JP6560542B2 - Toner and two-component developer - Google Patents

Description

  The present invention relates to a toner and a two-component developer containing the toner, and more particularly to a toner used in an electrophotographic image forming apparatus.

  In order to improve the low-temperature fixability of the toner, it is known to use a binder resin in which a crystalline polyester resin is dispersed in an amorphous polyester resin. And the technique which solves the subject which arises by using such a binder resin is also reported. For example, in Japanese Patent No. 4,603,837 (Patent Document 1), in a toner containing a crystalline polyester resin and an amorphous polyester resin as a binder resin, a charge control agent, and a release agent, iron of salicylic acid is used as the charge control agent. Alternatively, there is a description of improving the chargeability by using a zirconium complex.

  Japanese Patent Application Laid-Open No. 2014-26075 (Patent Document 2) discloses that a toner containing a crystalline resin such as a crystalline polyester resin, a colorant, and a charge control agent includes phenols and aldehydes as charge control agents. There is a description that by containing a polycondensate obtained by the polycondensation reaction, image density unevenness due to a decrease in transferability due to environmental changes is solved.

  Japanese Patent Laid-Open No. 2014-178547 (Patent Document 3) discloses a specific charge control agent containing a specific layered inorganic mineral in a toner containing a binder resin, a colorant, a release agent, and a charge control agent. By using an external additive containing insulating inorganic particles, the layered inorganic mineral and insulating inorganic particles satisfy the specified ratios, thereby suppressing deterioration of transferability, filming resistance, and toner fluidity, and charging stability. There is a description of making it.

Japanese Patent No. 4603737 JP 2014-26075 A JP 2014-178547 A

  However, when a toner containing a binder resin in which a crystalline polyester resin is dispersed in an amorphous polyester resin is used, image defects such as fogging and rustling may occur when a high voltage AC superimposed bias is applied during development. Is likely to occur. Further, the charge holding ability of the toner is lowered, and the developability is deteriorated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a toner that solves the above-described problems of the prior art, has excellent low-temperature fixability, and can suppress image defects such as fogging and blurring, and deterioration of developability. Another object of the present invention is to provide a two-component developer containing such toner.

  The present inventor has found that when a toner containing a binder resin in which a crystalline polyester resin is dispersed in an amorphous polyester resin is used, image defects such as fogging and blurring, deterioration of developability, and toner The cause of the decrease in charge retention ability was investigated.

  Crystalline polyester resin has a relatively low dielectric constant compared to amorphous polyester. Therefore, when a high voltage AC superimposed bias is applied during development, electric force lines concentrate on the amorphous polyester resin region, and charge injection (or charge release from the photoconductor) easily occurs. It is considered that image defects such as fogging and roughness are likely to occur. In addition, it is considered that by introducing a crystalline polyester resin, the toner aromatic ring concentration is lowered, the charge holding ability of the toner is lowered, and the developability is deteriorated.

Under such circumstances, the present inventor has made extensive studies to achieve the above object, and as a result, the toner containing the binder resin in which the crystalline polyester resin is dispersed in the amorphous polyester resin is subjected to a hydrophobic treatment. By adding titanium oxide fine particles having a primary particle diameter of 20 nm to 100 nm and burying the titanium oxide fine particles in the toner particles, the surface presence ratio of the titanium oxide fine particles to the toner particle surface is set to 2 to 20%. The present invention has been completed.
By allowing fine particles of titanium oxide having a specific range of high dielectric constant to be present on the surface of the toner particles, the dielectric constant of the toner is increased, and when a high voltage AC superimposed bias is applied during development, It is estimated that charge injection (or charge release from the photoreceptor) is suppressed. Further, it is presumed that the charge holding ability of the toner is enhanced by increasing the dielectric constant.

That is, the toner of the present invention is a toner containing a binder resin containing an amorphous polyester resin and a crystalline polyester resin, and an external additive.
The amorphous polyester resin has an SP value of 10.5 to 12.5 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 . An amorphous polyester resin,
The crystalline polyester resin is obtained by polycondensing a dicarboxylic acid monomer mainly containing an aliphatic dicarboxylic acid having 9 to 22 carbon atoms and a diol monomer mainly containing an aliphatic diol having 2 to 10 carbon atoms. A crystalline polyester resin having an SP value of 9.3 to 10.0 ,
The external additive includes hydrophobized titanium oxide fine particles having a primary particle diameter of 20 nm to 100 nm, and the titanium oxide fine particles are embedded in toner particles containing the binder resin, and The surface presence rate of titanium oxide fine particles is 2 to 20%.

  In a preferred example of the toner of the present invention, the hydrophobic treatment is performed with hexamethyldisilazane, and the hydrophobicity of the hydrophobized titanium oxide fine particles is 95% or more and 100% or less.

  A two-component developer according to the present invention includes the toner and a carrier described above.

  According to the toner of the present invention, it is possible to provide a toner that is excellent in low-temperature fixability and that can suppress image defects such as fogging and roughness and deterioration of developability.

  Further, according to the two-component developer of the present invention, by using such a toner, a two-component developer that has excellent low-temperature fixability and can suppress image defects such as fogging and blurring and deterioration of developability. Can be provided.

[toner]
Hereinafter, the toner of the present invention will be described in detail. The toner of the present invention is a toner containing a binder resin containing an amorphous polyester resin and a crystalline polyester resin, and an external additive, wherein the amorphous polyester resin contains terephthalic acid or isophthalic acid as a main component. A non-crystalline polyester resin obtained by polycondensation of a dicarboxylic acid monomer and a diol monomer containing ethylene glycol as a main component, wherein the crystalline polyester resin is mainly composed of an aliphatic dicarboxylic acid having 9 to 22 carbon atoms. A crystalline polyester resin obtained by polycondensation of a dicarboxylic acid monomer contained as a main component and a diol monomer containing a C 2-10 aliphatic diol as a main component, wherein the external additive is a hydrophobized primary Titanium oxide fine particles having a particle diameter of 20 nm to 100 nm are contained in the toner particles containing a binder resin. Tan fine particles are buried, the surface abundance of titanium oxide fine particles to the surfaces of the toner particles, characterized in that 2 to 20%.

  The toner of the present invention includes toner mother particles (toner particles) containing a binder resin and titanium oxide fine particles having a primary particle diameter of 20 nm to 100 nm that are embedded in the surface of the toner mother particles and subjected to a hydrophobic treatment. The toner base particles generally further contain an internal additive such as a release agent, a colorant, and a charge control agent. The toner of the present invention preferably has a volume average particle diameter of 5 μm to 10 μm.

[Binder resin]
The binder resin used in the toner of the present invention includes at least the amorphous polyester resin and the crystalline polyester resin. The crystalline polyester resin and internal additives such as a release agent, a colorant, and a charge control agent are dispersed in the amorphous polyester resin.

  In general, a crystalline polyester resin can reduce the softening temperature and melt viscosity of the toner without lowering the mechanical strength of the toner as compared to the amorphous polyester resin. It is known that the low-temperature fixability of toner can be improved when used in combination with a conductive polyester resin. Further, in the binder resin used in the toner of the present invention, the amorphous polyester resin and the crystalline polyester resin are different in the main component of the dicarboxylic acid monomer and in some cases even the main component of the diol monomer. Can be more reliably suppressed, and the effect of improving the low-temperature fixability is great.

  In the present invention, the main component of the dicarboxylic acid monomer and the main component of the diol monomer refer to a monomer having the maximum molar content among the monomers constituting each, but in the case of a single monomer (that is, , Terephthalic acid, isophthalic acid, ethylene glycol, aliphatic dicarboxylic acid having 9 to 22 carbon atoms, or aliphatic diol having 2 to 10 carbon atoms is 100%).

  In the toner of the present invention, the mass ratio (A / B) of the crystalline polyester resin (A) and the amorphous polyester resin (B) in the binder resin is not particularly limited, and is appropriately determined as necessary. Although it can be adjusted, 3/97 to 20/80 is preferable from the viewpoint of achieving both low-temperature fixability and hot offset resistance.

In the present invention, the amorphous resin and the crystalline resin are distinguished by the crystallinity index. A resin having a crystallinity index in the range of 0.6 to 1.5 is defined as a crystalline resin, and the crystallinity index is 0.6. A resin that is less than or exceeds 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 serves as an index of the degree of crystallization of the resin, and is defined by the ratio between the softening temperature and the maximum endothermic peak temperature (softening temperature / maximum endothermic peak temperature). Here, the highest endothermic peak temperature refers to the temperature of the peak on the highest temperature side among the observed endothermic peaks. In the crystalline polyester resin, the highest peak temperature is the melting point, and in the amorphous polyester resin, the peak on the highest temperature side is the glass transition point.
The degree of crystallization can be controlled by adjusting the type and ratio of raw material monomers, production conditions (for example, reaction temperature, reaction time, cooling rate) and the like.

[Amorphous polyester resin]
The amorphous polyester resin used in the toner of the present invention is an amorphous polyester resin obtained by polycondensation of 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. It is.

  The dicarboxylic acid monomer used for 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.

  The dicarboxylic acid monomer may contain an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid other than terephthalic acid and isophthalic acid. Examples of the aromatic dicarboxylic acid other than terephthalic acid and isophthalic acid include fumaric acid, and examples of the aliphatic dicarboxylic acid include adipic acid, sebacic acid, and succinic acid. The dicarboxylic acid monomer may also include ester-forming derivatives of terephthalic acid or isophthalic acid, ester-forming derivatives of aromatic dicarboxylic acids other than terephthalic acid and isophthalic acid, and ester-forming derivatives of aliphatic dicarboxylic acids. In the present invention, ester-forming derivatives include carboxylic acid anhydrides and alkyl esters. In addition, when using dicarboxylic acid monomers other than terephthalic acid and isophthalic acid, this dicarboxylic acid monomer may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the synthesis of the amorphous polyester resin, a tricarboxylic or higher polycarboxylic acid monomer may be used together with the dicarboxylic acid monomer. As the trivalent or higher polycarboxylic acid monomer, trivalent or higher polycarboxylic acid such as trimellitic acid or pyromellitic acid or an ester-forming derivative thereof can be used. When using trivalent or higher polycarboxylic acid monomers, these polycarboxylic acid monomers may be used singly or in combination of two or more.

  The diol monomer used for 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.

  The diol monomer can include 1,3-propylene glycol, 1,4-butanediol, and the like. When using diol monomers other than ethylene glycol, these diol monomers may be used alone or in combination of two or more.

  The amorphous polyester resin used in the toner of the present invention can be produced in the same manner as in a normal polyester production method. For example, by performing a polycondensation reaction in a nitrogen gas atmosphere at a temperature of 190 to 240 ° C. using a dicarboxylic acid monomer, a diol monomer, and optionally a polycarboxylic acid monomer having a valence of 3 or more, an amorphous property A polyester resin can be synthesized.

  In the above polycondensation reaction, the reaction ratio between the diol monomer and the carboxylic acid monomer (including a dicarboxylic acid monomer and, optionally, a tricarboxylic or higher polycarboxylic acid monomer) is an equivalent ratio [OH] / hydroxyl group to carboxyl group. [COOH] is preferably 1.3 / 1 to 1 / 1.2. In the polycondensation reaction, the molar content of the dicarboxylic acid monomer in the carboxylic acid monomer is preferably 80 to 100%. Furthermore, in the polycondensation reaction, an esterification catalyst such as dibutyltin oxide or titanium alkoxide (for example, tetrabutoxy titanate) can be used as necessary.

  The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50 to 70 ° C. from the viewpoints of fixability, storage stability and durability.

  The softening point (Tm) of the amorphous polyester resin is preferably 100 to 150 ° C. from the viewpoint of achieving both low-temperature fixability and hot offset resistance.

  The molecular weight of the amorphous polyester resin is determined by gel peak permeation chromatography (GPC), the peak top molecular weight (Mp) of tetrahydrofuran (THF) soluble matter, and the heat resistance, heat storage property and low temperature of the toner. From the viewpoint of coexistence of fixability, 3000 to 10500 is preferable. In GPC, tetrahydrofuran (THF) is used as a mobile phase, and polystyrene is used as a standard substance. The peak top molecular weight refers to a molecular weight showing the maximum peak height in a chromatogram obtained by GPC measurement.

  The acid value of the amorphous polyester resin is preferably 0 to 60 mgKOH / g from the viewpoint of charging characteristics, and the hydroxyl value of the amorphous polyester resin is preferably 0 to 50 mgKOH / g from the viewpoint of hot offset resistance. preferable.

  The SP value (solubility parameter) of the amorphous polyester resin is preferably 10.5 to 12.5.

  In the toner of the present invention, the content of the amorphous polyester resin is not particularly limited, but is preferably 60 to 80% by mass in the toner base particles.

[Crystalline polyester resin]
The crystalline polyester resin used in the toner of the present invention comprises a dicarboxylic acid monomer containing an aliphatic dicarboxylic acid having 9 to 22 carbon atoms as a main component and a diol monomer containing an aliphatic diol having 2 to 10 carbon atoms as a main component. It is a crystalline polyester resin obtained by polycondensation.

  The dicarboxylic acid monomer used for the synthesis of the crystalline polyester resin contains an aliphatic dicarboxylic acid having 9 to 22 carbon atoms as a main component. Here, the molar content of the aliphatic dicarboxylic acid having 9 to 22 carbon atoms in the dicarboxylic acid monomer is preferably 80% or more and 100% or less.

  Examples of the aliphatic dicarboxylic acid having 9 to 22 carbon atoms include azelaic acid, zebacic acid, 1,10-decanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, and the like. The dicarboxylic acid monomer can also contain ester-forming derivatives of these aliphatic dicarboxylic acids. In addition, these dicarboxylic acid monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the synthesis of the crystalline polyester resin, a tricarboxylic or higher polycarboxylic acid monomer may be used together with the dicarboxylic acid monomer. As the trivalent or higher polycarboxylic acid monomer, trivalent or higher polycarboxylic acid such as trimellitic acid or pyromellitic acid or an ester-forming derivative thereof can be used. When using trivalent or higher polycarboxylic acid monomers, these polycarboxylic acid monomers may be used singly or in combination of two or more.

  The diol monomer used for the synthesis of the crystalline polyester resin contains an aliphatic diol having 2 to 10 carbon atoms as a main component. Here, the molar content of the aliphatic diol having 2 to 10 carbon atoms in the diol monomer is preferably 80% or more and 100% or less.

  Examples of the aliphatic diol having 2 to 10 carbon atoms include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and the like. In addition, these diol monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the synthesis of the crystalline polyester resin, a trivalent or higher valent polyol monomer may be used together with the diol monomer. As the trivalent or higher polyol monomer, glycerin, trimethylolpropane or the like can be used. When using a trivalent or higher polyol monomer, the polyol monomer may be used alone or in combination of two or more.

  The crystalline polyester resin used in 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 performed at a temperature of 190 to 240 ° C. in a nitrogen gas atmosphere using a dicarboxylic acid monomer, a diol monomer, and optionally a tricarboxylic or higher polycarboxylic acid monomer or a trivalent or higher polyol monomer. By doing so, a crystalline polyester resin can be synthesized.

  In the polycondensation reaction, a hydroxyl group of a polyol monomer (including a diol monomer and optionally a trivalent or higher polyol monomer), a carboxylic acid monomer (a dicarboxylic acid monomer, and optionally a trivalent or higher polycarboxylic acid monomer) The equivalent ratio (including OH) to the carboxyl group (OH group / COOH group) is preferably 1.01 to 1.14 from the viewpoint of storage stability. In the polycondensation reaction, the molar content of the dicarboxylic acid monomer in the carboxylic acid monomer is preferably 90 to 100%. The smaller the molar content of the dicarboxylic acid monomer, the lower the rate and speed of crystallization and the insufficient toner aggregation resistance. Furthermore, in the polycondensation reaction, the molar content of the diol monomer in the polyol monomer is preferably 80 to 100%. In the polycondensation reaction, an esterification catalyst such as dibutyltin oxide or titanium alkoxide (for example, tetrabutoxy titanate) can be used as necessary.

  The crystalline polyester resin has a melting point (Tmp) of preferably 40 ° C. or higher, and more preferably 60 to 90 ° C. from the viewpoint of fixability, storage stability, durability, and the like.

  The softening point (Tm) of the crystalline polyester resin is preferably 65 to 110 ° C. from the viewpoints of low temperature fixability and blocking resistance.

  The crystalline polyester resin preferably has a softening point (Tm) to melting point (Tmp) ratio (Tm / Tmp) of 1.0 to 1.4 from the viewpoint of crystallization speed and blocking resistance.

  The molecular weight of the crystalline polyester resin is such that the peak top molecular weight (Mp) of the tetrahydrofuran (THF) soluble component measured using gel permeation chromatography (GPC) is from the viewpoint of storage stability and low temperature fixability, etc. 10,000 to 90,000 are preferable. In GPC, tetrahydrofuran (THF) is used as a mobile phase, and polystyrene is used as a standard substance. The peak top molecular weight refers to a molecular weight showing the maximum peak height in a chromatogram obtained by GPC measurement.

  The acid value of the crystalline polyester resin is preferably 0 to 60 mgKOH / g from the viewpoint of charging characteristics, and the hydroxyl value of the crystalline polyester resin is preferably 0 to 40 mgKOH / g from the viewpoint of hot offset resistance.

  The SP value (solubility parameter) of the crystalline polyester resin is preferably 9.3 to 10.0. When the SP value is less than 9.3, the compatibility with the amorphous polyester resin becomes too low, and the durability may be insufficient. On the other hand, if the SP value exceeds 10.0, the Tg of the binder resin may decrease, and the blocking resistance may decrease.

  In the toner of the present invention, the content of the crystalline polyester resin is not particularly limited, but is preferably 3 to 20% by mass in the toner base particles.

[Release agent]
The release agent is added to impart releasability to the toner when the toner is fixed on the recording medium. In the toner of the present invention, the release agent is dispersed in the amorphous polyester resin. The release agent used in the toner of the present invention is not particularly limited, but polypropylene wax, polyethylene wax and derivatives thereof, microcrystalline wax, carnauba wax, rice wax, candelilla wax, synthetic ester wax and the like. Can be used. As synthetic ester wax, Nissan Electol wax (manufactured by NOF Corporation; WEP-2, WEP-3, WEP-4, WEP-5, WEP-6, WEP-7, WEP-8, WEP-9, WEP) -10). In the toner of the present invention, the content of the release agent is not particularly limited, but is preferably 1 to 5% by mass in the toner base particles.

[Colorant]
As the colorant, known pigments and dyes generally used for toners can be used. Specifically, the following colorants can be used.

  As a black toner colorant, carbon black, magnetite, or the like can be used.

  Examples of the colorant for yellow toner include C.I. I. Pigment Yellow 1, 3, 74, 97, 98, etc. acetoacetic acid arylamide monoazo yellow pigments, C.I. I. Pigment Yellow 12, 13, 13, 14, etc., acetoacetic acid arylamide disazo yellow pigments, C.I. I. Condensed monoazo yellow pigments such as CI Pigment Yellow 93 and 155; I. Other yellow pigments such as C.I. Pigment Yellow 180, 150 and 185, C.I. I. Solvent Yellow 19, 77, 79, C.I. I. A yellow dye such as Disperse Yellow 164 can be used.

  Examples of the colorant for magenta toner include C.I. I. Pigment Red 48, 49: 1, 53: 1, 57, 57: 1, 81, 122, 5, 146, 184, 238, C.I. I. Red or red pigments such as CI Pigment Violet 19; I. Red dyes such as Solvent Red 49, 52, 58 and 8 can be used.

  Examples of the colorant for cyan toner include C.I. I. Pigment Blue 15: 3, 15: 4, and the like, and blue dyes and pigments of copper phthalocyanine and derivatives thereof; C.I. I. Green pigments such as CI Pigment Green 7 and 36 (phthalocyanine green) can be used.

  In the toner of the present invention, the content of the colorant is not particularly limited, but is preferably 2 to 10% by mass in the toner base particles.

[Charge control agent]
The charge control agent is added in order to impart preferable chargeability to the toner. As the charge control agent that can be used in the toner of the present invention, a charge control agent for positive charge control or negative charge control can be used. Examples of the charge control agent for controlling positive charge include nigrosine dyes and derivatives thereof, triphenylmethane derivatives, quaternary ammonium salts, quaternary phosphonium salts, quaternary pyridinium salts, guanidine salts and amidine salts. As the charge control agent for controlling negative charge, chromium azo complex dye, iron azo complex dye, cobalt azo complex dye, salicylic acid or its derivative chromium / zinc / aluminum / boron complex or salt compound, naphtholic acid or its derivative chromium / zinc -Aluminum-boron complex or salt compound, chromium-zinc-aluminum-boron complex or salt compound of benzylic acid or its derivative, long chain alkyl carboxylate, long chain alkyl sulfonate, etc. In the toner of the present invention, the content of the charge control agent is not particularly limited, but is preferably 0.5 to 5% by mass in the toner base particles.

[External additive]
The external additive used in the toner of the present invention includes titanium oxide fine particles having a primary particle diameter of 20 nm to 100 nm that have been subjected to a hydrophobic treatment, and the titanium oxide fine particles are embedded in the toner particle surfaces. The surface presence rate of the titanium oxide fine particles with respect to the toner surface is 2 to 20%. Titanium oxide has a high dielectric constant and can sharpen the charge distribution. By hydrophobizing the surface of titanium oxide, dispersibility can be improved and aggregation can be suppressed. By setting the primary particle diameter of the titanium oxide fine particles to 20 nm to 100 nm, it is possible to prevent detachment of titanium oxide from the toner surface and to suppress image defects due to the release of titanium oxide. By setting the surface presence ratio of titanium oxide fine particles to the toner surface to 2 to 20%, since titanium oxide has a high dielectric constant, even if the crystalline polyester resin has a lower dielectric constant than the amorphous polyester, development is possible. Concentration of electric lines of force in the amorphous polyester resin region when a high voltage AC superimposed bias is sometimes applied can be suppressed. As a result, image defects such as fogging and blurring due to charge injection (or charge release from the photoreceptor) to the photoreceptor can be suppressed.

  The relative dielectric constant (ratio of the dielectric constant of the substance to the vacuum dielectric constant) of the titanium oxide fine particles used in the toner of the present invention is desirably 10 to 200. As the titanium oxide fine particles, rutile type and anatase type titanium oxide fine particles can be used, but rutile type titanium oxide has a higher dielectric constant than anatase type titanium oxide and is more preferable. For example, the relative dielectric constant of titanium oxide is 114 for the rutile type and 48 for the anatase type (“Safety of Titanium Oxide (Including Nano Titanium Oxide)”), Japan Titanium Oxide Industry Association, http: / /www.sankatitan.org/sankatitan/2014.6ansen.pdf).

  The primary particle size of the titanium oxide fine particles refers to the average primary particle size of the titanium oxide fine particles after the hydrophobization treatment.

(Method for producing titanium oxide fine particles)
In the toner of the present invention, the titanium oxide fine particles have a primary particle size of 20 nm to 100 nm, and rutile or anatase type titanium oxide fine particles can be used. As a method for producing rutile-type titanium oxide fine particles, for example, a method described in Japanese Patent Application Laid-Open No. 2001-26423, that is, a titania sol having a rutile nucleus is prepared by hydrolyzing an aqueous titanium tetrachloride solution. There is a method in which titanium oxide fine particles are obtained by heat treatment after fractionation. As a method for producing anatase type titanium oxide fine particles, for example, a method described in JP 2000-10335 A, that is, a solution in which a raw material such as ilmenite ore is dissolved in sulfuric acid is hydrolyzed and granulated. There is a method of obtaining titanium oxide fine particles by drying at a high temperature after drying.

(Hydrophobic treatment)
As a hydrophobizing treatment method, a method of reacting a hydrophobizing agent on the surface of titanium oxide fine particles can be used. Specifically, titanium oxide fine particles are placed in a four-necked flask equipped with a stirring member and a thermometer and through which an introduction tube for introducing an inert gas such as a hydrophobizing agent and nitrogen gas is inserted. While maintaining stirring, a hydrophobizing agent and an inert gas are introduced, and the titanium oxide fine particles can be hydrophobized by reacting for a predetermined time (for example, 2 to 8 hours). As the hydrophobizing agent, for example, silane coupling agents such as hexamethyldisilazane, methyltrimethoxysilane, dimethyldimethoxysilane, and trimethylchlorosilane, silicone oil, silicone varnish, and the like can be used, and hexamethyldisilazane is preferable. In addition, the hydrophobized titanium oxide fine particles (hereinafter also referred to as hydrophobic titanium oxide fine particles) preferably have a hydrophobicity of 95% or more and 100% or less. Titanium oxide fine particles having a hydrophobicity of 95% or more and 100% or less that have been hydrophobized with hexamethyldisilazane are less likely to be caught by the crystalline polyester resin even if the crystalline polyester resin is attached to the developing roller. It becomes difficult to be fixed to the surface of the developing roller. Further, the hydrophobized titanium oxide fine particles preferably have a loss on drying of 0.8% by mass or less.

  In the toner of the present invention, the addition amount of the titanium oxide fine particles having a hydrophobized primary particle diameter of 20 nm to 100 nm is not particularly limited, but is 0.1 to 1 part by mass with respect to 100 parts by mass of the toner base particles. Is preferred.

(External additives other than titanium oxide fine particles)
As the external additive used in the toner of the present invention, for example, inorganic fine particles having an average particle size of 7 nm to 50 nm other than titanium oxide fine particles can be used for the purpose of imparting fluidity to the toner. Examples of the inorganic fine particles include inorganic fine particles such as silica and alumina, and those obtained by subjecting the inorganic fine particles to a surface treatment (hydrophobization treatment) with a silane coupling agent, a titanium coupling agent, or silicone oil. In the toner of the present invention, the amount of the external additive other than the titanium oxide fine particles is not particularly limited, but is preferably 0.8 to 2 parts by mass with respect to 100 parts by mass of the toner base particles.

  The toner of the present invention can be used as a one-component developer, but as will be described later, the toner and carrier mixture of the present invention can also be used as a two-component developer.

[Toner production method]
Next, a method for producing the toner of the present invention will be described. The toner of the present invention can be produced by a known method such as a kneading and pulverizing method or an aggregating method. For example, when the toner of the present invention is produced by a kneading and pulverizing method, first, a binder resin containing an amorphous polyester resin and a crystalline polyester resin, and a release agent, a colorant, a charging agent, which are appropriately selected as necessary. Internal additives such as control agents are mixed with an air flow mixer such as a Henschel mixer, and the resulting raw material mixture is kneaded at a temperature of about 100 to 180 ° C. with a melt kneader such as a biaxial kneader or an open roll kneader. . Then, the obtained melt-kneaded product is cooled and solidified, the solidified product is pulverized by an air pulverizer such as a jet mill, and the toner base particles are produced by adjusting the particle size such as classification as required. As a method for adding the external additive, a method in which the toner base particles and the external additive are mixed with an air flow mixer such as a Henschel mixer is generally used.

[Two-component developer]
The case where the toner of the present invention is used as a two-component developer will be described below. The two-component developer includes the toner of the present invention described above and a carrier. For example, the toner can be obtained using a mixer such as a Nauta mixer (trade name: VL-0, manufactured by Hosokawa Micron Corporation). And a carrier. Further, the mixing ratio of the toner and the carrier is preferably a mass ratio of 10:90 to 5:95, for example.

[Career]
As the carrier, magnetic particles having a volume average particle diameter of 20 to 45 μm can be used. If the volume average particle diameter of the carrier is less than 20 μm, white spots may occur in the resulting image due to the carrier moving from the developing roller to the photoreceptor during development. On the other hand, if it exceeds 45 μm, the dot reproducibility deteriorates and the image becomes rough. In the present invention, the volume average particle diameter of the carrier is determined by using a dry dispersion apparatus RODOS (manufactured by SYMPATEC) and a dispersion pressure of 3.0 bar using a laser diffraction particle size distribution measuring apparatus HELOS (manufactured by SYMPATEC). This is the value when measured.

  Regarding the saturation magnetization of the carrier, the lower the saturation magnetization, the softer the magnetic brush (formed on the surface of the developing roller) in contact with the photoconductor, so that an image faithful to the electrostatic latent image can be obtained, but the saturation magnetization is too low. As a result, carriers adhere to the surface of the photoreceptor, and white spots are likely to occur. On the other hand, if the saturation magnetization is too high, it becomes difficult to obtain an image faithful to the electrostatic latent image due to the stiffening of the magnetic brush. For this reason, it is preferable that the saturation magnetization of a carrier exists in the range of 30-100 emu / g.

  As such a carrier, a coated carrier in which a coating layer is provided on the surface of magnetic core particles is generally used. Known magnetic particles can be used as the core particles, but ferrite particles are preferred. When ferrite particles are used, carriers with high saturation magnetization can be obtained, and the amount of carriers attached to the photoreceptor can be reduced. Known ferrite particles can be used, such as zinc ferrite, nickel ferrite, copper ferrite, nickel-zinc ferrite, manganese-magnesium ferrite, copper-magnesium ferrite, manganese-zinc ferrite, Manganese-copper-zinc ferrite and the like can be mentioned.

These ferrite particles can be produced by a known method. For example, ferrite raw materials such as Fe ₂ O ₃ and Mg (OH) ₂ are mixed, and this mixed powder is heated in a heating furnace and calcined. After the obtained calcined product is cooled, it is pulverized with a vibration mill so as to have particles of approximately 1 μm, and a dispersant and water are added to the pulverized powder to prepare a slurry. The slurry is wet pulverized with a wet ball mill, and the resulting suspension is granulated and dried with a spray dryer to obtain ferrite particles.

  A known resin material can be used as the coating material constituting the coating layer of the carrier, and examples thereof include an acrylic resin and a silicone resin. In particular, a coated carrier coated with a silicone resin, that is, a coated carrier having a silicone resin coating layer is preferable. When a coated carrier having a silicone resin coating layer is used, toner components such as a crystalline polyester resin and a release agent are less likely to adhere to the surface of the carrier, thereby suppressing carrier contamination and excellent charging stability.

  A well-known thing can be used as a silicone resin. Moreover, the silicone resin is marketed, for example with the form of a varnish, and these can be used conveniently. Specific examples include silicone varnish (manufactured by Toshiba Corporation: TSR115, TSR114, TSR102, TSR103, YR3061, TSR110, TSR116, TSR117, TSR108, TSR109, TSR180, TSR181, TSR187, TSR144, TSR165, manufactured by Shin-Etsu Chemical Co., Ltd .: KR271, KR272, KR275, KR280, KR282, KR267, KR269, KR211, KR212), alkyd-modified silicone varnish (manufactured by Toshiba Corporation: TSR184, TSR185), epoxy-modified silicone varnish (manufactured by Toshiba Corporation: TSR194, YS54), polyester Resin-modified silicone varnish (Toshiba Corporation: TSR187), acrylic-modified silicone varnish (Toshiba Corporation: TSR) 70, TSR171), urethane-modified silicone varnish (manufactured by Toshiba Corporation: TSR175), reactive silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd .: KA1008, KBE1003, KBC1003, KBM303, KBM403, KBM503, KBM602, KBM603) and the like. .

  In order to control the volume resistivity value of the carrier, a conductive material is preferably added to the covering material. Examples of the conductive material include silicon oxide, alumina, carbon black, graphite, zinc oxide, titanium black, iron oxide, titanium oxide, tin oxide, potassium titanate, calcium titanate, aluminum borate, magnesium oxide, barium sulfate, Examples thereof include calcium carbonate. Among these conductive materials, carbon black is preferable from the viewpoint of production stability, cost, and low electrical resistance. The type of carbon black is not particularly limited, but a carbon black having a DBP (dibutyl phthalate) oil absorption in the range of 90 to 170 ml / 100 g is preferable in terms of excellent production stability. In addition, particles having a primary particle size of 100 nm or less are particularly preferable because of excellent dispersibility. These conductive materials may be used alone or in combination of two or more. It is preferable that the addition amount of a electrically conductive material is 0.1-20 mass parts with respect to 100 mass parts of coating | covering materials.

  In order to coat the carrier particles with the coating material, a known method can be employed. For example, an immersion method in which carrier particles are immersed in an organic solvent solution of the coating material, a spray method in which the organic solvent solution of the coating material is sprayed on the carrier particles, an organic solvent solution of the coating material in a state where the carrier particles are suspended by flowing air And a kneader coater method in which carrier particles and an organic solvent solution of a coating material are mixed in a kneader coater to remove a solvent such as an organic solvent. Here, the organic solvent solution of the covering material preferably contains a conductive material.

[Physical property measurement method]
Below, the measuring method of each physical-property value regarding this invention is demonstrated.

{Surface presence rate}
The surface abundance ratio of the titanium oxide fine particles is defined as follows.
The true specific gravity of the toner is “ρ ₁ ”, the primary particle diameter is “r ₁ (μm)”, the true specific gravity of the titanium oxide fine particles is “ρ ₂ ”, the primary particle diameter is “r ₂ (μm)”, and fluorescent X-ray When the Ti strength (kcps) of the material is “X _t ”, the surface abundance ratio is expressed by the following equation.
Surface abundance ratio = (X _t / 100) × (ρ ₁ / ρ ₂ ) × (r ₁ / r ₂ )
In addition, the measuring method of Ti intensity | strength in a fluorescent X ray and a primary particle diameter is as mentioning later. The true specific gravity of the toner is “ρ ₁ = 1.0”, and the true specific gravity of the titanium oxide is “ρ ₂ = 4.0”.

{Built-in state}
The method for measuring the buried state is as follows.
When the value of “Ti adhesion strength” calculated from the following formula is 95% or more, it is defined as being buried.
Ti adhesion strength = (X-ray fluorescence intensity after treatment) / (X-ray fluorescence intensity before treatment) x 100 [wt%]
The treatment in the above formula is the ultrasonic treatment described below.
Weigh 2.0 g of toner in a 100 ml beaker and add 40 ml of 0.2 wt% triton aqueous solution. After stirring for 1 minute with a stirrer to wet the toner, the external additive is removed using an ultrasonic homogenizer under the conditions of an output of 40 μA for 4 minutes. Thereafter, the mixture is allowed to stand for 3 hours to separate the toner and the external additive, and then the supernatant liquid is removed, 50 ml of pure water is added to the precipitate, the mixture is stirred for 5 minutes with a stirrer, and suction filtered using a membrane filter having a diameter of 1 μm. Vacuum drying is performed for 24 hours with a desiccator containing silica gel, and the obtained sample is used as a processed sample.

{Fluorescent X-ray}
In an X-ray fluorescence analyzer (trade name: ZSX / Primus II, manufactured by Rigaku Corporation), the target of the X-ray source is Rh, the applied voltage to the X-ray source is 40 kV, the current value is 50 mA, and the optical system is used as a spectral crystal. LiF (target: Si) or pentaerythritol (PET, target: Fe) was used. In addition, a scintillation counter and a photo counter are used for the detector, and the spectroscope is scanned using the skip scan method, the PHA range is set to 100 to 300, and the angle is set to 0.05 degree per step. X-ray intensity was measured. As a toner sample, 1 g was pelletized to obtain a measurement sample.

{Primary particle size}
In the present invention, the primary particle diameter of the titanium oxide fine particles and the external additive is obtained by photographing particles using a scanning electron microscope (SEM), and arbitrarily setting the particle diameter (major diameter) of 100 particles from the obtained image. The average value of 100 particle diameters is measured, and this is used as the primary particle diameter.

{Hydrophobic rate}
In the present invention, the hydrophobicity can be measured by the following method.
Weigh 1 g of titanium oxide fine particle sample in a 200 mL separatory funnel, add 100 mL of pure water to this, plug it, shake with a tumbler mixer for 10 minutes at 90 rpm, leave it for 10 minutes after shaking. To do. After standing, 20 to 30 mL of the lower layer mixed solution is extracted from the funnel, the lower layer mixed solution is taken into a 10 mm quartz cell, and a light transmittance (%) with a pure water as a blank using a colorimeter is used (%). ) Is the hydrophobic rate (%).

{Loss on drying}
In the present invention, the loss on drying can be measured by the following method.
The mass (A) of the sufficiently dried weighing bottle is measured, and the mass (B) of the titanium oxide fine particles placed on the weighing bottle is measured. The weighing bottle and the titanium oxide fine particles are dried at 105 ° C. for 2 hours with a constant temperature dryer, and then transferred to a desiccator and allowed to cool for 15 minutes. The mass (C) of the weighing bottle and the titanium oxide fine particles after being allowed to cool is measured, and the loss on drying (% by mass) is calculated by the following formula (2).
Loss on drying (% by mass) = {(BC) / (BA)} × 100 (2)

{Molecular weight of resin}
In the present invention, the molecular weight [peak top molecular weight (Mp) and number average molecular weight (Mn)] of the polyester resin is measured under the following conditions using gel permeation chromatography (GPC). For the measurement of molecular weight, a polyester resin is dissolved in THF, and the insoluble matter is filtered off with a glass filter, and used as a sample solution. The peak top molecular weight refers to a molecular weight showing the maximum peak height in a chromatogram obtained by GPC measurement.
Device (example): HLC-8120 manufactured by Tosoh Corporation
Column (example): TSK GEL GMH6 2 [Tosoh Corp.]
Measurement temperature: 40 ° C
Sample solution: 0.25 wt% THF (tetrahydrofuran) solution Solution injection amount: 100 μl
Detection apparatus: Refractive index detector Reference material: Tosoh standard polystyrene (TSK standard POLYSYRENE) 12 points (molecular weight 500 1050 2800 5970 9100 18100 37900 96400 190000 355000 1090000 2890000)

{Acid value and hydroxyl value of resin}
In the present invention, the acid value and hydroxyl value of the polyester resin are values measured by a method defined in JIS K0070 (1992 edition). In addition, when the sample has a solvent-insoluble component accompanying crosslinking, a sample after melt kneading is used as a sample by the following method.
Kneading device: Labo plast mill MODEL4M150 manufactured by Toyo Seiki Co., Ltd.
Kneading conditions: 130 ° C., 70 rpm, 30 minutes

{SP value}
In the present invention, the SP value is calculated by the method described in “POLYMER ENGINEERING AND SCIENCE, FEBRUARY, 1974, Vol. 14, No. 2, ROBERT F. FEDORS. (Pp. 147 to 154)” proposed by Fedors et al. Is done.

{Melting point}
Using a differential scanning calorimeter (for example, DSC210, manufactured by Seiko Denshi Kogyo Co., Ltd.), the sample to be measured was heated to 200 ° C. and then cooled to 0 ° C. at a temperature decreasing rate of 10 ° C./min. The temperature is increased at a rate of 1 minute / minute, and the endothermic change is measured. A graph of “endothermic amount” and “temperature” is drawn, and the temperature corresponding to the maximum peak of the endothermic amount is defined as the melting point (Tmp).

{Softening point}
Using a flow tester (trade name: CFT-100C, manufactured by Shimadzu Corporation), a 1 g measurement sample was heated at a heating rate of 6 ° C./min. , Extrude from a nozzle with a length of 1 mm, draw a graph of "plunger descent amount (flow value)" and "temperature", and read the temperature corresponding to 1/2 of the maximum value of plunger descent amount from the graph This value (temperature when half of the measurement sample flows out) is defined as a softening point (Tm).

{Glass-transition temperature}
In accordance with Japanese Industrial Standard (JIS) K7121-1987, a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.) was used to heat 1 g of a sample at a heating rate of 10 ° C. per minute to obtain a DSC curve. taking measurement. Draw the endothermic peak corresponding to the glass transition of the obtained DSC curve at a point where the slope is maximum with respect to the straight line that extends the base line on the high temperature side to the low temperature side and the curve from the rising part of the peak to the vertex. The temperature at the intersection with the tangent is defined as the glass transition temperature (Tg).

{Volume average particle diameter of toner}
To 50 ml of electrolyte (trade name: ISOTON-II, manufactured by Beckman Coulter, Inc.), 20 mg of toner particles and 1 ml of sodium alkyl ether sulfate are added, and an ultrasonic disperser (trade name: UH-50, manufactured by SMT Corporation). Was used for dispersion treatment at an ultrasonic frequency of 20 kHz for 3 minutes to prepare a measurement sample. The sample for measurement is measured using a particle size distribution measuring device (trade name: Coulter Multisizer II, manufactured by Beckman Coulter, Inc.) under the conditions of an aperture diameter of 100 μm and the number of measured particles of 50000 counts. The volume average particle diameter of the toner was determined from the particle size distribution.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Preparation of titanium oxide fine particles S1)
While maintaining a 300 g / liter aqueous solution of titanium tetrachloride as a titanium oxide raw material at room temperature, an aqueous sodium hydroxide solution having a concentration of 300 g / liter is added to adjust the pH to 7.0, thereby colloidal amorphous hydroxylation. Titanium was deposited and subsequently aged for 4 hours at a temperature of 65 ° C. to obtain a fine titania sol having a rutile nucleus.
The above microtitania sol is made into a microtitania sol having a rutile nucleus at a concentration of 50 g / liter, 1 liter of this is adjusted to pH 3 with sulfuric acid, n-hexyltrimethoxysilane is added, and the temperature is raised to 60 ° C. over 1 hour. By heating, n-hexyltrimethoxysilane was coated on the surface of titanium dioxide by 8% by weight with respect to titanium oxide. Thereafter, filtration and washing were performed, and the obtained wet cake was heat-treated at 120 ° C. for a whole day and night to obtain rutile ultrafine titanium dioxide having a particle diameter of 60 nm.

(Preparation of titanium oxide fine particles S2)
While maintaining a 200 g / liter aqueous solution of titanium tetrachloride as a titanium oxide raw material at room temperature, an aqueous sodium hydroxide solution having a concentration of 200 g / liter is added to adjust the pH to 7.0, thereby colloidal amorphous hydroxylation. Titanium was deposited and subsequently aged for 4 hours at a temperature of 65 ° C. to obtain a fine titania sol having a rutile nucleus.
The above microtitania sol is made into a microtitania sol having a rutile nucleus at a concentration of 50 g / liter, 1 liter of this is adjusted to pH 3 with sulfuric acid, n-hexyltrimethoxysilane is added, and the temperature is raised to 60 ° C. over 1 hour. By heating, n-hexyltrimethoxysilane was coated on the surface of titanium dioxide by 8% by weight with respect to titanium oxide. Thereafter, filtration and washing were performed, and the obtained wet cake was heat-treated at 120 ° C. for a whole day and night to obtain rutile ultrafine titanium dioxide having a particle diameter of 20 nm.

(Preparation of titanium oxide fine particles S3)
While maintaining a 300 g / liter aqueous solution of titanium tetrachloride as a titanium oxide raw material at room temperature, an aqueous sodium hydroxide solution having a concentration of 300 g / liter is added to adjust the pH to 7.0, thereby colloidal amorphous hydroxylation. Titanium was precipitated and subsequently aged for 24 hours at a temperature of 55 ° C. to obtain a fine titania sol having a rutile nucleus.
The above microtitania sol is made into a microtitania sol having a rutile nucleus at a concentration of 50 g / liter, 1 liter of this is adjusted to pH 3 with sulfuric acid, n-hexyltrimethoxysilane is added, and the temperature is raised to 60 ° C. over 1 hour. By heating, n-hexyltrimethoxysilane was coated on the surface of titanium dioxide by 8% by weight with respect to titanium oxide. Thereafter, filtration and washing were performed, and the obtained wet cake was heat-treated at 120 ° C. for a whole day and night to obtain rutile ultrafine titanium dioxide having a particle diameter of 100 nm.

(Preparation of titanium oxide fine particles S4)
A part of the fine titania sol used for the preparation of rutile-type ultrafine titanium dioxide having a particle diameter of 20 nm was collected, separated, washed, and then heat treated at a temperature of 120 ° C. to obtain finely hydrated titanium oxide. Furthermore, it was heat-treated in the atmosphere at a temperature of 120 ° C. for 3 hours to obtain rutile type ultrafine particle titanium dioxide having a particle diameter of 10 nm.

(Preparation of titanium oxide fine particles S5)
Part of the fine titania sol used for the preparation of rutile-type ultrafine titanium dioxide having a particle diameter of 100 nm was collected, separated, washed, and then heat treated at a temperature of 120 ° C. to obtain finely hydrated titanium oxide. Furthermore, it was heat-treated in the atmosphere at a temperature of 120 ° C. for 3 hours to obtain rutile type ultrafine particle titanium dioxide having a particle diameter of 200 nm.

(Preparation of amorphous polyester resin PA1)
In the reaction tank, 440 g (2.7 mol) of terephthalic acid, 235 g (1.4 mol) of isophthalic acid, 7 g (0.05 mol) of adipic acid, 554 g (8.9 mol) of ethylene glycol, and tetrabutoxy as a polymerization catalyst. After adding 0.5 g of titanate and reacting for 5 hours while distilling off the water and ethylene glycol produced at 210 ° C. under a nitrogen stream, the reaction was carried out for 1 hour under reduced pressure of 5 to 20 mmHg. Next, 103 g (0.54 mol) of trimellitic anhydride was added and reacted for 1 hour under normal pressure, then reacted under reduced pressure of 20 to 40 mmHg, and the resin was taken out at a predetermined softening point. The recovered ethylene glycol was 219 g (3.5 mol). The obtained resin was cooled to room temperature and then pulverized into particles. This was designated as amorphous polyester resin PA1. Amorphous polyester resin PA1 had a Tg of 56 ° C., a Tm of 135 ° C., an Mp of 4800, an acid value of 37 mgKOH / g, and a hydroxyl value of 50 mgKOH / g.

(Preparation of amorphous polyester resin PA2)
In the reaction vessel, terephthalic acid 310 g (1.9 mol), isophthalic acid 465 g (2.8 mol), adipic acid 36 g (0.25 mol), ethylene glycol 610 g (9.8 mol), tetrabutoxy as a polymerization catalyst. After adding 0.5 g of titanate and reacting for 5 hours while distilling off the water and ethylene glycol produced at 210 ° C. under a nitrogen stream, the reaction was carried out for 1 hour under reduced pressure of 5 to 20 mmHg. Next, 52 g (0.27 mol) of trimellitic anhydride was added and reacted under normal pressure for 1 hour, and then reacted under reduced pressure of 20 to 40 mmHg to take out the resin at a predetermined softening point. The recovered ethylene glycol was 262 g (4.2 mol). The obtained resin was cooled to room temperature and then pulverized into particles. This was designated as amorphous polyester resin PA2. Amorphous polyester resin PA2 had a Tg of 60 ° C., a Tm of 150 ° C., an Mp of 10,500, an acid value of 10 mgKOH / g, and a hydroxyl value of 0 mgKOH / g.

(Preparation of crystalline polyester resin PC1)
In a reaction vessel, 132 g (1.12 mol) of 1,6-hexanediol, 230 g (1.0 mol) of 1,10-decanedicarboxylic acid, and 3 g of tetrabutoxy titanate as a polymerization catalyst were added at 210 ° C. under normal pressure. The reaction was carried out for 5 hours while distilling off the water produced. Subsequently, the reaction was continued under a reduced pressure of 5 to 20 mmHg, and the resin was taken out when the acid value became 2 mgKOH / g or less. The obtained resin was cooled to room temperature and then pulverized into particles. This was designated as crystalline polyester resin PC1. The crystalline polyester resin PC1 had a Tmp of 66 ° C., a Tm of 73 ° C. (Tm / Tmp = 1.1), and an Mp of 13500.

(Preparation of crystalline polyester resin PC2)
In a reactor, 132 g (1.12 mol) of 1,6-hexanediol, 343 g (1.0 mol) of 1,18-octadecanedicarboxylic acid, and 3 g of tetrabutoxy titanate as a polymerization catalyst were added at 210 ° C. under normal pressure. The reaction was carried out for 5 hours while distilling off the water produced. Subsequently, the reaction was continued under a reduced pressure of 5 to 20 mmHg, and the resin was taken out when the acid value became 2 mgKOH / g or less. The obtained resin was cooled to room temperature and then pulverized into particles. This was designated as crystalline polyester resin PC2. Crystalline polyester resin PC2 had Tmp of 68 ° C., Tm of 95 ° C. (Tm / Tmp = 1.4), and Mp of 20000.

[Example 1]
(Preparation of Toner T1)
Amorphous polyester resin PA1 80 parts by weight Crystalline polyester resin PC1 20 parts by weight Wax (WEP-5, manufactured by NOF Corporation) 5 parts by weight Carbon black (MA-100, manufactured by Mitsubishi Chemical Corporation) 7 parts by weight Charge control agent ( Bontron E84, manufactured by Orient Chemical Co., Ltd.) 1 part by mass The above toner raw material was stirred and mixed for 5 minutes with a Henschel mixer (FM20C, manufactured by Nippon Coke Co., Ltd.), and the resulting stirred mixture was mixed with an open roll type continuous kneader (MOS320-1800, (Mitsui Mining Co., Ltd.).

  The obtained melt-kneaded product is cooled by a cooling belt, then coarsely pulverized using a speed mill having a φ2 mm screen, and then using a jet type pulverizer (IDS-2, manufactured by Nippon Pneumatic Industry Co., Ltd.). Finely pulverized and further classified using an elbow jet classifier (manufactured by Nippon Steel & Mining Co., Ltd., model: EJ-LABO) to obtain toner base particles having a volume average particle diameter of 6.5 μm.

  Next, to 100 parts by mass of the obtained toner base particles, 0.5 parts by mass of hydrophobic titanium oxide fine particles S1 as metal fine particles, commercially available silica fine particles (trade name: R976, manufactured by Aerosil, average primary particle diameter: 7 nm) Is added to the surface of the hydrophobic titanium oxide fine particles S1 by stirring for 2 minutes with an airflow mixer (Henschel mixer, manufactured by Mitsui Mining Co., Ltd.) with the tip speed of the stirring blade set to 40 m / sec. A toner T1 of Example 1 having a rate of 6% and a volume average particle diameter of 6.5 μm was produced. The Ti adhesion strength at that time was 98%.

[Examples 2 to 12 and Comparative Examples 1 to 4]
(Preparation of toners T2 to T16)
Example 2 to Example 12 having a volume average particle diameter of 6.5 μm and comparison were made in the same manner as the preparation of toner T1, except that the type of toner raw material and the hydrophobic titanium oxide fine particles were changed to those shown in Table 1. The toners T2 to T12 and T13 to T16 of Example 1 to Comparative Example 4 were prepared.
As a result, the surface abundance ratio of hydrophobic titanium oxide fine particles and the Ti adhesion strength of toners T1 to T16 were as follows.
Sample name: surface abundance ratio / adhesion strength T1: 6% / 98%
T2: 6% / 98%
T3: 6% / 98%
T4: 6% / 98%
T5: 18% / 99%
T6: 3.6% / 96%
T7: 6% / 98%
T8: 18% / 99%
T9: 3.6% / 96%
T10: 6% / 98%
T11: 18% / 99%
T12: 3.6% / 96%
T13: 6% / 98%
T14: 6% / 98%
T15: 36% / 100%
T16: 1.8% / 92%

(Preparation of carrier)
Ferrite particles (volume average particle size 45 μm) 100 parts by mass Toluene 15 parts by mass Silicone resin (number average molecular weight: about 15000) 2 parts by mass Carbon black (primary particle size 25 nm, oil absorption 150 ml / 100 g) 0.15 parts by mass Octyl acid 0.1 parts by mass The above materials excluding ferrite particles were stirred with a stirrer for 10 minutes to prepare a dispersed coating solution, and the coating solution and ferrite particles were placed in a vacuum degassing kneader at 60 ° C. After stirring for 25 minutes, the mixture was further depressurized while being heated, degassed, and dried, so that the volume average particle size was 45 μm, the coverage of the silicone resin was 100%, the volume resistivity was 2 × 10 ¹¹ Ω · cm, A carrier having a saturation magnetization of 65 emu / g was produced.

(Preparation of two-component developer D1)
The toner T1 (A) and the carrier (B) are charged into a Nauter mixer (trade name: VL-0, manufactured by Hosokawa Micron Corporation) at a mass ratio (A: B) of 6:94 and stirred and mixed for 20 minutes. Thus, a two-component developer D1 of Example 1 was produced.

(Preparation of two-component developers D2 to D10)
The two-component developers D2 of Examples 2 to 12 and Comparative Examples 1 to 4 were prepared in the same manner as the preparation of the two-component developer D1, except that the toners T2 to T16 were used instead of the toner T1. D12 and D13 to D16 were produced.

(Evaluation)
Low-temperature fixability of the produced toners T1 to T12 and T13 to T16 and two-component developers D1 to D12 and D13 to D16 of Examples 1 to 12 and Comparative Examples 1 to 4 according to the following evaluation method And the image sticking phenomenon was evaluated. The evaluation results are shown in Table 2.

(Evaluation method for low-temperature fixability)
The produced two-component developer and toner are filled in a developing device and a toner cartridge of a color composite machine (trade name: MX-2640, manufactured by Sharp Corporation), respectively, and the fixing roller temperature in the fixing device is 150 ° C. ± 1 ° C. And an image sample for fixing strength measurement was prepared in an environment with an air temperature of 20 ° C. and a humidity of 60%.

  As an image sample for fixing strength measurement, a document including a solid image portion (image density ID = 1.5) having a side of 3 cm is copied onto a recording paper (trade name: PPC paper SF-4AM3, manufactured by Sharp Corporation). Created by.

  The solid image portion of the image sample was folded inward, and in the folded state, an 850 g roller was rolled back and forth on the fold line at a constant pressure to produce a peel sample in which the toner image was peeled off at the folded portion.

The peeled sample was spread out and the peeled toner was blown off with an air brush, and the peel width (maximum white line width that can be formed in the bent portion) was measured as an index of fixing strength.
Evaluation criteria for low-temperature fixability are as follows.
○: Good. Peel width is less than 0.3 mm.
Δ: Slightly poor Peel width is 0.3 mm or more and less than 0.5 mm.
X: Defect. Peel width is 0.5mm or more.

(Evaluation method for image defects and developability)
The produced two-component developer and toner are filled in a developing device and a toner cartridge of a color composite machine (trade name: MX-2640, manufactured by Sharp Corporation), respectively, and the central portion and both end portions in the axial direction of the developing roller are filled. A continuous print test of 50,000 sheets was performed in an environment of 30 ° C. and 80% humidity so that a square solid image (ID = 1.45 to 1.50) having a side of 1 cm was formed at three positions.
The evaluation criteria for image defects such as fogging and rustling are as follows.

(Fog)
The whiteness of the non-image area of the recording paper printed using the life developer (developer after a continuous print test of 50000 sheets) was measured. The whiteness is determined as tristimulus values X, Y, and Z using an SZ90 spectroscopic color difference meter manufactured by Nippon Denshoku Industries Co., Ltd. .7 or less was acceptable, and when it was greater than 0.7, it was evaluated as defective.

(Gastsuki)
Using the above life developer, an image test chart is printed, and an automatic printer image quality evaluation system (product name: APQS, manufactured by Oji Scientific Instruments Co., Ltd.) is used to measure graininess when the color difference from white is 30, 50, 70. Was used to measure the granularity score value. The lower the graininess score value, the less the roughness of the image and the higher the image quality. Here, the maximum value of the score value of each color difference was evaluated as good when the value was less than 11500, the value between 12000 and 11500 was acceptable, and the value greater than 12000 was evaluated as defective.

The evaluation criteria for developability are as follows.
The image density of the image area of the recording paper printed using the above life developer was measured with an XRite 938 spectrocolorimetric densitometer. When the image density is 1.4 or more, it is evaluated as good, when it is 1.3 or more and less than 1.4, and when it is less than 1.3, it is evaluated as defective.

Claims (3)

In a toner including a binder resin including an amorphous polyester resin and a crystalline polyester resin, and an external additive,
The amorphous polyester resin has an SP value of 10.5 to 12.5 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 . An amorphous polyester resin,
The crystalline polyester resin is obtained by polycondensing a dicarboxylic acid monomer mainly containing an aliphatic dicarboxylic acid having 9 to 22 carbon atoms and a diol monomer mainly containing an aliphatic diol having 2 to 10 carbon atoms. A crystalline polyester resin having an SP value of 9.3 to 10.0 ,
The external additive includes hydrophobized titanium oxide fine particles having a primary particle diameter of 20 nm to 100 nm, and the titanium oxide fine particles are embedded in toner particles containing the binder resin, and A toner having a surface presence ratio of titanium oxide fine particles of 2 to 20%.   The toner according to claim 1, wherein the hydrophobic treatment is performed with hexamethyldisilazane, and the hydrophobicity of the hydrophobized titanium oxide fine particles is 95% or more and 100% or less.   A two-component developer comprising the toner according to claim 1 and a carrier.