JP2017021306A - Charge control agent-containing particle and manufacturing method of the same - Google Patents

Abstract

SOLUTION: Charge control agent-containing particles of the present invention each comprise: a core part formed of a polymer that includes 51 to 99.5 weight% of a structural unit derived from a monofunctional vinyl monomer and 0.5 to 49 weight% of a structural unit derived from a polyfunctional vinyl monomer, and is at least partially cross linked; and a shell part formed of a vinyl polymer that contains a charge control agent.EFFECT: Charge control agent-containing particles according to the present invention have sufficiently developed effect as a charge control agent, are excellent in chargeability, and can be suitably used particularly as a toner. The charge control agent-containing particles of the present invention preferably do not contain a surfactant, and thereby can further develop an effect of improving chargeability with the charge control agent.SELECTED DRAWING: None

Description

  The present invention relates to particles containing a charge control agent and a method for producing the same. More specifically, the present invention relates to polymer particles suitable for toner use and the like, in which the chargeability is controlled by including a charge control agent, and a method for producing the same.

  Toner, which is an electrophotographic powder developer, is widely used as an electrophotographic developer for copying and the like. In printing using electrophotographic technology, an image is usually formed by attaching electrostatically charged toner, which is charged colored fine particles, and the formed powder image is transferred onto paper, then fixed by heating and pressing. To get a print. For this reason, the toner is required to have appropriate chargeability.

  In a two-component developer in which a toner and a carrier are mixed, the toner is charged by contact and friction between the toner and the carrier. Among the materials constituting the toner, the charge control agent is a charge polarity of the toner. This has a particularly large effect on the charge amount.

  Currently, the toner includes a pulverized toner obtained by pulverizing a resin mixed with materials such as resin, pigment, charge control agent and wax, and a polymerized toner obtained by producing a polymer as a droplet in a liquid ( Chemical toners are known, and among them, polymerized toners are easily obtained as spherical particles, and thus are widely used as those having excellent fluidity and the like than pulverized toners that are indefinite. Further, among the polymerized toners, a polymerized toner formed through an aggregation / association process (granulation process) in which fine particles are aggregated to grow into toner particles has attracted attention. (See Non-Patent Document 1)

  However, in these toners, most of the charge control agent is buried inside the toner. Since it is considered that the substance on the toner surface particularly affects the charging of the toner, the state in which the charge control agent is buried is not a preferable state. It has been studied to stir and mix with a mixer after toner production so that the charge control agent is localized on the toner surface, and to embed the charge control agent in the toner surface. However, there is a problem that complicates the process.

Patent Search Guidebook “Polymerized Toner” published by the Japan Patent Office in March 2008 (http://www.jpo.go.jp/shiryou/s_sonota/pdf/pat_guidebook/h19_02.pdf)

  The present invention solves the above-mentioned problems, the charge control agent is localized on the surface, the chargeability is effectively controlled even when the amount of the charge control agent added is small, and suitable for toner applications. It is an object to provide contained particles and a method for producing the same.

The present invention relates to the following items [1] to [7].
[1] 51 to 99.5% by weight of structural units derived from a monofunctional vinyl monomer, 0.5 to 49% by weight of structural units derived from a polyfunctional vinyl monomer, and at least a part of A core made of a crosslinked polymer;
A charge control agent-containing particle having a shell portion made of a vinyl polymer containing a charge control agent.
[2] The charge control agent-containing particles according to [1], which are substantially free of an emulsifier and a surfactant.
[3] The charge control agent-containing particles according to [1] or [2], wherein the core part is obtained by soap-free emulsion polymerization.
[4] Monomer component polymerization using 51 to 99.5% by weight of monofunctional vinyl monomer and 0.5 to 49% by weight of polyfunctional vinyl monomer. And a first step of carrying out crosslinking to produce core particles,
Charge control agent-containing particles comprising: a second step of polymerizing a vinyl monomer in the presence of a charge control agent and forming a shell made of a polymer containing the charge control agent on the core particle. Manufacturing method.
[5] The method for producing charge control agent-containing particles according to [4], wherein the vinyl monomer used in the second step is a monofunctional vinyl monomer.
[6] The method for producing charge control agent-containing particles according to [4] or [5], wherein the charge control agent is dissolved in a vinyl monomer and used in the second step.
[7] The method for producing a charge control agent-containing particle according to any one of [4] to [6], wherein the polymerization in the first step is performed by soap-free emulsion polymerization.

  The charge control agent-containing particles of the present invention sufficiently exhibit the effect of the charge control agent, have excellent chargeability, and can be suitably used particularly for toner applications. In addition, the charge control agent-containing particles of the present invention preferably do not contain an emulsifier and a surfactant, and can thereby exhibit the effect of improving the chargeability by the charge control agent.

  According to the method for producing charge control agent-containing particles of the present invention, there is provided a method for producing charge control agent-containing particles that exhibit the effect of the charge control agent sufficiently, have excellent chargeability, and are suitably used particularly for toner applications. can do.

Hereinafter, the present invention will be specifically described.
In the present specification, “(meth) acryl” means acryl or methacryl, “(meth) acrylate” means acrylate or methacrylate, and “(meth) acryloyl” means acryloyl or methacryloyl. .

Charge Control Agent-Containing Particles The charge control agent-containing particles according to the present invention have a core part and a shell part.
<Core part>
The core part of the charge control agent-containing particles of the present invention has 51 to 99.5% by weight of structural units derived from a monofunctional vinyl monomer and 0.5 to 0.5% of structural units derived from a polyfunctional vinyl monomer. It is composed of a polymer containing ˜49% by weight and at least partially crosslinked.

  Here, the content ratio of the structural unit derived from the monofunctional vinyl-based monomer and the structural unit derived from the polyfunctional vinyl-based monomer is a ratio in the entire core portion, and this range is within the core portion. There is no problem even if an unsatisfied polymer is localized or unevenly distributed. Further, as for the crosslinked part of the polymer, it is sufficient that the polymer at least partially crosslinked is present in the core part, and the crosslinked part may be localized or unevenly distributed in the core part.

  In a polymer in which at least a part of the core part is cross-linked (hereinafter also simply referred to as a cross-linked polymer), a structural unit derived from a monofunctional vinyl monomer and a polyfunctional vinyl monomer are used. The ratio with the structural unit is usually the same as the ratio of the charged amount of the monomer component when the polymer is produced.

  That is, the core part of the charge control agent-containing particles of the present invention comprises 51 to 99.5 parts by weight of a monofunctional vinyl monomer and 0.5 to 49 parts by weight of a polyfunctional vinyl monomer. It is obtained by polymerizing using as a body component and at least partially crosslinking. Crosslinking may be performed simultaneously with the polymerization, or may be performed subsequent to the polymerization.

As the monofunctional vinyl monomer, any compound having one vinyl bond (ethylenically unsaturated group) in the molecule can be used.
Examples of monofunctional vinyl monomers include (meth) acrylic monomers, styrene monomers, acrylonitrile monomers, and olefin monomers.

Specific examples of acrylic monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (meth ) Hexyl acrylate, (meth) acrylic acid-2-ethylhexyl, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, (Meth) acrylic acid alkyl esters such as stearyl (meth) acrylate;
(Meth) acrylic acid cyclic esters such as (meth) acrylic acid cyclohexyl, (meth) acrylic acid isobornyl, (meth) acrylic acid phenyl, (meth) acrylic acid benzyl, (meth) acrylic acid phenoxyethyl;
(Meth) acrylic acid alkoxyalkyl esters such as (meth) acrylic acid methoxyethyl, (meth) acrylic acid ethoxyethyl, (meth) acrylic acid propoxyethyl, (meth) acrylic acid butoxyethyl and (meth) acrylic acid ethoxypropyl ;
(Meth) acrylic acid, (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-4-hydroxybutyl, (meth) acrylic acid amide, (meth) acrylic acid glycidyl, (meth) acrylic acid-4- Examples include functional group-containing acrylic monomers such as glycidyloxybutyl. The alkyl group of the (meth) acrylic acid alkyl ester may be linear or branched.

Specific examples of styrenic monomers include alkyls such as styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene and octyl styrene. Styrenes;
Halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, chloromethylstyrene and iodinated styrene;
Nitrostyrene; acetylstyrene; methoxystyrene; α-methylstyrene and the like.

Specific examples of the acrylonitrile monomer include acrylonitrile, methacrylonitrile, and derivatives thereof.
Examples of olefin monomers include α-olefins and cyclic olefins. Specific examples of α-olefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1 -Octene, 4-methyl-1-pentene, etc. are mentioned, and norbornene, norbornene derivatives, etc. are mentioned as cyclic olefin.

  Other monofunctional vinyl monomers include vinyl esters such as vinyl acetate and vinyl propionate, unsaturated carboxylic acids such as itaconic acid, crotonic acid and maleic acid, and esters thereof, and vinyl chloride. .

  These monofunctional vinyl monomers used in the present invention may be used singly or in combination of two or more. In the present invention, the monofunctional vinyl monomer preferably contains an acrylic monomer.

As the polyfunctional vinyl monomer, a compound having two or more vinyl bonds (ethylenically unsaturated groups) in the molecule can be used.
Examples of the polyfunctional vinyl monomer include polyfunctional (meth) acrylic monomers, divinyl compounds, triene compounds, diallyl compounds, triallyl compounds, and tetraallyl compounds.

  As the polyfunctional (meth) acrylic monomer, those known as polyfunctional (meth) acrylic acid having two or more ethylenically unsaturated groups in one molecule can be used without particular limitation, and modified. Bifunctional or higher (meth) acrylic acid which may be present, preferably 2 to 6 functional (meth) acrylic acid which may be modified. Here, examples of the modification include ethylene oxide (EO) modification, propylene oxide (PO) modification, and the like.

  Specific examples of the polyfunctional (meth) acrylic monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Propoxylated ethoxylated bisphenol A di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, propoxylated bisphenol A di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, 1,10-decanediol di (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) Acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethoxylated polypropylene glycol di (meth) acrylate, glycerin di (meth) acrylate, ethoxylated isocyanuric acid Tri (meth) acrylate, ε-caprolactone modified tris- (2-acryloxyethyl) isocyanurate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, Ditrimethylolpropane tetra (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, pentaerythritol tetra ( Data) acrylate, dipentaerythritol poly (meth) acrylate and dipentaerythritol hexa (meth) acrylate.

Specific examples of the divinyl compound include divinylbenzene and divinyl adipate.
Specific examples of diallyl compounds and triallyl compounds include diallyl phthalate, triallyl isocyanurate, and tetraallyloxyethane.

  These polyfunctional vinyl monomers may be used alone or in combination of two or more. In the present invention, the polyfunctional vinyl monomer preferably contains a polyfunctional (meth) acrylic monomer.

  The cross-linked polymer forming the core part is 51 to 99.5% by weight of structural units derived from a monofunctional vinyl monomer, and 0.5 to 49% by weight of structural units derived from a polyfunctional vinyl monomer. %, Preferably 90 to 99.5% by weight of structural units derived from monofunctional vinyl monomers, 0.5 to 10% by weight of structural units derived from polyfunctional vinyl monomers, more preferably Contains 95 to 99% by weight of structural units derived from a monofunctional vinyl monomer and 1 to 5% by weight of structural units derived from a polyfunctional vinyl monomer.

  In the present invention, the cross-linked polymer forming the core portion is composed of 51 to 99.5% by weight of structural units derived from monofunctional vinyl monomers as a whole, and structural units derived from polyfunctional vinyl monomers. In the core part, each structural unit may be unevenly distributed, or may be present homogeneously.

The core part of the charge control agent-containing particles of the present invention includes a particulate cross-linked polymer obtained by copolymerizing a monofunctional vinyl monomer and a polyfunctional vinyl monomer and cross-linking at least a part thereof. The coalescence is preferably used as it is. The polymerization process for obtaining the crosslinked polymer may be one-stage or multi-stage, and the crosslinking may be performed simultaneously with the polymerization or after the polymerization. The particulate crosslinked polymer serving as the core portion may be homogeneous as a whole, or may be heterogeneous between the central portion and the outer peripheral portion. For example, in the case of producing a crosslinked polymer through polymerization in multiple stages, the core part is subjected to a process in which a monofunctional vinyl monomer is polymerized in the first stage and a polyfunctional vinyl monomer is polymerized in the second and subsequent stages. May be formed. The core part thus obtained has a structure in which there are many structural units derived from a monofunctional vinyl monomer at the center and many structural units derived from a polyfunctional vinyl monomer at the outer periphery. As a result, the outer peripheral portion has a large number of bridging portions. It is preferable that the outer peripheral portion of the core portion has a large number of cross-linked portions because the charge control agent contained in the shell portion is difficult to move to the core portion.
Such a crosslinked polymer is preferably obtained by a production method described later.

  The core part of the charge control agent-containing particles of the present invention is a particle composed of the above-mentioned crosslinked polymer, and preferably does not contain a surfactant and an emulsifier. Such a core part is preferably obtained by soap-free emulsion polymerization.

Moreover, since the charge control agent-containing particles of the present invention need only have the charge control agent unevenly distributed in the shell part, it is not necessary to contain the core part charge control agent.
The particle size of the core is not particularly limited, but when the charge control agent-containing particles are used for toner, it is usually 50 to 800 nm, preferably about 100 to 400 nm.

<Shell part>
The shell part of the charge control agent-containing particles of the present invention is made of a vinyl polymer containing a charge control agent.
The vinyl polymer containing the charge control agent that forms the shell part may be obtained by polymerizing or copolymerizing monomer components in the presence of the charge control agent. May be obtained by blending a vinyl polymer with a charge control agent. Among these, since the charge control agent is homogeneously dispersed in the vinyl polymer, the charge control agent is preferably obtained by polymerizing or copolymerizing the monomer component in the presence of the charge control agent. More preferably, the monomer component in which the control agent is dissolved is obtained by polymerization or copolymerization.

As the vinyl polymer, a polymer or copolymer of one or more kinds of vinyl monomers can be used, and the vinyl monomer is preferably a monofunctional vinyl monomer. .
As the monofunctional vinyl monomer, any compound having one vinyl bond (ethylenically unsaturated group) in the molecule can be used. For example, a (meth) acrylic monomer, a styrene monomer Examples include a monomer, an acrylonitrile monomer, and an olefin monomer. Specifically as these monofunctional vinyl monomers, those exemplified as the monofunctional vinyl monomers used in the production of the above-mentioned crosslinked polymer forming the core can be used. Among these, (meth) acrylic monomers and styrene monomers can be preferably used. The vinyl polymer forming the shell part may be obtained by polymerizing a single monofunctional vinyl monomer alone, or may be obtained by copolymerizing two or more kinds in combination. There may be.

  As the charge control agent, a known charge control agent can be used without particular limitation, and a charge control agent that can impart appropriate chargeability to the resulting particles can be suitably used. As the charge control agent, any conventionally known charge control agent (charge control agent) that can be added to the resin particles for the polymerized toner can be suitably used, and particularly preferably used for the production of a vinyl polymer. It is possible to use a charge control agent that dissolves or uniformly disperses in the vinyl monomer.

Specific examples include benzylic acid compounds, azine compounds, quaternary ammonium salts, azo metal-containing compounds, salicylic acid compounds, and the like.
In the shell portion, the content ratio of the charge control agent to the vinyl polymer is not particularly limited, and depends on the types of the vinyl polymer and the charge control agent, but with respect to 100 parts by weight of the vinyl polymer. The content of the charge control agent is usually in the range of 0.01 to 3 parts by weight, preferably 0.05 to 1 part by weight, more preferably 0.05 to 0.3 parts by weight.

The shell part of the charge control agent-containing particles of the present invention preferably does not contain a surfactant and an emulsifier. Such a shell part is preferably obtained by seed polymerization.
In the charge control agent-containing particles of the present invention, the shell part covers at least a part of the core part, and preferably covers the entire core part.
The thickness of the shell portion is not particularly limited.

<Charge control agent-containing particles>
The charge control agent-containing particles of the present invention have a core part made of a crosslinked polymer and a shell part made of a vinyl polymer containing the charge control agent. The average particle diameter of the charge control agent-containing particles can be determined by calculating from the result of measuring a plurality of charge control agent-containing particles using a scanning electron microscope (SEM). Detailed measurement methods are described in the examples. The average particle diameter of the charge control agent-containing particles is 50 to 1000 nm, preferably 100 to 500 nm.

  Since the charge control agent-containing particles of the present invention have a shell portion made of a vinyl polymer containing a charge control agent, the charge control agent is unevenly distributed on the particle surface, and the effect of the charge control agent can be sufficiently obtained. In the charge control agent-containing particles of the present invention, the core part is made of a polymer that is at least partially cross-linked, so that the core part is stronger than the case that the core part is made of a non-crosslinked polymer and is contained in the shell part. It is considered that the charge control agent is not easily transferred to the core portion, so that the charge control agent remains in the shell portion and the effect of the charge control agent is sufficiently exhibited.

  The charge control agent-containing particles of the present invention are not particularly limited. For example, the charge amount measured using a blow-off charge measuring device as described later is preferably 930 μC / g or more, more preferably 1000 μC / g. It can be in the range of g.

  The charge control agent-containing particles of the present invention are not particularly limited, but the content of the charge control agent in the entire particles is usually 0.005 to 3 parts by weight, preferably about 0.05 to 1% by weight, and more. Preferably, it is about 0.05 to 0.3% by weight. In the charge control agent-containing particles of the present invention, since the charge control agent is unevenly distributed in the shell portion of the particles, it is sufficient even when the content of the charge control agent in the entire particle is relatively small, 0.5% by weight or less. A sufficient amount of charge can be achieved.

Further, the charge control agent-containing particles of the present invention can be substantially free of emulsifiers and surfactants in both the core part and the shell part. That is, the charge control agent-containing particles as a whole can be substantially free of an emulsifier and a surfactant. In this case, the charge control agent-containing particles of the present invention are not affected by the emulsifier and the surfactant, and the effects of the charge control agent are not offset, and the theoretical effect of the charge control agent is preferably exhibited. Is preferable. Note that substantially no emulsifier and surfactant means that the total amount of the monofunctional vinyl monomer and the polyfunctional vinyl monomer constituting the charge control agent-containing particles is 100 parts by weight. This means that the total amount of emulsifier and surfactant is 0.1 parts by weight or less, preferably not intentionally added.
Such charge control agent-containing particles of the present invention can be suitably produced by the method for producing charge control agent-containing particles of the present invention.

Method for Producing Charge Control Agent-Containing Particles The charge control agent-containing particles of the present invention have a first step of producing core particles (core portion) and a second step of forming a shell (shell portion) on the core particles. .
<First step>
In the first step in the method for producing the charge control agent-containing particles of the present invention, the proportion of monofunctional vinyl monomer is 51 to 99.5 wt% and the polyfunctional vinyl monomer is 0.5 to 49 wt%. The monomer component is used to polymerize and crosslink the monomer component to produce core particles.

Monomer component Monofunctional vinyl monomer and polyfunctional vinyl monomer used as the monomer component include the monomers exemplified in the description of the core part of the charge control agent-containing particle. It is done.

  The proportion of the monofunctional vinyl monomer and the polyfunctional vinyl monomer used as the monomer component is usually 51 to 99.5% by weight of the monofunctional vinyl monomer, and the polyfunctional vinyl monomer. Is a proportion of 0.5 to 49% by weight, preferably 90 to 99.5% by weight of the monofunctional vinyl monomer and 0.5 to 10% by weight of the polyfunctional vinyl monomer. Yes, and more preferably, the proportion of the monofunctional vinyl monomer is 95 to 99% by weight and the polyfunctional vinyl monomer is 1 to 5% by weight. The total use ratio of the monofunctional vinyl monomer and the polyfunctional vinyl monomer is usually 100% by weight.

  The use ratio of the monofunctional vinyl monomer and the polyfunctional vinyl monomer of the monomer component is the use ratio in the entire first process, and when performing polymerization in the first process in multiple stages, In the polymerization stage, the above-mentioned use ratio may not be satisfied.

-Polymerization method The polymerization or copolymerization of the monomer component is not particularly limited, but can be carried out by any of polymerization methods of soap-free emulsion polymerization, emulsion polymerization, suspension polymerization, and seed polymerization. By carrying out polymerization by these methods, the core particles (core part) can be made into spherical particles having a uniform particle diameter. These polymerizations are preferably carried out using an aqueous medium, although depending on the type of monomer. Among these, emulsion polymerization or soap-free emulsion polymerization is more preferable, and soap-free emulsion polymerization is particularly preferable.

  When core particles are prepared by soap-free emulsion polymerization, a polymerization initiator is usually used and the suspension containing the core particles is polymerized in an aqueous medium in a system that does not contain a surfactant and an emulsifier. Obtain a liquid. As the polymerization initiator and the aqueous medium, those described later can be used.

  When preparing the core particles by emulsion polymerization, usually, an emulsifier and a polymerization initiator are used, and polymerization is performed in an aqueous medium to obtain a suspension containing the core particles. Examples of the emulsifier used include alkyl benzene sulfonates such as sodium dodecylbenzene sulfonate, polyethylene glycol alkyl ethers such as polyethylene glycol nonyl phenyl ether, and the like. The emulsifier can be used in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the monomer component, preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, Particularly preferred is 0.1 parts by weight or less.

  In the present invention, when the core particles are prepared by soap-free emulsion polymerization, the resulting core particles do not contain a surfactant and an emulsifier, and the inclusion of impurities can be suppressed, and the effect of the charge control agent It is particularly preferable because it does not adversely affect

-Aqueous medium It is preferable to superpose | polymerize the monomer component in a 1st process in an aqueous medium. Examples of the aqueous medium include water or a mixture obtained by adding a hydrophilic organic solvent to water. Examples of water include purified water (ion exchange water, distilled water, etc.), ground water, tap water and the like. Examples of hydrophilic organic solvents include: lower alcohols such as methanol, ethanol and isopropanol; polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol and triethylene glycol; cellosolves such as methyl cellosolve and ethyl cellosolve: acetone Ketones such as; ethers such as tetrahydrofuran; esters such as methyl formate. These hydrophilic organic solvents can be used alone or in combination of two or more. The addition amount of the hydrophilic organic solvent is preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of water.

-Polymerization initiator A polymerization initiator can be used suitably for superposition | polymerization of the monomer component in a 1st process. When the monomer component contains a (meth) acrylic monomer, a known polymerization initiator as a polymerization initiator for the (meth) acrylic monomer is used as the polymerization initiator without any particular limitation. Any of a cationic polymerization initiator and an anionic polymerization initiator can be preferably used.

  Specific examples of the polymerization initiator suitably used in the present invention include persulfates such as ammonium persulfate, potassium persulfate, and sodium persulfate, benzoyl peroxide, acetyl peroxide, methyl ethyl ketone peroxide, and t-butyl peroxide. Organic peroxides such as oxide and dicumyl peroxide, 2,2-azobis [2- (2-imidazolin-2-yl) propane] hydrogen dichloride, 2,2-azobis [2- (2-imidazoline- 2-yl) propane] disulfuric acid dihydrate, 2,2-azobis (2-amidinopropane) hydrogen dichloride, 2,2-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] water Japanese 2,2-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dichlorinated water 2,2-azobis [2- (2-imidazolin-2-yl) propane], 2,2-azobis (1-imino-1-pyrrolidino-2-ethylpropane) hydrogen dichloride, 2,2-azobis { 2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2, Azo compounds such as 2-azobis (N-hydroxyethylisobutyramide), 4,4-azobis (4-cyanopentanoic acid), azobisisobutyronitrile, azobis (2,4dimethylvaleronitrile), and the like. . The persulfates and organic peroxides include sodium sulfooxylate formaldehyde, sodium bisulfite, ammonium bisulfite, sodium thiosulfate, ammonium thiosulfate, hydrogen peroxide, sodium hydroxymethanesulfinate, L-ascorbic acid, And redox initiators using a reducing agent such as a salt thereof, a cuprous salt, and a ferrous salt in combination with a polymerization initiator. Persulfates and organic peroxides are particularly preferred in that the stability during polymerization is particularly excellent.

  The amount of the polymerization initiator used is not particularly limited because it depends on the type of monomer, the type of polymerization initiator, and the polymerization conditions, but is preferably 0.1% with respect to 100 parts by weight of the monomer component. -10 parts by weight.

  When the polymerization is performed by soap-free emulsion polymerization, the amount of the polymerization initiator used is not particularly limited because it depends on the type of monomer, the type of polymerization initiator, and the polymerization conditions. Preferably it is 0.1-10 weight part with respect to 100 weight part of components.

-Chain transfer agent In a 1st process, a chain transfer agent can be used as needed, and bridge | crosslinking can be accelerated | stimulated by this. The chain transfer agent may be used during the polymerization or may be used after the polymerization.

  When the polymerization in the first step is performed in multiple stages, a polyfunctional vinyl monomer is used as a monomer component only in the subsequent polymerization system after the second stage, and a chain transfer agent is introduced and used. Also good. Moreover, after completing the polymerization in the first step, a chain transfer agent may be introduced into the system to form a crosslink.

The chain transfer agent is not particularly limited, and a known chain transfer agent can be appropriately used depending on the type of monomer component used.
Specific examples of the chain transfer agent include thiol compounds and α-methylvinyl compounds.

  If necessary, the polymerization system can further contain a dispersion stabilizer, a polymerization inhibitor, and the like. Examples of the dispersion stabilizer include partially saponified polyvinyl alcohol; fully saponified polyvinyl alcohol; polyacrylic acid, a copolymer thereof, and a neutralized product thereof; polymethacrylic acid, a copolymer thereof, and a neutralized product thereof; Celluloses such as carboxymethylcellulose and hydroxypropylmethylcellulose; polyvinylpyrrolidone and the like. These dispersion stabilizers can be used alone or in combination of two or more. Examples of the polymerization inhibitor include sodium nitrite, hydroquinone, dibutylhydroxytoluene and the like. These polymerization inhibitors can be used alone or in combination of two or more.

<Second step>
In the second step of the method for producing the charge control agent-containing particles of the present invention, the vinyl monomer is polymerized in the presence of the charge control agent, and the charge control agent is formed on the core particles (core part) obtained in the first step. The shell (shell part) which consists of a polymer containing is formed.

  Examples of the vinyl monomer include the monomers exemplified in the description of the shell part of the charge control agent-containing particles. As the vinyl monomer used in the second step, a monofunctional vinyl monomer is preferably used, and a monofunctional (meth) acrylic monomer, a styrene monomer or the like is more preferably used. A vinyl-type monomer may be used individually by 1 type, and may be used in combination of 2 or more type.

  The polymerization of the vinyl monomer in the second step is not particularly limited, but can be performed by any polymerization method of soap-free emulsion polymerization, emulsion polymerization, suspension polymerization, or seed polymerization. Of these, seed polymerization is preferred.

  When the polymerization of the vinyl monomer in the second step is performed by seed polymerization, it is preferably performed in the absence of a surfactant and an emulsifier. In this case, the shell part of the obtained charge control agent-containing particles does not contain a surfactant and an emulsifier, which is preferable because the effect of the charge control agent is not adversely affected. In addition, when the first stage and second stage polymerizations are performed by soap-free emulsion polymerization, the resulting charge control agent-containing particles do not contain surfactants and emulsifiers, thereby suppressing the inclusion of impurities. It is particularly preferable because it does not adversely affect the effect of the charge control agent.

  In the second step, the vinyl monomer is polymerized in the presence of a charge control agent. The charge control agent may be introduced into the polymerization system at the time of polymerization of the vinyl monomer, and may be used by being dispersed in an aqueous medium, or may be used by being dissolved or dispersed in a vinyl monomer. However, it is preferably used by dissolving or dispersing in a vinyl monomer, and more preferably used by dissolving in a vinyl monomer. When the charge control agent is used by being dissolved or dispersed in a vinyl monomer, it is preferable because the charge control agent is efficiently taken into the formed shell.

-Charge control agent As a charge control agent, the thing similar to what was demonstrated of the shell part of a charge control agent containing particle | grain is used.
Among these, a charge control agent that dissolves or disperses in the vinyl monomer used in the second step can be preferably used, and a charge control agent that dissolves in the vinyl monomer can be particularly preferably used.

  When the charge control agent is dissolved or dispersed in a vinyl monomer, the amount of the charge control agent used is preferably based on 100 parts by weight of the vinyl monomer, although it depends on the type and thickness of the shell portion. Is preferably about 0.05 to 1 part by weight, more preferably about 0.05 to 0.3 part by weight.

  In the manufacturing method of the charge control agent containing particle | grains of this invention, in addition to a 1st process and a 2nd process, you may have another process. Specific examples of other steps include a dehydration step, a washing step, and a classification step. These other steps may be performed at any stage after the end of the second step, between the first step and the second step, in the steps of the first step and the second step.

  According to the method for producing a charge control agent-containing particle of the present invention, a charge control agent-containing particle in which a shell containing a charge control agent is formed in the second step on the core particle obtained in the first step is obtained. It is done. Therefore, according to the method for producing a charge control agent-containing particle of the present invention, the resulting charge control agent-containing particles are those in which the charge control agent is unevenly distributed in the shell portion of the particle, and the content of the charge control agent in the entire particle is Even when the amount is small, the effect of the charge control agent is sufficiently exhibited on the particle surface, and the charge amount is high.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
[Measurement and evaluation method]
In the following Examples and Comparative Examples, various properties are measured and evaluated as follows.
<Average particle size>
Using a scanning electron microscope, 100 particle diameters of the charge control agent-containing particles were measured, and the measurement results were obtained by arithmetic averaging.

<Charge amount (μC / g)>
Using a standard carrier for toner charge amount measurement (average particle size 50 μm) as a measurement carrier, the charge amount was measured by the following procedure using a blow-off charge measuring device. The measured value of the charge amount indicates that the larger the absolute value, the greater the charge.
(1) A standard carrier and fine particles to be measured are mixed in a ratio (weight ratio) of carrier: fine particles = 99.8: 0.2 to prepare a mixed powder.
(2) The mixed powder prepared in (1) is put into the Faraday cage of the blow-off charge measuring device.
(3) Compressed gas (N ₂ ) is ejected from the nozzle to the cage, and only the fine particles are blown out of the cage through the cage.
(4) The charge amount of the fine particles is determined by measuring the charge amount remaining in the carrier, and the charge amount per unit mass of the fine particles is calculated from the charged quantity.

[Example 1] (Production of charge control agent-containing particles without using an emulsifier)
A 1-liter flask was charged with 558 parts by weight of tap water and 12.5 parts by weight of methyl methacrylate, and was purged with nitrogen for 20 minutes while stirring at 200 rpm. Thereafter, the temperature was raised to 70 ° C., and 0.1 part by weight of potassium persulfate was added to initiate polymerization. After completion of the polymerization, 76.5 parts by weight of methyl methacrylate and 1 part by weight of ethylene glycol dimethacrylate (EGDMA) were added over 5 minutes. Thereafter, 0.4 parts by weight of potassium persulfate was added to perform polymerization, and core particles were generated in a suspended state.

  Next, 10 parts by weight of methyl methacrylate and 0.1 part by weight of a benzyl borate compound-based charge control agent (manufactured by Nippon Carlit Co., Ltd., product name: LR-147) are added in a state where the charge control agent is dissolved in methyl methacrylate. Then, after the polymerization in the second step, the temperature was raised to 90 ° C. and held for 1 hour to obtain charge control agent-containing particles as monodispersed fine particles. As a result of observation with a scanning electron microscope, the average particle size was 300 nm. The charge amount of the obtained charge control agent-containing particles is shown in Table 1.

[Example 2] (Production of charge control agent-containing particles without using an emulsifier)
A 1-liter flask was charged with 558 parts by weight of tap water and 12.5 parts by weight of methyl methacrylate, and was purged with nitrogen for 20 minutes while stirring at 200 rpm. Thereafter, the temperature was raised to 70 ° C., and 0.1 part by weight of potassium persulfate was added to initiate polymerization. After the completion of the polymerization, 74.5 parts by weight of methyl methacrylate and 3 parts by weight of ethylene glycol dimethacrylate (EGDMA) were added over 5 minutes. Thereafter, 0.4 parts by weight of potassium persulfate was added to perform polymerization, and core particles were generated in a suspended state.

  Next, 10 parts by weight of methyl methacrylate and 0.1 part by weight of a charge control agent (manufactured by Nippon Carlit Co., Ltd., product number: LR-147) were added in a state where the charge control agent was dissolved in methyl methacrylate, After the polymerization in the step, the temperature was raised to 90 ° C. and held for 1 hour to obtain charge control agent-containing particles as monodispersed fine particles. As a result of observation with a scanning electron microscope, the average particle size was 300 nm. The charge amount of the obtained charge control agent-containing particles is shown in Table 1.

[Example 3] (Production of charge control agent-containing particles using an emulsifier)
A 1-liter flask was charged with 558 parts by weight of tap water and 12.5 parts by weight of methyl methacrylate, and purged with nitrogen for 20 minutes while stirring at 200 rpm. Thereafter, the temperature was raised to 70 ° C., and 0.1 part by weight of potassium persulfate was added to initiate polymerization. After completion of the polymerization, 1 part by weight of a 10% aqueous solution of sodium dodecylbenzenesulfonate was added, and then 76.5 parts by weight of methyl methacrylate and 1 part by weight of ethylene glycol dimethacrylate were added over 5 minutes. Thereafter, 0.4 part by weight of potassium persulfate was added for polymerization. After completion of the polymerization, 10 parts by weight of methyl methacrylate and 0.1 part by weight of a charge adjusting agent (manufactured by Nippon Carlit Co., Ltd., product name: LR-147) were added for polymerization, and then the temperature was raised to 90 ° C. and held for 1 hour. As a result, monodispersed fine particles were obtained. As a result of observation with a scanning electron microscope, the average particle size was 300 nm.

[Comparative Example 1]
A flask having a capacity of 1 liter was charged with 325 parts by weight of tap water and 100 parts by weight of methyl methacrylate, and was purged with nitrogen for 20 minutes while stirring at 200 rpm. Thereafter, the temperature was raised to 70 ° C., and 0.5 part by weight of potassium persulfate was added to initiate polymerization. Polymerization was continued after 75 parts by weight of tap water was added 5 minutes after the addition of potassium persulfate. After completion of the polymerization, the temperature was raised to 90 ° C. and held for 1 hour to obtain monodispersed fine particles. As a result of observation with a scanning electron microscope, the average particle size was 300 nm. Table 1 shows the charge amount of the obtained monodispersed fine particles.

[Comparative Example 2]
A flask with a capacity of 1 liter was charged with 325 parts by weight of tap water and 90 parts by weight of methyl methacrylate, and was purged with nitrogen for 20 minutes while stirring at 200 rpm. Thereafter, the temperature was raised to 70 ° C., and 0.5 part by weight of potassium persulfate was added to initiate polymerization. When polymerization was continued by adding 75 parts by weight of tap water 5 minutes after the addition of potassium persulfate, core particles were produced in a suspended state.

  Next, 10 parts by weight of methyl methacrylate and 0.1 part by weight of a charge control agent (manufactured by Nippon Carlit Co., Ltd., product number: LR-147) are added in a state where the charge control agent is dissolved in methyl methacrylate, and polymerization is performed. Then, the temperature was raised to 90 ° C. and held for 1 hour to obtain charge control agent-containing particles as monodispersed fine particles. As a result of observation with a scanning electron microscope, the average particle size was 300 nm. The charge amount of the obtained charge control agent-containing particles is shown in Table 1.

[Comparative Example 3]
A flask having a capacity of 1 liter was charged with 558 parts by weight of tap water and 12.5 parts by weight of methyl methacrylate, and was purged with nitrogen for 20 minutes while stirring at 200 rpm. Thereafter, the temperature was raised to 70 ° C., and 0.1 part by weight of potassium persulfate was added to initiate polymerization. After completion of the polymerization, 77 parts by weight of methyl methacrylate and 0.4 parts by weight of ethylene glycol dimethacrylate were added over 5 minutes. Thereafter, 0.4 parts by weight of potassium persulfate was added to perform polymerization, and core particles were generated in a suspended state.

  Next, 10 parts by weight of methyl methacrylate and 0.1 part by weight of a charge control agent (manufactured by Nippon Carlit Co., Ltd., product number: LR-147) are added in a state where the charge control agent is dissolved in methyl methacrylate, and polymerization is performed. Then, the temperature was raised to 90 ° C. and held for 1 hour to obtain charge control agent-containing particles as monodispersed fine particles. As a result of observation with a scanning electron microscope, the average particle size was 300 nm. The charge amount of the obtained charge control agent-containing particles is shown in Table 1.

  In Examples 1 to 3, charge control agent-containing particles having a large absolute charge amount and excellent chargeability are obtained. Since Comparative Example 1 does not use a polyfunctional vinyl monomer and a charge control agent, the charge amount is −883 μC / g, which is a value that is significantly smaller than Examples 1 to 3. In Comparative Example 2, the charge control agent is added in the same number of parts as in the Example, but since a polyfunctional vinyl monomer is not used, the charge amount is -912 μC / g, compared with Examples 1 to 3. It is inferred that the absolute value is a small value and the charge control agent has migrated to the uncrosslinked core particles. In Comparative Example 3, 0.5% by weight of the polyfunctional vinyl monomer was used. However, the charge amount was still smaller than that in Examples 1 to 3, and the charge control agent was a core having a low degree of crosslinking. It is inferred that the particles have migrated. In Example 3, the core particles were prepared by emulsion polymerization. Since the polyfunctional vinyl monomer was used at 1% by weight, the absolute value of the charge amount was larger than that of the comparative example. Since the absolute value of the charge amount is smaller than in Examples 1 and 2, it is clear that it is preferable that no emulsifier is present.

  The charge control agent-containing particles according to the present invention are particularly preferably used as a material constituting a toner that is a powder developer for electrophotography.

Claims (7)

It contains 51 to 99.5% by weight of structural units derived from monofunctional vinyl monomers, 0.5 to 49% by weight of structural units derived from polyfunctional vinyl monomers, and is at least partially crosslinked. A core made of a polymer;
A charge control agent-containing particle having a shell portion made of a vinyl polymer containing a charge control agent.   The charge control agent-containing particles according to claim 1, which are substantially free of an emulsifier and a surfactant.   The charge control agent-containing particles according to claim 1 or 2, wherein the core part is obtained by soap-free emulsion polymerization. Monomer vinyl monomers are used in a proportion of 51 to 99.5% by weight, and polyfunctional vinyl monomers in a proportion of 0.5 to 49% by weight. Performing a first step of producing core particles;
Charge control agent-containing particles comprising: a second step of polymerizing a vinyl monomer in the presence of a charge control agent and forming a shell made of a polymer containing the charge control agent on the core particle. Manufacturing method.   The method for producing charge control agent-containing particles according to claim 4, wherein the vinyl monomer used in the second step is a monofunctional vinyl monomer.   6. The method for producing charge control agent-containing particles according to claim 4 or 5, wherein in the second step, the charge control agent is dissolved in a vinyl monomer and used.   7. The method for producing charge control agent-containing particles according to claim 4, wherein the polymerization in the first step is performed by soap-free emulsion polymerization.