JP2009098528A - Method for producing toner for electrostatic charge image development - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method which can easily produce a toner for electrostatic charge image development, even if a crystalline resin is used, having excellent low temperature fixability and storage stability and further having excellent durability in a short time, to provide toner for electrostatic charge image development obtained by the method, and to provide an image forming method using the toner. <P>SOLUTION: A method for producing a toner for electrostatic charge image development at least includes: a stage where the raw material of a toner base particle including a binding resin containing a crystalline resin in which the ratio between a softening point and the maximum peak temperature in heat absorption (the softening point/the maximum peak temperature in heat absorption) is 0.6 to 1.3, and a coloring agent is melted and kneaded, so as to obtain a melted and kneaded material; a stage where the obtained melted and kneaded material is pulverized, so as to obtain a pulverized material; a classifying stage where the obtained pulverized material is classified, so as to obtain a toner base particle; and an external addition stage where the obtained toner base particle and an external additive are mixed, so as to obtain an externally added toner, and further includes a stage where the treated material on and after the melt-kneading stage is irradiated with microwaves. The toner for electrostatic charge image development is obtained by the production method, and used for an image forming apparatus, in which linear velocity is ≥750 mm/sec, in the image forming method using. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrostatic charge image developing toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, a manufacturing method thereof, and an image forming method using the toner.

  In recent years, in electrophotographic technology, from the viewpoint of increasing printing speed and saving energy, development of a toner having excellent low-temperature fixability that can be fixed with as low energy as possible has become an important issue. As one of the technologies for that purpose, addition of a crystalline resin into a binder resin has been studied (for example, refer to Patent Documents 1 and 2), and a crystalline resin having a sudden viscosity change at the melting point is used. Thus, the toner has a sharp melt property, and an improvement in low-temperature fixability is achieved.

  However, when a crystalline resin is added to an amorphous binder resin, the low-temperature fixability of the toner is improved. However, since the amorphous resin is plasticized, the storage stability and durability of the toner are deteriorated. .

Therefore, in recent years, as a new technology for solving this, the intermediate product in the toner production stage or the final product is subjected to heat treatment, thereby increasing the crystallinity of the crystalline resin in the toner and making the toner thermally A so-called “annealing” technique that stabilizes the temperature is being studied. This achieves both low-temperature fixability and storage stability of the toner (see, for example, Patent Documents 3 and 4).
Japanese Patent No. 2931899 JP 2003-167384 A JP 2006-65015 A JP 2006-65077 A

  However, since the annealing process takes several hours to several tens of hours, the productivity is poor, and a large-scale facility is required, so that a large capital investment is required.

  An object of the present invention is to provide a method for easily and easily producing a toner for developing an electrostatic charge image that is excellent in low-temperature fixability and storage stability and is excellent in durability even when a crystalline resin is used, An object of the present invention is to provide a toner for developing an electrostatic image obtained by the method and an image forming method using the toner.

The present invention
[1] Melting the raw material of toner base particles containing a binder resin and a colorant containing a crystalline resin having a ratio of softening point to maximum endothermic peak temperature (softening point / maximum endothermic peak temperature) of 0.6 to 1.3 A step of kneading to obtain a melt-kneaded product, a step of pulverizing the obtained melt-kneaded product to obtain a pulverized product, a classifying step of classifying the obtained pulverized product to obtain toner base particles, and an obtained toner base A method for producing an electrostatic charge image developing toner comprising at least an external addition step of mixing particles and an external additive to obtain an external addition toner, and further, a step of irradiating a processed product after the melt kneading step with microwaves A method for producing a toner for developing an electrostatic image, comprising:
[1] An electrostatic image developing toner obtained by the production method of [1], and [3] an image forming apparatus having a linear velocity of 750 mm / sec or more, the electrostatic image developing toner of [2]. The present invention relates to an image forming method for use in

  By the method of the present invention, a toner for developing an electrostatic image having excellent low-temperature fixability and storage stability and excellent durability can be easily produced in a short time.

  The present invention includes a step of melt-kneading a toner raw material containing a crystalline resin as a binder resin to obtain a melt-kneaded product, a step of pulverizing the obtained melt-kneaded product to obtain a pulverized product, and classifying the obtained pulverized product Further, when the toner is produced by a method including at least a classification step of obtaining toner base particles, and an external addition step of mixing the obtained toner base particles and an external additive to obtain an external addition toner, further melting It has a great feature in that a process of irradiating microwaves to the processed material after the kneading process is performed. By irradiating with microwaves, the crystalline structure of the crystalline resin broken in the melt-kneading process is recrystallized, and even if crystalline resin is used, it has excellent low-temperature fixability, storage stability and durability. The toner for developing an electrostatic image can be easily produced in a short time. Further, in the present invention, not only the crystalline resin is recrystallized but also the processed product is spheroidized by microwave irradiation. Therefore, the microwave irradiation step is preferably performed after the pulverization step because the surface shape of the toner can be controlled. From the viewpoint of improving the durability of the toner, the microwave is applied to the processed material after the external addition step. Is more preferable.

  In the present invention, the binder resin preferably contains at least a crystalline resin, and further contains an amorphous resin from the viewpoint of storage stability. In the present invention, “crystalline resin” refers to a resin having a crystallinity index of 0.6 to 1.3, preferably 0.8 to 1.2, and “amorphous resin” refers to a crystallinity index of greater than 1.3 or 0.6. A resin that is less than, preferably greater than 1.3 and less than or equal to 4.0. In general, a resin having a crystallinity index exceeding 1.3 is amorphous, and a resin having a crystallinity index of less than 0.6 has low crystallinity and many amorphous portions. Here, the crystallinity index is a physical property that is an index of the degree of crystallization of the resin, and is a ratio of the softening point of the resin to the highest endothermic peak temperature by the differential scanning calorimeter (softening point / highest endothermic peak temperature). ). The degree of crystallization can be adjusted by the type and ratio of the raw material monomers, production conditions (for example, reaction temperature, reaction time, cooling rate) and the like. The highest endothermic peak temperature refers to the temperature of the peak on the highest temperature side among the observed endothermic peaks. If the maximum peak temperature is within 20 ° C. from the softening point, the melting point is set, and the peak having a difference from the softening point exceeding 20 ° C. is a peak due to glass transition.

  The crystalline resin and the amorphous resin are preferably polyesters from the viewpoint of low-temperature fixability of the toner.

  Both the crystalline polyester and the amorphous polyester are obtained by using an alcohol component and a carboxylic acid component as raw material monomers and subjecting them to condensation polymerization.

  The alcohol component in the crystalline polyester preferably contains a monomer that promotes the crystallinity of the resin, such as an aliphatic diol having 2 to 8 carbon atoms.

  Examples of the aliphatic diol having 2 to 8 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, Examples include 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, 1,4-butenediol, and α, ω-linear alkanediol is particularly preferable. These may be contained alone or in admixture of two or more.

  The content of the aliphatic diol having 2 to 8 carbon atoms is preferably 80 mol% or more, more preferably 85 mol% or more, and further preferably 90 mol% or more in the alcohol component from the viewpoint of enhancing crystallinity. Further, when two or more kinds of aliphatic diols having 2 to 8 carbon atoms are used, one kind of the aliphatic diol in them contains 70 mol% or more, preferably 80 to 95 mol% in the alcohol component. It is desirable to occupy. Among these, 1,4-butanediol and 1,6-hexanediol are preferable, and 1,6-hexanediol is more preferable. These are contained in the alcohol component, preferably 70 mol% or more, more preferably 80 mol% or more. It is desirable that

  Examples of the alcohol component in the amorphous polyester include polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane, etc. (I):

(In the formula, RO is an alkyleneoxy group, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers indicating the average number of added moles of alkylene oxide, and the sum of x and y is 1 to 16, preferably 1.5-5)
It is preferable that the monomer which accelerates | stimulates amorphization of resin, such as aromatic diols, such as alkylene oxide adduct of bisphenol A represented by these, is contained.

  The content of the alkylene oxide adduct of bisphenol A represented by the formula (I) is preferably 50 mol% or more, more preferably 70 mol% or more, more preferably 90 mol% or more in the alcohol component from the viewpoint of charge stability. Is more preferable.

  The carboxylic acid compound contained in the carboxylic acid component includes fumaric acid, adipic acid, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, sebacic acid, azelaic acid, n- Aliphatic dicarboxylic acids having 2 to 30 carbon atoms, preferably 2 to 8 carbon atoms such as dodecyl succinic acid and n-dodecenyl succinic acid; Aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid; Dicarboxylic acid: Trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid, anhydrides of these acids, and alkyl (C1-3) esters of acids. Among these, aliphatic dicarboxylic acid compounds are preferable, and in the case of crystalline polyesters, from the viewpoint of increasing the crystallinity, the aliphatic dicarboxylic acid compounds having 2 to 8 carbon atoms are crystalline polyesters in the case of amorphous polyesters. From the viewpoint of dispersibility, fumaric acid is more preferable.

  From the viewpoint of dispersibility of the crystalline polyester, the content of the aliphatic dicarboxylic acid compound is preferably 70 mol% or more, more preferably 80 to 100 mol%, still more preferably 90 to 100 mol% in the carboxylic acid component.

  Note that the molar ratio of the carboxylic acid component to the alcohol component (carboxylic acid component / alcohol component) in the crystalline polyester is preferably higher in the alcohol component than the carboxylic acid component when increasing the molecular weight of the crystalline polyester. Furthermore, since the molecular weight of the polyester can be easily adjusted by distilling off the alcohol component during the reaction under reduced pressure, 0.9 to 1 is preferable, and 0.95 to 1 is more preferable.

  In addition, a monovalent alcohol may be appropriately contained in the alcohol component, and a monovalent carboxylic acid compound may be appropriately contained in the carboxylic acid component from the viewpoint of adjusting the molecular weight.

  The polyester is obtained by polycondensing an alcohol component and a carboxylic acid component, for example, in an inert gas atmosphere, if necessary, in the presence of an esterification catalyst. The reaction temperature is preferably 120 to 230 ° C. in the production of crystalline polyester, and 180 to 250 ° C. in the production of amorphous polyester.

  In the production of crystalline polyester, all monomers are charged together to increase the strength of the resin, or divalent monomers are first reacted in order to reduce low molecular weight components. You may use methods, such as adding a monomer and making it react. Further, the reaction may be accelerated by reducing the pressure of the reaction system in the latter half of the polymerization.

  In order to obtain a higher molecular weight crystalline polyester, the molar ratio of the carboxylic acid component and the alcohol component is adjusted as described above, the reaction temperature is increased, the amount of catalyst is increased, and dehydration is performed for a long time under reduced pressure. What is necessary is just to select reaction conditions, such as performing reaction. In addition, under high power required for stirring, it is possible to produce a high-viscosity crystalline polyester having a high molecular weight. However, when producing without particularly selecting production equipment, the raw material monomer is a non-reactive low-viscosity resin. A method of reacting with a solvent is also an effective means.

  The softening point of the crystalline polyester is preferably from 70 to 140 ° C, more preferably from 80 to 130 ° C, and even more preferably from 105 to 130 ° C, from the viewpoint of low-temperature fixability of the toner.

  The melting point of the crystalline polyester is preferably 60 to 140 ° C., more preferably 70 to 130 ° C., and further preferably 80 to 120 ° C. from the viewpoint of toner fixing properties.

  The softening point of the amorphous polyester is preferably from 80 to 150 ° C, more preferably from 85 to 145 ° C, and even more preferably from 90 to 145 ° C, from the viewpoint of low-temperature fixability and durability of the toner.

  The glass transition point of the amorphous polyester is preferably 40 to 80 ° C., more preferably 50 to 70 ° C., from the viewpoint of the pulverization property of the melt-kneaded product and the storage stability of the toner.

  The acid value of the crystalline polyester and the amorphous polyester is preferably from 0.1 to 30 mgKOH, more preferably from 0.5 to 10 mgKOH, from the viewpoint of environmental stability of the toner, and the hydroxyl value is from the viewpoint of environmental stability of the toner. 1-50 mgKOH / g is preferable, and 10-30 mgKOH / g is more preferable.

  From the viewpoint of dispersibility of the crystalline polyester, the crystalline polyester and the amorphous polyester are preferably those obtained using at least one common compound as a raw material monomer. Such a common compound is preferably a carboxylic acid component, fumaric acid and phthalic acid are more preferable, and fumaric acid is more preferable from the viewpoint of increasing the crystallinity of the crystalline polyester.

  In the present invention, the polyester may be a polyester modified to such an extent that the characteristics are not substantially impaired. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. And a composite resin having two or more kinds of resin units including a polyester unit.

In the production of the crystalline polyester, the raw material monomer may be polymerized in the presence of wax from the viewpoint of improving the grindability of the melt-kneaded product and the productivity of the toner. The wax may be any of hydrocarbon wax, ester wax, amide wax, etc., but hydrocarbon wax is preferred from the viewpoint of compatibility with crystalline polyester and releasability. The hydrocarbon wax generally has a main skeleton represented by — (CH ₂ —CH (R)) n— (wherein R represents a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms), Specific examples include polyethylene waxes such as Fischer-Tropsch wax, polypropylene wax, polyethylene-polypropylene wax, microcrystalline wax, and paraffin wax. Among these, from the viewpoint of improving the grindability of crystalline polyester, polyethylene wax and Polypropylene wax is preferred, and polypropylene wax is more preferred. The melting point of the wax is preferably 70 to 170 ° C, more preferably 100 to 150 ° C. The blending amount of the wax is preferably 1 to 20 parts by weight and more preferably 5 to 15 parts by weight with respect to 100 parts by weight of the raw material monomer of the crystalline polyester.

  The content of the crystalline resin is preferably 2 to 35% by weight and more preferably 3 to 30% by weight in the binder resin from the viewpoint of low temperature fixability and durability of the toner.

  When the binder resin contains an amorphous resin, from the viewpoint of dispersibility of the crystalline polyester, the weight ratio of the crystalline resin to the amorphous resin (crystalline resin / amorphous resin) is 3 / 97-35 / 65 is preferable, and 5 / 95-30 / 70 is more preferable.

  Note that both the crystalline resin and the amorphous resin may be composed of a plurality of resins.

  The binder resin may appropriately contain a resin other than polyester such as vinyl resin, epoxy resin, polycarbonate, polyurethane and the like.

  As the colorant, all of dyes and pigments used as toner colorants can be used, such as carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Isoindoline, Disazo Yellow and the like can be used, and the toner of the present invention may be either black toner or color toner.

  The content of the colorant is preferably 1 to 40 parts by weight and more preferably 2 to 10 parts by weight with respect to 100 parts by weight of the binder resin from the viewpoint of maintaining image density and low-temperature fixability.

  The toner base particles further include a release agent, charge control agent, magnetic powder, fluidity improver, conductivity modifier, extender pigment, reinforcing filler such as fibrous substance, antioxidant, anti-aging agent, cleaning Additives such as property improvers may be contained.

  The toner for developing an electrostatic charge image of the present invention is a step of obtaining a melt-kneaded product by melt-kneading raw materials of toner base particles containing a binder resin and a colorant, and pulverizing the obtained melt-kneaded product to obtain a pulverized product. Obtained through a step, a classification step of classifying the obtained pulverized product to obtain toner base particles, and an external addition step of mixing the obtained toner base particles and an external additive to obtain an external additive, and Then, a process of irradiating microwaves to the processed material after the melt kneading is performed. The processed product after the melt-kneading step means a production intermediate product obtained after the melt-kneading step, a melt-kneaded product obtained by melt-kneading, a pulverized product obtained by the pulverizing step, and a classified product obtained by the classification step. (Toner base particles), externally added toner after the external addition process, processed products in each process, and the like are included.

  Microwave is a general term for electromagnetic waves having a wavelength of about 3 to 30 cm (frequency: 1000 MHz to 10000 MHz). The microwaves used in the present invention include electromagnetic waves having a frequency of 915 MHz or 2450 MHz that can be used for industrial heating (high-frequency induction heating), but 2450 MHz is the most popular frequency for home microwave ovens, In the present invention, a frequency of 2450 MHz is preferable.

  The microwave output is preferably 100 to 1200 W, more preferably 300 to 1000 W, from the viewpoint of production efficiency and safety.

  The microwave irradiation time is preferably 1 to 60 minutes and more preferably 3 to 30 minutes from the viewpoint of production efficiency and safety.

  The temperature of the treatment object to be irradiated with the microwave is preferably (Tg to Tg + 50) ° C., more preferably (Tg to Tg + 40) ° C., more preferably from the viewpoint of efficient crystallization so that the treatment object does not melt. It is desirable to adjust to (Tg-Tg + 30) ° C. Here, Tg is the glass transition point of the treatment object to be irradiated with microwaves, that is, the treatment object before microwave irradiation.

  Hereinafter, each process other than the microwave irradiation process will be described.

  Melt kneading of the raw material of the toner base particles can be performed using a known kneader such as a closed kneader, a single or biaxial extruder, or an open roll type kneader. From the viewpoint, it is preferable to use a twin screw extruder. The temperature of the melt-kneading is not particularly limited as long as the raw materials are sufficiently mixed. In addition, it is preferable to use for the melt-kneading process, after mixing raw materials, such as binder resin and a coloring agent with which it uses for a melt-kneading process, and the release agent used suitably, and a charge control agent, using a Henschel mixer etc.

  The melt-kneaded product obtained by the melt-kneading process is rolled and cooled. The method of rolling and cooling is not particularly limited. Examples of the rolling means include a rolling roll and a rolling drum, and examples of the cooling means include an air cooling method, a water cooling method, and a steel cooling belt method. The thickness after rolling can be adjusted by adjusting the interval between the rolling rolls and the rolling drum.

  The thickness of the melt-kneaded material that is subjected to cooling after rolling is preferably 3 mm or more, more preferably 4 to 6 mm, from the viewpoints of improvement in wax dispersibility and productivity.

  In the pulverization step, from the viewpoint of improving durability, the obtained melt-kneaded product is cooled to such an extent that it can be pulverized, and is preferably pulverized to a volume median particle size of 20 μm or less, more preferably 10 μm or less.

The pulverization process may be performed in multiple stages. For example, the melt-kneaded product is coarsely pulverized so that the volume median particle size (D ₅₀ ) is about 1 to 5 mm, and then the desired particle size, for example, the volume median particle size (D ₅₀ ) is 4 to 12 μm. You may pulverize so that it may become. Moreover, in order to improve the productivity at the time of a grinding | pulverization and a classification process, you may grind | pulverize, after mixing melt-kneaded material with inorganic fine particles, such as hydrophobic silica. In the present specification, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size.

  The pulverizer used in the pulverization step is not particularly limited. For example, examples of the pulverizer suitably used for the coarse pulverization include an atomizer and a rotoplex, but a hammer mill or the like may be used. Further, examples of the pulverizer suitably used for fine pulverization include a jet mill, a collision plate mill, and a rotary mechanical mill.

  When the pulverization process is performed in multiple stages, the pulverized product obtained in the intermediate pulverization process such as the coarse pulverization process, for example, when the pulverization process is composed of a coarse pulverization process and a fine pulverization process, Is also included in the processed product irradiated with microwaves.

  Examples of the classifier used in the classification process include an air classifier, an inertia classifier, and a sieve classifier. In the classification step, the pulverized product which has been removed due to insufficient pulverization may be subjected to the pulverization step again, and may be repeated with the pulverization step and the classification step as necessary.

After the melt-kneading step, an external addition step is performed in which the toner base particles obtained through the pulverization step and the classification step are mixed with an external additive, and the external additive is externally added to the toner surface. The volume median particle size (D ₅₀ ) of the toner base particles is preferably 4 to 12 μm, and more preferably _{5 to} 10 μm.

  Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide. Among these, silica with low specific gravity is used from the viewpoint of preventing embedding of the external additive in the toner. Is preferred.

From the viewpoint of environmental stability of the toner, the silica is preferably hydrophobic silica that has been subjected to a hydrophobic treatment. The method of hydrophobizing is not particularly limited, and examples of the hydrophobizing agent include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, methyltriethoxysilane, and the like. From the viewpoint of environmental stability, hexamethyldisilazane is preferable. The treatment amount of the hydrophobizing agent is preferably 1 to 7 mg / m ² per surface area of the inorganic fine particles.

  As the external additive, silica (silica A) having an average particle diameter of preferably 12 to 120 nm, more preferably 35 to 80 nm, and still more preferably 40 to 60 nm is preferably used. From the viewpoint of imparting fluidity to the toner, It is more preferable to use silica (silica B) having a smaller average particle diameter than silica A together with silica A.

  The external addition amount of silica A is preferably 0.3 parts by weight or more, more preferably 0.3 to 5.0 parts by weight, and more preferably 0.5 to 5.0 parts by weight with respect to 100 parts by weight of the toner base particles from the viewpoint of preventing silica from being embedded in the toner and preventing free silica. More preferred is ~ 2.0 parts by weight.

  The average particle diameter of the silica B is preferably 10 to 30 nm, more preferably 10 to 20 nm, from the viewpoint of imparting fluidity of the toner.

  Further, the ratio of the average particle diameter of silica A and silica B (silica A / silica B) is preferably 1.2 to 10, more preferably 1.5 to 5, and further preferably 2.0 to 3.0, from the viewpoint of imparting appropriate fluidity. .

  The external addition amount of silica B is preferably 0.1 parts by weight or more, more preferably 0.1 to 4.0 parts by weight, more preferably 0.2 to 100 parts by weight with respect to 100 parts by weight of the toner base particles, from the viewpoint of imparting appropriate chargeability and fluidity to the toner. More preferred is ~ 2.0 parts by weight.

  The external addition step is preferably a dry mixing method in which the external additive and the toner base particles are mixed using a high-speed stirrer such as a Henschel mixer or a super mixer, a V-type blender or the like. When a plurality of types of external additives are used, they may be mixed in advance and added to a high-speed stirrer or a V-type blender, or may be added separately.

  After the external addition step, it is preferable to perform a sieving step of removing coarse powder (aggregates) by sieving the toner. When the microwave irradiation step and the sieving step are performed after the external addition step, the microwave irradiation step is preferably performed between the external addition step and the sieving step.

  In the present invention, a toner having high sphericity can be obtained by the microwave irradiation process. The average circularity of the toner obtained by the present invention is preferably from 0.930 to 0.980, more preferably from 0.940 to 0.980, and even more preferably from 0.950 to 0.970, from the viewpoint of improving the durability of the toner. The average circularity of the toner is:

Is the average value of the circularity calculated by the equation, and the “peripheral length of a circle having the same area as the projected image of the particle” and “peripheral length of the projected particle image” are, for example, a flow particle image analyzer (FPIA-1000, FPIA-2000 or FPIA-3000 (manufactured by Sysmex Corporation) is used to measure the toner in an aqueous dispersion. Since the value obtained by the above-mentioned analyzer is a value obtained as an average value of several thousand and at least 3000, the reliability of the average circularity in the present invention is extremely high. In the present specification, the average circularity measuring device is not limited to the above-mentioned device, and any device can be used as long as the average circularity can be obtained based on the above equation based on the same principle. May be measured.

  The softening point of the toner is preferably from 80 to 140 ° C, more preferably from 90 to 130 ° C, from the viewpoints of durability and low-temperature fixability. Further, the glass transition point of the toner is preferably 40 to 80 ° C., more preferably 50 to 70 ° C. from the viewpoint of storage stability and low-temperature fixability.

  The dielectric constant (ε) of the toner is preferably 2.0 to 6.0 and more preferably 3.0 to 5.0 from the viewpoint of avoiding dielectric breakdown in the developing machine. The dielectric constant of the toner can be adjusted by adding carbon black or adding a conductive agent.

  Further, the dielectric loss tangent (tan δ) of the toner is preferably 0.0020 to 0.0200, more preferably 0.0050 to 0.0150 from the viewpoint of avoiding dielectric breakdown in the developing machine. The dielectric loss tangent of the toner can be adjusted by adding carbon black or adding a conductive agent.

  The electrostatic image developing toner of the present invention can be used as it is as a one-component developing toner as it is, but the toner of the present invention is excellent in durability and the effect of the present invention on the suppression of toner spent on the carrier. Therefore, it is preferable to mix with a carrier and use as a two-component developer.

In the present invention, from the viewpoint of image characteristics, it is preferable to use a carrier with low saturation magnetization that weakens the area around the magnetic brush. Saturation magnetization of the carrier is preferably ^{40~100Am 2 / kg, 50~90Am 2 /} kg is more preferable. The saturation magnetization is preferably 100 Am ² / kg or less from the viewpoint of adjusting the hardness of the magnetic brush and maintaining gradation reproducibility, and preferably 40 Am ² / kg or more from the viewpoint of preventing carrier adhesion and toner scattering.

  As the core material of the carrier, those made of known materials can be used without particular limitation, for example, ferromagnetic metals such as iron, cobalt, nickel, magnetite, hematite, ferrite, copper-zinc-magnesium ferrite, Examples include alloys and compounds such as manganese ferrite and magnesium ferrite, and glass beads. Among these, iron powder, magnetite, ferrite, copper-zinc-magnesium ferrite, manganese ferrite, and magnesium ferrite are preferable from the viewpoint of chargeability. From the viewpoint of image quality, ferrite, copper-zinc-magnesium ferrite, manganese ferrite and magnesium ferrite are more preferable.

  The surface of the carrier is preferably coated with a resin from the viewpoint of preventing spent. The resin that coats the carrier surface varies depending on the toner material. For example, fluororesin such as polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin such as polydimethylsiloxane, polyester, styrenic resin, Acrylic resins, polyamides, polyvinyl butyral, amino acrylate resins, and the like can be used, and these can be used alone or in combination of two or more. However, when the toner is negatively charged, the chargeability and surface From the viewpoint of energy, a silicone resin is preferable. The method for coating the core material with the resin is not particularly limited, for example, a method in which a coating material such as a resin is dissolved or suspended in a solvent and applied to the core material, or a method of simply mixing with a powder.

  In the two-component developer obtained by mixing the toner and the carrier, the toner to carrier weight ratio (toner / carrier) is preferably 1/99 to 10/90, and more preferably 2/98 to 8/92.

  Further, since the toner of the present invention is very excellent in low-temperature fixability and excellent in durability, an image forming method using a high-speed developing device having a linear speed of 750 mm / sec or more, preferably 850 to 2000 mm / sec. Also, it can be suitably used.

[Softening point (Tm) of resin, treated product and toner]
Using a flow tester (Shimadzu Corporation, CFT-500D), a 1 g sample was heated at a heating rate of 6 ° C / min, and a 1.96 MPa load was applied by a plunger and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. . The amount of plunger drop of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[Maximum peak temperature and glass transition temperature (Tg) of resin endotherm]
Using a differential scanning calorimeter (DSC Q20, manufactured by TA Instruments Japan), the sample was heated to 200 ° C and cooled to 0 ° C at a temperature decrease rate of 10 ° C / min. Increase the temperature at 10 ° C / min to obtain the maximum endothermic peak temperature. In addition, the glass transition point peculiar to the amorphous resin is the temperature at the intersection of the baseline extension line below the maximum endothermic peak temperature and the tangent line indicating the maximum slope from the peak rising part to the peak apex in the above measurement. And

[Glass transition point of treated product and toner]
Cooling to -20 ° C using a differential scanning calorimeter (manufactured by TA Instruments Japan Co., Ltd., DSCQ20), the endotherm when the temperature was raised from that temperature to 160 ° C at a heating rate of 10 ° C / min. The temperature at the intersection of the baseline extension below the maximum peak temperature and the tangent indicating the maximum slope from the peak rise to the peak apex.

[Acid value and hydroxyl value of resin]
Measured according to the method of JIS K0070. However, only the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070 to the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)). However, for crystalline polyester, chloroform was used as a measurement solvent.

[Melting point of wax]
Using a differential scanning calorimeter (DSCQ20, manufactured by TA Instruments Japan), the sample was heated to 200 ° C and cooled to 0 ° C at a temperature decrease rate of 10 ° C / min. The temperature is raised at ° C./min, and the maximum peak temperature of heat of fusion is taken as the melting point.

[Volume-median particle size of pulverized product and toner (D ₅₀ )]
Measuring machine: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 50μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
Electrolyte: Isoton II (Beckman Coulter, Inc.)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) 5% electrolyte dispersion condition: 10 mg of measurement sample is added to 5 ml of dispersion, and dispersed for 1 minute with an ultrasonic disperser. Then, 25 ml of the electrolytic solution is added, and further dispersed with an ultrasonic disperser for 1 minute.
Measurement conditions: Add 100 ml of electrolyte and dispersion in a beaker, measure 30,000 particles at a concentration that can measure the particle size of 30,000 particles in 20 seconds, and determine the volume-median particle size ( determine the D _50).

[Toner dielectric constant (ε) and dielectric loss tangent (tanδ)]
A pressure of 1.2 tons is applied to 5 g of toner for 10 seconds to prepare pellets having a smooth surface with a diameter of 60.0 mm and a thickness of 1.8 mm. When the obtained pellet was measured at 1 kHz in an environment with a temperature of 25 ° C. and a humidity of 50% using a region LCR meter “HP4284A” and a dielectric measurement electrode “HP16451B” (both manufactured by Yokogawa Hewlett Packard). Dielectric constant (ε) and dielectric loss tangent (tan δ) are adopted.

[Average circularity of toner]
Measuring machine: FPIA-3000 (manufactured by Sysmex Corporation)
Standard unit (10x objective lens)
Measurement mode HPF mode Version 00-10
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB13.6) 5% by weight Electrolyte dispersion condition: 10 mg of measurement sample was added to 10 ml of dispersion, and dispersed for 1 minute with an ultrasonic disperser. Thereafter, 10 ml of distilled water is added, and further dispersed for 2 minutes with an ultrasonic disperser.
Measurement conditions: Toner dispersed in a dispersion is measured at 20 ° C. at a concentration of 1800 to 2200 particles.

[Average particle size of external additives]
The average particle size of the external additive refers to the number average particle size. The particle size (average value of major axis and minor axis) of 500 particles is measured from a scanning electron microscope (SEM) photograph, and the average value is averaged. The particle size.

[Carrier saturation magnetization]
(1) Fill a plastic case with a lid of 7 mm outer diameter (6 mm inner diameter) and 5 mm height while tapping the carrier, and calculate the mass of the carrier from the difference between the weight of the plastic case and the weight of the plastic case filled with the carrier. .
(2) Set the plastic case filled with the carrier in the sample holder of the magnetic property measurement device `` BHV-50H '' (VSMAGNETOMETER) of RIKEN ELECTRONICS CO., LTD., While vibrating the plastic case using the vibration function, Saturation magnetization is measured by applying a magnetic field of 79.6 kA / m. The obtained value is converted into saturation magnetization per unit mass in consideration of the mass of the filled carrier.

Production Example 1 of Crystalline Polyester (Resin A)
The alcohol component, carboxylic acid component, esterification catalyst, and polymerization inhibitor shown in Table 1 were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple. After reacting over time, the temperature was raised to 200 ° C. and reacted for 1 hour, and further reacted at 8.3 kPa for 1 hour to obtain a crystalline polyester (resin A).

Production Example 2 of Crystalline Polyester (Resin B)
The alcohol component, carboxylic acid component, wax, esterification catalyst and polymerization inhibitor shown in Table 1 were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, and 160 ° C. Then, the mixture was reacted for 5 hours, heated to 200 ° C., reacted for 1 hour, and further reacted at 8.3 kPa for 1 hour to obtain a crystalline polyester (resin B).

Production Example 1 of Amorphous Polyester (Resin C)
The alcohol component, carboxylic acid component, esterification catalyst and polymerization inhibitor shown in Table 1 were put into a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and the temperature was raised to 230 ° C. The reaction was continued until the reaction rate reached 90%, and the reaction was further continued at 8.3 kPa for 1 hour to obtain Resin C. In the present invention, the reaction rate means a value of reaction water amount (mol) / theoretical product water amount (mol) × 100.

Production Example 2 of Amorphous Polyester (Resin D)
The alcohol components, terephthalic acid, dodecenyl succinic acid and esterification catalyst shown in Table 1 were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, and 230 ° C. under a nitrogen atmosphere. Then, the reaction was continued until the reaction rate reached 90%, followed by further reaction at 8.3 kPa for 1 hour. Thereafter, the mixture was cooled to 210 ° C., trimellitic anhydride shown in Table 1 was added, reacted at normal pressure for 1 hour, and then reacted until reaching the desired softening point at 8.3 kPa, thereby obtaining Resin D. . The reaction rate means a value of the amount of generated reaction water (mol) / theoretical generated water amount (mol) × 100.

Examples 1, 2, 5-8 and Comparative Examples 3, 4
100 parts by weight of binder resin shown in Table 2, 6 parts by weight of carbon black “NIPEX-60” (Degussa), 2 parts by weight of negative charge control agent “T-77” (Hodogaya Chemical Co., Ltd.) 2 parts by weight of the mold “Carnauba Wax C-1” (manufactured by Kato Yoko Co., Ltd.) was mixed for 60 seconds with a Henschel mixer. The obtained mixture was melt-kneaded with a twin-screw extruder, cooled, and then coarsely pulverized using a hammer mill so that the volume median particle size (D ₅₀ ) was about 1 mm. The obtained coarsely pulverized product was finely pulverized by an air jet type pulverizer and classified to obtain negatively charged toner base particles having a volume median particle size (D ₅₀ ) of 8.5 μm.

  The obtained toner base particles 100 parts by weight, hydrophobic silica `` R972 '' (manufactured by Nippon Aerosil Co., Ltd., average particle size 16 nm, hydrophobizing treatment DMDS) 0.9 part by weight and hydrophobic silica `` NAX50 '' (manufactured by Nippon Aerosil Co., Ltd., Toner (externally added toner) was obtained by mixing 1.0 part by weight of an average particle size of 40 nm and a hydrophobizing agent (HMDS) with a Henschel mixer for 3 minutes.

  The temperature of the externally added toner obtained was measured with an optical fiber thermometer, and Table 2 was used with a cavity type microwave reactor (manufactured by Shikoku Keiki Kogyo Co., Ltd., frequency: 2.45 GHz, maximum output: 1.5 kW). Microwave irradiation was performed under the conditions indicated.

Examples 3 and 4
A toner was obtained in the same manner as in Examples 1 and 2 except that the microwave irradiation was performed after coarse pulverization rather than after external addition.

Examples 9, 10
A toner was obtained in the same manner as in Examples 1 and 2 except that the microwave irradiation was performed after melt kneading instead of after external addition.

Comparative Examples 1 and 2
A toner was obtained in the same manner as in Examples 1 and 2 except that microwave irradiation was not performed.

Comparative Examples 5 and 6
A toner was obtained in the same manner as in Comparative Examples 3 and 4 except that microwave irradiation was not performed.

Test Example 1 [low temperature fixability]
6 parts by weight of toner and 94 parts by weight of ferrite carrier (volume average particle diameter: 60 μm, saturation magnetization: 68 Am ² / kg) were mixed to obtain a two-component developer. The obtained two-component developer is mounted on a copier “AR-505” (manufactured by Sharp), adjusted so that the toner adhesion amount is 0.6 mg / cm ² , and then the image is taken out before fixing. An unfixed image was obtained. Furthermore, using a non-contact fixing type image forming device "Vario stream 9000" (manufactured by Océ Printing Systems), an external fixing device is used, and the temperature on the paper is increased from 90 ° C to 150 ° C to 10 ° C. A fixed image was obtained by sequentially raising the image. "UNICEF Cellophane" (Mitsubishi Pencil Co., Ltd., width: 18mm, JISZ-1522) is pasted on the image fixed at each temperature, pressure is applied to the tape with a roller so that a load of 500g is applied, and then the tape is peeled off. The image density before and after peeling was measured. The temperature on the paper where the fixing rate (image density after tape peeling / image density before tape application × 100) first exceeded 90% was defined as the minimum fixing temperature. The paper used for the fixing test is a cardboard “CopyBond SF-70NA” (75 g / m ² ) manufactured by Sharp Corporation. The results are shown in Table 3.

Test Example 2 [storage stability]
5 g of toner was placed in a 50 ml polybin and left for 48 hours in an environment of a temperature of 50 ° C. and a relative humidity of 60%. Thereafter, the toner was sieved with a mesh having an opening of 100 μm, the residual toner on the mesh was weighed, and storage stability was evaluated according to the following evaluation criteria. The results are shown in Table 3.

〔Evaluation criteria〕
○: Residual toner is less than 0.5 g △: Residual toner is 0.5 g or more, less than 1 g ×: Residual toner is 1 g or more

Test Example 3 [Toner spent (durability)]
6 parts by weight of toner and 94 parts by weight of ferrite carrier (volume average particle diameter: 60 μm, saturation magnetization: 68 Am ² / kg) were mixed to obtain a two-component developer. The resulting two-component developer is mounted on a two-component development type image forming apparatus “Vario stream 9000” (manufactured by Ossprinting Systems), and after printing for 30 hours at a printing rate of 9% and a linear speed of 1000 mm / sec. The spent amount was measured according to the following method. The results are shown in Table 3.

(1) The two-component developer is passed through a mesh having a mesh size of 20 μm with a vacuum cleaner, and the carbon content of the remaining carrier is measured with a carbon analyzer (carbon analyzer: manufactured by HORIBA).
(2) The carrier whose carbon content is measured in (1) is washed with chloroform, and the toner adhering to the carrier is removed. After cleaning, the amount of carbon in the carrier is measured.
(3) The amount of spent toner is obtained by subtracting the amount of carbon measured in (2) from the amount of carbon measured in (1). In the table, it is expressed as% by weight relative to the weight of the carrier.

  From the above results, the toners obtained in Examples 1 to 10 are excellent in low-temperature fixability and storage stability as compared with the toners obtained in Comparative Examples 1 to 6, and have less toner spent and durability. It turns out that it is also favorable. In particular, Examples 1 and 2 using crystalline polyester and Comparative Examples 1 and 2 and Comparative Examples 3 and 4 using only amorphous polyester and Comparative Examples 5 and 6 were compared, respectively. It can be seen that the effect of improving the storage stability and suppressing the toner spent by irradiation is a remarkable effect peculiar to a crystalline resin not found in an amorphous resin.

  The electrostatic image developing toner obtained by the present invention is suitably used for developing a latent image formed by electrophotography, electrostatic recording method, electrostatic printing method and the like.

Claims (5)

  Melting and kneading the raw material of toner base particles containing a binder resin and a colorant containing a crystalline resin having a softening point to endothermic peak temperature ratio (softening point / endothermic peak temperature) of 0.6 to 1.3 A step of obtaining a melt-kneaded product, a step of pulverizing the obtained melt-kneaded product to obtain a pulverized product, a classifying step of classifying the obtained pulverized product to obtain toner base particles, and the obtained toner base particles and the outside A method for producing an electrostatic image developing toner comprising at least an external addition step of mixing an additive to obtain an external addition toner, further comprising a step of irradiating a processed product after the melt-kneading step with microwaves. A method for producing a toner for developing an electrostatic image.   The production method according to claim 1, wherein the crystalline resin is crystalline polyester.   The manufacturing method of Claim 1 or 2 which irradiates a processed material after a grinding | pulverization process with a microwave.   An electrostatic charge image developing toner obtained by the production method according to claim 1.   An image forming method, wherein the electrostatic image developing toner according to claim 4 is used in an image forming apparatus having a linear velocity of 750 mm / sec or more.