JP2015031915A - Additive for toner, and toner for electrostatic charge image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive for a positively-charged toner that can improve the negative chargeability of a negatively-charged toner.SOLUTION: An additive for toner of the present invention contains resin particles having a surface layer formed at least of an amino-based resin, and a hydrophobic inorganic oxide, where a content ratio of the hydrophobic inorganic oxide is 0.05 parts by weight to 10 parts by weight relative to 100 parts by weight of the resin particles; an average particle diameter of the resin particles is 780 nm or less; an average particle diameter of the hydrophobic inorganic oxide is 80 nm or less; and a hydrophobicity of the hydrophobic inorganic oxide is 45% or more.

Description

  The present invention relates to a toner additive and an electrostatic charge image developing toner.

  In electrophotography, an electrostatic charge image is formed on the surface of the photoconductor, and a developer containing toner charged to the opposite charge is contacted on the electrostatic charge image, and the toner adheres and is visible. Form an image. The visualized toner image is transferred to a transfer paper or the like as necessary, and then fixed to form a copy.

  Generally, an additive is added to the toner in order to improve its chargeability. A manufacturer who manufactures a plurality of toners needs to prepare a plurality of additives according to the type of toner to be manufactured. For example, at least two types of additives must be prepared according to the chargeability of the toner. There is a need to. Specifically, for the production of a positively chargeable toner, it is necessary to prepare a positively chargeable additive for improving the chargeability of the toner, while for the production of a negatively chargeable toner. Therefore, it is necessary to prepare a negatively chargeable additive. Such a situation is a factor that complicates material management and process management when manufacturing a plurality of toners.

JP 2012-13776 A JP 2012-73468 A

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a positively chargeable toner additive capable of improving the negative chargeability of a negatively chargeable toner. There is to do.

The additive for toner of the present invention contains at least a resin particle whose surface layer is formed of an amino resin and a hydrophobic inorganic oxide, and the content ratio of the hydrophobic inorganic oxide is 100 parts by weight of the resin particle. On the other hand, it is 0.05 to 10 parts by weight, the average particle size of the resin particles is 780 nm or less, the average particle size of the hydrophobic inorganic oxide is 80 nm or less, and the hydrophobic inorganic The degree of hydrophobicity of the oxide is 45% or more.
In one embodiment, the hydrophobic inorganic oxide is hydrophobic silica, hydrophobic titania, hydrophobic alumina, hydrophobic zirconia, hydrophobic zinc oxide, hydrophobic tin oxide or hydrophobic tantalum oxide.
In one embodiment, the resin particles have a core-shell structure having a core layer and a shell layer, and the shell layer is formed from an amino resin.
According to another aspect of the present invention, a toner for developing an electrostatic image is provided. The toner for developing an electrostatic image includes the toner additive.
In one embodiment, the electrostatic image developing toner of the present invention further includes toner particles, and the content ratio of the toner additive is 0.05 parts by weight to 100 parts by weight of the toner particles. 1 part by weight.

  According to the present invention, it is possible to provide a toner additive capable of improving the negative chargeability of a negatively chargeable toner while being a toner additive having a positive chargeability.

  More specifically, since the toner additive of the present invention has a positive chargeability, it can be used as a toner additive for improving the chargeability of a positively chargeable toner, and further, as described above, a negative chargeability. Even with this toner, the effect of improving the chargeability (improvement of negative chargeability) is exhibited.

A. Toner Additive The toner additive of the present invention includes resin particles having at least a surface layer formed of an amino resin and a hydrophobic inorganic oxide. The resin particles have an average particle size of 780 nm or less. The hydrophobic inorganic oxide has an average particle size of 80 nm or less and a degree of hydrophobicity of 45% or more. The toner additive of the present invention has a positive chargeability.

  The content of the hydrophobic inorganic oxide is 0.05 parts by weight to 10 parts by weight, more preferably 0.1 parts by weight to 9.0 parts by weight, with respect to 100 parts by weight of the resin particles. Preferably they are 0.3 weight part-8.0 weight part. If the content ratio of the hydrophobic inorganic oxide is in such a range, a toner additive capable of improving the chargeability of the toner can be obtained for a negatively chargeable toner. The toner additive of the present invention can exhibit an effect of improving the chargeability not only for positively chargeable toners but also for negatively chargeable toners. When the content of the hydrophobic inorganic oxide is less than 0.1 parts by weight or more than 10 parts by weight, the conventional effect as a positively chargeable additive, that is, charging of a positively chargeable toner is achieved. Only the effect of improving the property can be obtained.

  In one embodiment, at least a part of the hydrophobic inorganic oxide contained in the toner additive of the present invention adheres to the surface of the resin particles. The amount of the hydrophobic inorganic oxide attached to the resin particle surface is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the resin particles. In other words, it is preferable that 10 wt% to 100 wt% of the hydrophobic inorganic oxide is attached to the resin particles with respect to the total amount of the hydrophobic inorganic oxide contained in the toner additive of the present invention.

  When the hydrophobic inorganic oxide adheres to the resin particles, the hydrophobic inorganic oxide does not need to form a layer. That is, the hydrophobic inorganic oxide may be attached in the form of dots or in the form of layers. Preferably, it adheres in the form of dots. Further, the hydrophobic inorganic oxide may be attached in a state of being embedded in the resin particles.

A-1. Resin Particles The average particle diameter of the resin particles is 780 nm or less, preferably 20 nm to 780 nm, more preferably 30 nm to 600 nm, still more preferably 30 nm to 500 nm, and particularly preferably 30 nm to 200 nm. . Within such a range, it is possible to obtain a toner additive that does not easily fall off from the surface of the toner particles. In addition, the average particle diameter of the resin particles is calculated by measuring the diameter (maximum length of the particles (cross section)) of a predetermined number of particles selected at random and calculating the arithmetic average thereof. Details of the average particle size evaluation method will be described later.

  As described above, at least the surface layer of the resin particles is formed from an amino resin. A positively chargeable toner additive can be obtained by a combination of the resin particles and the hydrophobic inorganic oxide. In addition, if resin particles whose surface layer is formed of an amino resin are used, an additive for toner that exhibits an effect of improving chargeability with respect to negatively chargeable toner can be obtained.

  The resin particles may be formed only from an amino resin, or may have a core-shell structure in which the shell layer is formed from an amino resin.

  As said amino resin, the condensate of an amino compound and formaldehyde is mentioned, for example. As an amino compound, urea, thiourea, a polyfunctional amino compound etc. are mentioned, for example. Of these, polyfunctional amino compounds are preferably used, and polyfunctional amino compounds having a triazine-returned structure are more preferably used. Examples of the polyfunctional amino compound having a triazine ring structure include melamine; an amino compound represented by the general formula (1); a diaminotriazine compound represented by the general formula (2) or the general formula (3); And guanamine compounds such as cyclohexanecarboguanamine, cyclohexenecarboguanamine, acetoguanamine, norbornenecarboguanamine, and spiroguanamine. Among these, melamine and benzoguanamine are preferable. Only 1 type may be used for an amino compound and 2 or more types may be used for it.

Formula (1), R ^1, identical or different, represent an alkyl group which may be a hydrogen atom or a substituent, at least one of R ¹ is an alkyl group which may have a substituent. In general formula (1), R ¹ is preferably a hydrogen atom or a hydroxyalkyl group.

In General Formula (2), R ² is the same or different, and is a hydrocarbon group having 1 to 2 carbon atoms (—CH ₂ —, —CH ₂ CH ₂ —, —, which is a linear structure or a structure having a side chain. CH _(CH 3) -) is.

In general formula (3), R ³ is any one of a linear structure, a structure having a side chain, a structure having an aromatic ring which may have a substituent, and a structure having an alicyclic ring which may have a substituent. It is a C1-C8 hydrocarbon group which is. The structure having an aromatic ring or the structure having an alicyclic ring may be a structure having a side chain.

  In one embodiment, 10% to 100% by weight of the amino compound is a guanamine compound. The content ratio of the guanamine compound in the amino compound is preferably 20% by weight to 100% by weight, more preferably 40% by weight to 100% by weight, and further preferably 50% by weight to 100% by weight. More preferably 60% to 100% by weight, still more preferably 70% to 100% by weight, still more preferably 80% to 100% by weight, and still more preferably 90% to 100% by weight. More preferably, it is 95 to 100% by weight, and most preferably 100% by weight. Within such a range, it is possible to obtain a toner additive capable of preventing fogging and image density reduction.

  When the resin particles are formed only from an amino resin, the resin particles can be obtained by reacting the amino compound with formaldehyde (addition condensation reaction) by any appropriate method. Examples of a method for producing resin particles formed from an amino resin include, for example, JP 2000-256432 A, JP 2002-293854 A, JP 2002-293855 A, JP 2002-293856 A, and the like. JP 2002-293857, JP 2003-55422, JP 2003-82049, JP 2003-138823, JP 2003-147039, JP 2003-171432, JP 2003. And the production methods described in JP-A-176330, JP-A-2005-97575, JP-A-2007-186716, JP-A-2008-101040, and the like. Specifically, for example, the above-mentioned amino compound (preferably a polyfunctional amino compound) and formaldehyde are preferably subjected to an addition condensation reaction in a basic aqueous medium to form a condensate oligomer, and the condensate oligomer is dissolved. Alternatively, resin particles formed from an amino resin having a crosslinked structure can be produced by mixing and curing an acid catalyst such as dodecylbenzenesulfonic acid or sulfuric acid in an aqueous medium to be dispersed. It is preferable that both the step of generating the condensate oligomer and the step of forming the amino resin particles having a crosslinked structure are performed in a state of being heated at a temperature of 50 ° C to 100 ° C. In order to control the particle diameter of the amino resin crosslinked particles, the step of obtaining crosslinked amino resin particles is preferably performed in the presence of a surfactant. In addition, after the said hardening, you may obtain resin particles through processes, such as the aggregation process which aggregates particle | grains by arbitrary appropriate methods, a solid-liquid separation process, a particle | grain drying process, a grinding | pulverization process.

  When the resin particles have a core-shell structure, the resin particles are, for example, dispersed in the basic aqueous medium in the form of a core layer, and the amino compound and formaldehyde are dispersed in the aqueous medium as described above. It can be obtained by producing a condensate oligomer and further curing the condensate oligomer as described above.

  When the resin particles have a core-shell structure, the average particle size of the particles that form the core layer is preferably 10 nm to 700 nm, more preferably 20 nm to 400 nm, and still more preferably 30 nm to 150 nm.

  When the resin particles have a core-shell structure, the total thickness of the shell layer is preferably 10% or more, more preferably 15% to 500%, with respect to the average particle diameter of the particles serving as the core layer. It is preferably 20% to 400%, particularly preferably 30% to 350%.

  Any appropriate material can be selected as a material for forming the core layer. An organic material or an inorganic material may be used as a material constituting the core layer particles.

  Examples of the organic material forming the core layer include vinyl polymer fine particles. As the vinyl polymer fine particles, polymer fine particles obtained by using any appropriate polymerizable monomer and any appropriate crosslinkable monomer as required can be adopted.

  The polymerizable monomer may be a compound containing at least one ethylenically unsaturated group in the molecule. Specifically, for example, monomers having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate; methoxypolyethylene glycol (meth) acrylate Monomers having a polyethylene glycol component such as, butyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, isoamyl acrylate, lauryl (meth) acrylate, benzyl methacrylate, methacryl Alkyl (meth) acrylates such as acid tetrahydrofurfuryl; trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, pentanefluoropropyl (meth) acrylate, octafluoroamyl (meth) acrylate, etc. Fluorine atom-containing (meth) acrylates; aromatic vinyl compounds such as styrene, α-methylstyrene, vinyl tolman, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-ethylstyrene; glycidyl (Meth) acrylate; (meth) acrylic acid; (meth) acrylamide; (meth) acrylonitrile; The said polymerizable monomer may be used independently and may use 2 or more types together.

  Examples of the crosslinkable monomer include divinylbenzene, (poly) ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meta) ) Acrylate, tetramethylol methane tri (meth) acrylate, tetramethylolpropane tetra (meth) acrylate, dipentaerythritol hexaacrylate, diallyl phthalate and isomers thereof, triallyl isocyanurate and derivatives thereof, and the like. The said crosslinkable monomer may be used independently and may use 2 or more types together.

  Examples of the inorganic material forming the core layer include silica fine particles such as silicon alkoxide hydrolyzed condensate fine particles and sodium silicate hydrolyzed condensate fine particles.

  An organic-inorganic composite material may be used as a material for forming the core layer. Typically, the organic-inorganic composite material includes organic-inorganic composite fine particles containing polysiloxane as an inorganic component and a vinyl polymer as an organic component. The polysiloxane as the inorganic component is preferably a polysiloxane skeleton obtained by hydrolysis and condensation of an inorganic compound raw material containing a silicon compound having a (meth) acryloxy group.

Any appropriate form can be adopted as the form of the organic-inorganic composite fine particles. Specifically, for example,
a) A form in which polysiloxane, which is an inorganic component, is fine particles and dispersed in a vinyl polymer that is an organic component,
b) Form of core-shell structure in which polysiloxane as an inorganic component is a fine core particle, and a shell made of a vinyl polymer as an organic component is formed on the surface of the core particle;
c) a form of a core-shell structure in which a vinyl polymer as an organic component is a fine core particle, and a shell made of polysiloxane as an inorganic component is formed on the surface of the core particle;
d) A form in which polysiloxane as an inorganic component and vinyl polymer as an organic component are combined or mixed at a molecular level,
e) The form of the core-shell structure in which the fine particles in the state of d) become core particles, and a shell made of polysiloxane as an inorganic component is formed on the surface of the core particles.
Etc.

  Preferable methods for producing the organic / inorganic composite fine particles include, for example, methods described in JP-A-8-81561 and JP-A-2003-183327.

  The shape of the organic-inorganic composite fine particles is not particularly limited, and specifically, for example, a spherical shape, a needle shape, a plate shape, a scale shape, a pulverized shape, an uneven shape, an eyebrows shape, a candy sugar shape, etc. The shape can be mentioned.

A-2. Hydrophobic inorganic oxide The toner additive of the present invention comprises a hydrophobic inorganic oxide. In the present invention, a positively chargeable toner additive can be obtained by adding a hydrophobic inorganic oxide to the resin particles. Further, the positively chargeable toner additive can improve the negative chargeability of the negatively chargeable toner.

  As the hydrophobic inorganic oxide, hydrophobic silica, hydrophobic titania, hydrophobic alumina, hydrophobic zirconia, hydrophobic zinc oxide, hydrophobic tin oxide or hydrophobic tantalum oxide is preferably used. Only one type of hydrophobic inorganic oxide may be used, or two or more types may be used. The hydrophobic inorganic oxide can be obtained, for example, by hydrophobizing a hydrophilic inorganic oxide by any appropriate hydrophobizing treatment. Examples of the hydrophobizing treatment include a method of treating with a hydrophobizing agent such as hexamethyldisilazane (HMDS), dimethyldichlorosilane, silicone oil, methyltriethoxysilane. Moreover, positive chargeability can also be added to an inorganic oxide by this hydrophobic treatment.

A commercially available product may be used as the hydrophobic inorganic oxide. Examples of commercially available products include “Aerosil RY200”, “Aerosil RX200”, “Aerosil RX300”, “Aerosil R972”, “AeroXide TiO ₂ T805”, “AeroXide Alu C805” manufactured by Aerosil Japan. .

  The hydrophobicity of the hydrophobic inorganic oxide is preferably 45% or more, more preferably 50% or more, still more preferably 60% or more, and particularly preferably 60% or more and less than 100%. When the hydrophobicity of the hydrophobic inorganic oxide is in such a range, a toner additive capable of improving the chargeability of the toner can be obtained for a negatively chargeable toner. The degree of hydrophobicity can be measured by a methanol titration method. That is, in this specification, “hydrophobic degree” means that 0.2 g of hydrophobic inorganic oxide is suspended on the surface of 50 ml of water, and methanol is added little by little while gently stirring the water. Yuki (dropped using a burette), based on the amount of methanol used when all the powder on the water surface is submerged in water, the percentage of methanol with respect to water + methanol. A more detailed measurement method for the degree of hydrophobicity will be described later.

  The average particle diameter of the hydrophobic inorganic oxide is 80 nm or less, preferably 50 nm or less, more preferably 5 nm to 40 nm. When the average particle diameter of the hydrophobic inorganic oxide is in such a range, a toner additive capable of improving the chargeability of the toner can be obtained for a negatively chargeable toner. The toner additive of the present invention can exhibit an effect of improving the chargeability not only for positively chargeable toners but also for negatively chargeable toners. When the average particle size of the hydrophobic inorganic oxide is larger than 80 nm, only the conventional effect as a positively chargeable additive can be obtained, that is, only the effect of improving the chargeability of the positively chargeable toner is exhibited. Can not. The average particle size of the hydrophobic inorganic oxide can be measured by the same method as the average particle size of the resin particles.

  The hydrophobic inorganic oxide is preferably a hydrophobic inorganic oxide (so-called hydrophobic fumed inorganic oxide) obtained by a gas phase method. If a hydrophobic fumed inorganic oxide having a small particle size and a uniform particle size is used, the effect of the present invention becomes remarkable.

  Examples of the method of adding the hydrophobic inorganic oxide to the resin particles include a method of mixing the hydrophobic inorganic oxide and the resin particles for a predetermined time using any appropriate mixer. When mixed for an appropriate mixing time, at least a part of the hydrophobic inorganic oxide can adhere to the resin particles. The mixing time can be set to any appropriate time depending on the amount of the hydrophobic inorganic oxide and the resin particles, the mixing method, and the like. The mixing time is preferably 30 seconds or more, more preferably 1 minute or more, still more preferably 5 minutes or more, and particularly preferably 10 minutes to 30 minutes. Hydrophobic inorganic oxides may be used for mixing in powder form. In some cases, the hydrophobic inorganic oxide may be crushed in advance to make it easier to mix, or mixed in a solvent dispersed state. You may use for. Examples of the solvent include polar organic solvents such as alcohol solvents, ketone solvents, and ester solvents. These polar organic solvents may be used alone or in combination of two or more. A mixed solvent of a polar organic solvent and water may be used. The dispersion concentration is, for example, 0.5% by weight to 20% by weight.

  Moreover, in the step of obtaining the resin particles, a hydrophobic inorganic oxide may be added and the hydrophobic inorganic oxide may be added to the resin particles. Specifically, in the method for producing resin particles described in the section A-1, after the condensate oligomer is cured, a dispersion of a hydrophobic inorganic oxide is introduced before or during the aggregation process. Thus, a hydrophobic inorganic oxide can be added to the resin particles. Also by such a method, at least a part of the hydrophobic inorganic oxide can adhere to the resin particles. Examples of the solvent used for the dispersion include alcohol solvents such as methanol. The dispersion concentration of the dispersion is, for example, 0.5% by weight to 20% by weight.

B. Toner for developing an electrostatic image The toner for developing an electrostatic image of the present invention may contain the additive for toner of the present invention and toner particles. The toner for developing an electrostatic image may further contain another additive as necessary. The toner particles may have positive chargeability or negative chargeability. Regardless of whether the toner particles are positively or negatively charged, the toner for developing an electrostatic image with improved chargeability can be obtained by adding the toner additive of the present invention.

  The content of the toner additive of the present invention is preferably 0.05 to 1 part by weight, more preferably 0.05 to 0.5 part by weight, based on 100 parts by weight of the toner particles. More preferably 0.1 to 0.4 parts by weight. Within such a range, the chargeability of negatively chargeable toner particles can be improved.

  The toner particles preferably include a binder resin agent and a colorant that serve as a binder. Examples of the binding resin agent include styrene polymers, (meth) acrylic acid polymers, (meth) acrylic acid ester polymers, polyolefin polymers, polyester polymers, polyurethane polymers, polyamide polymers, and epoxy polymers. Etc. These may be used alone or in combination of two or more. Examples of the colorant include carbon black, phthalocyanine pigments, azo pigments / dyes, nigrosine dyes, extender pigments, and the like. These may be used alone or in combination of two or more.

  The average particle diameter of the toner particles is preferably 1 μm to 25 μm, more preferably 3 μm to 20 μm.

  Examples of the other additive include an anti-offset agent, magnetic fine particles, a charge control agent, and a colorant. Examples of the offset inhibitor include polyolefin waxes such as low molecular weight polyethylene and polypropylene; paraffin wax; natural waxes such as carnauba wax; Examples of the magnetic fine particles include ferromagnetic metal powders such as iron, cobalt, and nickel; fine particles such as magnetite, hematite, and ferrite. These may be used alone or in combination of two or more. The colorant such as carbon black is preferably surface-modified by grafting with a hydrophilic polymer or a hydrophobic polymer in order to obtain high dispersibility in the toner particles.

  As a method for producing the toner for developing an electrostatic charge image of the present invention, any suitable method for producing a toner for developing an electrostatic charge image can be adopted as long as it contains the toner additive of the present invention. For example, various production methods such as a pulverization method, a suspension polymerization method, and an emulsion polymerization method can be employed. In addition, as a method for adding the toner additive of the present invention, it is preferable to adopt a so-called external addition form in which the toner is attached to or added to the surface portion of the toner particles.

  Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples. In the following, “parts by weight” may be simply referred to as “parts” for convenience.

[Average particle diameter of resin particles and hydrophobic inorganic oxide]
The average particle diameter of the resin particles and the hydrophobic inorganic oxide (and the inorganic oxide used in the comparative example) was measured by the following method.
SEM photograph (magnification: 100,000 times) in the imaging range where the total number of particles is about 200, the diameter of 100 particles randomly selected from the photographed particles (maximum of particle (cross section)) Length) was measured with calipers, and the arithmetic average was taken as the average particle size.

[Measurement of charge amount]
The charge amounts of the toner particles and the toner for developing an electrostatic image were measured under the following conditions.
Measuring device: Blow-off type electrification measuring machine (Kyocera Chemical Co., Ltd., TB-200)
Blow pressure: 0.1 MPas
Carrier: Ferrite carrier (F96-150 manufactured by Powder Tech Co., Ltd.)
Developer: Toner concentration 5% (9.5 g of carrier and 5 g of toner are carefully evaluated and placed in a 20 ml polyethylene container and mixed for 30 minutes at a rotation speed of 100 rpm)

(Measurement of hydrophobicity)
The degree of hydrophobicity of the hydrophobic inorganic oxide was measured by the following method.
A 200 ml glass beaker with a stirrer placed at the bottom was charged with 50 ml of deionized water, and 0.2 g of hydrophobic inorganic oxide was floated on the water surface, and then the stirrer was gently rotated for 5 minutes. Thereafter, the tip of the burette was submerged in the water in the beaker, and methanol was gradually introduced from the burette. 1 ml of methanol was introduced at intervals of 3 minutes. Methanol was continuously introduced until the total amount of hydrophobic inorganic oxide on the water surface was completely submerged in water (the state where the hydrophobic inorganic oxide floating on the water surface was lost), and the polymer particles were completely submerged in water. The amount of methanol introduced (ml) was measured and the degree of hydrophobicity was determined based on the following formula.
Hydrophobic degree (%) = 100 × (methanol introduction amount ml / (deionized water amount ml + methanol introduction amount ml))

[Production Example 1] Production of amino resin particles In a stainless steel reaction kettle equipped with a stirrer, thermometer, and cooler, 2620 parts of deionized water and 65 wt% sodium dodecylbenzenesulfonate (product of Kao Corporation, product) 10 parts of “Neopelex G65”) was added, the internal temperature was raised to 90 ° C. and maintained at the same temperature to prepare a sodium dodecylbenzenesulfonate aqueous solution.
On the other hand, 100 parts of melamine, 193 parts of 37% by weight formalin and 3 parts of 25% by weight ammonia water were added to another reaction kettle, the temperature was raised to 70 ° C., and maintained at that temperature for 30 minutes to prepare a reaction solution. . Then, this reaction liquid was thrown into the said sodium dodecylbenzenesulfonate aqueous solution hold | maintained at the said 90 degreeC. Next, 40 parts of a 10% by weight dodecylbenzenesulfonic acid aqueous solution was added, and the mixture was further aged at 80 ° C. to 90 ° C. for 5 hours to obtain a dispersion containing amino resin particles.
30 parts of a 10 wt% sulfuric acid band aqueous solution was added to 2066 parts of the obtained dispersion and stirred for 30 minutes. Thereafter, the dispersion was subjected to solid-liquid separation with a centrifuge, and the obtained cake was kept in a hot air dryer kept at 190 ° C. in a nitrogen atmosphere for 5 hours, dried, and then jet milled. Crushing by a pulverizer (pulverization pressure: 0.7 MPa) and airflow classification were performed to obtain amino resin particles (melamine resin particles; resin particles (1)). Table 1 shows the average particle diameter of the obtained amino resin particles.

[Production Examples 2 to 4] Production of amino resin particles 65% by weight of sodium dodecylbenzene sulfonate when preparing an aqueous solution of 65% by weight of sodium dodecylbenzene sulfonate (trade name “Neopelex G65” manufactured by Kao Corporation) Amino-based resin particles in the same manner as in Production Example 1 except that the blending amount, the temperature when preparing the aqueous solution of dodecylbenzenesulfonic acid and the blending amount of the 10 wt% aqueous solution of dodecylbenzenesulfonic acid were the conditions shown in Table 1. (Melamine resin particles; resin particles (2) to (4)) were obtained. Table 1 shows the average particle diameter of the obtained amino resin particles.

[Production Example 5] Production of core-shell type particles (shell layer: amino resin) (Production of core particles)
To a stainless steel reaction kettle equipped with a stirrer, thermometer, and cooler, add 820 parts of deionized water and 4 parts of 65 wt% sodium dodecylbenzenesulfonate (trade name “Neopelex G65” manufactured by Kao Corporation) The internal temperature was raised to 75 ° C. and kept at the same temperature to prepare a sodium dodecylbenzenesulfonate aqueous solution.
On the other hand, in a separate container, 140 parts of methyl methacrylate (hereinafter referred to as “MMA”) and 60 parts of divinylbenzene (81% by weight of active ingredient; hereinafter referred to as “DVB”) are mixed to obtain a monomer composition. 200 parts were prepared.
After replacing the inside of the reaction kettle with nitrogen gas, 20 parts of the monomer composition (10% by weight of the total amount of the monomer composition), 50 parts of 0.4% by weight of hydrogen peroxide water, and 0.4% by weight An initial polymerization reaction was carried out by adding 50 parts of a% L-ascorbic acid aqueous solution to the reaction kettle.
Subsequently, the remainder of the monomer composition (90% by weight of the total amount of the monomer composition) 180 parts, 450 parts by weight of 0.4% by weight hydrogen peroxide water, and 450 parts by weight of 0.4% by weight L-ascorbic acid aqueous solution Were dripped uniformly into the reaction kettle over 6 hours from different inlets. Thereafter, the internal temperature was raised to 90 ° C. and held at the same temperature for 6 hours for aging to obtain a core particle dispersion.
(Formation of shell layer)
800 parts of benzoguanamine (hereinafter referred to as “BG”), 1040 parts of 37% by weight formalin, 96 parts of 65% by weight DBSNa, 80 parts of dodecylbenzenesulfonic acid, and 10456 parts of ion-exchanged water were uniformly dispersed and mixed to obtain a BG dispersion. .
The BG dispersion was dropped into 2022.3 parts of the core particle dispersion held at 90 ° C. over 2 hours. After dropping, the mixture was further maintained at 90 ° C. for 5 hours, and then cooled to 30 ° C. to obtain a dispersion containing core-shell resin fine particles in which the surface of the core particles was coated with a condensate of BG and formaldehyde. When the average particle size and variation coefficient of the core-shell type resin fine particles in this dispersion were measured, the average particle size was 131 nm, and the variation coefficient was 5%.
160 parts of a 10% sulfuric acid band aqueous solution was added to 14494.3 parts of the dispersion containing the core-shell type resin fine particles, followed by stirring for 30 minutes. Thereafter, the dispersion is subjected to solid-liquid separation with a centrifugal separator, and the obtained cake is vacuum-dried at 190 ° C. for 5 hours, and then pulverized with a jet mill pulverizer (pulverization pressure: 0.7 MPa) and air flow classification. The core-shell type resin particles (resin particles (5)) in which the core layer was formed from a vinyl polymer and the shell layer was formed from an amino resin were obtained. Table 2 shows the average particle diameter of the obtained resin particles.

[Production Examples 6 and 7] Preparation of core-shell type particles (shell layer: amino-based resin) 65% by weight sodium dodecylbenzene sulfonate when preparing a 65% by weight sodium dodecylbenzene sulfonate aqueous solution (trade name, manufactured by Kao Corporation) Core-shell type resin particles (resin particles (6) and (7)) were obtained in the same manner as in Production Example 5 except that the blending amount of “Neopelex G65” was changed to the amount shown in Table 2. Table 2 shows the average particle diameter of the obtained resin particles.

[Production Example 8] Preparation of hydrophobic inorganic oxide (hydrophobic silica) In a stainless steel reaction kettle equipped with a stirrer, a thermometer, and a cooler, 101 parts of methanol, 15 parts of deionized water, 25% aqueous ammonia 20 The reaction vessel solution was prepared by uniformly stirring while keeping the internal temperature at 40 ° C.
To this reaction vessel liquid, 64 parts of methyl silicate was added with stirring at a feed rate of 5.3 ml / min to obtain a silica particle dispersion.
1 part of methyltrimethoxysilane was added to the obtained silica particle dispersion, the temperature was raised to the reflux temperature, and the reaction was carried out for 1 hour, followed by cooling.
Hydrophobized silica particle dispersion was spray-dried using a spray dryer (trade name “Spray Dryer SD-1000” manufactured by Ikeda Rika Co., Ltd.) to obtain hydrophobic silica 1 as a dry powder. .
As a result of measuring the average particle size of the obtained hydrophobic silica 1, the average particle size was 100 nm, and the particles were very uniform in particle size.

[Production Example 9] Preparation of hydrophobic inorganic oxide (hydrophobic silica) Hydrophobic silica 2 was prepared in the same manner as in Production Example 8 except that the internal temperature 40 ° C for preparing the reaction vessel liquid was changed to 43 ° C. Got. The average particle diameter of the hydrophobic silica 2 was 100 nm.

[Example 1]
(Preparation of toner additive)
5 g of the resin particles (1) obtained in Production Example 1 were precisely weighed and 0.05 g of hydrophobic silica (trade name “Aerosil RY200”, manufactured by Nippon Aerosil Co., Ltd.) as a hydrophobic inorganic oxide was weighed accurately. The resin particles and the hydrophobic silica were mixed for 120 seconds with a mixer (trade name “Labo Milser LM-PLUS”, manufactured by Iwatani Corporation) to obtain toner additive (1).
Table 3 shows the average particle diameter and the degree of hydrophobicity of the used hydrophobic silica.
The hydrophobicity of the resin particles (1) used was 19.3%, and the hydrophobicity of the resin particles in the obtained toner additive (1) was 24.2%. Since the hydrophobicity of the resin particles is increased by adding hydrophobic silica, it can be seen that at least a part of the used hydrophobic silica is adhered to the resin particles.
(Preparation of toner for developing electrostatic image)
10 g of negatively chargeable toner particles (trade name “EPT-942T” manufactured by Tokyo Ink; charge amount: −25.5 μC / g) are precisely weighed, and 0.01 g of the toner additive (1) is precisely weighed. The negatively chargeable toner particles and the toner additive (1) are mixed for 90 seconds with a mixer (trade name “Labo Milser LM-PLUS” manufactured by Iwatani Corporation) to obtain a toner for developing an electrostatic image. It was.
Table 4 shows the charge amount of the obtained toner for developing an electrostatic image.

[Examples 2 to 6]
The resin particles shown in Table 3 were used in place of the resin particles (1), and hydrophobic inorganic oxides shown in Table 3 instead of 0.05 g of hydrophobic silica (product name “Aerosil RY200” manufactured by Nippon Aerosil Co., Ltd.) (Japan) For toner in the same manner as in Example 1 except that hydrophobic silica, hydrophobic alumina or hydrophobic titania manufactured by Aerosil Co., Ltd. and hydrophobic silica 1) obtained in Production Example 8 were used in the weights shown in Table 3. Additives (2) to (6) were obtained. Table 3 shows the average particle diameter and the degree of hydrophobicity of the used hydrophobic inorganic oxide.
An electrostatic charge image developing toner was obtained in the same manner as in Example 1 except that the obtained toner additives (2) to (6) were used in the weights shown in Table 4. Table 4 shows the charge amount of the obtained toner for developing an electrostatic image.

[Comparative Example 1]
An electrostatic charge image was obtained in the same manner as in Example 1 except that the resin particles (1) obtained in Production Example 1 were used as they were, that is, the toner additive (C1) containing no hydrophobic inorganic oxide was used. A developing toner was obtained. Table 4 shows the charge amount of the obtained toner for developing an electrostatic image.

[Comparative Examples 2 to 8]
Resin particles shown in Table 3 were used instead of resin particles (1), and inorganic oxides shown in Table 3 (Nippon Aerosil Co., Ltd.) instead of 0.05 g of hydrophobic silica (Nippon Aerosil Co., Ltd., trade name “Aerosil RY200”) Toner additives (C2) to (C2) in the same manner as in Example 1 except that the manufactured hydrophobic silica or hydrophilic silica and the hydrophobic silica 2) obtained in Production Example 9 were used in the weights shown in Table 3. (C8) was obtained. Table 3 shows the average particle size and the degree of hydrophobicity of the inorganic oxide used. In Comparative Example 8, acrylic resin particles (manufactured by Soken Chemical Co., Ltd., trade name “Chemisnow MP-2701”, average particle diameter: 400 nm) were used as the resin particles.
An electrostatic charge image developing toner was obtained in the same manner as in Example 1 except that the obtained toner additives (C2) to (C8) were used in the weights shown in Table 4. Table 4 shows the charge amount of the obtained toner for developing an electrostatic image.

[Reference Example 1]
Instead of negatively chargeable toner particles (trade name “EPT-942T” manufactured by Tokyo Ink; charge amount: −25.5 μC / g), positively chargeable toner particles (charge amount: +23.10 μC / g) were used. Except for the above, an electrostatic image developing toner was obtained in the same manner as in Example 1. Table 4 shows the charge amount of the obtained toner for developing an electrostatic image.
Positively chargeable toner particles were produced as follows.
100 parts of styrene-acrylic acid ester copolymer resin (trade name “SE-0050” manufactured by Sekisui Chemical Co., Ltd.), 3 parts of wax (trade name “FT-100” manufactured by Shell MDS Co., Ltd.), and chromium containing 1 part of a metal dye (made by Orient Chemical Industries, trade name “Bontron S-34”) and 5 parts of carbon black (trade name “MA-100” made by Mitsubishi Chemical Corporation) are mixed for 5 minutes with a super mixer. After hot melt kneading with a pressure kneader, the mixture was pulverized with a jet mill and then classified with a dry air classifier to obtain positively chargeable toner particles having a volume average particle diameter of 10 μm measured with a Coulter counter.

  As apparent from Table 4, the toner additive of the present invention can improve the chargeability of the toner having negative chargeability. Among them, the additive for toner containing resin particles having an average particle diameter of 200 nm or less has a particularly high effect of improving the chargeability.

  On the other hand, a toner additive containing no hydrophobic inorganic oxide (Comparative Example 1), a toner additive using a hydrophilic inorganic oxide instead of the hydrophobic inorganic oxide (Comparative Example 2), and a degree of hydrophobicity Additive for toner using small hydrophobic inorganic oxide (Comparative Example 3), Additive for toner using resin particles having a large average particle size (800 nm) (Comparative Example 4), Content ratio of hydrophobic inorganic oxide Toner additive (Comparative Examples 5 and 7) with a large or small amount, toner additive using a hydrophobic inorganic oxide having a large average particle diameter (Comparative Example 6), and the surface of the resin particles formed of an amino resin Any toner additive (Comparative Example 8) that was not worked worked to lower the chargeability of the toner having negative chargeability.

  Further, as is clear from Reference Example 1, the additive for toner of the present invention can exhibit an effect of improving the chargeability even for toner particles having a positive chargeability.

Claims (5)

At least the surface layer includes resin particles formed from an amino resin, and a hydrophobic inorganic oxide,
The content ratio of the hydrophobic inorganic oxide is 0.05 to 10 parts by weight with respect to 100 parts by weight of the resin particles,
The average particle diameter of the resin particles is 780 nm or less,
The hydrophobic inorganic oxide has an average particle size of 80 nm or less,
The hydrophobicity of the hydrophobic inorganic oxide is 45% or more.
Toner additive.   The toner additive according to claim 1, wherein the hydrophobic inorganic oxide is hydrophobic silica, hydrophobic titania, hydrophobic alumina, hydrophobic zirconia, hydrophobic zinc oxide, hydrophobic tin oxide, or hydrophobic tantalum oxide. Agent. The resin particles have a core-shell structure having a core layer and a shell layer;
The shell layer is formed from an amino resin.
The toner additive according to claim 1 or 2.   An electrostatic charge image developing toner comprising the toner additive according to claim 1. Further comprising toner particles,
The electrostatic charge image developing toner according to claim 4, wherein a content ratio of the toner additive is 0.05 to 1 part by weight with respect to 100 parts by weight of the toner particles.