JP2013092671A - Toner, manufacturing method of toner, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner that prevents fusion of toner particles during storage or in a developing unit and has high durability and high glossiness, a manufacturing method of toner, and an image forming method.SOLUTION: A toner has a core-shell structure containing at least resin, and a part of the resin contained in a core layer contains a UV-curing resin.

Description

  The present invention relates to a toner, a toner manufacturing method, and an image forming method.

In the printing field, an electrophotographic image forming method is widely used. The characteristics required for electrophotographic toners used in the printing field include low-temperature fixing of toner that can be fixed with low thermal energy that can be used for high-speed processes, and micro-size that can support high image quality comparable to offset printing. The main thing is to reduce the particle size of the toner that can faithfully reproduce a simple dot image. In recent years, in addition to that, electrophotographic printing has been expanded to print on other than paper media, and a toner suitable for such use is demanded.
In particular, toners used for outdoor display, floor display, and the like require durability such as wear resistance, chemical resistance, water resistance, and oil resistance. As a toner having improved durability, for example, a toner containing a polymer formed from styrene and acrylate, an ultraviolet curable acrylate oligomer, and a colorant as necessary is disclosed (for example, see Patent Document 1). ). According to this toner, an overcoat applied after the toner is not required on the toner, and the toner has excellent friction resistance and solvent resistance.

JP 2005-182041 A

However, since the toner disclosed in Patent Document 1 contains a lower molecular weight oligomer (ultraviolet curable acrylate oligomer) together with a polymer as a toner constituent component, the toner particles are melted by storing the toner at a high temperature. There is a problem that toner particles are fused to the carrier due to adhesion or friction with the carrier in the developing device.
On the other hand, in order to obtain a highly glossy image, techniques such as lowering the molecular weight and glass transition point of the binder resin in the toner component are known. However, when the molecular weight and glass transition point of the binder resin are lowered, the resin design is contrary to the durability of the image, and it has been difficult to achieve both high durability and high gloss. Further, a high gloss technology for covering an image with a transparent and highly smooth resin in a subsequent process is also known, but there is a problem that it takes time for the processing.
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and there is no problem of toner particle fusion during storage or in a developing device, and the production of toner and toner that can achieve both high durability and high glossiness. It is an object to provide a method and an image forming method.

According to the invention of claim 1, in the toner having a core-shell structure containing at least a resin,
A toner is provided in which a part of the resin contained in the core layer contains an ultraviolet curable resin.

  According to the invention of claim 2, the toner according to claim 1, wherein the ultraviolet curable resin is an ultraviolet curable resin having in its molecule a photoinitiating functional group that generates radicals by ultraviolet rays. Is provided.

  According to the invention of claim 3, the glass transition point of the ultraviolet curable resin contained in the core layer is lower than the glass transition point of the resin contained in the shell layer, and is contained in the core layer. 3. The toner according to claim 1, wherein a difference between a glass transition point of the ultraviolet curable resin and a glass transition point of the resin contained in the shell layer is 25 to 50 ° C. 3.

According to invention of Claim 4, the said ultraviolet curable resin is an ultraviolet curable resin obtained by carrying out the addition reaction of the monomer of following (5) to the monomer of following (1)-(4). A toner according to any one of claims 1 to 3 is provided.
(1) Carboxyl group-containing vinyl polymerization monomer (2) Photoinitiating functional group-containing vinyl polymerization monomer (3) Isocyanate group, hydroxyl group or glycidyl group-containing vinyl polymerization monomer (4) Co-polymerized with the monomers (1) to (3) above Other vinyl polymerizable monomers capable of polymerization (5) Vinyl polymerizable monomers containing a reactive functional group capable of reacting with the monomer (3)

According to the invention of claim 5, in the method for producing a toner having a core-shell structure containing at least a resin,
Mixing a dispersion of resin particles containing at least an ultraviolet curable resin and a dispersion of colorant particles, and aggregating the resin particles and the colorant particles to form a core layer;
Coating the core layer with a resin to form a shell layer;
A method for producing a toner is provided.

According to the invention of claim 6, at least a charging step for charging the photoreceptor,
An exposure step of forming an electrostatic latent image on the photoreceptor;
A developing step of developing the electrostatic latent image with toner;
A transfer step of transferring the toner image on the photoreceptor to a transfer material;
A fixing step of fixing the toner image to the transfer material;
A UV irradiation step of irradiating the toner image after fixing with UV,
The toner has a core-shell structure containing at least a resin;
An image forming method is provided in which a part of the resin contained in the core layer contains an ultraviolet curable resin.

  According to the present invention, there is no problem of toner particle fusion during storage or in the developing device, and both high durability and high gloss can be achieved.

1 is a diagram illustrating an internal configuration of a digital image forming apparatus that can be used in the present invention.

Hereinafter, the present invention will be specifically described.
〔toner〕
The electrostatic image developing toner of the present invention has a core-shell structure containing at least a resin, and a part of the resin contained in the core layer contains an ultraviolet curable resin.
An uncured ultraviolet curable resin is a resin close to a polymer precursor having a low molecular weight and a low glass transition point, and has a soft property. Therefore, the uncured ultraviolet curable resin spreads smoothly and smoothly at the time of fixing, and becomes a high gloss image at the time of photocuring.
In addition, in order to prevent fusion of toner particles from the production of the toner to the storage of the toner to the development to the transfer, the toner has a core-shell structure containing an ultraviolet curable resin in the core layer, and the periphery thereof is made of glass. Cover with a shell resin with a high transition point. By using such a toner, the hard shell layer prevents fusion of toner particles from the production of the toner to the storage of the toner to the development to the transfer. At the time of fixing, the uncured ultraviolet curable resin of the core layer that has leached out functions to adhere to the transfer body, and at the same time, it is photocured by ultraviolet irradiation to form a firm image.
As a result, a highly durable and highly glossy toner image can be formed.

《Photoinitiator》
Photocuring requires a photoinitiator that generates radicals by ultraviolet rays.
As the photoinitiator, acetophenone, benzophenone, other aromatic ketones and the like are generally known, but in the presence of various components such as an ultraviolet curable resin, another binder resin, a colorant, and a release agent, It is difficult to include a necessary amount of such a photoinitiator in the vicinity of the ultraviolet curable resin in a toner prepared by an aggregation association method of latex (resin particle dispersion), and the toner design is greatly restricted.
Therefore, in the present invention, it is preferable to use, as the ultraviolet curable resin of the toner, an ultraviolet curable resin having in its molecule a photoinitiating functional group that generates radicals by ultraviolet rays.

<< UV curable resin having photoinitiating functional group in molecule >>
The ultraviolet curable resin (hereinafter referred to as polymer compound (A)) having a photoinitiating functional group that generates radicals by ultraviolet rays in the molecule is the following (1) to (4) monomers, It can be obtained by addition reaction of monomers.
(1) Carboxyl group-containing vinyl polymerization monomer (2) Photoinitiating functional group-containing vinyl polymerization monomer (3) Isocyanate group, hydroxyl group or glycidyl group-containing vinyl polymerization monomer (4) Co-polymerized with the monomers (1) to (3) above Other vinyl polymerizable monomers capable of polymerization (5) Vinyl polymerizable monomers containing a reactive functional group capable of reacting with the monomer (3)

(1) Carboxyl group-containing vinyl polymerization monomer Examples of the carboxyl group-containing vinyl polymerization monomer include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid. The carboxyl group functions to stabilize the emulsification dispersion of the resin in the aqueous phase during the resin particle dispersion (latex).
The use range of the carboxyl group-containing vinyl polymerization monomer is preferably 0.1 to 20% by mass, particularly preferably 1 to 10% by mass, based on the total amount of the polymer compound (A).

(2) Photoinitiating functional group-containing vinyl polymerization monomer Photoinitiating functional group-containing vinyl polymerization monomers include 4-acryloyloxyethyloxy-4-chlorobenzophenone, 4-methacryloyloxypropyloxy-4-chlorobenzophenone, 4- Acryloyloxybutyloxy-4-chlorobenzophenone, benzoincarbonylmethyl methacrylate, (2-benzoyl-4-methoxy) phenoxycarbonylmethyl methacrylate, p-nitroanilinocarboxymethyl methacrylate, 4-nitro-1-naphthylaminocarboxymethyl methacrylate Rate and the like.
The use range of the photoinitiating functional group-containing vinyl polymerization monomer is preferably 0.1 to 20% by mass, particularly preferably 1 to 10% by mass, based on the total amount of the polymer compound (A). preferable.

(3) Isocyanate group, hydroxyl group or glycidyl group-containing vinyl polymerization monomer As the isocyanate group, hydroxyl group or glycidyl group-containing vinyl polymerization monomer, 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 1,1-bis (acryloyloxy) Methyl) ethyl isocyanate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, glycidyl acrylate and the like.
The range of use of these isocyanate group, hydroxyl group or glycidyl group-containing vinyl polymerization monomers is preferably 1 to 70% by mass, particularly preferably 10 to 30% by mass, based on the total amount of the polymer compound (A). Is preferred.

(4) Other vinyl polymerization monomers copolymerizable with the monomers (1) to (3) The other vinyl polymerization monomers copolymerizable with the monomers (1) to (3) are not particularly limited. However, for example, (meth) acrylic acid ester, styrene, α-methylstyrene (meth) acrylonitrile, vinyl acetate, (meth) acrylamide and the like can be mentioned. Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-methoxyethyl (meth). Examples include acrylate and isoboronyl (meth) acrylate.
The use range of the other vinyl polymerization monomer copolymerizable with the monomers (1) to (3) can be in the range of 1 to 99% by mass with respect to the total amount of the polymer compound (A).

(5) Vinyl polymerization monomer containing a reactive functional group capable of reacting with the monomer of (3) As a vinyl polymerization monomer containing a reactive functional group capable of reacting with the monomer of (3), a hydroxyl group-containing unsaturated monomer, An isocyanate group-containing unsaturated monomer, a glycidyl group-containing unsaturated monomer, and the like are used, and among these, those that undergo an addition reaction with the vinyl polymerization monomer (3) are used in combination.
The use range of the vinyl polymerization monomer containing a reactive functional group capable of reacting with the monomer of (3) is 0.5 to 1 equivalent with respect to the isocyanate polymerization group, hydroxyl group or glycidyl group-containing vinyl polymerization monomer. More preferably, the amount is such that the vinyl polymerization monomer containing a reactive functional group capable of reacting with the monomer (3) does not remain after the addition reaction.

For example, the polymer compound (A) blocks the active energy rays such as ultraviolet rays and electron beams, and in the presence of a polymerization initiator in a solvent, the monomers (1), (2), (3), (4) Can be obtained by addition reaction of (5).
As the solvent used for the polymerization, a solvent that does not contain a functional group involved in the addition reaction and is water-soluble is preferable. Examples include dipropylene glycol dimethyl ether, 1,4-dioxane, tetrahydrofuran and the like. These solvents can be used alone or in combination of two or more.
The polymerization initiator used for the polymerization is not particularly limited as long as it is usually used, and examples thereof include azobisisobutyronitrile, azobis (2-methylbutyronitrile), and benzoyl peroxide. Examples of the addition reaction catalyst include di-n-butyltin dilaurate. The polymerization temperature of the polymer compound (A) is usually 30 to 150 ° C, preferably 80 to 120 ° C.
The weight average molecular weight (Mw) of the polymer compound (A) is preferably from 1,000 to 100,000, particularly preferably from 1,000 to 10,000. Further, the glass transition point has a low glass transition point around room temperature, preferably from -10 ° C to 40 ° C, particularly preferably from 10 ° C to 25 ° C.
The polymer compound (A) can be made into a resin particle dispersion (latex) by adding water and a base after the addition reaction and performing phase inversion emulsification with stirring.
Examples of the base used for neutralizing the carboxyl group include sodium hydroxide, potassium hydroxide, ammonia, triethanolamine, triethylamine, trimethylamine, diethanolamine and the like. As a use range of a base, 0.5-1.5 equivalent is desirable with respect to a carboxyl group. If it is 0.5 equivalent or less, the dispersion stability in water is lowered, and if it is 1.5 equivalent or less, the surface strength as a toner image after curing is lowered.
Further, a known emulsifier can be added during phase inversion emulsification. For example, alkyl sulfates, alkylbenzene sulfonates, alkyl sulfosuccinates, alkyl ether sulfates, polyoxyethylene alkyl ethers, polyoxyalkylphenyl ethers and the like can be mentioned. The concentration of the resin particle dispersion (latex) is not particularly limited as long as the latex is in a stable range. For example, the solid content is preferably 5 to 70% by mass, particularly preferably 10 to 40% by mass. Is preferred.

<Core shell toner>
The toner of the present invention is characterized in that a core-shell structure is formed, an ultraviolet curable resin is contained in the core layer, and the periphery thereof is coated with a shell resin having a high glass transition point. Specifically, the glass transition point of the ultraviolet curable resin contained in the core layer is preferably lower than the glass transition point of the shell resin, and the difference is preferably 25 to 50 ° C.
If the temperature is less than 25 ° C., the strength of the shell layer relative to the core layer is not sufficient, so that the toner particles are fused. If the temperature exceeds 50 ° C., the glass transition point of the shell resin is high, the seepage of the uncured ultraviolet curable resin is inhibited during fixing, the fixing property is lowered, and image defects such as low-temperature offset occur.

  The content of the ultraviolet curable resin in the core layer is preferably 5% by mass to 40% by mass, and more preferably 15% by mass to 30% by mass with respect to the total amount of the toner resin. Further, the content of the shell resin is preferably 1% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass with respect to the total amount of the toner resin.

In the toner of the present invention, examples of other binder resins used together with the ultraviolet curable resin include polycondensation resins such as polyester, polyamide, and polyurethane, polystyrene, polyethylene, (meth) acrylic acid ester, vinyl chloride, vinyl acetate, and the like. Examples of the vinyl polymerization resin include a vinyl polymerization resin, and in particular, in view of the toner production method based on the aggregation association method of the resin particle dispersion (latex), the vinyl polymerization resin from which the resin particle dispersion (latex) can be directly obtained by emulsion polymerization. Is preferred.
Another binder resin may be used for forming the core layer together with the ultraviolet curable resin, or may be used as a shell resin for forming the shell layer.

The molecular weight of the other binder resin used for the core layer is preferably 1,000 to 100,000, and particularly preferably 10,000 to 50,000. The glass transition point is preferably 20 ° C to 60 ° C, and particularly preferably 30 ° C to 50 ° C.
Since the other binder resin used for the shell layer has a function of preventing fusion of toner particles, the molecular weight is preferably 10,000 to 200,000, and particularly preferably 20,000 to 10,000. The glass transition point is preferably 30 ° C to 80 ° C, particularly preferably 40 ° C to 70 ° C.

Moreover, you may make a core layer contain a mold release agent.
Examples of the release agent include the following.
(1) Long-chain hydrocarbon wax Polyolefin wax such as polyethylene wax and polypropylene wax, paraffin wax, sazol wax, etc. (2) Ester wax Trimethylolpropane tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrasteare Rate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitic acid, distearyl maleate, etc. (3) Amide wax Ethylenediamine dibehenyl amide, trimellitic acid tristearyl amide, etc. (4) Dialkyl ketone waxes, distearyl ketone, etc. (5) Others Carnaubawack , Montan waxes, and the like.
The content of the release agent in the toner is preferably 1% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass.

The toner of the present invention may contain a colorant. Examples of the colorant that can be used include the following.
Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.
Examples of the colorant for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48; 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.
Examples of the colorant for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.
Further, as a colorant for green or cyan, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15; 2, C.I. I. Pigment blue 15; 3, C.I. I. Pigment blue 15; 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. And CI Pigment Green 7.
These colorants can be used alone or in combination of two or more as required. Further, the amount of the colorant added is in the range of 1 to 30% by mass, preferably 2 to 20% by mass, based on the whole toner, and a mixture thereof can also be used. The number average primary particle diameter varies depending on the type, but is preferably about 10 to 200 nm.

[Toner Production Method]
The toner of the present invention is produced by an aggregation and association method of a resin particle dispersion (latex).
A latex containing an ultraviolet curable resin, a latex containing another binder resin, and a dispersion of colorant particles are used to agglomerate to the desired toner particle size, and at the same time, heated above the glass transition temperature. Together, toner core particles (core layer) are formed (aggregation step). In this aggregating step, internal additive particles such as release agent particles and charge control agents can be agglomerated together with the dispersion of latex and colorant particles.
Thereafter, a shell resin is coated on the outer peripheral surface of the toner core particles produced in the aggregation process so as to have a core-shell structure, thereby forming a shell layer (shell formation process).
Further, the liquid containing the particles forming the shell layer is then heated and stirred to adjust the heating temperature, stirring speed, and heating time until a desired circularity is obtained, thereby obtaining a dispersion of toner base particles.
Thereafter, the toner base particles are filtered off from the aqueous medium, and a filtration and washing step for removing the surfactant and the like from the toner base particles is performed.
Further, the toner base particles that have been subjected to the cleaning treatment are dried, and a drying process is performed to obtain dried toner base particles.
In addition, as a post-treatment step, an external additive such as a so-called post-treatment agent, a fluidizing agent or a cleaning aid, may be added to the toner particles in order to improve fluidity, chargeability, cleaning properties, and the like. good. Commonly used general additives can be used as the external additive, and silica particles and titania particles are particularly preferable.

(Developer)
The toner produced by the above-described production method can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer.
In the case where the toner produced by the above-described manufacturing method is used as a two-component developer, the carrier has conventionally been a metal such as iron, ferrite or magnetite, or an alloy of such a metal with a metal such as aluminum or lead. Magnetic particles made of known materials can be used, and ferrite particles are particularly preferable.
Further, as the carrier, a coat carrier in which the surface of the magnetic particles is coated with a coating agent such as a resin, a binder type carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.

The coating resin constituting the coat carrier is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, silicone resins, ester resins, and fluorine resins.
Moreover, it does not specifically limit as resin which comprises a resin dispersion type carrier, A well-known thing can be used, For example, a styrene-acrylic-type resin, a polyester resin, a fluororesin, a phenol resin etc. can be used.
The volume-based median diameter of the carrier is preferably 20 to 100 μm, and more preferably 20 to 60 μm.
The volume-based median diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

(Image forming method)
The image forming method of the present invention can be suitably used for an image forming method including a UV irradiation step of irradiating UV (ultraviolet rays) after a fixing step by a heat and pressure fixing method capable of applying pressure and heating.
Specifically, in this image forming method, the toner as described above is used, for example, the photoreceptor is uniformly charged (charging process), and an electrostatic latent image is formed on the photoreceptor (exposure process). ), Developing the electrostatic latent image formed on the photoconductor to obtain a toner image (development process), transferring the toner image to a transfer body (transfer process), and then transferring the toner onto the transfer body The image is fixed on the transfer member by a fixing process using a thermal pressure fixing method (fixing step), and then the fixed toner image is irradiated with UV (UV irradiation step) to obtain a printed matter on which a visible image is formed. .

[Image forming apparatus]
An example of the image forming apparatus used in the image forming method of the present invention is a digital image forming apparatus shown in FIG. FIG. 1 is a diagram illustrating an internal configuration of a digital image forming apparatus.
The image forming apparatus 1 has a plurality of transfer material storage units 20 at the bottom. An image forming unit 40 and an intermediate transfer belt 50 are installed above the transfer material storage unit 20, and a document reading unit 30 is installed at the upper part of the apparatus main body.
The transfer material storage unit 20 can be pulled out to the front side of the apparatus (the front side in FIG. 1).
The image forming unit 40 includes four sets of image forming units 400Y, 400M, 400C, and 400K for forming toner images for each color of Y, M, C, and K. The image forming units 400Y, 400M, and 400K 400C and 400K are linearly arranged from top to bottom in this order, and each has the same configuration. The configuration of the image forming unit 400Y will be described as an example. The image forming unit 400Y includes a photoreceptor 410 that rotates counterclockwise, a scorotron charging unit 420, an exposure unit 430, and a developing unit 440.
The cleaning unit 450 is disposed to include a region facing the lowermost part of the photoconductor 410.

The intermediate transfer belt 50 located at the center of the apparatus main body is endless and has an appropriate volume resistivity. Further, the intermediate transfer belt 50 is formed on the outside of a semiconductive film substrate in which a conductive material is dispersed in an engineering plastic such as knitted polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, and nylon alloy. It consists of two layers with fluorine coating. Further, there may be a conductive material dispersed in silicon rubber or urethane rubber.
The primary transfer electrode 510 is installed at a position facing the photoconductor 410 with the intermediate transfer belt 50 interposed therebetween.

A process for forming a color image using such an image forming apparatus 1 will be described.
The photoconductor 410 is driven by a main motor (not shown), the surface of the photoconductor 410 is supplied with a voltage by a power source (not shown), and is charged positively by the discharge of the scorotron charging means 420 (in this embodiment). + 800V). Next, optical writing according to image information is performed by the exposure unit 430, and an electrostatic latent image is formed on the photoreceptor 410. When the formed electrostatic latent image passes through the developing unit 440, the toner charged positively in the developing unit 440 adheres to the portion of the latent image by application of the positive developing bias, and the toner is deposited on the photoreceptor 410. An image is formed. The formed toner image is transferred to the intermediate transfer belt 50 that is pressure-bonded to the photoreceptor 410. The toner on the photoreceptor 410 remaining after the transfer is cleaned by the cleaning means 450. A toner image formed by each of the image forming units 400Y, 400M, 400C, and 400K is transferred to the intermediate transfer belt 50 so that a color image is formed on the intermediate transfer belt 50. The transfer material P is discharged one by one by the transfer material storage unit 20 and conveyed to the position of the registration roller 60. After the leading ends of the transfer material P are aligned by the registration roller 60, the transfer material P is fed from the registration roller 60 at a timing when the toner image on the intermediate transfer belt 50 and the image position coincide with each other. The transfer material P fed by the registration roller 60 is guided by a guide plate and fed to a transfer nip portion formed by the intermediate transfer belt 50 and the transfer portion 70. The transfer unit 70 constituted by rollers presses the transfer material P toward the intermediate transfer belt 50 side. By applying a bias (−500 V) having a polarity opposite to that of the toner to the transfer unit 70, the toner image on the intermediate transfer belt 50 is transferred to the transfer material P by the action of electrostatic force. The transfer material P is neutralized by a separating means (not shown) including a static elimination needle, separated from the intermediate transfer belt 50, and sent to the fixing device 80 and the UV irradiation device 103. As a result, the toner image is fixed on the transfer material P, and after UV irradiation, the transfer material P on which the toner image is formed is discharged out of the image forming apparatus.
The fixing device 80 and the UV irradiation device 103 that can be suitably used in the image forming method of the present invention will be described below.

<Fixing device>
As a suitable fixing method using the toner of the present invention, a so-called contact heating method is preferable. As the contact heating method, a thermal pressure fixing method is particularly preferable. Specifically, as will be described later with reference to FIG. 1, a fixing belt that is heated and rotated by a heating roller, a fixing roller that supports the fixing belt, and a pressure member that faces the fixing roller via the fixing belt are provided. A nip portion is formed between the fixing belt and the pressure member, and the transfer material is passed through the nip portion to fix the toner on the transfer material. That is, it is preferable that the heat supplied to the toner is supplied not from the inside of the fixing roller forming the nip portion but from the heating roller provided separately to the nip portion via the belt.
As another thermal pressure fixing method, a roller pair including a heating roller and a pressure roller in contact with the heating roller is provided, and the pressure roller is deformed by the pressure applied between the heating roller and the pressure roller. You may use the fixing device by which what is called a nip part is formed in a deformation | transformation part.

  As shown in FIG. 1, the fixing device 80 passes the transfer material through a nip region formed by the pressure member 801 and the fixing belt 803 to fix the toner image on the transfer material.

  The pressurizing member 801 covers, for example, a silicon rubber (thickness 2 mm, hardness 10 ° (measured with a JIS K6253 type A durometer (A type))) on the outer periphery of a hollow aluminum core (thickness 2 mm). A φ50 mm roller having PFA (perfluoroalkoxy) coated thereon (30 μm). What coated PTFE (polytetrafluoroethylene) instead of PFA may be used. Further, in order to prevent a rapid temperature drop of the pressure member 801, the pressure member 801 having a halogen heater inside may be used.

  The fixing belt 803 is stretched by a fixing roller 804 and a heating roller 806, and rotates in the direction of the arrow shown in FIG. The fixing belt 803 is a three-layered belt made of, for example, polyimide (110 μm), silicon rubber (200 μm), and PTFE coating (30 μm).

  The fixing roller 804 that presses the fixing belt 803 in the direction of the pressure member 801 is, for example, a φ40 mm roller in which a solid SUS core metal is coated with silicon rubber (7 mm) and coated with PFA or the like. .

  The heating roller 806 is, for example, a hollow aluminum core (thickness 2 mm) coated with PFA (30 μm) and has a halogen heater 805 inside.

  Reference numerals 807, 808, and 809 denote non-contact type temperature sensors. The temperature sensor 807 detects the temperature of the pressure member 801, the temperature sensor 808 detects the temperature of the heating roller 806, and the temperature sensor 809 detects the temperature of the nip portion 810. ing.

<UV irradiation device>
For example, as shown in FIG. 1, the UV irradiation device 103 is preferably composed of a light source lamp 104, a reflection plate 105, and a cooling device (not shown).
The light source lamp 104 may be anything that emits general ultraviolet rays, and may include wavelengths in the visible light and infrared region, low pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, metal halide lamp, high power. A metal halide lamp, a xenon lamp, an excimer lamp, an ultraviolet light emitting LED, or the like can be used, and is appropriately selected depending on the wavelength and illuminance. In the image forming method of the present invention, an LED that is easy to handle can be used.

  The reflection plate 105 for efficiently irradiating the unfixed toner image with UV may be a condensing type or a parallel light type, and is preferably one that diffuses uniformly over a wide range with respect to the unfixed toner image. A type that reflects UV efficiently and allows visible light and infrared rays to be transmitted behind the reflector is also possible.

The cooling device cools the lamp and the reflector, and there are an air cooling type using an air flow, a water cooling type cooling with water, and an air cooling / water cooling type cooling the lamp with an air flow and cooling the reflection plate with water. There are, but either scheme can be used.
Specifically, the wavelength of the irradiated UV may be long-wavelength ultraviolet light centering around 365 nm, and those containing short-wavelength ultraviolet light and medium-wavelength ultraviolet light can also be used.
The output is generally UV irradiance in step 10~100mW / cm ^2, light amount if 50 to 500 mJ / cm ^2, worthy of use.

  As described above, in the fixing device 80, the transfer material P is passed through the nip portion 810 formed by the pressure member 801 and the fixing belt 803, and the toner image is fixed on the transfer material P. Then, the fixed toner image is irradiated with UV.

[Transfer]
Examples of the transfer body used in the image forming method of the present invention include plain paper from thin paper to thick paper, high-quality paper, coated printing paper such as art paper or coated paper, commercially available Japanese paper or postcard paper, OHP Various types of plastic film, cloth, etc. can be mentioned, but are not limited thereto.

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.
[Production of UV-curable latex containing UV-curable resin]
In a light-shielding reaction vessel equipped with a thermometer, a stirring bar, a reflux condenser, and a dropping funnel, 60 parts by mass of dipropylene glycol dimethyl ether is stirred and heated to 110 ° C., and 1 monomer mixture M-1 shown below is added. Added dropwise over 5 hours. One hour after the completion of dropping, 1 part by mass of azobisisobutyronitrile and 3 parts by mass of dipropylene glycol dimethyl ether were added, and the mixture was further stirred at 110 ° C. for 2 hours. After cooling the temperature to 60 ° C., the following addition mixture A-1 was added.
30 minutes after addition of addition mixture A-1, 0.1 part by mass of di-n-butyltin dilaurate was added, and the mixture was further stirred at 60 ° C. for 4 hours. After adding 1.1 equivalents of sodium hydroxide (with respect to methacrylic acid) under high stirring and stirring for 30 minutes, 1100 parts by mass of water was added dropwise over 30 minutes, cooled to room temperature, and UV curable with a solid content of 22% by mass. A resin-containing latex UVL-1 was obtained. The molecular weight and glass transition point of the UVL-1 UV-curable resin-containing latex UVL-1 measured by drying were Mw 4,000 and Tg was 19 ° C., respectively.

(Monomer mixture M-1)
Methyl methacrylate 55 parts by mass 2-ethylhexyl acrylate 90 parts by mass 2-hydroxyethyl methacrylate 75 parts by mass Methacrylic acid 20 parts by mass
4-acryloyloxyethyloxy-4-chlorobenzophenone 20 parts by mass Dipropylene glycol dimethyl ether 20 parts by mass Azobisisobutyronitrile 1.5 parts by mass Octylthioglycol 7.5 parts by mass

(Addition mixture A-1)
2-Methacryloyloxyethyl isocyanate 65 parts by mass Dipropylene glycol dimethyl ether 10 parts by mass Hydroquinone 0.5 parts by mass

[Manufacture of core resin-containing latex CL-1]
In the present invention, the core resin particles were prepared by two-stage polymerization.
<First stage polymerization>
A reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device was charged with a solution prepared by dissolving 7 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate in 1000 parts by mass of ion-exchanged water, and brought to 80 ° C. After heating, a solution obtained by dissolving the following first-stage polymerization monomer mixture at 75 ° C. was added, and using a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path, A dispersion liquid containing emulsified particles (oil droplets) was prepared by mixing and dispersing for 1 hour. Next, a polymerization initiator solution in which 6 parts by mass of potassium persulfate was dissolved in 120 parts by mass of ion-exchanged water was added to this dispersion, and polymerization was performed by heating and stirring the system at 82 ° C. for 1 hour. It was.

(First-stage polymerization monomer mixture)
Styrene 150 parts by mass n-butyl acrylate 70 parts by mass Itaconic acid 7 parts by mass n-octyl mercaptan 2.8 parts by mass WAX-A (pentaerythritol behenate) 120 parts by mass

《Second stage polymerization》
Furthermore, a solution prepared by dissolving 8 parts by mass of potassium persulfate in 160 parts by mass of ion-exchanged water was added, and the following second-stage polymerization monomer mixture was added dropwise over 1 hour under a temperature condition of 82 ° C. After completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, followed by cooling to 40 ° C. to obtain a resin particle liquid. This is designated as core resin-containing latex CL-1. The molecular weight and glass transition point measured by drying the core resin-containing latex CL-1 were Mw 31,000 and Tg was 37 ° C., respectively.

(Second stage polymerization monomer mixture)
Styrene 260 parts by mass n-butyl acrylate 105 parts by mass Itaconic acid 12 parts by mass n-octyl mercaptan 5 parts by mass

[Production of shell resin-containing latex SL-1]
While adding 2.3 parts by mass of sodium dodecyl sulfate to 3000 parts by mass of ion-exchanged water in a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device, stirring at a stirring speed of 230 rpm under a nitrogen stream, The internal temperature was raised to 80 ° C. After raising the temperature, 10 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water is added, and the following monomer mixture is added dropwise over 1 hour, followed by heating and stirring at 80 ° C. for 2 hours. Polymerization was performed to prepare resin particles. This is designated as shell resin-containing latex SL-1. The molecular weight and glass transition point measured by drying SL-1 were Mw 53,000 and Tg was 54 ° C., respectively.

(Monomer mixture)
Styrene 520 parts by weight n-butyl acrylate 210 parts by weight Methacrylic acid 70 parts by weight n-octyl mercaptan 3 parts by weight

(Production of colorant dispersion)
90 g of sodium dodecyl sulfate was dissolved in 1600 ml of ion-exchanged water with stirring. While stirring this solution, 420 g of carbon black (Regal 330R: manufactured by Cabot Corporation) was gradually added, and then dispersed using a stirring device “CLEARMIX” (manufactured by M Technique Co., Ltd.) A dispersion of colorant particles was prepared. The particle diameter of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.) and found to be 110 nm.

[Production of Toner 1]
《Agglomeration / fusion process》
In a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction device, 260 parts by mass of core resin-containing latex CL-1 and 100% by mass of UV-curable resin-containing latex UVL- are converted to solids. Part, 1000 parts by mass of ion-exchanged water, and 32 parts by mass of the dispersion of the colorant particles in terms of solid content were adjusted to 30 ° C., and then the pH was adjusted to 10 by adding a 5N aqueous sodium hydroxide solution. It was adjusted.
Next, an aqueous solution in which 60 parts by mass of magnesium chloride was dissolved in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring at a stirring speed of 230 rpm. After holding for 3 minutes, the solution was heated to 90 ° C. over 60 minutes. After completion of the temperature increase, the stirring speed was lowered to 170 rpm and maintained at 90 ° C., and a core resin growth reaction was performed. When the volume-based median diameter (D ₅₀ ) reaches 6.0 μm, the stirring speed is increased to 280 rpm, and the shell resin-containing latex SL-1 is added over 40 parts by mass in terms of solid content over 10 minutes. Shelling reaction was performed by attaching shell resin around the resin. 120 minutes after the addition of the shell resin-containing latex SL-1, an aqueous solution in which 80 parts by mass of sodium chloride was dissolved in 400 parts by mass of ion-exchanged water was added to stop the shelling reaction. Further, the particles were heated and stirred at a liquid temperature of 92 ° C. as a fusing step, and the fusing between the particles was advanced until the circularity became 0.945 as measured by “FPIA-2100”.
Thereafter, the solution was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped to obtain a dispersion of particles having a core-shell structure. The obtained dispersion is referred to as “dispersion of toner base particles 1”.

《Cleaning / drying process》
The “dispersion of toner base particles 1” produced in the aggregation / fusion process is solid-liquid separated with a basket type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.), and toner base particles 1 A wet cake was formed. The wet cake is washed with ion exchange water at 40 ° C. until the electrical conductivity of the filtrate reaches 5 μS / cm with the basket-type centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). The toner was dried until the amount became 1.0% by mass or less to produce “toner base particles 1”.

<External processing>
1% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 0.3% by mass of hydrophobic titania (number average primary particle size = 20 nm) are added to the “toner base particle 1” obtained above. Then, “Toner 1” was produced by mixing with a Henschel mixer.

[Production of Toner 2]
In the toner 1 production, the core resin-containing latex CL-1 was changed to 360 parts by mass in terms of solid content, and the UV-curable resin-containing latex UVL-1 was excluded. Similarly, “Toner 2” was produced.

[Production of Toner 3]
The same procedure as in the production of Toner 1 except that the core resin-containing latex CL-1 was changed to 300 parts by mass in terms of solid content and the shell resin-containing latex SL-1 was excluded in the aggregation / fusion process of the toner 1 production. Thus, “Toner 3” was produced.

[Manufacture of UVL-2 UV-curable resin-containing latex]
In a four-necked flask equipped with a nitrogen gas introduction tube, a thermometer, a reflux condenser and a stirring device, 365.7 parts by mass of propylene glycol monomethyl ether was charged, and the temperature of the reaction system was raised to 120 ° C. A monomer mixture (160 parts by weight of methacrylic acid, 200 parts by weight of acrylic acid ethyl ester, 250 parts by weight of acrylic acid n-butyl ester, and 40 parts by weight of di-t-butyl peroxide) is dropped into the reaction system over 5 hours. Thus, a polymerization reaction was performed. Next, the reaction system was kept at the same temperature for 2 hours, and then the propylene glycol monomethyl ether was removed under reduced pressure at 160 ° C. and cooled to 80 ° C. Next, an aqueous solution of an acrylic copolymer salt was obtained by adding 120 parts by mass of 25% ammonia water and 1080 parts by mass of soft water to the reaction system.
Next, to 55 parts by mass of the aqueous solution of the acrylic copolymer salt, 40 parts by mass of pentaerythritol tri (meth) acrylate and 40 parts by mass of trimethylolpropane triacrylate were added and stirred sufficiently, and then 140 parts by mass of water was gradually added. While adding, the mixture was vigorously stirred at 40 ° C. for 1 hour. Next, 5 parts by mass of a photopolymerization initiator (trade name “Irgacure 2959”, manufactured by Ciba Specialty Chemicals Co., Ltd.) was added and stirred well, and UVL-2 containing a UV curable resin containing a solid content of 35% by mass was added. Obtained. The molecular weight and glass transition point of the UVL-2 UV-curable resin-containing latex UVL-2 measured by drying were Mw 10,000 and Tg 21 ° C., respectively.

[Production of Toner 4]
In the aggregation / fusion process of toner 1 production, the UV curable resin-containing latex UVL-1 is changed to UVL-2 to give 60 parts by mass in terms of solid content, and the core resin-containing latex CL-1 is 300 in terms of solid content. “Toner 4” was produced in the same manner as in the production of Toner 1 except that the amount was in parts by mass.

[Manufacture of UVL-3 UV-curable resin-containing latex]
An ultraviolet curable resin-containing latex UVL-3 was produced in the same manner as the ultraviolet curable resin-containing latex UVL-1, except that the monomer mixture and the addition mixture were changed as follows.
(Monomer mixture M-2)
Methyl methacrylate 40 parts by mass 2-ethylhexyl acrylate 100 parts by mass 2-hydroxyethyl acrylate 75 parts by mass Methacrylic acid 15 parts by mass
4-Acryloyloxyethyloxy-4-chlorobenzophenone 20 parts by mass Dipropylene glycol dimethyl ether 20 parts by mass Azobisisobutyronitrile 1.5 parts by mass Octylthioglycol 6.5 parts by mass (addition mixture A-2)
2-Acryloyloxyethyl isocyanate 65 parts by weight Dipropylene glycol dimethyl ether 10 parts by weight Hydroquinone 0.5 parts by weight The molecular weight and glass transition point of the UVL-3 UV-curable resin-containing latex measured by drying are Mw 7,000 and Tg, respectively. Was 13 ° C.

[Production of Shell Resin-Containing Latex SL-2]
While adding 2.3 parts by mass of sodium dodecyl sulfate to 3000 parts by mass of ion-exchanged water in a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction apparatus, The internal temperature was raised to 80 ° C. After raising the temperature, 10 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water is added, and the following monomer mixture is added dropwise over 1 hour, followed by heating and stirring at 80 ° C. for 2 hours. Polymerization was performed to prepare resin particles. This is designated as shell resin-containing latex SL-2. The molecular weight and glass transition point measured by drying SL-2 were Mw 41,000, and Tg was 40 ° C.
(Monomer mixture)
Styrene 480 parts by mass n-butyl acrylate 260 parts by mass Methacrylic acid 70 parts by mass n-octyl mercaptan 4 parts by mass

[Production of Toner 5]
Other than changing the UV-curable resin-containing latex UVL-1 to UVL-3 and the shell resin-containing latex SL-1 to SL-2 in the aggregation / fusion process of toner 1 production, “Toner 5” was produced in the same manner as in the production.

[Production of shell resin-containing latex SL-3]
While adding 2.3 parts by mass of sodium dodecyl sulfate to 3000 parts by mass of ion-exchanged water in a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device, stirring at a stirring speed of 230 rpm under a nitrogen stream, The internal temperature was raised to 80 ° C. After raising the temperature, 10 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water is added, and the following monomer mixture is added dropwise over 1 hour, followed by heating and stirring at 80 ° C. for 2 hours. Polymerization was performed to prepare resin particles. This is designated as shell resin-containing latex SL-3. The molecular weight and glass transition point measured by drying SL-3 were Mw 33,000, and Tg was 68 ° C.
(Monomer mixture)
Styrene 600 parts by mass n-butyl acrylate 140 parts by mass Methacrylic acid 70 parts by mass n-octyl mercaptan 3 parts by mass

[Production of Toner 6]
“Toner 6” was produced in the same manner as in the production of toner 1 except that the shell resin-containing latex SL-1 was changed to SL-3 in the aggregation / fusion process of the production of toner 1.

[Evaluation]
Using a developer (toner) obtained as described above, a combination of text and figure patches on glossy resin-coated paper POD-128 with a remodeled machine "bizhubPro C6500" with the fuser unit removed. The unfixed image was output.
Next, the fixed image was obtained by fixing the unfixed image with the bizhubPro C6500 single fixing / UV irradiation tester, which was modified to allow UV irradiation after fixing with the fixing belt of the bizhubPro C6500 fixing device.
The fixing temperature of the fixing belt was fixed at 170 ° C. The UV irradiation tester was exposed for 2 minutes at a wavelength of 365 nm using a UV irradiation tester equipped with an ultraviolet lamp of about 30 mW / cm ² . Radiation temperature was 25-30 degreeC.

(Evaluation item)
1. Scratch strength According to the pencil hardness evaluation method specified in JIS-K-5400, a pencil hardness test (pencil scratch test) is performed with a load of 9.7 N, and mechanical properties are measured with a pencil hardness value at which no scratches are observed on the film surface. evaluated. The results are shown in Table 1 below. As the test pencil, one specified in JIS-S-6006 was used. A pencil hardness of F or higher is a practically acceptable level.

2. Image Gloss Gloss was measured using a gloss meter “Gloss Meter” (manufactured by Murakami Color Engineering Laboratory) at an incident angle of 75 ° based on a glass surface with a refractive index of 1.567. The results are shown in Table 1 below. Note that 60 or higher is a level with no practical problem as a high gloss image.

3. Solvent cloth rubbing The fixed image was abraded and reciprocated with a cloth impregnated with toluene, and the number of reciprocations until the image was blurred or peeled was determined. The results are shown in Table 1 below. Note that there is no practical problem when there is no image blur after 10 reciprocations.

4). Fusing property 2 g of each toner was placed in a sample tube, shaken 500 times with a tapping denser, and allowed to stand in an environment of 50 ° C. and 55% RH for 24 hours. Next, the mixture was put into a 300 μm mesh sieve, sieved under a constant vibration condition, and the ratio of the amount of toner remaining on the mesh after the particles were fused (toner aggregation rate) was measured. Practically, 0 to 10% or less is required as a range in which there is no problem in toner particle fusion. The results are shown in Table 1 below.

5. Low temperature offset avoiding temperature The fixing temperature of the fixing belt was lowered at a rate of 5 ° C. from 170 ° C., and fixing was performed. The results are shown in Table 1 below. In addition, 170 degrees C or less is a level which does not have a practical problem.

In addition, it shows in Table 2 about the mass% with respect to the total amount of a composition, a mass part, and a polymer compound (A) of ultraviolet curable resin containing latex UVL-1 and UVL-3, and a preferable range (mass%). In addition, Table 3 shows the mass% of the ultraviolet curable resin, the core resin, the shell resin, and the mass% of the toner 1 to the toner 6 and the preferable range (mass%).
Further, the glass transition point and molecular weight of the ultraviolet curable resin, the core resin, and the shell resin contained in the toner 1, 4, 5, and 6 and the difference between the glass transition point of the ultraviolet curable resin and the glass transition point of the shell resin (ΔUV− SH) is shown in Table 4.

  From the above results, when toner 1 and toners 4 to 6 are used, compared to the case of using toners 2 and 3 of the comparative example, the scratch strength, image gloss, solvent cloth rubbing, and fusion of the obtained toner image It was favorable in terms of the property and the low temperature offset avoidance temperature. Therefore, by using the toner of the present invention, there is no problem of toner particle fusion during storage or in the developing device, and both high durability and high glossiness of the toner image can be achieved.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 20 Transfer material storage part 30 Document reading part 40 Image forming part 50 Intermediate transfer belt 60 Registration roller 70 Transfer part 80 Fixing device 801 Pressing member 803 Fixing belt 804 Fixing roller 805 Halogen heater 806 Heating rollers 807 and 808 809 Temperature sensor 810 Nip part 101 Heating roller 102 Pressure roller 103 UV irradiation device 104 Light source lamp 105 Reflector 400Y, 400M, 400C, 400K Image forming means 410 Photoconductor 420 Scorotron charging means 430 Exposure means 440 Developing means 450 Cleaning means P Transfer material

Claims (6)

In a toner having a core-shell structure containing at least a resin,
A toner characterized in that a part of the resin contained in the core layer contains an ultraviolet curable resin.   The toner according to claim 1, wherein the ultraviolet curable resin is an ultraviolet curable resin having a photoinitiating functional group that generates radicals by ultraviolet rays in a molecule.   The glass transition point of the ultraviolet curable resin contained in the core layer is lower than the glass transition point of the resin contained in the shell layer, and the glass transition point of the ultraviolet curable resin contained in the core layer; The toner according to claim 1, wherein the difference in glass transition point of the resin contained in the shell layer is 25 to 50 ° C. 4. 4. The ultraviolet curable resin according to any one of claims 1 to 3, wherein the ultraviolet curable resin is an ultraviolet curable resin obtained by addition-reacting the monomer (5) below with the monomers (1) to (4) below. The toner according to claim 1.
(1) Carboxyl group-containing vinyl polymerization monomer (2) Photoinitiating functional group-containing vinyl polymerization monomer (3) Isocyanate group, hydroxyl group or glycidyl group-containing vinyl polymerization monomer (4) Co-polymerized with the monomers (1) to (3) above Other vinyl polymerizable monomers capable of polymerization (5) Vinyl polymerizable monomers containing a reactive functional group capable of reacting with the monomer (3) 71 in a method for producing a toner having a core-shell structure containing at least a resin,
Mixing a dispersion of resin particles containing at least an ultraviolet curable resin and a dispersion of colorant particles, and aggregating the resin particles and the colorant particles to form a core layer;
Coating the core layer with a resin to form a shell layer;
A method for producing a toner, comprising: A charging step for charging at least the photoreceptor;
An exposure step of forming an electrostatic latent image on the photoreceptor;
A developing step of developing the electrostatic latent image with toner;
A transfer step of transferring the toner image on the photoreceptor to a transfer material;
A fixing step of fixing the toner image to the transfer material;
A UV irradiation step of irradiating the toner image after fixing with UV,
The toner has a core-shell structure containing at least a resin;
An image forming method, wherein a part of the resin contained in the core layer contains an ultraviolet curable resin.

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