JP2007178782A - Toner for electrostatic charge image development and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development that can stably obtain a print high in image quality even under a high temperature and high humidity environment, and to provide a method for manufacturing the toner. <P>SOLUTION: The method for manufacturing the toner includes: a step (A) of dispersing a liquid (oil phase) containing a polymerizable monomer for a core in an aqueous dispersion medium to produce liquid drops containing the polymerizable monomer for a core (the liquid drops which are finally to be color resin particles); a step (B) of polymerizing the liquid drops in the aqueous dispersion medium to produce core particles; and a step (C) of adding a polymerizable monomer for a shell layer containing a styrene sulfonic acid ester compound expressed by formula (1) and polymerizing to form a shell layer, wherein each of R<SP>1</SP>and R<SP>2</SP>independently represents a substituent selected from a hydrogen atom, an alkyl group and an alkenyl group, and R<SP>3</SP>represents an alkyl group or an alkenyl group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrostatic charge image developing toner used for developing an electrostatic latent image or the like in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like, and a method for producing the same. Hereinafter, the “electrostatic charge image developing toner” may be simply referred to as “toner”.

A method of forming a desired image by developing an electrostatic latent image with toner for developing an electrostatic image is widely used.
For example, in electrophotography, an electrostatic latent image formed on a photoconductor is developed with a toner obtained by blending colored particles with other particles such as an external additive or a carrier as required, and then a paper or an OHP sheet. Then, the toner is fixed to obtain a printed matter.

In recent years, there has been a growing need for colorization of image forming apparatuses such as multifunction machines, facsimiles, and printers using electrophotography. In color printing, since images such as photographs that require high-resolution and clear tone reproduction are also printed, color toners that can meet these requirements are demanded.
As an example of an image forming method in the case of color copying (color copying), first, a color original is decomposed and read into a large number of pixels, and light is applied to a charged photoconductor as a color-specific digital image signal. An electrostatic latent image is formed. Next, the electrostatic latent image is developed with a color toner corresponding to the electrostatic latent image for each color to form a toner image, which is transferred to a recording material such as paper or an OHP sheet. The transferred toner image is fixed on the recording material by a method such as heating and pressing.

In general, toners are roughly classified into those produced by a pulverization method and a polymerization method.
The pulverization method produces colored resin particles by a method of pulverizing and classifying solids of a colored resin obtained by a method of melt-kneading a binder resin and a colorant or a method of polymerizing a mixture containing a monomer and a colorant. To do.
On the other hand, the polymerization method is, for example, a suspension polymerization method in which droplets of a polymerizable monomer composition containing a polymerizable monomer and a colorant are formed, and the droplets are polymerized to produce colored resin particles. An emulsion polymerization aggregation method in which an emulsified polymerizable monomer is polymerized to obtain resin fine particles and aggregated with a colorant or the like to produce colored resin particles. The colored resin particles obtained by the pulverization method are indefinite, whereas the colored resin particles obtained by the polymerization method are almost spherical and have a small particle size and a sharp particle size distribution.
In particular, from the viewpoint of improving image quality such as image reproducibility and fineness, a toner whose shape and particle size distribution are highly controlled is used, such as a toner obtained by a polymerization method (so-called polymerization method toner). It has become.

The electrostatic image developing toner is supplied to a photosensitive member having an electrostatic latent image after being charged between toner particles and a developing device member such as a developing blade, toner particles or between toner particles and a carrier. .
A moderately charged toner adheres to the photoreceptor in an amount corresponding to the charge density of the electrostatic latent image, and can form a high-quality image. On the other hand, when the charging characteristics such as the toner charge amount or charging uniformity are inappropriate, a high-quality image cannot be formed.
Accordingly, the toner for developing an electrostatic image is usually prepared by dissolving or uniformly dispersing a charge control agent or a charge control resin in the toner particles in order to impart sufficient chargeability.

Patent Document 1 discloses an electrophotographic toner characterized by containing one or more compounds having a sulfonic acid ester moiety.
However, the toner disclosed in the example of Patent Document 1 shows a method for producing a toner by a pulverization method in which a binder resin, a charge control agent, a colorant and the like are melt-kneaded and the obtained kneaded material is pulverized. In addition, when the toner is manufactured by the pulverization method, the charge control agent is present at the same concentration on the inner side and the outer side in the toner particles. Therefore, in order to obtain a desired toner charge amount, a large amount of charge control is performed. It is necessary to add an agent. As a result, the environmental stability of the toner may be reduced.

In Patent Document 2, after dispersing the charge control agent in the aqueous phase, the granulation step (droplet formation step) of the oil phase obtained by dispersing at least the polymerizable monomer, the colorant and the polymerization initiator is performed. A method for producing a polymerized toner is disclosed. In this step, a part of the charge control agent in the aqueous phase can be put into the oil phase.
Patent Document 2 discloses that the charge control agent is a metal complex of an organic compound having a sulfonate ester or a metal-containing dye.
However, in Patent Document 2, since the compatibility of these charge control agents with the binder resin is poor, the charge control agent existing in a form that is free to adhere to the toner surface is easily detached, and the charge amount of the toner is increased. In addition to causing variations, filming is likely to occur in members in the developing device such as a photoconductor.
In Patent Document 2, since a highly hydrophilic charge control agent is present on the toner surface, the surface of the toner particles easily absorbs moisture, particularly in a high-temperature and high-humidity environment, and the environmental stability and chargeability of the toner are reduced. May cause.

On the other hand, in order to uniformly disperse the polar functional group capable of imparting charging property in the colored resin particles, a toner using a copolymer containing a polar functional group as a binder resin has been studied.
In Patent Document 3, an aqueous phase and an oil phase obtained by dispersing a monomer having a polar functional group or a polymer having a polar functional group are supplied to a granulator to obtain a suspension having polymerizable droplets. A method for producing a toner having the following is disclosed. Patent Document 3 describes that the monomer having a polar functional group is sodium styrenesulfonate.
Patent Document 3 focuses on improving the dispersibility of a colorant by adding a monomer or a polymer having a polar functional group, not the dispersibility of a polar functional group that imparts chargeability. In addition, since sodium styrenesulfonate has high hydrophilicity, the obtained toner easily absorbs moisture, and there is a risk that the environmental stability in a high temperature and high humidity environment may be lowered.

On the other hand, a toner in which polar functional groups imparting charging properties are uniformly present on the surface has been studied.
Patent Document 4 discloses a toner characterized in that a polymer containing a sulfonic acid group-containing vinyl monomer as a monomer component is attached to the surface of capsule particles.
Patent Document 5 discloses an electrostatic charge developing toner characterized in that the surface of colored particles (core particles) is coated with a coating layer composed of a release agent and a charge-controllable thermoplastic resin. It is described that the controllable plastic resin is obtained by reacting a sulfonic acid group with a fluorine-containing quaternary ammonium salt.
Patent Document 6 discloses a toner production method including a step of forming a toner particle by adding a polymerizable monomer and a sulfur-containing polymer and coating a shell portion on the surface of a core particle by seed polymerization, It is described that the sulfur-containing polymer contains a sulfonic acid group-containing vinyl monomer as a monomer component.

  However, a toner having a shell layer made of a vinyl monomer containing a sulfonic acid group or a salt group thereof used in Patent Documents 4 to 6 or a binder resin containing a repeating unit derived from the polymer, In a high temperature and high humidity environment, moisture is likely to be adsorbed to the toner, which may reduce environmental stability.

JP 7-36221 A JP-A-7-199535 JP-A-7-199536 JP-A-6-230598 JP-A-6-332229 JP 2003-330225 A

  The present invention has been made in view of the above circumstances, and is capable of stably maintaining high-quality printing even under high temperature and high humidity, and for electrostatic image development excellent in environmental stability and charging stability. The object is to provide toner.

The inventors of the present invention have intensively studied to achieve the above object, and as a result, a shell layer polymerizable compound containing a styrene sulfonate compound in an aqueous dispersion medium in which core particles containing a binder resin and a colorant are dispersed. A toner having a core-shell structure coated with a shell layer containing a binder resin, which is a polymer of the polymerizable monomer for the shell layer, by adding a monomer and polymerizing the same, and a method for producing the same have the above objects The knowledge that it can be achieved was obtained.
The present invention has been made based on the above findings, and is a colored resin having a core-shell structure in which core particles containing a first binder resin and a colorant are coated with a shell layer containing a second binder resin. In the method for producing a toner for developing an electrostatic image containing particles,
A liquid containing the core polymerizable monomer (oil phase) is dispersed in an aqueous dispersion medium, and a liquid droplet containing the core polymerizable monomer (a liquid droplet that finally becomes colored resin particles) In the aqueous dispersion medium in which the droplets are polymerized in the aqueous dispersion medium to form core particles, and in the aqueous dispersion medium in which the core particles are dispersed, styrene represented by the formula (1) The present invention provides a method for producing a toner for developing an electrostatic charge image, comprising the step C of forming a shell layer by adding a polymerizable monomer for a shell layer containing a sulfonate compound and polymerizing the monomer. .

(Wherein R ¹ and R ² each independently represent a substituent selected from a hydrogen atom, an alkyl group, or an alkenyl group. R ³ represents an alkyl group or an alkenyl group.)

  In the toner for developing an electrostatic image provided by the production method of the present invention, polar functional groups imparting chargeability are uniformly dispersed in the shell layer of the core-shell type colored resin particles, and particularly in an environment of high temperature and high humidity. Since it is hardly affected by moisture even under the surface, it has excellent charging stability and environmental stability.

  In the method for producing a toner for developing an electrostatic charge image according to the present invention, since the toner can be provided with appropriate chargeability and excellent in environmental stability, the styrenesulfonic acid represented by the formula (1) The amount of the ester compound is preferably 0.1 to 5.0% by weight based on 100 parts by weight of the monovinyl monomer in the core polymerizable monomer.

  In the method for producing a toner for developing an electrostatic charge image according to the present invention, in the step A, the droplets preferably contain the polymerizable monomer for the core and a colorant.

According to the present invention, electrostatic image development containing colored resin particles having a core-shell structure in which core particles containing a first binder resin and a colorant are coated with a shell layer containing a second binder resin. For toner,
The second binder resin contains a copolymer containing a repeating unit derived from a styrene sulfonate compound represented by the following formula (1), whereby an electrostatic charge image developing toner is obtained.

（式中、Ｒ^１、及びＲ^２はそれぞれ独立に水素原子、アルキル基、又はアルケニル基から選ばれる置換基を表す。また、Ｒ^３はアルキル基、又はアルケニル基を表す。）

(Wherein R ¹ and R ² each independently represent a substituent selected from a hydrogen atom, an alkyl group, or an alkenyl group. R ³ represents an alkyl group or an alkenyl group.)

  Further, in the present invention, the colored resin particles are obtained by dispersing a liquid (oil phase) containing a core polymerizable monomer in an aqueous dispersion medium to form droplets containing the core polymerizable monomer ( Finally forming droplets to be colored resin particles), forming the core particles by polymerizing the droplets in the aqueous dispersion medium, and the aqueous dispersion medium in which the core particles are dispersed. It is manufactured by adding a polymerizable monomer for the shell layer containing the styrene sulfonate compound represented by the formula (1) and polymerizing it to form a shell layer. A toner for developing an electrostatic charge image can be obtained.

  In the present invention, the amount of the styrene sulfonate compound represented by the formula (1) is 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the monovinyl monomer in the core polymerizable monomer. The electrostatic image developing toner can be obtained.

  In the present invention, in the step A, the droplets are formed by dispersing the polymerizable monomer composition containing the polymerizable monomer for the core and the colorant in an aqueous dispersion medium. A toner can be obtained.

  The toner for developing an electrostatic charge image provided by the present invention can have an adsorbed water amount in the range of 0.05 to 0.3% by weight at 32 ° C. and a relative humidity of 80%. When the adsorbed moisture content of the toner at a temperature of 32 ° C. and a relative humidity of 80% satisfies the above range, it is possible to suppress a decrease in charging stability and environmental stability particularly in a high temperature and high humidity environment.

  In the electrostatic image developing toner according to the present invention, the thickness of the shell layer is preferably 5 to 1000 nm.

  In order to sufficiently obtain environmental stability and charge stability, which are the effects of the present invention, the core particles preferably do not contain a charge control agent.

  The toner for developing an electrostatic charge image of the present invention as described above is excellent in environmental stability without causing fogging even in a high-temperature and high-humidity environment, and can perform high-quality printing with high image density.

The method for producing a toner for developing an electrostatic charge image according to the present invention includes: a core resin having a core-shell structure in which core particles containing a first binder resin and a colorant are coated with a shell layer containing a second binder resin. In the method for producing a toner for developing an electrostatic image containing particles,
A liquid containing the core polymerizable monomer (oil phase) is dispersed in an aqueous dispersion medium, and a liquid droplet containing the core polymerizable monomer (a liquid droplet that finally becomes colored resin particles) Forming a core particle by polymerizing the droplets in the aqueous dispersion medium, obtaining an aqueous dispersion medium in which the core particles are dispersed, and an aqueous dispersion in which the core particles are dispersed The process includes a step C in which a shell layer is formed by adding a polymerizable monomer for a shell layer containing a styrene sulfonate compound represented by the formula (1) to the medium to form a shell layer. is there.

(Wherein R ¹ and R ² each independently represent a substituent selected from a hydrogen atom, an alkyl group, or an alkenyl group. R ³ represents an alkyl group or an alkenyl group.)

In conventional toners, when a toner (liquid phase) containing a charge control agent or a charge control resin having a polar functional group together with a polymerizable monomer is dispersed in an aqueous dispersion medium, these are highly hydrophilic. Spherical droplets are likely to become unstable in an aqueous dispersion medium, and colored resin particles with a wide particle size distribution are easily obtained. Further, the charge control agent and charge control resin are very shallow from the surface of the colored resin particles. Is unevenly distributed.
The charging phenomenon of the toner mainly occurs on the surface of the toner particle. When the polar functional group having high hydrophilicity is unevenly distributed on the surface of the colored resin particle, the toner is easily affected by temperature and humidity. When the amount of water on the surface of the colored resin particles changes with environmental changes such as temperature and humidity, the charging characteristics of the toner are likely to fluctuate due to the influence. If the toner charging characteristics fluctuate and the toner charge amount decreases or becomes non-uniform, desired development corresponding to the electrostatic latent image on the photosensitive member cannot be performed, resulting in insufficient image density, unevenness, or fogging. Cause problems. Further, when the charge control agent or charge control resin is unevenly distributed on the surface, the toner is likely to deteriorate due to the external additive being embedded in the toner due to friction with the developing member, etc. descend.

On the other hand, in the present invention, since no charge control agent or charge control resin containing a polar functional group is used when preparing the core particles, the droplets are relatively stable even in an aqueous dispersion medium. Colored resin particles having a sharp distribution can be prepared.
In addition, the sulfonic acid ester group in the styrene sulfonic acid ester compound used in the present invention is generally higher in a high temperature and high humidity environment than a sulfonic acid group or salt thereof known as a polar substituent that imparts chargeability. It is considered that the effect of toner moisture adsorption on the charging stability of the toner is reduced, and the charge characteristics of the obtained toner, such as the charging amount or the charging uniformity, are maintained in an appropriate state.
Furthermore, as a result of investigations by the present inventors, the toner provided by the present invention is such that the polar functional group imparting charging properties derived from the styrene sulfonate compound is uniformly dispersed on the surface of the colored resin particles. It has been found that toner deterioration due to friction with the developing member is reduced.

Examples of the polymerization method for the core polymerizable monomer composition include a suspension polymerization method and an emulsion polymerization aggregation method. The core particles according to the present invention are preferably polymerized by a suspension polymerization method. .
In the method for producing core particles by the suspension polymerization method, first, the core polymerizable monomer composition containing the core polymerizable monomer and the colorant as essential components is prepared, and the obtained core component is obtained. A first binder resin and a colorant are obtained by dispersing the polymerizable monomer composition in an aqueous dispersion medium and polymerizing the polymerizable monomer composition in a state where droplets of the polymerizable monomer composition for the core are formed. A core particle containing is obtained.
Hereinafter, a method for producing an electrostatic charge image developing toner according to the present invention will be described in order.

(1) Step A for forming droplets containing a polymerizable monomer for core
First, a polymerizable monomer composition for a core is prepared by mixing a polymerizable monomer for a core, which is a raw material for the first binder resin, a colorant, and other additives as required. The colorant and other additives are preferably mixed so that they are dissolved or dispersed as uniformly and finely as possible in the core polymerizable monomer. In order to perform such mixing, it is preferable to use a media type disperser.

In the present invention, the polymerizable monomer refers to a polymerizable compound.
It is preferable to use a monovinyl monomer as the main component of the polymerizable monomer for the core. Examples of the monovinyl monomer include styrene; styrene derivatives such as vinyl toluene and α-methylstyrene; acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid 2 Acrylic esters such as ethylhexyl and dimethylaminoethyl acrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and dimethylaminoethyl methacrylate; acrylamide Amide compounds of acrylic acid such as methacrylamide, amides of methacrylic acid; olefins such as ethylene, propylene and butylene; halogens such as vinyl chloride, vinylidene chloride and vinyl fluoride Vinyl esters such as vinyl acetate and vinylidene halides; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone and methyl isopropenyl ketone; 2-vinyl pyridine, 4 -Nitrogen-containing vinyl compounds such as vinyl pyridine and N-vinyl pyrrolidone; These monovinyl monomers may be used alone or in combination. Of these, styrene, styrene derivatives, and acrylic acid or methacrylic acid derivatives are preferably used as monovinyl monomers.
The proportion of the monovinyl monomer is preferably at least 80% by weight or more in the core polymerizable monomer used to form the first binder resin component.

As a part of the polymerizable monomer for the core, it is preferable to use any crosslinkable polymerizable monomer together with the monovinyl monomer in order to improve hot offset. A crosslinkable polymerizable monomer means a monomer having two or more polymerizable functional groups. Examples of the crosslinkable polymerizable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; diacrylate compounds such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; N, N-divinyl. Other divinyl compounds such as aniline and divinyl ether; compounds having three or more vinyl groups; These crosslinkable polymerizable monomers can be used alone or in combination of two or more.
In the present invention, the crosslinkable polymerizable monomer is usually used at a ratio of 0.1 to 5 parts by weight, preferably 0.3 to 2 parts by weight, with respect to 100 parts by weight of the monovinyl monomer. desirable.

Furthermore, it is preferable to use a macromonomer as a part of the polymerizable monomer for the core because the balance between the storage stability and the fixing property at low temperature becomes good. The macromonomer has a polymerizable carbon-carbon unsaturated double bond at the end of the molecular chain, and is a reactive oligomer or polymer having a number average molecular weight of usually 1,000 to 30,000.
The macromonomer is preferably one that gives a polymer having a higher Tg than the Tg of the polymer obtained by polymerizing the monovinyl monomer. The amount of the macromonomer is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, and more preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the monovinyl monomer.

  In the present invention, a colorant is used. However, when a color toner (usually, four types of toners of black toner, cyan toner, yellow toner, and magenta toner are used), a black colorant, a cyan colorant, and a yellow toner are used. A colorant and a magenta colorant can be used, respectively.

  In the present invention, pigments such as carbon black and titanium black can be used as the black colorant.

  As the cyan colorant, for example, a copper phthalocyanine compound, a derivative thereof, and an anthraquinone compound can be used. Specifically, C.I. I. Pigment Blue 2, 3, 6, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17, 17: 1 and 60, etc. Is stable and has coloring power. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 17: 1, and the like, preferably copper phthalocyanine compounds such as C.I. I. Pigment Blue 15: 3 is more preferable.

  As the yellow colorant, for example, azo pigments such as monoazo pigments and disazo pigments, and compounds such as condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Yellow 3, 12, 12, 13, 15, 17, 62, 65, 73, 74, 83, 93, 97, 120, 138, 155, 180, 181, 185, 186, 213, and the like.

  Examples of the magenta colorant include compounds such as monoazo pigments, azo pigments such as disazo pigments, and condensed polycyclic pigments. Specifically, C.I. I. Pigment Red 31, 48, 57: 1, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 149, 150, 163, 170, 184, 185, 187, 202, 206, 207, 209, 251 and C . I. Pigment Violet 19 etc. are mentioned. Since the polymerization stability is good and there is coloring power, C.I. I. Pigment Red 31, 48, 57: 1, 58, 60, 63, 64, 68, 112, 114, 146, 150, 163, 170, 185, 187 Monoazo pigments such as No. 206 and No. 207 are also preferred.

  The amount of each colorant added is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the monovinyl monomer.

  In the present invention, the polymerizable monomer for the shell layer, which is the raw material for the second binder resin, contains a polar functional group that imparts charging properties derived from the styrene sulfonate compound, thereby resulting in environmental stability. In order to obtain sufficient charge stability, it is not necessary to include a charge control agent in the core particles or the colored resin particles. However, a charge control agent may be contained in the core particles or the colored resin particles.

  It is preferable to use a molecular weight modifier as another additive. Examples of molecular weight modifiers include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and 2,2,4,6,6-pentamethylheptane-4-thiol. The molecular weight modifier can be added before the start of polymerization or during the polymerization. The amount of the molecular weight modifier is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, with respect to 100 parts by weight of the monovinyl monomer.

  Moreover, in this invention, it is preferable to use an aluminum coupling agent as another additive. Since the aluminum coupling agent can modify the surface of the colorant particles and enhance the dispersibility of the colorant, it becomes easy to control the amount of adsorbed moisture described later within the specified range of the present invention.

  The core particles according to the present invention preferably contain a release agent. Examples of the release agent include polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; natural waxes such as candelilla, carnauba, rice, wood wax, and jojoba; paraffin, microcrystalline, and petrolactam Petroleum wax and modified wax thereof; synthetic wax such as Fischer-Tropsch wax; pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrapalmitate, dipentaerythritol hexamyristate, dipentaerythritol hexastearate, etc. And the like. These can be used alone or in combination of two or more.

Among the above release agents, the endothermic peak temperature is 30 to 150 ° C., preferably 50 to 120 ° C., measured from the DSC curve at the time of temperature increase at a temperature increase rate of 10 ° C./min using a differential scanning calorimeter. More preferably, a polyhydric alcohol esterified product such as pentaerythritol ester in the range of 60 to 100 ° C. or dipentaerythritol ester having the same endothermic peak temperature in the range of 50 to 80 ° C. is used in terms of the fixing-peeling balance. Particularly preferred.
The amount of the release agent is usually 0.5 to 50 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the monovinyl monomer.

  In the method for producing a toner for developing an electrostatic charge image according to the present invention, it is preferable to uniformly disperse and refine the colorant particles. As a method for dispersing and refining the colorant particles, it is preferable to perform a dispersion step on the mixture containing at least the polymerizable monomer for the core and the colorant. Specifically, the colorant particles and the monovinyl monomer, and further part of other components, such as an aluminum coupling agent, are preliminarily dispersed by an emulsifying disperser or the like, and further dispersed by a media type disperser. Furthermore, the other component contained in the polymerizable monomer composition for the core is added to obtain the polymerizable monomer composition. By performing the dispersion step, it is easy to control the amount of adsorbed moisture of the toner to be described later within a specified range.

  In the present invention, the polymerizable monomer composition obtained as described above is preferably dispersed in an aqueous dispersion medium containing a dispersion stabilizer, and after adding a polymerization initiator, the polymerizable monomer composition Form droplets of objects. The method for forming droplets is not particularly limited. For example, an in-line type emulsifying disperser (manufactured by Ebara Seisakusho, trade name “Ebara Milder”), a high-speed emulsifier / disperser (made by Tokushu Kika Kogyo Co., Ltd., trade name “TK”). .. Homomixer MARK type II)) etc.

  In the present invention, the aqueous dispersion medium may be water alone, but a solvent that is soluble in water may be used in combination. Examples of the solvent that can be dissolved in water include lower alcohols such as methanol, ethanol, and isopropanol, and lower ketones such as dimethylformamide, tetrahydrofuran, acetone, and methyl ethyl ketone.

In the present invention, the aqueous dispersion medium preferably contains a dispersion stabilizer. Examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide; Inorganic compounds that can be dissolved in acids or alkalis such as metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide. Furthermore, organic compounds such as water-soluble polymers such as polyvinyl alcohol, methylcellulose, and gelatin; anionic surfactants; nonionic surfactants; amphoteric surfactants; The said dispersion stabilizer can be used 1 type or in combination of 2 or more types.
Among the above dispersion stabilizers, dispersion stabilizers containing colloids of metal compounds, particularly poorly water-soluble metal hydroxides, can narrow the particle size distribution of the colored resin particles, and the dispersion stabilizer remains after washing. Since the amount is small, the obtained polymerized toner is preferable because the image can be clearly reproduced and the environmental stability is not deteriorated.
The dispersion stabilizer is used in an amount of 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the aqueous dispersion medium.

In the present invention, examples of the polymerization initiator for polymerizing the polymerizable monomer composition for the core include persulfates such as potassium persulfate and ammonium persulfate; 4,4′-azobis (4-cyanovaleric Acid), 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2, 4-dimethylvaleronitrile) and azo compounds such as 2,2′-azobisisobutyronitrile; di-t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t -Hexylperoxy-2-ethylhexanoate, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, di-t-butylper Carboxylate isophthalate, and t- butyl peroxide peroxy isobutyrate and the like. Moreover, you may use the redox initiator which combined the said polymerization initiator and the reducing agent. Among these, it is preferable to use a peroxide because residual polymerizable monomers can be reduced and printing durability is good.
As described above, the polymerization initiator may be added after the polymerizable monomer composition for the core is dispersed in the aqueous dispersion medium and before the droplet formation. It may be added to the composition.
The addition amount of the polymerization initiator used for the polymerization of the polymerizable monomer composition for the core is preferably 0.1 to 20 parts by weight, more preferably 0 to 100 parts by weight of the monovinyl monomer. 3 to 15 parts by weight, and most preferably 1.0 to 10 parts by weight.

(2) Process B for forming core particles
As described above, droplets of the polymerizable monomer composition for the core are formed, and the obtained aqueous dispersion medium is heated to start polymerization.
The polymerization temperature of the core polymerizable monomer composition is preferably 50 ° C. or higher, more preferably 60 to 95 ° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.

(3) Step C for forming the shell layer
The colored resin particles according to the present invention are so-called core-shell type (or “capsule type”) particles obtained by combining two different polymers inside (core particles) and outside (shell layer) of the particles. To do. In the core-shell type colored resin particles, the low-softening point material in the inside (core layer) is coated with a material having a higher softening point to balance the lowering of the minimum fixing temperature and the storage stability of the toner. it can.
In the present invention, the shell layer is composed only of the second binder resin containing a copolymer containing a repeating unit derived from the styrene sulfonic acid ester compound represented by the above formula (1). May further be contained.
The core-shell type colored resin particles can coat the shell layer on the surface of the core particles obtained by the above-described method by a conventionally known method, but in situ polymerization method is preferable from the viewpoint of production efficiency.
Hereinafter, a method for producing core-shell type colored resin particles by an in situ polymerization method will be described.

When the core particles obtained by the above polymerization method are coated with a shell layer by an in situ polymerization method, the styrene sulfonate compound represented by the above formula (1) is added to the aqueous dispersion medium in which the core particles are dispersed. By adding and polymerizing the polymerizable monomer for shell layer and the polymerization initiator for shell layer, core-shell type colored resin particles can be obtained.
As a specific method for forming the shell layer, a polymerizable monomer for shell layer containing a styrene sulfonate compound represented by the above formula (1) in a reaction system of a polymerization reaction performed to obtain core particles. And a method of continuously polymerizing by adding a polymerization initiator for the shell layer, and polymerizing the polymerizable monomer composition for the core in another reaction system, and further associating and then filtering, washing, dehydrating, and drying The core particle obtained in this way is charged into an aqueous dispersion medium, and a shell layer polymerizable monomer and a polymerization initiator are added to the core particle, followed by stepwise polymerization.

  As the polymerizable monomer for the shell layer, the same monomers as the above-mentioned core polymerizable monomer can be used. Among these, it is preferable to use monomers such as styrene, acrylonitrile, and methyl methacrylate that can yield a polymer having a Tg exceeding 80 ° C. alone or in combination of two or more.

  In this invention, the styrene sulfonic acid ester compound represented by following formula (1) is included other than the said monomer as a polymerizable monomer for shell layers which is a raw material of 2nd binder resin. When the repeating unit derived from the styrene sulfonate compound represented by the following formula (1) is contained in the second binder resin, the obtained toner is imparted with appropriate chargeability, and also has environmental stability. Excellent.

(Wherein R ¹ and R ² each independently represent a substituent selected from a hydrogen atom, an alkyl group, or an alkenyl group. R ³ represents an alkyl group or an alkenyl group.)

The styrene sulfonate ester represented by the above formula (1) is not particularly limited as long as it satisfies the above structure, but R ¹ and R ² in the formula (1) are each independently a hydrogen atom, a methyl group, ethyl It is preferably a substituent selected from a group, a propyl group, an isopropyl group, and a butyl group, and R ³ is preferably an alkyl group, and is a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group. More preferably. More specifically, examples include methyl p-styrene sulfonate, ethyl p-styrene sulfonate, propyl p-styrene sulfonate, and the like.

These styrene sulfonic acid ester compounds may be used alone or in combination. The ratio of the styrene sulfonic acid ester compound represented by the above formula (1) is about 0.1 parts by weight with respect to 100 parts by weight of the monovinyl monomer in the core polymerizable monomer used to form the binder resin component. The amount is preferably 1 to 5.0 parts by weight, and more preferably 0.3 to 3 parts by weight.
If the proportion of the styrene sulfonate compound is less than the above range, the content of polar substituents imparting chargeability is too small, so that a sufficient charge amount cannot be imparted to the toner.
On the other hand, if the ratio of the styrene sulfonate compound is larger than the above range, the toner charge amount becomes excessive, so that the durable printability is lowered.
Moreover, it is preferable that the polymerization conversion rate of the polymerizable monomer composition for the core is 50% or more, and more preferably 55 to 90% for the timing suitable for adding the styrene sulfonate compound. .

  The styrene sulfonic acid ester compound represented by the above formula (1) can be prepared, for example, by reacting the corresponding styrene sulfonyl chloride with an alkyl or alkenyl alcohol in the presence of a base in an organic solvent. . It can also be prepared by dehydrating condensation of the corresponding styrene sulfonic acid and an alkyl or alkenyl alcohol.

  Alternatively, the core particles may be coated with a binder resin containing a repeating unit derived from styrene sulfonyl chloride or styrene sulfonic acid corresponding to the above formula (1) by in situ polymerization, and esterified by the above method, A second binder resin containing a repeating unit derived from the styrene sulfonate ester represented by the above formula (1) to be the shell layer can be prepared.

  The second binder resin containing the styrene sulfonate compound represented by the above formula (1) of the present invention typically contains a structural unit represented by the following formula (2). The structural unit represented by (3) may be included.

(Wherein R ¹ and R ² each independently represent a substituent selected from a hydrogen atom, an alkyl group, or an alkenyl group. R ³ represents an alkyl group or an alkenyl group.)

(In the formula, R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, or an alkenyl group. In the formula (3),

Is a structure derived when R ³ in the above formula (1) is an alkenyl group, R ′ represents a divalent hydrocarbon group or a single bond, R ″, R ′ ″, and R ′ '''' Each independently represents a hydrogen atom or an alkyl group. )

  As a polymerization initiator used for polymerization of the polymerizable monomer for the shell layer, potassium persulfate and persulfate metal salts such as ammonium persulfate; 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) ) Propionamide], and azo initiators such as 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) 2-hydroxyethyl] propionamide}; An agent can be mentioned. The amount of the polymerization initiator is preferably 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer for shell layer.

  The polymerization temperature of the shell layer is preferably 50 ° C. or higher, more preferably 60 to 95 ° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.

In the present invention, the thickness of the core-shell type shell layer is preferably 5 to 1000 nm, more preferably 20 to 200 nm. When the thickness of the shell layer is within the above range, a toner excellent in charging stability such as charging uniformity can be obtained.
When the thickness of the shell layer is larger than the above range, the minimum fixing temperature of the toner becomes too high or the mechanical strength is too high, so that the toner fixing property may be lowered. On the other hand, when the thickness of the shell layer is less than the above range, the toner is likely to be blocked, so that the storage stability may be lowered. The thickness of the shell layer is determined so that the specific gravity of the polymerizable monomer for the core and the polymerizable monomer for the shell layer is the same. It can be calculated from the following formula from the weight ratio with the second binder resin constituting and the volume average particle diameter of the core-shell colored resin particles. In the following formula, the polymerizable monomer is a raw material for the binder resin of the core particle and the shell layer, and is mainly a monovinyl monomer, a crosslinkable monomer, a macromonomer, and the above formula (1). Is a styrene sulfonate compound represented by the formula:

(4) Filtration, washing, dehydration, and drying In the present invention, the aqueous dispersion of the core-shell colored resin particles obtained by the above-described steps requires filtration, washing, dehydration, and drying operations to remove the dispersion stabilizer. It is preferably repeated several times accordingly.
Also, by performing these operations, the amount of adsorbed water at a temperature of 32 ° C. and a relative humidity of 80% of the electrostatic image developing toner of the present invention described later can be adjusted within a preferred range.

  In the case where an acid-soluble one is used as the dispersion stabilizer, it is preferable to add an acid so that the pH of the aqueous dispersion of colored resin particles is 6.5 or less, more preferably 6 or less. Like that. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid, and organic acids such as formic acid and acetic acid can be used, but because the removal efficiency is large and the burden on the production equipment is small, In particular, sulfuric acid is preferred.

(5) Colored resin particles Through the above manufacturing method, the first binder resin and the core particles containing the colorant are used as the second binder resin, and the styrene sulfonate ester represented by the following formula (1) Colored resin particles having a core-shell structure coated with a shell layer containing a copolymer containing a repeating unit derived from a compound are obtained (the following colored resin particles refer to core-shell type colored resin particles). .

(Wherein R ¹ and R ² each independently represent a substituent selected from a hydrogen atom, an alkyl group, or an alkenyl group. R ³ represents an alkyl group or an alkenyl group.)

The toner for developing an electrostatic charge image of the present invention containing the colored resin particles having the core-shell type structure as described above has an adsorbed water amount of 0.05 to 0.3% by weight at a temperature of 32 ° C. and a relative humidity of 80%, preferably It can be 0.05 to 0.28% by weight.
When the amount of adsorbed moisture at the temperature of 32 ° C. and the relative humidity of 80% is larger than the above range, the charge amount under high temperature and high humidity conditions decreases.
In the present invention, magnetic toner mixed with magnetic powder such as ferrite and iron powder has a large specific gravity. Therefore, the specific gravity is absorbed when converted to a value equivalent to the specific gravity of a pigment such as carbon black. It is preferable that the water content falls within the above range.

In the present invention, the “adsorbed water amount” does not specify the water content of the entire toner particles but specifies the amount of water adsorbed on the surface of the toner particles. The toner is left in a state close to 0 (humidity 0.7% or less in the present invention), and the toner is left at a humidity of 80% on the basis of the weight when it is in a stable state with no weight change. Alternatively, the weight of the toner when it is desorbed and becomes stable with no change in weight again is measured, and the amount of change in the toner weight after the change in environment from the reference weight of the toner is expressed as a percentage of the reference weight. .
The moisture adsorbed on the toner surface may remain on the toner surface even under conditions where the humidity is almost 0%. However, the moisture remaining on the toner surface under this condition Since it is very small, it can be ignored in the present invention.

  The amount of adsorbed moisture can be measured by the following method using an adsorption / desorption measuring device such as IGAsorb Moisture Sorption Analyzer (trade name, manufactured by HIDEN ANALYTIC).

The toner for developing an electrostatic charge image containing the colored resin particles according to the present invention has a toner charge amount Q / on the surface of the developing roll (portion represented by 9 in FIG. 1) at a temperature of 32 ° C. and a relative humidity of 80%. M is preferably −10 to −40 μC / g, and more preferably −15 to −35 μC / g.
The toner for developing an electrostatic charge image of the present invention preferably has a toner charge amount Q / M on the surface of the developing roll at a temperature of 10 ° C. and a relative humidity of 20% of −30 to −60 μC / g, and −35. More preferably, it is -55microC / g.
Here, the toner charge amount Q / M on the surface of the developing roll is a charge amount per unit weight of the toner attached on the developing roll after the exposure process and before the developing process in the use state. The amount of toner charged on the surface of the developing roll is determined by charging the toner developed on the developing roll after the first solid printing is performed using a printer and then the second solid printing is stopped halfway. The amount (μC / g) can be measured using, for example, a suction-type charge measuring device (trade name “210HS-2A” manufactured by Trek Japan Co., Ltd.).

The toner for developing an electrostatic charge image containing the colored resin particles according to the present invention includes the low-temperature and low-humidity environment (temperature 10 ° C. and relative humidity 20%) and the high-temperature and high-humidity environment (temperature 32 ° C. and relative humidity 80%). The ratio of toner charge on the surface of the developing roll (toner charge at 10 ° C. and 20% relative humidity / toner charge at 32 ° C. and 80% relative humidity) is preferably 1.1 to 3.5, more preferably Is 1.3-3.0.
When the toner charge amount ratio exceeds the above range, fogging occurs in a high-temperature and high-humidity environment, and printing stains occur in a low-temperature and low-humidity environment.

  In the present invention, the volume average particle diameter (Dv) of the colored resin particles is preferably adjusted to 3 to 10 μm, and more preferably 5 to 8 μm. If Dv is less than the above range, the fluidity of the toner becomes small, fogging may occur, transfer residue may occur, and cleaning properties may deteriorate. On the other hand, if Dv exceeds the above range, fine line reproducibility may be deteriorated and high image quality may not be achieved, or fixability may be deteriorated.

  The ratio Dv / Dp between the volume average particle diameter (Dv) and the number average particle diameter (Dp) is preferably 1.0 to 1.25, more preferably 1.0 to 1.20. When the ratio Dv / Dp is out of the above range, there are cases where blurring occurs when printing is performed using the obtained polymerized toner, and transferability, printing density and resolution are reduced.

The average circularity (Ca) of the colored resin particles is preferably 0.975 to 0.995, and more preferably 0.980 to 0.990. When the average circularity is within this range, an image excellent in fine line reproducibility can be obtained.
In the present invention, the circularity is defined as a value obtained by dividing the circumference of a circle having the same projected area as the particle image by the circumference of the projected image of the particle. Further, the circularity is used as a simple method for quantitatively expressing the shape of the particles, and is an index indicating the degree of unevenness of the colored resin particles, and the average circularity is a perfect spherical shape of the colored resin particles. 1 is shown in the case, and the value becomes smaller as the surface shape of the colored resin particles becomes more complicated. For the average circularity (Ca), first, the circularity (Ci) of each particle measured for a particle group having a circle-equivalent diameter of 1 μm or more is obtained from the following equation for n particles, and then obtained by the following equation.
Circularity (Ci) = perimeter of circle equal to projected area of particle / perimeter of projected particle image

In the above formula, fi is the frequency of particles having a circularity Ci.
The average circularity can be measured using a flow type particle image analyzer “FPIA-2100” (trade name) or “FPIA-3000” (trade name) manufactured by Sysmex Corporation.

(6) Polymerized toner In the present invention, the colored resin particles obtained by the above-described method can be used as they are or as a toner for developing a one-component electrostatic image, with an external additive attached thereto.

By attaching or embedding an external additive on the surface of the colored resin particles, the chargeability, fluidity, storage stability, etc. of the toner can be adjusted.
As the external additive, any external additive conventionally used in toners can be used without any limitation, and examples thereof include inorganic particles and organic resin particles. Examples of inorganic particles include silica, aluminum oxide, titanium oxide, zinc oxide, and tin oxide. Examples of organic resin particles include acrylic acid ester polymer particles, methacrylic acid ester polymer particles, and styrene-acrylic acid esters. Examples thereof include copolymer particles and styrene-methacrylic acid copolymer particles. Of these, silica and titanium oxide are preferred, those having the surface of the particles treated with hydrophobic treatment are preferred, and silica particles treated with hydrophobic treatment are particularly preferred.
The amount of the external additive is not particularly limited, but is usually 0.1 to 6 parts by weight with respect to 100 parts by weight of the colored resin particles.

The toner of the present invention can also be used as a two-component toner that carries a carrier on colored resin particles. As the carrier, a carrier conventionally used for toner can be used without any limitation. For example, iron powder, ferrite powder, magnetic powder such as nickel powder, glass beads, etc. Examples thereof include a resin, a styrene / acrylic resin, a silicone resin, and the like that are surface-treated.
In the case of a two-component toner, the concentration of the colored resin particles in the toner is usually 0.1 to 30% by weight, preferably 0.5 to 15% by weight, and more preferably 3 to 10% by weight.

FIG. 1 shows an example of the configuration of an image forming apparatus to which an electrostatic charge image developing toner provided by the present invention is applied. 1, the electrophotographic apparatus shown in FIG. 1 has a photosensitive drum 1 as a photosensitive member, and the photosensitive drum 1 is mounted so as to be rotatable in the direction of arrow A. The photoconductive drum 1 is provided with a photoconductive layer on a conductive support drum, and this photoconductive layer is, for example, an organic photoconductor, a selenium photoconductor, a zinc oxide photoconductor, an amorphous silicon photoconductor, or the like. Composed. Among these, those composed of organic photoreceptors are preferable. The photoconductive layer is bound to a conductive support drum. Examples of the resin used for binding the photoconductive layer to the conductive support drum include polyester resin, acrylic resin, polycarbonate resin, phenol resin, and epoxy resin. Among these, polycarbonate resin is preferable.
Around the photosensitive drum 1, a charging roll 2 as a charging member, a light irradiation device 3 as an exposure device, a developing device 4, a transfer roll 5 and a cleaning blade 6 are arranged along the circumferential direction.
A fixing device 7 is provided on the downstream side of the photosensitive drum 1 in the transport direction. The fixing device 7 includes a heat roll 7a and a support roll 7b.
The conveyance path of the recording material 14 is provided so as to pass between the photosensitive drum 1 and the transfer roll 5 and between the heat roll 7a and the support roll 7b.
The developing device 4 is a developing device used in a one-component contact developing system, and a developing roll 9 and a developing roll blade 10 that scrapes excess toner on the developing roll in a casing 8 in which toner 13 is accommodated. A supply roll 11 and a stirring blade 12 for stirring the toner are provided.

The process of forming an image using the image forming apparatus shown in FIG. 1 includes a charging process, an exposure process, a development process, a transfer process, a cleaning process, and a fixing process as described below.
The charging step is a step of uniformly charging the surface of the photosensitive drum 1 positively or negatively by the charging member. In addition to the charging roll 2 shown in FIG. 1, there are a charging method using a charging member, a contact charging method for charging with a fur brush, a magnetic brush, a blade, etc., and a non-contact charging method using corona discharge. It is also possible to replace it with a contact charging system or a non-contact charging system.

  In the exposure process, the light irradiation device 3 as an exposure device as shown in FIG. 1 irradiates the surface of the photosensitive drum 1 with light corresponding to the image signal, and the uniformly charged surface of the photosensitive drum 1 is irradiated. This is a step of forming an electrostatic latent image. Examples of such a light irradiation device 3 include a laser irradiation device and an LED irradiation device.

  The development process is a process in which a toner is attached to the electrostatic latent image formed on the surface of the photosensitive drum 1 by the exposure process to form a visible image. In the reverse development, a light irradiation unit The toner is attached only to the non-irradiated portion in the regular development.

In the one-component contact developing type developing device 4, the stirring blade 12 is disposed in a toner tank 8 a formed on the upstream side of the casing 8 in the toner supply direction, and stirs the toner 13.
The developing roller 9 is disposed so as to partially contact the photosensitive drum 1 and rotates in the direction B opposite to the photosensitive drum 1. The supply roll 11 comes into contact with the developing roll 9 and rotates in the same direction C as the developing roll 9, receives the supply of toner 13 from the toner tank 8 a by the stirring blade 12, and attaches the toner to the outer periphery of the supply roll 11. The toner is supplied to the outer periphery of the developing roll 9. Other development methods include a one-component non-contact development method, a two-component contact development method, and a two-component non-contact development method.

  Around the developing roll 9, a developing layer blade 10 as a toner layer thickness regulating member and a toner charging member is disposed at a position between the contact point with the supply roll 11 and the contact point with the photosensitive drum 1. ing. The developing roll blade 10 is made of, for example, a conductive rubber elastic body or metal.

The transfer step is a step of transferring a visible image of the surface of the photosensitive drum 1 formed by the developing device 4 to a recording material 14 such as paper, and is usually transferred by a transfer roll 5 as shown in FIG. There are other types of belt transfer and corona transfer.
The cleaning step is a step of cleaning the toner remaining on the surface of the photosensitive drum 1 after the transfer step. In the present invention, the toner remaining on the surface of the photosensitive drum 1 by pressing the cleaning blade 6 on the photosensitive member. Scrape off. The toner scraped off is usually collected by a collecting device (not shown).

  In the image forming apparatus shown in FIG. 1, the surface of the photosensitive drum 1 is uniformly charged negatively by the charging roll 2, and then an electrostatic latent image is formed by the light irradiation device 3. The visible image is developed by 4. Next, the visible image on the photosensitive drum 1 is transferred to a recording material 14 such as paper by the transfer roll 5, and the transfer residual toner remaining on the surface of the photosensitive drum 1 is cleaned by the cleaning blade 6. Thereafter, the next image forming cycle starts.

The fixing step is a step of fixing the visible image of the toner transferred to the recording material 14, and in the image forming apparatus shown in FIG. 1, at least one of a heat roll 7a and a support roll 7b heated by a heating means (not shown). One of them is rotated and heated and pressurized while passing the recording material 14 between them.
As the fixing method, heating, pressure, heating pressure, solvent vapor, and the like are known, and among them, the heating pressure method using a heat roller as described above is most widely used.

  The image forming apparatus shown in FIG. 1 is for monochrome use, but the image forming method of the present invention can also be applied to a color image forming apparatus such as a copying machine or a printer that forms a color image.

  The toner of the present invention as described above is used to develop a latent image having electrostatic characteristics of an electrostatic latent image by electrophotography, electrostatic recording method, electrostatic printing method, etc. It is widely used in an electrostatic latent image developing system, a developing method, and an image forming apparatus that form images such as.

  The toner for developing an electrostatic charge image of the present invention can be a toner excellent in environmental stability by suppressing variation in chargeability, particularly under conditions of high temperature and high humidity. Therefore, the image density is high and high quality printing can be performed.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited only to these examples. Parts and% are based on weight unless otherwise specified.

[Example 1]
83 parts of styrene, 17 parts of butyl acrylate, 5.0 parts of magenta colorant (trade name “FUJI FAST CARMIN” manufactured by Fuji Color Co., Ltd.) mixed with PR31 and PR150, and aluminum coupling agent (alkyl acetoacetate aluminum diisopropyl Rate: 0.25 part of Ajinomoto Fine Techno Co., Ltd., trade name “Plain Out AL-M”) was added and stirred to prepare a polymerizable monomer mixture. Dispersion treatment was performed with an “OB bead mill” to finely disperse the magenta colorant.

  Next, 105 parts of the polymerizable monomer mixture in which the magenta colorant is finely dispersed is added to 0.5 part of a polymethacrylate macromonomer (manufactured by Toagosei Co., Ltd., trade name “AA6”), dipentaerythritol. 8 parts of hexamyristate, 1.5 parts of t-dodecyl mercaptan as a molecular weight regulator, and 0.5 parts of divinylbenzene as a crosslinkable monomer were added and dissolved by stirring to obtain a polymerizable monomer composition. .

  On the other hand, an aqueous solution in which 8.2 parts of sodium hydroxide was dissolved in 50 parts of ion-exchanged water was gradually added with stirring to an aqueous solution in which 14.7 parts of magnesium chloride was dissolved in 250 parts of ion-exchanged water. A colloidal dispersion was prepared.

  The polymerizable monomer composition is added to the magnesium hydroxide colloidal dispersion obtained above, stirred, and then t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, product) as a polymerization initiator. 5 parts of “Perbutyl O”) was added, and high shear stirring was performed for 10 minutes at a rotational speed of 15,000 rpm using an in-line type emulsifying disperser (trade name “Ebara Milder” manufactured by Ebara Seisakusho). Then, droplets of the polymerizable monomer composition were formed.

  The aqueous dispersion in which droplets of the polymerizable monomer composition were dispersed was put into a reactor equipped with a stirring blade, and the temperature was raised to 90 ° C. to carry out a polymerization reaction. After the polymerization conversion rate reaches almost 100%, the polymerization temperature is kept as it is, 1 part of methyl methacrylate as a polymerizable monomer for shell layer, 1 part of ethyl p-styrenesulfonate represented by the following formula (4) 0.1 part of 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide] (trade name “VA086” manufactured by Wako Pure Chemical Industries, Ltd.) dissolved in 10 parts of ion-exchanged water Was added, and the reaction was continued at 90 ° C. for 3 hours. Then, the reaction was stopped, and an aqueous dispersion of colored resin particles having a core-shell structure was obtained. The pH of the aqueous dispersion was 9.5.

  While stirring the aqueous dispersion of colored resin particles obtained above, sulfuric acid is added to adjust the pH to 6 or less, acid washing is performed, water is separated by filtration, and 500 parts of ion-exchanged water is newly added to re-add. Slurried and washed with water. Thereafter, again, dehydration and water washing were repeated several times, and the solid content was separated by filtration, followed by drying at 40 ° C. for 2 days and nights, with a volume average particle size (Dv) of 6.6 μm, particle size Colored resin particles having a distribution (Dv / Dp) of 1.19 and an average circularity of 0.979 were obtained.

  To 100 parts of the colored resin particles, 0.5 part of silica having a volume average particle diameter of 12 nm and 2.0 parts of silica having a volume average particle diameter of 40 nm are added, and mixed at a rotation speed of 1,400 rpm for 10 minutes using a Henschel mixer. Thus, the toner of Example 1 was obtained.

[Example 2]
A toner of Example 2 was obtained in the same manner as in Example 1 except that 2 parts of ethyl p-styrenesulfonate represented by the above formula (4) was used. The dried colored resin particles of Example 2 had a volume average particle size (Dv) of 6.7 μm, a particle size distribution (Dv / Dp) of 1.20, and an average circularity of 0.980.

Example 3
In Example 1 above, after the polymerization conversion rate of the polymerizable monomer composition reached 50 to 70%, it was carried out except that 2 parts of ethyl p-styrenesulfonate represented by the above formula (4) was added. The toner of Example 3 was obtained in the same manner as in Example 1. The dried colored resin particles of Example 3 had a volume average particle size (Dv) of 6.8 μm, a particle size distribution (Dv / Dp) of 1.19, and an average circularity of 0.979.

Example 4
In Example 1, instead of 1.8 parts of ethyl p-styrenesulfonate represented by the above formula (4) and a magenta colorant mixed with PR31 and PR150, a cyan colorant (Dainippon Ink Co., Ltd., product) The toner of Example 4 was obtained in the same manner as in Example 1 except that 5.0 parts of the name “FASTOGEN BLUE GCTF”) were used. The dried colored resin particles of Example 4 had a volume average particle size (Dv) of 6.4 μm, a particle size distribution (Dv / Dp) of 1.22, and an average circularity of 0.980.

Example 5
A toner of Example 5 was obtained in the same manner as in Example 4 except that 3 parts of ethyl p-styrenesulfonate represented by the above formula (4) was used. In addition, the colored resin particles of Example 5 after drying had a volume average particle diameter (Dv) of 6.6 μm, a particle diameter distribution (Dv / Dp) of 1.20, and an average circularity of 0.980.

Example 6
In Example 1, instead of 0.6 parts of ethyl p-styrenesulfonate represented by the above formula (4) and a magenta colorant obtained by mixing PR31 and PR150, a yellow colorant PY74 (manufactured by Sanyo Dye Co., Ltd., The toner of Example 6 was prepared in the same manner as in Example 1 except that 6 parts of the product name “Fast Yellow 7415”) and 1 part of the yellow colorant PY74 (manufactured by Sanyo Dye Co., Ltd., trade name “Fast Yellow 7416”) were used. Obtained. In addition, the colored resin particles of Example 6 after drying had a volume average particle diameter (Dv) of 6.7 μm, a particle diameter distribution (Dv / Dp) of 1.20, and an average circularity of 0.982.

Example 7
A toner of Example 7 was prepared in the same manner as in Example 6 except that 0.6 part of ethyl p-styrenesulfonate represented by the above formula (4) was changed to 1.2 part in Example 6 above. Got. The dried colored resin particles of Example 7 had a volume average particle size (Dv) of 6.7 μm, a particle size distribution (Dv / Dp) of 1.19, and an average circularity of 0.980.

[Comparative Example 1]
In Example 1, the negative charge control resin (manufactured by Fujikura Kasei Co., Ltd., trade name “No” is added when preparing a polymerizable monomer composition without adding ethyl p-styrenesulfonate represented by the above formula (4). A toner of Comparative Example 1 was obtained in the same manner as Example 1 except that 5 parts of FCA626N ", sulfonic acid, 7% functional group product) was added. The dried colored resin particles of Comparative Example 1 had a volume average particle size (Dv) of 7.2 μm, a particle size distribution (Dv / Dp) of 1.26, and an average circularity of 0.968.

[Comparative Example 2]
A toner of Comparative Example 2 was obtained in the same manner as in Example 1 except that ethyl p-styrenesulfonate was not added. In addition, the colored resin particles of Comparative Example 2 after drying had a volume average particle size (Dv) of 6.3 μm, a particle size distribution (Dv / Dp) of 1.19, and an average circularity of 0.967.

[Comparative Example 3]
Comparative Example 4 was prepared in the same manner as in Example 1 except that 2 parts of p-styrenesulfonic acid represented by the following formula (5) was used instead of ethyl p-styrenesulfonate in Example 1 above. No toner was obtained. In addition, the colored resin particles of Comparative Example 3 after drying had a volume average particle size (Dv) of 6.9 μm, a particle size distribution (Dv / Dp) of 1.21, and an average circularity of 0.979.

[Comparative Example 4]
In the comparative example 3, in place of 3 parts of p-styrenesulfonic acid represented by the above formula (5) and a magenta colorant in which PR31 and PR150 are mixed, a cyan colorant (trade name “FASTOGEN, manufactured by Dainippon Ink and Chemicals, Inc.) BLUE GCTF ") was used in the same manner as Comparative Example 3 except that 5.0 parts was used, and a toner of Comparative Example 4 was obtained. The dried colored resin particles of Comparative Example 4 had a volume average particle diameter (Dv) of 7.0 μm, a particle diameter distribution (Dv / Dp) of 1.21, and an average circularity of 0.980.

[Comparative Example 5]
In the comparative example 3, instead of 1.2 parts of p-styrenesulfonic acid represented by the above formula (5) and a magenta colorant obtained by mixing PR31 and PR150, a yellow colorant PY74 (manufactured by Sanyo Dye Co., Ltd., product) The toner of Comparative Example 5 was prepared in the same manner as in Example 1 except that 5 parts of the name “Fast Yellow 7415”) and 1 part of the yellow colorant PY74 (manufactured by Sanyo Dye, trade name “Fast Yellow 7416”) were used. It was. The dried colored resin particles of Comparative Example 4 had a volume average particle size (Dv) of 6.8 μm, a particle size distribution (Dv / Dp) of 1.23, and an average circularity of 0.976.

The test methods performed in this example are as follows.
The LL environment represents a temperature of 10 ° C. and a humidity of 20%, the NN environment represents a temperature of 23 ° C. and a humidity of 50%, and the HH environment represents a temperature of 32 ° C. and a humidity of 80%.

(1) Measurement of adsorbed moisture amount IGAsorb Moisture Sorption Analyzer (trade name, manufactured by HIDEN ANALYTICAL) was used to measure the adsorbed moisture amount of the toner. The specific measurement method is as follows.
Prior to measuring the amount of adsorbed water, the temperature was set to 32 ° C., the inside of the chamber was dried with a nitrogen flow at a flow rate of 400 to 500 ml / min for 3 hours or more, and the inside of the measuring cell was dried to some extent. A dedicated sample jig was set, and 30 to 40 mg of toner was precisely weighed with an internal balance. Thereafter, the chamber was closed, and the inside of the chamber was dried again by nitrogen flow at a flow rate of 400 to 500 ml / min until the humidity became 0.7 RH% or less.
After the drying, the flow rate of nitrogen flow is set to 250 ml / min, and the toner weight average value for 10 minutes immediately before a certain time is set as the reference weight. It was confirmed that the toner weight fluctuation rate was stable within ± 0.3% for 10 minutes with respect to this reference weight, and the toner weight at this time was defined as W1. Thereafter, the temperature is not changed, the humidity is increased to 80%, and the toner weight when the measured expected value by the polynomial approximation of the actual measurement value and the actual measurement value is stabilized with an accuracy within 98% after the start of measurement is kept for at least 10 minutes. Was W2. In addition, the value of the adsorbed water amount in the measurement condition environment of the sample jig itself, which was confirmed in advance, was set to W3. From these values, the amount of toner adsorbed water was determined by the following equation.
Adsorption moisture amount (% by weight) = 100 × (W2−W1−W3) / W1

The weight fluctuation rate is the average value of the toner weight measured periodically within a certain period of time after drying in an environment where the temperature is 32 ° C. and the relative humidity is 0.7% or less. After the measurement, the amount of fluctuation of the changed toner weight is expressed as a percentage, and is expressed by the following calculation formula.
<Calculation formula>
Weight fluctuation rate (%) = 100 × (reference weight−toner weight after change) / reference weight

(2) Measurement of particle diameter The volume average particle diameter (Dv) and the number average particle diameter (Dp) were measured by a particle diameter measuring machine (Beckman Coulter, model name “Multisizer”). The measurement with this multisizer was performed under the conditions of aperture diameter: 100 μm, medium: Isoton II, and number of measured particles: 100,000.
Specifically, 0.1 g of toner was placed in a beaker, and 0.1 mL of an alkylbenzene sulfonic acid aqueous solution (manufactured by Fuji Film, trade name “Dry Well”) was further added as a dispersant. 10-30 mL of Isoton II was further added to the beaker, and the mixture was dispersed for 1 to 3 minutes with an ultrasonic disperser, and then measured with the particle size measuring instrument.

(3) Average circularity of toner 10 ml of ion-exchanged water is placed in a container in advance, 0.02 g of a surfactant (alkylbenzenesulfonic acid) is added as a dispersant, 0.02 g of toner is further added, and ultrasonic waves are added. Dispersion treatment was performed with a disperser at 60 W for 3 minutes. An appropriate amount of ion-exchanged water is added to adjust the toner density at the time of measurement to 3,000 to 10,000 particles / μL, and 1,000 to 10,000 colored resin particles having an equivalent circle diameter of 1 μm or more are prepared by Sysmex. It measured using the flow type | formula particle image analyzer (brand name "FPIA-2100") by a company.

(4) Thickness of shell layer The thickness of the shell layer is determined by the volume average particle diameter (Dv) of the colored resin particles measured by the particle diameter measuring apparatus of (2) above and the polymerizability for the core used in the toner preparation step. From the addition amount of monomer (styrene, n-butyl acrylate, divinylbenzene, macromonomer) and the addition amount of polymerizable monomer for shell layer (methyl methacrylate, styrene sulfonate compound, styrene sulfonic acid), respectively It was calculated by the following formula. The specific gravity of the core polymerizable monomer and the shell layer polymerizable monomer was assumed to be the same.

(5) Measurement of toner charge amount Q / M on the surface of the developing roll Set printing paper in a commercially available one-component developing type printer (18-sheet printer), put toner in the developing device, and in an LL or NN environment After being left for a whole day and night, printing was performed in an LL or NN environment for evaluation.
First, white solid printing is performed, and then the second white solid printing is stopped halfway, and then the toner charge amount Q / M (μC / g) adhering to the developing roll is determined by a suction-type charge amount measuring device ( Measured using a product name “210HS-2A” manufactured by Trek Japan.

(6) Environmental initial printing test Printing paper was set in the printer used in the above (5), toner was put in the developing device, and left for one day in an HH environment, and then fog was measured as follows.
White solid print (0% print density) is performed, and the printer is stopped at about 10 prints on the way, and the toner remaining on the non-image area on the photoconductor after development is adhesive tape (manufactured by Sumitomo 3M Limited). , Trade name "Scotch Mending Tape 810-3-18"). This adhesive tape was affixed to a new printing paper, and the color tone was measured with a spectral color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name “SE-2000”). As a reference (reference sample), an unused adhesive tape was affixed to printing paper, and the color tone was measured in the same manner. Each color tone is expressed as coordinates in the L * a * b * space, and a color difference ΔE is calculated from the color tone of the measurement sample and the reference sample to obtain a fog value. The smaller this value is, the smaller the fog is. If the fog value ΔE is 1.0 or less, the image quality is good.

〔result〕
The test results are shown in Tables 1 and 2.
The notes in Tables 1 and 2 are as follows.
* 1: Abbreviations for binder resin and polymerizable monomer for shell ST (styrene), BA (butyl acrylate) DVB (divinylbenzene), MMA (methyl methacrylate)
* 2 Abbreviations for colorants: CARMIN (magenta colorant, manufactured by Fuji Color Co., Ltd., trade name “FUJI FAST CARMIN”), GCTF (cyan colorant, manufactured by Dainippon Ink, Inc., trade name “FASTOGEN BLUE GTCF”), FAST 7415 (yellow) Colorant, Sanyo Color Co., Ltd., trade name “Fast Yellow 7415”) FAST7416 (Yellow Colorant, Sanyo Color Co., Ltd., trade name “Fast Yellow 7416”)
* 3: Abbreviation for charge control resin 626N (negative charge control resin, manufactured by Fujikura Kasei, trade name “FCA626N”, sulfonic acid functional group 7% product)

[Summary of results]
The toners of Examples 1 to 7 coated with a shell layer containing a repeating unit derived from the styrene sulfonic acid ester compound of the present invention have excellent environmental stability with no fogging even in a high temperature and high humidity environment. Met.
On the other hand, the toner of Comparative Example 1 using a conventional charge control resin showed a decrease in environmental stability, as can be seen from the fact that the amount of adsorbed water under high temperature and high humidity after toner production was high. . In addition, the toner of Comparative Example 2 prepared without adding a charge control agent containing a polar functional group imparting chargeability or the styrene sulfonate compound according to the present invention is adsorbed in a high temperature and high humidity environment. Although the amount of water was within the range defined by the present invention, fog was observed because the chargeability of the toner was insufficient (particularly in NN and LL environments).
Further, in the toners of Comparative Examples 3 to 5 containing styrene sulfonic acid as a binder resin monomer, it was confirmed that the environmental stability in a high temperature and high humidity environment was lowered due to the hydrophilicity caused by styrene sulfonic acid.

1 is a diagram illustrating a configuration example of an electrophotographic apparatus that performs an image forming method according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roll 3 Light irradiation apparatus 4 Developing apparatus 5 Transfer roll 6 Cleaning blade 7 Fixing apparatus 7a Heat roll 7b Support roll 8 Casing 8a Toner tank 9 Developing roll 10 Developing roll blade 11 Supply roll 12 Stirring blade 13 Toner 14 Recording material

Claims (10)

In a method for producing a toner for developing an electrostatic charge image, comprising colored resin particles having a core-shell structure in which core particles containing a first binder resin and a colorant are coated with a shell layer containing a second binder resin. ,
Dispersing the liquid containing the core polymerizable monomer in the aqueous dispersion medium to form droplets containing the core polymerizable monomer, step A, polymerizing the liquid droplets in the aqueous dispersion medium Then, a polymerizable monomer for the shell layer containing the styrene sulfonate compound represented by formula (1) is added to the step B of forming the core particles and the aqueous dispersion medium in which the core particles are dispersed. And a process C for polymerizing to form a shell layer.

(Wherein R ¹ and R ² each independently represent a substituent selected from a hydrogen atom, an alkyl group, or an alkenyl group. R ³ represents an alkyl group or an alkenyl group.)   The amount of the styrene sulfonate compound represented by the formula (1) is 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the monovinyl monomer in the core polymerizable monomer. The method for producing a toner for developing an electrostatic image according to claim 1.   3. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein, in the step A, the droplet contains the polymerizable monomer for the core and a colorant. In the electrostatic charge image developing toner comprising colored resin particles having a core-shell structure in which core particles containing a first binder resin and a colorant are coated with a shell layer containing a second binder resin.
The toner for developing an electrostatic charge image, wherein the second binder resin contains a copolymer containing a repeating unit derived from a styrene sulfonate compound represented by the following formula (1).

(Wherein R ¹ and R ² each independently represent a substituent selected from a hydrogen atom, an alkyl group, or an alkenyl group. R ³ represents an alkyl group or an alkenyl group.)   The colored resin particles include a step A in which a liquid containing the core polymerizable monomer is dispersed in an aqueous dispersion medium to form droplets containing the core polymerizable monomer; Step B for polymerizing in an aqueous dispersion medium to form core particles, and polymerization for a shell layer containing the styrene sulfonate compound represented by formula (1) in the aqueous dispersion medium in which the core particles are dispersed The toner for developing an electrostatic charge image according to claim 4, wherein the toner is produced by a method including a step C of forming a shell layer by adding a polymerizable monomer for polymerization.   The amount of the styrene sulfonate compound represented by the formula (1) is 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the monovinyl monomer in the core polymerizable monomer. 6. The toner for developing an electrostatic charge image according to claim 4, wherein the toner is for developing an electrostatic image.   7. The electrostatic charge image developing toner according to claim 5, wherein in the step A, the liquid droplets contain the core polymerizable monomer and a colorant.   8. The electrostatic image developing toner according to claim 4, wherein the amount of adsorbed water at a temperature of 32 ° C. and a relative humidity of 80% is 0.05 to 0.3% by weight.   The toner for developing an electrostatic charge image according to any one of claims 4 to 8, wherein the thickness of the shell layer is 5 to 1000 nm.   10. The electrostatic image developing toner according to claim 4, wherein the core particle does not contain a charge control agent.

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