Manufacturing methods for printed materials

Abstract

To provide a method for producing a printed matter in which components in an active ray curable ink hardly adhere to conveying means.SOLUTION: There is provided a method for producing a printed matter which comprises: a step of coating a first surface of a recording medium with an active ray curable ink to form a first coating film; a step of irradiating the first coating film on the recording medium with an active ray to cure the first coating film; and a step of conveying the recording medium, wherein the active ray curable ink contains an active ray curable compound, a gelling agent having a specific structure and a coloring material. In the step of conveying the recording medium, a cured product of the first coating film and conveying means of an image formation apparatus come into contact with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing printed materials. [Background technology]

[0002] Various printing methods are known for forming images on various recording media. Among them, inkjet printing is widely used because it allows for on-demand printing. One type of inkjet printing is a printing method that applies active-ray curing ink, which hardens when exposed to active light.

[0003] The active light-curable ink in question generally contains an active light-curable compound and a photoinitiator, and hardens upon irradiation with active light. Therefore, it is possible to form images on recording media that do not absorb ink, and hardening can be achieved in a short time. For this reason, image forming apparatuses with a configuration in which the formed image and the transport means come into contact are also known (for example, reference 1). In particular, when forming images on both sides of a recording medium, it is necessary to form an image on one side of the recording medium, then invert the recording medium and perform further image formation. Therefore, in image forming apparatuses that perform double-sided printing, there are often many opportunities for the image and the transport means to come into contact. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-138654 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, after diligent investigation by the inventors, it was confirmed that, depending on the type of active light-curable ink, if the formed image comes into contact with the transport means of the image forming apparatus, some components may adhere to the transport means.

[0006] Recently, active light-curable inks have been developed that contain an active light-curable compound and a gelling agent, and undergo a reversible sol-gel phase transition depending on temperature. In high-temperature environments, this active light-curable ink becomes a sol and has sufficient fluidity. On the other hand, in low-temperature environments, the ink becomes a gel and its fluidity decreases. Therefore, it exhibits good pinning properties on recording media, making it easy to obtain high-resolution images. However, depending on the type of gelling agent in the active light-curable ink, the gelling agent may precipitate on the surface of the cured product. As a result, when the formed image (cured product of the active light-curable ink) comes into contact with the transport means, the gelling agent may adhere to the transport means.

[0007] If components from the ink adhere to the transport mechanism, it can lead to soiling of the printed material or cause problems with the transport of the printed material. Furthermore, if components from the ink (such as gelling agents) adhere to the transport mechanism, it can result in the desired texture or even prevent the production of the desired printed material (image).

[0008] This invention was made in view of the above problems. The objective is to provide a method for producing high-quality printed materials in which components in an active light-curable ink are less likely to adhere to the transport means. [Means for solving the problem]

[0009] One embodiment of the present invention provides a method for manufacturing a printed material, comprising the steps of: applying an active light-curable ink to the first surface of a recording medium and curing it to form a first image; and transporting the recording medium on which the first image has been formed, wherein the active light-curable ink comprises one or more active light-curable compounds, a gelling agent containing a ketone compound represented by general formula (1) and / or an ester compound represented by general formula (2), and a colorant, and in the step of transporting the recording medium, the first image comes into contact with the transport means of an image forming apparatus. R 1 -C(=O)-R 2 (1) (R 1 and R2 each independently represents a hydrocarbon group containing a linear structure having 10 to 16 carbon atoms) R 3 -COO-R 4 (2) (R 3 and R 4 each independently represents a hydrocarbon group containing a linear structure having 12 to 18 carbon atoms) Effects of the Invention

[0010] According to the method for producing a printed matter of the present invention, components in the actinic ray curable ink hardly adhere to the conveying means, and a high-quality printed matter can be produced. Brief Description of Drawings

[0011] [Figure 1] FIG. 1 is a front view of the internal structure of an image forming apparatus used in the method for producing a printed matter according to one embodiment. [Figure 2] FIG. 2 is a front view of the internal structure of an image forming apparatus used in the method for producing a printed matter according to one embodiment. Mode for Carrying Out the Invention

[0012] Hereinafter, one embodiment of the present invention will be described in detail. However, the present invention is not limited to this embodiment.

[0013] A method for producing a printed matter according to one embodiment of the present invention includes the steps of: applying an actinic ray curable ink (hereinafter, also simply referred to as "ink") to a first surface of a recording medium and curing the ink to form a first image; and conveying the recording medium on which the first image has been formed. The method for producing a printed matter may be a method for forming an image only on one surface of a recording medium, or may be a method for forming images on both surfaces of a recording medium.

[0014] Figures 1 and 2 show front views of the internal structure of the image forming apparatus 100 used for manufacturing the printed material. However, the configuration of the image forming apparatus 100 is an example, and the image forming apparatus used for manufacturing the printed material according to this embodiment is not limited to this configuration.

[0015] Figure 1 shows the movement path of the recording medium 1 when an image is formed on only one side of the recording medium 1 (single-sided printing), indicated by arrows. In the image forming apparatus 100, first, the recording medium 1 supplied from the recording medium supply means 10 is moved to the vicinity of the coating means 20 by the first transport means 110 (feed roller 111 and support roller 112). Then, the coating means 20 applies ink to a desired area on the first surface of the recording medium 1. The coating means 20 may apply multiple types (e.g., multiple colors) of ink. After that, the recording medium 1 is moved to the vicinity of the curing means 30 by the first transport means 110 (rotation of the support roller 112, etc.). Then, the ink applied by the coating means 20 is cured (here, the ink is cured by irradiation with active light) to form the first image. The recording medium 1 is transported by the second transport means 120 (transport rollers 121 and 122) and discharged to the outside of the image forming apparatus 100. In this method, the first image comes into contact with the second conveying means (conveyor roller 121).

[0016] Figure 2 shows the movement path of the recording medium 1 when an image is formed on both sides of the recording medium 1 (double-sided printing), indicated by arrows. In Figure 2, the movement path of the recording medium 1 from when an image (first image) is formed on the first side until the recording medium 1 is inverted is shown by a solid line. The movement path of the recording medium 1 after it has been inverted is shown by a dashed line. In the image forming apparatus 100, first, the recording medium 1 supplied from the recording medium supply means 10 is moved to the vicinity of the coating means 20 by the first transport means 110 (here, the paper feed roller 111 and the support roller 112). Then, the coating means 20 applies ink to a desired area on the first side of the recording medium 1. The coating means 20 may apply multiple types (multiple colors) of ink. After that, the recording medium 1 is moved to the vicinity of the curing means 30 by the first transport means 110 (rotation of the support roller 112, etc.). Then, the ink applied by the coating means 20 is cured (in this case, the ink is cured by irradiating it with active light) to form the first image.

[0017] Subsequently, the recording medium 1 is transported by the third transport means (reversing roller) 130 to reverse the orientation of the recording medium 1. Then, the recording medium 1 is transported again by the first transport means 110 (in this case, the support roller 102), and the coating means 20 and curing means 120 form a second image. Then, the recording medium 1 is transported by the second transport means 120 (transport rollers 121 and 122) and discharged to the outside of the image forming apparatus 100. In this method, the formed first image comes into contact with the first transport means 110 (support roller 112), the second transport means 120 (transport roller 122), and the third transport means (reversing roller) 130, respectively. Furthermore, the second image comes into contact with the second transport means 120 (transport roller 121).

[0018] Thus, when the first and second images (hereinafter, when there is no need to distinguish between them, they will be collectively referred to as "images") formed on the recording medium come into contact with the transport means, if there are uncured components or gelling agents precipitated on the surface of the image, these uncured components and gelling agents are likely to adhere to the transport means. As a result, when performing continuous printing, this may cause contamination of subsequent recording media or make it difficult to transport the recording media. Furthermore, the adhesion of components in the image to the transport means may change the surface state of the image, making it difficult to obtain the desired texture or high-quality printed materials.

[0019] In contrast, the printing method of this embodiment uses an ink that contains an active light-curable compound, a gelling agent containing a ketone compound or an ester compound having a linear structure, and a colorant, and undergoes a reversible sol-gel phase transition depending on the temperature. The linear structure of the gelling agent is shorter than that of the gelling agents contained in conventional inks. Therefore, when the ink gels, the gelling agent moves easily within the ink and aggregates in a short time. As a result, the amount of free gelling agent is very small, and the gelling agent is less likely to precipitate on the surface of the coating film. Therefore, in the printing method using this ink, even if the first or second image on the recording medium comes into contact with the transport means of the image forming apparatus, the gelling agent is less likely to adhere to the transport means, and high-quality printed materials can be obtained. Furthermore, even when continuous printing is performed, subsequent recording media and printed materials are less likely to become soiled, and transport failures within the image forming apparatus are less likely to occur.

[0020] Furthermore, when manufacturing printed materials, an overcoat layer is sometimes formed on the image to adjust the texture of the image surface or to protect the image. However, if a large amount of gelling agent components precipitate on the image surface, the adhesion between the ink and the overcoat layer tends to be poor. In contrast, the printing method of this embodiment has the advantage that the gelling agent is less likely to precipitate on the image surface, resulting in good adhesion when an overcoat layer is formed.

[0021] Furthermore, generally, when double-sided printing is performed using light-curable ink, the resulting printed material may warp depending on the type of recording medium. This is thought to be because, if the recording medium is transparent to light, and the first image is formed on the first surface of the recording medium before the second image is formed on the second surface, the first image is irradiated with light twice (from both the first and second surfaces). For example, if there is a difference in the curing state between the first and second images, the printed material is thought to warp due to curing shrinkage of the first image, etc. In contrast, in the printing method of this embodiment, gelling agent crystals are included inside the first and second images. Therefore, these crystals relieve the above-mentioned stress and suppress the warping of the printed material.

[0022] The ink used in this embodiment will be described first, followed by a description of the image formation method and image forming apparatus.

[0023] (1) Light-curing ink As described above, the ink used in this embodiment only needs to contain an active light-curable compound, a gelling agent, and a colorant, and usually further contains a photoinitiator. The ink may also contain other components as needed.

[0024] (Active light curable compound) The active light-curable compound can be any compound that crosslinks or polymerizes upon irradiation with active light. Examples of active light in this specification include electron beams, ultraviolet rays, alpha rays, gamma rays, and X-rays. Here, the active light-curable compound may be either a radical polymerizable compound or a cationic polymerizable compound, but a radical polymerizable compound is more preferred.

[0025] The radical polymerizable compound may be any compound having an ethylenically unsaturated bond that is capable of radical polymerization, and may be a monomer, oligomer, or polymer, or a mixture thereof. The ink may contain only one radical polymerizable compound, or two or more.

[0026] Examples of radical polymerizable compounds include unsaturated carboxylic acids and their salts, unsaturated carboxylic acid ester compounds, unsaturated carboxylic acid urethane compounds, unsaturated carboxylic acid amide compounds and their anhydrides, acrylonitrile, styrene, unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes. Among these, unsaturated carboxylic acid ester compounds are preferred from the viewpoint of reactivity and versatility, and (meth)acrylate compounds are more preferred. In this specification, "(meth)acrylate" refers to either "acrylate" or "methacrylate," or both, and "(meth)acrylic" refers to either "acrylic" or "methacrylic," or both.

[0027] Examples of (meth)acrylate compounds include octadecyl (meth)acrylate, isoamyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, isomirsutyl (meth)acrylate, isostearyl (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate. Monofunctional monomers such as meth)acrylate, methoxypropylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, t-butylcyclohexyl (meth)acrylate, and methyl (5-ethyl-1,3-dioxan-5-yl)acrylate; Triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, neopentyl glycol propoxylate di(meth)acrylate Difunctional monomers such as acrylate, 1,10-decanediol diacrylate, dimethylol-tricyclodecane di(meth)acrylate, bisphenol A PO adduct di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, polyethylene glycol diacrylate, tripropylene glycol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, dipropylene diglycol di(meth)acrylate, polyethylene di(meth)acrylate, etc. This includes polyfunctional monomers with three or more functions, such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxytri(meth)acrylate, and pentaerythritol ethoxytetra(meth)acrylate.

[0028] From the viewpoint of photosensitivity and other factors, preferred (meth)acrylate compounds include methyl (5-ethyl-1,3-dioxan-5-yl)acrylate, neopentyl glycol di(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, neopentyl glycol(meth)acrylate hydroxypivalate, octadecyl(meth)acrylate, neopentyl glycol propoxylate di(meth)acrylate, 1,10-decanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and 1,9-nonanediol di(meth)acrylate.

[0029] (Meth)acrylate compounds may be modified compounds. Examples of modified compounds include ethylene oxide-modified or propylene oxide-modified (meth)acrylate compounds such as ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, and ethylene oxide-modified pentaerythritol tetraacrylate; caprolactone-modified (meth)acrylate compounds such as caprolactone-modified trimethylolpropane tri(meth)acrylate; and caprolactam-modified (meth)acrylate compounds such as caprolactam-modified dipentaerythritol hexa(meth)acrylate.

[0030] (Meth)acrylate compounds may also be polymerizable oligomers. Examples of polymerizable oligomers include epoxy (meth)acrylate oligomers, aliphatic urethane (meth)acrylate oligomers, aromatic urethane (meth)acrylate oligomers, polyester (meth)acrylate oligomers, and linear (meth)acrylic oligomers.

[0031] On the other hand, examples of cationic polymerizable compounds include epoxy compounds, vinyl ether compounds, and oxetane compounds. The ink may contain only one cationic polymerizable compound, or it may contain two or more.

[0032] The epoxy compound may be an aromatic epoxide, an alicyclic epoxide, or an aliphatic epoxide, and aromatic epoxides and alicyclic epoxides are preferred to enhance curability.

[0033] Examples of aromatic epoxides include di- or polyglycidyl ethers obtained by reacting polyhydric phenols or their alkylene oxide adducts with epichlorohydrin. Examples of polyhydric phenols or their alkylene oxide adducts to be reacted include bisphenol A or its alkylene oxide adduct. Examples of alkylene oxides in alkylene oxide adducts include ethylene oxide and propylene oxide.

[0034] Examples of alicyclic epoxides include cycloalkane oxide-containing compounds obtained by epoxidizing cycloalkane-containing compounds with oxidizing agents such as hydrogen peroxide or peracids. Examples of cycloalkanes in cycloalkane oxide-containing compounds include cyclohexene or cyclopentene.

[0035] Examples of aliphatic epoxides include di or polyglycidyl ethers obtained by reacting aliphatic polyhydric alcohols or their alkylene oxide adducts with epichlorohydrin. Examples of aliphatic polyhydric alcohols include ethylene glycol, propylene glycol, and alkylene glycols such as 1,6-hexanediol. Examples of alkylene oxides in alkylene oxide adducts include ethylene oxide and propylene oxide.

[0036] Examples of vinyl ether compounds include monovinyl ether compounds such as ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, 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; This includes di- or tri-vinyl ether compounds such as ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, and trimethylolpropane trivinyl ether. Of these vinyl ether compounds, di- or tri-vinyl ether compounds are preferred when considering curability and adhesion.

[0037] The oxetane compound can be any compound having an oxetane ring, and examples include the oxetane compounds described in Japanese Patent Publication No. 2001-220526, Japanese Patent Publication No. 2001-310937, and Japanese Patent Publication No. 2005-255821.

[0038] Here, the SP value of the entire active light ray-curable compound described above is preferably 16.8 or more and 18.5 or less, and more preferably 17.3 or more and 17.8 or less. The SP value of the entire active light ray-curable compound refers to the SP value of the active light ray-curable compound when the ink contains only one type of active light ray-curable compound. On the other hand, when the ink contains a plurality of types of active light ray-curable compounds, it refers to the SP value of a composition obtained by mixing these compounds at the same ratio as that in the ink. When the SP value of the entire active light ray-curable compound falls within the above range, the compatibility between the gelling agent described later and the active light ray-curable composition is improved. Further, when the SP value of the entire active light ray-curable compound falls within the above range, in the case of forming an overcoat layer on an image, the affinity between the component on the image surface (the cured product of the active light ray-curable compound) and the overcoat layer tends to be better, and the adhesion between these tends to be enhanced.

[0039] For the SP value of an active light ray-curable compound, a value calculated by inputting the structure of each compound into software (software name: Hansen Solubility Parameter in Practice (HSPiP)) can be adopted. When the active light ray-curable compound is a combination of two or more (n types) of compounds, the SP value of the entire active light ray-curable compound is calculated from the volume fraction φ of each of the n types of active light ray-curable compounds k and each SP value δ k by substituting into the following formula.

Chemical Formula

[0040] The total amount of the active light ray-curable compound in the ink is preferably 1% by mass or more and 97% by mass or less, and more preferably 30% by mass or more and 95% by mass or less. When the content of the active light ray-curable compound falls within the above range, the adhesion between the recording medium and the image tends to be enhanced. Further, since the amounts of the coloring material and the gelling agent are relatively sufficient, an image having a desired color and texture is easily obtained.

[0041] (Gelling Agent) The gelling agent may contain either a ketone compound represented by general formula (1) or an ester compound represented by general formula (2), or both, and it is particularly preferable to contain an ester compound represented by general formula (2). The ink may contain only one type of gelling agent, or it may contain two or more types.

[0042] R 1 -C(=O)-R 2 (1) In the above general formula (1), R 1 and R 2 Each of these independently represents a hydrocarbon group containing a linear structure with 10 to 16 carbon atoms. 1 and R 2 They may be the same or they may be different.

[0043] Examples of ketone compounds represented by general formula (1) include 12-tricosanone (11-11 carbon atoms), 14-heptacosanone (13-13 carbon atoms), henthriacontan-16-one (15-15 carbon atoms), 13-heptacosanone (12-14 carbon atoms), 13-nonacosanone (12-16 carbon atoms), 15-henthriacontanone (14-16 carbon atoms), etc. Note that the carbon atoms in parentheses above represent the two R groups separated by the carbonyl group. 1 , R 2 This represents the number of carbon atoms in each linear portion.

[0044] R 3 -COO-R 4 (2) In general formula (2), R 3 and R 4 Each of these independently represents a hydrocarbon group containing a linear structure with 12 to 18 carbon atoms, and the number of carbon atoms in the linear structure is more preferably 15 to 18.

[0045] Examples of ester compounds represented by general formula (2) include stearyl stearate (17-18 carbon atoms), palmityl stearate (17-16 carbon atoms), lauryl stearate (17-12 carbon atoms), cetyl palmitate (15-16 carbon atoms), stearyl palmitate (15-18 carbon atoms), myristyl myristate (13-14 carbon atoms), cetyl myristate (13-16 carbon atoms), stearyl oleate (17-18 carbon atoms), stearyl linoleate (17-18 carbon atoms), isostearyl palmitate (15-18 carbon atoms), etc. Note that the carbon numbers in parentheses above refer to the two R groups separated by the ester group. 3 , R 4 This represents the number of carbon atoms in each linear portion.

[0046] Furthermore, it is preferable that the SP value distance R between the SP value of the entire active photocurable compound and the SP value of the gelling agent, as represented by the following formula (1), is 2 or more and 5.5 or less. R = {4 * (dDm - dDg)} 2 +(dPm-dPg) 2 +(dHm-dHg) 2} 0.5 ...Equation (1) (In equation (1), dDm represents the dispersion term of the total evaporation energy of the active photocurable compound. dPm represents the polarization term of the total evaporation energy of the active photocurable compound. dHm represents the hydrogen bonding term of the total evaporation energy of the active photocurable compound. dDg represents the dispersion term of the evaporation energy of the gelling agent. dPg represents the polarization term of the evaporation energy of the gelling agent. dHg represents the hydrogen bonding term in the evaporation energy of the gelling agent.

[0047] The dispersion term dD, polarization term dP, and hydrogen bonding term dH of the above evaporation energy are material-specific values, and many specific values ​​are already described in publicly available literature 1 (HANSEN SOLUBILITY PARAMETERS A User's Handbook Second Edition, CRC Press, Taylor & Francis Group, pp. 345-510) and software (Hansen Solubility Parameter in Practice (HSPiP v5.4.01)). Furthermore, based on the temperature dependence etc. described on page 18 of publicly available literature 1, the dispersion term dD, polarization term dP, and hydrogen bonding term dH of the active photocured product and gelling agent can be easily calculated, respectively.

[0048] The preferred SP value distance varies depending on the type of gelling agent. For example, when the gelling agent is stearyl stearate, it is preferable that the SP value distance R is between 4 and 5.5. When the gelling agent is cetyl palmitate, it is preferable that the SP value distance R is between 3.5 and 5.

[0049] The total amount of gelling agent in the ink is preferably 1% by mass or more and 10% by mass or less, and more preferably 2% by mass or more and 8% by mass or less. When the total amount of gelling agent is within this range, the ink is more likely to undergo a sol-gel phase transition and the stress generated in the image during curing is more easily relieved. On the other hand, the gelling agent is less likely to precipitate on the image surface. In the printing method of this embodiment, since the gelling agent is less likely to precipitate on the image surface, it is also possible to include a relatively large amount of gelling agent in the ink to make the ink more likely to gel.

[0050] (Colorants) The type of colorant is not particularly limited and can be appropriately selected depending on the ink's application and the type of recording medium. The ink may contain only one type of colorant or two or more. Examples of colorants include dyes and pigments. Pigments are more preferred because they have good dispersibility with the ink's components and excellent weather resistance.

[0051] Examples of dyes include oil-soluble dyes. Oil-soluble dyes can be selected from commercially available products.

[0052] On the other hand, the pigments are not particularly limited; for example, organic or inorganic pigments with the following numbers listed in the color index can be selected.

[0053] Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53:1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144, 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257; Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88; and Pigment Orange. This includes numbers such as 13, 16, 20, and 36.

[0054] Examples of blue or cyan pigments include Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17-1, 22, 27, 28, 29, 36, 60, etc.

[0055] Examples of green pigments include Pigment Green 7, 26, 36, and 50. Examples of yellow pigments include Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, etc.

[0056] Examples of black pigments include Pigment Black 7, 28, and 26. Titanium dioxide (especially rutile-type titanium dioxide) can also be used as a white pigment.

[0057] The volume-average particle size of the pigment, as measured by dynamic scattering or laser diffraction, is preferably 0.08 to 0.5 μm. The maximum particle size of the pigment is preferably 0.3 to 10 μm, and more preferably 0.3 to 3 μm. When the pigment particle size is within this range, the ink is easier to apply. In addition, the storage stability of the ink tends to be good.

[0058] The amount of colorant in the ink is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.4% by mass or more and 10% by mass or less. When the amount of colorant is within this range, it becomes easier to obtain an image of the desired color. On the other hand, the viscosity of the ink does not become excessively high, making it easier to apply the ink from the application means.

[0059] Furthermore, if the above-mentioned colorant is a pigment, the ink may contain a pigment dispersant along with the pigment. Examples of pigment dispersants include hydroxyl group-containing carboxylic acid esters, salts of long-chain polyaminoamides and high molecular weight acid esters, salts of high molecular weight polycarboxylic acids, salts of long-chain polyaminoamides and polar acid esters, high molecular weight unsaturated acid esters, polymer copolymers, modified polyurethanes, modified polyacrylates, polyether ester-type anionic surfactants, naphthalene sulfonic acid formalin condensate salts, aromatic sulfonic acid formalin condensate salts, polyoxyethylene alkyl phosphate esters, polyoxyethylene nonylphenyl ether, and stearylamine acetate. Examples of commercially available pigment dispersants include Avecia's Solsperse series and Ajinomoto Fine Techno's PB series.

[0060] The ink may further contain dispersing agents as needed. The dispersing agents are defined and selected according to the pigment. The total amount of pigment dispersant and dispersing aid is preferably 1 to 50% by mass relative to the pigment.

[0061] (Photoinitiator) Ink typically contains a photoinitiator (photopolymerization initiator). The ink may contain only one type of photoinitiator, or two or more types. When the active light-curable compound is a radical polymerizable compound, it is preferable to include a radical polymerization initiator as the photoinitiator, and when the active light-curable compound is a cationic polymerizable compound, it is preferable to include a photoacid generator as the photoinitiator.

[0062] Radical polymerization initiators include intramolecular bond cleavage type and intramolecular hydrogen abstraction type, and either type may be used.

[0063] Examples of intramolecular bond cleavage type photoinitiators include acetophenone derivatives such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenylketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; benzoin derivatives such as benzoin, benzoin methyl ether, and benzoin isopropyl ether; acylphosphine oxide derivatives such as 2,4,6-trimethylbenzoin diphenylphosphine oxide; and benzyl and methylphenylglyoxyesters.

[0064] Examples of intramolecular hydrogen abstraction type photoinitiators include benzophenone derivatives such as benzophenone, o-benzoylmethyl-4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylic benzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone derivatives such as 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone; aminobenzophenone derivatives such as Michler's ketone and 4,4'-diethylaminobenzophenone; and 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, and camphorquinone.

[0065] On the other hand, examples of photoacid generators include compounds used in chemically amplified photoresists and photocationic polymerization (see Organic Electronic Materials Research Group, ed., "Organic Materials for Imaging," Bunshin Publishing (1993), pp. 187-192).

[0066] The amount of photoinitiator in the ink depends on factors such as the type of active light and photopolymerizable compound, but is preferably 0.01% to 10% by mass, and more preferably 0.1% to 8% by mass. When the amount of photoinitiator is within this range, the ink has good curability, and printed materials can be manufactured efficiently.

[0067] (Other compounds) The ink may further contain photopolymerization initiators, polymerization inhibitors, etc., as needed. Examples of photopolymerization initiators include tertiary amine compounds, with aromatic tertiary amine compounds being preferred.

[0068] Examples of aromatic tertiary amine compounds include N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine, N,N-dimethylamino-p-benzoate ethyl ester, N,N-dimethylamino-p-benzoate isoamyl ethyl ester, N,N-dihydroxyethylaniline, triethylamine, and N,N-dimethylhexylamine. Among these, N,N-dimethylamino-p-benzoate ethyl ester and N,N-dimethylamino-p-benzoate isoamyl ethyl ester are preferred. The ink may contain only one of these compounds or two or more.

[0069] Examples of polymerization inhibitors include (alkyl)phenol, hydroquinone, catechol, resorcinol, p-methoxyphenol, t-butylcatechol, t-butylhydroquinone, pyrogallol, 1,1-picrylhydrazyl, phenothiazine, p-benzoquinone, nitrosobenzene, 2,5-di-t-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cuperone, aluminum N-nitrosophenylhydroxylamine, tri-p-nitrophenylmethyl, N-(3-oxyanilino-1,3-dimethylbutylidene)aniline oxide, dibutylcresol, cyclohexanone oxime cresol, guaiacol, o-isopropylphenol, butyraldoxime, methyl ethyl ketoxime, and cyclohexanone oxime.

[0070] Furthermore, the ink may further contain various additives and other resins. Examples of additives include surfactants, sensitizers, leveling additives, matting agents, ultraviolet absorbers, infrared absorbers, antibacterial agents, and basic compounds to improve the storage stability of the ink. Examples of basic compounds include basic alkali metal compounds, basic alkaline earth metal compounds, and basic organic compounds such as amines. Examples of other resins include resins to adjust the physical properties of the cured film, such as polyester resins, polyurethane resins, vinyl resins, acrylic resins, rubber resins, and waxes.

[0071] (Ink preparation method) The method for preparing the ink described above is not particularly limited, and it is prepared by mixing an active light-curable compound, a colorant, a gelling agent, and a photoinitiator with other components as needed. Heating may be done as needed. Alternatively, all of these may be mixed at once, or a pigment dispersant may be prepared by dispersing a colorant (especially a pigment) in some of the active light-curable compounds, and the pigment dispersant may be mixed with the other components. The resulting ink is preferably filtered through a predetermined filter.

[0072] When using pigments as colorants, dispersion is preferably carried out using a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, and paint shaker. The dispersion of pigments is adjusted by selecting the pigment, dispersant, and dispersion medium, as well as the dispersion conditions and filtration conditions.

[0073] (2) Method for manufacturing printed materials and image forming apparatus As described above, the method for manufacturing a printed material according to this embodiment may include a step of applying the above-mentioned ink to the first surface of a recording medium and curing it to form a first image (first image forming step), and a step of transporting the recording medium on which the first image has been formed (transporting step). If necessary, the method may further include a step of applying the above-mentioned ink to the second surface of the recording medium and curing it to form a second image (second image forming step), or a step of forming an overcoat layer on the first image and / or the second image (overcoat layer forming step).

[0074] The order of these processes is selected as appropriate depending on the configuration of the image forming apparatus. In the case of single-sided printing, (i) the first image forming process / transport process may be performed in this order, or (ii) the first image forming process / transport process / overcoat layer may be performed in this order.

[0075] On the other hand, there are various possible orders for double-sided printing. For example, the following order is possible, but is not limited to these. (a) First image forming process / transport process / Second image forming process / transport process (b) First image formation process / transport process / second image formation process / transport process / overcoat layer formation process (c) First image formation process / transport process / overcoat layer formation process / transport process / second image formation process / transport process / overcoat layer formation process The following describes each step.

[0076] (First image formation process and second image formation process) The first image forming step is the step of forming a first image on the first surface of the recording medium, and the second image forming step is the step of forming a second image on the second surface of the recording medium. These are substantially the same steps except for the difference in which surface of the recording medium the image is formed on.

[0077] In the first image forming step and the second image forming step, the above-mentioned ink is applied to a desired area of ​​the recording medium by a coating means and cured by a curing means.

[0078] The types of recording media that can be used in the method for manufacturing printed materials of this embodiment are not particularly limited, and examples include non-absorbent recording media made of plastics such as polyester, polyvinyl chloride, polyethylene, polyurethane, polypropylene, acrylic resin, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate and polybutadiene terephthalate, non-absorbent inorganic recording media such as metals and glass, and papers (e.g., coated paper for printing and coated paper B for printing).

[0079] Furthermore, the method of applying the ink described above is not particularly limited. One example is the application of ink by inkjet. When applying the ink by inkjet, it is preferable to set the temperature of the ink inside the inkjet recording head to the gelation temperature of the ink + 10°C or higher. This makes it difficult for the ink to gel inside the inkjet recording head or on the surface of the inkjet nozzle, and allows for stable ejection of ink droplets. On the other hand, it is preferable that the temperature of the ink inside the inkjet recording head be the gelation temperature + 30°C or lower. This suppresses the deterioration of each component in the ink.

[0080] Furthermore, the amount of ink ejected per drop from each inkjet nozzle of the inkjet recording head is preferably 0.5 to 10 pl, depending on the image resolution, and more preferably 0.5 to 2.5 pl for forming high-definition images. By applying ink with such droplet amounts, high-definition images can be stably formed.

[0081] On the other hand, the method for curing the ink is appropriately selected depending on the type and composition of the ink, but irradiation with active light is preferred. The type and wavelength of the active light to be irradiated are appropriately selected depending on the type of photoinitiator, etc., but for example, ultraviolet light with a wavelength of 365 nm to 405 nm is preferred.

[0082] Furthermore, the amount of active light irradiated onto each image is appropriately selected according to the ink composition, etc., but is set at 100 mJ / cm². 2 More than 2000mJ / cm 2 The following is preferable: 200 mJ / cm² 2 More than 1000mJ / cm 2 The following is more preferable: With this irradiation dose of active light, the ink can be cured quickly, and printed materials can be manufactured efficiently. Furthermore, by using this irradiation dose, the amount of uncured components can be reduced, and even if the formed image comes into contact with the transport means of the image forming apparatus, various components are less likely to adhere to the transport means.

[0083] In addition, the cumulative amount of active light irradiated onto the first surface of the recording medium in the first image forming step, and the cumulative amount of active light irradiated onto the second surface of the recording medium in the second image forming step, i.e., (cumulative amount of active light irradiated onto the second surface / cumulative amount of active light irradiated onto the second surface) × 100, are preferably 80% to 120%, more preferably 90% to 110%, and particularly preferably the same. Within this range, there is no need to significantly change the settings of the active light irradiation means when performing the first and second image forming steps, and printed materials can be manufactured efficiently.

[0084] (Overcoat layer formation process) The overcoat layer formation step may be any step of applying overcoat ink onto the first or second image described above and curing it. The overcoat layer may be formed on only one of the surfaces, or on both surfaces. As described above, the timing of the overcoat layer formation step is appropriately selected according to the configuration of the image forming apparatus, etc.

[0085] Here, the overcoat ink applied in the overcoat layer formation process is appropriately selected according to its application. The overcoat ink may be a clear ink or a colored ink. Examples of overcoat inks include inks containing active light-curable compounds and photoinitiators similar to the active composition-curable inks described above. However, in this case, the amount of gelling agent in the overcoat ink is preferably 5% by mass or less, and more preferably 1% by mass or less. When the amount of gelling agent is within this range, leveling becomes easier when applying the overcoat ink, and an overcoat layer with good gloss due to scattering is obtained. On the other hand, the overcoat ink may be a commercially available varnish.

[0086] The method for applying the overcoat ink is selected appropriately depending on the type of overcoat ink, the area to be coated, etc. For example, inkjet printing may be used, but bar coating, spray coating, curtain coating, roll coating, screen printing, offset printing, gravure printing, etc. may also be used.

[0087] Furthermore, the curing method for the overcoat ink is appropriately selected depending on the type of overcoat ink. If the overcoat ink contains an active light-curable compound, irradiation with active light is preferred. On the other hand, if the overcoat ink is a solvent-based ink containing a solvent or a water-based ink containing water, it can be cured by natural drying or heating.

[0088] (Conveying process) The transport process is a process that takes place after the first recording medium forming process, and involves the transport of the recording medium and the transport means of the image forming apparatus in contact. As described above, the transport process may be performed multiple times after the first image forming process.

[0089] The method of transporting the recording medium is not particularly limited, as long as it is a method that can transport the recording medium while supporting it. As shown in Figures 1 and 2, it may be various rollers (support roller 112, transport rollers 121 and 122, and reversing roller 130, etc.), or it may be a belt conveyor, etc.

[0090] (3) Image forming apparatus The configuration of the image forming apparatus is not particularly limited. For example, as shown in Figure 1, it may include a recording medium supply means 10 for supplying a recording medium, a coating means 20 for applying the ink mentioned above, a curing means 30 for curing the ink, a first transport means 110 (feed roller 111, support roller 112), a second transport means (transport rollers 121, 122), and a third transport means (reversing roller) 130 for transporting the recording medium. Furthermore, it may also include a coating means (not shown) and a curing means (not shown) for forming an overcoat layer.

[0091] The coating means 20 for applying the above-mentioned ink can have a configuration similar to that of a known inkjet device. For example, it can have a configuration comprising an ink tank for storing ink, a head carriage for housing a plurality of inkjet recording heads for applying each color ink, and an ink channel connecting the ink tank and the head carriage.

[0092] Furthermore, the curing means 30 is not particularly limited as long as it is configured to irradiate the recording medium with active light at a desired position. For example, it can be a means in which one or more light sources are arranged so that active light can be irradiated across the entire width of the recording medium. The type of light source is selected according to the desired type of active light, but a light source that does not easily generate heat, such as an LED light source, is preferred so as not to heat the ink coating.

[0093] Furthermore, each conveying means 110, 120, and 130 is not particularly limited and can be the same as, for example, various rollers and conveyors found in known image forming apparatuses. [Examples]

[0094] The following describes specific embodiments of the present invention along with comparative examples, but the present invention is not limited to these. In the embodiments, "parts" and "%" mean "parts by mass" and "mass%" respectively, unless otherwise specified.

[0095] 1. Preparation of light-curable ink (1) Preparation of materials The following components were used in the examples and comparative examples.

[0096] (Active light curable compound) As the photocurable compounds, compositions combining multiple photocurable monomers (monomer compositions) were used, as shown in Table 1 below. Table 1 also shows the SP values ​​for each monomer composition. The amounts of each component in Table 1 are in parts by mass.

[0097] [Table 1]

[0098] (Gelling agent) The compounds shown in Table 2 below were used as gelling agents. Table 2 also shows the number of carbon atoms in the linear structure of each compound, as well as the SP value of each compound. [Table 2]

[0099] (Colorants) Cyan pigment, Pigment Blue 15:4 (manufactured by Dainichi Seika Co., Ltd., Chromofine Blue 6332JC)

[0100] (others) Photoinitiator (phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BASF's "IRGACURE 819")) Polymerization inhibitor (Irgastab UV10 (manufactured by Ciba Specialty Chemicals))

[0101] (2) Preparation of light-curable ink Each compound was mixed in the composition ratios shown in Table 3 below, and the mixture was heated and stirred at 80°C to prepare 39 types of active light-curable inks that underwent a sol-gel phase transition. The obtained active light-curable inks were filtered under heat using a 3 μm Teflon® membrane filter manufactured by ADVANTEC. Table 3 also includes the SP value of the entire active light-curable compound, calculated using formula (1) below, and the SP value distance R between the SP value of the gelling agent and the SP value of the active light-curable compound. R = {4 * (dDm - dDg)} 2 +(dPm-dPg) 2 +(dHm-dHg) 2} 0.5 ...Equation (1) The dispersion term dDm for the entire photocured product, the dispersion term dDg for the gelling agent, the polarization term dPm for the entire photocured product, the polarization term dPg for the gelling agent, the hydrogen bonding term dHm for the entire photocured product, and the hydrogen bonding term dHg for the gelling agent were calculated from publicly available literature 1 (HANSEN SOLUBILITY PARAMETERS A User's Handbook Second Edition, CRC Press Taylor & Francis Group, pp. 345-510) and software (Hansen Solubility Parameter in Practice (HSPiP v5.4.01)).

[0102] (3) Preparation of overcoat ink For the overcoat ink, we prepared FD Clear Coat TDP manufactured by Toyo Ink Co., Ltd.

[0103] 2. Manufacturing of printed materials (Example 1) The active light-curable ink with the composition shown in Table 3 was loaded into the ink tank of the coating means 20 of the inkjet recording device shown in Figure 2. Then, ink was applied to the first surface of the recording medium 1 (A4 size coated paper (OK Topcoat; manufactured by Oji Paper Co., Ltd.)) from the piezo-type inkjet nozzle of the coating means 20 to form a first coating film. Subsequently, light with a wavelength of 395 nm was applied from the curing means 30 to the first coating film (first surface) with an integrated light amount of 400 mJ / cm². 2 The recording medium 1 was then irradiated in such a manner. The recording medium 1 was then inverted using the inversion roller 130. The ink was then applied to the second surface of the recording medium 1 from the coating means 20, and light with a wavelength of 395 nm was applied from the curing means 30, with an integrated light amount of 400 mJ / cm² applied to the second coating film (second surface). 2 The light was applied in such a manner. Then, the recording medium 1, after the second coating film had formed, was gripped by the transport rollers 121 and 122 and discharged. The first and second coating films each formed solid images. At this time, the transport rollers 121 and 122 came into contact with the second image and the first image, respectively. The printing speed (movement speed of the recording medium) was set to 600 mm / s.

[0104] Subsequently, the above-mentioned overcoat ink was applied to the first and second surfaces of the recording medium, which had images formed on the first and second surfaces respectively, and then cured (solidified).

[0105] (Examples 2-33 and Comparative Examples 1-6) The printed material was manufactured in the same manner as in Example 1, except that the composition of the active light-curable ink and the printing conditions (combined light intensity difference between the first and second surfaces) were changed as shown in Table 3.

[0106] 3. Evaluation The glossiness and adhesion of the overcoat layer of the printed materials obtained by the above manufacturing process were evaluated according to the following criteria. The results are shown in Table 3. Furthermore, curl evaluation was performed on the printed materials of Example 5 and 20-24. The results are shown in Table 4.

[0107] (Glossiness evaluation) Glossiness was evaluated using a PG-2M (manufactured by Nippon Denshoku Industries Co., Ltd.) at a 60° rating for the first and second images before the formation of the overcoat layer. The evaluation criteria are as follows: Glossiness difference: Glossiness of the first image surface / Glossiness of the second image surface ◎: Gloss difference between 0.96 and 1.04 ○: Gloss difference between 0.90 and 0.95, and between 1.05 and 1.10. △: Gloss difference between 0.85 and 0.89, and between 1.11 and 1.15. ×: Gloss difference between 0.80 and 0.84, or between 1.16 and 1.20 ××:: Gloss difference of 0.79 or less, or 1.21 or more.

[0108] (Overcoat layer adhesion evaluation) The surfaces of the first and second images, after the overcoat layer had formed, were cross-cut into a grid of 25 squares with a width of 1 mm. Then, cellophane adhesive tape (LP-24, manufactured by Nichiban Co., Ltd.) was applied to the cross-cut grid, and the tape was immediately peeled off vertically. The area peeled off due to the tape application was identified and evaluated. The evaluation criteria are as follows. ◎: Number of peeled sheets: 0 ○: 1-3 sheets to peel off △: Number of sheets to peel off: 4-6 ×: More than 7 sheets to peel off.

[0109] (Curl evaluation (curl evaluation)) A 210mm (length) x 105mm (width) sheet of Oji Paper's OK Topcoat (128g) was printed with 100% ink density, and the distance from edge to edge in the width direction was measured when viewed from above. If the sheet curls, the above distance will be shorter when viewed from above. The evaluation criteria are as follows. ○: Distance from end to end is 104 mm or more △: Distance from end to end is 103mm or more but less than 104mm ×: Distance from end to end is less than 103 mm

[0110] [Table 3]

[0111] [Table 4]

[0112] As shown in Table 3 above, when using an ink that combines an active light-curable compound with a gelling agent containing relatively short linear structures (10 to 16 in the case of ketone compounds, and 12 to 18 in the case of ester compounds), differences in gloss were less likely to occur even when the first and second images came into contact with the transport means (Examples 1-33). It is thought that by using the above gelling agent, even if the gelling agent came into contact with each image of the cured ink and the transport means, the gelling agent was less likely to precipitate on the surface and less likely to adhere to the transport means. Furthermore, it is thought that the adhesion of the overcoat layer was improved because the gelling agent was less likely to precipitate on the surface (Examples 1-33). In addition, even when the amount of gelling agent in the ink was increased, differences in gloss and a decrease in the adhesion of the overcoat layer were less likely to occur.

[0113] In contrast, printed materials using inks containing gelling agents with relatively long linear structures tended to exhibit differences in gloss (e.g., Comparative Example 4). It is thought that some of the ink adhered to the transport mechanism. Furthermore, depending on the combination of the gelling agent and the photocurable compound, the adhesion of the overcoat layer was very low (Comparative Examples 1-3, 5, and 6). [Industrial applicability]

[0114] According to the printing method of the present invention, even if the cured product of the active light-curable ink comes into contact with the transport means of the printing apparatus, the components in the cured product are less likely to adhere to the transport means. Therefore, high-quality printed materials can be manufactured. The present invention is expected to contribute to the further popularization of image formation methods using active light-curable inks. [Explanation of Symbols]

[0115] 1. Recording medium 100 Image forming apparatus 10 Recording medium supply means 20 Coating means 30 Curing means 110 First conveying means 111 Paper feed roller 112 Support roller 120 Second conveying means 121, 122 Conveyor rollers 130 Third conveying means (reversing roller)

Claims

1. A process of applying an active light-curable ink to the first surface of a recording medium and curing it to form a first image, A step of transporting the recording medium on which the first image has been formed, A method for manufacturing printed materials, The aforementioned light-curable ink is One or more reactive light-curable compounds, A gelling agent comprising a ketone compound represented by general formula (1) and / or an ester compound represented by general formula (2), R １ -C(=O)-R ２ (1) (R １ and R ２ (Each of these independently represents a hydrocarbon group containing a linear structure with 10 to 16 carbon atoms.) R ３ -COO-R ４ (2) (R ３ and R ４ (Each of these independently represents a hydrocarbon group containing a linear structure with 12 to 18 carbon atoms.) Colorants and, Includes, The SP value of the entire photocurable compound is 16.8 or higher and 18.5 or lower. The SP value distance R between the SP value of the entire active photocurable compound and the SP value of the gelling agent, as represented by the following formula (1), is 2 or more and 5.5 or less. In the process of transporting the recording medium, the first image comes into contact with the transport means of the image forming apparatus. A method for manufacturing printed materials. R={4*(dDm-dDg) 2 + (dPm-dPg) 2 + (dHm-dHg) 2} 0.5...Formula (1) (In the above formula (1), dDm represents the dispersion term of the total evaporation energy of the active photocurable compound, dPm represents the polarization term of the total evaporation energy of the active photocurable compound, dHm represents the hydrogen bonding term of the total evaporation energy of the active photocurable compound, dDg represents the dispersion term of the evaporation energy of the gelling agent, dPg represents the polarization term of the evaporation energy of the gelling agent, dHg represents the hydrogen bonding term of the evaporation energy of the gelling agent.

2. The process further includes applying the light-curable ink to the second surface of the recording medium and curing it to obtain a second image. A method for manufacturing a printed article according to claim 1.

3. In the steps for obtaining the first image and the second image, the coating film of the active light-curable ink is irradiated with active light. The integrated amount of active light irradiated onto the second surface is set to be 80% or more and 120% or less of the integrated amount of active light irradiated onto the first surface. The method for manufacturing a printed article according to claim 2.

4. The gelling agent includes an ester compound represented by the general formula (2), R in the general formula (2) ３ and R ４ each independently represent a hydrocarbon group comprising a linear structure having 15 to 18 carbon atoms, A method for manufacturing a printed article according to claim 1.

5. The amount of the gelling agent in the light-curable ink is 2% by mass or more and 10% by mass or less. A method for manufacturing a printed article according to claim 1.

6. The gelling agent is stearyl stearate, The SP value distance R is 4 or more and 5.5 or less. A method for manufacturing a printed article according to claim 1.

7. The gelling agent is cetyl palmitate. The SP value distance R is 3.5 or more and 5 or less. A method for manufacturing a printed article according to claim 1.

8. The process further includes the step of forming an overcoat layer on the first image and / or the second image. The method for manufacturing a printed article according to claim 2.

9. The step of forming the overcoat layer is, This is the process of applying and curing an activated light-curing overcoat ink. The method for manufacturing a printed article according to claim 8.

10. The amount of gelling agent in the aforementioned light-curable overcoat ink is 5% by mass or less. The method for manufacturing a printed article according to claim 9.

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