Manufacturing method of recorded matter

Abstract

To provide a recording method capable of giving a recorded matter improved in detachability between a recorded face and a non-recorded face, and suppressed in change of texture of an obtained recorded matter.SOLUTION: A method of producing recorded matter comprises: a first jet step of jetting first ink which is a radioactive ray-curable inkjet composition to make it adhere to a recording medium; a first irradiation step of irradiating the first ink adhering to the recording medium with a radioactive ray to obtain a cured coated film of the first ink; a second jet step of jetting second ink which is a radioactive ray-curable inkjet composition to make it adhere onto a cured film of the first ink so that the Duty becomes 1% or more and 20% or less; a second irradiation step of irradiating the second ink adhering to the recording medium with a radioactive ray to cure the second ink to obtain a recorded matter; and a laminating step of laminating the recorded matter so that a recorded face to which the first ink and the second ink adhere faces to a non-recorded face to which the first ink and the second ink do not adhere.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a recorded matter. [Background technology]

[0002] Inkjet recording methods are capable of recording high-definition images with a relatively simple device, and have been rapidly developed in various fields. Among them, various studies have been conducted on methods of forming multiple ink layers and performing recording. For example, Patent Document 1 discloses an ink set that includes a colored ink composition containing a specific radical polymerizable compound and a clear ink composition, and that adjusts the content of the polymerization initiator contained in the colored ink composition and the clear ink composition, for the purpose of providing an ink set for forming multiple layers that has excellent image quality and gloss, provides a good surface condition, is excellent in blocking resistance, and can form an image without a tint of the base. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-067770 A Summary of the Invention [Problem to be solved by the invention]

[0004] As described in Patent Document 1, when recording on a film-based recording medium, particularly in an industrial manner, the recording medium after the ink is attached may be wound up in a roll and stored. Patent Document 1 teaches that the clear ink layer is formed as a solid image including the entire area where the image is formed by the image forming process. However, when the clear ink layer is formed as a solid image layer in this way, when the recording medium is stored in a roll, the recording surface on which the clear ink layer or the like is attached and the non-recording surface on the back side thereof stick together. In this case, when the recorded material is unwound from the roll and used, the image may easily peel off from the recording surface at the stuck part or may be left with a mark, which may damage the recorded image. [Means for solving the problem]

[0005] The present invention is a method for producing a recorded material, comprising: a first discharging step of discharging a first ink, which is a radiation curable inkjet composition, and adhering it onto a recording medium; a first irradiation step of irradiating the first ink adhered to the recording medium with radiation to obtain a cured coating film of the first ink; a second discharging step of discharging a second ink, which is a radiation curable inkjet composition, and adhering it onto the cured coating film of the first ink so that a duty is 1% or more and 20% or less; a second irradiation step of irradiating the second ink adhered to the recording medium with radiation to cure the second ink, thereby obtaining a recorded material; and a lamination step of stacking the recorded material so that a recorded surface to which the first ink and the second ink are adhered faces a non-recorded surface to which the first ink and the second ink are not adhered. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram of a recording apparatus that can be used in the present embodiment. [Diagram 2] 1 is a schematic cross-sectional view of a recorded matter according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this, and various modifications are possible without departing from the gist of the present invention. In the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted. Furthermore, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings, unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0008] In this specification, "(meth)acryloyl" means at least one of acryloyl and the corresponding methacryloyl, "(meth)acrylate" means at least one of acrylate and the corresponding methacrylate, and "(meth)acrylic" means at least one of acrylic and the corresponding methacrylic.

[0009] 1. Manufacturing method of recorded matter The method for producing a recorded matter of the present embodiment includes a first discharging step of discharging a first ink, which is a radiation curable inkjet composition, and adhering it onto a recording medium; a first irradiation step of irradiating the first ink adhered to the recording medium with radiation to obtain a cured coating film of the first ink; a second discharging step of discharging a second ink, which is a radiation curable inkjet composition, and adhering it onto the cured coating film of the first ink so that the duty is 1% or more and 20% or less; a second irradiation step of irradiating the second ink adhered to the recording medium with radiation to cure the second ink, thereby obtaining a recorded matter; and a lamination step of stacking the recorded matter so that a recorded surface to which the first ink and the second ink are adhered faces a non-recorded surface to which the first ink and the second ink are not adhered.

[0010] In this embodiment, the second ink is applied to the cured coating of the first ink so that the duty is 1% or more and 20% or less, and thus unevenness corresponding to the duty can be formed on the recording surface. Therefore, when the surface of the recorded matter on which ink is applied (hereinafter also referred to as the "recording surface") and the surface on which ink is not applied (hereinafter also referred to as the "non-recording surface") are laminated, the contact area is reduced, and the recording surface and the non-recording surface can be prevented from tightly adhering to each other. This improves the peelability of the recording surface and the non-recording surface, and prevents marks from remaining on the recording surface and part of the ink layer from adhering to the non-recording surface.

[0011] In addition, by adjusting the duty of the second ink within the above range, it is possible to further reduce the effect of unevenness on image quality, and there is a tendency for changes in the texture of the recorded matter obtained with the first ink to be further suppressed. Each step of the method for producing a recorded matter of this embodiment and the inks used will be described in detail below.

[0012] First, before describing each step, a recording device that can be used in the method for producing a recorded matter of this embodiment will be described with reference to Fig. 1. Fig. 1 shows a schematic diagram of a recording device that can be used in this embodiment.

[0013] 1, a recording apparatus 1 has a first inkjet head 2 that ejects a first ink, a second inkjet head 3 that ejects a second ink, and a recording medium transport mechanism 5. The first inkjet head 2 may have heads 2a to 2d for each type of ink, as shown in the figure. In addition, light sources 4a to 4d for curing the first ink attached to a recording medium 6 are provided downstream of each of the heads 2a to 2d.

[0014] The second inkjet head 3 includes, for example, a head 3a for depositing the second ink, and a light source 4e for curing the second ink deposited on the recording medium 6 downstream thereof.

[0015] The recording medium transport mechanism 5 has, for example, a feed roller 51 and a take-up roller 52. The recording medium is fed out from the feed roller 51 in the transport direction F, and the recorded recording medium is taken up by the take-up roller 52 to form a roll. At this time, the recorded surface and the non-recorded surface of the recorded matter come into contact with each other inside the roll.

[0016] 1.1.First discharge process The first ejection step is a step in which the first ink, which is a radiation curable ink jet composition, is ejected from the first ink jet head 2 and adhered to the recording medium 6. More specifically, the pressure generating means is driven to eject the composition filled in the pressure generating chamber of the ink jet head from the nozzle. This ejection method is also called the ink jet method.

[0017] The inkjet heads 2 and 3 used in the first ejection step and the second ejection step described below include a line head that performs recording by a line method and a serial head that performs recording by a serial method.

[0018] In the line method using a line head, for example, an inkjet head having a width equal to or greater than the recording width of the recording medium is fixed to the recording device. Then, the recording medium is moved in the sub-scanning direction (the vertical direction of the recording medium, the transport direction), and ink droplets are ejected from the nozzles of the inkjet head in conjunction with this movement to record an image on the recording medium.

[0019] In the serial method using a serial head, for example, an inkjet head is mounted on a carriage that can move in the width direction of the recording medium. The carriage is then moved along the main scanning direction (the lateral direction or width direction of the recording medium), and ink droplets are ejected from the nozzle openings of the head in conjunction with this movement, thereby recording an image on the recording medium.

[0020] Among these, from the viewpoint of winding up the recording medium with the ink attached thereto, it is preferable to use the line method in the first ejection step and the second ejection step described below. In the case of the line method, while the recording medium is continuously fed in the sub-scanning direction, recording and radiation are continuously performed by the line head, and the recording medium with the ink attached thereto is wound up downstream. Note that the type of recording device shown in FIG. 1 is the line method.

[0021] The deposition state of the first ink in the first ejection step, such as the duty, is not particularly limited, and can be appropriately adjusted according to the desired image.

[0022] In the method for producing a recorded matter of this embodiment, it is preferable that the first ink is a color ink and the second ink is a clear ink. By applying the first ink, which is a color ink, and then applying the second ink, which is a clear ink, the separation between the recorded surface having the image formed with the first ink and the non-recorded surface is improved, and it is possible to prevent marks from remaining on the recorded surface and prevent part of the ink layer from adhering to the non-recorded surface.

[0023] Here, the term "clear ink" is a concept corresponding to color ink used to color a recording medium, and refers to ink that is not intended for coloring. Specifically, the clear ink is preferably an ink composition containing less than 0.2% by mass of coloring material, and more preferably does not contain any coloring material. On the other hand, the color ink is an ink used to color a recording medium, and preferably contains 0.2% by mass or more of coloring material.

[0024] Furthermore, in the method for producing a recorded matter of this embodiment, another discharge step and another irradiation step may be included before the first discharge step. For example, as the other discharge step and irradiation step, a white ink may be applied to the recorded matter and cured, and the first discharge step may be performed on the white ink layer. This allows a concealing layer or the like to be formed, and a recorded matter with good color development when viewed from the recording surface side can be obtained.

[0025] In another embodiment, for example, as another ejection step and irradiation step, a colored ink may be applied to a recording material and cured to form an image, and then a first ejection step may be performed to apply and cure a white ink to the colored ink layer. This allows a concealing layer or the like to be formed, and a recording material with good color development when viewed from the non-recorded side of a transparent recording medium can be obtained.

[0026] The recording medium is preferably a non-absorbent recording medium. In particular, it is preferable that the recording surface and the non-recording surface of the recording medium used in the present embodiment are both non-absorbent. By using such a recording medium, a recorded matter suitable for label applications can be obtained. In addition, since the recording medium is non-absorbent, the cured coating film of the ink is easily adhered to the non-recording surface, so that the unevenness formed by the second ink acts more effectively, and the releasability of the recorded matter tends to be improved.

[0027] Non-absorbent recording media are not particularly limited, but examples include plastic films and plates such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate, polystyrene, polyurethane, etc.; metal plates such as iron, silver, copper, aluminum, etc.; or metal plates and plastic films produced by vapor deposition of these various metals, alloy plates such as stainless steel and brass, and recording media in which a plastic film such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate, polystyrene, polyurethane, etc. is adhered (coated) to a paper substrate.

[0028] In this embodiment, non-absorbent means that the amount of water absorbed from the start of contact to 30 msec in the Bristow method is 10 mL / m 2 The term "absorbent recording medium" refers to a recording medium that is non-absorbent in this way. The Bristow method is the most widely used method for measuring the amount of liquid absorbed in a short period of time, and is also adopted by the Japan Pulp and Paper Technical Association (JAPAN TAPPI). Details of the test method are described in Standard No. 51 "Paper and paperboard - Liquid absorbency test method - Bristow method" of the "JAPAN TAPPI Paper and Pulp Testing Methods 2000 Edition."

[0029] 1.2.First irradiation process The first irradiation step is a step in which the first ink attached to the recording medium 6 is irradiated with radiation from the light sources 4a to 4d to obtain a cured coating film of the first ink. In the first irradiation step and the second irradiation step described below, the radiation-curable inkjet composition attached to the recording medium is irradiated with radiation. When irradiated with radiation, a polymerization reaction of the monomer is initiated, curing the composition and forming a coating film. At this time, if a polymerization initiator is present, it generates active species (initiation species) such as radicals, acids, and bases, and the polymerization reaction of the monomer is promoted by the function of the initiation species.

[0030] Here, examples of the radiation include ultraviolet rays, infrared rays, visible light, and X-rays. The radiation source is provided downstream of the inkjet head and irradiates the composition with the radiation. The radiation source is not particularly limited, but may be, for example, a UV-LED. By using such a radiation source, the device can be made smaller and the cost reduced. The UV-LED as the ultraviolet ray source is small, so it can be installed in the inkjet recording device.

[0031] 1.3.Second discharge process The second ejection step is a step of ejecting the second ink, which is a radiation curable ink jet composition, from the second inkjet head 3 and depositing it on the cured coating of the first ink so that the duty is within a predetermined range. The duty in the second ejection step is 1% or more and 20% or less, preferably 3% or more and 18% or less, and more preferably 6% or more and 15% or less. A duty of 1% or more improves the peelability between the recorded surface and the non-recorded surface, and can prevent marks from remaining on the recorded surface and adhesion of part of the ink layer to the non-recorded surface. In addition, a duty of 20% or less makes it possible to further reduce the effect of unevenness on image quality, and tends to further suppress changes in the texture of the recorded matter obtained with the first ink.

[0032] In this embodiment, "duty" is a value calculated by the following formula, and means the amount of ink attached to a pixel. Here, a duty of 1% to 20% means that the number of actual printed dots is 1 to 20% for a given pixel (vertical resolution x horizontal resolution). Duty(%) = Actual number of printed dots / (Vertical resolution x Horizontal resolution) x 100 (In the formula, "actual print dot number" is the number of actual print dots per unit area, and "vertical resolution" and "horizontal resolution" are the resolutions per unit area, respectively.)

[0033] 1.4.Second irradiation process The second irradiation step is a step of irradiating the second ink attached to the recording medium 6 with radiation from the light source 4e to cure the second ink, thereby obtaining a recorded matter. This makes it possible to cure the second ink attached onto the cured coating film of the first ink, and to form unevenness according to the duty applied in the second ejection step. The irradiation of radiation can be the same as in the first irradiation step.

[0034] 1.5.Lamination process The lamination step is a step of stacking the recorded matter so that the recorded surface to which the first ink and the second ink are attached faces the non-recorded surface to which the first ink and the second ink are not attached.

[0035] The stacking method in the stacking step is not particularly limited, but examples include stacking single-sheet recorded materials one by one with the recorded surface facing the non-recorded surface, and stacking recorded materials, which are continuously recorded on a long recording medium, with the recorded surface facing the non-recorded surface by winding them up in a roll downstream of the recording device. More specifically, the recorded materials can be wound up into a roll by winding them up on a winding roller 52. In this roll, the recorded materials are stacked and wound up with the recorded surface facing the non-recorded surface.

[0036] By winding it into a roll in this way, the recording surface and the non-recording surface are pressed strongly against each other within the roll, and also rub against each other when rolled. For this reason, the present invention is particularly useful in that it improves the peelability of the recording surface and the non-recording surface, and prevents marks from remaining on the recording surface and prevents part of the ink layer from adhering to the non-recording surface.

[0037] 1.6. First ink and second ink The first ink and the second ink used in this embodiment are both radiation-curable inkjet compositions. The first ink and the second ink are described in detail below, but when there is no need to distinguish between the first ink and the second ink, they are collectively referred to simply as "ink", and when the composition of the first ink or the second ink is specifically mentioned, the subject is clearly stated.

[0038] The ink is not particularly limited as long as it is a radiation-curable inkjet composition. In the present embodiment, the radiation-curable inkjet composition refers to one that is cured by irradiation with radiation. Examples of radiation include ultraviolet rays, electron beams, infrared rays, visible light, and X-rays. Among these, ultraviolet rays are preferred as the radiation, since radiation sources are easily available and widely used, and materials suitable for curing by ultraviolet radiation are easily available and widely used.

[0039] The ink is not particularly limited, but may contain, for example, a polymerizable compound, a photopolymerization initiator, a polymerization inhibitor, a slip agent, a coloring material, a dispersant, etc. As described above, it is preferable that the first ink is a color ink and the second ink is a clear ink. Each component will be described in detail below.

[0040] 1.6.1. Polymerizable compounds The polymerizable compound contains a monofunctional monomer, and may contain a polyfunctional monomer as necessary.

[0041] 1.6.1.2. Monofunctional monomers The monofunctional monomer is not particularly limited, and examples thereof include monofunctional monomers having an alicyclic group, monofunctional monomers having an aromatic group, and monofunctional monomers having a nitrogen-containing heterocycle. Monomers other than these may also be used as the monofunctional monomer.

[0042] By using a monofunctional monomer, as described above, there is an advantage that the adhesion is improved and a recorded matter having excellent stretchability can be obtained. On the other hand, when a recorded surface formed with an ink having high adhesion is laminated with a non-recorded surface, the peelability is likely to decrease due to the high adhesion, and a mark is likely to be left behind. Therefore, the present invention is particularly useful from the viewpoint of obtaining a recorded matter that utilizes the characteristics of the monofunctional monomer while also obtaining a recorded matter that has excellent peelability and is unlikely to leave a mark.

[0043] In particular, when the first ink contains a monofunctional monomer, the content of the monofunctional monomer is preferably 80% by mass or more, more preferably 85 to 99% by mass, and even more preferably 90 to 98% by mass, relative to the total amount of the polymerizable compounds in the first ink. By having the content of the monofunctional monomer be 80% by mass or more, the adhesion and curing property between the ink layer and the recording medium tend to be further improved.

[0044] Furthermore, when the second ink contains a monofunctional monomer, the content of the monofunctional monomer is preferably 80% by mass or more, more preferably 85 to 99% by mass, and even more preferably 90 to 98% by mass, relative to the total amount of the polymerizable compounds in the second ink. When the content of the monofunctional monomer is 80% by mass or more, the adhesion between the coating film of the first ink and the coating film of the second ink and the curing property tend to be further improved. In addition, the coating film of the second ink becomes flexible, which makes it easier to prevent damage to the recorded matter when the laminated recorded matter is processed and used.

[0045] 1.6.1.2.1. Monofunctional monomers containing alicyclic groups The monofunctional monomer having an alicyclic group is not particularly limited, and examples thereof include alicyclic group-containing (meth)acrylates such as dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tert-butylcyclohexanol (meth)acrylate, and 2-(meth)acrylic acid-1,4-dioxaspiro[4,5]dec-2-ylmethyl.

[0046] Among these, dicyclopentenyl (meth)acrylate (DCPA) and isobornyl acrylate (IBXA) are preferable. By using such monomers, the adhesion and abrasion resistance of the obtained coating film tend to be further improved.

[0047] The content of the monofunctional monomer having an alicyclic group is preferably 25 to 55 mass %, more preferably 30 to 50 mass %, and further preferably 35 to 45 mass %, based on the total amount of the polymerizable compounds. When the content of the monofunctional monomer having an alicyclic group is within the above range, the adhesion and abrasion resistance of the obtained coating film tend to be further improved.

[0048] 1.6.1.2.2. Monofunctional monomers with aromatic groups The monofunctional monomer having an aromatic group is not particularly limited, but examples thereof include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, alkoxylated 2-phenoxyethyl (meth)acrylate, ethoxylated nonylphenyl (meth)acrylate, alkoxylated nonylphenyl (meth)acrylate, p-cumylphenol EO-modified (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate.

[0049] Among these, phenoxyethyl acrylate (PEA) is preferred. By using such an aromatic group-containing monofunctional monomer, the solubility of the photopolymerization initiator is improved, and the curing property of the ink tends to be improved. In particular, when an acylphosphine oxide-based photopolymerization initiator or a thioxanthone-based photopolymerization initiator is used, the solubility tends to be good.

[0050] The content of the aromatic group-containing monofunctional monomer is preferably 20 to 50 mass %, more preferably 25 to 45 mass %, and further preferably 28 to 40 mass %, based on the total amount of the polymerizable compounds. When the content of the aromatic group-containing monofunctional monomer is within the above range, the adhesion and abrasion resistance of the coating film tend to be further improved.

[0051] 1.6.1.2.3. Nitrogen-containing monofunctional monomers The nitrogen-containing monofunctional monomer is not particularly limited, and examples thereof include nitrogen-containing monofunctional vinyl monomers such as N-vinylcaprolactam, N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, and N-vinylpyrrolidone; nitrogen-containing monofunctional acrylate monomers such as acryloylmorpholine; and nitrogen-containing monofunctional acrylamide monomers such as (meth)acrylamide, N-hydroxymethyl(meth)acrylamide, diacetone acrylamide, N,N-dimethyl(meth)acrylamide, and dimethylaminoethyl acrylate benzyl chloride quaternary salt.

[0052] Among these, monomers having a nitrogen-containing heterocyclic structure such as N-vinylcaprolactam, N-vinylcarbazole, N-vinylpyrrolidone, or acryloylmorpholine are more preferred, and acryloylmorpholine (ACMO) is even more preferred. By using such nitrogen-containing monofunctional monomers, the abrasion resistance of the coating film tends to be further improved. Furthermore, nitrogen-containing monofunctional acrylate monomers having a nitrogen-containing heterocyclic structure such as acryloylmorpholine tend to further improve the stretchability and adhesion of the coating film.

[0053] The content of the nitrogen-containing monofunctional monomer is preferably 10 to 25 mass %, more preferably 12.5 to 22.5 mass %, and even more preferably 15 to 20 mass %, based on the total amount of the polymerizable compounds. When the content of the nitrogen-containing monofunctional monomer is within the above range, the abrasion resistance and adhesion of the coating film tend to be further improved.

[0054] 1.6.1.3. Multifunctional monomers The polyfunctional monomer is not particularly limited, but examples thereof include vinyl group-containing (meth)acrylates and polyfunctional (meth)acrylates.

[0055] 1.6.1.3.1. Vinyl-containing (meth)acrylates The vinyl group-containing (meth)acrylate is not particularly limited, but examples thereof include compounds represented by formula (1). H2C=CR 1 -CO-OR 2 -O-CH=CH-R 3 ... (1) (In the formula, R 1 is a hydrogen atom or a methyl group, R 2 is a divalent organic residue having 2 to 20 carbon atoms, and R 3 is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms.

[0056] In the above formula (1), R 2 Examples of the divalent organic residue having 2 to 20 carbon atoms and represented by the formula (I) include a linear, branched or cyclic alkylene group having 2 to 20 carbon atoms which may be substituted, an alkylene group having 2 to 20 carbon atoms which has an oxygen atom due to an ether bond and / or an ester bond in the structure which may be substituted, and a divalent aromatic group having 6 to 11 carbon atoms which may be substituted.

[0057] Among these, alkylene groups having 2 to 6 carbon atoms, such as ethylene group, n-propylene group, isopropylene group, and butylene group, and alkylene groups having 2 to 9 carbon atoms and an oxygen atom due to an ether bond in the structure, such as oxyethylene group, oxy n-propylene group, oxyisopropylene group, and oxybutylene group, are preferred. Furthermore, from the viewpoint of further reducing the viscosity of the composition and further improving the curability of the composition, R 2 is an alkylene group having 2 to 9 carbon atoms and having an oxygen atom by an ether bond in the structure, such as an oxyethylene group, an oxyn-propylene group, an oxyisopropylene group, or an oxybutylene group, is more preferred.

[0058] In the above formula (1), R 3 The monovalent organic residue having 1 to 11 carbon atoms and represented by the formula (I) is preferably a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may be substituted, or an aromatic group having 6 to 11 carbon atoms which may be substituted.

[0059] Among these, alkyl groups having 1 to 2 carbon atoms, such as a methyl group or an ethyl group, and aromatic groups having 6 to 8 carbon atoms, such as a phenyl group and a benzyl group, are preferably used.

[0060] Specific examples of the compound of formula (1) include, but are not limited to, 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, with 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA) being preferred.

[0061] In particular, it is preferable that the second ink contains a vinyl group-containing (meth)acrylate represented by the above formula (1) as a polyfunctional monomer, which tends to further improve the curability of the second ink.

[0062] The content of the vinyl group-containing (meth)acrylate is preferably 1 to 25 mass %, more preferably 2 to 20 mass %, and further preferably 3 to 15 mass %, based on the total amount of the polymerizable compounds. When the content of the nitrogen-containing monofunctional monomer is within the above range, the viscosity of the ink tends to decrease and the ejection stability tends to be improved.

[0063] 1.6.1.3.2 Multifunctional (meth)acrylates The polyfunctional (meth)acrylate is not particularly limited, and examples thereof include bifunctional (meth)acrylates such as dipropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and triethylene glycol di(meth)acrylate; and trifunctional or higher polyfunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate.

[0064] Among these, dipropylene glycol diacrylate (DPGDA) is preferable. By using such a polyfunctional (meth)acrylate, the curing property and abrasion resistance of the ink tend to be further improved.

[0065] The content of the polyfunctional (meth)acrylate is preferably 1.0 to 10 mass% or more, more preferably 2.0 to 8.0 mass%, and even more preferably 3.0 to 7.0 mass%, based on the total amount of the polymerizable compounds. By having the content of the polyfunctional (meth)acrylate within the above range, the curability and abrasion resistance of the ink tend to be further improved.

[0066] 1.6.2. Photoinitiators The photopolymerization initiator is not particularly limited as long as it generates active species by irradiation with radiation, and examples thereof include known photopolymerization initiators such as acylphosphine oxide-based photopolymerization initiators, alkylphenone-based polymerization initiators, titanocene-based polymerization initiators, and thioxanthone-based photopolymerization initiators. Among these, acylphosphine oxide-based photopolymerization initiators are preferred. By using such a photopolymerization initiator, the curability of the ink is improved, and in particular, the curability by the curing process using UV-LED light tends to be improved. The photopolymerization initiator may be used alone or in combination of two or more types.

[0067] The acylphosphine oxide photopolymerization initiator is not particularly limited, but examples thereof include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and the like.

[0068] Commercially available products of such acylphosphine oxide photopolymerization initiators include, for example, IRGACURE 819 (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide), IRGACURE 1800 (a mixture of bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 1-hydroxy-cyclohexyl-phenyl ketone in a mass ratio of 25:75), and IRGACURE TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide) (all manufactured by BASF).

[0069] The content of the photopolymerization initiator is preferably 3.0 to 15 mass % relative to the total amount of the ink, more preferably 5.0 to 13.5 mass %, and even more preferably 8.0 to 12 mass %. When the content of the photopolymerization initiator is within the above range, the curability of the ink and the solubility of the photopolymerization initiator tend to be further improved.

[0070] 1.6.3. Polymerization inhibitors Examples of the polymerization inhibitor include, but are not limited to, p-methoxyphenol, hydroquinone monomethyl ether (MEHQ), 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, hydroquinone, cresol, t-butylcatechol, 3,5-di-t-butyl-4-hydroxytoluene, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-butylphenol), and 4,4'-thiobis(3-methyl-6-t-butylphenol), hindered amine compounds, etc. The polymerization inhibitor may be used alone or in combination of two or more.

[0071] The content of the polymerization inhibitor is preferably 0.05 to 1.0 mass %, and more preferably 0.05 to 0.5 mass %, relative to the total amount of the ink.

[0072] 1.6.4. Slip agents The slip agent is preferably a silicone surfactant, more preferably a polyester-modified silicone or a polyether-modified silicone. Examples of the polyester-modified silicone include BYK-347, 348, BYK-UV3500, 3510, and 3530 (all manufactured by BYK Additives & Instruments), and examples of the polyether-modified silicone include BYK-3570 (manufactured by BYK Additives & Instruments). The slip agent may be used alone or in combination of two or more.

[0073] The content of the slip agent is preferably 0.01 to 2.0% by mass, and more preferably 0.05 to 1.0% by mass, based on the total amount of the ink.

[0074] Colorants The coloring material may be at least one of a pigment and a dye.

[0075] In the case of color inks, the total content of color materials is preferably 0.2 to 20% by mass, more preferably 0.5 to 15% by mass, and even more preferably 1.0 to 10% by mass, relative to the total amount of ink. As described above, in the case of clear inks, it is preferable that no color materials are contained, and even if they are unavoidably contained, the content is less than 0.2% by mass.

[0076] Dispersants The dispersant is not particularly limited, but may be, for example, a dispersant commonly used for preparing a pigment dispersion, such as a polymer dispersant. Specific examples thereof include polyoxyalkylene polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, sulfur-containing polymers, fluorine-containing polymers, and epoxy resins as the main component. The dispersant may be used alone or in combination of two or more.

[0077] Commercially available polymer dispersants include the Ajisper series manufactured by Ajinomoto Fine-Techno Co., Ltd., the Solsperse series (Solsperse 36000, etc.) available from Avecia and Noveon, the Disperbyk series manufactured by BYK Additives & Instruments, and the Disparlon series manufactured by Kusumoto Chemicals Co., Ltd.

[0078] The content of the dispersant is preferably 0.1 to 2.0% by mass, more preferably 0.1 to 1.0% by mass, and even more preferably 0.1 to 0.5% by mass, relative to the total amount of the ink.

[0079] 2. Recordings Fig. 2 is a schematic cross-sectional view of a recorded matter 5 in this embodiment. As shown in Fig. 2, a recorded matter 7 in this embodiment is composed of a recording medium 6 having a recorded surface 61 to which a first ink 71 and a second ink 72 are attached and a non-recorded surface 62 to which neither the first ink 71 nor the second ink 72 is attached, the first ink 71 being attached to the recorded surface 61 of the recording medium 6, and the second ink 72 being further attached to the first ink 71 with a relatively low duty.

[0080] For example, by applying a first ink 71, which is a color ink, as a solid image or the like, and then applying a second ink 72, which is a clear ink, with a low duty, the peelability between the recording surface 61 having the image formed with the first ink 71 and the non-recording surface 62 is improved, and it is possible to prevent marks from being left on the recording surface 61 or part of the first ink 71 or second ink 72 from adhering to the non-recording surface 62.

[0081] The recording medium 6 used in the recorded matter 7 in this embodiment is long as shown in Fig. 1, and the recorded matter 7 is preferably stored as a roll wound around a roller. By storing in this state, the recorded surface 61 and the non-recorded surface 62 of the recorded matter 7 come into contact, but the contact area between the recorded surface 61 and the non-recorded surface 62 is reduced by the second ink 72. Therefore, when the recorded matter 7 is used as a label or the like, it is possible to prevent marks from being left on the recorded surface 61 and to prevent a part of the first ink 71 or the second ink 72 from adhering to the non-recorded surface 62 even when the recorded matter 7 is unwound from the roll.

[0082] In particular, when a large amount of monofunctional monomer is used in the first ink 71 from the viewpoint of improving the adhesion and followability of the image layer formed by the first ink 71 to the recording medium 6, the adhesion between the recorded surface 61 and the non-recorded surface 62 also improves, which is likely to cause problems such as leaving marks or peeling. However, with the recorded matter 7 of this embodiment, the second ink 72 can reduce the adhesion between the recorded surface 61 and the non-recorded surface 62, so that leaving marks and peeling can be suppressed. EXAMPLES

[0083] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0084] 1. Preparation of Inkjet Composition First, the colorant, dispersant, and a portion of each monomer were weighed and placed in a tank for pigment dispersion. A ceramic bead mill with a diameter of 1 mm was then placed in the tank and stirred to obtain a pigment dispersion in which the colorant was dispersed in the monomer.

[0085] Next, the remaining monomers, polymerization initiator, and polymerization inhibitor were placed in a stainless steel container, a mixing tank, and mixed and stirred to completely dissolve, so as to obtain the composition shown in Table 1. The pigment dispersion obtained above was then added, and further mixed and stirred at room temperature for 1 hour, and then filtered through a 5 μm membrane filter to obtain a radiation-curable inkjet composition for each example. The numerical values ​​of each component shown in each example in the table represent mass % unless otherwise specified.

[0086] [Table 1]

[0087] <Monofunctional monomer> ACMO (Acryloylmorpholine, manufactured by KJ Chemicals Co., Ltd.) PEA (product name "Viscoat #192, manufactured by Osaka Organic Chemical Industry Co., Ltd., phenoxyethyl acrylate") DCPA (Hitachi Chemical, dicyclopentenyl acrylate) IBXA (Osaka Organic Chemical Industry, Ltd., isobornyl acrylate) <Polyfunctional Monomer> · VEEA (2-(2-vinyloxyethoxy)ethyl acrylate, manufactured by Nippon Shokubai Co., Ltd.) DPGDA (product name "SR508", Sartomer Corporation, dipropylene glycol diacrylate) <Polymerization initiator> 819 (product name "IRGACURE 819" manufactured by BASF, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide) TPO (product name "IRGACURE TPO", manufactured by BASF, 2,4,6-trimethylbenzoyldiphenylphosphine oxide) <Polymerization inhibitor> MEHQ (product name "p-methoxyphenol", manufactured by Kanto Chemical Co., Ltd., hydroquinone monomethyl ether) <Slip agent> BYK-UV3500 (BYK Additives & Instruments, polyether-modified polydimethylsiloxane with acryloyl groups) <Coloring material (pigment)> PB15:3 (product name "CI Pigment Blue 15:3", manufactured by DIC, Phthalocyanine Blue) PW6 (product name "CI Pigment White 6", manufactured by Tika, titanium oxide) <Dispersant> Solsperse 36000 (Lubrizol, polymer dispersant)

[0088] In Table 1, "content of monofunctional monomer relative to total amount of polymerizable compounds" represents the ratio (mass %) of the content of monofunctional monomer relative to the total amount of polymerizable compounds.

[0089] 2. Evaluation method 2.1.Adhesion Using a printer equipped with an LED (modified model PX-G5000, manufactured by Seiko Epson Corporation), each radiation-curable inkjet composition listed in Table 1 was discharged onto a vinyl chloride film (JT5829R, manufactured by MACtac) at 20 ng / dot and 600 dpi x 600 dpi, and cured to obtain a coating film with a thickness of 10 μm. An incision was made in the obtained coating film, a transparent adhesive tape was attached to the incision, and the tape was rubbed with a finger sufficiently so that the coating film could be seen through. Next, within 5 minutes after the tape was attached, the tape was peeled off from the coating film at an angle close to 60° in 0.5 to 1.0 seconds. Based on the presence or absence of peeling of the coating film from the vinyl chloride film at this time, the adhesion was evaluated according to the following evaluation criteria. (Evaluation Criteria) A: No peeling was observed. B: Partial peeling was observed. C: Completely peeled off.

[0090] 2.2. Curability Using a printer equipped with an LED (modified PX-G5000 model, manufactured by Seiko Epson Corporation), each radiation-curable inkjet composition listed in Table 1 was applied to a polyvinyl chloride film (JT5829R, manufactured by MACtac) to a coating thickness of 10 μm. The inkjet compositions were then exposed to a central wavelength of 395 nm and a 1000 mW / cm 2 The coating surface was rubbed with a cotton swab, and the curing property was evaluated based on the irradiation energy at which the cotton swab did not become colored. 2 ] is the irradiation intensity [mW / cm 2 The evaluation criteria are as follows: (Evaluation Criteria) A: Irradiation energy is 200mJ / cm 2 below B: Irradiation energy is 200 mJ / cm 2 Excess 300mJ / cm 2 below C: Irradiation energy is 300 mJ / cm 2 excess

[0091] 2.3. Traces Using a printer equipped with an LED (modified PX-G5000, manufactured by Seiko Epson Corporation), each radiation-curable inkjet composition was applied onto a polyvinyl chloride film (JT5829R, manufactured by MACtac) in the combinations shown in Table 2. At this time, the first ink, which was the lower layer, was a solid image of 20 ng / dot, 600 dpi x 600 dpi, and duty 100%, and irradiation energy after application of the first ink was 400 mJ / cm. 2 The second ink, which is the upper layer, was applied on top of the first ink coating, and the application conditions were 20 ng / dot, 600 dpi x 600 dpi, and the duty was as shown in Table 2. The second ink was also applied with an irradiation energy of 400 mJ / cm after the application of the second ink. 2 A recorded matter was obtained by irradiating ultraviolet rays so as to obtain a recorded matter. Note that only in Comparative Example 1, the second ink, which is to be the upper layer, was not attached, and the evaluation described below was carried out.

[0092] On the recorded surface of the recorded matter obtained as described above, on which the first ink and the second ink were attached, another vinyl chloride film on which no recording was made was placed, and a load of 1 kg was applied from above and maintained for 10 minutes. After that, the recorded matter was peeled off from the other vinyl chloride film, and it was visually confirmed whether or not traces of the other vinyl chloride film were transferred to the recorded surface. The evaluation criteria were as follows. (Evaluation Criteria) A: No transfer marks on the recording surface B: There are very slight transfer marks on the recording surface. C: There are noticeable transfer marks on the recording surface. D: There are noticeable transfer marks on the recording surface, and color transfer to the backside of other vinyl chloride films.

[0093] 2.4. Glossiness A recorded matter was obtained in the same manner as in the case of the above-mentioned traces. The obtained printed matter was visually observed to see how far away from the coating film the reflection of the fluorescent light could be visually confirmed. The evaluation criteria were as follows. (Evaluation Criteria) A:Can be seen from a distance of more than 50cm B: If it is between 30cm and 50cm, it can be confirmed. C: If it was less than 30cm, it could be confirmed.

[0094] [Table 2]

[0095] 3. Evaluation results The conditions for the recording method using each radiation curable inkjet composition and the evaluation results are shown in Table 2. It can be seen from Table 2 that by applying the second ink at a specified duty, minimal traces are left behind and the image quality (glossiness) of the first ink is maintained.

Claims

1. a first ejection step of ejecting a first ink, which is a radiation curable ink jet composition, onto a recording medium; a first irradiation step of irradiating the first ink attached to the recording medium with radiation to obtain a cured coating film of the first ink; a second ejection step of ejecting a second ink, which is a radiation curable ink jet composition, onto a cured coating film of the first ink so that the duty is 5% or more and 20% or less; a second irradiation step of irradiating the second ink attached to the recording medium with radiation to cure the second ink, thereby obtaining a recorded matter; a lamination process of stacking the recorded matter such that a recorded surface to which the first ink and the second ink are applied faces a non-recorded surface to which the first ink and the second ink are not applied, A method for producing a recorded matter (excluding the second ink containing 50% by mass or more of a polyfunctional polymerizable compound in the polymerizable compound).

2. The first ink is a color ink. A method for producing the recorded matter according to claim 1.

3. The second ink is a clear ink. A method for producing the recorded matter according to claim 1 or 2.

4. In the stacking step, the recorded matter is wound into a roll so that the recorded surface and the non-recorded surface face each other. A method for producing the recorded matter according to any one of claims 1 to 3.

5. The recording surface and the non-recording surface of the recording medium are both non-absorbent. A method for producing the recorded matter according to any one of claims 1 to 4.

6. the first ink contains a polymerizable compound containing a monofunctional monomer, The content of the monofunctional monomer is 80 mass% or more based on the total amount of the polymerizable compound. A method for producing the recorded matter according to any one of claims 1 to 5.

7. the second ink contains a polymerizable compound containing a polyfunctional monomer, The polyfunctional monomer contains a vinyl group-containing (meth)acrylate represented by the following formula (1): H 2 C=CR 1 -CO-OR 2 -O-CH=CH-R 3 ・・・ (1) (In the formula, R 1 is a hydrogen atom or a methyl group, R 2 is a divalent organic residue having 2 to 20 carbon atoms, R 3 is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. A method for producing the recorded matter according to any one of claims 1 to 6.

8. the polymerizable compound contained in the second ink contains a monofunctional monomer, The content of the monofunctional monomer is 80 mass% or more based on the total amount of the polymerizable compound. A method for producing the recorded matter according to claim 7.

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