JP2023125146A - toner - Google Patents

Abstract

To provide a toner which is excellent in follow-up property of a solid image, can suppress occurrence of fog under high temperature and high humidity, and has good storage property.SOLUTION: A toner contains colored resin particles containing a binder resin, a coloring agent, a softening agent, and a charge control agent, and an external additive, wherein an ester wax which is a condensate of polyhydric alcohol and a straight-chain carboxylic acid and has a hydroxyl value of 3.0 mgKOH/g or more and less than 7.0 mgKOH/g is contained as the softening agent, and a blow-off charging amount of the colored resin particles measured by a specific charging amount measurement method is 15 μC/g or more and 60 μC/g or less.SELECTED DRAWING: None

Description

The present disclosure relates to toners used for developing electrostatic latent images in electrophotography, electrostatic recording, electrostatic printing, and the like.

In image forming devices such as electrophotographic devices, electrostatic recording devices, and electrostatic printing devices, an electrostatic latent image formed on a photoreceptor is developed with toner, and the toner image is transferred onto a transfer material such as paper. After that, a fixed image is formed by fixing by heating or the like.
Such image forming apparatuses are desired to be compatible with high image quality and high speed printing, and toners that can form high quality images are also desired.

Toner usually contains toner wax as a softener or release agent in order to improve releasability from the fixing roll.
For example, Patent Document 1 describes that it is obtained by a condensation reaction between a specific linear saturated monocarboxylic acid and a specific monohydric or polyhydric alcohol, and the maximum peak temperature is in the range of 55°C to 90°C in a differential thermal curve. discloses a toner containing an ester wax having an acid value of 3 mgKOH/g or less and a hydroxyl value of 5 mgKOH/g or less.

Patent Document 2 discloses a toner containing an ester wax obtained by an esterification reaction between pentaerythritol and a monocarboxylic acid containing behenic acid, arachidic acid, and stearic acid in specific proportions.

On the other hand, Patent Document 3 contains colored resin particles containing a binder resin, carbon black, and a quaternary ammonium base-containing copolymer as a charge control resin, and the blow-off charge amount of the colored resin particles is 5 to 60 μC/ A positively chargeable black toner is disclosed that has a range of g.

Japanese Patent Application Publication No. 2002-212142 JP2020-60681A International Publication No. 2017/170278

However, the toners disclosed in Patent Documents 1 to 3 have a problem of insufficient solid followability. Solid pattern tracking improves when the amount of charge on the toner is reduced, but even if the amount of charge on the toner is reduced, fogging is more likely to occur in high temperature and high humidity environments. problem occurs. Furthermore, even if the amount of charge of the toner is reduced, the solid pattern followability may not be sufficiently improved in some cases.
Furthermore, toners capable of forming high-quality images are required to have excellent storage stability.

An object of the present disclosure is to provide a toner that has excellent solid followability, can suppress the occurrence of fogging under high temperature and high humidity, and has good storage stability.

As a result of extensive research to solve the above problems, the present inventors have discovered that an ester wax, which is a condensation product of polyhydric alcohol and linear carboxylic acid and has a hydroxyl value within a specific range, is used as a softening agent. It has been found that the above-mentioned problem can be solved by using the method and further controlling the amount of blow-off charge of the colored resin particles measured by a specific method within a specific range.

That is, the toner of the present disclosure is a toner containing colored resin particles containing a binder resin, a colorant, a softener, and a charge control agent, and an external additive,
The softener includes an ester wax that is a condensate of a polyhydric alcohol and a linear carboxylic acid and has a hydroxyl value of 3.0 mgKOH/g or more and less than 7.0 mgKOH/g,
The colored resin particles have a blow-off charge amount of 15 μC/g or more and 60 μC/g or less, as measured by the charge amount measuring method described below.

[Charge amount measurement method]
0.25 g of colored resin particles and 9.75 g of a spherical uncoated Mn-Mg-Sr-Fe ferrite carrier with an average particle diameter of 60 μm were placed in a glass container with a volume of 30 cc (inner dimensions: bottom diameter: 30 mm, height: 50 mm). The colored resin particles are placed in a manufactured container and rotated at 160 rpm for 30 minutes using a roller stirrer, and subjected to triboelectric charging treatment in an environment of 23° C. and 50% relative humidity. 0.2 g of the mixture of the above-mentioned ferrite carrier and the above-mentioned ferrite carrier were put into a Faraday cage, and blow-off was performed for 30 seconds at a nitrogen gas pressure of 0.098 MPa using a blow-off powder charge measuring device to determine the blow-off charge amount of the colored resin particles. (μC/g).

In the toner of the present disclosure, the ester wax may be a condensate of a tetrahydric alcohol and a linear monocarboxylic acid.

In the toner of the present disclosure, the acid value of the ester wax may be 1.0 mgKOH/g or less.

In the toner of the present disclosure, the charge control agent includes a styrene-acrylic copolymer containing a quaternary ammonium base-containing (meth)acrylate monomer unit; The copolymerization ratio of (meth)acrylate monomer units is 0.1% by mass or more and 3.0% by mass or less, and the content of the styrene-acrylic copolymer is based on 100 parts by mass of the binder resin, It may be 4.8 parts by mass or more and 15.0 parts by mass or less.

In the toner of the present disclosure, the volume average particle diameter of the colored resin particles may be 6.0 μm or more and 8.0 μm or less.

According to the present disclosure as described above, it is possible to provide a toner that has excellent solid followability, can suppress the occurrence of fogging under high temperature and high humidity, and has good storage stability.

The toner of the present disclosure is a toner containing colored resin particles including a binder resin, a colorant, a softener, and a charge control agent, and an external additive, and includes:
The softener includes an ester wax that is a condensate of a polyhydric alcohol and a linear carboxylic acid and has a hydroxyl value of 3.0 mgKOH/g or more and less than 7.0 mgKOH/g,
The colored resin particles have a blow-off charge amount of 15 μC/g or more and 60 μC/g or less, as measured by a specific charge amount measuring method described below.

The higher the hydroxyl value of the ester wax contained in the toner, the lower the heat resistance temperature of the toner tends to be, thereby making it more likely that blocking will occur during toner storage, that is, the storage stability will deteriorate. Therefore, it has conventionally been thought that the lower the hydroxyl value of the ester wax is, the more desirable it is. The ester wax used in the toners of Patent Documents 1 and 2 is obtained by condensing an excess amount of carboxylic acid with alcohol as a raw material. Since polyhydric alcohols have good reactivity, ester waxes obtained by a condensation reaction between polyhydric alcohols and an excess amount of carboxylic acid usually have a hydroxyl value of less than 3.0 mgKOH/g. The ester wax (trade name: WE-6, manufactured by NOF Corporation) used in each example of Patent Document 3 is the same as the ester wax used in Comparative Examples 5 and 6, which will be described later. The value is 1.6 mgKOH/g. However, the present inventor has found that when the hydroxyl value of the ester wax contained in the toner is 3.0 mgKOH/g or more, it is possible to improve the solid followability when a solid image is formed. On the other hand, the present inventor found that when a monohydric alcohol is used as a raw material alcohol, it is easy to obtain an ester wax with a hydroxyl value of 3.0 mgKOH/g or more, but the resulting ester wax tends to have a high acid value. I found out that there is. Toners containing ester waxes with high acid values have problems such as easy formation of coarse particles and poor storage stability or environmental stability. There is also the problem that there is a possibility that volatile organic compounds (VOC) and volatile organic compounds (VOC) may be generated. In contrast, the toner of the present disclosure contains an ester wax that is a condensate of a polyhydric alcohol and a linear carboxylic acid and has a hydroxyl value of 3.0 mgKOH/g or more and less than 7.0 mgKOH/g. , is a toner with improved solid followability without having the above-mentioned problems. Furthermore, the toner of the present disclosure has a blow-off charge amount of colored resin particles of 15 μC/g or more and 60 μC/g or less as measured by a specific charge amount measurement method described later, and has an appropriate charge amount, so it is an excellent solid toner. While maintaining followability, it is possible to suppress the occurrence of fog under high temperature and high humidity conditions.

Hereinafter, a method for manufacturing the colored resin particles contained in the toner of the present disclosure, colored resin particles obtained by the manufacturing method, and the toner of the present disclosure will be described in order.
In addition, in the present disclosure, "~" in a numerical range means that the numerical values described before and after it are included as a lower limit value and an upper limit value.

1. Methods for producing colored resin particles In general, methods for producing colored resin particles are roughly divided into dry methods such as pulverization methods, and wet methods such as emulsion polymerization aggregation methods, suspension polymerization methods, and dissolution suspension methods. The wet method is preferable because it is easy to obtain a toner with excellent printing properties such as printing properties. Among wet methods, polymerization methods such as emulsion polymerization aggregation method and suspension polymerization method are preferable because it is easy to obtain toner with a relatively small particle size distribution on the micron order. preferable.

In the emulsion polymerization aggregation method, emulsified polymerizable monomers are polymerized to obtain a fine resin particle emulsion, which is then aggregated with a colorant dispersion liquid and the like to produce colored resin particles. In addition, in the above dissolution suspension method, a solution in which toner components such as a binder resin and a colorant are dissolved or dispersed in an organic solvent is formed into droplets in an aqueous medium, and the organic solvent is removed to produce colored resin particles. A known method can be used for each method.

The colored resin particles contained in the toner of the present disclosure can be manufactured using a wet method or a dry method. When producing colored resin particles by employing the (A) suspension polymerization method, which is preferable among the wet methods, or by employing the (B) pulverization method, which is typical among the dry methods, the following process is performed.

(A) Suspension polymerization method (A-1) Preparation process of polymerizable monomer composition First, a polymerizable monomer, a colorant, a softener, and a charge control agent, and further added as necessary to adjust the molecular weight. A polymerizable monomer composition is prepared by mixing other additives such as additives. For example, a media type disperser is used for mixing when preparing the polymerizable monomer composition.

In the present disclosure, a polymerizable monomer refers to a monomer having a polymerizable functional group, and the polymerizable monomer is polymerized to become a binder resin. It is preferable to use a monovinyl monomer as the main component of the polymerizable monomer. Examples of monovinyl monomers include styrene; styrene derivatives such as vinyltoluene and α-methylstyrene; acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-acrylic acid. - 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; acrylonitrile , and nitrile compounds such as methacrylonitrile; amide compounds such as acrylamide and methacrylamide; and olefins such as ethylene, propylene, and butylene. These monovinyl monomers can be used alone or in combination of two or more. Among these, styrene, styrene derivatives, and acrylic esters or methacrylic esters are preferably used as monovinyl monomers.

In order to improve hot offset and storage stability, it is preferable to use any crosslinkable polymerizable monomer together with the monovinyl monomer. A crosslinkable polymerizable monomer refers to a monomer having two or more polymerizable functional groups. Examples of crosslinkable polymerizable monomers include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; alcohols having two or more hydroxyl groups such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; Ester compounds in which two or more carboxylic acids having carbon-carbon double bonds are ester-bonded; other divinyl compounds such as N,N-divinylaniline and divinyl ether; compounds having three or more vinyl groups; etc. can be mentioned. These crosslinkable polymerizable monomers can be used alone or in combination of two or more.
In the present disclosure, the crosslinkable polymerizable monomer is generally used in a proportion of 0.1 to 5 parts by weight, preferably 0.3 to 2 parts by weight, based on 100 parts by weight of the monovinyl monomer. desirable.

Further, it is preferable to use a macromonomer as a part of the polymerizable monomer because the resulting toner has a good balance between storage stability and low-temperature fixability.
Examples of macromonomers include reactive oligomers and polymers that have a polymerizable carbon-carbon unsaturated double bond at the end of the molecular chain and have a number average molecular weight of usually 1,000 to 30,000. can be mentioned. Examples of the macromonomer include styrene macromonomer, styrene-acrylonitrile macromonomer, polyacrylate macromonomer, and polymethacrylate macromonomer. Among them, at least one selected from polyacrylic acid ester macromonomers and polymethacrylic acid ester macromonomers can be preferably used. Examples of the acrylic ester used in the polyacrylic ester macromonomer include those similar to the acrylic ester that can be used as the monovinyl monomer, and methacrylic ester used in the polymethacrylic ester macromonomer. Examples of the ester include the same methacrylic esters that can be used as the monovinyl monomer. As the macromonomer, it is preferable to appropriately select and use a macromonomer that, when included in the polymerizable monomer, gives a higher glass transition temperature (Tg) of the resulting binder resin than when it is not included. preferable.
As the macromonomer, a commercially available product may be used. Examples of commercially available macromonomers include Macromonomer series AA-6, AS-6, AN-6S, AB-6, and AW-6S manufactured by Toagosei Co., Ltd.
The macromonomers can be used alone or in combination of two or more.
When the polymerizable monomer contains the macromonomer, the content of the macromonomer is not particularly limited, but is preferably 0.03 to 5 parts by weight based on 100 parts by weight of the monovinyl monomer. , more preferably 0.05 to 1 part by mass.

The content of the polymerizable monomer is not particularly limited, but is preferably 60 to 95 parts by mass, more preferably 65 to 95 parts by mass, based on 100 parts by mass of the total solid content contained in the polymerizable monomer composition. The amount is 90 parts by weight, more preferably 70 to 85 parts by weight.
Note that in the present disclosure, the solid content refers to all components other than the solvent, and liquid monomers and the like are also included in the solid content.

As the colorant, colorants conventionally used in toners can be appropriately selected and used, and there are no particular limitations. When producing color toners, black, cyan, yellow, and magenta colorants can be used.
As the black colorant, for example, carbon black, titanium black, magnetic powder such as iron zinc oxide, iron nickel oxide, etc. can be used.
As the cyan colorant, for example, phthalocyanine pigments such as copper phthalocyanine pigments and derivatives thereof, cyan pigments such as anthraquinone pigments, cyan dyes, etc. can be used. Specifically, for example, C. I. Pigment Blue 2, 3, 6, 15, 15:1, 15:2, 15:3, 15:4, 16, 17:1, 60; C.I. I. Examples include Solvent Blue 70.
As the yellow colorant, for example, azo pigments such as monoazo pigments and disazo pigments, yellow pigments such as condensed polycyclic pigments, yellow dyes, etc. can be used. Specifically, for example, C. I. Pigment Yellow 3, 12, 13, 14, 15, 17, 62, 65, 73, 74, 83, 93, 97, 120, 138, 155, 180, 181, 185, 186, 213, 214; I. Examples include Solvent Yellow 98 and 162.
As the magenta colorant, for example, azo pigments such as monoazo pigments and disazo pigments, magenta pigments such as condensed polycyclic pigments such as quinacridone pigments, and magenta dyes can be used. Specifically, for example, C. 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, 237, 238, 251, 254, 255, 269; C. I. Pigment Violet 19; C. I. Solvent red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121; C.I. I. Dispersed Red 9; C. I. Solvent Violet 8, 13, 14, 21, 27; C.I. I. Disperse Violet 1; C. I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40; C. I. Examples include basic violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28, and the like.
The coloring agents may be used alone or in combination of two or more.

In the present disclosure, it is preferable to contain carbon black as a colorant in order to more effectively exhibit the effect of improving solid followability. When carbon black is contained, the content of carbon black is preferably 10 to 15 parts by weight, more preferably 10 to 13 parts by weight, based on 100 parts by weight of the polymerizable monomer. Further, the content of carbon black in the toner is preferably 10 to 15 parts by weight, more preferably 10 to 13 parts by weight, based on 100 parts by weight of the binder resin.
Further, the content of the colorant is not particularly limited, but is preferably 10 to 15 parts by weight, more preferably 10 to 13 parts by weight, based on 100 parts by weight of the polymerizable monomer. Further, the content of the colorant in the toner is preferably 10 to 15 parts by weight, more preferably 10 to 13 parts by weight, based on 100 parts by weight of the binder resin.
When the content of the colorant is within the above range, sufficient image density can be obtained, and the effect of improving solid pattern followability according to the present disclosure can be effectively exhibited.

In the present disclosure, as a softening agent, an ester wax (simply referred to as " (sometimes referred to as "specific ester waxes") are used.
The polyhydric alcohol is not particularly limited, but di- to hexa-hydric polyhydric alcohols are preferably used. Examples of dihydric alcohols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, Examples include diethylene glycol, 2,2,4-trimethyl-1,3-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,4-phenylene glycol, bisphenol A, and the like. Examples of the trihydric alcohol include 1,2,4-butanetriol, 1,2,5-pentanetriol, 2-methyl-1,2,4-butanetriol, glycerin, 2-methylpropanetriol, and trimethylol. Examples include ethane, triethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene. Examples of the tetrahydric alcohol include 1,2,3,6-hexanetetrol and pentaerythritol. Examples of the pentavalent alcohol include glucose and the like. Examples of the hexavalent alcohol include dipentaerythritol. These polyhydric alcohols can be used alone or in combination of two or more.
Among the polyhydric alcohols, trihydric to pentavalent polyhydric alcohols are preferred, tetrahydric polyhydric alcohols are more preferred, and pentaerythritol is preferred, from the viewpoint of easily obtaining an ester wax having a desired hydroxyl value and acid value. Particularly preferred.

As the linear carboxylic acid, a linear saturated monocarboxylic acid is preferably used. Further, as the straight chain carboxylic acid, one having 16 to 24 carbon atoms is preferable. Suitable straight-chain carboxylic acids include, for example, palmitic acid, stearic acid, eicosanoic acid, behenic acid, lignoceric acid, and among others, stearic acid is preferred.

The above specific ester wax has a hydroxyl value of 3.0 mgKOH/g or more and less than 7.0 mgKOH/g. When the hydroxyl value of the ester wax is 3.0 mgKOH/g or more, it is possible to improve the solid followability, and when it is less than 7.0 mgKOH/g, the toner has good storage stability. I can do it. From the viewpoint of the balance between solidity and preservability, the hydroxyl value of the ester wax is preferably 6.0 mgKOH/g or less, more preferably 5.0 mgKOH/g or less, even more preferably 4.0 mgKOH/g or less.

Further, the above-mentioned specific ester wax preferably has an acid value of 1.0 mgKOH/g or less, more preferably 0.7 mgKOH/g or less, still more preferably 0.5 mgKOH/g or less. When the acid value of the ester wax is below the above upper limit value, generation of coarse particles can be suppressed, and thus image quality defects such as filming and white spots can be suppressed. Furthermore, when the acid value of the ester wax is at most the above upper limit, it is possible to suppress deterioration of toner storage stability and environmental stability, and furthermore, it is possible to suppress the generation of UFPs and VOCs.
The hydroxyl value and acid value of the softener are values measured in accordance with JIS K 0070, which is a standard oil and fat analysis method established by the Japan Industrial Standards Committee (JICS).

The hydroxyl value and acid value of the ester wax depend on the type of polyhydric alcohol and linear carboxylic acid used as raw materials. A desired value can be obtained by adjusting the reaction temperature or reaction conditions such as the reaction temperature and reaction time of the condensation reaction.
In order to obtain the above-mentioned specific ester wax, when using a divalent to hexavalent polyhydric alcohol, the amount of carboxy groups in the linear carboxylic acid used in the condensation reaction is 0.94 per equivalent of hydroxyl group in the polyhydric alcohol. The amount is preferably 1.04 to 1.04 equivalents. When using a particularly preferred tetrahydric alcohol, the amount of carboxy groups in the linear carboxylic acid used in the condensation reaction is preferably 0.95 to 1.01 equivalents per 1 equivalent of hydroxyl groups.
Further, in order to obtain the above-mentioned specific ester wax, it is preferable that the reaction temperature of the condensation reaction is 200 to 240°C and the reaction time is 10 to 18 hours.

The condensation reaction between a polyhydric alcohol and a linear carboxylic acid can be carried out by a known method. For example, a dehydration condensation reaction between the polyhydric alcohol and the linear carboxylic acid can be carried out by heating a mixture of the polyhydric alcohol and the linear carboxylic acid in the presence or absence of a catalyst.
Examples of the catalyst include general acidic or alkaline catalysts used in esterification reactions, and specific examples include zinc acetate, titanium compounds, and the like.
The specific ester wax used in the present disclosure is purified by deacidifying, washing with water, recrystallizing, distilling, etc. the esterified crude product obtained by the condensation reaction of a polyhydric alcohol and a linear carboxylic acid. It may be something like that. Deacidification can be carried out, for example, by mixing the esterified crude product after the condensation reaction with an aqueous alkali solution and, if necessary, an organic solvent, etc., and neutralizing the acid present in the esterified crude product with the alkali. It will be done.

The content of the above-mentioned specific ester wax is not particularly limited, but the lower limit is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and the upper limit is 10 parts by mass or more. is preferably 30 parts by mass or less, more preferably 25 parts by mass or less. The content of the specific ester wax in the toner is preferably 10 parts by mass or more, more preferably 15 parts by mass or more as a lower limit, and preferably 15 parts by mass or more as an upper limit, based on 100 parts by mass of the binder resin. is 30 parts by mass or less, more preferably 25 parts by mass or less.
When the content of the specific ester wax is equal to or higher than the lower limit, it is highly effective in improving the solid followability of the toner. Furthermore, when the content of the specific ester wax is at least the lower limit, deterioration in low-temperature fixability is suppressed, and when the content is at most the upper limit, deterioration in storage stability is suppressed.

As the softener, other softeners different from the above-mentioned specific ester wax may be further contained within a range that does not impair the effects of the present disclosure. Examples of other softeners include those conventionally used as toner softeners or mold release agents, and specifically include low molecular weight polyolefin waxes and modified waxes thereof; petroleum waxes such as paraffin; ozokerite, etc. synthetic waxes such as Fischer-Tropsch wax; and ester waxes with a hydroxyl value of less than 3.0 mgKOH/g.
The content of the other softeners is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 2 parts by mass or less, based on 100 parts by mass of the specific ester wax.

The polymerizable monomer composition contains a positively chargeable or negatively chargeable charge control agent. Thereby, the charging property of the toner can be improved.
The charge control agent is not particularly limited as long as it is generally used as a charge control agent for toners, but among charge control agents, those that have high compatibility with polymerizable monomers and stable chargeability are used. A charge control resin having positive chargeability or negative chargeability is preferable because it can impart (charge stability) to toner particles.

As the positively chargeable or negatively chargeable charge control resin, a functional group-containing copolymer can be used. As the positively chargeable charge control resin, for example, a functional group-containing copolymer containing a structural unit containing a functional group such as an amino group, a quaternary ammonium group, or a quaternary ammonium salt-containing group can be used. , polyamine resins, quaternary ammonium group-containing copolymers, quaternary ammonium base-containing copolymers, and the like. As the negatively chargeable charge control resin, for example, a functional group-containing copolymer containing a structural unit containing a functional group such as a sulfonic acid group, a sulfonate-containing group, a carboxylic acid group, or a carboxylate-containing group is used. Examples thereof include sulfonic acid group-containing copolymers, sulfonic acid group-containing copolymers, carboxylic acid group-containing copolymers, and carboxylic acid group-containing copolymers.
Furthermore, the charge control resin is preferably a styrene acrylic resin because of its high compatibility with the polymerizable monomer. Note that the styrene-acrylic copolymer may be a copolymer of a vinyl aromatic hydrocarbon monomer and a (meth)acrylate monomer. Note that in the present disclosure, (meth)acrylate represents each of acrylate and methacrylate. A (meth)acrylate monomer is a monomer having (meth)acrylate as a polymerizable group.

In the present disclosure, a styrene-acrylic copolymer containing a quaternary ammonium base-containing (meth)acrylate monomer unit is preferably used from the viewpoint of improving image density during printing.
The styrene-acrylic copolymer containing a quaternary ammonium base-containing (meth)acrylate monomer unit contains a quaternary ammonium base-containing (meth)acrylate monomer unit and a vinyl aromatic hydrocarbon monomer unit, Furthermore, it may contain other (meth)acrylate monomer units that do not contain a quaternary ammonium base.
Examples of the quaternary ammonium base-containing (meth)acrylate monomer unit include monomer units represented by the following general formula (I).

In the above general formula (I), R ¹ is a hydrogen atom or a methyl group, R ² is an alkylene group having 1 to 3 carbon atoms which may be substituted with a halogen atom, and R ³ to R ⁵ are: Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and X ^- is a halogen ion, an organic sulfonate ion, or an organic phosphonate ion.

Note that the alkylene group in R ² may be linear or branched, and the alkyl group in R ³ to R ⁵ may be linear, branched, or cyclic.
Examples of the halogen ion in X ⁻ include Cl ⁻ , Br ⁻ , I ⁻ and the like, with Cl ⁻ being preferred. Examples of the organic sulfonate ion include alkylsulfonate ions such as methylsulfonate ion, benzenesulfonate ion, paratoluenesulfonate ion, naphthalenesulfonate ion, and the like. Examples of the organic phosphonate ion include alkylphosphonate ions such as methylphosphonate ion, benzenephosphonate ion, para-toluenephosphonate ion, and the like.

Preferred specific examples of monomers that induce quaternary ammonium group-containing (meth)acrylate monomer units include, for example, N,N,N-trimethyl-N-(2-methacryloxyethyl)ammonium chloride (DMC: N-benzyl-N,N-dimethyl-N-(2-methacryloxyethyl)ammonium chloride (DML; dimethylaminoethylbenzyl methacrylate) and the like can be mentioned. These monomers can be used alone or in combination of two or more.

Monomers for inducing vinyl aromatic hydrocarbon monomer units include, for example, styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethyl Styrene, 4-ethylstyrene, 2-propylstyrene, 3-propylstyrene, 4-propylstyrene, 2-isopropylstyrene, 3-isopropylstyrene, 4-isopropylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chloro Styrene, 2-methyl-α-methylstyrene, 3-methyl-α-methylstyrene, 4-methyl-α-methylstyrene, 2-ethyl-α-methylstyrene, 3-ethyl-α-methylstyrene, 4-ethyl -α-methylstyrene, 2-propyl-α-methylstyrene, 3-propyl-α-methylstyrene, 4-propyl-α-methylstyrene, 2-isopropyl-α-methylstyrene, 3-isopropyl-α-methylstyrene , 4-isopropyl-α-methylstyrene, 2-chloro-α-methylstyrene, 3-chloro-α-methylstyrene, 4-chloro-α-methylstyrene, 2,3-dimethylstyrene, 3,4-dimethylstyrene , 2,4-dimethylstyrene, 2,6-dimethylstyrene, 2,3-diethylstyrene, 3,4-diethylstyrene, 2,4-diethylstyrene, 2,6-diethylstyrene, 2-methyl-3-ethyl Styrene, 2-methyl-4-ethylstyrene, 2-chloro-4-methylstyrene, 2,3-dimethyl-α-methylstyrene, 3,4-dimethyl-α-methylstyrene, 2,4-dimethylstyrene, 2 , 6-dimethyl-α-methylstyrene, 2,3-diethyl-α-methylstyrene, 3,4-diethyl-α-methylstyrene, 2,4-diethyl-α-methylstyrene, 2,6-diethyl-α -methylstyrene, 2-ethyl-3-methyl-α-methylstyrene, 2-methyl-4-propyl-α-methylstyrene, 2-chloro-4-ethyl-α-methylstyrene, and the like. These monomers can be used alone or in combination of two or more.

Examples of monomers for inducing other (meth)acrylate monomer units include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and n-acrylate. - Acrylic acid esters such as amyl, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, hydroxypropyl acrylate, lauryl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, Methacrylic acid esters such as n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, hydroxypropyl methacrylate, lauryl methacrylate; etc. It will be done. These monomers can be used alone or in combination of two or more.

In the styrene-acrylic copolymer containing a quaternary ammonium base-containing (meth)acrylate monomer unit, the lower limit of the copolymerization ratio of the quaternary ammonium base-containing (meth)acrylate monomer is preferably 0.1. % by mass or more, more preferably 0.5% by mass or more, and the upper limit is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, still more preferably 2.0% by mass or less, and more. More preferably, it is 1.5% by mass or less. When the copolymerization ratio is within the above range, the storage stability of the toner can be improved and the occurrence of fogging can be suppressed.

The glass transition temperature (Tg) of the charge control resin is preferably 60 to 90°C, more preferably 65 to 85°C, still more preferably 70 to 80°C. Within the above range, the balance between preservability and fixability is good.

The weight average molecular weight (Mw) of the charge control resin is preferably 8,000 to 28,000, more preferably 10,000 to 25,000, even more preferably 15,000 to 28,000. Preferably, it is 23,000. When the weight average molecular weight (Mw) is at least the above lower limit value, deterioration in storage stability and print durability can be suppressed, and when it is at most the above upper limit value, deterioration in fixability can be suppressed. Furthermore, when the weight average molecular weight (Mw) is within the above range, the charge control resin can be suitably dispersed in the polymerizable monomer composition, so that the toner can be provided with a stable charge amount over time. is easy to obtain.

As the styrene-acrylic copolymer containing a quaternary ammonium base-containing (meth)acrylate monomer unit, various commercially available products can be used. As a commercially available product, for example, FCA-676P (trade name, manufactured by Fujikura Kasei Co., Ltd., Tg: 73°C, weight average molecular weight (Mw) :19,500), FCA-592P (trade name, manufactured by Fujikura Kasei Co., Ltd., Tg: 82°C, weight average molecular weight (Mw): 12,000), etc.

The lower limit of the content of the charge control resin is preferably 4.8 parts by mass or more, more preferably 5.0 parts by mass or more, and the upper limit is preferably It is 15.0 parts by mass or less, more preferably 10.0 parts by mass or less, still more preferably 7.0 parts by mass or less. The content of the charge control resin in the toner is preferably 4.8 parts by mass or more, more preferably 5.0 parts by mass or more as a lower limit, and an upper limit of 100 parts by mass of the binder resin. , preferably 15.0 parts by mass or less, more preferably 10.0 parts by mass or less, still more preferably 7.0 parts by mass or less.
When the content of the charge control resin is within the above range, the amount of blow-off charge of the colored resin particles tends to reach a desired value, and the printing performance tends to improve. Furthermore, when the content of the charge control resin is at least the above lower limit value, fogging can be suppressed, and when the content is at most the above upper limit value, printing stains can be suppressed.

The charge control agent may contain substances other than the charge control resin.
Examples of charge control agents other than positively chargeable charge control resins include nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds, and imidazole compounds.
Examples of the charge control agent other than the negatively chargeable charge control resin include azo dyes containing metals such as Cr, Co, Al, and Fe, metal salicylate compounds, metal alkylsalicylate compounds, and the like.
These charge control agents can be used alone or in combination of two or more.
The content of the charge control agent other than the charge control resin is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less, based on 100 parts by mass of the charge control resin.

In the polymerizable monomer composition, it is preferable to use a molecular weight regulator as another additive when polymerizing the polymerizable monomer.
The molecular weight regulator is not particularly limited as long as it is generally used as a molecular weight regulator for toners, and examples thereof include t-dodecylmercaptan, n-dodecylmercaptan, n-octylmercaptan, and 2,2, Mercaptans such as 4,6,6-pentamethylheptane-4-thiol; tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N,N'-dimethyl-N,N'-diphenylthiuram disulfide, N, Thiuram disulfides such as N'-dioctadecyl-N,N'-diisopropylthiuram disulfide; and the like. These molecular weight regulators may be used alone or in combination of two or more.
The content of the molecular weight regulator is usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the monovinyl monomer.

(A-2) Suspension step to obtain suspension (droplet formation step)
Next, the polymerizable monomer composition is dispersed in an aqueous medium containing a dispersion stabilizer, a polymerization initiator is added, and then droplets of the polymerizable monomer composition are formed. As mentioned above, the polymerization initiator may be added after the polymerizable monomer composition is dispersed into the aqueous medium and before droplet formation; It may also be added to the monomer composition.
The method of forming droplets is not particularly limited, but for example, an (in-line type) emulsifying and dispersing machine (manufactured by Pacific Kiko Co., Ltd., trade name: Milder), a high-speed emulsifying dispersing machine (manufactured by Primix Co., Ltd., trade name: T.K. Homomixer) This is carried out using a device capable of strong stirring such as MARK II type).

As a polymerization initiator, 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 2,2'-azobisisobutyronitrile Azo compounds such as di-t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylbutanoate, t-hexylperoxy-2 -ethyl butanoate, diisopropyl peroxydicarbonate, di-t-butyl peroxyisophthalate, and t-butyl peroxyisobutyrate. Among these, it is preferable to use organic peroxides because they can reduce residual polymerizable monomers and have excellent printing durability. Among organic peroxides, peroxyesters are preferred because they have good initiator efficiency and can reduce residual polymerizable monomers, and non-aromatic peroxyesters, that is, peroxyesters that do not have an aromatic ring. is more preferable.
These polymerization initiators can be used alone or in combination of two or more.

The amount of the polymerization initiator used in the polymerization of the polymerizable monomer composition is preferably 0.1 to 20 parts by mass, more preferably 0.3 parts by mass, based on 100 parts by mass of the monovinyl monomer. The amount is preferably 1 to 15 parts by weight, particularly preferably 1 to 10 parts by weight.

In the present disclosure, an aqueous dispersion medium refers to a medium containing water as a main component.
It is preferable that the aqueous dispersion medium contains a dispersion stabilizer. Examples of dispersion stabilizers include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate, and magnesium carbonate; phosphates such as calcium phosphate; metals such as aluminum oxide and titanium oxide. Oxides; metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; inorganic compounds such as; water-soluble polymers such as polyvinyl alcohol, methyl cellulose, and gelatin; anionic surfactants; Examples include organic compounds such as nonionic surfactants; amphoteric surfactants; The above dispersion stabilizers can be used alone or in combination of two or more.

Among the above-mentioned dispersion stabilizers, inorganic compounds, particularly colloids of sparingly water-soluble metal hydroxides, are preferred. By using an inorganic compound, especially a colloid of a poorly water-soluble metal hydroxide, the particle size distribution of the colored resin particles can be narrowed, and the amount of dispersion stabilizer remaining after washing can be reduced, resulting in an advantageous result. The resulting toner can reproduce images clearly and has excellent environmental stability.
The poorly water-soluble metal hydroxide colloid is, for example, composed of at least one selected from alkali metal hydroxides and alkaline earth metal hydroxides, and water-soluble polyvalent metal salts (alkaline earth metal hydroxides). ) can be prepared by reacting them in an aqueous medium.
Examples of the alkali metal hydroxide salts include lithium hydroxide, sodium hydroxide, potassium hydroxide, and the like. Examples of alkaline earth metal hydroxide salts include barium hydroxide and calcium hydroxide.
The water-soluble polyvalent metal salt may be any water-soluble polyvalent metal salt other than the compounds corresponding to the alkaline earth metal hydroxides, but examples include magnesium chloride, magnesium phosphate, magnesium sulfate, etc. Magnesium metal salts; calcium metal salts such as calcium chloride, calcium nitrate, calcium acetate, calcium sulfate; aluminum metal salts such as aluminum chloride, aluminum sulfate; barium salts such as barium chloride, barium nitrate, barium acetate; zinc chloride, zinc nitrate , zinc salts such as zinc acetate; and the like. Among these, magnesium metal salts, calcium metal salts, and aluminum metal salts are preferred, magnesium metal salts are more preferred, and magnesium chloride is particularly preferred.
The method of reacting at least one selected from the above-mentioned alkali metal hydroxide salts and alkaline earth metal hydroxide salts with the above-mentioned water-soluble polyvalent metal salts in an aqueous medium is not particularly limited. Examples include a method of mixing at least one aqueous solution selected from alkali metal salts and alkaline earth metal hydroxide salts with an aqueous solution of a water-soluble polyvalent metal salt.

The content of the dispersion stabilizer is appropriately adjusted so as to obtain a toner with a desired particle size, and is not particularly limited, but is based on 100 parts by mass of the polymerizable monomer in the polymerizable monomer composition. The amount is preferably 0.5 to 10 parts by weight, more preferably 1.0 to 8.0 parts by weight. When the content of the dispersion stabilizer is at least the above lower limit, the droplets of the polymerizable monomer composition can be sufficiently dispersed so as not to coalesce in the suspension. On the other hand, if the content of the dispersion stabilizer is below the above upper limit, it is possible to prevent the viscosity of the suspension from increasing during granulation and avoid the problem of the suspension clogging the granulator. can.
Further, the content of the dispersion stabilizer is usually 1 to 15 parts by weight, preferably 1 to 8 parts by weight, per 100 parts by weight of the aqueous medium.

(A-3) Polymerization step After forming droplets of the polymerizable monomer composition as in (A-2) above, the polymerizable monomer composition is injected in the presence of a polymerization initiator. Colored resin particles are formed by subjecting the resin to a polymerization reaction. That is, an aqueous dispersion medium in which droplets of the polymerizable monomer composition are dispersed is heated to initiate polymerization and form an aqueous dispersion of colored resin particles.
The heating conditions are not particularly limited, but the heating temperature is preferably 50°C or higher, more preferably 60 to 95°C. Further, the heating time is preferably 1 hour to 20 hours, more preferably 2 hours to 15 hours.

In the present disclosure, although an external additive may be added to the colored resin particles obtained by the above polymerization process and used as a toner, the colored resin particles obtained by the above polymerization process are used in a so-called core shell type (or "capsule type" ) is preferably used as a core layer of colored resin particles. The core-shell type colored resin particles have a structure in which the outside of the core layer is covered with a shell layer formed of a material different from the core layer. By covering the core layer made of a material with a low softening point with a material with a higher softening point, it is possible to improve the low-temperature fixability and storage stability of the toner in a well-balanced manner.

There is no particular restriction on the method for producing core-shell type colored resin particles using the colored resin particles obtained by the above polymerization step, and they can be produced by conventionally known methods. An in situ polymerization method or a phase separation method is preferred from the viewpoint of production efficiency.

A method for producing core-shell colored resin particles using an in situ polymerization method will be described below.
A core-shell type is created by adding a polymerizable monomer for forming a shell layer (polymerizable monomer for shell) and a polymerization initiator to an aqueous dispersion medium in which colored resin particles are dispersed, and polymerizing it. Colored resin particles can be obtained.

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

Polymerization initiators used in the polymerization of the polymerizable monomer for the shell include persulfate metal salts such as potassium persulfate and ammonium persulfate; 2,2'-azobis(2-methyl-N-(2-hydroxyethyl) ) propionamide), and azo-based initiators such as 2,2'-azobis-(2-methyl-N-(1,1-bis(hydroxymethyl)2-hydroxyethyl)propionamide); Polymerization initiators can be mentioned. These can be used alone or in combination of two or more. The amount of the polymerization initiator is preferably 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the polymerizable monomer for shell.

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

(A-4) Washing, filtration, dehydration, and drying process After the polymerization, the aqueous dispersion of colored resin particles is subjected to a series of washing, filtration, dehydration, and drying operations according to a conventional method. It is preferable to repeat the process several times as necessary.

As for the above-mentioned cleaning method, when an inorganic compound is used as a dispersion stabilizer, the dispersion stabilizer can be dissolved in water and removed by adding acid or alkali to the aqueous dispersion of colored resin particles. preferable. When a poorly water-soluble inorganic hydroxide colloid is used as the dispersion stabilizer, it is preferable to add an acid to adjust the pH of the colored resin particle aqueous dispersion to 6.5 or less. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, as well as organic acids such as formic acid and acetic acid, can be used. Sulfuric acid is preferred.

The method of dehydration and filtration is not particularly limited, and various known methods can be used. Examples include centrifugal filtration, vacuum filtration, pressure filtration, and the like. Further, the drying method is not particularly limited, and various methods can be used.

(B) Pulverization method When manufacturing colored resin particles by employing a pulverization method, the following process is performed, for example.
First, the binder resin, colorant, softener, charge control agent, and other additives added as necessary are mixed in a mixer such as a ball mill, V-type mixer, FM mixer (trade name, Nippon Coke (manufactured by Kogyo Co., Ltd.), high-speed dissolver, internal mixer, etc. Next, the mixture obtained above is kneaded while heating using a pressure kneader, a twin-screw extrusion kneader, a roller, or the like. The obtained kneaded material is coarsely pulverized using a pulverizer such as a hammer mill, cutter mill, or roller mill. Furthermore, it is pulverized using a pulverizer such as a jet mill or a high-speed rotary pulverizer to obtain colored resin particles by the pulverization method.

As the binder resin, colorant, softener, and charge control agent used in the pulverization method, those listed in the suspension polymerization method (A) above can be used. Further, the colored resin particles obtained by the pulverization method can also be made into core-shell type colored resin particles by a method such as an in situ polymerization method, like the colored resin particles obtained by the above-mentioned (A) suspension polymerization method.

In the present disclosure, the binder resin contained in the colored resin particles is typically a polymer of the polymerizable monomer, but polyester resins, epoxy resins, etc., which have been widely used as binder resins for toners A small amount of a system resin or an unreacted polymerizable monomer may be included. Among these, the content of the polyester resin contained in 100 parts by mass of the binder resin is preferably 5 parts by mass or less, more preferably 1 part by mass or less, and 0.1 parts by mass or less. is even more preferable, and it is particularly preferable that the polyester resin is not contained. When the content of the polyester resin is equal to or less than the upper limit value, the environmental stability of the toner can be improved, and in particular, changes in the charge of the toner due to changes in humidity can be suppressed.
Further, when the binder resin contains a resin other than the polymer of the polymerizable monomer, the content of the polymer of the polymerizable monomer in 100 parts by mass of the binder resin is 95 parts by mass or more. The content is preferably 97 parts by mass or more, more preferably 99 parts by mass or more, and even more preferably 99 parts by mass or more.

2. Colored Resin Particles Colored resin particles can be obtained by a manufacturing method such as the above-mentioned (A) suspension polymerization method or (B) pulverization method.
The colored resin particles contained in the toner will be described below. Note that the colored resin particles described below include both core-shell type particles and non-core-shell type particles.

The colored resin particles contained in the toner of the present disclosure have a blow-off charge amount of 15 μC/g or more and 60 μC/g or less, as measured by the charge amount measuring method described below. The lower limit of the blow-off charge amount is preferably 20 μC/g or more, more preferably 30 μC/g or more, and the upper limit is preferably 58 μC/g or less, more preferably 56 μC/g or less.
[Charge amount measurement method]
0.25 g of colored resin particles and 9.75 g of a spherical uncoated Mn-Mg-Sr-Fe ferrite carrier with an average particle diameter of 60 μm were placed in a glass container with a volume of 30 cc (inner dimensions: bottom diameter: 30 mm, height: 50 mm). The colored resin particles are placed in a manufactured container and rotated at 160 rpm for 30 minutes using a roller stirrer, and subjected to triboelectric charging treatment in an environment of 23° C. and 50% relative humidity. 0.2 g of the mixture of the above-mentioned ferrite carrier and the above-mentioned ferrite carrier were put into a Faraday cage, and blow-off was performed for 30 seconds at a nitrogen gas pressure of 0.098 MPa using a blow-off powder charge measuring device to determine the blow-off charge amount of the colored resin particles. (μC/g).

Note that the blow-off charge amount (μC/g) of the colored resin particles can be calculated using the following formula (1).
Formula (1)
Blow-off charge amount of colored resin particles (μC/g) = Blow-off charge amount of mixture (μC)/{weight of mixture (0.2 g) x content ratio of colored resin particles in mixture (2.5%)}

As the ferrite carrier used in the above charge amount measuring method, for example, the standard carrier EF-60 (trade name, manufactured by Powder Tech, Mn-Mg-Sr-Fe system, spherical, no resin coating, average particle size 60 μm) can be used.
Further, as the blow-off powder charge amount measuring device used in the charge amount measuring method, for example, a blow-off type Q/M meter MODEL 231 TO (trade name, manufactured by Trek Japan) can be used.

The lower limit of the volume average particle diameter (Dv) of the colored resin particles is preferably 4.0 μm or more, more preferably 5.0 μm or more, even more preferably 6.0 μm or more, and the upper limit is preferably 12.0 μm or more. It is 0 μm or less, more preferably 10.0 μm or less, even more preferably 8.0 μm or less. When the Dv of the colored resin particles is equal to or greater than the above lower limit, the fluidity of the toner can be improved, toner leakage can be suppressed, and deterioration of transferability and decrease in image density can be suppressed. On the other hand, when the Dv of the colored resin particles is equal to or less than the above upper limit value, it is possible to suppress a decrease in image resolution. In particular, when the Dv of the colored resin particles is 6.0 μm or more and 8.0 μm or less, toner leakage from the seal portion between both axial ends of the developing roller and the housing of the developer cartridge is suppressed during durability. Ru.

Further, the ratio of the volume average particle diameter (Dv) to the number average particle diameter (Dn) (Dv/Dn) of the colored resin particles is preferably 1.0 to 1.3, more preferably 1. .0 to 1.2. When Dv/Dn exceeds 1.3, deterioration in transferability, image density and resolution may occur. The volume average particle size and number average particle size of the colored resin particles can be measured using, for example, a particle size analyzer (trade name: Multisizer, manufactured by Beckman Coulter).

From the viewpoint of image reproducibility, the average circularity of the colored resin particles is preferably 0.96 to 1.00, more preferably 0.97 to 1.00, and 0.98 to 1.00. More preferably, it is 00. When the average circularity of the colored resin particles is 0.96 or more, fine line reproducibility of printing can be improved. The average circularity of the colored resin particles of the present disclosure is 1 or less, and when the measurement sample is completely spherical, the average circularity is 1.
In the present disclosure, circularity is a value obtained by dividing the perimeter of a circle having the same projected area as the particle image by the perimeter of the projected image of the particle. The average circularity is an index indicating the degree of unevenness on the surface of a measurement sample, and can be used as a simple method to quantitatively express the shape of particles. The more complex the surface shape of the measurement sample, the smaller the average circularity value.
The circularity of colored resin particles can be measured, for example, by using an aqueous solution in which colored resin particles are dispersed as a sample solution, and using a flow type particle image analyzer (for example, manufactured by CIMEX, product name: FPIA-2100, etc.) in the sample solution. A projected image of the colored resin particles is photographed, and from the projected image, the circumference of a circle equal to the projected area of the particle and the circumference of the projected image of the particle are measured. It can be determined by (perimeter of a circle equal to the projected area)/(perimeter of the projected image of the particle). The average circularity is the average value of the circularity of each colored resin particle contained in the sample liquid.

3. Toner of the Present Disclosure The toner of the present disclosure contains the above colored resin particles and an external additive. By performing an external addition treatment by mixing and stirring the colored resin particles with an external additive, the external additive can be attached to the surface of the colored resin particles to form a one-component toner (developer). Note that the one-component toner may be further mixed and stirred with carrier particles to form a two-component developer.

Examples of external additives include inorganic fine particles such as silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, and cerium oxide; polymethyl methacrylate resin, silicone resin, and melamine resin. Examples include organic fine particles; and the like. Among these, inorganic fine particles are preferred, inorganic fine particles containing at least one selected from silica and titanium oxide are more preferred, and silica fine particles are even more preferred.
These external additives can be used alone or in combination of two or more. Among these, it is preferable to use two or more kinds of silica fine particles having different particle sizes, for example, a combination of silica fine particles having a number average primary particle size of 5 to 25 nm and silica fine particles having a number average primary particle size of 30 to 90 nm. It is preferable to do so.
Furthermore, the inorganic fine particles may be hydrophobically treated. As the hydrophobizing agent, for example, silane coupling agents, silicone oils, fatty acids, fatty acid metal salts, etc. can be used. Among these, silane coupling agents and silicone oils are preferred.

The content of the external additive is usually 0.05 to 6 parts by weight, preferably 0.2 to 5 parts by weight, and more preferably 0.5 to 3 parts by weight based on 100 parts by weight of the colored resin particles. When the content of the external additive is at least the above lower limit, it is possible to suppress the generation of transfer residue, and when the content is at most the above upper limit, it is possible to suppress the generation of fog.

The stirrer that performs the external addition treatment is not particularly limited as long as it is a stirring device that can attach the external additive to the surface of the colored resin particles, and examples include FM mixer (trade name, manufactured by Nippon Coke Industry Co., Ltd.), Super Mixer (:Product name, manufactured by Kawada Seisakusho Co., Ltd.), Q Mixer (:Product name, manufactured by Nippon Coke Industry Co., Ltd.), Mechano Fusion System (:Product name, manufactured by Hosokawa Micron Co., Ltd.), and Mechano Mill (:Product name, manufactured by Okada Seiko Co., Ltd.) ) External addition treatment can be performed using a stirrer capable of mixing and stirring.

The toner of the present disclosure has good solid tracking ability, and after being left in a low temperature, low humidity (L/L) environment of 10° C. and 20% RH for 24 hours, the initial print density is 5% in the same environment. When continuous printing is performed from 1 to 10, and black solid printing (print density 100%) is performed on the 10th sheet, the difference in image density (ΔD) between the leading edge and trailing edge of the solid image is less than 0.30. It is preferably less than 0.20, and more preferably less than 0.20.
Note that the above-mentioned ΔD is obtained by the same method as the evaluation of solid followability in Examples described later.

The toner of the present disclosure suppresses the occurrence of fogging under high temperature and high humidity conditions. The toner of the present disclosure was left in a high temperature/high humidity (H/H) environment with a temperature of 35° C. and a humidity of 80% RH for 24 hours, and then was continuously printed on three sheets at a printing density of 5% in the same environment, and then further The fog value after a printing durability test in which 10,000 sheets are continuously printed is preferably 1.0 or less, more preferably 0.5 or less.
Note that the printing durability test is conducted in the same manner as the HH fog test in Examples described later. The fog value is determined in the same manner as the fog value in Examples described later.

The toner of the present disclosure has good storage stability and suppresses a decrease in blocking temperature (heat resistance temperature). The toner of the present disclosure preferably has a blocking occurrence temperature (heat resistance temperature) of 55°C or higher, more preferably 56°C or higher, and even more preferably 57°C or higher. In the present disclosure, the toner blocking occurrence temperature is defined as the highest temperature at which the mass of toner that aggregates becomes 5% by mass or less of the total amount of toner when the toner is stored at a constant temperature for 8 hours. The blocking occurrence temperature of the toner can be measured by the same method as the measurement of the toner's heat resistance temperature in Examples described later.

The present disclosure will be described in more detail below with reference to Examples and Comparative Examples, but the present disclosure is not limited to these Examples. Note that parts and percentages are based on mass unless otherwise specified.

[Production Example 1: Production of ester wax 1]
10 parts of pentaerythritol and 80 parts of stearic acid were added to a reaction vessel equipped with a thermometer, nitrogen inlet tube, stirrer, Dean-Stark trap, and Dimroth condenser. The amount of carboxy groups in stearic acid (COOH/OH ratio) was 0.96 equivalent per 1 equivalent of hydroxyl group in pentaerythritol. Next, the reaction was carried out at 220° C. under a nitrogen stream at normal pressure for 15 hours while distilling off the water produced by the reaction, to obtain an esterified crude product. 10 parts of toluene and 5 parts of isopropanol were added to this esterified crude product, and 15 parts of a 10% potassium hydroxide aqueous solution was added in an amount equivalent to 1.5 times the acid value of the esterified crude product, and the mixture was heated at 70°C. The mixture was stirred for 30 minutes. The deoxidizing process was completed by leaving the mixture to stand for 30 minutes and removing the aqueous phase. Next, 20 parts of ion-exchanged water was added to the obtained oil phase, and the mixture was stirred at 70° C. for 30 minutes, then left to stand for 30 minutes, and the aqueous phase was removed. Washing with water was repeated four times until the pH of the removed aqueous phase became neutral. After washing with water, the oil phase was depressurized at 180° C. and 1 kPa to remove the solvent and filtered to obtain ester wax 1, which was the final target product.

[Production Examples 2 to 5: Production of ester waxes 2 to 5]
Ester waxes 2 to 5 were obtained in the same manner as in Production Example 1, except that the amounts of pentaerythritol and stearic acid added were changed according to Table 1 below.

The hydroxyl value and acid value of the ester waxes 1 to 5 obtained above were measured in accordance with JIS K 0070. The measurement results are shown in Table 2.

[Example 1]
1. Production of colored resin particles 1-1. Preparation of polymerizable monomer composition for core 74 parts of styrene (ST), 26 parts of n-butyl acrylate (BA), polymethacrylic acid ester macromonomer (trade name: AA-6, manufactured by Toagosei Kagaku Kogyo Co., Ltd., Tg = 94°C), 0.90 parts of divinylbenzene (DVB), and 12 parts of carbon black as a coloring agent using a media-type emulsifying and dispersing machine (trade name: Dyno Mill, manufactured by Shinmaru Enterprises). The mixture was dispersed to obtain a polymerizable monomer mixture. A styrene-acrylic polymer (trade name: Acrybase FCA-676P, Fujikura Kasei Co., Ltd.) having a copolymerization ratio of 1% by mass of acrylate monomer units containing a quaternary ammonium base was added to the mixture obtained by wet pulverization as a charge control resin. ), 20 parts of ester wax 1 obtained in Production Example 1, and 1.0 part of tetraethylthiuram disulfide were added, mixed and dissolved to prepare a polymerizable monomer composition for core. .

1-2. Preparation of aqueous dispersion medium To an aqueous solution of 10.4 parts of magnesium chloride dissolved in 280 parts of ion-exchanged water, an aqueous solution of 7.3 parts of sodium hydroxide dissolved in 50 parts of ion-exchanged water was gradually added under stirring. , a magnesium hydroxide colloidal dispersion was prepared.

1-3. Preparation of Polymerizable Monomer for Shell On the other hand, 2 parts of methyl methacrylate and 130 parts of water were finely dispersed using an ultrasonic emulsifier to prepare an aqueous dispersion of the polymerizable monomer for shell.

1-4. Droplet Formation The above polymerizable monomer composition for core was added to the above magnesium hydroxide colloid dispersion (magnesium hydroxide colloid amount: 5.3 parts), stirred, and t- 6 parts of butyl peroxy-2-ethylhexanoate were added. The dispersion liquid containing the polymerization initiator was dispersed using an in-line emulsifying dispersion machine (trade name: Milder MDN303V, manufactured by Taiheiyo Kiko Co., Ltd.) at a rotation speed of 15,000 rpm to obtain a polymerizable monomer composition for the core. droplets were formed.

1-5. Suspension Polymerization A dispersion containing droplets of the polymerizable monomer composition was placed in a reactor, and the temperature was raised to 90°C to perform a polymerization reaction. After the polymerization conversion rate reaches approximately 100%, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)] is added to the aqueous dispersion of the polymerizable monomer for the shell as a polymerization initiator for the shell. -Propionamide] (trade name: VA-086, manufactured by Wako Pure Chemical Industries, Ltd.) dissolved in 0.1 part was added to the reactor. Next, the temperature was maintained at 95° C. for 4 hours to further continue polymerization, and then the reaction was stopped by cooling with water to obtain an aqueous dispersion of core-shell type colored resin particles.

1-6. Post-treatment step: While stirring the aqueous dispersion of colored resin particles, sulfuric acid was added until the pH became 4.5 or less for acid washing (25°C, 10 minutes), and the colored resin particles were filtered out. , washed with water and filtered the washing water. The electrical conductivity of the filtrate at this time was 20 μS/cm. Furthermore, the colored resin particles after the washing and filtration steps were dehydrated and dried to obtain dried colored resin particles.

2. Production of toner To 100 parts of colored resin particles, 0.6 part of hydrophobically treated silica fine particles with a number average primary particle size of 7 nm and 1 part of hydrophobized silica fine particles with a number average primary particle size of 35 nm were added, and The toner of Example 1 was obtained by mixing using a stirrer (trade name: FM mixer, manufactured by Nippon Coke Co., Ltd.).

[Examples 2 to 5, Comparative Examples 1 to 6]
In Example 1, Example 2 was carried out in the same manner as in Example 1, except that each material added in the above "1-1. Preparation of polymerizable monomer composition for core" was changed according to Table 2. -5 and Comparative Examples 1 to 6 were obtained.
The softener used in Comparative Examples 5 and 6 was ester wax (trade name: WE-6, manufactured by NOF Corporation), and the hydroxyl value was 1.6 mgKOH/g and the acid value was 0.1 mgKOH/g. be.

3. Evaluation of Colored Resin Particles The following measurements were performed on the colored resin particles used in each Example and each Comparative Example.

(1) Volume average particle diameter (Dv)
Approximately 0.1 g of colored resin particles was weighed out, placed in a beaker, and 0.1 mL of a surfactant aqueous solution (manufactured by Fuji Film Corporation, trade name: Drywell) was added as a dispersant. Add another 10 to 30 mL of Isotone II to the beaker, disperse it for 3 minutes with a 20W (Watt) ultrasonic disperser, and then use a particle size analyzer (manufactured by Beckman Coulter, product name: Multisizer). The volume average particle diameter (Dv) of the colored resin particles was measured under the following conditions: aperture diameter: 100 μm, medium: Isoton II, and number of particles measured: 100,000.

(2) Measurement of blow-off charge amount 0.25 g of colored resin particles and a standard carrier ferrite carrier (product name: EF-60, manufactured by Powder Tech, Mn-Mg-Sr-Fe system, spherical, without resin coating, (average particle diameter 60 μm) was placed in a glass container with a volume of 30 cc (inner dimensions: bottom diameter 30 mm, height 50 mm), and was rotated at 160 rpm for 30 minutes using a roller stirrer. Triboelectric charging treatment was performed in an environment of 23° C. and 50% relative humidity. 0.2 g of the mixture of the colored resin particles and ferrite carrier after the triboelectric charging treatment was put into a Faraday cage, and a blow-off powder charge measuring device (trade name: Blow-off type Q/M meter MODEL 231 TO, manufactured by Trek Japan) was placed. was used to blow off the mixture for 30 seconds at a nitrogen gas pressure of 0.098 MPa, and the blow-off charge amount (μC) of the mixture was measured. The blow-off charge amount (μC/g) of the colored resin particles was calculated using the following formula (1).
Formula (1)
Blow-off charge amount of colored resin particles (μC/g) = Blow-off charge amount of mixture (μC)/{weight of mixture (0.2 g) x content ratio of colored resin particles in mixture (2.5%)}

4. Evaluation of Toner The following evaluation was performed on the toner obtained in each Example and each Comparative Example.

(1) Evaluation of solid pattern followability Set printing paper in a commercially available non-magnetic one-component development printer (printing speed: 28 sheets/min), put toner in the developing device, and put it at a low temperature of 10°C and 20% RH. After being left in a low humidity (L/L) environment for 24 hours, continuous printing was performed from the beginning at a printing density of 5% in the same environment. When printing the 10th sheet, perform black solid printing (print density 100%), and use a reflective image densitometer (product name: RD918, manufactured by Macbeth) to measure the image density at the tip 50 mm from the top of the solid image. The image density at the rear end 50 mm from the rear end was measured, and the difference (ΔD) in image density between the front end and the rear end was calculated.

(2) HH fog test Set printing paper in a commercially available non-magnetic one-component development printer (printing speed: 28 sheets/min), put toner in the developing device, and use high temperature and high humidity at a temperature of 35°C and a humidity of 80% RH. After being left in a (H/H) environment for 24 hours, three sheets were continuously printed at a printing density of 5% in the same environment. Thereafter, continuous printing was performed at a printing density of 5% under the same environment. After the 10,000th continuous print, white solid printing (print density 0%) is performed, the white solid printing is stopped midway, and the toner in the non-image area on the photoreceptor after development is removed using adhesive tape (Sumitomo 3M). It was attached to Scotch Mending Tape 810-3-18 (manufactured by Co., Ltd., product name: Scotch Mending Tape 810-3-18). I pasted it onto new printing paper. Next, measure the whiteness (B) of the printing paper to which the adhesive tape has been pasted using a whiteness meter (manufactured by Nippon Denshoku Co., Ltd.), and in the same way, apply only the unused adhesive tape to the printing paper. The whiteness (A) was measured, and the difference in whiteness (BA) was taken as the fog value. The smaller the fog value, the less fog and the better.

(3) Heat-resistant temperature After putting 10 g of toner into a 100 mL polyethylene container and sealing it, the container was submerged in a constant temperature water bath whose temperature was set at a predetermined temperature by changing it from 50° C. for 8 hours. I took it out later. The toner was transferred from the removed container onto a 42-mesh sieve while avoiding vibration as much as possible, and set in a powder measuring machine (manufactured by Hosokawa Micron, trade name: Powder Tester (registered trademark) PT-R). After setting the amplitude of the sieve to 1.0 mm and vibrating the sieve for 30 seconds, the mass of the toner remaining on the sieve was measured, and this was taken as the mass of the aggregated toner.
The maximum temperature at which the mass of the aggregated toner was 0.5 g or less was defined as the heat resistance temperature of the toner. The higher the heat resistance temperature, the less likely the toner will be blocked during storage, and the better the toner will be in storage.

[Consideration]
In the toners of Comparative Examples 1 and 2, the hydroxyl value of the ester wax contained as a softening agent was 7.0 mgKOH/g or more, so the heat resistance temperature was low, which meant that blocking was likely to occur during toner storage, so the storage stability was poor. was inferior to
The toner of Comparative Example 3 had a blow-off charge amount of more than 60 μC/g of the colored resin particles, and therefore had poor solid coverage.
In the toner of Comparative Example 4, the blow-off charge amount of the colored resin particles was less than 15 μC/g, so the fog value in the HH fog test was large, and fog was likely to occur in a high temperature and high humidity environment.
In the toner of Comparative Example 5, the hydroxyl value of the ester wax contained as a softening agent was less than 3.0 mgKOH/g, so the toner had poor solid coverage.
In the toner of Comparative Example 6, the hydroxyl value of the ester wax contained as a softening agent was less than 3.0 mgKOH/g, and the blow-off charge amount of the colored resin particles was more than 60 μC/g. In comparison, the solid tracking performance was even worse.

On the other hand, in the toners of Examples 1 to 5, the blow-off charge amount of the colored resin particles is 15 μC/g or more and 60 μC/g or less, and the softening agent is a condensation product of polyhydric alcohol and linear carboxylic acid. In addition, since it contained an ester wax with a hydroxyl value of 3.0 mgKOH/g or more and less than 7.0 mgKOH/g, it had excellent solid coverage and suppressed fogging under high temperature and high humidity environments. The toner has excellent storage stability because it has a high heat resistance temperature, that is, it is less likely to cause blocking during toner storage. Among them, the toners of Examples 1 to 4 had a relatively high amount of blow-off charge of the colored resin particles, so that the occurrence of fogging in a high-temperature, high-humidity environment was more suppressed.

Claims (5)

A toner containing colored resin particles including a binder resin, a colorant, a softener, and a charge control agent, and an external additive, the toner comprising:
The softener includes an ester wax that is a condensate of a polyhydric alcohol and a linear carboxylic acid and has a hydroxyl value of 3.0 mgKOH/g or more and less than 7.0 mgKOH/g,
A toner, wherein the blow-off charge amount of the colored resin particles measured by the charge amount measuring method described below is 15 μC/g or more and 60 μC/g or less.
[Charge amount measurement method]
0.25 g of colored resin particles and 9.75 g of a spherical uncoated Mn-Mg-Sr-Fe ferrite carrier with an average particle diameter of 60 μm were placed in a glass container with a volume of 30 cc (inner dimensions: bottom diameter: 30 mm, height: 50 mm). The colored resin particles are placed in a manufactured container and rotated at 160 rpm for 30 minutes using a roller stirrer, and subjected to triboelectric charging treatment in an environment of 23° C. and 50% relative humidity. 0.2 g of the mixture of the above-mentioned ferrite carrier and the above-mentioned ferrite carrier were put into a Faraday cage, and blow-off was performed for 30 seconds at a nitrogen gas pressure of 0.098 MPa using a blow-off powder charge measuring device to determine the blow-off charge amount of the colored resin particles. (μC/g). The toner according to claim 1, wherein the ester wax is a condensate of a tetrahydric alcohol and a linear monocarboxylic acid. The toner according to claim 1 or 2, wherein the ester wax has an acid value of 1.0 mgKOH/g or less. The charge control agent includes a styrene-acrylic copolymer containing a (meth)acrylate monomer unit containing a quaternary ammonium base, and the quaternary ammonium base-containing (meth)acrylate monomer in the styrene-acrylic copolymer. The copolymerization ratio of the units is 0.1% by mass or more and 3.0% by mass or less, and the content of the styrene-acrylic copolymer is 4.8 parts by mass or more and 15% by mass based on 100 parts by mass of the binder resin. The toner according to any one of claims 1 to 3, wherein the amount is .0 part by mass or less. The toner according to any one of claims 1 to 4, wherein the volume average particle diameter of the colored resin particles is 6.0 μm or more and 8.0 μm or less.