JP2022086714A - Toner and two-component developer - Google Patents

Abstract

To provide a toner and a two-component developer which are excellent in environmental charge stability and charge stability through a life.SOLUTION: A toner is obtained by attaching an external additive to a surface of toner particles containing an amorphous polyester resin and a wax, in which a content of a tetrahydrofuran-insoluble component in the toner particles is 10 mass% or more and 30 mass% or less. The external additive contains a first external additive and a second external additive. The first external additive is silica fine particles that are obtained by hydrophobing silica derived from a sol-gel method with a hydrophobic treatment agent and have a volume average particle size of 20 nm or more and 50 nm or less. The second external additive is silica fine particles that are obtained by hydrophobing silica derived from a gas-phase method with a hydrophobic treatment agent and have a volume average particle size of 5 nm or more and 15 nm or less. When a content of the first external additive in the toner is represented by A, and a content of the second external additive is represented by B, A/B is more than 0.3 and less than 1.5.SELECTED DRAWING: None

Description

The present invention relates to a toner and a two-component developer.

Toner (toner for static charge image development) used in image forming devices such as copiers, multifunction devices, printers, and facsimile machines using an electrophotographic method usually has an external additive adhered to the surface of toner particles. ing.

In order to improve the environmental charge stability of toner (charge stability in various temperature and humidity environments, especially the effect of suppressing high charge in low humidity environment), in general, as an external additive, conductivity such as titanium oxide particles is used. Add sex material. However, the toner to which titanium oxide particles are added as an external additive has a problem that the chargeability decreases as the product life (hereinafter, also referred to as life) approaches after repeated use.

Further, the developer containing the toner to which titanium oxide particles are added as an external additive and the carrier can improve the environmental charge stability and obtain a good developing state, while the cumulative number of printed sheets of the copying machine increases. There is a problem that the stability of environmental charge decreases as a result. This is due to the process of stirring and triboelectricizing the developer under pressure in the developing tank, which causes the external additive to be embedded in the toner particles and the carrier to be contaminated with the external additive, resulting in an environment. It is considered that this is because the charge stability is lowered.

In particular, the effect of carrier contamination by titanium oxide particles is large, and the environmental charge stability of the developer is greatly reduced near the product life of the developer. In some cases, toner and carriers to which titanium oxide particles are not added as an external additive are used. Environmental charge stability may deteriorate to the same extent as the constituent developer.

In Patent Document 1, the number average primary particle diameter, the ratio between the minimum particle diameter and the number average primary particle diameter, and the ratio between the maximum particle diameter and the number average primary particle diameter are within specific ranges. In the static charge image development toner in which the silica fine particles produced by the method are monodispersed on the surface of the toner matrix particles as an external additive, the external additive is embedded in the toner matrix particle surface and from the toner matrix particle surface. It is disclosed that both withdrawal and withdrawal are suppressed.

Patent Document 2 describes a toner containing a crystalline polyester resin produced by an ester extension polymerization method, and a dry type with silica derived from a sol-gel method having an average primary particle size within a specific range on the surface of the toner matrix particles. Toner that has silica derived from the method, has a coverage within a specific range, and absorbs moisture by a specific amount or more when the silica derived from the sol-gel method is left for one week under specific conditions is a toner under high temperature and high humidity. It is disclosed that aggregation can be suppressed.

Japanese Unexamined Patent Publication No. 2011-43759 Japanese Unexamined Patent Publication No. 2012-189876

However, there is a problem that the local charge-up in a low humidity environment cannot be suppressed and the environmental charge stability is insufficient only by the composition of the toner external additive described in Patent Document 1. Since the toner described in 1 is a toner produced by an ester extension polymerization method, the crystalline polyester resin exists in the toner matrix particles without being incompatible with the surroundings while maintaining the crystallinity, and the skeleton is hard. There is a problem that the charge does not easily leak in a low temperature environment and causes a charge-up. Further, since the toner described in Patent Document 2 contains titanium oxide as an external additive, it is considered that the charge stability throughout the life is insufficient.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a toner and a two-component developer having excellent environmental charge stability and charge stability throughout life. ..

The invention made to solve the above-mentioned problems is a toner in which an external additive is attached to the surface of toner particles containing an amorphous polyester resin and wax, and the tetrahydrofuran (THF) insoluble content in the toner particles. The content is 10% by mass or more and 30% by mass or less, the external additive contains a first external particle and a second external additive, and the first external agent is hydrophobic with silica derived from the Zolgel method. The second external additive is silica fine particles having a volume average particle diameter of 20 nm or more and 50 nm or less, which is hydrophobicized by the chemical treatment agent, and the silica derived from the vapor phase method is made hydrophobic by the hydrophobic treatment agent. Assuming that the silica fine particles have a volume average particle diameter of 5 nm or more and 15 nm or less, the content of the first external additive in the toner is A, and the content of the second external additive is B, the A / B is 0.3. It is characterized by being less than super 1.5.

According to the above invention, it is possible to realize a toner having excellent environmental charge stability and charge stability throughout life.

In the above toner, the wax is an ester wax, and the heat absorption peak temperature at the time of temperature rise derived from the wax, which is measured by using a differential scanning calorimeter, is T1, and the heat generation peak at the time of cooling derived from the wax. When the temperature is T2, T1-T2 is preferably 15 ° C. or higher and 30 ° C. or lower.

By satisfying such a condition for the wax, it is possible to prevent the chargeability from deteriorating as the cumulative number of printed sheets increases. The reason for this is thought to be as follows.

In the wax satisfying the above conditions, the affinity between the wax and the amorphous polyester resin is improved and the wax dispersion diameter is reduced. In addition, the effect of wax as an internal lubricant (the effect of exerting a lubricating action inside the material during melt-kneading to disperse the material) becomes greater, and THF insoluble content (high elasticity component, gel content) is contained in the toner particles. Even if it is contained in a large amount, the highly elastic component can be sufficiently finely dispersed. By reducing the wax dispersion diameter, the wax area exposed on the surface of the toner particles (toner matrix particles) is reduced, and the highly elastic component in the toner particles is sufficiently finely dispersed to make the surface hardness of the toner particles uniform. Since the state can be set to a moderately high level, it is possible to suppress the embedding of the external additive on the surface of the toner particles and to prevent the chargeability from deteriorating as the cumulative number of printed sheets increases.

In the above toner, the toner particles contain a styrene acrylic resin, and the content of the styrene acrylic resin in the toner particles is preferably 1% by mass or more and 10% by mass or less.

By containing the styrene acrylic resin, which has a higher affinity for wax than the amorphous polyester resin, in the above content, the exposure of the wax to the surface of the toner particles can be further suppressed, and the toner particles of the external additive can be used throughout the life. Since it is possible to suppress the burial in the toner, it is possible to further suppress the deterioration of the chargeability as the cumulative number of printed sheets increases.

In the above toner, the first external additive is silica fine particles hydrophobicized with hexamethyldisilazane (HMDS), and the second external additive is hydrophobicized with dimethyldichlorosilane (DDS). It is preferably silica fine particles. Further, assuming that the content of the first external additive in the toner is A and the content of the second external additive is B, the A / B is more preferably more than 0.7 and less than 1.3.

When the external additive satisfies such a condition, it is possible to prevent the chargeability from deteriorating as the cumulative number of printed sheets increases. The reason for this is thought to be as follows.

By applying HMDS treatment to silica fine particles having a large particle size and DDS treatment to silica fine particles having a small particle size, toner between silica fine particles having different particle sizes (between the first external additive and the second external additive) The difference in fluidity on the particle surface becomes small, and the movement of silica fine particles (first external additive) having a large particle size is suppressed. As a result, it is possible to prevent the chargeability from deteriorating as the cumulative number of printed sheets increases. Further, by setting the mass ratio of the first external additive and the second external additive within the above range, the desorption of silica fine particles and the transfer to carriers can be further suppressed, so that the charge increases as the cumulative number of printed sheets increases. It is possible to further suppress the deterioration of the sex.

In the above toner, the peak top molecular weight of the tetrahydrofuran-soluble component in the toner particles measured by gel permeation chromatography is preferably 4000 or more and 6500 or less.

When the peak top molecular weight of the tetrahydrofuran-soluble component in the toner particles is within the above range, a component having a low viscosity and a low molecular weight is present in the toner particles, so that the component is sufficiently compatible with the highly elastic component and has a high molecular weight. Charge transfer with the elastic component can be performed more smoothly, and charge-up in a low humidity environment can be further suppressed.

Another invention made to solve the above-mentioned problems is a two-component developer containing the above-mentioned toner and a carrier, and the carrier is an iron powder carrier.

Iron powder carriers have much lower resistance than commonly used ferrite carriers. Therefore, the transfer of electric charge to and from the toner becomes faster, the charge rises quickly, the charging characteristics are excellent even in a high-humidity environment, and it also becomes a leak point in a low-humidity environment. The agent can be realized.

According to the present invention, it is possible to provide a toner and a two-component developer having excellent environmental charge stability and charge stability throughout life.

The present invention includes a toner and a two-component developer. Hereinafter, these will be described in detail.

[Toner, toner particles]
The toner of the present invention is a toner in which an external additive is attached to the surface of toner particles containing an amorphous polyester resin and wax. Further, if necessary, any component may be contained as long as the effect of the present invention is not impaired. The volume average particle diameter of the primary particles of the toner particles is not particularly limited, and examples thereof include toner particles having a volume average particle diameter of 4 μm or more and 8 μm or less.

In the present invention, the amorphous resin and the crystalline resin are distinguished by a crystallinity index, and a resin having a crystallinity index in the range of 0.6 or more and 1.5 or less is defined as a crystallinity resin and has a crystallinity index. A resin having a value of less than 0.6 or more than 1.5 is defined as an amorphous resin. A resin having a crystallinity index of more than 1.5 is amorphous, and a resin having a crystallinity index of less than 0.6 has low crystallinity and many amorphous portions.

The crystallinity index is a physical property that is an index of the degree of crystallization of the resin, and is defined by the ratio of the softening temperature to the maximum peak temperature of heat absorption (softening temperature / maximum peak temperature of heat absorption). Here, the maximum endothermic temperature refers to the temperature of the peak on the highest temperature side among the observed endothermic peaks. In the crystalline polyester resin, the maximum peak temperature is set as the melting point, and in the amorphous polyester resin, the peak on the highest temperature side is set as the glass transition point.

The degree of crystallization can be controlled by adjusting the type and ratio of the raw material monomer, the production conditions (for example, reaction temperature, reaction time, cooling rate) and the like.

<Amorphous polyester resin>
The toner particles according to the present invention contain an amorphous polyester resin as a binder resin. As long as the effect of the present invention is not impaired, the binder resin may contain a component other than the amorphous polyester resin.

The amorphous polyester resin used for the toner of the present invention is an amorphous polyester resin obtained by polycondensing a dicarboxylic acid monomer containing terephthalic acid or isophthalic acid as a main component and a diol monomer containing ethylene glycol as a main component. Is.

The dicarboxylic acid monomer used in the synthesis of the amorphous polyester resin contains terephthalic acid or isophthalic acid as a main component. Here, the molar content of terephthalic acid or isophthalic acid in the dicarboxylic acid monomer is preferably 70% or more and 100% or less, and more preferably 80% or more and 100% or less.

Further, the dicarboxylic acid monomer can contain aromatic dicarboxylic acids and aliphatic dicarboxylic acids other than terephthalic acid and isophthalic acid. Examples of aromatic dicarboxylic acids other than terephthalic acid and isophthalic acid include fumaric acid, and examples of aliphatic dicarboxylic acids include adipic acid, sebacic acid, and succinic acid. The dicarboxylic acid monomer can also include an ester-forming derivative of terephthalic acid or isophthalic acid, an ester-forming derivative of aromatic dicarboxylic acid other than terephthalic acid and isophthalic acid, and an ester-forming derivative of an aliphatic dicarboxylic acid. In the present invention, the ester-forming derivative includes an acid anhydride of a carboxylic acid, an alkyl ester and the like. When a dicarboxylic acid monomer other than terephthalic acid and isophthalic acid is used, the dicarboxylic acid monomer may be used alone or in combination of two or more.

In the synthesis of the amorphous polyester resin, a polycarboxylic acid monomer having a valence of 3 or more may be used together with the dicarboxylic acid monomer. As the trivalent or higher valent polycarboxylic acid monomer, trimellitic acid, pyromellitic acid and other trivalent or higher polycarboxylic acids and ester-forming derivatives thereof can be used. When a polycarboxylic acid monomer having a valence of 3 or more is used, the polycarboxylic acid monomer may be used alone or in combination of two or more.

The diol monomer used in the synthesis of the amorphous polyester resin contains ethylene glycol as a main component. Here, the molar content of ethylene glycol in the diol monomer is preferably 70% or more and 100% or less, and more preferably 80% or more and 100% or less.

Further, the diol monomer may contain 1,3-propylene glycol, 1,4-butanediol and the like. When a diol monomer other than ethylene glycol is used, the diol monomer may be used alone or in combination of two or more.

The amorphous polyester resin used for the toner of the present invention can be produced in the same manner as a normal polyester production method. For example, a polycondensation reaction is carried out at a temperature of 190 to 240 ° C. in a nitrogen gas atmosphere using a dicarboxylic acid monomer, a diol monomer and, in some cases, a polycarboxylic acid monomer having a valence of 3 or more, thereby making it amorphous. Polyester resin can be synthesized.

In the polycondensation reaction, the reaction ratio of the diol monomer to the carboxylic acid monomer (including the dicarboxylic acid monomer and, in some cases, the polycarboxylic acid monomer having a valence of 3 or more) is the equivalent ratio of the hydroxyl group to the carboxyl group [OH] :. The [COOH] is preferably 1.3: 1 to 1: 1.2. Further, in the polycondensation reaction, the molar content of the dicarboxylic acid monomer in the carboxylic acid monomer is preferably 80 to 100%. Further, in the polycondensation reaction, an esterification catalyst such as dibutyltin oxide or titanium alkoxide (for example, tetrabutoxytitanate) can be used if necessary.

In the toner of the present invention, the content of the amorphous polyester resin is not particularly limited, but is preferably 60% by mass or more and 95% by mass or less in the toner particles.

<THF insoluble content>
The content of the insoluble content of tetrahydrofuran (THF) in the toner particles according to the present invention is 10% by mass or more and 30% by mass or less. A more preferable range is 15% by mass or more and 20% by mass or less. By containing the THF insoluble component (high elasticity component) in the above range in the toner particles, the high temperature side of the fixable region can be expanded.

<Tetrahydrofuran soluble content>
The peak top molecular weight of the tetrahydrofuran-soluble component in the toner particles according to the present invention, which is measured by gel permeation chromatography (GPC), is preferably 4000 or more and 6500 or less. When the peak top molecular weight of the tetrahydrofuran-soluble component in the toner particles is within the above range, a component having a low viscosity and a low molecular weight is present in the toner particles, so that the component is sufficiently compatible with the highly elastic component and has a high molecular weight. Charge transfer with the elastic component can be performed more smoothly, and charge-up in a low humidity environment can be further suppressed.

<Wax>
The toner particles according to the present invention contain wax as a mold release agent. Ester wax is preferable as the wax, and T1 is assumed to be T1 as the heat absorption peak temperature at the time of temperature rise derived from the ester wax and T2 as the exothermic peak temperature at the time of cooling derived from the ester wax as measured by using a differential scanning calorimeter. -T2 is preferably 15 ° C. or higher and 30 ° C. or lower. A more preferable range is 17 ° C. or higher and 23 ° C. or lower. Ester waxes in which T1-T2 satisfy the above conditions have a high inward slip effect (effect of increasing material compatibility during melt-kneading). It should be noted that such ester wax is not usually used for toner applications.

As described above, the inclusion of a highly elastic component (THF insoluble component) in the toner particles greatly improves the fixability in the high temperature range, while the highly elastic component has a very high molecular weight, so that it is difficult for the electric resistance to leak. , Local charge-up in a low humidity environment becomes an issue. Further, since a conductive agent (for example, carbon black) does not enter into the highly elastic component, it is difficult to solve the problem with an external additive. Therefore, by blending the ester wax satisfying the above conditions of T1-T2 into the toner particles, local charge-up can be suppressed even in a low humidity environment, and the embedding of the external additive can be suppressed throughout the life. .. That is, it is possible to realize a toner having excellent environmental charge stability and charge stability throughout life. The reason for this is considered as follows.

The ester wax satisfying the above conditions of T1-T2 has a very high inward slip effect, and by blending the ester wax, the highly elastic component is sufficiently finely dispersed and the viscosity in the binder resin is relatively low. Partially compatible with components and the like. Therefore, a charge leak point can be formed, and charge exchange can be smoothly performed in the toner particles. Therefore, local charge-up can be suppressed even in a low humidity environment. Further, by uniformly finely dispersing the highly elastic component, the hardness of the surface of the toner particles (toner matrix particles) can be kept uniformly high, and the embedding of the external additive can be suppressed throughout the life.

Examples of the ester wax having T1-T2 of 15 ° C. or higher and 30 ° C. or lower include product names WE-14, WE-15, WEP-5 manufactured by NOF CORPORATION.

The content of the ester wax in the toner particles according to the present invention is preferably 0.5% by mass or more and 5% by mass or less, and more preferably 2% by mass or more and 4% by mass or less.

<Styrene acrylic resin>
The toner particles according to the present invention preferably contain a styrene acrylic resin as a release agent dispersant. The content of the styrene acrylic resin in the toner particles is preferably 1% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 8% by mass or less.

By containing the styrene acrylic resin, which has a higher affinity for wax than the amorphous polyester resin, in the above content, the exposure of the wax to the surface of the toner particles can be further suppressed, and the toner particles of the external additive can be used throughout the life. Since it is possible to suppress the burial in the toner, it is possible to further suppress the deterioration of the chargeability as the cumulative number of printed sheets increases.

The styrene acrylic resin is not particularly limited, and those usually used in the technical field to which the present invention belongs can be used. For example, one or more of the following monomers can be polymerized by a known polymerization reaction. Resin is mentioned. Examples of the monomer constituting the styrene acrylic resin include, for example.
Styrene derivatives such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene;
Acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, octyl acrylate, 2-chlorethyl acrylate, phenylacrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, Acrylic acid derivatives and methacrylic acid derivatives such as propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, dimethylaminoester methacrylate;
Can be mentioned. The above-mentioned monomer may be partially modified.

<Other internal additives>
The toner particles according to the present invention may contain an additive other than the above, if necessary. Examples of the internal additive other than the above include a colorant and a charge control agent. The colorant and the charge control agent are dispersed in the binder resin.

The colorant is not particularly limited, and organic dyes, organic pigments, inorganic dyes, inorganic pigments and the like used in the field of electrophotographic can be used.

As the black colorant, for example, carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, non-magnetic ferrite, magnetic ferrite and magnetite can be used.

Examples of the yellow colorant include C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 138, C.I. I. Pigment Yellow 180, C.I. I. Pigment Yellow 185 can be used.

Examples of the magenta colorant include C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 222 can be used.

Examples of the cyan colorant include C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60 can be used.

In the toner of the present invention, the content of the colorant is not particularly limited, but it is preferably 4% by mass or more and 10% by mass or less in the toner particles. As the colorant, one kind may be used alone, or two or more kinds may be used in combination. The colorant may be used as a masterbatch in order to be uniformly dispersed in the binder resin.

The charge control agent is added to impart favorable chargeability to the toner. The charge control agent is not particularly limited, and charge control agents for positive charge control and negative charge control used in the electrophotographic field can be used.

As the charge control agent for positive charge control, for example, a quaternary ammonium salt, a pyrimidine compound, a triphenylmethane derivative, a guanidine salt, or an amidine salt can be used.

Examples of the charge control agent for negative charge control include metal-containing azo compounds, azo complex dyes, metal complexes and metal salts of salicylic acid and its derivatives (metals are chromium, zinc, zirconium, etc.), organic bentonite compounds, and boron compounds. Can be used.

In the toner of the present invention, the content of the charge control agent is not particularly limited, but is preferably 0.5% by mass or more and 5% by mass or less in the toner particles. The charge control agent may be used alone or in combination of two or more.

<External agent>
In the present invention, the external additive includes a first external additive and a second external additive. As long as the effect of the present invention is not impaired, components other than the first external additive and the second external additive may be contained.

The first external additive is silica fine particles having a volume average particle diameter of 20 nm or more and 50 nm or less, in which silica derived from the sol-gel method is hydrophobized by a hydrophobizing treatment agent. Silica produced by the sol-gel method has the characteristics of high water content and volume resistance, a sharp particle size distribution, and excellent water adsorption. A more preferable range of the volume average particle diameter is 25 nm or more and 35 nm or less.

The second external additive is silica fine particles having a volume average particle diameter of 5 nm or more and 15 nm or less, in which silica derived from the vapor phase method is hydrophobicized by a hydrophobic treatment agent. Silica produced by the vapor phase method has a relatively broad particle size distribution, but has a very small amount of water and a strong negative charge, so that it has a high charging capacity. A more preferable range of the volume average particle diameter is 5 nm or more and 9 nm or less.

When the content of the first external additive in the toner of the present invention is A and the content of the second external additive is B, the A / B is more than 0.3 and less than 1.5. By adding the above two types of silica fine particles so that the content is within the above range, the environmental charge stability as a toner is enhanced, and the transfer of the external additive to the carrier and the toner particles (toner matrix particles) are enhanced. ) Can be suppressed from being buried in the external additive. In addition to this, as described above, the highly elastic component is uniformly finely dispersed in the toner particles, so that the silica fine particles have a very small particle size like the volume average particle size of the second external additive. Even if there is, it is possible to suppress the embedding in the toner particles (toner matrix particles) and maintain the charge throughout the life (excellent charge stability throughout the life).

In this way, by configuring both the toner particles and the external additive to suppress local charge-up in a low humidity environment, charge exchange between the toner particles and the external additive becomes smooth and the humidity is low. The charge-up in the environment can be further suppressed, and the charge-up characteristics in a high-humidity environment can be improved by improving the charge-up characteristics, so that the environmental charge stability as a toner can be improved.

Further, it is preferable that the first external additive is silica fine particles hydrophobicized with hexamethyldisilazane (HMDS), and the second external additive is silica fine particles hydrophobicized with dimethyldichlorosilane (DDS).

By applying HMDS treatment to silica fine particles having a large particle size and DDS treatment to silica fine particles having a small particle size, toner between silica fine particles having different particle sizes (between the first external additive and the second external additive) The difference in fluidity on the particle surface becomes small, and the movement of silica fine particles (first external additive) having a large particle size is suppressed. As a result, it is possible to prevent the chargeability from deteriorating as the cumulative number of printed sheets increases.

When the first external additive is silica fine particles hydrophobicized by HMDS and the second external additive is silica fine particles hydrophobicized by DDS, the content of the first external additive in the toner is A, first. 2 Assuming that the content of the external additive is B, the A / B is more preferably more than 0.7 and less than 1.3.

When the content ratio is within the above range, the desorption of silica fine particles and the transfer to carriers can be further suppressed, so that deterioration of chargeability can be further suppressed as the cumulative number of printed sheets increases.

<Two-component developer>
The two-component developer of the present invention includes the toner and the carrier according to the present invention. The two-component developer can be produced by mixing the toner and the carrier using a known mixer. The mass ratio of the toner to the carrier is not particularly limited, and examples thereof include 3:97 to 12:88.

The carriers are agitated and mixed with the toner in the developing tank to give the toner the desired charge. Further, the carrier acts as an electrode between the developing device and the photoconductor, carries the charged toner to the electrostatic latent image on the photoconductor, and plays a role of forming the toner image. The carrier is held on the developing roller of the developing apparatus by magnetic force, acts on the developing, then returns to the developing tank again, is stirred and mixed again with new toner, and is used repeatedly until the end of its life.

The carrier in the two-component developer of the present invention is an iron powder carrier having an iron powder carrier core material and a resin coating layer covering the iron powder carrier core material.

Since the iron powder carrier has a very low resistance as compared with the commonly used ferrite carrier, it is possible to transfer and transfer charges to and from the toner more quickly. Therefore, the charging rises quickly and the charging characteristics are excellent even in a high-humidity environment, and it also becomes a leak point in a low-humidity environment. Therefore, by using an iron powder carrier as the carrier, it is possible to provide a two-component developer having better environmental charge stability.

Examples of the volume average particle diameter of the carrier core material include 30 μm and more and 100 μm or less. The resin coating layer preferably contains a silicone resin or an acrylic resin. Silicone resin can delay the progress of contamination of the carrier coat layer and is suitable for long-life use.

Hereinafter, the present invention will be described based on Examples and Comparative Examples, but the present invention is not limited to these Examples. First, the measurement method performed in Examples and Comparative Examples will be described.

<Measurement method of endothermic peak temperature at the time of temperature rise and heat generation peak temperature at the time of cooling>
Using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.), heat 1 g of the sample to 150 ° C at a heating rate of 10 ° C per minute, hold it at 150 ° C for 2 minutes, and cool it. The DSC curve was measured at a speed of 10 ° C. per minute, cooled to 30 ° C. The endothermic peak temperature at the time of raising the temperature and the exothermic peak temperature at the time of cooling of the obtained DSC curve were obtained.

<Measurement method of peak top molecular weight (Mp)>
The peak top molecular weight (Mp) of the binder resin and the toner was measured by gel permeation chromatography (GPC) under the following conditions. In addition, for the measurement of the molecular weight, a polyester resin dissolved in THF and the insoluble component filtered by a glass filter was used as a sample solution. The peak top molecular weight refers to the molecular weight showing the maximum peak height in the chromatogram obtained by GPC measurement.
・ Equipment: HLC-8120 manufactured by Tosoh Corporation
-Column: 2 TSK GEL GMH6 [manufactured by Tosoh Corporation]
・ Measurement temperature: 40 ° C
-Sample solution: 0.25% by mass of THF (tetrahydrofuran) solution-Solution injection amount: 100 μl
・ Detection device: Refractive index detector ・ Reference material: Tosoh standard polystyrene (TSKstandard POLYSTYRENE) 12 points (molecular weight 500 1050 2800 5970 9100 18100 37900 96400 1900000 355000 1090000 2890000)

<Method of measuring the content of THF insoluble (gel) in toner>
It was calculated from the amount of THF insoluble before and after the above GPC measurement.

<Measuring method of toner volume average particle size>
To 50 ml of an electrolytic solution (trade name: ISOTON-II, manufactured by Beckman Coulter Co., Ltd.), add 20 mg of toner and 1 ml of alkyl ether sulfate ester sodium, and add an ultrasonic disperser (trade name: UH-50, manufactured by SMT Co., Ltd.). Using, dispersion treatment was performed at an ultrasonic frequency of 20 kHz for 3 minutes to prepare a sample for measurement. This measurement sample was measured using a particle size distribution measuring device (trade name: Coulter Multisizer II, manufactured by Beckman Coulter Co., Ltd.) under the conditions of an aperture diameter of 100 μm and a measurement particle count of 50,000 counts, and the volume of the sample particles was measured. The volume average particle size of the toner was obtained from the particle size distribution.

<Calculation method of SP value>
The SP value was calculated by the method described in "POLYMER ENGINEERING AND SCIENCE, FEBRUARY, 1974, Vol. 14, No. 2, ROBERT F. FEDORS." Proposed by Fedors et al.

<Measurement method of resin outflow start temperature and softening temperature>
Using a flow property evaluation device (manufactured by Shimadzu Corporation, flow tester, model number: CFT-100C), a load of 20 kgf / cm ² is used while heating 1 g of the sample from the starting temperature of 40 ° C. at a heating rate of 6 ° C./min. (9.8 × 105 Pa) was given, and the sample was discharged from the die (nozzle diameter 1 mm, length 1 mm). The temperature at which the sample began to flow out was defined as the outflow start temperature "Ti", and the temperature at which half of the sample flowed out was defined as the softening temperature "Tm".

<Evaluation method of environmental charge stability>
The prepared two-component developer and toner are filled in the developing device and toner cartridge of a color multifunction device (trade name: MX-2640, manufactured by Sharp Corporation), respectively, and the center and both ends in the axial direction of the developing roller are 3 respectively. A continuous print test of 50,000 sheets was performed in an environment of a temperature of 25 ° C. and a humidity of 50% so that a solid image (ID = 1.45 to 1.50) having a side of 1 cm was formed at the positions of the dots. Before and after that, the evaluator was left in an environment with a temperature of 25 ° C and a humidity of 5% and an environment with a temperature of 25 ° C and a humidity of 80% for 2 days to adjust the humidity, and then a suction type charge measuring device (manufactured by Trek Co., Ltd., model: Model210HS). The charge amount (μC / g) of the two-component developer in each environment was measured, and the environmental charge stability was evaluated from the absolute value of the difference in the charge amount in each environment according to the following criteria.

⊚: Excellent (difference in charge amount in each environment is 5 μC / g or less)
◯: Good (difference in charge amount in each environment is more than 5 μC / g and less than 10 μC / g)
Δ: Possible (difference in charge amount in each environment is more than 10 μC / g, 15 μC / g or less)
×: Defective (difference in charge amount in each environment exceeds 15 μC / g)

<Evaluation method of charge stability throughout life>
The prepared two-component developer and toner are filled in the developing device and toner cartridge of a color multifunction device (trade name: MX-2640, manufactured by Sharp Corporation), respectively, and the center and both ends in the axial direction of the developing roller are 3 respectively. A continuous print test of 50,000 sheets was performed in an environment of a temperature of 25 ° C. and a humidity of 50% so that a solid image (ID = 1.45 to 1.50) having a side of 1 cm was formed at the positions of the dots. Before and after that, the charge amount (μC / g) of the two-component developer was measured using a suction type charge amount measuring device (manufactured by Trek Co., Ltd., model: Model210HS), and from the absolute value of the difference, the following The amount of charge was evaluated as a standard.

<Comprehensive evaluation method for toner and two-component developer>
Based on the above evaluation results (three items: evaluation before continuous print test of environmental charge stability, evaluation after continuous print test of environmental charge stability, evaluation of charge stability throughout life), comprehensively based on the following criteria Evaluation was performed.

◎: Excellent: ◎ in all evaluation items.
◯: Good: The lowest evaluation of the three items is ◯.
Δ: Possible: The lowest evaluation among the three items is Δ.
×: Impossible: The lowest evaluation among the three items is ×.

Next, a process for producing the toner and the two-component developer such as Examples will be described.

<Preparation of external additive>
Used to prepare silica fine particles (A-1) to (A-5) as the first external additive and silica fine particles (B-1) to (B-5) as the second external additive. A list of silica fine particles as materials and a hydrophobic treatment agent used for surface treatment is shown in Table 1 below.

Regarding the silica fine particles other than (A-3) in Table 1, the product itself is in a state of being surface-treated with the hydrophobic treatment agent shown in Table 1, while the column of silica fine particles in (A-3) shows. Since the product shown is not surface-treated with oil, silica fine particles (A-3) were prepared by the following procedure.

(Preparation of silica fine particles (A-3) hydrophobized by oil)
Add 30 parts by mass of silicone oil (trade name: KF 96 50cs, manufactured by Shin-Etsu Chemical Co., Ltd.) to 100 parts by mass of silica fine particles (trade name: Scicas Series, manufactured by Sakai Chemical Industry Co., Ltd.) while stirring in a nitrogen atmosphere. A solution diluted with 25 parts by weight of hexane was sprayed. The reaction mixture was stirred at 300 ° C. for 60 minutes with a nitrogen stream to dry, and then cooled to prepare silica fine particles (A-3).

<Creation of carrier>
(Preparation of carrier (1) (iron powder carrier))
Coated resin (1) (silicone type, trade name: KR240, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.375 parts by mass, and coated resin (2) (trade name: KR251, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.375 mass Parts are dissolved in 12 parts by mass of toluene, and 0.0375 parts by mass of conductive particles (trade name: VULCAN XC-72, manufactured by Cabot Co., Ltd.) and a coupling agent (trade name: AY43-059, Toray Dow) are dissolved therein. (Manufactured by Corning Co., Ltd.) 0.0225 parts by mass was added and dispersed to prepare a coated resin solution. By the dipping method, the surface of 100 parts by mass of the iron powder carrier core material having a volume average particle diameter of 60 μm was covered with 12.8 parts by mass of the coating resin liquid. Then, after undergoing a curing process at a cure temperature of 200 ° C. and a cure time of 1 hour, an iron powder carrier (carrier (1)) was prepared by sieving with a mesh opening of 150 μm.

(Manufacturing of carrier (2) (ferrite carrier))
Coated resin (1) (silicone type, trade name: KR240, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.375 parts by mass, and coated resin (2) (trade name: KR251, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.375 mass Parts are dissolved in 12 parts by mass of toluene, and 0.0375 parts by mass of conductive particles (trade name: VULCAN XC-72, manufactured by Cabot Co., Ltd.) and a coupling agent (trade name: AY43-059, Toray Dow) are dissolved therein. (Manufactured by Corning Co., Ltd.) 0.0225 parts by mass was added and dispersed to prepare a coated resin solution. By the dipping method, the surface of 100 parts by mass of the ferrite carrier core material having a volume average particle diameter of 40 μm was covered with 12.8 parts by mass of the coating resin liquid. Then, after undergoing a curing process at a cure temperature of 200 ° C. and a cure time of 1 hour, a ferrite carrier (carrier (2)) was prepared by sieving with a mesh opening of 150 μm.

<Manufacturing toner and two-component developer>
[Example 1]
(Material mixing / kneading / crushing / classification process)
The following components are premixed for 5 minutes using a Henschel mixer, and then melt-kneaded using a twin-screw extruder at a cylinder set temperature of 110 ° C., a barrel rotation speed of 300 rpm, and a raw material supply speed of 20 kg / hour. Got
Bundling resin (acrystalline polyester resin (aromatic alcohol component: PO-BPA (propoxydated bisphenol A) and EO-BPA (ethoxylated bisphenol A), acid component: fumaric acid and anhydrous merit acid))
Resin A 42% by mass
Resin B 42% by mass
-Coloring agent: Carbon black (manufactured by Cabot Corporation, product name: Regal330) 6% by mass
-Release agent: Wax (1) (ester type, Tm: 76 ° C) 3% by mass
-Release release agent Dispersant: Styrene acrylic copolymer resin (manufactured by Mitsui Chemicals, Inc., trade name: SA800) 5% by mass
-Charge control agent: salicylic acid compound (Orient Chemical Industry Co., Ltd., trade name: Bontro E84) 2% by mass

The obtained molten kneaded product is cooled with a cooling belt, coarsely pulverized using a cutting mill, then finely pulverized using a jet crusher, and further classified using a wind classifier to obtain average particles. Toner particles (toner matrix particles) having a diameter of 6.5 μm were obtained.

(External process)
To 100 parts by mass of the toner particles (toner matrix particles) obtained in the above step, 0.5 parts by mass of the silica fine particles (A-1) and 0.45 parts by mass of the silica fine particles (B-1) are added to the stirring blade. The external toner was obtained by stirring for 2 minutes with an air flow mixer (manufactured by Mitsui Mining Co., Ltd., Henchel Mixer) in which the tip speed of the particles was set to 40 m / sec.

(Manufacturing process of two-component developer)
The obtained external toner and the carrier (1) are adjusted and mixed so that the concentration of the external toner is 7% by mass with respect to the total amount of the two-component developer, and the two components have a toner concentration of 7% by mass. A developer was obtained.

[Examples 2 to 22, Comparative Examples 1 to 8]
Table 2 below shows a list of the binder resins used in Examples and the like, and Table 3 shows a list of waxes used in Examples and the like. The list of external additives used in Examples and the like is as shown in Table 1 above. An external toner and a two-component developer were obtained in the same manner as in Example 1 except that these materials were combined as shown in Table 4 below. In Comparative Example 8, the titanium oxide used as the external additive is trade name T805 (average particle size: 21 nm) manufactured by Evonik Industries.

A list of evaluation results for the external toner and the two-component developer obtained in these examples and the like is shown in Table 5 below.

As is clear from Table 5, the content of the THF insoluble matter in the toner particles is 10% by mass or more and 30% by mass or less, the external additive contains the first external additive and the second external additive, and the first. The external additive is silica fine particles having a volume average particle diameter of 20 nm or more and 50 nm or less, in which silica derived from the sol-gel method is hydrophobicized by a hydrophobic treatment agent, and the second external additive is silica derived from the vapor phase method. Is a silica fine particle having a volume average particle diameter of 5 nm or more and 15 nm or less, which is hydrophobicized by a hydrophobic treatment agent, and has an A / B of more than 0.3 and less than 1.5. And the two-component developer was excellent in the evaluation of the environmental charge stability and the charge stability throughout the life.

On the other hand, the toners and the two-component developer of Comparative Examples 1 to 8 which do not satisfy these requirements were inferior to the Examples in the evaluation of at least one of the environmental charge stability and the charge stability throughout the life. ..

In Comparative Example 1 in which the content of the THF insoluble matter in the toner particles is less than 10% by mass, the evaluation of the environmental charge stability after the continuous print test and the evaluation of the charge stability throughout the life are inferior to those of the examples. Was there. Further, in Comparative Example 2 in which the content of the THF insoluble matter in the toner particles exceeded 30% by mass, the evaluation of the environmental charge stability was inferior to that of the Example.

In Comparative Example 3 in which A / B (content of the first external additive / content of the second external additive) was 0.3 or less, the evaluation of the environmental charge stability was inferior to that of the example. Further, in Comparative Example 4 having an A / B of 1.5 or more, the evaluation of charge stability throughout life was inferior to that of the Example.

In Comparative Example 5, the first external additive is not the silica derived from the sol-gel method hydrophobized by the hydrophobizing agent, but the silica derived from the gas phase method hydrophobized by the hydrophobizing agent. The evaluation of charge stability was inferior to that of the examples. Further, in Comparative Example 6 in which the volume average particle size of the first external additive exceeds 50 nm, the evaluation of the environmental charge stability after the continuous print test was inferior to that of the Example.

In Comparative Example 7 in which the volume average particle size of the second external additive exceeds 15 nm, the evaluation of the environmental charge stability after the continuous print test and the evaluation of the charge stability throughout the life were inferior to those of the Examples.

In Comparative Example 8 in which titanium oxide particles were added as an external additive without adding the first external additive, the evaluation of charge stability throughout life was inferior to that of the examples.

Further, Example 1 in which the content of the THF insoluble matter in the toner particles is 15% by mass or more and 20% by mass or less includes Example 2 in which the content of the THF insoluble matter is less than 15% by mass, and the THF insoluble content. It can be seen that the evaluation of the environmental charge stability and the charge stability throughout the life is more excellent than that of Example 3 in which the content exceeds 20% by mass.

Examples 1, 6 and 7 having an A / B of more than 0.7 and less than 1.3 are Examples 4 and 5 having an A / B of 0.7 or less and A / B of 1.3 or more. It can be seen that the evaluation of the environmental charge stability and the charge stability throughout the life is superior as compared with Examples 8 and 9.

Example 1 in which the volume average particle size of the first external additive is 25 nm or more and 35 nm or less has continuous environmental charge stability as compared with Example 10 in which the volume average particle size of the first external agent exceeds 35 nm. It can be seen that the evaluation after the print test and the evaluation of the charge stability throughout the life are more excellent.

Example 1 in which the volume average particle diameter of the second external additive is 5 nm or more and 9 nm or less has continuous environmental charge stability as compared with Example 11 in which the volume average particle diameter of the second external additive exceeds 9 nm. It can be seen that the evaluation after the print test and the evaluation of the charge stability throughout the life are more excellent.

In Example 1 in which the first external additive is silica fine particles hydrophobized by HMDS and the second external additive is silica fine particles hydrophobicized by DDS, the first external additive is hydrophobized by oil. It can be seen that the evaluation of the environmental charge stability after the continuous print test and the evaluation of the charge stability throughout the life are more excellent than those of Example 12 which is the silica fine particles. Further, it can be seen that the evaluation of the charge stability throughout the life is more excellent than in Example 13 in which the second external additive is silica fine particles hydrophobized by HMDS.

It can be seen that the toners and the two-component developer of Examples 1 to 22 having T1-T2 of 15 ° C. or higher and 30 ° C. or lower are excellent in evaluation of environmental charge stability and charge stability throughout life. Further, Example 1 in which T1-T2 is 17 ° C. or higher and 23 ° C. or lower is environmentally charged as compared with Example 14 in which T1-T2 exceeds 23 ° C. and Example 15 in which T1-T2 is lower than 17 ° C. It can be seen that the evaluation of the stability after the continuous print test and the evaluation of the charge stability throughout the life are more excellent.

The toners and the two-component developer of Examples 1 to 22 in which the content of the styrene acrylic resin in the toner particles is 1% by mass or more and 10% by mass or less are excellent in the evaluation of the environmental charge stability and the charge stability throughout the life. You can see that. Further, Example 1 in which the content of the styrene acrylic resin is 3% by mass or more and 8% by mass or less has environmental charge stability as compared with Example 16 in which the content of the styrene acrylic resin is less than 3% by mass. It can be seen that the evaluation after the continuous print test and the evaluation of the charge stability throughout the life are more excellent (in particular, the evaluation of the charge stability through the life is more excellent). Further, it can be seen that the evaluation of the environmental charge stability is more excellent than that of Example 17 in which the content of the styrene acrylic resin exceeds 8% by mass.

Examples 1, 19 and 20 having a peak top molecular weight of 4000 or more and 6500 or less of the tetrahydrofuran-soluble component in the toner particles have a charge stability throughout life as compared with Example 18 having a peak top molecular weight of less than 4000. It turns out that the evaluation of is better. Further, it can be seen that the evaluation of the environmental charge stability is more excellent than that of Example 21 in which the peak top molecular weight exceeds 8000.

It can be seen that Example 1 in which the carrier is an iron powder carrier is more excellent in the evaluation of environmental charge stability as compared with Example 22 in which the carrier is a ferrite carrier.

<Other embodiments>
It should be noted that the embodiments disclosed this time are examples in all respects and do not serve as a basis for a limited interpretation. Therefore, the technical scope of the present invention is not construed solely by the embodiments described above, but is defined based on the description of the scope of claims. In addition, the technical scope of the present invention includes all modifications within the meaning and scope equivalent to the scope of claims.

Claims (7)

A toner in which an external additive is attached to the surface of toner particles containing an amorphous polyester resin and wax.
The content of the tetrahydrofuran insoluble matter in the toner particles is 10% by mass or more and 30% by mass or less.
The external preparation includes a first external addition agent and a second external preparation agent.
The first external additive is silica fine particles having a volume average particle diameter of 20 nm or more and 50 nm or less, in which silica derived from the sol-gel method is hydrophobized by a hydrophobizing treatment agent.
The second external additive is silica fine particles having a volume average particle diameter of 5 nm or more and 15 nm or less, in which silica derived from the vapor phase method is hydrophobicized by a hydrophobic treatment agent.
Assuming that the content of the first external additive in the toner is A and the content of the second external additive is B, the toner is characterized in that A / B is more than 0.3 and less than 1.5. The toner according to claim 1.
The wax is an ester wax,
Assuming that the endothermic peak temperature at the time of temperature rise derived from the wax is T1 and the heat generation peak temperature at the time of cooling derived from the wax is T2 measured by using a differential scanning calorimeter, T1-T2 is 15 ° C. or higher and 30 ° C. or lower. Toner characterized by being. The toner according to claim 1 or 2.
The toner particles contain a styrene acrylic resin and contain.
The toner is characterized in that the content of the styrene acrylic resin in the toner particles is 1% by mass or more and 10% by mass or less. The toner according to any one of claims 1 to 3.
The first external additive is silica fine particles hydrophobized with hexamethyldisilazane.
The second external additive is a toner characterized by being silica fine particles hydrophobicized with dimethyldichlorosilane. The toner according to claim 4.
Assuming that the content of the first external additive in the toner is A and the content of the second external additive is B, the toner is characterized in that A / B is more than 0.7 and less than 1.3. The toner according to any one of claims 1 to 5.
A toner characterized in that the peak top molecular weight of the tetrahydrofuran-soluble component in the toner particles measured by gel permeation chromatography is 4000 or more and 6500 or less. A two-component developer comprising the toner according to any one of claims 1 to 6 and a carrier.
The carrier is a two-component developer characterized by being an iron powder carrier.