Image formation methods

Abstract

To provide an image forming method using an active energy ray curable liquid having applicability and adhesion to a toner image.SOLUTION: An image forming method of the present invention has the steps of: applying an active energy ray curable liquid to a surface of a toner image fixed to a surface of a recording medium; and irradiating the active energy ray curable liquid applied to the surface of the toner image with an active energy ray to cure the active energy ray curable liquid. The toner image includes a binder resin, a colorant, and a mold release agent. The active energy ray curable liquid includes at least an active energy ray polymerizable compound and a (meth)acrylic resin. The binder resin includes a styrene acrylic resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming method. [Background technology]

[0002] In recent years, the production printing (PP) market has adopted electrophotographic image formation methods, which do not require a plate-making process and can produce the required number of prints on demand. However, the PP market is demanding improvements in the image quality and durability of images obtained by electrophotographic image formation methods.

[0003] Therefore, a method has been considered in which an actinic ray curable liquid (varnish) is applied to the surface of an image obtained by an electrophotographic image forming method to form a coating film (varnish layer) of the actinic ray curable liquid.

[0004] For example, Patent Document 1 describes a method for producing a printed matter in which a photocurable varnish containing a surfactant to improve coatability is applied to the surface of an image formed using a toner containing a petroleum wax to form a varnish layer. According to Patent Document 1, the use of the toner makes it possible to provide a printed matter with excellent adhesion to the varnish. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-078485 Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors conducted research and found that when they formed an image using the toner and varnish described in Patent Document 1, they were able to wet and spread the varnish over the surface of the image to form a varnish layer, but when the varnish layer was cured by exposure to actinic rays, the varnish layer sometimes peeled off from the surface of the image.

[0007] The present invention has been made in view of the above points, and has as its object to provide an image forming method using an actinic ray curable liquid that has good coatability and adhesion to a toner image. [Means for solving the problem]

[0008] The image forming method of the present invention comprises the steps of applying an actinic ray-curable liquid to the surface of a toner image fixed on the surface of a recording medium, and irradiating the actinic ray-curable liquid applied to the surface of the toner image with actinic rays to cure the actinic ray-curable liquid, wherein the toner image contains a binder resin, a colorant, and a release agent, the actinic ray-curable liquid contains at least an actinic ray-polymerizable compound and a (meth)acrylic resin, and the binder resin contains a styrene-acrylic resin. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an image forming method using an actinic ray curable liquid that has good coatability and adhesion to a toner image. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an exemplary configuration of an image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0012] 1. Image forming method An image forming method according to one embodiment of the present invention includes: (1) a step of applying an actinic ray-curable liquid to the surface of a toner image fixed on the surface of a recording medium; and (2) a step of irradiating the actinic ray-curable liquid applied to the surface of the toner image with actinic rays to cure the actinic ray-curable liquid.

[0013] 1-1. Step of applying actinic ray curable liquid The step of applying an actinic ray curable liquid according to one embodiment of the present invention is a step of applying an actinic ray curable liquid to the surface of a toner image fixed on the surface of a recording medium.

[0014] [Toner image] The toner image according to one embodiment of the present invention is formed using a toner containing toner particles including a binder resin, a colorant, and a release agent.

[0015] (binder resin) The adhesive resin may be any thermoplastic resin, and may be either an amorphous resin or a crystalline resin.

[0016] Amorphous resins are resins that exhibit amorphous properties, having a glass transition temperature (Tg) but no clear endothermic peak during heating, as determined by differential scanning calorimetry (DSC). The monomers that make up the amorphous resins are different from those that make up crystalline resins (described below), and can be distinguished by analysis such as NMR.

[0017] A crystalline resin is a resin that exhibits a clear endothermic peak rather than a stepwise endothermic change in differential scanning calorimetry (DSC). A clear endothermic peak is one whose half-width is 15°C or less when measured at a heating rate of 10°C / min in DSC.

[0018] Among these, the binder resin preferably contains a styrene-acrylic resin as an amorphous resin, which improves compatibility with the crystalline resin (described below) and improves low-temperature fixability.

[0019] (styrene-acrylic resin) Styrene-acrylic resins have a molecular structure of radical polymers of compounds with radically polymerizable unsaturated bonds and can be synthesized, for example, by radical polymerization of the compounds. Examples of such compounds include styrene monomer and its derivatives, and (meth)acrylic acid monomer and its derivatives. These compounds may be used alone or in combination. "(Meth)acrylic acid" is a general term for acrylic acid and methacrylic acid, meaning either or both.

[0020] Examples of the styrene monomer and its derivatives include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, 2,4-dimethylstyrene and 3,4-dichlorostyrene.

[0021] Examples of the (meth)acrylic acid and its derivatives include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.

[0022] Among the above (meth)acrylic acid and its derivatives, acrylic acid, methyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate, and 2-ethylhexyl methacrylate are preferred.

[0023] From the viewpoint of controlling the plasticity of the styrene-acrylic resin, the content of structural units derived from styrene monomer in the styrene-acrylic resin is preferably 40 to 90% by mass, and the content of structural units derived from (meth)acrylic acid in the styrene-acrylic resin is preferably 10 to 60% by mass.

[0024] The styrene-acrylic resin may further contain structural units derived from other monomers besides the styrene monomer and (meth)acrylic ester monomer. The other monomer is preferably a compound that forms an ester bond with a hydroxy group (-OH) derived from a polyhydric alcohol or a carboxy group (-COOH) derived from a polycarboxylic acid. In other words, the styrene-acrylic resin is preferably a polymer obtained by further polymerizing a compound (amphoteric compound) that is addition polymerizable with the styrene monomer and (meth)acrylic ester monomer and has a carboxy group or a hydroxy group.

[0025] Examples of the amphoteric compound include compounds having a carboxy group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl esters, and itaconic acid monoalkyl esters, and compounds having a hydroxy group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

[0026] The content of the structural unit derived from the amphoteric compound in the styrene-acrylic resin is preferably 0.5 to 20% by mass.

[0027] The styrene-acrylic resin can be obtained by adding any commonly used polymerization initiator, such as peroxides, persulfides, or azo compounds, to the polymerization of the styrene monomer, and polymerizing the mixture by a known polymerization method, such as bulk polymerization, solution polymerization, emulsion polymerization, miniemulsion polymerization, suspension polymerization, or dispersion polymerization. During polymerization, commonly used chain transfer agents, such as alkyl mercaptans or mercapto fatty acid esters, can be used to adjust the molecular weight.

[0028] The content of the styrene-acrylic resin is more preferably 50% by mass or more and 90% by mass or less, and particularly preferably 60% by mass or more and 80% by mass or less, based on the total mass of the resin components constituting the binder resin. By making the styrene-acrylic resin content 50% by mass or more based on the total mass of the resin components constituting the binder resin, compatibility with the crystalline resin is improved, resulting in improved low-temperature fixability. Furthermore, by making the styrene-acrylic resin content 90% by mass or less based on the total mass of the resin components constituting the binder resin, it is possible to add 10% by mass or more of other low-melting-point resins, such as ethylene-vinyl copolymers, thereby improving meltability at low temperatures and improving fixability.

[0029] The styrene-acrylic resin preferably has a glass transition temperature (Tg) of 25° C. or higher and 60° C. or lower, and more preferably 35° C. or higher and 55° C. or lower. The glass transition temperature (Tg) of the styrene-acrylic resin can be measured using, for example, a thermal analyzer "Diamond DSC" (manufactured by PerkinElmer).

[0030] The weight-average molecular weight (Mw) of the styrene-acrylic resin is preferably 10,000 to 100,000, and the number-average molecular weight (Mn) is preferably 20,000 to 50,000. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the styrene-acrylic resin can be measured, for example, using a GPC apparatus "HLC-8120GPC" and a column "TSKguard column + TSKgel Super HZM-M triple column" (both manufactured by Tosoh Corporation).

[0031] (aromatic polyester resin) The toner particles according to an embodiment of the present invention more preferably contain an aromatic polyester resin as the amorphous resin. In the present invention, the term "aromatic polyester resin" refers to a polyester resin that is a polycondensate of an aromatic monomer obtained by a polycondensation reaction between a divalent or higher aromatic carboxylic acid and a divalent or higher aromatic alcohol.

[0032] Furthermore, the aromatic polyester resin according to an embodiment of the present invention preferably has a high acid value. The acid value of the aromatic polyester resin is preferably from 10 to 50, and more preferably from 20 to 50. When the acid value is 10 or more, the affinity between the terminal carboxyl groups of the aromatic polyester resin and the coating film formed by curing the actinic radiation-curable liquid is improved, thereby improving adhesion.

[0033] Furthermore, from the viewpoint of increasing the strength (toughness) of the toner image, the aromatic polyester resin preferably contains a monomer unit having a benzene ring, and more preferably contains the monomer unit having a benzene ring in a side chain of the resin.

[0034] The divalent or higher aromatic carboxylic acid is a compound having two or more carboxy groups in one molecule.

[0035] The type of divalent or higher aromatic carboxylic acid used in preparing the aromatic polyester resin is not particularly limited, and known divalent or higher carboxylic acids and their derivatives can be used. Furthermore, as long as an amorphous resin can be formed, a divalent or higher saturated aliphatic carboxylic acid may also be used in combination. Furthermore, the polycarboxylic acid may be used alone or in combination of two or more types.

[0036] Examples of the divalent or higher carboxylic acids include aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, t-butylisophthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-phenylenediacetic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and anthracenedicarboxylic acid; aromatic tricarboxylic acids such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid (trimesic acid), 1,2,4-naphthalenetricarboxylic acid, and hemimellitic acid; aromatic tetracarboxylic acids such as pyromellitic acid and 1,2,3,4-butanetetracarboxylic acid; and aromatic hexacarboxylic acids such as mellitic acid. Lower alkyl esters and acid anhydrides of these compounds can also be used.

[0037] The type of the dihydric or higher aromatic alcohol is not particularly limited, but from the viewpoint of chargeability and toner strength, it is preferable to use a known dihydric or higher alcohol and its derivative. Note that saturated aliphatic polyhydric alcohols may also be used in combination as long as an amorphous resin can be obtained.

[0038] The above-mentioned divalent or higher aromatic alcohol is a compound having two or more hydroxy groups in one molecule.

[0039] Examples of the dihydric or higher aromatic alcohols include bisphenols such as bisphenol A and bisphenol F, alkylene oxide adducts of bisphenols such as ethylene oxide adducts and propylene oxide adducts of these, 1,3,5-benzenetriol, 1,2,4-benzenetriol, 1,3,5-trihydroxymethylbenzene, etc. Derivatives of these may also be used.

[0040] Among the above-mentioned dihydric or higher aromatic alcohols, it is preferable to use bisphenol A compounds such as ethylene oxide adducts and propylene oxide adducts of bisphenol A. By using the above-mentioned bisphenol A compounds, it is easy to optimize the thermal properties.

[0041] Furthermore, trihydric or higher polyhydric alcohols may be used. The number of carbon atoms in the trihydric or higher polyhydric alcohols is not particularly limited, but from the viewpoint of optimizing thermal properties, polyhydric alcohols having 3 to 20 carbon atoms are preferred. The trihydric or higher polyhydric alcohols may be used alone or in combination of two or more.

[0042] The method for producing the aromatic polyester resin is not particularly limited, and it can be produced using a general polyester polymerization method in which a divalent or higher carboxylic acid and a divalent or higher alcohol are reacted in the presence of a known catalyst.

[0043] Examples of the catalyst include titanium catalysts such as titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, and titanium tetrabutoxide, and tin catalysts such as dibutyltin dichloride, dibutyltin oxide, and diphenyltin oxide.

[0044] The weight-average molecular weight (Mw) of the aromatic polyester resin is not particularly limited, but is preferably 5,000 to 100,000, more preferably 5,000 to 50,000. The number-average molecular weight (Mn) of the aromatic polyester resin is preferably 2,000 to 10,000, more preferably 2,000 to 5,000. When the weight-average molecular weight (Mw) of the aromatic polyester resin is 5,000 or more, the heat-resistant storage stability of the toner can be improved, and when the weight-average molecular weight (Mw) is 100,000 or less, the low-temperature fixability can be further improved. When the number-average molecular weight (Mn) of the aromatic polyester resin is 2,000 or more, heat resistance can be maintained, and when it is 10,000 or less, meltability can be ensured. The weight-average molecular weight (Mw) and the number-average molecular weight (Mn) can be measured using the GPC apparatus described above. The polyester resin is a resin containing 50 mol% or more polyester units.

[0045] The content of the aromatic polyester resin is preferably 1% by mass or more and 20% by mass or less, based on the total mass of the resin components constituting the binder resin. By making the content of the aromatic polyester resin 1% by mass or more, based on the total mass of the resin components constituting the binder resin, the adhesion of the actinic ray-curable liquid is improved. Furthermore, by making the content 20% by mass or less, the melting property is ensured.

[0046] (aliphatic polyester resin) The toner particles according to an embodiment of the present invention preferably contain an aliphatic polyester resin as the crystalline resin, which can ensure low-temperature fixability.

[0047] The aliphatic polyester resin is preferably a polyester resin obtained by a polycondensation reaction between a divalent or higher aliphatic carboxylic acid and a divalent or higher aliphatic alcohol.

[0048] The divalent or higher aliphatic carboxylic acid compound is a compound having two or more carboxy groups in one molecule, and alkyl esters, acid anhydrides and acid chlorides of the aliphatic carboxylic acid compound can be used.

[0049] The above-mentioned dihydric or higher aliphatic alcohol compound is a compound having two or more hydroxy groups in one molecule.

[0050] Examples of the divalent or higher aliphatic carboxylic acid compounds include divalent aliphatic carboxylic acids such as oxalic acid, succinic acid, malonic acid, adipic acid, β-methyladipic acid, pimelic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, hexahydroterephthalic acid, tartaric acid, and mucic acid, and trivalent aliphatic carboxylic acids such as citric acid. Among the aliphatic carboxylic acid compounds, divalent aliphatic carboxylic acids are preferred. The use of the divalent or higher aliphatic carboxylic acids can enhance the crystallinity of the crystalline polyester resin. The aliphatic carboxylic acids may be used alone or in combination.

[0051] Examples of the dihydric or higher aliphatic alcohol compounds include dihydric linear aliphatic alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, octanediol, decanediol, and dodecanediol; dihydric alicyclic alcohols such as cyclohexanediol; and trihydric or higher aliphatic alcohols such as glycerin and pentaerythritol. The above aliphatic alcohol compounds may be used alone or in combination of two or more.

[0052] Among the dihydric or higher aliphatic alcohol compounds, dihydric aliphatic alcohols are preferred, and dihydric linear aliphatic alcohols are more preferred. Use of dihydric aliphatic alcohols can enhance the crystallinity of the aliphatic polyester resin.

[0053] When forming an aliphatic polyester resin, the reaction can be easily controlled by using a divalent or higher aliphatic carboxylic acid and a divalent aliphatic alcohol component, and a resin with the desired molecular weight can be obtained.

[0054] Furthermore, a straight-chain aliphatic hydroxycarboxylic acid may be used in combination with the above-mentioned divalent or higher aliphatic carboxylic acids and / or divalent or higher aliphatic alcohols. Examples of the straight-chain aliphatic hydroxycarboxylic acids include 5-hydroxypentanoic acid, 6-hydroxyhexanoic acid, 7-hydroxypentanoic acid, 8-hydroxyoctanoic acid, 9-hydroxynonanoic acid, 10-hydroxydecanoic acid, 12-hydroxydodecanoic acid, 14-hydroxytetradecanoic acid, 16-hydroxyhexadecanoic acid, 18-hydroxyoctadecanoic acid, and lactone compounds cyclized from these hydroxycarboxylic acids, or alkyl esters with alcohols having 1 to 3 carbon atoms. The straight-chain aliphatic hydroxycarboxylic acids may be used alone or in combination of two or more.

[0055] The ratio of the divalent or higher aliphatic alcohol to the divalent or higher aliphatic carboxylic acid in the monomers for synthesizing the aliphatic polyester resin is preferably an equivalent ratio [OH] / [COOH] of the hydroxy group [OH] of the aliphatic alcohol to the carboxy group [COOH] of the aliphatic carboxylic acid of 2.0 / 1.0 to 1.0 / 2.0, more preferably 1.5 / 1.0 to 1.0 / 1.5, and particularly preferably 1.2 / 1.0 to 1 / 1.2.

[0056] The melting point (Tm) of the aliphatic polyester resin is preferably 65 to 85°C, and more preferably 75 to 85°C. When the melting point (Tm) of the aliphatic polyester resin is 65°C or higher, the low-temperature fixability is good. When the melting point (Tm) is 85°C or lower, the high-temperature storage stability is good. The melting point (Tm) of the aliphatic polyester resin is the temperature at the peak top of the endothermic peak, and can be measured, for example, using a thermal analyzer "Diamond DSC."

[0057] The weight average molecular weight (Mw) of the aliphatic polyester resin is preferably 5,000 or more and 50,000 or less. The number average molecular weight (Mn) of the aliphatic polyester resin is preferably 2,000 or more and 10,000 or less. By making the weight average molecular weight (Mw) of the crystalline polyester resin 5,000 or more, low-temperature fixability can be improved, and by making it 50,000 or less, low-temperature fixability can be achieved. Furthermore, by making the number average molecular weight (Mn) of the crystalline polyester resin 2,000 or more, storage stability can be ensured, and by making it 10,000 or less, low-temperature fixability can be ensured. The weight average molecular weight (Mw) and number average molecular weight (Mn) of the aliphatic polyester resin can be measured using the GPC device described above.

[0058] The content of the crystalline polyester resin is preferably 2% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, based on the total mass of the resin components constituting the binder resin. By making the content of the crystalline polyester resin 5% by mass or more based on the total mass of the toner, sufficient plasticity can be obtained and low-temperature fixability can also be improved. Furthermore, by making the content 15% by mass or less, excellent thermal stability and physical stability can be achieved.

[0059] The acid value of the aliphatic polyester resin is preferably 5 mgKOH / g to 30 mgKOH / g, more preferably 10 mgKOH / g to 25 mgKOH / g, and even more preferably 15 mgKOH / g to 25 mgKOH / g. The acid value is the mass of potassium hydroxide (KOH) required to neutralize the acid contained in 1 g of sample, expressed in mg. The acid value of the resin can be determined in accordance with JIS K0070-1992.

[0060] There are no particular limitations on the method for producing the aliphatic polyester resin, and it can be produced using a general polyester polymerization method in which a divalent or higher carboxylic acid and a divalent or higher alcohol are reacted in the presence of a known catalyst.

[0061] The reaction catalyst and reaction conditions are the same as those usable for producing the amorphous resin described above.

[0062] The binder resin may also contain a hybrid crystalline polyester resin.

[0063] Hybrid crystalline polyester resin is a crystalline polyester resin modified with styrene-acrylic resin. "Crystalline polyester resin modified with styrene-acrylic resin" means that the crystalline polyester resin segment and the styrene-acrylic resin segment are chemically bonded. The crystalline polyester resin segment refers to the resin portion of the hybrid crystalline polyester resin that originates from the crystalline polyester resin, i.e., the molecular chain with the same chemical structure as the crystalline polyester resin. The styrene-acrylic resin segment refers to the resin portion of the hybrid crystalline polyester resin that originates from the styrene-acrylic resin, i.e., the molecular chain with the same chemical structure as the styrene-acrylic resin.

[0064] The hybrid crystalline polyester resin can also be obtained by carrying out a polymerization reaction to produce a styrene-acrylic resin in the presence of a crystalline polyester resin, or by carrying out a polymerization reaction to produce a crystalline polyester resin in the presence of a pre-prepared styrene-acrylic resin.

[0065] (colorant) The toner particles according to an embodiment of the present invention contain a colorant, examples of which include a black pigment and a chromatic pigment.

[0066] Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, as well as magnetic powders such as magnetite and ferrite.

[0067] Examples of the chromatic pigments include CI Pigment Red 2, 3, 5, 7, 15, 16, 48:1, 48:3, 53:1, 57:1, 81:4, 122, 123, 139, 144, 149, 166, 177, 178, 208, 209, 222, 238, 269, CI Pigment Orange 31, 43, CI Pigment Yellow 3, Examples of pigments include CI Pigment Green 9, 14, 17, 35, 36, 65, 74, 83, 93, 94, 98, 110, 111, 138, 139, 153, 155, 180, 181, 185, CI Pigment Green 7, CI Pigment Blue 15:3, 15:4, 60, and phthalocyanine pigments whose central metal is zinc, titanium, magnesium, etc. These pigments may be used alone or in combination of two or more.

[0068] Furthermore, a chromatic dye may be used as the coloring material.

[0069] Examples of the chromatic dyes include CI Solvent Red 1, 3, 14, 17, 18, 22, 23, 49, 51, 52, 58, 63, 87, 111, 122, 127, 128, 131, 145, 146, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 176, Examples of suitable dyes include CI Solvent Yellow 179, pyrazolotriazole azo dyes, pyrazolotriazole azomethine dyes, pyrazolone azo dyes, pyrazolone azomethine dyes, CI Solvent Yellow 19, CI Solvent Yellow 44, CI Solvent Yellow 77, CI Solvent Yellow 79, CI Solvent Yellow 81, CI Solvent Yellow 82, CI Solvent Yellow 93, CI Solvent Yellow 98, CI Solvent Yellow 103, CI Solvent Yellow 104, CI Solvent Yellow 112, CI Solvent Blue 25, CI Solvent Blue 36, CI Solvent Blue 60, CI Solvent Blue 70, CI Solvent Blue 93, and CI Solvent Blue 95. These dyes may be used alone or in combination of two or more.

[0070] In the color toner, the content of the black or chromatic colorant is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 4 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the binder resin. By making the content of the colorant 1 part by mass or more, the color development of the obtained image is sufficient. Furthermore, by making the content of the colorant 20 parts by mass or less, the fixability is improved.

[0071] Furthermore, a white pigment may be used as the coloring material.

[0072] Examples of the white pigment include inorganic pigments such as heavy calcium carbonate, light calcium carbonate, titanium oxide, aluminum hydroxide, titanium white, talc, calcium sulfate, barium sulfate, zinc oxide, magnesium oxide, magnesium carbonate, amorphous silica, colloidal silica, white carbon, kaolin, calcined kaolin, delaminated kaolin, aluminosilicate, sericite, bentonite, and smexite; and organic pigments such as polystyrene resin particles and urea formalin resin particles. Hollow-structured pigments such as hollow resin particles and hollow silica are also included. Among the white pigments, titanium oxide is preferred from the viewpoints of chargeability and hiding power. Titanium oxide may have any crystal structure, such as anatase, rutile, or brookite.

[0073] (mold release agent) The toner according to an embodiment of the present invention contains a release agent. The release agent is not particularly limited, and any known release agent can be used.

[0074] Examples of the release agent include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax, long-chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, ester waxes such as behenyl behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitate, and distearyl maleate, and amide waxes such as ethylenediamine behenylamide and tristearyl trimellitate amide.

[0075] The content of the release agent is preferably 1 part by mass or more and 30 parts by mass or less, and more preferably 5 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the binder resin. By setting the content of the release agent to 1 part by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the binder resin, sufficient fixing and separating properties can be obtained.

[0076] Examples of methods for introducing a release agent into toner particles include a method in which fine particles consisting of only the release agent are aggregated and fused together with amorphous resin particles, crystalline resin particles, etc. in an aqueous medium during the aggregation and fusion process of the toner manufacturing method (described below). The release agent fine particles can be obtained as a dispersion in which the release agent is dispersed in an aqueous medium. Alternatively, a dispersion of the release agent fine particles can be prepared by heating an aqueous medium containing a surfactant to the melting point of the release agent or higher, adding the molten release agent solution, applying mechanical energy such as mechanical stirring or ultrasonic energy to finely disperse the mixture, and then cooling the mixture.

[0077] Furthermore, when the amorphous resin is a styrene-acrylic resin or the like, the release agent can be incorporated into the toner particles by compounding it with the amorphous resin particles (styrene-acrylic resin particles) that will be subjected to the aggregation and fusion processes. Specifically, the release agent is dissolved in a solution of polymerizable monomers for forming the styrene-acrylic resin, which is then added to an aqueous medium containing a surfactant. As described above, mechanical energy such as mechanical stirring or ultrasonic energy is applied to finely disperse the mixture. A polymerization initiator is then added and polymerization is carried out at the desired polymerization temperature. This is known as mini-emulsion polymerization, in which a dispersion of amorphous resin particles containing a release agent is prepared.

[0078] (charge control agent) The toner according to an embodiment of the present invention may contain a charge control agent, if necessary. The charge control agent is not particularly limited, and known charge control agents can be used.

[0079] Examples of charge control agents include known compounds such as nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salts, azo metal complexes, and metal salicylate salts. The use of charge control agents allows for the production of toners with excellent charging properties. The content of the charge control agent can be 0.1 to 5 parts by mass per 100 parts by mass of the binder resin.

[0080] (external additives) The toner according to an embodiment of the present invention may contain external additives as needed. In order to improve fluidity, chargeability, cleaning properties, etc., external additives such as a fluidizing agent, a cleaning aid, etc., which are so-called post-treatment agents, may be added.

[0081] Examples of external additives include inorganic oxide fine particles such as silica fine particles, alumina fine particles, and titanium oxide fine particles; inorganic stearic acid compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles; and inorganic titanic acid compound fine particles such as strontium titanate and zinc titanate. The external additives may be used singly or in combination of two or more. The amount of the external additives (the total amount when multiple external additives are used) added is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, per 100 parts by weight of toner.

[0082] The toner particles according to an embodiment of the present invention preferably have an average particle size of 3 μm to 9 μm, more preferably 3 μm to 8 μm, in terms of volume-based median diameter. For example, when produced by an emulsion aggregation method (described below), the average particle size of the toner particles can be controlled by the concentration of the aggregating agent used, the amount of organic solvent added, the fusion time, and the polymer composition. By setting the volume-based median diameter to 3 μm to 9 μm, transfer efficiency can be increased, resulting in improved image quality.

[0083] The volume-based median diameter of toner particles can be measured and calculated using a measuring device such as a "Multisizer 3" (manufactured by Beckman Coulter) connected to a computer system equipped with the data processing software "Software V3.51."

[0084] The toner particles according to an embodiment of the present invention preferably have an average circularity of 0.930 to 1.000, more preferably 0.950 to 0.995. By adjusting the average circularity of the toner particles to 0.930 to 1.000, transfer efficiency can be improved. The average circularity of the toner particles can be measured, for example, using a flow particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation).

[0085] The toner particles according to an embodiment of the present invention preferably have a softening point (Tsp) of 70°C or higher and 110°C or lower, and more preferably 80°C or higher and 100°C or lower. By setting the softening point to 70°C or higher, image formation can be performed without placing a burden on the colorant, thereby achieving a wider and more stable color reproducibility. Furthermore, by setting the softening point to 110°C or lower, the effect on the colorant of heat applied to the toner particles during fixing can be further reduced. The softening point of the toner particles can be determined, for example, using a flow tester CFT-500 (manufactured by Shimadzu Corporation).

[0086] [Toner manufacturing method] The method for producing the toner according to an embodiment of the present invention is not particularly limited, and the toner can be produced by a known method.

[0087] Examples of methods for producing the toner include a kneading and pulverization method, an emulsion dispersion method, a suspension polymerization method, a dispersion polymerization method, an emulsion polymerization method, an emulsion aggregation method, a mini-emulsion polymerization aggregation method, and an encapsulation method. Among these, the emulsion polymerization aggregation method is preferred from the viewpoints of uniformity of particle size, controllability of shape, and ease of forming a core-shell structure. Here, a method for producing a toner using the emulsion polymerization aggregation method will be described.

[0088] The emulsion aggregation method is a method of forming a toner by mixing a dispersion of fine resin particles (hereinafter also referred to as "resin particles") dispersed with a surfactant or dispersion stabilizer with a dispersion of toner constituent components such as fine colorant particles, adding an aggregating agent to aggregate the particles to the desired toner particle size, and then, either after or simultaneously with the aggregation, fusing the resin particles together and controlling the shape.

[0089] According to the emulsion aggregation method, a dispersion of binder resin particles obtained by emulsion polymerization is mixed with particles of a colorant, a release agent, a charge control agent, an external additive, and the like, which are optionally added, and these are aggregated, associated, or fused together until particles of a desired particle size are obtained, and then external additives are added as needed to obtain toner particles.

[0090] According to the emulsion aggregation method, a dispersion of binder resin particles is obtained by dropping a solution in which a binder resin is dissolved into a poor solvent, and the resulting dispersion is mixed with particles of a colorant, a release agent, a charge control agent, an external additive, and the like, which are optionally added, and these are aggregated, associated, or fused together until particles of a desired particle size are obtained, and then external additives are added as needed, thereby obtaining toner particles.

[0091] By simultaneously mixing a dispersion of colorant particles during the above mixing, toner particles constituting a color toner can be produced. On the other hand, by not simultaneously mixing a dispersion of colorant particles during the above mixing, toner particles constituting a color toner can be produced.

[0092] Toner particles having a two or more layer structure may be obtained by further adding a polymerization initiator and a polymerizable monomer to the dispersion of the binder resin particles and polymerizing the mixture. Alternatively, binder resin particles having a two or more layer structure may be prepared by emulsion polymerization, and the toner may be produced using the binder resin particles.

[0093] The toner may have a core-shell structure. The toner having the core-shell structure can be produced by a method of producing core particles by associating, aggregating, and fusing core binder resin particles and colorant fine particles, then adding shell binder resin particles for forming a shell layer to a dispersion of the core particles, and aggregating and fusing the shell binder resin particles to the surfaces of the core particles to form a shell layer that covers the surfaces of the core particles.

[0094] The toner according to an embodiment of the present invention can be used as a magnetic or non-magnetic one-component developer, or can be mixed with a carrier to be used as a two-component developer. The carrier may be any known magnetic particle that can be contained in a toner.

[0095] Examples of the magnetic particles include particles containing magnetic materials such as iron, steel, nickel, cobalt, ferrite, and magnetite, as well as alloys of these with aluminum and lead. The carrier may be a coated carrier in which the surface of particles made of the magnetic material is coated with a resin or the like, or a resin-dispersed carrier in which the magnetic material is dispersed in a binder resin. Examples of the coating resin include olefin resin, styrene resin, styrene-acrylic resin, silicone resin, polyester resin, and fluororesin. Examples of the binder resin include acrylic resin, styrene-acrylic resin, polyester resin, fluororesin, and phenolic resin.

[0096] The average particle size of the carrier is preferably 20 μm or more and 100 μm or less, more preferably 25 μm or more and 80 μm or less, in terms of volume-based median diameter (D50). The average particle size of the carrier can be measured, for example, by a laser diffraction particle size distribution analyzer "HELOS" (manufactured by SYMPATEC) equipped with a wet disperser.

[0097] The content of the carrier is preferably 2% by mass or more and 10% by mass or less with respect to the total mass of the toner particles and the carrier.

[0098] [Method of forming a toner image] A toner image forming method according to an embodiment of the present invention can be formed by an electrophotographic image forming method, such as a monochrome image forming method or a full-color image forming method, using the toner produced by the above-mentioned method. Specifically, the toner image forming method includes the steps of (1) forming an electrostatic latent image on the surface of an electrophotographic photosensitive member, (2) developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing the above-mentioned toner to form a toner image, (3) transferring the toner image formed on the surface of the electrophotographic photosensitive member to the surface of a recording medium, and (4) thermally fixing the toner image carried on the surface of the recording medium.

[0099] [Recording Media] The recording medium is a member for holding a toner image. The recording medium is not particularly limited as long as the toner image can be fixed to its surface, and any known medium can be used.

[0100] Examples of the recording medium include copy paper, fine paper, recycled paper, medium-quality paper, wood-burning paper, coated paper, art paper, cast-coated paper, and known plastic films.

[0101] The film includes known plastic films. Examples of the plastic film include biodegradable films such as polyester (PET) film, polyethylene (PE) film, polypropylene (PP) film, nylon (NY) film, polystyrene (PS) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl chloride (PVC) film, polyvinyl alcohol (PVA) film, polyacrylic acid (PAA) film, polycarbonate film, polyacrylonitrile film, and polylactic acid film. The recording medium may be in the form of a sheet having a predetermined size (individually cut), or may be in the form of a continuous sheet that is wound into a roll after a toner image is fixed thereon.

[0102] [Active radiation curing liquid] An actinic ray-curable liquid according to an embodiment of the present invention contains at least an actinic ray-polymerizable compound and a (meth)acrylic resin.

[0103] (Active radiation polymerizable compound) Examples of actinic ray polymerizable compounds include radical polymerizable compounds, cation polymerizable compounds, and mixtures thereof. Among the actinic ray polymerizable compounds, radical polymerizable compounds are preferred. The actinic ray polymerizable compound may be any of a monomer, a polymerizable oligomer, a prepolymer, and a mixture thereof.

[0104] The actinic radiation-polymerizable compound is a compound that crosslinks or polymerizes when irradiated with actinic radiation. Examples of actinic radiation include ultraviolet rays, X-rays, and gamma rays. Among the actinic radiation, ultraviolet rays are preferred.

[0105] A radically polymerizable compound is a compound having an ethylenically unsaturated double bond group in the molecule. The radically polymerizable compound may be a monofunctional or polyfunctional compound. Examples of the radically polymerizable compound include (meth)acrylate, which is an unsaturated carboxylic acid ester compound. In the present invention, "(meth)acrylate" means acrylate or methacrylate, "(meth)acryloyl group" means acryloyl group or methacryloyl group, and "(meth)acrylic" means acrylic or methacrylic.

[0106] Examples of monofunctional (meth)acrylates include isoamyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, benzyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, isomylstyryl (meth)acrylate, isostearyl (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, Examples of the monofunctional (meth)acrylate include methoxypolyethylene glycol (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, and t-butylcyclohexyl (meth)acrylate. The monofunctional (meth)acrylates may be used alone or in combination of two or more.

[0107] Examples of bifunctional and polyfunctional (meth)acrylates include triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene 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, dimethylol-tricyclodecane di(meth)acrylate, PO adduct di(meth)acrylate of bisphenol A, hydroxypivalic acid neopentyl glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, polyethylene These include difunctional (meth)acrylates such as glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate; trifunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate; tri- or higher functional (meth)acrylates such as pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxy tri(meth)acrylate, and pentaerythritol ethoxy tetra(meth)acrylate; oligomers having a (meth)acryloyl group, including polyester acrylate oligomers, and modified products thereof. Examples of the modified compounds include ethylene oxide-modified (EO-modified) (meth)acrylates in which ethylene oxide groups have been inserted, and propylene oxide-modified (PO-modified) (meth)acrylates in which propylene oxide has been inserted. The bifunctional and polyfunctional (meth)acrylates may be used alone or in combination of two or more.

[0108] The cationically polymerizable compound is a compound having a cationically polymerizable group in the molecule. Examples of the cationically polymerizable compound include epoxy compounds, vinyl ether compounds, and oxetane compounds.

[0109] Examples of the epoxy compound include alicyclic epoxy resins such as 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, bis(3,4-epoxycyclohexylmethyl)adipate, vinylcyclohexene monoepoxide, ε-caprolactone-modified 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate, 1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4,1,0]heptane, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexanone-meta-dioxane and bis(2,3-epoxycyclopentyl)ether, diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol, triglyceride of glycerin, and the like. Examples of the epoxy compounds include aliphatic epoxy compounds such as diglycidyl ethers, triglycidyl ethers of trimethylolpropane, diglycidyl ethers of polyethylene glycol, diglycidyl ethers of propylene glycol, polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides (such as ethylene oxide and propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin, as well as aromatic epoxy compounds such as di- or polyglycidyl ethers of bisphenol A or its alkylene oxide adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or its alkylene oxide adducts, and novolac-type epoxy resins.

[0110] Examples of the vinyl ether compound 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; and di- or trivinyl 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.

[0111] Examples of the oxetane compound include 3-hydroxymethyl-3-methyloxetane, 3-hydroxymethyl-3-ethyloxetane, 3-hydroxymethyl-3-propyloxetane, 3-hydroxymethyl-3-n-butyloxetane, 3-hydroxymethyl-3-phenyloxetane, 3-hydroxymethyl-3-benzyloxetane, 3-hydroxyethyl-3-methyloxetane, 3-hydroxyethyl-3-ethyloxetane, 3-hydroxyethyl-3-propyloxetane, 3-hydroxyethyl 3-phenyloxetane, 3-hydroxypropyl-3-methyloxetane, 3-hydroxypropyl-3-ethyloxetane, 3-hydroxypropyl-3-propyloxetane, 3-hydroxypropyl-3-phenyloxetane, 3-hydroxybutyl-3-methyloxetane, 1,4 bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and di[1-ethyl(3-oxetanyl)]methyl ether.

[0112] Among the actinic ray polymerizable compounds, it is preferable to include a radical polymerizable compound, and among the radical polymerizable compounds, it is more preferable to include a (meth)acrylate.

[0113] (Polymerization initiator) The actinic ray-curable liquid according to one embodiment of the present invention may contain a polymerization initiator. The polymerization initiator may be any initiator capable of initiating polymerization of the actinic ray-polymerizable compound upon irradiation with actinic rays. For example, when the actinic ray-curable ink contains a radically polymerizable compound, the polymerization initiator may be a photoradical initiator. When the actinic ray-curable ink contains a cationically polymerizable compound, the polymerization initiator may be a photocationic initiator (photoacid generator).

[0114] The radical polymerization initiator includes an intramolecular bond cleavage type radical polymerization initiator and an intramolecular hydrogen abstraction type radical polymerization initiator.

[0115] Examples of the intramolecular bond cleavage type radical polymerization initiator include acetophenone-based initiators such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-methylthiophenyl)propan-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; benzoins such as benzoin methyl ether and benzoin isopropyl ether; acylphosphine oxide-based initiators such as 2,4,6-trimethylbenzoindiphenylphosphine oxide; and benzyl and methylphenyl glyoxyesters.

[0116] Examples of the intramolecular hydrogen abstraction type radical polymerization initiator include benzophenone-based initiators such as benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone-based initiators such as 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone; aminobenzophenone-based initiators such as Michler's ketone and 4,4'-diethylaminobenzophenone; 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, and camphorquinone.

[0117] Examples of cationic polymerization initiators include photoacid generators, such as aromatic onium compounds B(C6F5)4, including diazonium, ammonium, iodonium, sulfonium, and phosphonium. - , PF6 - , AsF6 - , SbF6 - , CF3SO3 - These include salts, sulfonates that generate sulfonic acid, halides that photogenerate hydrogen halide, and iron-allene complexes.

[0118] ((Meth)acrylic resin) The actinic ray-curable liquid according to one embodiment of the present invention contains a (meth)acrylic resin. The (meth)acrylic resin is not particularly limited, and may be a resin obtained by polymerizing a (meth)acrylic acid ester monomer using a known method, or a commercially available product. By including a resin in the actinic ray-curable liquid, the reaction rate of the actinic ray-polymerizable compound can be reduced, suppressing cure shrinkage. This can prevent the actinic ray-curable liquid from peeling off from the toner image due to excessive shrinkage of the actinic ray-curable liquid during curing. This can improve the adhesion of the cured actinic ray-curable liquid to the toner image. Furthermore, the components constituting the (meth)acrylic resin have a structure similar to that of the actinic ray-polymerizable compound contained in the toner, thereby increasing the affinity between the actinic ray-curable liquid and the toner, thereby improving the adhesion of the actinic ray-curable liquid to the toner image. Furthermore, by including a (meth)acrylic resin, the viscosity of the actinic ray-curable liquid can be increased, thereby improving application properties.

[0119] Examples of the (meth)acrylic acid ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, phenyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and derivatives thereof.

[0120] The (meth)acrylic resin may be copolymerized with styrene. The copolymerized styrene increases the affinity between the (meth)acrylic resin and the binder resin of the toner image, which also contains styrene as a constituent, and improves the adhesion between the toner image and the actinic radiation-curable liquid. When styrene is copolymerized, the copolymerization ratio of styrene is preferably 10% or more and 90% or less, and more preferably 30% or more and 80% or less.

[0121] The content of the (meth)acrylic resin is preferably 2% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, based on the total mass of the actinic ray-curable liquid. By making the content of the (meth)acrylic resin 2% by mass or more, it is possible to suppress the occurrence of cure shrinkage. Furthermore, by making it 20% by mass or less, it is possible to prevent a decrease in the curing rate and suppress curing defects.

[0122] The weight average molecular weight (Mw) of the (meth)acrylic resin is preferably 3,000 or more and 40,000 or less, and more preferably 5,000 or more and 30,000 or less. When the weight average molecular weight (Mw) of the (meth)acrylic resin is 3,000 or more, the hardness of the coating film obtained by curing the actinic ray-curable liquid can be increased, and when it is 40,000 or less, a decrease in solubility in actinic ray-polymerizable compounds can be suppressed. The weight average molecular weight (Mw) of the (meth)acrylic resin can be measured, for example, using the above-mentioned GPC apparatus.

[0123] Furthermore, the surface tension of the actinic ray-curable liquid before irradiation with actinic rays is preferably 10 mN / m or more and 40 mN / m or less, and more preferably 10 mN / m or more and 30 mN / m or less. By adjusting the surface tension of the actinic ray-curable liquid to 40 mN / m or less, the coatability of the liquid to the toner image can be improved.

[0124] Furthermore, the surface tension of the coating film (solid) formed by curing the actinic ray-curable liquid after irradiation with actinic rays is preferably 30 mN / m or more, and more preferably 40 mN / m or more. When the surface tension of the coating film formed by curing the actinic ray-curable liquid after irradiation with actinic rays is 30 mN / m or more, the adhesion to the toner image is further improved.

[0125] The surface tension can be determined by the pendant drop method using, for example, a contact angle meter "DMs-701" (manufactured by Kyowa Interface Science Co., Ltd.) Specifically, the actinic ray-curable liquid is placed in a syringe needle, and the shapes of droplets of the actinic ray-curable liquid dropped at 23°C are measured five times, and the average value is determined.

[0126] Furthermore, the viscosity of the actinic ray-curable liquid before irradiation with actinic rays is preferably 200 mPa·s or more and 1000 mPa·s or less at 25°C, and more preferably 200 mPa·s or more and 700 mPa·s or less. When the viscosity of the actinic ray-curable liquid is 200 mPa·s or more, the formation of pinholes due to the actinic ray-curable liquid being repelled by the actinic ray-curable liquid applied to the surface of the toner image can be suppressed. When the viscosity is 1000 mPa·s or less, poor leveling can be suppressed, and the occurrence of streak-like noise can be suppressed. The viscosity of the actinic ray-curable liquid at 25°C can be measured, for example, using a vibration viscometer "FVM70A-STC" (manufactured by Sekonic Corporation).

[0127] (surface tension adjuster) The actinic radiation-curable liquid according to one embodiment of the present invention preferably contains a surface tension modifier. The surface tension modifier is not particularly limited, and any known surface tension modifier can be used. Examples of the surface tension modifier include anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, and fatty acid salts; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, and polyoxyethylene-polyoxypropylene block copolymers; cationic surfactants such as alkylamine salts and quaternary ammonium salts; and silicone-based and fluorine-based surfactants. The surface tension modifiers may be used alone or in combination.

[0128] The content of the surfactant is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 5% by mass or less, based on the total mass of the actinic ray-curable liquid.

[0129] (Other ingredients) In addition to the above components, the actinic ray-curable liquid may contain, as necessary, polysaccharides, viscosity modifiers, resistivity modifiers, film-forming agents, ultraviolet absorbers, antioxidants, antifungal agents, anticorrosive agents, etc.

[0130] An actinic radiation-curable liquid can be obtained by mixing the actinic radiation-polymerizable compound, polymerization initiator, and acrylic resin. Specifically, the actinic radiation-polymerizable compound is placed in a reaction vessel, followed by the acrylic resin, and the mixture is stirred with a magnetic stirrer at 23°C to dissolve the acrylic resin. After the acrylic resin is dissolved, a polymerization initiator is added to obtain an actinic radiation-curable liquid.

[0131] In addition, the minimum SP value among the SP values ​​of the multiple monomers that make up the styrene-acrylic resin is defined as SPa min (J / cm 3 ) 1 / 2 The smallest SP value among the SP values ​​of the monomers constituting the (meth)acrylic resin is defined as SPb min (J / cm 3 ) 1 / 2 When the above SPa min and the above SPb min It is preferable that and satisfy the condition of the following mathematical formula (1).

[0132]

number

[0133] The minimum SP value (SPa min ) and the minimum SP value (SPb min ) and the difference (|SPa min -SPb min |) is 0.5 (J / cm 3 ) 1 / 2 It is preferable that the concentration is 0 (J / cm 3 ) 1 / 2 More than 0.5(J / cm 3 ) 1 / 2 It is more preferable that the above |SPamin -SPb min | is 0.5 (J / cm 3 ) 1 / 2 If the SP value is less than this, the monomers constituting the styrene-acrylic resin and the monomers constituting the actinic ray-curable liquid are close to each other, and therefore when the actinic ray-curable liquid is applied to the surface of the toner image, they are compatible with each other and wet and spread, allowing the liquid to be applied evenly.

[0134] The SP values ​​of the monomers constituting the styrene-acrylic resin and the actinic radiation-curable liquid (described below) can be theoretically calculated from the cohesive energy and molar volume of the atoms and atomic groups based on the Fedors constant, specifically using the following formula (2):

[0135]

number

[0136] The styrene-acrylic resin contained in the binder resin according to one embodiment of the present invention and the (meth)acrylic resin contained in the actinic ray-curable liquid (described later) preferably contain the same monomer as a constituent component, which can improve the adhesion between the actinic ray-curable liquid irradiated with actinic rays and the toner image and recording medium.

[0137] The same monomer contained in the styrene-acrylic resin and the actinic radiation-curable liquid (described below) is preferably selected from the group consisting of styrene, acrylic acid, methyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate, and 2-ethylhexyl methacrylate, and more preferably selected from the group consisting of styrene, methyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. Of the above monomers, 2-ethylhexyl acrylate is preferred.

[0138] Adhesion can be improved by using 2-ethylhexyl acrylate as the same monomer contained in the styrene-acrylic resin and the actinic radiation-curable liquid. This is thought to be due to the branched structure of the 2-ethylhexyl acrylate.

[0139] [Method of applying actinic radiation curable liquid] The method for applying the actinic ray curable liquid to the surface of the toner image is not particularly limited, and any known method for applying a liquid can be used.

[0140] Examples of methods for applying the actinic radiation-curable liquid include liquid film coating devices such as roll coaters, flexo coaters, rod coaters, blades, wire bars, air knives, curtain coaters, slide coaters, doctor knives, screen coaters, gravure coaters (e.g., offset gravure coaters), slot coaters, extrusion coaters, and inkjet coaters. Such devices can be used in well-known ways, such as forward and reverse roll coating, offset gravure, curtain coating, lithographic coating, screen coating, gravure coating, and inkjet coating.

[0141] 1-2. Step of curing actinic radiation curable liquid The step of curing the actinic ray-curable liquid according to one embodiment of the present invention is a step of irradiating the actinic ray-curable liquid applied to the surface of the toner image with actinic rays to cure the actinic ray-curable liquid.

[0142] The light source for irradiating the actinic ray curable liquid applied to the surface of the toner image with actinic rays is not particularly limited, and any known light source can be used.

[0143] Examples of light sources for irradiating the actinic ray-curable liquid with actinic rays include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, carbon arc lamps, metal halide lamps, fluorescent lamps, tungsten lamps, light-emitting diodes (LEDs), etc. Among the above light sources, metal halide lamps are preferred.

[0144] The cumulative amount of actinic radiation (e.g., ultraviolet light) irradiated is 5 mJ / cm 2 More than 200mJ / cm 2 It is preferable that the integrated light amount is 5 mJ / cm 2 When the cumulative light amount is 200 mJ / cm or more, the actinic ray polymerizable compound contained in the actinic ray curable liquid can be sufficiently polymerized and crosslinked. 2 If the temperature is below this range, the recording medium (for example, paper) and toner can be prevented from being excessively heated, and sufficient quality can be ensured.

[0145] Furthermore, the amount of cure shrinkage of the actinic ray-curable liquid irradiated with actinic rays is preferably 20 mm or less, more preferably 0 mm or more and 20 mm or less, and even more preferably 0 mm or more and 15 mm or less. When the amount of cure shrinkage is 20 mm or less, adhesion to the toner image can be improved. The amount of cure shrinkage can be determined, for example, by applying the actinic ray-curable liquid to the surface of a PET film, irradiating the surface with actinic rays, and measuring the warpage at the four corners of the PET film after the actinic ray irradiation with a ruler.

[0146] 1-3.Other processes After these steps are performed, untransferred toner particles remaining on the surfaces of the electrophotographic photosensitive member, intermediate transfer member, etc. may be removed by, for example, scraping the surfaces of the electrophotographic photosensitive member, intermediate transfer member, etc. with a blade.

[0147] Furthermore, the image forming method according to one embodiment of the present invention may include a step of forming a toner image and a step of fixing the formed toner image on a recording medium before the step of applying an actinic ray-curable liquid to the surface of the toner image.

[0148] 2. Image forming equipment The image forming apparatus 1 according to the embodiment of the present invention includes an image reading section 110, an image processing section 30, an image forming section 40, a paper conveying section 50, and a fixing device 60.

[0149] Image forming section 40 has image forming units 41Y, 41M, 41C, and 41K that form images using toner of each color: Y (yellow), M (magenta), C (cyan), and K (black). These units all have the same configuration except for the toner they contain, so hereinafter, the symbols representing the colors may be omitted. Image forming section 40 also has an intermediate transfer unit 42 and a secondary transfer unit 43. These correspond to transfer devices.

[0150] Image forming unit 41 includes exposure device 411, development device 412, photosensitive drum 413, charging device 414, and drum cleaning device 415. Photosensitive drum 413 is, for example, a negatively charged organic photosensitive member. The surface of photosensitive drum 413 is photoconductive. Photosensitive drum 413 corresponds to a photosensitive member. Charging device 414 is, for example, a corona charger. Charging device 414 may also be a contact charging device that charges photosensitive drum 413 by bringing a contact charging member such as a charging roller, charging brush, or charging blade into contact with photosensitive drum 413. Exposure device 411 includes, for example, a semiconductor laser as a light source and an optical deflection device (polygon motor) that irradiates photosensitive drum 413 with laser light corresponding to the image to be formed.

[0151] Developing device 412 is a two-component developing device. Developing device 412 has, for example, a developing container that contains a two-component developer, a developing roller (magnetic roller) that is rotatably arranged at the opening of the developing container, a partition that separates the inside of the developing container so that the two-component developer can communicate with each other, a transport roller that transports the two-component developer on the opening side of the developing container toward the developing roller, and a stirring roller that stirs the two-component developer in the developing container. The developing container contains the toner as the two-component developer.

[0152] Intermediate transfer unit 42 has intermediate transfer belt 421, primary transfer roller 422 that presses intermediate transfer belt 421 against photosensitive drum 413, multiple support rollers 423 including backup roller 423A, and belt cleaning device 426. Intermediate transfer belt 421 is loop-tensioned around multiple support rollers 423. By rotating at least one drive roller among the multiple support rollers 423, intermediate transfer belt 421 runs at a constant speed in the direction of arrow A.

[0153] The secondary transfer unit 43 has an endless secondary transfer belt 432 and a plurality of support rollers 431 including a secondary transfer roller 431A. The secondary transfer belt 432 is stretched by the secondary transfer roller 431A and the support rollers 431 in a loop shape.

[0154] Fixing device 60 has, for example, a fixing roller 62, an endless heat-generating belt 63 that covers the outer peripheral surface of fixing roller 62 and heats and melts the toner that forms the toner image on paper S, and a pressure roller 64 that presses paper S against fixing roller 62 and heat-generating belt 63. Paper S corresponds to a recording medium.

[0155] Image forming apparatus 1 further includes an image reading unit 110, an image processing unit 30, and a paper transport unit 50. Image reading unit 110 includes a paper feeder 111 and a scanner 112. Paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, and a transport path unit 53. Three paper feed tray units 51a, 51b, and 51c that make up paper feed unit 51 store paper S (standard paper, special paper) identified based on basis weight, size, etc., by pre-set type. Transport path unit 53 includes multiple transport roller pairs, such as registration roller pair 53a.

[0156] The formation of an image by the image forming apparatus 1 will be described.

[0157] The scanner 112 optically scans and reads the document D on the contact glass. The light reflected from the document D is read by the CCD sensor 112a and becomes input image data. The input image data is subjected to predetermined image processing in the image processing unit 30 and sent to the exposure device 411.

[0158] Photoconductor drum 413 rotates at a constant peripheral speed. Charging device 414 uniformly charges the surface of photoconductor drum 413 to a negative polarity. In exposure device 411, a polygon mirror of a polygon motor rotates at high speed, and laser light corresponding to input image data for each color component is developed along the axial direction of photoconductor drum 413 and irradiated onto the outer circumferential surface of photoconductor drum 413 along the axial direction. In this way, an electrostatic latent image is formed on the surface of photoconductor drum 413.

[0159] In developing device 412, the toner particles are charged by stirring and transporting the two-component developer in the developer container, and the two-component developer is transported to the developing roller, forming a magnetic brush on the surface of the developing roller. The charged toner particles electrostatically adhere from the magnetic brush to the electrostatic latent image on photosensitive drum 413. In this way, the electrostatic latent image on the surface of photosensitive drum 413 is visualized, and a toner image corresponding to the electrostatic latent image is formed on the surface of photosensitive drum 413. As the toner is transported, it is stirred in the developer container and subjected to stress associated with this stirring, but because the toner has excellent crush resistance, the toner is not crushed during transport.

[0160] The toner image on the surface of the photosensitive drum 413 is transferred to an intermediate transfer belt 421 by an intermediate transfer unit 42. Any residual toner remaining on the surface of the photosensitive drum 413 after transfer is removed by a drum cleaning device 415 having a drum cleaning blade that comes into sliding contact with the surface of the photosensitive drum 413.

[0161] The primary transfer roller 422 presses the intermediate transfer belt 421 against the photosensitive drum 413, thereby forming a primary transfer nip for each photosensitive drum between the photosensitive drum 413 and the intermediate transfer belt 421. In the primary transfer nip, toner images of each color are transferred onto the intermediate transfer belt 421 in order, superimposed on one another.

[0162] Meanwhile, secondary transfer roller 431A is pressed against backup roller 423A via intermediate transfer belt 421 and secondary transfer belt 432. As a result, a secondary transfer nip is formed by intermediate transfer belt 421 and secondary transfer belt 432. Paper S is transported to the secondary transfer nip by paper transport unit 50, and paper S passes through the secondary transfer nip. Correction of skew of paper S and adjustment of transport timing are performed by a registration roller unit in which registration roller pair 53a is arranged.

[0163] When the paper S is transported to the secondary transfer nip, a transfer bias is applied to the secondary transfer roller 431A. By applying this transfer bias, the toner image carried on the intermediate transfer belt 421 is transferred onto the paper S. The paper S onto which the toner image has been transferred is transported by the secondary transfer belt 432 towards the fixing device 60.

[0164] The fixing device 60 forms a fixing nip with a heat-generating belt 63 and a pressure roller 64, and heats and presses the conveyed paper S at the fixing nip. The toner particles constituting the toner image on the paper S are heated, and the crystalline resin therein quickly melts. Furthermore, the presence of the modified silicone oil in the toner particles significantly enhances compatibility between the binder resin melted by heating and the modified silicone oil, plasticizing the binder resin and reducing the thermal properties of the toner. As a result, the entire toner particles quickly melt with a relatively small amount of heat, and the toner components adhere to the paper S. Furthermore, in the adhered molten toner components, the crystalline polyester polymer segments in the hybrid crystalline resin quickly crystallize, quickly solidifying the entire molten toner components. In this way, the toner image is quickly fixed to the paper S with a relatively small amount of heat. The paper S with the fused toner image is then discharged from the printer by the paper discharge section 52, which includes a paper discharge roller 52a.

[0165] After the secondary transfer, residual toner remaining on the surface of the intermediate transfer belt 421 is removed by a belt cleaning device 426 having a belt cleaning blade that is brought into sliding contact with the surface of the intermediate transfer belt 421 .

[0166] The paper S on which the toner image has been fixed and discharged to the outside of the machine by the paper discharge unit 52 is transported to a varnish applicator (not shown), where an actinic ray curable liquid is applied to the surface of the toner image so that the applied thickness is about 5 μm. 2 More than 200J / cm 2 By irradiating the liquid with actinic radiation (for example, ultraviolet radiation) so that the liquid hardens, the surface of the toner image is coated with the actinic radiation-hardening liquid. This results in the formation of a high-quality, highly durable image. [Example]

[0167] 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.

[0168] [Preparation of amorphous vinyl resin dispersion X1] (First stage polymerization) A 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introducing device was charged with 8 parts by mass of sodium dodecyl sulfate and 3,000 parts by mass of ion-exchanged water, and the internal temperature of the reaction vessel was raised to 80°C while stirring at a stirring speed of 230 rpm under a nitrogen stream. After the temperature was raised, an aqueous solution prepared by dissolving 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added to the resulting mixture, and the temperature of the resulting mixture was again raised to 80°C. A monomer mixture 1 having the following composition was added dropwise to the mixture over 1 hour, and the mixture was then heated and stirred at 80°C for 2 hours to polymerize, thereby preparing a resin particle dispersion a1. (Monomer mixture 1) Styrene 480 parts by mass Methyl acrylate 250 parts by mass Methacrylic acid 68 parts by mass

[0169] (Second stage polymerization) A 5L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen inlet was charged with a solution of 7 parts by weight of sodium polyoxyethylene (2) dodecyl ether sulfate dissolved in 3,000 parts by weight of ion-exchanged water. After heating the solution to 80°C, 80 parts by weight of resin particle dispersion a1 (solids equivalent) and monomer mixture 2 (composed as shown below) were added. The mixture was mixed and dispersed for 1 hour using a mechanical disperser equipped with a circulation path, "CLEARMIX" (manufactured by M-Technique Co., Ltd.; "CLEARMIX" is a registered trademark of the company), to prepare a dispersion containing emulsified particles (oil droplets). Note that behenyl behenate (shown below) is a release agent with a melting point of 73°C. (Monomer mixture 2) Styrene 285 parts by mass Methyl acrylate 95 parts by mass Methacrylic acid 20 parts by mass Behenyl behenate 190 parts by mass

[0170] Next, an initiator solution prepared by dissolving 6 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added to the above dispersion, and the resulting dispersion was polymerized by heating and stirring at 84°C for 1 hour to prepare resin particle dispersion a2.

[0171] (Third stage polymerization) 400 parts by mass of ion-exchanged water was added to dispersion a2 of resin particles obtained by the second-stage polymerization and mixed thoroughly. Then, a solution of 11 parts by mass of potassium persulfate dissolved in 400 parts by mass of ion-exchanged water was added to the resulting dispersion, and monomer mixture 3 having the following composition was added dropwise over one hour at a temperature of 82°C. After the dropwise addition was completed, the dispersion was heated and stirred for two hours to polymerize, and then cooled to 28°C to prepare amorphous vinyl resin dispersion X1 consisting of a vinyl resin (styrene-acrylic resin). (Monomer mixture 3) Styrene 307 parts by mass Methyl acrylate 147 parts by mass Methacrylic acid 52 parts by mass

[0172] The physical properties of the obtained amorphous vinyl resin dispersion X1 were measured, and it was found that the volume-based median diameter (d50) was 220 nm, the glass transition temperature (Tg) was 46°C, and the weight average molecular weight (Mw) was 32,000.

[0173] The median diameter (d50) was measured using a Microtrac particle size distribution analyzer "UPA-150" (manufactured by Nikkiso Co., Ltd.), the glass transition temperature (Tg) was measured using a thermal analyzer "Diamond DSC" (manufactured by PerkinElmer), and the weight average molecular weight (Mw) was measured using a GPC apparatus "HLC-8120GPC" (manufactured by Tosoh Corporation).

[0174] [Preparation of amorphous vinyl resin dispersion X2] Amorphous vinyl resin dispersion X2 was obtained in the same manner as in the preparation of amorphous vinyl resin dispersion X1, except that methyl acrylate was changed to n-butyl acrylate.

[0175] [Preparation of amorphous vinyl resin dispersion X3] Amorphous vinyl resin dispersion X3 was obtained in the same manner as amorphous vinyl resin dispersion X2, except that 30% of the n-butyl acrylate content in amorphous vinyl resin dispersion X2 was changed to 2-ethylhexyl acrylate.

[0176] [Synthesis of aromatic polyester resin b1] The raw material monomers for the following addition polymerization resin (styrene-acrylic resin) unit, including a bireactive monomer, and a radical polymerization initiator were placed in a dropping funnel. (raw material monomer and radical polymerization initiator) Styrene 80 parts by mass n-Butyl acrylate 20 parts by mass Acrylic acid 10 parts by mass Polymerization initiator (di-t-butyl peroxide) 16 parts by mass

[0177] Furthermore, the raw material monomers for the aromatic polyester resin unit shown below were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve them. (raw material monomer) Bisphenol A propylene oxide 2 mole adduct 285.7 parts by mass Terephthalic acid 66.9 parts by mass Fumaric acid 47.4 parts by mass

[0178] Next, the raw material monomer for the addition polymerization resin was added dropwise over 90 minutes with stirring. After aging for 60 minutes, the unreacted raw material monomer for the addition polymerization resin was removed under reduced pressure (8 kPa). Then, 0.4 parts by mass of Ti(OBu)4 was added as an esterification catalyst, and the mixture was heated to 235°C. The reaction was carried out at normal pressure (101.3 kPa) for 5 hours and then at reduced pressure (8 kPa) for 1 hour. The mixture was then cooled to 200°C and then reacted under reduced pressure (20 kPa) until the desired softening point was reached. The solvent was then removed to obtain aromatic polyester resin b1 for the shell. The resulting aromatic polyester resin b1 for the shell had a glass transition temperature (Tg) of 60°C, a weight average molecular weight (Mw) of 30,000, and an acid value of 16 mgKOH / g.

[0179] [Aromatic polyester resin dispersion B1] 100 parts by weight of the aromatic polyester resin b1 for the shell was dissolved in 400 parts by weight of ethyl acetate (Kanto Chemical Co., Ltd.), mixed with 638 parts by weight of a previously prepared 0.26% by weight sodium lauryl sulfate solution, and then ultrasonically dispersed for 30 minutes at V-LEVEL 300μA using an ultrasonic homogenizer "US-150T" (manufactured by Nippon Seiki Seisakusho) while stirring. After that, the ethyl acetate was completely removed while stirring under reduced pressure for 3 hours using a diaphragm vacuum pump "V-700" (manufactured by BUCHI) at a heated temperature of 40 ° C. A 13.5% by weight solids shell aromatic polyester resin dispersion B1 was prepared. At this time, the particles contained in the obtained aromatic polyester resin B1 for the shell had a volume-based median diameter of 160 nm.

[0180] The number average molecular weight (Mn) and weight average molecular weight (Mw) of the aromatic polyester resin were measured using a GPC device "HLC-8120GPC," the glass transition temperature (Tg) was measured using a thermal analyzer "Diamond DSC," and the acid value was determined in accordance with JIS K0070 (1992). "Carboxy groups contained in the polyester resin" refers to the amount of residual carboxyl groups that did not react with hydroxy groups in the condensation polymerization reaction when synthesizing the aromatic polyester resin.

[0181] [Synthesis of aliphatic polyester resin c1] A 5L reactor equipped with a stirrer, temperature sensor, condenser, and nitrogen supply was charged with 300 parts by weight of sebacic acid (a polycarboxylic acid) and 170 parts by weight of 1,6-hexanediol (a polyhydric alcohol). The internal temperature was raised to 190°C over 1 hour with stirring. After confirming uniform stirring, Ti(OBu)4 was added as a catalyst in an amount of 0.003% by weight relative to the amount of sebacic acid charged. The internal temperature was raised from 190°C to 240°C over 6 hours while distilling off the resulting water. The dehydration condensation reaction was continued for 6 hours at 240°C to produce an aliphatic polyester resin. The melting point (Tm) of this aliphatic polyester resin was 66.8°C and the number average molecular weight (Mn) was 6300. The weight average molecular weight (Mw) and number average molecular weight (Mn) of the aliphatic polyester resin c1 were measured using a GPC device "HLC-8120GPC", and the melting point (Tm) was measured using a thermal analysis device "Diamond DSC".

[0182] [Preparation of Aliphatic Polyester Particle Dispersion C1] A 3-liter jacketed reactor "BJ-30N" (manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a condenser, thermometer, water dripper, and anchor blades was charged with 300 parts by weight of aliphatic polyester resin c1, 160 parts by weight of methyl ethyl ketone (solvent), and 100 parts by weight of isopropyl alcohol (solvent). The aliphatic polyester resin was dissolved by stirring at 100 rpm while maintaining the temperature at 70 ° C in a water-circulating thermostatic bath. Next, the stirring speed was increased to 150 rpm, the water-circulating thermostatic bath was set to 66 ° C, and 17 parts by weight of 10% ammonia water (reagent) was added over 10 minutes. After that, a total of 900 parts by weight of ion-exchanged water maintained at 66 ° C was added dropwise at a rate of 7 parts by weight / min to cause phase inversion, resulting in an emulsion.

[0183] 800 parts by mass of the above emulsion and 700 parts by mass of ion-exchanged water were placed in a 2-liter recovery flask and placed in an evaporator (manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a vacuum control unit via a trap bulb. The recovery flask was heated in a 60°C hot water bath while rotating, and the pressure was reduced to 7 kPa while taking care to prevent bumping, to remove the solvent. When the amount of recovered solvent reached 1,100 parts by mass, the pressure was returned to normal, and the recovery flask was water-cooled to obtain an aliphatic polyester particle dispersion. The resulting dispersion had no solvent odor. The volume-based median diameter (D50) of the aliphatic polyester resin particles in this dispersion was 130 nm. Ion-exchanged water was then added to adjust the solids concentration to 20% by mass, yielding aliphatic polyester resin dispersion C1. The median diameter (d50) was measured using a Microtrac particle size distribution analyzer "UPA-150" (manufactured by Nikkiso Co., Ltd.).

[0184] [Preparation of colorant dispersion] 90 parts by weight of sodium dodecyl sulfate was added to 1600 parts by weight of ion-exchanged water. While stirring this solution, 420 parts by weight of copper phthalocyanine (CI Pigment Blue 15:3) was gradually added, and then the mixture was dispersed using a stirring device "Clearmix" (M Technique Co., Ltd.) to prepare a colorant dispersion. The volume-based median diameter (d50) of the colorant particles in the resulting colorant dispersion was 110 nm. The median diameter (d50) was measured using a Microtrac particle size distribution analyzer "UPA-150."

[0185] [Production of Cyan Toner 1] A reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube was charged with 315 parts by mass of amorphous vinyl resin dispersion X1 (solids content), 30 parts by mass of aliphatic polyester resin dispersion C1 (solids content), 1% by mass of dodecyl diphenyl ether disulfonic acid sodium salt (solids content) in terms of resin ratio, and 2000 parts by mass of ion-exchanged water. Then, a 5 mol / L aqueous sodium hydroxide solution was further added to adjust the pH of the dispersion in the reaction vessel to 10 (measurement temperature 25°C), and 30 parts by mass of colorant dispersion (solids content) was charged to the dispersion.

[0186] Next, an aqueous solution of 30 parts by weight of magnesium chloride dissolved in 30 parts by weight of ion-exchanged water was added to the reaction vessel over 10 minutes at 30°C while stirring. The resulting mixture was heated to 80°C, and 40 parts by weight of crystalline dispersion Y (solids content equivalent) was added to the mixture over 10 minutes to cause flocculation. The particle size of the particles associated in the mixture was measured using a Coulter Multisizer 3 (Beckman Coulter, Inc.), and the particles were allowed to grow until their volume-based median diameter (d50) reached 6.0 μm. When the supernatant of the resulting reaction solution became clear, an aqueous solution of 190 parts by weight of sodium chloride dissolved in 760 parts by weight of ion-exchanged water was added to the reaction solution to stop particle growth.

[0187] Furthermore, the reaction solution was heated to 80°C and stirred to promote particle fusion. The particles in the reaction solution were measured using the measuring device "FPIA-3000" (HPF detection number: 4000 particles). When the average circularity of the particles reached 0.965, the reaction solution was cooled to 30°C at a cooling rate of 2.5°C / min.

[0188] The dispersion of toner base particles produced in the aggregation and fusion process was subjected to solid-liquid separation using a basket centrifuge to form a wet cake of toner base particles. This wet cake was washed with 35°C ion-exchanged water and then adjusted with a 25% aqueous sodium hydroxide solution until the pH reached 4.0 (equivalent to a net strength of 0.10). The filtrate was washed with 35°C ion-exchanged water until the electrical conductivity of the filtrate reached 5 μS / cm, and then transferred to a "Flash Jet Dryer (manufactured by Seishin Enterprise Co., Ltd.)" and dried until the moisture content reached 0.5% by mass to obtain toner base particles 1.

[0189] To 100 parts by mass of toner base particles 1, 0.6 parts by mass of hydrophobic silica (number average primary particle diameter = 12 nm, hydrophobicity = 68) and 1.0 part by mass of hydrophobic titanium oxide (number average primary particle diameter = 20 nm, hydrophobicity = 63) were added, and these were mixed in a "Henschel Mixer" (manufactured by Nippon Coke and Engineering Co., Ltd.) at a rotor peripheral speed of 35 mm / sec and 32°C for 20 minutes, after which coarse particles were removed using a sieve with 45 μm openings. This external additive treatment produced cyan toner 1, which is an aggregate of toner base particles 1.

[0190] The average circularity is a value calculated by taking images using an "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement conditions of HPF (high magnification imaging) mode, calculating the circularity of each toner particle according to the following formula, adding up the circularity of each toner particle, and dividing by the total number of toner particles. If the HPF detection number is within the above range, reproducibility can be obtained. Formula: Circularity = (perimeter of a circle with the same projected area as the particle image) / (perimeter of the particle's projected image)

[0191] Here, the average circularity in this example is measured for the toner aqueous dispersion before the cleaning step, but it was confirmed that the same value can be obtained when measuring the toner after the addition of external additives.

[0192] [Production of Cyan Toner 2] Cyan toner 2 was produced in the same manner as cyan toner 1, except that amorphous vinyl resin dispersion X1 was changed to amorphous vinyl resin dispersion X2.

[0193] [Production of Cyan Toner 3] Cyan toner 3 was produced in the same manner as cyan toner 1, except that amorphous vinyl resin dispersion X1 was changed to amorphous vinyl resin dispersion X3.

[0194] [Manufacturing of Cyan Toner 4] A reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube was charged with 315 parts by mass of amorphous vinyl resin dispersion X3 (solids content equivalent), 30 parts by mass of aliphatic polyester resin dispersion C1 (solids content equivalent), 1% by mass of dodecyl diphenyl ether disulfonic acid sodium salt (solids content equivalent) in terms of resin ratio, and 2000 parts by mass of ion-exchanged water. Then, a 5 mol / L aqueous sodium hydroxide solution was further added to adjust the pH of the dispersion in the reaction vessel to 10 (measurement temperature 25°C), and 30 parts by mass of colorant dispersion (solids content equivalent) was charged to the above dispersion.

[0195] Next, an aqueous solution of 60 parts by weight of magnesium chloride dissolved in 60 parts by weight of ion-exchanged water was added to the reaction vessel over 10 minutes while stirring at 30°C. The resulting mixture was allowed to stand for 3 minutes, then the temperature was raised to 80°C over 60 minutes. After reaching 80°C, the mixture was allowed to stand for 30 minutes. After that, the particle size of the particles associated in the mixture was measured using a Coulter Multisizer 3 (manufactured by Beckman Coulter) while adjusting the stirring speed so that the particle size growth rate was 0.01 μm / min. The particles were allowed to grow until their volume-based median diameter (d50) reached 6.0 μm.

[0196] Thereafter, 60 parts by mass of aromatic polyester resin dispersion B1 (solid content equivalent) for the shell was added over 30 minutes, and when the supernatant of the reaction solution became transparent, an aqueous solution in which 190 parts by mass of sodium chloride was dissolved in 760 parts by mass of ion-exchanged water was added to stop particle growth.

[0197] The temperature was further increased and the particles were heated and stirred at 90°C to promote fusion of the particles, and when the average circularity reached 0.970 using an "FPIA-3000" toner average circularity measuring device (HPF detection number: 4000), the reaction solution was cooled to 30°C at a cooling rate of 2.5°C / min. Next, solid-liquid separation was performed, and the dehydrated toner cake was redispersed in ion-exchanged water and washed by repeating this solid-liquid separation operation three times, and then dried at 40°C for 24 hours to obtain toner base particles 2.

[0198] The average circularity of the particles was determined in the same manner as in the case of cyan toner 1.

[0199] To 100 parts by mass of toner base particles 2, 0.6 parts by mass of hydrophobic silica (number average primary particle diameter = 12 nm, hydrophobicity = 68) and 1 part by mass of hydrophobic titanium oxide (number average primary particle diameter = 20 nm, hydrophobicity = 63) were added, and these were mixed in a "Henschel Mixer" (manufactured by Nippon Coke & Engineering Co., Ltd.) at a rotor peripheral speed of 35 mm / sec and 32°C for 20 minutes, after which coarse particles were removed using a sieve with 45 μm openings. This external additive treatment produced cyan toner 4, which is an aggregate of toner base particles 2.

[0200] [Preparation of actinic radiation curable liquid 1] A reaction vessel equipped with a stirrer was charged with 90 parts by mass of 1,6-hexanediol diacrylate, 10 parts by mass of trimethylolpropane triacrylate, 1 part by mass of benzophenone, 0.2 parts by weight of the fluorosurfactant Surflon S611 (0.5 parts by mass, manufactured by AGC Corporation), and 10 parts by mass of a (meth)acrylic resin (styrene / stearyl acrylate (80 / 20) (weight average molecular weight (Mw): 10,000)), and the mixture was stirred at 25°C for 60 minutes to obtain actinic ray-curable liquid 1.

[0201] The viscosity of the obtained actinic ray-curable liquid at 25°C before actinic ray irradiation was 300 mPa·s, and the surface tension before actinic ray irradiation was 33 mN / m. The viscosity of the actinic ray-curable liquid was measured using a vibration viscometer "FVM70A-STC" (manufactured by Sekonic Corporation). The vibrator was immersed in the actinic ray-curable liquid in a 25°C environment, and the value after 30 seconds was taken as the viscosity of the actinic ray-curable liquid. The surface tension of the actinic ray-curable liquid was measured using the method described above.

[0202] [Preparation of actinic radiation curable liquids 2 to 7] Actinic ray-curable liquids 2 to 7 were prepared in the same manner as actinic ray-curable liquid 1, except that the (meth)acrylic resin was changed to the (meth)acrylic resin shown in Table 1. The viscosity of actinic ray-curable liquids 2 to 7 before actinic ray irradiation and the surface tension before and after actinic ray irradiation were measured in the same manner as actinic ray-curable liquid 1.

[0203] The components of the actinic ray-curable liquid are shown in Table 1. The content of each component shown in Table 1 is in parts by mass. The abbreviations used in Tables 1 to 3 are as follows: St: styrene STA: stearyl acrylate AA: acrylic acid MA: methyl acrylate BA: n-butyl acrylate MAA: methacrylic acid MMA: methyl methacrylate 2EHA: 2-ethylhexyl acrylate HDDA: 1,6-hexanediol diacrylate TMPTA: Trimethylolpropane triacrylate BP: Benzophenone

[0204] [Table 1]

[0205] 4. Evaluation [Evaluation of physical properties of actinic radiation curing type] The viscosity and cure shrinkage of actinic ray curable liquids 1 to 7 before irradiation with actinic rays, and the surface tension of actinic ray curable liquids 1 to 7 before and after irradiation with actinic rays were measured.

[0206] (viscosity measurement) The viscosity of actinic ray-curable liquids 1 to 7 was measured using a dynamic viscometer "FVM70A-STC" (manufactured by Sekonic Corporation). In an environment of 25°C, an oscillator was immersed in the actinic ray-curable liquid, and the value after 30 seconds was taken as the viscosity of the actinic ray-curable liquid.

[0207] (Measurement of cure shrinkage) Actinic ray-curable liquids 1 to 7 were applied to the surface of a 5 cm x 10 cm PET film (manufactured by Toray Industries, Inc.) using a bar coater #25 to a coating thickness of approximately 50 μm, and the surface coated with the actinic ray-curable liquid was irradiated with actinic rays at 80 mm / s using a 1.5 kW mercury lamp. The distance between the mercury lamp and the applied actinic ray-curable liquid was 5 cm. After actinic ray irradiation, the PET film was placed on a horizontal surface, and the warpage at the four corners of the PET film was measured with a ruler, and the average value was taken as the amount of cure shrinkage.

[0208] (surface tension measurement) The surface tensions of actinic ray-curable liquids 1 to 7 were measured by the pendant drop method using a contact angle meter "DMs-701" (manufactured by Kyowa Interface Science Co., Ltd.) Specifically, actinic ray-curable liquids 1 to 7 were each placed in a syringe needle, and the shapes of the droplets of actinic ray-curable liquids 1 to 7 dropped at 23°C were measured five times for each, and the average values ​​were calculated.

[0209] [Coating and wettability evaluation] The prepared cyan toners 1 to 4 and actinic ray curable liquids 1 to 7 were combined as shown in Table 2, and evaluations of coating properties and adhesion were carried out.

[0210] (Coating property evaluation) The developing machines containing the cyan toners 1 to 4 were placed in a modified image forming device "bizhub PRO C6500" (manufactured by Konica Minolta, Inc.), and an A4-sized recording medium "OK Top Coat, basis weight 157 g / cm 2 A 5 x 5 cm solid image was created using a "Digi UV Coater" (manufactured by Oji Paper Co., Ltd.). Next, actinic radiation curable liquids 1 to 7 were applied to the surface of the image using a varnish coater "Digi UV Coater" (manufactured by BN Technology Co., Ltd.) at a speed of 30 m / min to a coating thickness of 5 μm.

[0211] (Evaluation method) The surface condition where the actinic ray curable liquid was applied was observed with an optical microscope (100x magnification).

[0212] (Evaluation criteria) A: No pinholes are visible within the 1cm x 1cm square. B: There are two or fewer tiny pinholes in a 1cm x 1cm square. C: There are 3 to 5 tiny pinholes in a 1cm x 1cm square. D: There are 6 to 10 tiny pinholes in a 1cm x 1cm square. E: There are 11 or more tiny pinholes in a 1cm x 1cm square, or the product has been repelled.

[0213] (Adhesion evaluation) The developing machines containing cyan toners 1 to 4 were placed in a modified image forming device "bizhub PRO C6500," and an A4-sized recording medium "OK top coat, basis weight 157 g / cm 2 A 5 x 5 cm solid image was created using a "Digi UV Coater" (manufactured by Oji Paper Co., Ltd.). Next, using a varnish coater "Digi UV Coater" (manufactured by BN Technology Co., Ltd.), actinic ray-curable liquids 1 to 7 were applied to the surface of the image at a speed of 30 m / min to a coating thickness of 5 μm. The surface coated with actinic ray-curable liquids 1 to 7 was irradiated with actinic rays to form a cured film on the surface of the image.

[0214] (Evaluation method) 100 squares were cut into the image prepared above, Scotch Ultra Clear Tape S (manufactured by 3M, "Scotch" is a registered trademark of the company) was applied, and the tape was rubbed with a 2 kg roller 10 times, and then slowly peeled off.

[0215] (Evaluation criteria) A: No peeling of the cured film B: There is very slight peeling of the cured film. C: Peeling of the cured film is 30% or less D: Peeling of the cured film is more than 30%.

[0216] Table 2 shows the SP values ​​of the monomers that make up the styrene-acrylic resin and the monomers that make up the actinic radiation curable liquid.

[0217] [Table 2]

[0218] In addition, the minimum SP value among the SP values ​​of the multiple monomers that make up the styrene-acrylic resin is defined as SPa min (J / cm 3 ) 1 / 2 The smallest SP value among the SP values ​​of the monomers that make up the (meth)acrylic resin is defined as SPb min (J / cm 3 ) 1 / 2 The difference between (|SPa min -SPb min |) can be calculated using the values ​​shown in Table 3.

[0219] [Table 3]

[0220] The evaluation results of the coating properties and adhesion are shown in Table 4. In Table 4, CPES represents an aliphatic polyester resin, APES represents an aromatic polyester resin, and the abbreviations in the table are the same as those in Tables 1 to 3.

[0221] [Table 4]

[0222] SPa min and SPb min The difference between (|SPa min -SPb min |) is 0.5 (J / cm 3 ) 1 / 2 It has been found that the applicability of the actinic ray curable liquid can be improved by satisfying the following conditions.

[0223] It was also found that the adhesion could be improved by including styrene as a constituent component in the styrene-acrylic resin contained in the binder resin and the (meth)acrylic resin contained in the actinic radiation curable liquid.

[0224] It was found that the styrene-acrylic resin and the (meth)acrylic resin contained in the actinic radiation-curable liquid can improve the application and adhesion of the actinic radiation-curable liquid by containing 2-ethylhexyl acrylate or 2-ethylhexyl methacrylate as a constituent component. [Industrial Applicability]

[0225] According to the present invention, an image forming method using an actinic radiation-curable liquid that has good coatability and adhesion to a toner image can be provided, and therefore, according to the present invention, it is expected that the performance of electrophotographic image forming apparatuses will be improved and that image forming apparatuses will become more widespread. [Explanation of symbols]

[0226] 1. Image forming device 30 Image processing section 40 Image forming unit 41Y, 41M, 41C, 41K Image forming units 42 Intermediate transfer unit 43 Secondary transfer unit 50 Paper transport section 51 Paper feed section 51a, 51b, 51c Paper feed tray units 52 Paper output section 52a Paper ejection roller 53 Conveying path section 53a Registration roller pair 60 Fixing device 62 Fixing roller 63 Heating Belt 64 Pressure Roller 110 Image reading unit 111 Paper feeder 112 Scanner 112a CCD sensor 411 Exposure equipment 412 Developing device 413 Photosensitive drum 414 Charging device 415 Drum cleaning device 421 Intermediate transfer belt 422 Primary transfer roller 423, 431 Support roller 423A Backup Roller 426 Belt cleaning device 431A Secondary transfer roller 432 Secondary transfer belt D Manuscript S paper

Claims

1. applying an actinic ray curable liquid to the surface of the toner image fixed on the surface of the recording medium; a step of irradiating the actinic ray curable liquid applied to the surface of the toner image with actinic rays to cure the actinic ray curable liquid; and the toner image contains a binder resin, a colorant, and a release agent; the actinic ray-curable liquid contains at least an actinic ray-polymerizable compound and a (meth)acrylic resin; The (meth)acrylic resin is a polymer containing a (meth)acrylic acid ester monomer as a constituent component, the content of the (meth)acrylic resin is 5% by mass or more and 15% by mass or less with respect to the total mass of the actinic ray-curable liquid, the binder resin contains a styrene-acrylic resin, the styrene-acrylic resin contained in the binder resin and the (meth)acrylic resin contained in the actinic ray-curable liquid contain the same monomer as a constituent component; Image forming method.

2. 2. The image forming method according to claim 1, wherein the content of the styrene-acrylic resin is 50% by mass or more based on the total mass of the resin components constituting the binder resin.

3. The smallest SP value among the SP values ​​of the monomers constituting the styrene-acrylic resin is SPa ｍｉｎ (J / cm ３ ) １／２ The smallest SP value among the SP values ​​of the monomers constituting the (meth)acrylic resin is defined as SPb ｍｉｎ (J / cm ３ ) １／２ When The SPa ｍｉｎ and the SPb ｍｉｎ 3. The image forming method according to claim 1, wherein and satisfy the condition of the following mathematical formula (1). [Equation 1]

4. 4. The image forming method according to claim 1, wherein the styrene-acrylic resin contained in the binder resin and the (meth)acrylic resin contained in the actinic ray-curable liquid contain 2-ethylhexyl acrylate or 2-ethylhexyl methacrylate as constituent components.

5. 5. The image forming method according to claim 1, wherein the binder resin contains an aromatic polyester resin.

6. 6. The image forming method according to claim 1, wherein the binder resin contains an aliphatic polyester resin.

7. 7. The image forming method according to claim 1, wherein the actinic ray curable liquid contains a (meth)acrylate.

8. 8. The image forming method according to claim 1, wherein the surface tension of the actinic ray-curable liquid before being irradiated with the actinic ray is 10 mN / m or more and 40 mN / m or less.

9. 9. The image forming method according to claim 1, wherein the surface tension of the coating film formed by curing the actinic ray-curable liquid after irradiation with the actinic ray is 30 mN / m or more.

10. 10. The image forming method according to claim 1, wherein the viscosity of the actinic ray-curable liquid before being irradiated with actinic rays is 200 mPa·s or more and 1000 mPa·s or less at 25°C.

11. 11. The image forming method according to claim 1, wherein the amount of cure shrinkage of the actinic ray curable liquid irradiated with the actinic ray is 20 mm or less.

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