinic ray-curable ink jet recording has not been put to practical use from the viewpoint of wrinkles generated in recording materials and ejection stability. By adopting the constitution of the invention, the effect is sufficiently exerted in those fields.

Further, Japanese Laid-Open Patent Publication No. 9-31186 discloses a fast-curing printing ink containing an oxetane compound, but it is completely unsuitable to apply the proposed constitution to an ink jet recording system. It was possible.

First, the oxetane compound according to the present invention will be described. The oxetane compound according to the present invention is
It means a compound having an oxetane ring, and is, for example, JP 2
Known oxetane compounds such as those described in 001-220526 and JP 2001-310937 A can be used.

In the oxetane compound according to the present invention,
When a compound having 5 or more oxetane rings is used, the viscosity of the ink composition becomes high, which makes it difficult to handle, and the glass transition temperature of the ink composition becomes high. It will not be enough. The compound having an oxetane ring used in the present invention is
A compound having 1 to 4 oxetane rings is preferable.

Specific examples of the compound having an oxetane ring according to the present invention will be described below, but the present invention is not limited thereto.

Examples of compounds having one oxetane ring include compounds represented by the following general formula (1).

[0030]

[Chemical 1]

In the general formula (1), R ¹ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group and a butyl group, a fluoroalkyl group having 1 to 6 carbon atoms, and an allyl group. , An aryl group, a furyl group or a thienyl group. R ² is an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group and a butyl group, a 1-propenyl group, a 2-propenyl group, a 2-methyl-1-propenyl group, a 2-methyl- group. 2-propenyl group, 1-butenyl group,
2-butenyl group, alkenyl group having 2 to 6 carbon atoms such as 3-butenyl group, phenyl group, benzyl group, fluorobenzyl group, methoxybenzyl group, group having aromatic ring such as phenoxyethyl group, ethylcarbonyl group, Propylcarbonyl group, butylcarbonyl group, etc., C2-C6 alkylcarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, etc., C2-C6
6 alkoxycarbonyl groups, or N-C2-C6 groups such as ethylcarbamoyl group, propylcarbamoyl group, butylcarbamoyl group and pentylcarbamoyl group
And an alkylcarbamoyl group. As the oxetane compound used in the present invention, it is particularly preferable to use a compound having one oxetane ring because the resulting composition has excellent tackiness, low viscosity and excellent workability.

An example of the compound having two oxetane rings is a compound represented by the following general formula (2).

[0033]

[Chemical 2]

In the general formula (2), R ¹ is the same group as that in the general formula (1). R ³ is, for example, a linear or branched alkylene group such as ethylene group, propylene group, butylene group, poly (ethyleneoxy) group,
Linear or branched unsaturated hydrocarbon group such as poly (propyleneoxy) group or linear or branched poly (alkyleneoxy) group, propenylene group, methylpropenylene group, butenylene group, or carbonyl group or carbonyl group An alkylene group containing a group, an alkylene group containing a carboxyl group, an alkylene group containing a carbamoyl group, and the like.

Further, as R ³ , the following general formula (3),
A polyvalent group selected from the groups represented by (4) and (5) can also be mentioned.

[0036]

[Chemical 3]

In the general formula (3), R ⁴ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group or a butyl group, a methoxy group, an ethoxy group, a propoxy group or a butoxy group. It is an alkoxy group having 1 to 4 carbon atoms such as a group, a halogen atom such as a chlorine atom and a bromine atom, a nitro group, a cyano group, a mercapto group, a lower alkylcarboxyl group, a carboxyl group, or a carbamoyl group.

[0038]

[Chemical 4]

In the general formula (4), R ⁵ is an oxygen atom, a sulfur atom, a methylene group, NH, SO, SO ₂ or C.
It represents (CF ₃ ) ₂ or C (CH ₃ ) ₂ .

[0040]

[Chemical 5]

In the general formula (5), R ⁶ is a methyl group, an ethyl group, a propyl group, a butyl group or the like having 1 to 4 carbon atoms.
Is an alkyl group or an aryl group. n is 0 to 2
It is an integer of 000. R ⁷ is a methyl group, an ethyl group, a propyl group, a butyl group, an alkyl group having 1 to 4 carbon atoms, or an aryl group. Examples of R ^{7 also} include a group selected from the groups represented by the following general formula (6).

[0042]

[Chemical 6]

In the general formula (6), R ⁸ is a methyl group, an ethyl group, a propyl group, a butyl group or the like having 1 to 4 carbon atoms.
Is an alkyl group or an aryl group. m is 0 to 1
00 is an integer.

The following compounds may be mentioned as specific examples of the compound having two oxetane rings.

[0045]

[Chemical 7]

Exemplified compound 1 is a compound in which R ¹ is an ethyl group and R ³ is a carboxyl group in the general formula (2). Further, Exemplified Compound 2 is a compound in which, in the general formula (2), R ¹ is an ethyl group, R ³ is the general formula (5), R ⁶ and R ⁷ are methyl groups, and n is 1.

Among the compounds having two oxetane rings, preferred examples other than the above compounds are compounds represented by the following general formula (7). In general formula (7), R ¹ has the same meaning as R ¹ in the general formula (1).

[0048]

[Chemical 8]

As an example of the compound having 3 to 4 oxetane rings, a compound represented by the following general formula (8) can be given.

[0050]

[Chemical 9]

[0051] In general formula (8), R ¹ is the same meaning as R ¹ in the general formula (1). R ⁹ is, for example, a branched alkylene group having 1 to 12 carbon atoms such as the groups represented by the following A to C, a branched poly (alkyleneoxy) group such as the group represented by the following D, or the following E. Examples thereof include branched polysiloxy groups such as the groups shown. j is 3 or 4.

[0052]

[Chemical 10]

In the above A, R ¹⁰ is a lower alkyl group such as a methyl group, an ethyl group or a propyl group. Moreover, in said D, p is an integer of 1-10.

Exemplified Compound 3 is mentioned as an example of the compound having 3 to 4 oxetane rings.

[0055]

[Chemical 11]

Further, examples of the compound having 1 to 4 oxetane rings other than those described above include compounds represented by the following general formula (9).

[0057]

[Chemical 12]

[0058] In the general formula (9), R ⁸ has the same meaning as R ⁸ in the general formula (6). R ¹¹ is an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group or a butyl group, or a trialkylsilyl group, and r is 1 to 4.

The following compounds are preferred specific examples of the oxetane compound used in the present invention.

[0060]

[Chemical 13]

The method for producing each of the above-mentioned compounds having an oxetane ring is not particularly limited and may be a conventionally known method. For example, Pattison (DB Pattiso) can be used.
n, J. Am. Chem. Soc. , 3455, 79
(1957)) disclosed is a method for synthesizing an oxetane ring from a diol. In addition to these, compounds having 1 to 4 oxetane rings having a high molecular weight of about 1000 to 5000 are also included. The following compounds are mentioned as an example of these concrete compounds.

[0062]

[Chemical 14]

Next, the epoxy compound according to the present invention will be described. The epoxy compound according to the present invention is, for example, JP 2001-55507 A or JP 2001-318 A.
92, JP 2001-40068, JP 2001-31
All known epoxy compounds shown in 0938 and the like can be used.

Preferred aromatic epoxides are:
A diglycidyl ether or a polyglycidyl ether produced by reacting a polyhydric phenol having at least one aromatic nucleus or its alkylene oxide adduct with epichlorohydrin, for example, diphenol of bisphenol A or its alkylene oxide adduct. Examples thereof include glycidyl ether or polyglycidyl ether, diglycidyl ether or polyglycidyl ether of hydrogenated bisphenol A or its alkylene oxide adduct, and novolac type epoxy resin. Examples of the alkylene oxide include ethylene oxide and propylene oxide.

As the alicyclic epoxide, at least 1
A cyclohexene oxide- or cyclopentene oxide-containing compound obtained by epoxidizing a compound having a cycloalkane ring such as cyclohexene or cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peroxide. preferable.

Preferred aliphatic epoxides include diglycidyl ethers or polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, and typical examples thereof include ethylene glycol diglycidyl ether and propylene glycol. Diglycidyl ether or diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, polyglycidyl ether of polyhydric alcohol such as di- or triglycidyl ether of glycerin or its alkylene oxide adduct,
Examples thereof include diglycidyl ether of polyethylene glycol or an alkylene oxide adduct thereof, polypropylene glycol or diglycidyl ether of a polyalkylene glycol such as diglycidyl ether of an alkylene oxide adduct thereof. Examples of the alkylene oxide include ethylene oxide and propylene oxide.

Of these epoxides, in consideration of the rapid curing property, aromatic epoxides and alicyclic epoxides are preferable, and alicyclic epoxides are particularly preferable. In the present invention, one of the above epoxides may be used alone with the oxetane compound, but two or more thereof may be used in appropriate combination.

Next, the vinyl ether compound according to the present invention will be described. The vinyl ether compound according to the present invention may be any known vinyl ether compound, for example, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether. Di- or trivinyl ether compounds such as hexanediol divinyl ether, cyclohexane dimethanol divinyl ether, trimethylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether A Le, cyclohexanedimethanol monovinyl ether, n- propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether -O- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

Of these vinyl ether compounds, divinyl ether compounds or trivinyl ether compounds are preferable, and divinyl ether compounds are particularly preferable, in consideration of curability, adhesion and surface hardness. In the present invention, one kind of the above vinyl ether compounds may be used alone together with the oxetane compound, but two or more kinds may be appropriately combined and used.

Examples of the photoinitiator that can be used in the present invention include all known photoacid generators.

As the photoacid generator, for example, a chemically amplified photoresist or a compound used for photocationic polymerization is used (Organic Materials Research Group, "Organic Materials for Imaging", Bushin Publishing ( 1993
Year), pp. 187-192). Examples of compounds suitable for the present invention are given below.

[0072] First, diazonium, ammonium, Yo - Doniumu, sulfonium, B aromatic onium compounds such as phosphonium ^{_{(C 6 F 5) 4 -}} , PF 6 -, AsF 6 -,
Mention may be made of SbF ₆ ⁻ and CF ₃ SO ₃ ⁻ salts.

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

[0074]

[Chemical 15]

Secondly, a sulfonated compound which generates a sulfonic acid can be mentioned, and its specific compound is exemplified below.

[0076]

[Chemical 16]

Thirdly, a halide capable of photogenerating hydrogen halide can also be used, and specific compounds thereof will be exemplified below.

[0078]

[Chemical 17]

Fourthly, an iron allene complex can be mentioned.

[0080]

[Chemical 18]

The ink according to the present invention is disclosed in JP-A-8-248.
561 and Japanese Patent Laid-Open No. 9-034106,
It is preferable to contain an acid proliferating agent that newly generates an acid by the acid that has already been known and is generated by irradiation with actinic rays. The use of an acid multiplying agent is preferable because it is possible to improve ejection stability and reduce curling and wrinkling of the recording material.

When coloring the ink composition according to the present invention, 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 pigments that can be preferably used in the present invention are listed below. C. I Pigment Yellow-1, 3, 1
2, 13, 14, 17, 81, 83, 87, 95, 10
9, 42, C.I. I Pigment Orange-1
6, 36, 38, C.I. I Pigment Red-
5, 22, 38, 48: 1, 48: 2, 48: 4, 4
9: 1, 53: 1, 57: 1, 63: 1, 144, 14
6, 185, 101, C.I. I Pigment Vio
let-19, 23, C.I. I Pigment Blu
e-15: 1, 15: 3, 15: 4, 18, 60, 2
7, 29, C.I. I Pigment Green-7,
36, C.I. I Pigment White-6, 1
8, 21, C.I. I Pigment Black-7, and in the present invention, it is preferable to use a white ink in order to improve the color hiding property on a transparent substrate such as a plastic film. In particular, in soft packaging printing and label printing, it is preferable to use a white ink, but since the ejection amount is large, from the viewpoints of the ejection stability described above and the occurrence of curling and wrinkling of the recording material, the amount used is naturally There is a limit.

For the dispersion of the above pigment, for example, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, a paint shaker, or the like can be used. Further, it is possible to add a dispersant when the pigment is dispersed. It is preferable to use a polymer dispersant 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 preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment. A solvent or a polymerizable compound is used as the dispersion medium, but the irradiation ray-curable ink used in the present invention is preferably solvent-free because it reacts and cures immediately after the ink impacts. 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 selected from a polymerizable compound, not a solvent, and a monomer having the lowest viscosity among them.

The dispersion of the pigment is carried out by adjusting the average particle diameter of the pigment particles to 0.
08-0.5 μm is preferable, and the maximum particle size is 0.3-10 μm, preferably 0.3-3 μm, the selection of pigment, dispersant, dispersion medium, dispersion conditions, and filtration conditions are appropriately set. To do. By controlling the particle size, clogging of the head nozzle can be suppressed, and the ink storage stability, ink transparency, and curing sensitivity can be maintained.

In the ink according to the present invention, the coloring material concentration is preferably 1% by mass to 10% by mass of the total ink.

Various additives other than those described above can be used in the ink according to the present invention. For example, in order to enhance the storage stability of the ink composition, a polymerization inhibitor of 200 to
20000 ppm can be added. 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, if necessary, a surfactant, a leveling additive, a matting agent, a polyester resin for adjusting the film physical properties, a polyurethane resin, a vinyl resin, an acrylic resin, a rubber resin,
Waxes can be added. In order to improve the adhesion to the recording medium, it is also effective to add an extremely small amount of organic solvent. In this case, it is effective to add it within a range that does not cause problems of solvent resistance and VOC.
It is in the range of ~ 5%, preferably 0.1-3%.
In addition, a radical polymerizable monomer and an initiator are combined,
It is also possible to use a radical / cation hybrid type curing ink.

In the image forming method of the present invention, the ink composition is ejected onto a recording material by an ink jet recording method to draw an image, and then the ink is cured by irradiating with actinic rays such as ultraviolet rays.

In the present invention, the total ink film thickness after the ink has landed and irradiated with actinic rays and cured is 2 to 20 μm.
Is preferred. In the actinic ray-curable inkjet recording in the screen printing field, the total ink film thickness is 20μ.
Although the current value is more than m, in the flexible packaging printing field where the recording material is often a thin plastic material, not only the curling and wrinkling problems of the recording material described above but also the stiffness and texture of the entire printed matter It cannot be used because it has the problem of changing.

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

Further, in the present invention, it is preferable that the amount of droplets ejected from each nozzle is 2 to 15 pl. In order to form a high-definition image, it is necessary that the droplet amount is within this range. However, when ejecting with this droplet amount, the ejection stability described above becomes particularly severe, and an acid multiplying agent is essential. Become.

In the image recording method of the present invention, the irradiation condition of the generated light rays is 0.001 to 2.0 after the ink is landed.
Irradiation with actinic rays is preferably performed for 2 seconds, more preferably 0.001 to 1.0 seconds. In order to form a high-definition image, it is especially 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 time has elapsed after the ink has landed. Furthermore,
Curing is completed by another light source that is not driven. US Pat. No. 6,145,979 discloses, 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. There is. Any of these irradiation methods can be used in the image forming method of the present invention.

Further, the irradiation of the active ray is divided into two stages. First, the active ray is irradiated by the above-mentioned method within 0.001 to 2.0 seconds after the ink has landed, and after the completion of all printing, the active ray is further irradiated. The method of irradiating is also one of the preferable embodiments. By dividing the irradiation of actinic rays into two stages, it becomes possible to further suppress the shrinkage of the recording material that occurs during ink curing.

In the present invention, in the wavelength region effective for curing,
Maximum illuminance is 0.1-50 mW / cm ²Low illumination active light
It is preferable to use lines. Conventionally, UV inkjet
With this method, the spread of dots and the bleeding after ink landing are suppressed.
Therefore, the maximum illuminance in the wavelength range effective for curing is 50 m.
W / cm²It is common to use light sources with high illuminance
Met. However, with these light sources,
For shrink labels, etc., the recording material does not shrink much.
However, the current situation is that it is too large to use. Book
In the invention, by using an acid multiplying agent, the wavelength effective for curing is increased.
The maximum illuminance in the area is 0.1 to 50 mW / cm²Low light
High-definition images can be formed even with a small amount of actinic light.
There is also no shrinkage of the recording material.

As an example of a light source used for actinic ray irradiation,
Low-pressure mercury lamp, UV laser, xenon flash lamp, insect trap, black light, germicidal lamp, cold cathode tube, L
Examples include, but are not limited to, EDs.

In the present invention, it is also effective to use an actinic ray having a maximum illuminance of 50 to 3000 mW / cm ² in a wavelength range effective for curing. Although it is a light source of high illuminance used for conventional UV inkjet recording, there is a problem of shrinkage of the recording material as described above, and substantially UV inkjet recording has not been used in the field of flexible packaging printing / label printing. With the structure of the present invention, this problem is solved, and it becomes possible to form a high-definition image on various plastic films even with the conventionally used high-illuminance light source. Examples of the light source include, but are not limited to, a high pressure mercury lamp, a metal halide lamp, and an electrodeless UV lamp.

As the recording material that can be used in the present invention, in addition to ordinary uncoated paper, coated paper and the like, various non-absorbent plastics and films thereof used for so-called soft packaging can be used. Examples of the film include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film. Other plastics include polycarbonate, acrylic resin, ABS, polyacetal, PVA,
Rubber etc. can be used. Further, it is also applicable to metals and glasses. Among these recording materials, the constitution of the present invention is effective especially when an image is formed on a PET film, an OPS film, an OPP film, an ONy film, or a PVC film, which can be shrunk by heat.
In these base materials, not only the film is easily curled and deformed due to the curing shrinkage of the ink and the heat generated during the curing reaction, but also the ink film is difficult to follow the shrinkage of the base material.

It has been a problem in the past that the surface energies of these various plastic films are greatly different and the dot diameter after the ink has landed varies depending on the recording material. With the constitution of the present invention, the surface energy including the OPP film having a low surface energy, the OPS film, and the PET having a relatively large surface energy is 35.
A good and high-definition image can be formed on a wide range of recording materials of -60 dyn / cm.

In the present invention, a long material (web) is used in terms of recording material costs such as packaging costs and production costs, print production efficiency, and compatibility with prints of various sizes.
It is advantageous to use different recording materials.

[0101]

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

Example 1 << Preparation of Ink Composition >> Ink composition set 1 having the constitution shown in Table 1 (comparative example) and ink composition sets 2-4 having the constitution shown in Tables 2 to 4 Invention) was prepared.

[0103]

[Table 1]

[0104]

[Table 2]

[0105]

[Table 3]

[0106]

[Table 4]

Details of each compound shown in Tables 1 to 4 are as follows. K: Dark black ink C: Dark cyan ink M: Dark magenta ink Y: Dark yellow ink Lk: Light black ink Lc: Light cyan ink Lm: Light magenta ink Ly: Light yellow ink color material 1: C.I. I. pigment Black-7 coloring material 2: C.I. I. Pigment Blue-15: 3 Colorant 3: C.I. I. pigment Red-57: 1 coloring material 4: C.I. I. Pigment Yellow-13 Celoxide 2021P: Daicel Chemical Industry Co., Ltd. OXT-101: Toa Gosei Chemical Co., Ltd. OXT-212: Toa Synthetic Chemical Co., Ltd. OXT-121: Toa Synthetic Chemical Co., Ltd. RAPI-CURE DVE-3: ISPE Japan BBI102 manufactured by Midori Kagaku Co., Ltd. MPI103 manufactured by Midori Kagaku Co., Ltd. * 1: 2-Methoxy-4-phenylbenzenediazonium hexafluorophosphate manufactured by Midori Kagaku Co., Ltd.

[0108]

[Chemical 19]

<Inkjet image forming method> An inkjet recording apparatus equipped with a piezo type inkjet nozzle was loaded with each of the ink composition sets prepared above, and Table 5
Width 600 mm, length 10 with surface energy described in
The following image recordings were continuously performed on each recording material having a length of 00 m. The ink supply system consisted 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. The anterior chamber tank and the head portion were thermally insulated and heated at 50 ° C. The piezo head
720x720d with 2-15 pl multi-size dots
Each ink was continuously ejected by driving so as to eject at a resolution of pi. 0.15 seconds after landing, curing treatment was performed under the irradiation conditions shown in Table 5. After recording, the total ink film thickness was measured and found to be in the range of 2.3 to 13 μm. The term "dpi" in the present invention means the number of dots per 2.54 cm.

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[Table 5]

Details of the abbreviations of the recording materials listed in Table 5 are as follows. OPP: oriented polypropylen
e PET: polyethylene terephth
ate ONy: Oriented nylon PVC: polyvinyl chloride The details of the irradiation light source shown in Table 5 are as follows.

Irradiation light source 1: 120 W / cm metal halide lamp (MAL400NL manufactured by Nippon Battery Co., Ltd.) Irradiation light source 2: electrodeless UV lamp (F450 series manufactured by Fusion UV Systems Japan Co., Ltd.) Irradiation power supply 3: 80 W / cm high pressure mercury lamp (Japan Battery Company HN-64NL) << Evaluation of Inkjet Recorded Image >> The following evaluations were performed on each image recorded by the image forming method. Each evaluation was performed on a sample 10 m after image recording and a sample 500 m after continuous image ejection.

(Evaluation of character quality) At the target K density,
Eight-point characters were printed, and the printed image was observed with a magnifying glass and the shape of one dot for each color with a magnifying glass, and the character quality was evaluated according to the following evaluation criteria.

⊚: There is no roughness and the dot shape is a perfect circle. ◯: There is a slight roughness, but the dot shape is a perfect circle. Δ: There is a roughness and the dot shape is somewhat disordered, but acceptable. The range is x: Roughness is recognized, the dot shape is bad, and it is outside the practically allowable range (evaluation of color mixing (bleeding)). An image pattern in which 8-point characters are arranged on a magenta solid image with a target density and One dot of each color was output, the quality after 10 minutes was magnified and observed with a magnifying glass, and the color mixture was evaluated according to the following evaluation criteria.

⊚: There is no color mixing and the dot shape is a perfect circle. ◯: A slight color mixing is recognized, but the dot shape is a perfect circle. Δ: Color mixing is recognized, and the dot shape is somewhat disordered. However, it is within the allowable range. X: Color mixing is recognized, the dot shape is bad, and it is out of the practically allowable range (evaluation of wrinkles and curls of printed matter). Immediately after printing 10 m and 500 m, irradiation and curing of each printed matter Then, whether or not wrinkles or curls were generated was visually observed, and evaluated according to the following evaluation criteria.

◯: No wrinkles or curls are generated, which is good Δ: Some wrinkles or curls are observed, but is in a practically acceptable range ×: Strong wrinkles or curls are observed in printed matter, which is practical Table 6 shows the evaluation results obtained by the above problems.

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[Table 6]

As is clear from Table 6, the image recording method using the ink composition set according to the present invention is excellent in character quality, does not cause color mixing, and produces a high-definition image for all recording materials. It can be seen that the printed matter can be recorded and there is no wrinkle or curl in the printed matter.

Example 2 << Preparation of Ink Composition >> Ink composition set 5 having the constitution shown in Table 7 (Comparative Example) and ink composition sets 6 to 8 having the constitution shown in Tables 8 to 10 Invention) was prepared.

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[Table 7]

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[Table 8]

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[Table 9]

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[Table 10]

Details of each compound shown in Tables 7 to 10 are as follows.
It is as follows. Coloring material 1: C.I. I. pigment Black-7 coloring material 2: C.I. I. Pigment Blue-15: 3 Colorant 3: C.I. I. pigment Red-57: 1 coloring material 4: C.I. I. Pigment Yellow-13 Coloring Material 5: Titanium Oxide (Anatase Type Average Particle Size 0.20
μm) Celoxide 2021P: Daicel Chemical Industries, Ltd. OXT-121: Toa Gosei Chemical Company, OXT-211: Toa Gosei Chemical Company, OXT-221: Toa Gosei Chemical Company * 2: RHODORSIL PHOTOINITIAT
OR 2074 (made by Rhodia Japan)

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[Chemical 20]

<< Inkjet Image Forming Method >> An inkjet recording apparatus having a piezo type inkjet nozzle was loaded with each of the ink composition sets prepared above, and Table 1
600 mm in width and 1 in length having the surface energy described in 1.
The following image recordings were continuously carried out on each 000 m long recording material. 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. The anterior chamber tank and the head portion were thermally insulated and heated at 70 ° C. The piezo head
720x720d with 2-15 pl multi-size dots
Each ink was continuously ejected by driving so as to eject at a resolution of pi. 0.2 seconds after landing, curing treatment was performed under the irradiation conditions shown in Table 11. After recording, the total ink film thickness was measured, and as compared with Example 1, the white ink was used, and the thickness became thicker, and was in the range of 2.3 to 19.6 μm.

[0127]

[Table 11]

The details of the abbreviations of the recording materials other than those described in Example 1 in Table 11 are as follows.

OPS: Oriented Polystyrene The details of the irradiation light source shown in Table 11 are as follows.

Irradiation light source 4: Black light (manufactured by Nippon Electric Co., Ltd.) Irradiation light source 5: Insect light (manufactured by Harrison Toshiba Lighting Co., Ltd.)
FL20S / BL type) Irradiation light source 6: Cold cathode tube (manufactured by Hibeck Co., Ltd.) << Evaluation of Inkjet Recorded Image >> For each image recorded by the above-mentioned image forming method, 10 of continuous image recording
According to the method described in Example 1, the sample after m and the sample after 500 m were evaluated for character quality, color fringing, printed wrinkles, and curl, and the obtained results are shown in Table 12.

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[Table 12]

As is clear from Table 12, similar to the results of Example 1, the image recording method using the ink composition set according to the present invention was excellent in character quality and color mixing for all recording materials. It can be seen that a high-definition image can be recorded without any occurrence of wrinkles and that no wrinkles or curls are generated on the printed matter.

[0133]

INDUSTRIAL APPLICABILITY According to the present invention, an ink jet recording having excellent character quality, capable of recording a high-definition image with no occurrence of color mixing, and no wrinkling or curling of printed matter can be performed on any recording material. The image forming method, the printed matter, and the recording apparatus according to the method can be provided.

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) B41J 3/04 101Y

Claims (12)

[Claims] 1. An image forming method in which an ink curable by an actinic ray is ejected onto a recording material in a recording head having at least one nozzle capable of selectively ejecting ink droplets, and at least 1 is used as a photopolymerizable compound. Image using an ink containing one oxetane compound and at least one compound selected from an epoxy compound and a vinyl ether compound, and the proportion of the oxetane compound in the entire ink composition is 65 to 95% by mass. An image forming method characterized by forming. 2. After the ink has landed, 0.001 to
The image forming method according to claim 1, wherein the actinic ray is irradiated for 2.0 seconds. 3. The image forming method according to claim 1, wherein the total ink film thickness after the ink has landed and is irradiated with an actinic ray and cured is 2 to 20 μm. 4. The image forming method according to claim 1, wherein the amount of ink droplets ejected from each nozzle of the recording head is 2 to 15 pl. 5. The image forming method according to claim 1, wherein at least one color of the ink is white ink. 6. A non-absorptive recording material is used to claim 1.
5. A printed matter produced by the image forming method according to any one of 5 above. 7. The printed matter according to claim 6, wherein the surface energy of the non-absorptive recording material is 35 to 60 dyn / cm. 8. The recording apparatus used in the image forming method according to claim 1, wherein a peak illuminance in a wavelength range effective for curing actinic rays is 0.1 to 50 mW /
A recording device characterized by being cm ² . 9. The recording apparatus used for producing the printed matter according to claim 6 or 7, wherein peak illuminance in a wavelength region effective for curing actinic rays is 0.1 to 50 mW / cm ^2. Recording device. 10. The recording apparatus used in the image forming method according to claim 1, wherein a peak illuminance in a wavelength range effective for curing actinic rays is 0.1 to 3000.
A recording device characterized by being mW / cm ² . 11. A recording apparatus used for producing a printed matter according to claim 6 or 7, wherein a peak illuminance in a wavelength range effective for curing actinic rays is 0.1 to 3000 mW / cm ^2.
A recording device characterized by being. 12. The recording head and ink are set to 35 to 35.
The recording apparatus according to claim 8, wherein the recording apparatus is heated to 100 ° C. to eject the ink.