JP6402529B2 - Toner and method for producing the same - Google Patents

Description

  The present invention relates to a toner.

Toner for developing an electrostatic image in electrophotography is used in printers, facsimiles, copying machines, and the like.
As the toner, particles having a binder, a colorant, a charge control agent and the like as main components are widely used. In many cases, an external additive adheres to the particle surface for the purpose of assisting the fluidity, developability, chargeability and the like of the toner. As the external additive, various inorganic particles and resin particles are used (for example, Patent Document 1).

  The toner accumulates positive or negative charges on the particle surface by frictional charging and is used for development of an electrostatic image (visualization of an electrostatic charge latent image). In order to perform development accurately, the charge amount needs to be an appropriate value. However, the conventional toner has insufficient charging stability, and the charge amount may vary greatly depending on the time for performing frictional charging.

JP 2007-248558 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a toner having excellent charging stability.

The toner of the present invention includes toner base particles containing a binder and resin particles (A),
The resin particles (A) are composed of a copolymer containing a structural unit based on the following hydrophobic monomer (a) and a structural unit based on the following hydrophilic monomer (b), The ratio of the structural unit based on the hydrophilic monomer (b) to the total of all the structural units is 5 to 40% by mass,
The average particle size of the resin particles (A) is 20 to 90 nm, the 90% particle size in the cumulative particle size distribution (volume basis) of the resin particles (A) is 130 nm or less,
Content of the said resin particle (A) is 0.3-5 mass parts with respect to 100 mass parts of said binders, It is characterized by the above-mentioned.
Hydrophobic monomer (a): at least one monomer selected from the group consisting of a styrene monomer and an alkyl (meth) acrylate.
Hydrophilic monomer (b): general formula _{^{CH 2 = CR 1 -COOR 2 OH}} (. However, ^{R 1} is hydrogen atom or a methyl group, ^{R 2} is an alkylene group having 1 to 4 carbon atoms) in At least one monomer selected from the group consisting of the represented compounds;

  According to the present invention, a toner having excellent charging stability can be provided.

The following definitions of terms apply throughout this specification and the claims.
“Structural unit” means a unit (monomer unit) formed by polymerization of monomers.
“(Meth) acrylic acid” is a general term for acrylic acid and methacrylic acid.

≪Toner≫
The toner of the present invention includes toner base particles containing a binder and resin particles (A).
The resin particles (A) are external additives and are attached to the surface of the toner base particles.
The toner of the present invention may further contain an external additive other than the resin particles (A) as long as it does not impair the effects of the present invention.

<Resin particles (A)>
A resin particle (A) consists of a copolymer containing the structural unit based on the following hydrophobic monomer (a), and the structural unit based on the following hydrophilic monomer (b).
The copolymer constituting the resin particle (A) may be a single monomer other than the hydrophobic monomer (a) and the hydrophilic monomer (b) as long as it does not impair the effects of the invention. It may further have a unit based on a body (hereinafter also referred to as “monomer (c)”).

Hydrophobic monomer (a):
The hydrophobic monomer (a) is at least one selected from the group consisting of a styrene monomer and a (meth) acrylic acid alkyl ester.

  Examples of the styrenic monomer include styrene, α-methylstyrene, o-, m- or p-methylstyrene, o-, m- or p-chlorostyrene.

The alkyl group in the (meth) acrylic acid alkyl ester may be linear or branched. 1-12 are preferable and, as for carbon number of this alkyl group, 1-8 are more preferable.
Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, and (meth) acrylic. Examples include hexyl acid, heptyl (meth) acrylate, and octyl (meth) acrylate.

  The hydrophobic monomer (a) may be used alone or in combination of two or more.

Hydrophilic monomer (b):
The hydrophilic monomer (b) is represented by the general formula CH ₂ = CR ¹ -COOR ² OH (where R ¹ is a hydrogen atom or a methyl group, and R ² is an alkylene group having 1 to 4 carbon atoms). It is at least 1 sort (s) chosen from the group which consists of a compound represented by these.

The number of carbon atoms of the alkylene group R ² is from 1 to 4, 2 carbon atoms are preferred. If the alkylene group has 4 or less carbon atoms, charge-up of the toner can be suppressed.
The alkylene group for R ² may be linear or branched.

Examples of the hydrophilic monomer (b) include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.
A hydrophilic monomer (b) may be used individually by 1 type, or may use 2 or more types together.

Monomer (c):
The monomer (c) is a monomer other than the hydrophobic monomer (a) and the hydrophilic monomer (b). As the monomer (c), any monomer that can be copolymerized with the hydrophobic monomer (a) and the hydrophilic monomer (b) may be used. For example, an anionic monomer, a cationic monomer, Nonionic monomers (however, excluding hydrophobic monomers (a) and hydrophilic monomers (b)) and the like.

As an anionic monomer, the monomer which has anionic functional groups, such as a carboxy group and a sulfonic acid group, is mentioned, For example, acrylic acid, methacrylic acid, maleic acid, sulfostyrene etc. are mentioned.
Examples of the cationic monomer include monomers containing a cationic functional group such as an amino group, an amide group, and a quaternary ammonium base.
Examples of the nonionic monomer (excluding the hydrophobic monomer (a) and the hydrophilic monomer (b)) include the following. “Monofunctional” means having one polymerizable double bond, and “polyfunctional” means having two or more polymerizable double bonds.
(Meth) alkoxyalkyl acrylate, (meth) acrylic acid ester having an alicyclic structure, (meth) acrylic acid hydroxyalkyl having a hydroxyalkyl group having 5 or more carbon atoms, other monofunctional vinyl-based monomers other than those Monofunctional monomers such as body;
Polyfunctional monomers such as polyfunctional (meth) acrylates, aromatic divinyl compounds, and other polyfunctional monomers other than these.

Examples of the alkoxyalkyl (meth) acrylate include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2- (n-propoxy) ethyl (meth) acrylate, and (meth) acrylic acid 2 -(N-butoxy) ethyl, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 2- (n-propoxy) propyl (meth) acrylate, 2- (meth) acrylic acid 2- ( n-butoxy) propyl and the like.
Examples of the (meth) acrylic acid ester having an alicyclic structure include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and isobornyl (meth) acrylate.
Examples of the hydroxyalkyl (meth) acrylate having a hydroxyalkyl group having 5 or more carbon atoms include 6-hydroxy n-hexyl (meth) acrylate.
Examples of other monofunctional vinyl monomers include vinyl acetate, vinyl propionate, vinyl chloride, and acrylonitrile.

Multifunctional (meth) acrylates include trimethylolpropane triacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, decaethylene glycol dimethacrylate, pentadecaethylene glycol dimethacrylate, pentacontaheptaethylene glycol dimethacrylate 1,3-butylene dimethacrylate, allyl methacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate and the like.
Examples of the aromatic divinyl compound include divinylbenzene, divinylnaphthalene, and derivatives thereof.
Examples of other polyfunctional monomers include N, N-divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfonic acid, polybutadiene, and polyisoprene unsaturated polyester.

A monomer (c) may be used individually by 1 type, or may use 2 or more types together.
As the monomer (c), a nonionic monomer is preferable, and a nonionic hydrophobic monomer is more preferable. Examples of the nonionic hydrophobic monomer include those having no hydroxy group among the aforementioned nonionic monomers.

composition:
The ratio of the structural unit based on the hydrophilic monomer (b) to the total of all structural units in the copolymer constituting the resin particles (A) is 5 to 40% by mass, and more preferably 8 to 30% by mass. . When the proportion of the structural unit based on the hydrophilic monomer (b) is within the above range, the resin particles (A) have an appropriate hygroscopic property, and the charging stability of the toner is excellent. If the proportion of the structural unit based on the hydrophilic monomer (b) is less than the lower limit of the range, the toner may be charged up, and if it exceeds the upper limit of the range, the toner may be charged down. The

  The proportion of the structural unit based on the hydrophobic monomer (a) to the total of all the structural units in the copolymer constituting the resin particle (A) is preferably 60 to 95% by mass, and more preferably 70 to 92% by mass. . When the proportion of the structural unit based on the hydrophobic monomer (a) is equal to or higher than the lower limit value of the range, toner charge-down can be suppressed, and when the ratio is equal to or lower than the upper limit value of the range, toner charge-up can be suppressed. .

The ratio of the total of the structural unit based on the hydrophobic monomer (a) and the structural unit based on the hydrophilic monomer (b) to the total of all structural units in the copolymer constituting the resin particles (A) is 98 mass% or more is preferable, and 99 mass% or more is more preferable. An upper limit is not specifically limited, 100 mass% may be sufficient.
When the total ratio of the structural unit based on the hydrophobic monomer (a) and the structural unit based on the hydrophilic monomer (b) is not less than the above lower limit value, the charging stability of the toner is more excellent.

  Even in the case of hydrophilic monomers, anionic monomers, cationic monomers, and nonionic monomers having a plurality of hydroxy groups are very strong in hydrophilicity, so that the hygroscopicity is increased by a small amount. If the hygroscopicity is too high, there is a concern about toner charge-down. Therefore, a nonionic monomer having a plurality of structural units based on anionic monomers, structural units based on cationic monomers, and a plurality of hydroxy groups with respect to the total of all structural units in the copolymer constituting the resin particles (A) The total proportion of the structural units based on the body is preferably 1% by mass or less, and particularly preferably 0% by mass. That is, the copolymer preferably does not contain a structural unit based on an anionic monomer, a structural unit based on a cationic monomer, and a nonionic monomer having a plurality of hydroxy groups.

  The number average molecular weight of the copolymer constituting the resin particles (A) is not particularly limited, but is usually 10,000 to 200,000, preferably 20,000 to 150,000. If the number average molecular weight is not less than the lower limit of the above range, the durability of the resin particles is more excellent. When the number average molecular weight is not more than the upper limit of the above range, the adhesion to the toner is more excellent. The number average molecular weight of the copolymer is a standard polystyrene equivalent value measured by gel permeation chromatography (GPC).

  Although the glass transition temperature of the copolymer which comprises a resin particle (A) is not specifically limited, Usually, it is 60 to 100 degreeC, and 70 to 90 degreeC is preferable. If the glass transition temperature is not less than the lower limit of the above range, blocking is unlikely to occur, and if it is not more than the upper limit, the low temperature fixability is excellent. The glass transition temperature of the copolymer is a value measured by differential scanning calorimetry (DSC).

The average particle diameter of the resin particles (A) is 20 to 90 nm, preferably 25 to 75 nm, and more preferably 30 to 60 nm.
When the average particle diameter of the resin particles (A) is not more than the above upper limit value, the resin particles (A) adhere tightly to the surface of the toner base particles, and the charging stability of the toner becomes better. If the average particle diameter of the resin particles (A) is not less than the lower limit of the above range, the production of the resin particles (A) is easy.
The average particle diameter of the resin particles (A) is a value measured by a dynamic light scattering particle diameter measuring apparatus.

The 90% particle size in the cumulative particle size distribution (volume basis) of the resin particles (A) is 130 nm or less. The 90% particle diameter is a particle diameter corresponding to 90% of the volume accumulation from the smaller particle diameter side, and is hereinafter referred to as “D90”. That is, D90 being 130 nm or less indicates that the proportion of particles having a particle diameter of 130 nm or more in the entire resin particles (A) is 10% by volume or less. If D90 is 130 nm or less, the resin particles (A) adhere tightly to the toner, and an excellent charging stability effect is obtained.
D90 is preferably 110 nm or less, and more preferably 90 nm or less.
The cumulative particle size distribution of the resin particles (A) is measured by a dynamic light scattering particle size measuring device.

(Method for producing resin particles)
The resin particles (A) can be produced by a known method such as emulsion polymerization, suspension polymerization, dispersion polymerization, etc., but the dispersion of resin particles satisfying the above average particle diameter and D90 can be used as a solvent. From the viewpoint of being easily obtained, it is preferable to produce by emulsion polymerization.

Examples of the emulsifier used in the emulsion polymerization include anionic emulsifiers such as fatty acid salts, alkyl sulfate esters and alkylbenzene sulfonates, cationic emulsifiers such as alkylamine salts and quaternary ammonium salts, and nonions such as polyoxyethylene alkyl ethers. Emulsifiers, and these may be used alone or in combination of two or more. The use amount of the emulsifier is preferably 0.3 to 8.0 parts by mass, more preferably 0.5 to 5.0 parts by mass with respect to 100 parts by mass in total of the monomers to be polymerized.
Examples of the polymerization initiator (hereinafter also simply referred to as initiator) used in emulsion polymerization include potassium persulfate, ammonium persulfate, and 2,2′-azobis (1-imino-1-pyrrolidino-2-methylpropane). Basic acid salts, 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (N- (2-carboxyethyl) -2-methylpropionamidine) hydrate, and the like. It may be used alone or in combination of two or more. The amount of the initiator used is preferably 0.05 to 3.0 parts by mass, and more preferably 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the total amount of monomers to be polymerized.
In the emulsion polymerization, in addition to the above-mentioned emulsifier and initiator, various additives used for known emulsion polymerization may be used.

(Content of resin particles (A))
In the toner of the present invention, the content of the resin particles (A) is 0.3 to 5 parts by mass, preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the binder in the toner base particles. When the content of the resin particles (A) is not less than the lower limit of the above range, the toner charge-up can be suppressed. If the content of the resin particles (A) is not more than the upper limit of the above range, toner charge-down can be suppressed. Further, since most of the resin particles (A) in the toner adhere to the surface of the toner base particles, the internal contamination of the copying machine or the like is hardly caused by the resin particles (A) not attached to the surface of the toner base particles.

<Toner base particles>
The toner base particles include a binder, and typically include a binder, a colorant, and a charge control agent. The toner base particles may contain an additive as necessary.

(Binder)
As the binder, for example, styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene, or the like, or a substituted polymer thereof; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene- Vinyl naphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer Styrene copolymers such as styrene-vinyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, etc. It is done.

  In addition to the above, polyvinyl chloride, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin Epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumaroindene resin, petroleum resin and the like can be used as the binder.

Furthermore, a crosslinked resin can also be used as the binder.
Examples of the crosslinking agent include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate; Examples include divinyl compounds such as aniline, divinyl ether, divinyl sulfide, and divinyl sulfone; compounds having two or more polymerizable double bonds, such as compounds having three or more vinyl groups.
These crosslinking agents may be used alone or in combination of two or more.

When the toner is used in a pressure fixing system, polyethylene, polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin are used as a binder. It is preferable to use a resin such as styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, or paraffin.
These binders may be used alone or in combination of two or more.

(Coloring agent)
The colorant is not particularly limited, and those generally used as toner colorants can be used. For example, carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6G, chalcoil blue, chrome yellow, quinacridone, benzidine yellow, rose bengal, triarylmethane And dyes, monoazo dyes, disazo dyes and the like. These colorants may be used alone or in combination of two or more.

  The content of the colorant in the toner base particles is preferably 2.0 to 10 parts by mass and more preferably 3.0 to 8.0 parts by mass with respect to 100 parts by mass of the binder.

(Charge control agent)
As the charge control agent, a positive charge control agent is used when the toner is used as a positive charge toner, and a negative charge control agent is used when the toner is used as a negative charge toner.

  The positive charge control agent is not particularly limited as long as it can control the toner to be positively charged, and a charge control agent generally used as a positive charge control agent for toner can be used. For example, modified nigrosine with nigrosine and fatty acid metal salts, polymers containing quaternary ammonium salts and quaternary ammonium bases, polymers containing phosphonium salts and phosphonium bases, triphenylmethane dyes and their lake pigments, Examples include fatty acid metal salts, diorganotin oxide, and diorganotin borate. These positive charge control agents may be used alone or in combination of two or more.

  The negative charge control agent is not particularly limited as long as it can control the toner to negative charge, and a charge control agent generally used as a negative charge control agent for toner can be used. Examples thereof include a monoazo metal compound, an acetylacetone metal compound, an aromatic hydroxycarboxylic acid, and an aromatic dicarboxylic acid metal compound. These negative charge control agents may be used individually by 1 type, and may use 2 or more types together.

  The content of the charge control agent in the toner base particles is preferably 2.0 to 15 parts by mass, and more preferably 3.0 to 10 parts by mass with respect to 100 parts by mass of the binder.

(Additive)
Examples of additives include lubricants such as zinc stearate, abrasives such as cerium oxide and silicon carbide, fluidity imparting agents such as aluminum oxide, anti-caking agents, and conductivity imparting agents such as carbon black and tin oxide. It is done.
In order to improve releasability at the time of fixing with a hot roll, waxy substances such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, sazol wax, paraffin wax and the like may be included. The content of the wax-like substance is preferably about 0.5 to 5% by mass in 100% by mass of the toner base particles.

The average particle size of the toner base particles is preferably 5.0 to 15 μm, and more preferably 6.0 to 12 μm.
The average particle size of the toner base particles can be measured using, for example, a laser diffraction particle size measuring device SALD-3100 (manufactured by Shimadzu Corporation).

<Other external additives>
Examples of other external additives include inorganic oxide fine particles such as silica, titania, alumina, strontium titanate, and tin oxide.
The content of other external additives is preferably 2.0 parts by mass or less, and more preferably 1.0 part by mass or less with respect to 100 parts by mass of the toner base particles.

<Toner production method>
The method for producing the toner of the present invention is not particularly limited as long as the resin particles (A) can adhere to the surface of the toner base particles, and examples thereof include the following production methods.
First, a binder, a colorant, a charge control agent, and an additive as necessary are mixed, melt-kneaded, and cooled and solidified. Next, the solidified product is pulverized with a pulverizer, and the obtained pulverized product is classified to produce toner mother particles having a predetermined average particle size. Next, resin particles (A) and, if necessary, other external additives are added to the obtained toner base particles to obtain a toner.
A magnetic material may be added to the toner thus obtained as necessary. A toner to which a magnetic material is added can be used as a magnetic toner.

<Effect>
The toner of the present invention described above is excellent in charging stability because it contains 0.3 to 5 parts by mass of the resin particles (A) with respect to 100 parts by mass of the binder. The reason is as follows.
Since the copolymer constituting the resin particles (A) contains the hydrophilic monomer (b) at a predetermined content, it has moderate hygroscopicity. When such resin particles (A) adhere to the surface of the toner base particles as an external additive, water is adsorbed on the surface of the toner, and charge up of the toner is suppressed by the moisture. Further, since the amount of adsorbed water is very small, toner charge-down hardly occurs. Further, since the resin particles (A) have the above average particle diameter and D90, they easily adhere to the surface of the toner base particles. It is considered that an excellent charging stability effect can be obtained by these acting synergistically.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
In the following examples, “part” represents “part by mass”. Examples 3 and 10 to 11 are reference examples.

(Production Example 1: Production of resin particles (A-1))
Dissolve 2.8 parts of sodium dodecylbenzenesulfonate and 0.7 part of polyoxyethylene (12) lauryl ether in 1,000 parts of ion-exchanged water in a four-necked flask equipped with a stirrer, condenser, thermometer and nitrogen inlet tube. I let you. 1/10 of the monomer solution obtained by mixing 76 parts of methyl methacrylate, 9 parts of 2-ethylhexyl acrylate, and 15 parts of 2-hydroxyethyl methacrylate was added and stirred for emulsification. Thereafter, the temperature was raised to 80 ° C. under nitrogen, 0.5 part of potassium persulfate and 10 parts of ion-exchanged water were added, and the remaining monomer solution was added dropwise over 1 hour. Subsequently, after making it react at 80 degreeC for 3 hours, it heated up to 85 degreeC, and also stirred for 3 hours, and obtained the copolymer emulsion (a-1).
The average particle diameter of the resin particles (A-1) contained in the copolymer emulsion (a-1) and the 90% particle diameter (D90) of the cumulative particle size distribution are calculated using a dynamic light scattering particle diameter measuring apparatus FPAR-1000 ( The average particle diameter was 45 nm and D90 was 75 nm as measured by Otsuka Electronics Co., Ltd.

(Production Examples 2 to 14: Production of resin particles (A-2) to (A-14))
Copolymer emulsions (a-2) to (a-14) in the same manner as in Production Example 1 except that the hydrophobic monomer, hydrophilic monomer, emulsifier and initiator were changed as shown in Table 1, respectively. ) Table 1 shows the average particle diameter, D90, of the resin particles (A-2) to (A-14) in this copolymer emulsion.
Table 1 shows the amounts (parts) of each of the hydrophobic monomer, the hydrophilic monomer, the emulsifier, and the initiator when the total amount of monomers to be polymerized is 100 parts.

Example 1
100 parts polyester resin (DZ200 made by DIC), 8 parts positive charge control agent (FCA-201PS made by Fujikura Kasei), 4 parts copper phthalocyanine-based oil-soluble dye (Spilion Blue 2BNH made by Hodogaya Chemical Co., Ltd.), Carnauba Wax (Yoyuki Kato) 4 parts) were blended. The mixture thus obtained was melt-kneaded in a lab plast mill (manufactured by Toyo Seiki Seisakusho), pulverized in a jet mill (manufactured by Nippon Pneumatic Industry), and the obtained pulverized product was classified to give a particle size of 5 to 15 μm Polyester toner base particles (B-1) were produced. After adding 1 part (converted to solid content) of the copolymer emulsion (a-1) to this (B-1) and treating it with a Henschel mixer (manufactured by Nippon Coke Industries), it was dried in a hot air drying oven at 40 ° C. Was pulverized again to obtain a positively charged toner.

(Example 2)
100 parts of styrene acrylic copolymer resin (FSR-018 manufactured by Fujikura Kasei), 5 parts of positive charge control agent (FCA-201PS manufactured by Fujikura Kasei), 4 parts of carbon black (MA # 100 manufactured by Mitsubishi Chemical), Biscol 550P (Sanyo Kasei) 3 parts) were blended. The mixture thus obtained was melt-kneaded in a lab plast mill (manufactured by Toyo Seiki Seisakusho), pulverized in a jet mill (manufactured by Nippon Pneumatic Industry), and the obtained pulverized product was classified to give a particle size of 5 to 15 μm Styrene acrylic toner mother particles (B-2). After adding 1 part (converted to solid content) of the copolymer emulsion (a-1) to this (B-2) and treating it with a Henschel mixer (manufactured by Nippon Coke Industries), it was dried in a hot air drying oven at 40 ° C. Was pulverized again to obtain a positively charged toner.

(Examples 3-12, Comparative Examples 1-8)
The type of copolymer emulsion to be added to the polyester toner base particles (B-1) corresponds to the resin particles shown in Table 2, and the addition amount of the copolymer emulsion (in terms of solid content) is determined as binder 100. A positively charged toner was obtained in the same manner as in Example 1, except that the resin particle content (parts) relative to the parts was the values shown in Tables 2-3.

  For the positively charged toners of Examples 1 to 12 and Comparative Examples 1 to 8, the charging stability was evaluated as follows. The results are shown in Tables 2-3.

(Charge stability)
5 parts of a positively charged toner were blended with 100 parts of carrier (F-921-60 manufactured by Powdertech Co., Ltd.), and triboelectrically charged for 1 hour in an environment of a temperature of 22 ° C. and a relative humidity of 60%. Thereafter, the charge amount (hereinafter referred to as charge amount (1)) was measured using a blow-off powder charge amount measuring device (manufactured by Toshiba Chemical).
Separately, the positively charged toner was frictionally charged in the same manner as described above except that the time for friction charging was 10 hours, and the charge amount (hereinafter referred to as charge amount (10)) was measured.
From the above results, the change rate (%) of the charge amount was calculated by the following formula. If the rate of change is within a range of −10 to + 30%, the toner has practicality. If the change rate is less than −10%, fogging occurs, and if it exceeds + 30%, there is a concern that the image density is lowered.
Rate of change = 100 × {charge amount (10) −charge amount (1)} / charge amount (1)

The meanings of the abbreviations in Table 1 are as follows.
MMA: methyl methacrylate BA: n-butyl acrylate 2-EHA: 2-ethylhexyl acrylate HEMA: 2-hydroxyethyl methacrylate.
HEA: 2-hydroxyethyl acrylate.
4-HBMA: 4-hydroxybutyl methacrylate.
6-HHA: 6-hydroxyhexyl acrylate.
PEG-MA: Polyethylene glycol (8) monomethacrylate. In addition, (8) shows that the average number of repetitions of (CH ₂ CH ₂ O) in polyethylene glycol is 8.
NaSS: Sodium styrene sulfonate.
DBS: sodium dodecylbenzenesulfonate.
DTAC: dodecyltrimethylammonium chloride.
PODE: polyoxyethylene (12) lauryl ether. In addition, (12) indicates that the average number of repeating ethyleneoxy groups (CH ₂ CH ₂ O) is 12.
KPS: potassium persulfate.
APS: ammonium persulfate.
AIPMP: 2,2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) dibasic acid salt.

As shown in the above results, the positively charged toners of Examples 1 to 12 are excellent in charging stability because the charge rate change rate is within a range of −10 to + 30% and both charge-up and charge-down are suppressed. It was.
The positively charged toner of Comparative Example 1 in which the content of the resin particles (A-1) was 0.2 parts with respect to 100 parts of the binder showed a significant charge-up.
The positively charged toner of Comparative Example 2 in which the content of the resin particles (A-1) was 7.0 parts with respect to 100 parts of the binder showed a significant charge down.
The positively charged toner of Comparative Example 3 using resin particles (A-9) having a content of structural units based on HEMA of 3% by mass showed a significant charge-up.
The positively charged toner of Comparative Example 4 using resin particles (A-10) having a constitutional unit content based on HEMA of 50% by mass showed significant charge-down.
The positively charged toner of Comparative Example 5 using resin particles (A-11) having an average particle diameter of 117 nm and D90 of 159 nm showed a significant charge-up.
The positively charged toner of Comparative Example 6 using resin particles (A-12) whose hydrophilic monomer is 6-HHA showed a significant charge-up.
Comparative Example 7 using resin particles (A-13) in which the hydrophilic monomer is PEG-MA, Resin particles (A-14) in which the hydrophilic monomer is NaSS of an anionic monomer were used. The positively charged toner of Comparative Example 8 showed a significant charge down.

Claims (2)

Including toner base particles containing a binder and resin particles (A),
The resin particles (A) are composed of a copolymer containing a structural unit based on the following hydrophobic monomer (a) and a structural unit based on the following hydrophilic monomer (b), The ratio of the structural unit based on the hydrophilic monomer (b) to the total of all the structural units is 5 to 40% by mass, and the hydrophobic monomer (a ) And the total proportion of the structural unit based on the hydrophilic monomer (b) is 98% by mass or more,
The average particle size of the resin particles (A) is 25 to 75 nm, and the 90% particle size in the cumulative particle size distribution (volume basis) of the resin particles (A) is 110 nm or less,
The toner, wherein the content of the resin particles (A) is 0.5 to 5 parts by mass with respect to 100 parts by mass of the binder.
Hydrophobic monomer (a): at least one monomer selected from the group consisting of a styrene monomer and an alkyl (meth) acrylate.
Hydrophilic monomer (b): general formula _{^{CH 2 = CR 1 -COOR 2 OH}} (. However, ^{R 1} is hydrogen atom or a methyl group, ^{R 2} is an alkylene group having 1 to 4 carbon atoms) in At least one monomer selected from the group consisting of the represented compounds; A method for producing the toner according to claim 1 ,
A monomer containing the hydrophobic monomer (a) and the hydrophilic monomer (b) is used by using 0.5 to 5.0 parts by mass of an emulsifier with respect to 100 parts by mass of the monomer. Emulsion polymerization to produce the resin particles (A);
Attaching the resin particles (A) to the surface of the toner base particles;
A method for producing a toner comprising: