JP5405050B2 - Method for producing resin particles for toner - Google Patents

Description

The present invention relates to a method for producing toner resin particles. More specifically, the present invention relates to a method for producing resin particles for toner whose surface is coated with a metal oxide layer.

As a method for producing resin particles having a uniform particle size and excellent electrical properties, thermal properties, chemical stability, etc., a method of producing resin particles using polymer fine particles as a dispersion stabilizer is known. (For example, refer to Patent Document 1).
JP 2002-284881 A

However, in this method using polymer fine particles, polymer fine powder adheres to the surface of the resin particles, and therefore, if the low temperature fixability is to be improved, the storage stability may be insufficient. was there.
That is, an object of the present invention is to provide a method for producing resin particles for a toner excellent in both storage stability and low-temperature fixability.

As a result of intensive studies, the present inventors have completed the present invention.
A resin particle for toner, wherein a layer (B) of a metal oxide (c) is formed on the surface of a resin particle (A) having at least one of a hydroxyl group and a carboxyl group on the surface by a sol-gel method. Production method.

According to the resin particles for toner of the present invention, both storage stability and low-temperature fixability can be achieved.

The resin particles for toner produced by the production method of the present invention have at least one of a hydroxyl group and a carboxyl group on the surface of the resin particle (A), and the surface is a part of the metal oxide (c) layer (B). Resin particles for toner, wherein the layer (B) of the metal oxide (c) is coated and has a thickness of 0.1 to 50 nm.

The resin (a) constituting the resin particles (A) is not particularly limited and may be a thermoplastic resin or a thermosetting resin. For example, a vinyl resin, a urethane resin, an epoxy resin, an ester resin Amide resin, imide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, carbonate resin and the like. As the resin (a), two or more of the above resins may be used in combination. Among these, a vinyl resin, a urethane resin, an epoxy resin, an ester resin, and a combination thereof are preferable from the viewpoint of easy particle production. Particularly preferred are vinyl resins, ester resins and combinations thereof.

Among resins (a), particularly preferred resins, that is, ester resins and vinyl resins will be described, but other resins can be used in the same manner.
As the ester resin, a polycondensate of a polyol and a polycarboxylic acid, its acid anhydride, or a lower alkyl (carbon group having 1 to 4 carbon atoms) ester can be used.
A known polycondensation catalyst or the like can be used for the polycondensation reaction.
As the polyol, a known polyol (for example, described in JP-A-2006-206897) can be used, and examples thereof include AO adducts of alkylene glycol and bisphenols. Among these, from the viewpoint of resin strength and melt viscosity, an AO adduct of bisphenols and a mixture thereof with an alkylene glycol are preferred.

The ratio of the polyol and the polycarboxylic acid is preferably 2/1 to 1/1, more preferably 1.5 / 1 to 1 as an equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. 1/1, particularly preferably 1.3 / 1 to 1.02 / 1.

The vinyl resin is a polymer obtained by homopolymerizing or copolymerizing vinyl monomers. A known polymerization catalyst or the like can be used for the polymerization.
As the vinyl monomer, known monomers (for example, described in JP-A-2006-206897) can be used, and examples thereof include styrene and methyl methacrylate.

Although it does not restrict | limit especially as glass transition temperature (henceforth Tg) of resin (a), From a fixed viewpoint, 20-80 degreeC is preferable, More preferably, it is 25-70 degreeC, Most preferably, it is 30. ~ 65 ° C.

The volume average particle diameter of the resin particles (A) is preferably 1 to 10 μm, more preferably 2 to 8 μm, and further preferably 3 to 6 μm. When it is 1 μm or more, the handling property as a powder is improved. If it is 10 μm or less, the resolution of the image is improved.
The ratio DV / DN of the volume average particle diameter DV of the resin particles (A) and the number average particle diameter DN of the resin particles (A) is preferably 1.0 to 1.5, more preferably 1.0 to 1.4. More preferably, it is 1.0 to 1.3. When it is 1.5 or less, powder characteristics (fluidity, charging uniformity, etc.) and image resolution are remarkably improved.

At least one of a hydroxyl group and a carboxyl group exists on the surface of the resin particle (A).
Examples of the production method for obtaining the resin particles (A) having at least one of a hydroxyl group and a carboxyl group on the surface include the following methods.
(1) A method for producing resin particles (A) using a resin (a) having at least one of a hydroxyl group and a carboxyl group.
The method for producing the resin (a) having at least one of a hydroxyl group and a carboxyl group is not particularly limited. For example, in the case of an ester resin, a polyol and a polycarboxylic acid, its acid anhydride or a lower alkyl (carbon number of the alkyl group) 1-4) A polycondensate with an ester can be produced by a polycondensation reaction or the like. In the case of vinyl resin, it is produced by radical polymerization reaction of a monomer having a hydroxyl group (hydroxyethyl acrylate, hydroxyethyl methacrylate, etc.) or a monomer having a carboxyl group (acrylic acid, methacrylic acid, etc.). Can do.

Examples of the method for producing the resin particles (A) include a method in which the resin (a) is made into particles by a pulverization method or a wet dispersion method.
Moreover, the method of superposing | polymerizing the monomer which has at least one of a hydroxyl group and a carboxyl group by an emulsion polymerization method etc., and obtaining the resin particle (A) is mentioned.

(2) A method of introducing at least one of a hydroxyl group and a carboxyl group into the surface of the resin particle (A) after producing the resin particle (A).
A method of producing the resin particles (A) by a known method and introducing a hydroxyl group or a carboxyl group on the resin surface by plasma treatment or the like can be mentioned.

(3) A method of coating the surface of the resin particles (A) with organic fine particles (E) having at least one of a hydroxyl group and a carboxyl group.
Examples of the organic fine particles (E) include resin fine particles and low molecular organic compounds having a melting point of 50 to 120 ° C.
Examples of the resin fine particles include resin particles having the composition mentioned as the resin (a) and produced by the methods (1) and (2).
The volume average particle diameter of the organic fine particles (E) is smaller than the particle diameter of the resin particles (A). The value of particle size ratio [volume average particle size of organic fine particles (E) / [volume average particle size of resin particles (A)] is preferably 0.001 to 0.3, more preferably 0.002 to 0.2. More preferably, it is 0.003 to 0.1, and particularly preferably 0.01 to 0.08.

  The volume average particle diameter of the organic fine particles (E) is preferably 0.01 to 0.5 μm, particularly preferably 0.015 to 0.4 μm. The volume average particle size is determined by a dynamic light scattering particle size distribution measuring device (for example, LB-550: manufactured by Horiba Seisakusho), a laser type particle size distribution measuring device (for example, LA-920: manufactured by Horiba Seisakusho), Multitizer III (Beckman).・ Measured by Coulter, Inc.

The organic fine particles (E) are preferably resin fine particles from the viewpoint of easy production of fine particles, and more preferably acrylic resins.
As a production method for obtaining the resin particles (A) having at least one of a hydroxyl group and a carboxyl group on the surface, the method (3) is preferable from the viewpoint of ease of production.

The metal oxide (c) is not particularly limited as long as it can coat the particle surface, but from the viewpoint of ease of production, silicon oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium oxide, zirconia oxide, oxidation Examples include antimony and natural products containing the metal oxide. Specific examples of natural products include talc, kaolin clay, montmorillonite, mica, bentonite, rholite clay, and chrysotile.
Among these, from the viewpoint of ease of production, at least one selected from the group consisting of silicon oxide, aluminum oxide, magnesium oxide, zinc oxide, and titanium oxide is preferable. Furthermore, silicon oxide and aluminum oxide are preferable.

The film thickness t of the layer (B) of the metal oxide (c) is 0.1 to 50 nm, preferably 0.5 to 40 nm, and more preferably 1 to 30 nm. If t is less than 0.1 nm, the heat-resistant storage stability deteriorates, and if t exceeds 50 nm, the low-temperature fixing temperature becomes high.

As a method for measuring the film thickness t, there is a method in which sample resin particles are hardened with a commercially available epoxy resin, cut with a microcutter, the cross section is observed with a transmission electron microscope (TEM), and the average film thickness is calculated. It is done.

In the resin particles for toner of the present invention, the ratio of the area partially covered with the metal oxide (c) to the surface area of the resin particles (A) (hereinafter referred to as the coverage (u)). From the viewpoint of achieving both storage stability and low-temperature fixability, it is preferably 20 to 80%, more preferably 30 to 75%, and particularly preferably 35 to 70%.
The coverage (u) can be measured by observing the resin particles (A) with an electron microscope (SEM).

As a method of partially covering the surface of the resin particles (A) with the metal oxide (c), a sol-gel method can be mentioned. The sol-gel method is preferable from the viewpoint of manufacturing cost.

As a method for producing the resin particles for toner of the present invention by the sol-gel method, the resin particles are obtained by bringing the metal alkoxide (d) into contact with the surface of the resin particles (A) in a solvent (S) containing no active hydrogen. Examples thereof include a method of forming a metal oxide (c) layer (B) on the surface of (A).
Examples of the solvent (S) not containing active hydrogen include saturated hydrocarbons, ketones, esters, etc., and saturated hydrocarbons having 5 to 20 carbon atoms are preferable from the viewpoint of ease of handling, and decane, octane, and heptane are more preferable. preferable.

Examples of the metal alkoxide (d) include alkoxides such as lithium, sodium, potassium, magnesium, calcium, titanium, zirconium, iron, copper, aluminum, and silicon, and silicon and aluminum alkoxides are preferable from the viewpoint of availability. . The organic part preferably has 4 or less carbon atoms, and specifically, methoxy, ethoxy, propoxy, isopropoxy, and n-butoxy are preferable. The number of alkoxy groups in one molecule is preferably 3 or 4.

As the reaction conditions of the sol-gel method, for example, particles are dispersed in a solvent (S) and heated (30 to 150 ° C.), and the target metal alkoxide is added to the dispersion solvent (S) to react. Let
If necessary, a catalyst may be added. The addition amount of the catalyst is 0 to 5% by weight based on the weight of the resin particles. Catalysts include metal catalysts [tin (dibutyltin dilaurate, stannous octoate, etc.), lead (lead oleate, naphthenate, lead octate, etc.)], amine catalysts [triethylenediamine, dimethylethanolamine, etc. ], Acid [boron trifluoride, hydrochloric acid, etc.], base [amine, alkaline earth metal hydroxide, etc.], salt [quaternary onium salt, etc.], organometallic catalyst [stannous chloride, tetrabutyl zirconate] Etc.], organic acids [paratoluenesulfonic acid, dodecylbenzenesulfonic acid, etc.] and the like.
Examples of the active hydrogen group include a hydroxyl group and a carboxyl group.
The concentration of the resin particles (A) in the dispersion is preferably 0.01 to 10% by volume with respect to the volume of the dispersion.

The coverage (u) of the surface of the resin particles (A) with the metal oxide (c) is, for example, resin particles
It can control by the quantity of the hydroxyl group and carboxyl group which exist on the surface of (A). This is because the hydroxyl group and carboxyl group can react with the metal alkoxide (d) on the surface of the resin particle (A) to form the metal oxide (c) layer (B).
Examples of a method for controlling the amount of hydroxyl group and carboxyl group present on the surface of the resin particle (A) include the following methods.

In the method (1) for imparting at least one of a hydroxyl group and a carboxyl group to the surface of the resin particle (A), the resin (a) is a monomer (p) containing a hydroxyl group or a carboxyl group and a monomer (q) containing no active hydrogen ), The coverage (u) can be changed by changing the ratio of both monomers.
In the method (3), the surface of the resin particles (A) is coated with a mixture of organic fine particles (E) having at least one of hydroxyl group and carboxyl group on the surface and organic fine particles (F) not containing active hydrogen on the surface. The coverage ratio (u) can be changed by changing the weight ratio between the two.
Eventually, the coverage (u) can be controlled by the amount of hydroxyl groups and carboxyl groups present on the surface of the resin particles (A).

The resin particles for toner of the present invention are resin particles for toner containing the resin particles (A), and are coated with a component other than the resin particles (A), for example, a layer (B) of a metal oxide (c). Resin particles and other additives (pigments, fillers, antistatic agents, colorants, release agents, charge control agents, ultraviolet absorbers, antioxidants, antiblocking agents, heat stabilizers, flame retardants, etc. ) Can be mixed. Content of components other than resin particle (A) becomes like this. Preferably it is 0 to 50 weight%, More preferably, it is 2 to 30 weight%.

The electrophotographic toner used in the electrophotographic process is temporarily attached to an image carrier such as a photosensitive member on which an electrostatic charge image is formed in the developing process, and then transferred from the photosensitive member to the transfer paper in the transferring step. After being transferred to a transfer medium such as, it is fixed on the paper surface in a fixing step.
The electrophotographic toner is used by mixing resin particles for toner and inorganic powders such as various metal oxides in order to impart flow characteristics. This inorganic powder is called an external additive.
The electrophotographic toner of the present invention is obtained by adding an external additive to the resin particles of the present invention.

As external additives, for example, silicon dioxide (silica), titanium dioxide (titania), aluminum oxide, zinc oxide, magnesium oxide, cerium oxide, iron oxide, copper oxide, tin oxide and the like are known. In particular, silica particles obtained by reacting silica or titanium oxide fine particles with an organosilicon compound such as dimethyldichlorosilane, hexamethyldisilazane, or silicone oil and replacing the silanol groups on the surface of the silica fine particles with organic groups are preferably used. .
The amount of external additive used (% by weight) is not particularly limited, but is preferably 0.01 to 5 based on the weight of the resin particles for electrophotographic toner, from the viewpoint of compatibility between fixability and fluidity. Preferably, it is 0.1 to 4, particularly preferably 0.5 to 3.
The electrophotographic toner can be produced by adding an external additive to the resin particles for electrophotographic toner and mixing them.

EXAMPLES Next, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples without departing from the gist of the present invention. Unless otherwise specified, “part” means “part by weight” and “%” means “% by weight”. Mn represents a number average molecular weight, and Mw represents a weight average molecular weight.

<Measurement method of coverage (u)>
The resin particles for toner of the present invention were observed with an electron microscope (SEM), 10 coated areas were measured, the average value was calculated, and the coverage (u) was determined. In SEM observation, it is impossible to see the entire surface of one resin particle, but by measuring the coverage area of 10 particles with SEM observation, it was considered that the average coverage area could be measured. .
Further, the coverage of the resin particles (A) coated with fine particles was also measured in the same manner as described above.

<Measurement of film thickness (t) of metal oxide (c) layer (B)>
The resin particles (sample) for toner of the present invention are hardened with a commercially available epoxy resin, cut with a microcutter, the cross section is observed with a transmission electron microscope (TEM), 10 points are collected per layer, and the average value is calculated. . Furthermore, the average of the three or more layers was defined as the film thickness (t).

<Measurement of glass transition temperature>
As a measuring device, DSC20 manufactured by Seiko Denshi Kogyo Co., Ltd. was used, and measurement was performed based on JIS K7121-1987. Specifically, using 5.0 mg of sample, the sample was cooled from 30 ° C. to −20 ° C. at a cooling rate of 90 ° C./min and kept for 10 minutes, and then heated to 120 ° C. at a heating rate of 20 ° C./min, 120 ° C. 10 minutes, then cooled to −20 ° C. at a cooling rate of 90 ° C./min and held for 13 minutes, then heated to 120 ° C. at a heating rate of 20 ° C./min, measured at the time of this second temperature increase. The glass transition temperature was determined using a DSC curve.

<Production Example 1>
A reaction vessel equipped with a stirrer and a dehydrator is charged with 218 parts of bisphenol A / EO 2 mol adduct, 537 parts of bisphenol A / PO 3 mol adduct, 213 parts of terephthalic acid, 47 parts of adipic acid, and 2 parts of dibutyltin oxide. The dehydration reaction was performed at normal pressure and 230 ° C. for 5 hours, and then the dehydration reaction was performed under a reduced pressure of 0.5 kPa for 5 hours. The mixture was further cooled to 180 ° C., 43 parts of trimellitic anhydride was added, and the reaction was performed at normal pressure for 2 hours to obtain [Polyester Resin 1]. [Polyester resin 1] had a Tg of 44 ° C., Mn of 2700, Mw of 6500, and an acid value of 25.

<Production Example 2>
In a reaction vessel equipped with a stirrer and a dehydrator, 681 parts of bisphenol A / EO 2 mol adduct, 81 parts of bisphenol A / PO 2 mol adduct, 275 parts of terephthalic acid, 7 parts of adipic acid, 22 parts of trimellitic anhydride, dibutyl 2 parts of tin oxide was added, and after 5 hours of dehydration reaction at normal pressure and 230 ° C., the dehydration reaction was performed under reduced pressure of 0.5 kPa for 5 hours to obtain [Polyester Resin 2]. [Polyester resin 2] had a Tg of 54 ° C., Mn of 2200, Mw of 9500, an acid value of 0.8, and a hydroxyl value of 53.

<Production Example 3>
407 parts of [Polyester resin 2] obtained in Production Example 2, 54 parts of IPDI, and 485 parts of ethyl acetate were put into an autoclave, and reacted at 100 ° C. for 5 hours in a sealed state. A prepolymer solution 1] was obtained. [Nurethane Prepolymer Solution 1] had an NCO content of 0.8%.

<Production Example 4>
A reaction vessel equipped with a stirrer, a solvent removal apparatus, and a thermometer was charged with 50 parts of isophoronediamine and 300 parts of methyl ethyl ketone, reacted at 50 ° C. for 5 hours, and then desolvated to form a ketimine compound [curing Agent 1] was obtained. The total amine value of [Curing Agent 1] was 415.

<Production Example 5>
In a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, 701 parts of propylene glycol, 716 parts of dimethyl terephthalate, 180 parts of adipic acid, and 3 parts of titanium terephthalate as a condensation catalyst were added at 180 ° C. The reaction was carried out for 8 hours while distilling off the methanol produced under an air stream. Next, while gradually raising the temperature to 230 ° C., the reaction is performed for 4 hours while distilling off the propylene glycol and water produced under a nitrogen stream, and the reaction is further performed under a reduced pressure of 0.5 kPa, and the softening point becomes 150 ° C. It was taken out at the time. The recovered propylene glycol was 316 parts. The resin taken out was cooled to room temperature and then pulverized into particles to obtain polyester resin 3. The polyester resin 3 was Mn8000, Mw23000, Tg70 degreeC.

<Production Example 6>
452 parts of xylene was placed in an autoclave reaction vessel equipped with a thermometer, a stirrer, and a nitrogen introduction tube, and after substitution with nitrogen, a mixed monomer of 845 parts of styrene and 155 parts of n-butyl acrylate at 170 ° C., and di- A mixture of 6.4 parts of t-butyl peroxide and 125 parts of xylene was added dropwise over 3 hours. After dropping, the mixture was aged at 170 ° C. for 1 hour to complete the polymerization. Thereafter, the solvent was removed under reduced pressure to obtain a vinyl resin. The vinyl resin was Mn5000, Mw14000, Tg60 ° C.

<Production Example 7>
In a reaction vessel equipped with a stir bar and a thermometer, water 683 parts, methacrylic acid EO adduct sulfate sodium salt (Eleminol RS-30, manufactured by Sanyo Chemical Industries), 139 parts styrene, 138 parts methacrylic acid, acrylic When 184 parts of butyl acid, 20 parts of hydroxyethyl methacrylate and 1 part of ammonium persulfate were added and stirred at 400 rpm for 15 minutes, a white emulsion was obtained. The system was heated to raise the system temperature to 75 ° C. and reacted for 5 hours. Further, 30 parts of a 1% ammonium persulfate aqueous solution was added, and the mixture was aged at 75 ° C. for 5 hours, followed by vinyl resin (styrene-methacrylic acid-butyl methacrylate-hydroxyethyl methacrylate-methacrylic acid EO adduct sulfate sodium salt An aqueous dispersion [fine particle dispersion] was obtained. The volume average particle diameter of the [fine particle dispersion 1] measured by LA-920 was 0.15 μm.

<Production Example 8>
In a reaction vessel equipped with a stirrer and a thermometer, 683 parts of water, 11 parts of a sodium salt of methacrylic acid EO adduct sulfate (Eleminol RS-30, manufactured by Sanyo Chemical Industries), 139 parts of styrene, 138 parts of methyl methacrylate, When 184 parts of butyl acrylate and 1 part of ammonium persulfate were added and stirred at 400 rpm for 15 minutes, a white emulsion was obtained. The system was heated to raise the system temperature to 75 ° C. and reacted for 5 hours. Further, 30 parts of a 1% ammonium persulfate aqueous solution was added, and the mixture was aged at 75 ° C. for 5 hours to obtain an aqueous vinyl resin (a copolymer of styrene-methyl methacrylate-butyl methacrylate-methacrylic acid EO adduct sulfate sodium salt). A dispersion [fine particle dispersion] was obtained. The volume average particle diameter of the [fine particle dispersion 2] measured by LA-920 was 0.15 μm.

<Production Example 9>
955 parts of water, 10 parts of [Fine Particle Dispersion 1], 5 parts of [Fine Particle Dispersion 2], 30 parts of an aqueous solution of sodium dodecyl diphenyl ether disulfonate (Eleminol MON7, manufactured by Sanyo Chemical Industries) are placed in a container equipped with a stir bar. A milky white liquid [aqueous phase 1] was obtained.

<Production Example 10>
In a container in which a stir bar is set, 15 parts of [fine particle dispersion 1], 955 parts of water, and 30 parts of sodium dodecyl diphenyl ether disulfonate aqueous solution (Eleminol MON7, manufactured by Sanyo Chemical Industries) are put into a milky white liquid [aqueous phase 2]. Got.

<Production Example 11>
955 parts of water, 5 parts of [fine particle dispersion 1], 10 parts of [fine particle dispersion 2], and 30 parts of sodium dodecyl diphenyl ether disulfonate aqueous solution (Eleminol MON7, manufactured by Sanyo Chemical Industries) are placed in a container equipped with a stir bar. A milky white liquid [aqueous phase 3] was obtained.

<Production Example 12>
In a container in which a stir bar is set, 955 parts of water, 50 parts of a silica dispersion (catalyst S-20L, average particle diameter 17 nm, SiO ₂ 10% by weight), sodium dodecyl diphenyl ether disulfonate aqueous solution ( 30 parts of ELEMINOL MON7 (manufactured by Sanyo Chemical Industries) were added to obtain a milky white liquid [aqueous phase 4].

<Production Example 13>
955 parts of water and 100 parts of a sodium dodecyl diphenyl ether disulfonate aqueous solution (Eleminol MON7, manufactured by Sanyo Kasei Kogyo Co., Ltd.) were added to a container equipped with a stir bar to obtain a transparent liquid [Aqueous Phase 5].

<Production Example 14>
Into a beaker, 177 parts of [Polyester resin 1], 181 parts of ethyl acetate, 39.2 parts of [Urethane prepolymer solution 1], 0.9 part of [Curing agent 1], and 2.8 parts of triethylamine were dissolved and dissolved. The mixture was homogenized to obtain [Resin Solution 1]. 600 parts of [Aqueous phase 1] is added to this [Resin solution 1], a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) is used, a dispersion operation is performed at 25 ° C. for 1 minute at a rotational speed of 12000 rpm, and a film The pressure was reduced to 10 Pa with an evaporator, and the solvent was removed for 30 minutes under the conditions of a temperature of 40 ° C. and a rotation speed of 100 rpm to obtain an aqueous resin dispersion (D1).
(D1) Centrifugating 100 parts, adding 60 parts of water, centrifuging and solid-liquid separation was repeated twice, followed by drying at 35 ° C. for 1 hour and classification to obtain volume average particles. Resin particles (A-1) having a diameter of 6.0 μm and a coverage of fine particles on the surface of 100% were obtained.

<Production Example 15>
In Production Example 14, 1,600 parts of the aqueous phase was changed to 2,600 parts of the aqueous phase, 1,39.2 parts of the urethane prepolymer solution were changed to 3,24 parts of the polyester resin, and the curing agent 1 and triethylamine were not used. Otherwise in the same manner as in Production Example 14, resin particles (A-2) having a volume average particle diameter of 6.0 μm and a surface fine particle coverage of 100% were obtained.

<Production Example 16>
The water phase 1,600 parts of Production Example 14 was changed to 3,600 parts of water phase, the polyester resin 1,177 parts were changed to 177 parts of the vinyl resin of Production Example 6, the urethane prepolymer solution 1, the curing agent 1 and Resin particles (A-3) having a volume average particle diameter of 6.0 μm and a surface fine particle coverage of 100% were obtained in the same manner as in Production Example 14 except that triethylamine was not used.

<Production Example 17>
Resin particles having a volume average particle diameter of 6.0 μm and a coverage of fine particles on the surface of 100% in the same manner as in Production Example 14 except that 1,600 parts of aqueous phase in Production Example 14 are changed to 4,600 parts of water phase. (A-4) was obtained.

<Production Example 18>
Resin particles having a volume average particle diameter of 6.0 μm and a coverage of fine particles on the surface of 0% in the same manner as in Production Example 14, except that 1,600 parts of aqueous phase in Production Example 14 are changed to 5,600 parts of water phase. (A-5) was obtained.

<Example 1>
50 parts of resin particles (A-1) were placed in a reaction vessel equipped with a thermometer and a stirring rod, and the vessel was heated to 30 ° C. (hereinafter, kept at 30 ° C. until cooled). 500 parts of decane and 10 parts of tetramethoxysilane were added and allowed to react for 10 hours. After the reaction, the mixture was cooled and filtered to remove the particles, whereby the resin particles for toner (P-1) of the present invention were obtained.

<Example 2>
Resin particles for toner (P-2) of the present invention were obtained in the same manner as in Example 1 except that the resin particles (A-1) were changed to (A-2).

<Example 3>
Resin particles for toner (P-3) of the present invention were obtained in the same manner as in Example 1 except that the resin particles (A-1) were changed to (A-3).

<Example 4>
Resin particles for toner (P-4) were obtained in the same manner as in Example 1 except that 10 parts of tetramethoxysilane was changed to 10 parts of triethoxyaluminum.

<Comparative Example 1>
Resin particles for toner (P-5) were obtained in the same manner as in Example 1 except that the resin particles (A-1) were changed to resin particles (A-4).

<Comparative example 2>
The resin particles (A-5) were directly used as toner resin particles (P-6).

<Heat resistant storage stability>
10g of sample (resin particles for toner) is stored at 30% humidity, no load for 8 hours at 50 ° C, then screened with a 42-mesh sieve for 2 minutes using a vibrating sieve, and heat-resistant with residual rate on the wire mesh It was used as an index of sex. The heat resistant storage stability was evaluated in the following four stages. (×: 30% or more, Δ: 10-30%, ○: less than 10%)

<Low temperature fixability>
After adding 1.0% Aerosil R972 (manufactured by Nippon Aerosil Co., Ltd.) to the silica-coated resin particles and mixing well to make it uniform, this powder is uniformly placed on the paper surface so as to be 0.6 mg / cm ² (this When the powder is placed on the paper, a printer from which the heat fixing machine is removed is used (other methods may be used as long as the powder can be uniformly placed at the above-mentioned weight density). The temperature at which cold offset was generated when passing through a pressure roller under conditions of a fixing speed (heating roller peripheral speed) of 213 mm / sec and a fixing pressure (pressure roller pressure) of 10 kg / cm ² was measured.

Table 1 shows the evaluation results and the physical property values of the resin particles obtained by the production method of the present invention.

In Examples 1 to 4, heat-resistant storage stability and low-temperature fixability were good, whereas in Comparative Example 1, the low-temperature fixability was remarkably deteriorated. Moreover, the comparative example 2 was inferior in heat resistant storage stability.

The resin particles obtained by the production method of the present invention are extremely useful for electrophotographic toners. In addition, paint additives, cosmetic additives, paper coating additives, slush molding resins, powder coatings, electronic component manufacturing spacers, electronic measuring instrument standard particles, electronic paper particles, medical diagnostic carriers It is also useful as electrorheological particles and other molding resin particles.

Claims (4)

After producing the resin particles for toner by forming the metal oxide (c) layer (B) on the surface of the resin particles (A) having at least one of a hydroxyl group and a carboxyl group on the surface by the sol-gel method , A method for producing an electrophotographic toner, wherein an external additive is added to and mixed with resin particles for toner, wherein the thickness (t) of the layer (B) of the metal oxide (c) is 1 to 1. An electrophotographic toner having a coverage (u) of 20 to 80% with a metal oxide (c) of resin particles (A) of 30 nm Manufacturing method. The layer (B) of the metal oxide (c) is formed by bringing the metal alkoxide (d) into contact with the surface of the resin particles (A) in a solvent (S) not containing active hydrogen. Toner for electrophotography Manufacturing method. The toner for electrophotography according to claim 2, wherein the solvent (S) is a saturated hydrocarbon having 5 to 20 carbon atoms. Manufacturing method. 4. The toner for electrophotography according to claim 2, wherein the metal alkoxide (d) is an alkoxide of silicon or aluminum. Manufacturing method.