JP4133685B2 - Magnetic toner and manufacturing method thereof - Google Patents

Description

  The present invention relates to a magnetic toner used in an electrophotographic method, a copying machine using an electrostatic recording method, a printer, a fax machine, and the like, and a method of manufacturing the same.

  In an electrophotographic image forming apparatus, in order to perform high-speed fixing using a fixing device including a pressure roller and a heating roller, it is necessary to ensure lower temperature fixing properties. Conventionally, it has been studied to add various release agents from the viewpoint of achieving both fixing properties and image characteristics. In addition, in order to improve the fixing performance of the toner, in particular, offset resistance, many techniques for internally adding wax into the toner have been introduced. On the other hand, the performance is improved by this internal addition, but the blocking resistance is deteriorated. There have been problems such as a problem in matching with the image forming means or developability.

  Further, a technique of adding two or more kinds of waxes to the toner in order to exert the effect of adding wax from a low temperature region to a high temperature region at the time of fixing is also known. For example, Patent Document 1 discloses a polypropylene wax or a combination of polyethylene wax and paraffin wax, and Patent Document 2 includes two types of polyalkylene waxes having different melting points in which the melting point and the melting point temperature difference of each wax are defined. Is a combination of a polyalkylene wax having a specific molecular weight and a polyethylene wax having prescribed melt viscosity, molecular weight, acid value, etc., and Patent Document 4 discloses a combination of waxes each having a sharp melting peak. Discloses a combination of two waxes having different melt viscosities. However, none of these toners can satisfy all of the performances. For example, the toner is excellent in high temperature offset property and developability, but has problems such as poor low temperature fixing performance.

In Patent Document 6, two kinds of wax are contained in the magnetic toner, the average circularity of the toner particles is 0.960 or more, the magnetic powder is not exposed on the surface of the toner particles, and the wax is bonded as the wax. It has been proposed to use two types of waxes that are soluble and insoluble in the resin. However, since this toner actually has an average circularity of 0.960 or more obtained by a polymerization method, the fluidity is too good and the toner tends to be clogged relatively closely, particularly in high-speed fixing. Has a problem that a low temperature offset occurs. In addition, in the high-speed fixing, the fixing performance from the low temperature region to the high temperature region is insufficient.
Japanese Patent Publication No.52-3305 JP 58-215659 A JP-A-4-124676 JP-A-8-334920 Japanese Patent Laid-Open No. 10-104835 Japanese Patent Laid-Open No. 2002-202627

  In view of the above problems, the object of the present invention is to generate no low temperature offset even in high-speed fixing, have excellent fixing performance from a low temperature region to a high temperature region, have blocking resistance, and in a high temperature and high humidity environment. Another object of the present invention is to provide a magnetic toner capable of forming a stable image over a long period of time without causing a decrease in image density, toner adhesion to a photoreceptor, and image fogging.

  In order to achieve the above object, the inventors of the present invention have disclosed a low-temperature offset in a magnetic toner used in an image forming apparatus for high-speed fixing that includes a heat roller fixing device having a peripheral speed of a fixing roller of 300 to 450 mm / sec. Excellent fixing performance from low temperature to high temperature, blocking resistance, image density does not decrease even in high temperature and high humidity environment, and toner adhesion and image fogging are not observed. Intensive study was conducted so that a stable image could be formed over a long period of time. As a result, by setting the average circularity of the toner particles to 0.95 to 0.96, while maintaining the image quality, the toner particles are slightly sparse so that the toner amount is reduced and low temperature fixability is obtained. I found out that I can. If the average circularity is larger than this range, the toner particles tend to be densely clogged and the amount of toner increases, so that the amount of heat is required and the fixing property is weakened. On the other hand, if the average circularity is smaller than this range, the image quality deteriorates. . Furthermore, by using a polyester resin as the main component of the binder resin, sufficient fixing performance can be obtained even with a low heat quantity, and blocking resistance can be ensured. Further, by using a wax having an endothermic peak in differential thermal analysis (DSC) of (A) 70 ° C. to 85 ° C., fixing performance in a low temperature region is obtained (preventing low temperature fsetting), and (B) 130 ° C. to 150 ° C. It has been found that fixing performance (prevention of high temperature offset) in a high temperature region can be secured by using wax. Furthermore, it has also been found that the magnetic toner according to the present invention can be obtained by a pulverization method so that a high-speed fixing property can be obtained. The present invention has been completed by further studies based on these findings.

That is, the present invention provides the following magnetic toner and a method for producing the same.
1) A toner used in an image forming apparatus including a developing device that develops and visualizes toner on an electrostatic latent image formed on an image carrier, and a fixing device including a pressure roller and a heating roller. ,
The toner is for high-speed fixing at a fixing roller peripheral speed of 300 to 450 mm / sec, contains at least a binder resin mainly composed of a polyester resin, magnetic powder, and wax, and has an average circularity of the toner particles. 0.95 to 0.96, and the wax is a two-component wax having an endothermic peak in differential thermal analysis in the range of (A) 70 to 85 ° C. and (B) 130 to 150 ° C. A magnetic toner comprising 100 parts by weight and 20 to 70 parts by weight of wax (B) .
2) The magnetic toner according to 1) above, wherein one of the wax components is polypropylene wax, and the polypropylene wax is contained in an amount of 1 to 3 parts by weight with respect to 100 parts by weight of the binder resin.

3 ) High-speed fixing toner used in an image forming apparatus including a developing device that develops and visualizes toner on an electrostatic latent image formed on an image carrier, and a fixing device including a pressure roller and a heating roller. In the production of a binder resin having a polyester resin as a main component, a magnetic powder, and two components having endothermic peaks in differential thermal analysis in the ranges of (A) 70 to 85 ° C. and (B) 130 to 150 ° C. Is melt-kneaded in a ratio of 100 parts by weight of wax (A) and 20-70 parts by weight of wax (B) , and the resulting melt-kneaded product is cooled and ground to obtain an average circularity of 0.95 to 0. 0. A method for producing a magnetic toner, comprising obtaining 96 toner particles.

  The magnetic toner of the present invention is suitable for high-speed fixing at a fixing roller peripheral speed of 300 to 450 mm / sec, does not generate a low temperature offset, has excellent fixing performance from a low temperature region to a high temperature region, and also has blocking resistance. Even under a high-temperature and high-humidity environment, the image density does not decrease, toner adhesion to the photoreceptor and image fogging do not occur, and a stable image can be formed over a long period of time. In the magnetic toner of the present invention, the effect of low temperature offset and high temperature offset can be obtained by using polypropylene wax as one of the wax components. Further, in the magnetic toner of the present invention, by using an amorphous silicon drum as the image carrier, it is possible to more effectively prevent toner adhesion to the surface of the image photoreceptor. The method for producing a magnetic toner according to the present invention is useful for obtaining the toner having the above properties, and can produce toner particles having an average circularity of 0.95 to 0.96 in spite of employing the pulverization method.

  An image forming apparatus using an electrophotographic system charges an image carrier (electrophotographic photosensitive member) (main charging process), and exposes an image to form an electrostatic latent image (exposure process). The toner is developed with a developing bias voltage applied (development process), and the formed toner image is transferred to a transfer sheet (transfer process) and fixed to form an image. Usually, the residual toner on the photoconductor is cleaned by a urethane blade or the like (cleaning process), and the residual charge on the photoconductor is erased by an LED or the like (static elimination process). The present invention provides a magnetic toner suitable for high-speed fixing in which the peripheral speed of the pressure roller and heating roller for fixing is 300 to 450 mm / sec in the image forming apparatus.

  A medium / low speed image forming apparatus (fixing speed: 100 to 250 mm / sec) has a wide nip width at the fixing portion and is advantageous for fixing toner, but a high speed image forming apparatus (fixing speed: 300 to 450 mm / sec). In this case, the nip width of the fixing portion becomes narrow, which adversely affects toner fixing. When the magnetic toner of the present invention is used, low-temperature offset does not occur even in a high-speed image forming apparatus that is disadvantageous for toner fixing, and excellent fixing performance is exhibited.

  Examples of the image carrier (electrophotographic photosensitive member) include a rotating drum type OPC photosensitive member and an amorphous silicon photosensitive member. The magnetic toner of the present invention can suppress adhesion more greatly when an amorphous silicon drum is used. Can do. That is, in the case of an amorphous silicon drum, since the surface of the photoconductor has a large hardness and is extremely excellent in wear resistance as compared with the organic photoconductor drum, for example, inorganic fine particles such as silica, alumina, and titanium oxide are used as the toner. When externally added to the surface, these inorganic fine particles exhibit an action of polishing the surface of the photoconductor, thereby preventing toner adhesion to the surface of the photoconductor more advantageously.

The magnetic toner of the present invention contains at least a binder resin mainly composed of a polyester resin, magnetic powder, and wax. In the magnetic toner of the present invention, the binder resin is contained in an amount of 30 to 60% by weight, preferably 40 to 50% by weight in the total amount of the toner. The proportion of each component is 20 to 70 parts by weight, preferably 30 to 50 parts by weight, and the wax is 3 to 10 parts by weight, preferably 100 parts by weight of the binder resin. The ratio is 5 to 7 parts by weight. Here, the wax contains two components having endothermic peaks in DSC in the ranges of (A) 70 to 85 ° C. and (B) 130 to 150 ° C., and the combination of the wax (A) and the wax (B) The proportion is 20 to 70 parts by weight, preferably 30 to 50 parts by weight of (B) with respect to 100 parts by weight of (A). Hereinafter, the respective components will be described in order. First, the wax internally added to the magnetic toner of the present invention will be described. Waxes can be classified into (a) 70 ° C. to 85 ° C., (b) 86 ° C. to 129 ° C., and (c) 130 ° C. to 150 ° C., depending on the size of the endothermic peak when differential thermal analysis is performed. According to the present inventors, it has been found that when these ranges of wax are internally added to the magnetic toner, the influence on the properties differs as follows.

  First, when only a wax having an endothermic peak in the range (a) (low melting point wax) is internally added, the low-temperature fixability is good, but the offset resistance at high temperatures is poor. Increasing the amount of internal addition improves the low-temperature fixability, but lowers the Tg of the toner and deteriorates the blocking resistance. As a result, developability in a high-temperature and high-humidity environment deteriorates, the image density decreases, the charging performance is affected, and fogging increases. When only a wax having an endothermic peak in the range of (b) is internally added, a satisfactory fixing performance can be obtained in a somewhat wide temperature range, but in a low temperature range (for example, a fixing temperature of 130 ° C.) which is the object of the present invention. A low temperature offset occurs, and a high temperature offset also occurs in a high temperature region (for example, a fixing temperature of 220 ° C.). Further, when only a wax having an endothermic peak in the range of (c) is internally added, there is no problem with offset resistance at high temperatures, but satisfactory low-temperature fixing performance cannot be obtained. Further, when the amount of internal addition is increased, it tends to adhere to the drum.

As described above, since there are advantages and disadvantages even if one type of wax is internally added to the magnetic toner, the present inventors have studied paying attention to using two types of wax together.
When two kinds of waxes satisfying the endothermic peak ranges (a) and (b) are internally added, the low-temperature fixability is relatively good, but the offset resistance at high temperatures is poor. The blocking resistance also deteriorates, the developability in a high temperature and high humidity environment is not sufficient, and the image density is low. Moreover, when the amount of wax is increased too much, fogging increases in a high temperature and high humidity environment. In addition, when two types of waxes in the range of (b) and (c) are internally added, there is no problem with offset resistance at high temperatures, but satisfactory fixing performance cannot be obtained. Further, since the wax is not dispersed, it easily adheres to the drum.

  However, when two types of waxes in the range of (a) and (c) are internally added, the fixing performance, blocking resistance, and developability in a high-temperature and high-humidity environment from the low-temperature region to the high-temperature region, which is the object of the present invention, In addition, it is possible to obtain a very advantageous effect that there is no particular problem with toner adhesion to the photosensitive drum. It is considered that the dispersibility of the wax is improved by adding a high melting point wax such as polypropylene wax as compared with the case where only the low melting point wax is internally added. This is probably due to the dispersion of low melting point wax with polypropylene wax as the core.

  Examples of the wax having a DSC endothermic peak at 70 ° C. to 85 ° C. include plant waxes such as ester wax, carnauba wax, rice wax, and candelilla wax. Examples of the wax having a DSC endothermic peak at 130 ° C. to 150 ° C. include olefin waxes such as synthetic polyethylene and synthetic polyolefin.

  The binder resin contained in the magnetic toner of the present invention is mainly composed of a polyester resin in terms of development characteristics, fixing properties, etc., and the amount of the polyester resin in the total amount of the binder resin is 50% by weight or more, preferably 60%. % By weight or more, more preferably 80% by weight or more. As the binder resin that can be used together with the polyester resin, as in the past, styrene such as polystyrene and polyvinyltoluene, and homopolymers of substituted products thereof; styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinyl Naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer Polymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer Coalescence, styrene-vinylethyl Styrene copolymer such as ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer Combined; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyamide resin, epoxy resin, polyacrylic acid resin, rosin, modified rosin, temper resin, phenol resin, aliphatic or fat A cyclic hydrocarbon resin, an aromatic petroleum resin, or the like can be used alone or in combination.

In the present invention, the glass transition temperature (Tg) of the binder resin is preferably 50 to 70 ° C. When the Tg is lower than 50 ° C., the storage stability of the magnetic toner tends to be lowered, and when it is higher than 70 ° C., the fixability tends to be inferior.
The magnetic toner of the present invention needs to contain magnetic powder in the toner particles. The magnetic powder itself can be the same as the conventional one. For example, it may contain elements such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, silicon, etc., and is composed mainly of iron oxide, such as triiron tetroxide, γ-iron oxide, etc. Or two or more types are used in combination. These magnetic powders preferably have a BET specific surface area of ² to 30 m ² / g, particularly 3 to 28 m ² / g, and a Mohs hardness of 5 to 7 by the nitrogen adsorption method.

  The shape of the magnetic powder includes octahedrons, hexahedrons, spheres, needles, flakes, and the like, but those having less anisotropy such as octahedrons, hexahedrons, spheres, and irregular shapes increase the image density. Preferred above. The shape of such magnetic powder can be confirmed by, for example, SEM (scanning electron microscope). The volume average particle size of the magnetic powder is preferably 0.01 to 1.0 μm, more preferably 0.05 to 0.5 μm. When the volume average particle diameter of the magnetic powder is less than 0.01 μm, the decrease in blackness becomes remarkable, the coloring power is insufficient as a colorant for black and white toner, and the composite oxide particles are aggregated. Since it becomes strong, the dispersibility tends to deteriorate. On the other hand, if the volume average particle size exceeds 1.0 μm, the coloring power may be insufficient as in the case of a general colorant. In addition, particularly when used as a colorant for small-diameter toner, it is probabilistically difficult to disperse the same number of magnetic particles in individual toner particles, and the dispersibility tends to deteriorate.

  In addition, as a measuring method of the average particle diameter (ferret diameter) of the magnetic powder, in a field of view with a 30,000 times magnification photograph in a transmission electron microscope (TEM) with the magnetic powder sufficiently dispersed. And measuring the particle diameter of 100 magnetic powders. The magnetic powder used in the magnetic toner of the present invention is preferably surface-treated by hydrolyzing a coupling agent in an aqueous medium.

Magnetic powder, as in the prior art, the magnetic properties, the magnetic field 795.8 kA / m under the saturation magnetization is 10~200Am ² / kg, residual magnetization 1~100Am ² / kg, the coercive force 1～30KA / What is m is preferable. As described above, the blending ratio of the magnetic powder used in the magnetic toner of the present invention is preferably in the range of 20 to 70 parts by weight, preferably 30 to 50 parts by weight with respect to 100 parts by weight of the binder resin. If it is a range, it is still more preferable. Below this range, the coloring power of the magnetic toner is poor and fogging is difficult to suppress. On the other hand, if this range is exceeded, the retention force due to the magnetic force on the toner carrier increases and the developability deteriorates, and it is difficult to uniformly disperse the magnetic powder into individual toner particles, and the fixability tends to decrease. is there.

  The magnetic powder may be produced according to a method known per se, and an example thereof is as shown in Reference Example 1 described later. In the magnetic toner of the present invention, a charge control agent can be blended in order to stabilize the charge characteristics. As the charge control agent, a known one can be used, and it may be selected based on the fact that the charging speed is fast and that a constant charge amount can be stably maintained. As a specific compound, as a negative charge control agent, Metallic compounds of aromatic carboxylic acids such as salicylic acid, alkylsalicylic acid, dialkylsalicylic acid, naphthoic acid and dicarboxylic acid, metal salts or metal complexes of azo dyes or azo pigments, polymer types having sulfonic acid or carboxylic acid groups in the side chain Known compounds such as compounds, boron compounds, urea compounds, silicon compounds, calixarene and the like can be mentioned. Further, examples of the positive charge control agent include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, a nigrosine compound, and an imidazole compound. The method of adding the charge control agent to the toner may be either a method of adding the toner inside the toner particles or a method of adding it externally.

The amount of these charge control agents used is generally 3 to 20 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of the binder resin. The determination may be made in consideration of the presence or absence of other additives and the magnetic toner production method including the dispersion method.
In addition to the magnetic powder, other colorants may be used in combination with the magnetic toner of the present invention according to a conventional method. Examples of the coloring material include magnetic or nonmagnetic inorganic compounds, known dyes and pigments, and specific examples thereof include ferromagnetic metal particles such as cobalt and nickel, or chromium, manganese, copper, zinc, and the like. , Aluminum, alloys added with rare earth elements, particles of hematite, titanium black, nigrosine dye, carbon black, phthalocyanine, and the like.

  Next, the magnetic toner of the present invention requires that the toner particles have an average circularity of 0.95 to 0.96. The average circularity referred to here is used as a simple method for quantitatively expressing the shape of the particles, and is an index of the degree of unevenness of the magnetic toner (see Patent Document 6). In the present invention, by setting the average circularity within the above range, the contact area between the toner particles and the image carrier is small, the adhesion of the toner particles to the image carrier is reduced, and the transfer rate is increased. Further, since the residual toner after transfer is reduced, the amount of magnetic toner at the contact portion between the charging member and the image carrier is very small, toner fusion is prevented, and image defects are remarkably suppressed.

  The average circularity can be measured according to a known method, for example, a method described in Patent Document 6. To measure the average circularity, a flow particle image analyzer “FPIA-1000” manufactured by Toago Medical Electronics can be used. In the measurement, the average circularity of a particle group having an equivalent circle diameter of 3 μm or more is obtained. As a specific method for measuring the average circularity and the mode circularity when using the above apparatus, about 5 mg of magnetic toner is dispersed in 10 mL of water in which about 0.1 mg of a surfactant is dissolved to prepare a dispersion. Then, ultrasonic waves (20 KHz, 50 W) were irradiated to the dispersion for 5 minutes, the dispersion concentration was set to 5000 to 20,000 / μL, and the measurement was performed with the above-described apparatus, and the average circularity of a particle group having an equivalent circle diameter of 3 μm or more And determine the mode circularity.

In addition, in “FPIA-1000”, which is the measuring apparatus, after calculating the circularity of each particle, the average circularity and the mode circularity are calculated. .00 is divided into 61 classes, and a calculation method is used in which the average circularity is calculated using the center value and frequency of the division points.
The volume average particle diameter of the magnetic toner of the present invention is generally 3 to 10 μm, preferably 4 to 8 μm. By adjusting to this range, the image quality can be improved, and minute latent image dots can be accurately developed.

  Although known methods such as a pulverization method and a polymerization method are known for the production of toner particles, the magnetic toner of the present invention is produced by a pulverization method. That is, the binder resin, the magnetic powder and the wax two components and, if necessary, the charge control agent and other additives are premixed with a Henschel mixer or the like, then melt-kneaded with a twin screw extruder or the like, cooled, Grind and classify to obtain an average circularity of 0.95 to 0.96. For crushing, for example, machines such as Kawasaki Heavy Industries' Cebros, Kryptron, Turbo Industry's turbo mill, Nippon Pneumatic Industry's fine mill, Hosokawa Micron's inomizer, Japan Engineering's Super Rotor, etc. It is preferable to use a type pulverizer, and a toner having a higher sphericity than that using an air type pulverizer can be obtained. In particular, by using a turbo mill manufactured by Turbo Industries, a toner having a desired average circularity can be obtained efficiently. According to the conventional pulverization method, the average circularity is about 0.94, but according to the present invention, the average circularity of 0.95 to 0.96 can be obtained even though the pulverization method is adopted. .

  The magnetic powder may be surface-modified, for example, Japanese Patent Application Laid-Open No. 59-200244, Japanese Patent Application Laid-Open No. 59-200266, Japanese Patent Application Laid-Open No. 59-200237, Japanese Patent Application Laid-Open No. 59-224102. And a method of treating silicon element-containing magnetic particles disclosed in JP-A-63-250660 with a silane coupling agent. Specifically, as shown in the examples described later, after dispersing the magnetic powder in an aqueous medium, adding a silane coupling agent while stirring, performing a coupling treatment, washing, filtering, and drying Is mentioned.

  Normally, toner particles closer to a spherical shape are obtained by the polymerization method. For toners having an average circularity of 0.96 or more, blocking resistance, developability in a high-temperature and high-humidity environment, and toner adhesion to the photoreceptor are particularly problematic. Is not seen. However, since the fluidity is good and the toner particles are relatively close to each other and the nip width of the fixing portion is narrow, high-speed fixing is difficult to transfer heat in a low temperature region (for example, fixing temperature: 130 ° C.), and low temperature offset is caused. appear. On the other hand, according to a simple pulverization method, a toner having an average circularity of about 0.94, which is not relatively round, can be obtained. However, this toner has poor developability in a high-temperature and high-humidity environment and has a low image density. Since the magnetic toner of the present invention contains the two-component wax as described above, it can be obtained at a low temperature by obtaining a toner having a specific circularity of 0.95 to 0.96 by a pulverization method. High-speed fixing from the region to the high temperature region is possible.

  As described above, according to the present invention, the developing device filled with the toner for visualizing the electrostatic latent image formed on the electrophotographic photosensitive member and the high speed of the heat roller having the peripheral speed of the fixing roller of 300 to 450 mm / sec. An image forming apparatus including a fixing device includes at least a binder resin, a magnetic powder, and a wax component, an average circularity of 0.95 to 0.96, and a main component of the binder resin is a polyester resin. The present invention provides a magnetic toner containing two kinds of waxes having endothermic peaks in the differential thermal analysis of each wax in the range of (A) 70 ° C. to 85 ° C. and (B) 130 ° C. to 150 ° C. By using this magnetic toner, it has excellent fixing performance from low temperature to high temperature, and has good blocking resistance, that is, preservability, and image density does not decrease even in high temperature and high humidity environments, and the toner adheres to the photoreceptor. A stable image can be formed over a long period of time without fog or fog.

Hereinafter, the present invention will be described more specifically with reference to reference examples, examples and comparative examples.
The wax used for the production of each toner is shown in [Table 1], and the evaluation results of Examples and Comparative Examples are shown in [Table 2].
Reference example 1
[Manufacture of binder resin]
Bisphenol A propylene oxide 2.2 mol adduct (2000 g), bisphenol A ethylene oxide 2.2 mol adduct (800 g), terephthalic acid (500 g), n-dodecenyl succinic acid (600 g), trimellitic anhydride (350 g), Dibutyltin oxide (4 g) was reacted at 220 ° C. for 8 hours under a nitrogen atmosphere, and then reacted at a softening point of 155 ° C. under reduced pressure to obtain Resin A. In addition, bisphenol A propylene oxide 2.2 mol adduct (2800 g), terephthalic acid (400 g), fumaric acid (650 g), and dibutyltin oxide (4 g) were reacted at 220 ° C. for 8 hours in a nitrogen atmosphere, and then reduced in pressure. Resin B was obtained by the reaction under which the softening point reached 90 ° C.

Reference example 2
[Manufacture of magnetic powder]
An aqueous solution containing ferrous hydroxide was prepared by mixing 1.0 to 1.1 equivalents of a caustic soda solution with respect to iron ions in an aqueous ferrous sulfate solution. Air was blown in while maintaining the pH of the aqueous solution at around 9, and an oxidation reaction was performed at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals. Subsequently, after adding ferrous sulfate aqueous solution to this slurry liquid so that it may become 0.9-1.2 equivalent with respect to the original amount of alkalis (sodium component of caustic soda), the slurry liquid is maintained at pH 8, and air is supplied. While blowing, the oxidation reaction was promoted, and the magnetic iron oxide particles produced after the oxidation reaction were washed, filtered and once taken out. At this time, a small amount of water-containing sample was collected and the water content was measured. Then, after re-dispersed in a different aqueous medium without drying the water-containing sample to adjust the pH of the redispersion liquid to about 6, sufficiently stirring a silane coupling agent [n-C ₁₀ H ₂₁ 1.0 part by mass of Si (OCH ₃ ) ₃ ] was added to the magnetic iron oxide (the amount of magnetic iron oxide was calculated as a value obtained by subtracting the water content from the water-containing sample), and a coupling treatment was performed. The produced hydrophobic iron oxide particles were washed, filtered and dried by a conventional method, and then the slightly agglomerated particles were crushed to obtain a magnetic powder.

Toner production example 1
100 parts by weight of binder resin [60 parts by weight of polyester resin A (high molecular weight), 40 parts by weight of polyester resin B (low molecular weight)], 80 parts by weight of magnetic powder (average particle size: 0.20 μm), charge control agent [Styrene acrylic quaternary ammonium salt; trade name “FCA222P”, manufactured by Fujikura Kasei Co., Ltd.] 10 parts by weight, polypropylene wax [trade name “Yumex 100TS”, manufactured by Sanyo Kasei, maximum value of endothermic peak in DSC : 140 ° C.] 2.0 parts by weight, ester wax [trade name “Carnauba Wax No. 1” manufactured by Hiroyuki Kato, maximum value of endothermic peak in DSC: 82 ° C.] 4.0 parts by weight After premixing with a Henschel mixer, the mixture was melt kneaded using a twin screw extruder. After this melt-kneaded product was cooled, it was pulverized and classified by a mechanical pulverizer (turbo mill) to obtain toner particles having an average circularity of 0.955 and a volume average particle diameter of 7.2 μm. Next, 0.8 parts by weight of hydrophobic silica (trade name “TG820F”, manufactured by Cabot Corporation) was externally added to 100 parts by weight of the toner particles, and mixed with a Henschel mixer to obtain toner A. .

Toner production example 2
In the formulation of Toner Production Example 1, 3 parts by weight of an ester wax (maximum endothermic peak in DSC: 71 ° C., trade name “WE-3”, manufactured by Nippon Oil & Fats) and polypropylene wax had an endothermic peak in DSC. Maximum value: 132 ° C., weight average molecular weight 8000) Except for changing to 1 part by weight, the same procedure as in Toner Production Example 1 was carried out to obtain toner particles having a volume average particle diameter of 7.0 μm. Then, 0.8 part by weight of hydrophobic silica (TG820F) was externally added and mixed with a Henschel mixer to obtain a toner J having an average circularity of 0.960.

Toner production example 3
Toner particles having a volume average particle size of 7.0 μm were obtained in the same manner as in Toner Production Example 2 except that the amount of polypropylene wax added in the formulation of Toner Production Example 2 was changed to 3 parts by weight. By adding 0.8 part by weight of hydrophobic silica (TG820F) to 100 parts by weight and mixing with a Henschel mixer, toner C having an average circularity of 0.950 and toner having an average circularity of 0.960 K was obtained.

Toner production example 4
In the formulation of Toner Production Example 2, polypropylene wax was changed to 1 part by weight with a maximum endothermic peak of DSC of 150 ° C. and an average weight molecular weight of 9000. Then, toner particles having a volume average particle diameter of 7.0 μm are obtained, and 0.8 parts by weight of hydrophobic silica (TG820F) is externally added to 100 parts by weight of the toner particles and mixed with a Henschel mixer, thereby obtaining an average circular shape. A toner L having a degree of 0.958 was obtained.

Toner production example 5
The toner particles having a volume average particle size of 7.0 μm were obtained in the same manner as in Toner Production Example 4 except that the polypropylene wax was changed to 3 parts by weight in the formulation of Toner Production Example 4, and 100 parts by weight of toner particles were obtained. In contrast, 0.8 part by weight of hydrophobic silica (TG820F) was externally added and mixed with a Henschel mixer to obtain toner E having an average circularity of 0.950 and toner M having an average circularity of 0.960. It was.

Toner Production Example 6
Toner particles having a volume average particle diameter of 7.0 μm are the same as in Toner Production Example 2 except that the ester wax is changed to “TOA201 (G)” (maximum endothermic peak in DSC: 84 ° C., manufactured by Toa Kasei). The toner F having an average circularity of 0.951 and an average circularity was obtained by adding 0.8 part by weight of hydrophobic silica (TG820F) to 100 parts by weight of the toner particles and mixing with a Henschel mixer. Toner N of 0.959 was obtained.

Toner production example 7
A toner particle having a volume average particle diameter of 7.0 μm is obtained in the same manner as in Toner Production Example 6 except that the number of polypropylene wax parts is changed to 3 parts by weight. Hydrophobic silica (TG820F) is obtained with respect to 100 parts by weight of the toner particles. Was added externally and mixed with a Henschel mixer to obtain a toner G having an average circularity of 0.950 and a toner O having an average circularity of 0.956.

Toner production example 8
In the toner production example 6, the same procedure as in the toner production example 7 except that the polypropylene wax (DSC 132 ° C.) is changed to 1 part by weight of the polypropylene wax (maximum endothermic peak in DSC: 150 ° C., weight average molecular weight: 9000). Thus, toner particles having a volume average particle diameter of 7.2 μm were obtained, 0.8 parts by weight of hydrophobic silica (TG820F) was externally added to 100 parts by weight of the toner particles, and the mixture was mixed with a Henschel mixer. Toner P having a circularity of 0.960 was obtained.

Toner Production Example 9
Except for changing the number of parts of the polypropylene wax to 3 parts by weight, the same procedure as in Toner Production Example 8 was carried out to obtain toner particles having a volume average particle diameter of 7.2 μm. To 100 parts by weight of the toner particles, hydrophobic silica ( Externally adding 0.8 part by weight of TG820F) and mixing with a Henschel mixer, Toner I with an average circularity of 0.952 and Toner Q with an average circularity of 0.957 were obtained.

Toner Production Example 10
Toner production, except that the number of ester wax parts was changed to 3 parts by weight, and the polypropylene wax was changed to 1.5 parts by weight of polyethylene wax [trade name “Polywax 725”, manufactured by Toyo Petrolite, maximum value of endothermic peak in DSC: 102 ° C.] In the same manner as in Example 1, toner particles having a volume average particle diameter of 7.2 μm are obtained, 0.8 parts by weight of hydrophobic silica (TG820F) is externally added to 100 parts by weight of the toner particles, and mixed with a Henschel mixer. As a result, a toner R having a volume average particle diameter of 7.2 μm and an average circularity of 0.958 was obtained.

Toner Production Example 11
A toner particle having a volume average particle size of 7.2 μm was obtained in the same manner as in Toner Production Example 10 except that the ester wax was not used and the polyethylene wax was changed to 5 parts by weight. Toner S having an average circularity of 0.956 was obtained by externally adding 0.8 part by weight of functional silica (TG820F) and mixing with a Henschel mixer.

Toner Production Example 12
Toner having a volume average particle diameter of 7.2 μm is the same as toner production example 1 except that the wax component in the formulation of toner production example 1 is changed to 5 parts by weight of polyethylene wax (“polywax 725”). Particles were obtained, 0.8 part by weight of hydrophobic silica (TG820F) was externally added to 100 parts by weight of the toner particles, and mixed with a Henschel mixer to obtain toner T having an average circularity of 0.955. .

Toner Production Example 13
In the formulation of Toner Production Example 2, toner particles having a volume average particle diameter of 7.0 μm were obtained in the same manner as in Toner Production Example 2 except that 5 parts by weight of ester wax and polypropylene wax were not used. Toner U having an average circularity of 0.958 was obtained by adding 0.8 part by weight of hydrophobic silica (TG820F) to 100 parts by weight of toner particles and mixing with a Henschel mixer.

Toner Production Example 14
In the same manner as in Toner Production Example 1, except that ester wax is not used and polypropylene wax is changed to 4 parts by weight, toner particles having a volume average particle diameter of 7.0 μm are obtained in the same manner as in Toner Production Example 1. Toner V having an average circularity of 0.952 was obtained by externally adding 0.8 part by weight of hydrophobic silica (TG820F) to 100 parts by weight of particles and mixing with a Henschel mixer.

Toner Production Example 15
Ester wax (maximum endothermic peak in DSC: 71 ° C., trade name “WE-3”, manufactured by Nippon Oil & Fats) 3 parts by weight, polyethylene wax (“polywax 725”) 3 parts by weight, polypropylene wax ( The maximum endothermic peak in DSC: 140 ° C., “Yumex 100TS” (manufactured by Sanyo Kasei) was changed to 3 parts by weight, and all toner particles having a volume average particle diameter of 7.2 μm were obtained in the same manner as in Toner Production Example 1. As a result, 0.8 part by weight of hydrophobic silica (TG820F) was externally added to 100 parts by weight of the toner particles, and mixed with a Henschel mixer to obtain toner W having an average circularity of 0.952.

Toner Production Example 16
Toner Production Example 15 except that no ester wax was used and the number of parts of polypropylene wax (maximum endothermic peak in DSC: 140 ° C., “Yumex 100TS”, manufactured by Sanyo Kasei) was changed to 1.5 parts by weight. Similarly, toner particles having a volume average particle diameter of 7.2 μm are obtained, 0.8 parts by weight of hydrophobic silica (TG820F) is externally added to 100 parts by weight of the toner particles, and mixed with a Henschel mixer. A toner X having an average circularity of 0.954 was obtained.

Toner Production Example 17
Toner Y having a volume average particle size of 7.0 μm and an average sphericity of 0.970 was prepared in the same manner as in Toner Production Example 2, except that the ester wax part was changed to 3 parts by weight and the polypropylene wax part was changed to 1.5 parts by weight. Obtained.
Toner Production Example 18
A toner Z having a volume average particle diameter of 7.0 μm and an average circularity of 0.945 was obtained in the same manner as in Toner Production Example 17 except that Umex 100TS (DSC endothermic peak: 140 ° C.) was used as the polypropylene wax.

Toner Production Example 19
A toner AE having a volume average particle size of 7.4 μm and an average circularity of 0.957 was prepared in the same manner as in Toner Production Example 8 except that the ester wax part was 3 parts by weight and the polypropylene wax part was 0.5 parts by weight. Obtained.
Toner Production Example 20
A toner AF having a volume average particle diameter of 7.2 μm and an average circularity of 0.959 was obtained in the same manner as in Toner Production Example 8 except that the number of polypropylene wax parts was changed to 3.5 parts by weight.

Toner Production Example 21
Except for changing the ester wax WE-3 to 3 parts by weight of paraffin wax (maximum endothermic peak in DSC: 69 ° C., weight average molecular weight 410) and the number of polypropylene wax parts to 1.5 parts by weight, the same as in Toner Production Example 2. Thus, a toner AA having a volume average particle diameter of 7.2 μm and an average circularity of 0.950 was obtained.

Toner Production Example 22
Example of toner production except that 3 parts by weight of Carnauba purified product 1 (maximum value of endothermic peak in DSC: 86 ° C., manufactured by Nippon Seiki Co., Ltd.) is used as ester wax, and the number of parts of polypropylene wax is changed to 1.5 parts by weight. In the same manner as in Example 4, a toner AB having a volume average particle diameter of 7.2 μm and an average circularity of 0.960 was obtained.

Toner Production Example 23
Volume average particle size is the same as in Toner Production Example 2 except that the polypropylene wax is changed to 1.5 parts by weight of polyethylene wax LEL400P (EX) (maximum endothermic peak in DSC: 128 ° C., Sanyo Chemical Co., Ltd.). A toner AC having a diameter of 7.0 μm and an average circularity of 0.960 was obtained.

Toner Production Example 24
The volume average particle diameter is 7.2 μm in the same manner as in Toner Production Example 6 except that polypropylene wax is changed to 1.5 parts by weight of Biscol 550P (maximum endothermic peak in DSC: 153 ° C., manufactured by Sanyo Chemical Co., Ltd.). A toner AD having an average circularity of 0.956 was obtained.
Toner Production Example 25
[Toner production by polymerization method]
After warming the 0.1M-Na ₃ PO ₄ aqueous solution 451g to put to 60 ° C. in deionized water 709 g, water containing Ca3 (PO4) 2 was slowly added 1.0 M-CaCl ₂ aqueous solution 67.7g A medium was obtained. 80 parts by weight of styrene, 20 parts by weight of n-butyl acrylate, 1 part by weight of positive charge control agent (Bontron N-07), 90 parts by weight of magnetic powder (1) attritor (Mitsui Miike Chemical Co., Ltd.) Was uniformly dispersed and mixed. This monomer composition was heated to 60 ° C., 5 parts by weight of ester wax WE-3 (maximum endothermic peak in DSC: 71 ° C., manufactured by NOF Corporation) and polyester wax “YUMEX 100TS” (endothermic peak in DSC). The maximum value of: 140 ° C., manufactured by Sanyo Chemical Co., Ltd.) 5 parts by weight was added, mixed and dissolved, and the polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) [t 1/2 = 140 minutes, 60 5 ° C] was dissolved. The polymerizable monomer system was put into the aqueous medium, and the mixture was granulated by stirring at 10,000 rpm for 15 minutes with a TK type homogenizer at 60 ° C. in an N ₂ atmosphere. Thereafter, the mixture was reacted at 60 ° C. for 6 hours while stirring with a paddle stirring blade. Thereafter, the liquid temperature was raised to 80 ° C., and stirring was further continued for 4 hours. After completion of the reaction, distillation was further carried out at 80 ° C. for 2 hours, after which the suspension was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , filtered, washed with water and dried to obtain a weight average particle size of 7.0. μm toner particles were obtained. 0.8 parts of hydrophobic silica (TG820F) was externally added to the toner particles and mixed with a Henschel mixer to obtain toner AG having an average sphericity of 0.980.
(Measurement and evaluation method)
Average circularity: Using a flow particle analyzer FPIA-1000 (manufactured by Toa Medical Electronics), the average circularity of a particle group having a circle-equivalent diameter of 3 μm or more was determined.

Wax endothermic peak: An endothermic curve was determined using a differential thermal analyzer DSC-3200 (manufactured by MAC SCIENCE). The measurement sample (wax) is 10 mg, put in an aluminum pan, an empty aluminum pan is used as a reference, and the temperature is between 25 to 200 ° C. and the heating rate is 10 ° C./min. It was measured.
Fixability: An image test was performed with an electrophotographic copying machine [KM3530, Kyocera Mita Co., Ltd., using an amorphous silicon drum]. In the test, a black solid original of A4 size was copied and an unfixed image was created.

(A) Evaluation of offset resistance; passing the above-mentioned unfixed image through a fixing device modification machine of an electrophotographic copying machine [KM3530 manufactured by Kyocera Mita Co., Ltd.] to determine whether or not a toner offset phenomenon has occurred in the copied image. Judgment was made visually (5 samples).
(B) Measurement of fixing rate: In the above operation (a), the image density (A) of the image was measured when the fixing temperature was 130 ° C. On the other hand, the surface of the copied image was reciprocated five times by its own weight using a fixing property measuring device in which the bottom surface of a mild steel weight (diameter 50 mm, weight 400 g) was fixed with double-sided tape. (B) was measured. Here, a reflection densitometer (TC-6D, manufactured by Tokyo Denshoku) was used for measuring the image density.

Fixing rate = [Image density (B) / Image density (A)] × 100
(Low temperature) Set temperature 130 ℃
○: No offset, fixing rate of 98% or more
Δ: No offset, fixing rate less than 98%
×: Offset generation (high temperature) Set temperature 220 ° C
Y: No offset
Δ: Offset generated (when 2 or less)
×: Offset generation (when 3 or more)
Blocking resistance (storability): Using an electrophotographic printer [LS-9500DN Kyocera Mita Co., Ltd.] modified machine (roller peripheral speed: 370 mm / sec), after printing out 5000 sheets with a room temperature storage cartridge, The cartridge was replaced with a stored product (50 ° C., 8 hours), and image deterioration was confirmed. The difference between the image density before replacing the cart and the stored product and the image density after 3000 sheets were determined and evaluated according to the following scale.

○: Less than 0.1 Good blocking resistance (preservability).
Δ: 0.1-0.2 Blocking resistance (storability) is slightly inferior.
X: 0.2 or more Blocking resistance (storability) is inferior, which is not preferable for practical use.
Image density and fog: In an environment of high temperature and high humidity (35 ° C., 85%), the initial and 5000 were modified with an electrophotographic printer [LS-9500DN manufactured by Kyocera Mita Co., Ltd.] (roller peripheral speed: 370 mm / sec). The image density and fog after the sheet printout were measured. For the image density and fog, a reflection densitometer (TC-6D, manufactured by Tokyo Denshoku Co., Ltd.) was used to measure the density of the black solid portion of the printer image and the non-image portion.

○: Image density 1.2 or more
Δ: Image density of 1.1 to less than 1.2
×: Image density less than 1.1
○: fog Non-image area density less than 0.008
X: fog Non-image part density 0.008 or more Toner adhesion to photoconductor: 10000 sheets printed out with electrophotographic printer [LS-9500DN Kyocera Mita Co., Ltd.] remodeling machine (roller peripheral speed: 370 mm / sec) After that, the drum was visually observed to check for adhesion.

○: No toner component adhered
×: Toner component attached

In the column of “Examples and Reference Examples” in Table 2, numbers 1, 4, 7, 9, 11, 13, 14, 19, 23, 25, 27 and 29 are examples, and numbers 2, 3, 5 6, 8, 10, 12, 15-18, 10-22, 24, 26, 28 and 30-32 are reference examples.

  As shown in the results of Table 2, according to Examples 1 to 30, in high-speed fixing, all of the fixing property, blocking resistance (storability), image quality under high temperature and high humidity, and adhesion to the photosensitive drum are satisfied. Evaluation results to be obtained are obtained. In addition, Example 31 is slightly inferior in high temperature offset and Example 32 is slightly inferior in blocking resistance and adhesion, but is practical. On the other hand, as shown in the results of Table 3, Comparative Examples 1 to 16 have practical problems in any of the evaluation items.

  The magnetic toner of the present invention is excellent in preservability because it can fix at high speed from a low temperature region to a high temperature region and has anti-blocking property in image formation by an electrophotographic image forming apparatus.

Claims (3)

A toner used in an image forming apparatus including a developing device that develops and visualizes toner on an electrostatic latent image formed on an image carrier, and a fixing device including a pressure roller and a heating roller,
The toner is for high-speed fixing at a fixing roller peripheral speed of 300 to 450 mm / sec, contains at least a binder resin mainly composed of a polyester resin, magnetic powder, and wax, and has an average circularity of the toner particles. 0.95 to 0.96, and the wax is a two-component wax having an endothermic peak in differential thermal analysis in the range of (A) 70 to 85 ° C. and (B) 130 to 150 ° C. A magnetic toner comprising 100 parts by weight and 20 to 70 parts by weight of wax (B) . 2. The magnetic toner according to claim 1, wherein one of the wax components is polypropylene wax, and the polypropylene wax is contained in an amount of 1 to 3 parts by weight with respect to 100 parts by weight of the binder resin. Manufactures high-speed fixing toner used in an image forming apparatus including a developing device that develops and visualizes toner on an electrostatic latent image formed on an image carrier, and a fixing device that includes a pressure roller and a heating roller. In this case, a binder resin mainly composed of a polyester resin, a magnetic powder, and a two-component wax having endothermic peaks in a range of (A) 70 to 85 ° C. and (B) 130 to 150 ° C. in differential thermal analysis. Are melt-kneaded at a ratio of 100 parts by weight of wax (A) and 20-70 parts by weight of wax (B) , and the resulting melt-kneaded product is cooled and ground to obtain an average circularity of 0.95-0.96. A method for producing a magnetic toner, comprising obtaining toner particles.