JP4560462B2 - toner - Google Patents

Description

  The present invention relates to a toner used for developing an electrostatic image formed in an image forming method such as an electrophotographic method, an electrostatic recording method, a magnetic recording method, and a toner jet recording method.

  In recent years, printers and copiers have been shifting from analog to digital, and there is a strong demand for higher reproducibility of latent images and higher resolution, while at the same time improving print speed and reducing power consumption.

  For example, paying attention to the printer, the ratio of power consumption in the fixing process to the total power consumption is considerably large, and the power consumption increases as the fixing temperature increases. Further, when the fixing temperature becomes high, problems such as curling of the printout paper also occur, and there is a great demand for lowering the fixing temperature.

  Various methods and apparatuses have been developed for the fixing process. For example, there are a thermo-compression method using a heat roller and a surf fixing method in which heat energy is applied and fixed using a fixing film. The surf fixing method has the advantages that the power consumption of the film is remarkably reduced due to the small heat capacity of the film, and the waiting time can be shortened. However, on the other hand, since the toner is not easily crushed and the heat is not sufficiently transmitted because the fixing is performed under a light pressure, only one surface of the toner image is extremely melted and adhered to the fixing film. There is also a problem that an offset is likely to occur. This becomes more prominent as the printing speed increases.

  Conventionally, it has been known for a long time to contain a wax as a release agent in a toner in order to obtain a toner having excellent fixing properties. However, if the toner simply contains a wax having a low softening point, it adversely affects the fluidity, chargeability, durability, and storage stability of the toner.

  In order to solve such a problem, a polymerized toner containing a saturated polyester has been proposed (for example, see Patent Document 1). In the case of a polymerized toner produced in an aqueous medium, it is considered that a polar resin such as polyester is unevenly distributed on the surface. The toner obtained by this method has some problems in terms of fluidity, but lacks charging stability under high temperature and high humidity over a long period of time. This is presumably because the adhesiveness between the polyester resin and the binder resin was not sufficient, and the polyester resin as the surface layer could not completely protect the binder resin inside.

  For the purpose of enhancing the adhesion between the core and the shell, a toner in which a vinyl monomer is vinyl polymerized in a capsule shell containing a polymerization initiating azo group, or the capsule shell is a mixture of a vinyl polymer and a polyamide, and Toners and the like in which the components of the mixture are chemically bonded have been proposed (see, for example, Patent Documents 2 and 3). However, both of these methods perform polymerization at the interface between the core and the shell at the time of toner production, and do not strictly control the structure of the final capsule shell. As a result of studies by the present inventors, it has been found that the toner as described above has improved charging stability and durability, but the fixing performance is not at a satisfactory level. This is considered to be because the produced capsule shell is a random copolymer having a cross-linked structure, and the surface hardness has increased.

  On the other hand, a capsule toner for heat and pressure fixing having a hybrid resin obtained by performing a condensation polymerization reaction and an addition polymerization reaction in the same reaction vessel in parallel as a main component of the outer shell is disclosed (for example, Patent Document 4). However, as a result of investigations by the present inventors, it has been found that the surf fixing method cannot provide sufficient fixing performance due to recent high speed and low power consumption.

Japanese Patent Laid-Open No. 60-238846 Japanese Patent Laid-Open No. 5-61237 JP-A-5-142847 Japanese Patent No. 2984901

  An object of the present invention is to provide a toner that solves the above-mentioned problems of the prior art.

  That is, an object of the present invention is to provide a toner that exhibits good fixability and is excellent in low-temperature fixability even in the surf fixing method.

  It is another object of the present invention to provide a toner having excellent charge stability and high image density and low fog even when used for a long time in a high temperature and high humidity environment.

  Another object of the present invention is to provide a toner that is excellent in storage stability and durability, maintains high fluidity even during long-term use in a high-temperature and high-humidity environment, and does not cause fusing.

The present invention is a toner having toner particles containing at least a binder resin, a colorant and a wax ,
The toner particles are produced in an aqueous medium,
The toner particles have a core and a shell, and the shell of the toner particles contains a modified vinyl polymer modified with polyester,
The polyester modification amount of the modified vinyl polymer is less than 50% by mass,
The acid value of the modified vinyl polymer is 1 mgKOH / g or more and 10.2 mgKOH / g or less ,
The glass transition point of the modified vinyl polymer is 30 ° C. to 80 ° C.,
The modified vinyl polymer is Ri block copolymer der of polyester and vinyl polymer,
The toner relates to a toner comprising 5 to 50 parts by mass of the modified vinyl polymer based on 100 parts by mass of a binder resin .

  The toner of the present invention is excellent in low-temperature fixability and has a wide fixing temperature range even in the surf fixing system.

  Further, by using the toner of the present invention, it is possible to obtain an image with high image density and less fog even when used for a long time in a high temperature and high humidity environment.

  Further, the toner of the present invention is excellent in storage stability and durability, maintains high fluidity even during long-term use in a high temperature and high humidity environment, and can suppress the occurrence of fusion.

  As a result of intensive studies on the homogenization and stabilization of the charge amount, and the compatibility between low-temperature fixability and offset resistance, the present inventors have included a polyester-modified vinyl polymer having a specific structure. In addition to satisfying image characteristics such as developability and transferability, the inventors have found that the durability is improved and that the toner has a wide fixing temperature range, and the present invention has been achieved. That is, the polyester modification amount of the modified vinyl polymer is less than 50% by mass, the acid value is 1 mgKOH / g or more, and further having a block structure improves the compatibility with the binder resin and wax. It was possible to achieve compatibility between developability, storage stability and fixability.

  Furthermore, the toner of the present invention is particularly preferably a toner produced in an aqueous medium. In the aqueous medium, it is considered that the modified vinyl polymer is localized near the surface layer of the toner particles. At that time, since the modified vinyl polymer has a block structure, the polyester-modified portion having an acid value is easily phase-separated clearly on the outermost layer and the vinyl polymer portion on the inner side. As a result, a double shell surrounds the core mainly composed of the binder resin. At this time, since the vinyl polymer part is well-familiar with the binder resin, a large amount of wax for improving the low-temperature fixability and a binder resin containing it with a low glass transition point are firmly encapsulated. It is considered that both low-temperature fixability and blocking resistance can be achieved.

  The modified vinyl polymer contained in the toner of the present invention is a block copolymer of polyester and vinyl polymer, and has a polyester modification amount of less than 50% by mass. When the modified vinyl polymer is not a block copolymer but has a graft copolymer or a crosslinked structure, the polyester-modified part and the vinyl polymer part are difficult to separate. In particular, when the polyester modification amount is less than 50% by mass as in the present invention, the compatibility with the binder resin component is increased and the polyester component is hardly present on the toner surface. For this reason, both the chargeability and the fluidity are likely to be deteriorated, resulting in poor image quality. On the other hand, since the modified vinyl polymer of the present invention has a block structure, a double shell surrounds the core, and complete encapsulation is achieved. Furthermore, when the polyester modification amount is less than 50% by mass, that is, the vinyl polymer component is present by 50% by mass or more, not only the adhesion to the core is improved, but also the double shell structure becomes clearer and the storage stability is improved. It is considered that it has become possible to achieve complete functional separation between the polyester surface layer that enhances durability and the core that improves low-temperature fixability.

  The modified vinyl polymer contained in the toner of the present invention has an acid value of 1 mgKOH / g or more. By having an acid value of 1 mgKOH / g or more, the modified vinyl polymer can be localized on the toner surface in the production in an aqueous medium, the granulation property becomes good, and the storage property and durability are also improved. Becomes higher.

  The modified vinyl polymer contained in the toner of the present invention preferably has a weight average molecular weight of 3000 to 20000 as measured by GPC, and more preferably 3000 to 12000. When the weight average molecular weight is within this range, the low-temperature fixability is further improved. If the weight average molecular weight of the modified vinyl polymer is greater than 20000, the solubility deteriorates and the granulation property is adversely affected when the polymer is dissolved in a polymerizable monomer, suspended in an aqueous medium and polymerized. It is easy to prevent dispersion of the colorant. Furthermore, the interaction between the molecular chains becomes too strong, and the effect of low-temperature fixability is reduced in the surf fixing method. On the other hand, if the weight average molecular weight is less than 3000, the surface hardness decreases and the durability deteriorates. Moreover, storage stability will also fall.

  The glass transition point of the modified vinyl polymer contained in the toner of the present invention is preferably 30 to 80 ° C. If the glass transition point is less than 30 ° C., the storage stability of the toner tends to be poor, and if it exceeds 80 ° C., the fixability of the toner tends to be poor.

  In the present invention, a toner having a highly controlled double capsule structure can be obtained by independently designing the glass transition point of the polyester-modified portion and vinyl-based polymer portion of the modified vinyl polymer that is a block copolymer. Can be obtained. For example, when the polyester-modified part is produced in an aqueous medium, it is considered that the polyester-modified part is localized in the outermost layer of the toner particles. Therefore, the glass transition point is preferably 60 ° C. or higher from the viewpoint of durability and storage stability. . For the vinyl polymer part serving as the second shell, when the glass transition point of the core is very low or a large amount of wax is contained, the vinyl polymer part is added in order to increase the protective effect of the core. It is preferable to design at a temperature of ° C or higher. On the other hand, from the viewpoint of low-temperature fixability, for example, designing at 40 ° C. or lower is one of preferable modes. Even in this case, since the vinyl polymer part is chemically bonded to the polyester-modified part forming the outer shell, a part of the low Tg component is not released from the toner and the storage stability is not deteriorated. As described above, by arbitrarily controlling the double capsule structure, it is possible to achieve both a low-temperature fixing property and a storage stability at a high level, and a low-temperature fixing toner that can be used for various fixing device configurations. Obtainable.

  The effects described so far can be obtained for the first time by previously producing and adding a block copolymer in which a polyester unit and a vinyl polymer unit are chemically bonded. It is difficult to achieve by adding a mixture of a polyester and a vinyl polymer or a graft copolymer, or interfacial polymerization or seed polymerization at the time of toner production.

  The toner of the present invention preferably contains 5 to 50 parts by mass of the modified vinyl polymer with respect to 100 parts by mass of the binder resin. When the content of the modified vinyl polymer is less than 5 parts by mass, it is insufficient for forming a double shell layer on the toner surface layer, and the effect of the present invention is reduced. In addition, sufficient fluidity cannot be obtained and the image quality tends to be inferior. On the other hand, when the content of the modified vinyl polymer is larger than 50 parts by mass, a large amount of fine powder containing a large amount of the modified vinyl polymer component is easily generated in the suspension, and the particle size distribution is widened.

  The following are mentioned as a polymerizable monomer which comprises the vinyl polymer which is a main component of the modified vinyl polymer used for this invention.

  For example, styrene; α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, p Styrene derivatives such as -n-hexyl styrene, pn-octyl, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene; methyl acrylate, Ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n- Acrylic polymerizable monomers such as nonyl acrylate, cyclohexyl acrylate, benzyl acrylate, dimethyl phosphate ethyl acrylate, diethyl phosphate ethyl acrylate, dibutyl phosphate ethyl acrylate, 2-benzoyloxyethyl acrylate; methyl methacrylate, ethyl methacrylate, n -Propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate, diethyl Phosphate ethyl methacrylate, dibutyl phosphate Methacrylic polymerizable monomers such as methyl methacrylate; methylene aliphatic monocarboxylic acid esters; vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, vinyl benzoate, vinyl formate; vinyl methyl ether; And vinyl ethers such as vinyl ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropyl ketone.

  These monomers can be used alone or in combination. Among the monomers described above, styrene or a styrene derivative is preferably used alone or mixed with another monomer from the viewpoint of the affinity with the binder resin.

  The typical composition of the polyester which is a modified part of the modified vinyl polymer used in the present invention is as follows.

  Among the monomers constituting the polyester resin, polyhydric alcohols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, diethylene glycol, and dipropylene glycol. , Triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2,2,4-trimethylpentane-1,3-diol, hydrogenated bisphenol A, or the following formula (I) And diols represented by the following formula (II). These polyhydric alcohols may be used alone or in a mixed state. However, it is not limited to these, and other trivalent or higher alcohol components can be used as the crosslinking component.

（式中、Ｒはエチレン又はプロピレン基であり、ｘ及びｙはそれぞれ１以上の整数であり、且つｘ＋ｙの平均値は２〜１０である。）

(In the formula, R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10.)

  Among the monomers constituting the polyester resin, the polyvalent carboxylic acid component includes naphthalene dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, succinic acid, adipic acid And dicarboxylic acids such as sebacic acid and azelaic acid; dicarboxylic acid anhydrides such as phthalic anhydride and maleic anhydride; and lower alkyl esters of dicarboxylic acids such as dimethyl terephthalate, dimethyl maleate and dimethyl adipate. . In particular, the main component is preferably a lower alkyl ester of a dicarboxylic acid such as dimethyl terephthalate, dimethyl maleate, dimethyl adipate or a derivative thereof.

  The polyester resin may be crosslinked by using the following trivalent or higher acid component. Examples of the crosslinking component include trimellitic acid, tri n-ethyl 1,2,4-tricarboxylate, tri n-butyl 1,2,4-tricarboxylate, tri n-hexyl 1,2,4-tricarboxylate, Triisobutyl 2,4-benzenetricarboxylate, tri-n-octyl 1,2,4-benzenetricarboxylate, tri-2-ethylhexyl 1,2,4-benzenetricarboxylate and lower alkyl esters of tricarboxylic acid can be used. However, the present invention is not limited thereto, and other trivalent or higher acid components or trivalent or higher carboxylic acid lower alkyl esters can be used as the crosslinking component.

  Moreover, you may use a monovalent carboxylic acid component and a monovalent alcohol component to such an extent that the properties of the polyester resin that can be used in the modified vinyl polymer of the present invention are not impaired. For example, benzoic acid, naphthalenecarboxylic acid, salicylic acid, 4-methylbenzoic acid, 3-methylbenzoic acid, phenoxyacetic acid, biphenylcarboxylic acid, acetic acid, propionic acid, butyric acid, octanoic acid, decanoic acid, dodecanoic acid, stearic acid, etc. Monocarboxylic acid, and one or more kinds of 1 such as n-butanol, isobutanol, sec-butanol, n-hexanol, n-octanol, lauryl alcohol, 2-ethylhexanol, decanol, cyclohexanol, benzyl alcohol, dodecyl alcohol, etc. Functional monomers and the like can be added.

  The polyester resin that can be used in the modified vinyl polymer of the present invention can be produced by an ordinary polyester synthesis method. For example, after the polyvalent carboxylic acid component and the polyhydric alcohol component are esterified or transesterified, the low-boiling polyhydric alcohol component is reduced under reduced pressure or nitrogen gas is introduced, and the reaction is carried out according to a conventional method. A polyester resin is obtained by a condensation reaction. In the esterification or transesterification reaction, an ordinary esterification catalyst or transesterification catalyst such as sulfuric acid, titanium butoxide, dibutyltin oxide, manganese acetate, and magnesium acetate can be used as necessary. Regarding polymerization, known polymerization catalysts such as titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, germanium oxide and the like can be used.

  Further, the polymerization temperature and the amount of catalyst are not particularly limited, and may be arbitrarily selected as necessary.

  The modified vinyl polymer used in the present invention can be produced by various methods. For example, it is preferable to produce the modified vinyl polymer in the following manner from the viewpoint of the simplicity of reaction and cost. First, after production of the polyester unit, a monomer capable of reacting with both the vinyl polymer component and the polyester resin component is reacted. Then, it can manufacture by carrying out addition polymerization of the polyester which has a polymeric group in the chain | strand terminal to produce | generate, and a vinyl type polymerizable monomer.

  Monomers that can react with both the vinyl polymer component and the polyester resin component include unsaturated dicarboxylic acids such as phthalic acid, maleic acid, citraconic acid, and itaconic acid, or anhydrides thereof, acrylic acid, methacrylic acid, and acrylic acid esters. Methacrylic acid esters, acrylic acid esters having an isocyanate group, and methacrylic acid esters having an isocyanate group. Among these, methacrylic acid esters having an isocyanate group are particularly suitable.

  The toner of the present invention preferably has a glass transition point of 10 to 60 ° C. When the glass transition point is less than 10 ° C., the strength of the toner particles is lowered and the transferability and developability are liable to deteriorate during the durability test. In addition, storage stability deteriorates. On the other hand, if the glass transition point exceeds 60 ° C., the low-temperature fixability is deteriorated.

  The toner of the present invention preferably contains magnetic iron oxide as a colorant. Jumping development method using magnetic toner (insulating magnetic toner is thinly applied on a developer carrying member, triboelectrically charged, and then brought into close contact and contact with an electrostatic latent image under the action of a magnetic field. The method of developing without facing each other) can obtain a high-definition image with less fog.

  However, the developing method using magnetic toner has unstable factors related to the magnetic toner to be used. This is because a considerable amount of fine magnetic powder is mixed and dispersed in the toner, and a part of the magnetic material is exposed on the surface of the toner particles, so that the fluidity and triboelectric chargeability of the toner are lowered. That's it. For this reason, in long-term use, the developer is deteriorated, such as a decrease in image density due to separation of the magnetic material due to rubbing between the toners or the regulating member, and generation of shading unevenness called sleeve ghost.

  In order to solve these problems, it is important to modify the surface characteristics of the magnetic powder. Therefore, it is preferable that the magnetic powder used in the magnetic toner of the present invention is uniformly hydrophobized with a coupling agent.

  There are two methods of treating the surface of the magnetic powder with a coupling agent: dry treatment and wet treatment.

  When wet processing is performed, it is preferable to perform surface treatment while hydrolyzing the coupling agent in an aqueous medium in a state where iron oxide is dispersed to have a primary particle size, and after washing the magnetic material produced in an aqueous solution It is more preferable to perform the hydrophobic treatment without drying.

Examples of the coupling agent that can be used for the hydrophobizing treatment of iron oxide include a silane coupling agent and a titanium coupling agent. More preferably used is a silane coupling agent having the general formula RmSiYn
[Wherein, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents a hydrocarbon group such as an alkyl group, a vinyl group, a glycidoxy group or a methacryl group, and n represents an integer of 1 to 3] Show. ]
It is shown by. For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethyl Mention may be made of methoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane and n-octadecyltrimethoxysilane.

In particular, the formula C _p H _{2p + 1} —Si— (OC _q H _{2q + 1} ) ₃
[Wherein p represents an integer of 2 to 20, and q represents an integer of 1 to 3]
It is preferable to hydrophobize iron oxide using an alkyltrialkoxysilane coupling agent represented by

  When p in the above formula is smaller than 2, the hydrophobic treatment is easy, but it is difficult to impart sufficient hydrophobicity. When p is larger than 20, the hydrophobicity is sufficient, but iron oxide The coalescence of the particles increases and it becomes difficult to sufficiently disperse the iron oxide particles in the toner.

  On the other hand, when q is larger than 3, the reactivity of the silane coupling agent is lowered and the hydrophobicity is not sufficiently performed.

  In particular, p in the formula represents an integer of 2 to 20 (more preferably an integer of 3 to 15), and q represents an integer of 1 to 3 (more preferably an integer of 1 or 2). A coupling agent should be used.

  The treatment amount is 0.05 to 20 parts by mass, preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of iron oxide.

  In order to treat the surface of the magnetic powder with a coupling agent in an aqueous medium, a method of stirring an appropriate amount of the magnetic powder and the coupling agent in the aqueous medium can be mentioned.

  An aqueous medium is a medium containing water as a main component. Specific examples of the aqueous medium include water itself, water added with a small amount of a surfactant, water added with a pH adjusting agent, and water added with an organic solvent. As the surfactant, a nonionic surfactant such as polyvinyl alcohol is preferable. The surfactant is preferably added in an amount of 0.1 to 5% by mass with respect to water. Examples of the pH adjuster include inorganic acids such as hydrochloric acid.

  Stirring is sufficiently performed, for example, with a mixer having a stirring blade (specifically, a high shear force mixing device such as an attritor or a TK homomixer) so that the iron oxide fine particles become primary particles in the aqueous medium. Is good.

  The iron oxide used in the toner of the present invention is preferably used in an amount of 10 to 200 parts by weight, more preferably 20 to 180 parts by weight, based on 100 parts by weight of the binder resin. When the blending amount of iron oxide is less than 10 parts by mass, the coloring power of the developer is poor, and it is difficult to suppress fogging. On the other hand, when it exceeds 200 parts by mass, the coercive force due to the magnetic force on the developer carrying member is increased and developability is increased. Not only is it difficult to uniformly disperse iron oxide in individual toner particles, but also the fixability is reduced.

  Next, a method for producing toner according to the present invention will be described.

  The toner of the present invention can be produced by a pulverization method, but the pulverization method requires a multi-step process in order to obtain the double capsule structure as described above, from the viewpoint of yield and cost. It is disadvantageous.

  On the other hand, in a toner production method (hereinafter referred to as a polymerization method) obtained by directly polymerizing a monomer system in an aqueous medium, it is locally between polar and nonpolar components from the viewpoint of affinity with the aqueous medium. Since presence / separation is likely to occur, a double capsule structure can be obtained in one step, which is preferable.

  The following are mentioned as a polymerizable monomer which comprises the polymerizable monomer type | system | group used for this invention.

  Examples of the polymerizable monomer include styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, and p-ethylstyrene; methyl acrylate, ethyl acrylate, Acrylic esters such as n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate Class: Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenolic methacrylate , Dimethylaminoethyl methacrylate, such as methacrylic acid esters of diethylaminoethyl methacrylate; acrylonitrile, methacrylonitrile, acrylamide.

  These monomers can be used alone or in combination. Among the above-mentioned monomers, styrene or a styrene derivative is preferably used alone or mixed with other monomers from the viewpoint of the developing characteristics and durability of the toner.

  The toner of the present invention preferably contains 1 to 50% by weight of a release agent with respect to the binder resin. If the content of the release agent is less than 1% by mass, the effect of suppressing low temperature offset is small, and if it exceeds 50% by mass, the long-term storage stability is lowered and the dispersibility of other toner materials is deteriorated. It leads to deterioration of fluidity and image characteristics.

  A known wax can be used as a release agent that can be used in the toner of the present invention. For example, paraffin wax, microcrystalline wax, petroleum wax such as petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon wax and derivatives thereof by Fischer-Tropsch method, polyolefin wax and derivatives thereof represented by polyethylene, carnauba wax Natural waxes such as candelilla wax and derivatives thereof. Derivatives here include oxides, block copolymers with vinyl monomers, and graft modified products. Furthermore, higher aliphatic alcohols, higher fatty acids or compounds thereof, acid amide waxes, ester waxes, ketones, hydrogenated castor oil and derivatives thereof, plant-based waxes, and animal waxes can also be used.

  Among these release agent components, those having an endothermic peak of 40 to 110 ° C. by differential thermal analysis, that is, the maximum endothermic peak in the region of 40 to 110 ° C. at the time of temperature rise in the DSC curve measured by a differential scanning calorimeter. What has is preferable, and what has in the area | region of 45-90 degreeC is further more preferable. By having the maximum endothermic peak in the above temperature range, the mold releasability is effectively expressed while greatly contributing to low-temperature fixing.

  The toner of the present invention may contain a charge control agent in order to stabilize the charge characteristics. As the charge control agent, known ones can be used, but a charge control agent that has a high charging speed and can stably maintain a constant charge amount is particularly preferable.

  Further, when the toner is produced by a direct polymerization method, a charge control agent having a low polymerization inhibitory property and substantially free from a solubilized product in an aqueous dispersion medium is particularly preferable. Specific compounds include, as negative charge control agents, metal compounds of aromatic carboxylic acids such as salicylic acid, alkylsalicylic acid, dialkylsalicylic acid, naphthoic acid, dicarboxylic acid, metal salts or metal complexes of azo dyes or azo pigments, sulfones Examples thereof include a polymer compound having an acid or carboxylic acid group in the side chain, a boron compound, a urea compound, a silicon compound, and a calixarene. 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. These charge control agents are preferably used in an amount of 0.5 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer. However, the developer involved in the image forming method of the present invention does not require the addition of a charge control agent, and the toner in the toner is positively utilized by frictional charging of the developer with the layer pressure regulating member or the developer carrier. It is not always necessary to include a charge control agent.

The iron oxide used as the magnetic material in the toner of the present invention may contain elements such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon, and is mainly composed of iron trioxide and γ-iron oxide. These are used as components, and these may be used alone or in combination of two or more. These iron oxides preferably have a BET specific surface area by a nitrogen adsorption method of ² to 30 m ² / g, particularly 3 to 28 m ² / g, and a Mohs hardness of 5 to 7.

  The shape of iron oxide includes octahedrons, hexahedrons, spheres, needles, scales, etc., but those with low anisotropy such as octahedrons, hexahedrons, spheres, and irregular shapes increase the image density. Preferred above. Such a shape can be confirmed by SEM or the like. As the particle size of iron oxide, the volume average particle size is 0.1 to 0.3 μm and 0.03 to 0.1 μm in the measurement of particle size targeting particles having a particle size of 0.03 μm or more. The number of particles is preferably 40% by number or less.

  When an image is obtained from a magnetic toner using iron oxide having an average particle size of less than 0.1 μm, the color of the image shifts to red, and the blackness of the image is insufficient, or the halftone image is more reddish. Generally, it is not preferable, such as a strong tendency to feel strongly. Further, since the surface area of iron oxide is increased, dispersibility is lowered, energy required for production is increased, and it is not efficient. Further, the effect of iron oxide as a colorant is weakened, and the image density may be insufficient, which is not preferable.

  On the other hand, if the average particle size of iron oxide exceeds 0.3 μm, the mass per particle increases, so the probability of exposure to the toner surface increases due to the difference in specific gravity with the binder during production, or the wear of the production equipment This is not preferable because the possibility that it becomes remarkable will increase or the sedimentation stability of the dispersion will decrease.

  In addition, when the number of particles of 0.1 μm or less of the iron oxide in the toner exceeds 40% by number, the surface area of the iron oxide is increased, the dispersibility is lowered, and agglomerates are easily formed in the toner. In order to increase the possibility of impairing the chargeability or reducing the coloring power, the number is preferably 40% by number or less. Furthermore, when it is 30% by number or less, the tendency becomes smaller, which is more preferable.

  It should be noted that iron oxide of less than 0.03 μm has a low probability of appearing on the surface of the toner particles because the stress applied during toner production is small due to the small particle diameter. Furthermore, even if it is exposed to the particle surface, it hardly acts as a leak site and is not substantially a problem. Therefore, in the present invention, attention is paid to particles of 0.03 to 0.1 μm, and the number% is defined.

  Further, if the number of particles of 0.3 μm or more in iron oxide exceeds 10% by number, the coloring power tends to decrease and the image density tends to decrease. It is not preferable that the toner particles exist in the vicinity of the surface of the toner particles and that a uniform number is included in each toner particle. More preferably, it is 5% or less.

  In the present invention, it is preferable to set iron oxide production conditions so as to satisfy the above-mentioned condition of particle size distribution, or to use one that has been previously adjusted for particle size distribution such as pulverization and classification. As the classification method, for example, a method using sedimentation separation such as centrifugal separation or thickener, or a wet classification device using a cyclone is suitable.

  The volume average particle size and particle size distribution of iron oxide are determined by the following measurement method.

  With the particles sufficiently dispersed, the projection area of each of the 100 iron oxide particles in the field of view was measured with a transmission electron microscope (TEM) at a magnification of 30,000 times, and each of the measured particles was measured. The equivalent diameter of a circle equal to the projected area was determined as each particle diameter. Furthermore, based on the result, the volume average particle diameter was calculated, and the number% of particles having a size of 0.03 to 0.1 μm and particles having a size of 0.3 μm or more was calculated. The particle size was measured for particles having a particle size of 0.03 μm or more. It is also possible to measure the particle size with an image analyzer.

  When determining the volume average particle size and particle size distribution of iron oxide in the toner particles, the following measurement method is used.

  After sufficiently dispersing the toner particles to be observed in the epoxy resin, the cured product obtained by curing in an atmosphere at a temperature of 40 ° C. for 2 days was used as a flaky sample by a microtome, and a transmission electron microscope (TEM). , The projected area of each of the 100 iron oxide particles in the field of view is measured with a photograph with a magnification of 10,000 to 40,000 times, and the equivalent diameter of a circle equal to the measured projected area of each particle is The particle diameter was obtained. Further, based on the results, the number% of particles having a size of 0.03 to 0.1 μm and particles having a size of 0.3 μm or more was calculated. It is also possible to measure the particle size with an image analyzer.

  Furthermore, other colorants may be used in combination with iron oxide. Examples of coloring materials that can be used in combination include magnetic or nonmagnetic inorganic compounds, and known dyes and pigments. Specifically, for example, ferromagnetic metal particles such as cobalt and nickel, or alloys obtained by adding chromium, manganese, copper, zinc, aluminum, rare earth elements to these, hematite, titanium black, nigrosine dye / pigment, carbon black, Examples include phthalocyanine. These may also be used after treating the surface.

  The polymerization initiator used in the present invention has a half-life of 0.5 to 30 hours during the polymerization reaction. When the polymerization reaction is carried out with an addition amount of 0.5 to 20% by mass of the polymerizable monomer, the molecular weight A polymer having a maximum between 10,000 and 100,000 can be obtained, and the toner can be provided with desirable strength and suitable melting characteristics. Examples of polymerization initiators include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile ), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo or diazo polymerization initiators such as azobisisobutyronitrile; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate , Peroxide polymerization initiators such as cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide.

  In the present invention, a crosslinking agent may be added, and a preferable addition amount is 0.001 to 15% by mass of the polymerizable monomer.

  In the production of toner by suspension polymerization, generally, the above-described toner composition, that is, a polymerizable monomer, contains iron oxide, a colorant, a release agent, a plasticizer, a binder, a charge control agent, a crosslinking agent, and the like. Components necessary for the toner and other additives such as an organic solvent and a dispersant added to lower the viscosity of the polymer produced by the polymerization reaction, as appropriate, homogenizer, ball mill, colloid mill, ultrasonic disperser, etc. The monomer system uniformly dissolved or dispersed by the dispersing machine is suspended in an aqueous medium containing a dispersion stabilizer. At this time, the particle size of the obtained toner particles becomes sharper by using a high-speed disperser such as a high-speed stirrer or an ultrasonic disperser to obtain a desired toner particle size at a stretch. The polymerization initiator may be added at the same time when other additives are added to the polymerizable monomer, or may be mixed immediately before being suspended in the aqueous medium. Also, a polymerization initiator dissolved in a polymerizable monomer or solvent can be added immediately after granulation and before starting the polymerization reaction.

  After granulation, stirring may be performed using a normal stirrer to such an extent that the particle state is maintained and particle floating and sedimentation are prevented. In order to appropriately segregate near the surface using the polar compound of the present invention, the pH in the aqueous medium before adding the monomer system is important. The pH is preferably 4 to 10.5. If the pH is less than 4, the effect of the polar compound almost disappears, so that a large amount of polar substance needs to be added, and the effect of lowering the charge amount, broadening of the particle size distribution, and the like occurs. On the other hand, if the pH exceeds 10.5, the addition of a polar compound promotes the exposure of some of the magnetic materials, making it difficult to maintain the magnetic structure of the present invention.

  In the suspension polymerization method of the present invention, known surfactants and organic / inorganic dispersants can be used as dispersion stabilizers. In particular, inorganic dispersants are less likely to produce harmful ultrafine powders, and their steric hindrance prevents dispersion stability. Therefore, even if the reaction temperature is changed, the stability is not easily lost, the cleaning is easy, and the toner is not adversely affected. Examples of such inorganic dispersants include polyvalent metal phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate and zinc phosphate; carbonates such as calcium carbonate and magnesium carbonate; calcium metasuccinate, calcium sulfate and barium sulfate. Inorganic salts; inorganic oxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, silica, bentonite and alumina can be mentioned.

  These inorganic dispersants are preferably used alone or in combination of two or more kinds in an amount of 0.2 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer. When aiming at a more finely divided toner having an average particle diameter of 5 μm or less, 0.001 to 0.1 parts by mass of a surfactant may be used in combination.

  Examples of the surfactant include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, sodium stearate, and potassium stearate.

  When these inorganic dispersants are used, they may be used as they are, but in order to obtain finer particles, the inorganic dispersant particles can be generated in an aqueous medium. For example, in the case of calcium phosphate, a sodium phosphate aqueous solution and a calcium chloride aqueous solution can be mixed with high-speed stirring to produce water-insoluble calcium phosphate, which enables more uniform and fine dispersion. At the same time, a water-soluble sodium chloride salt is produced as a by-product. However, if a water-soluble salt is present in the aqueous medium, dissolution of the polymerizable monomer in water is suppressed, and an ultrafine toner based on emulsion polymerization is produced. Since it becomes difficult to generate | occur | produce, it is more convenient. Since it becomes an obstacle when removing the remaining polymerizable monomer at the end of the polymerization reaction, it is better to replace the aqueous medium or desalinate with an ion exchange resin. The inorganic dispersant can be almost completely removed by dissolving with an acid or alkali after completion of the polymerization.

  In the polymerization step, the polymerization is performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. When the polymerization is carried out in this temperature range, the release agent and wax to be sealed inside are precipitated by phase separation, and the encapsulation is more complete. In order to consume the remaining polymerizable monomer, the reaction temperature can be increased to 90 to 150 ° C. at the end of the polymerization reaction.

  The toner of the present invention is preferably mixed with an inorganic fine powder or a hydrophobic inorganic fine powder as a fluidity improver. For example, titanium oxide fine powder, silica fine powder, and alumina fine powder are preferably added and used, and silica fine powder is particularly preferred.

Inorganic fine powder used in the developer, specific surface area by nitrogen adsorption measured by BET method of more than 30 m ² / g, it is possible in particular in the range of 50 to 400 m ² / g give good results preferable.

  If necessary, an external additive other than the fluidity improver may be added to the toner in the present invention.

For example, for the purpose of improving cleaning properties, the primary particle diameter exceeds 30 nm (preferably the specific surface area is less than 50 m ² / g), more preferably the primary particle diameter is 50 nm or more (preferably the specific surface area is 30 m ^2). It is also one of preferable modes to add inorganic fine particles or organic fine particles that are nearly spherical at a rate of less than / g). For example, spherical silica particles, spherical polymethylsilsesquioxane particles, and spherical resin particles are preferably used.

  Still other additives such as lubricant powders such as polyfluorinated ethylene powder, zinc stearate powder, polyvinylidene fluoride powder; or abrasives such as cerium oxide powder, silicon carbide powder, strontium titanate powder; anti-caking agent; Conductivity imparting agents such as carbon black powder, zinc oxide powder and tin oxide powder; organic fine particles having opposite polarity and inorganic fine particles can be added in a small amount as a developability improver. These additives can also be used after hydrophobizing the surface.

  As described above, the external additive may be used in an amount of 0.1 to 5 parts by mass (preferably 0.1 to 3 parts by mass) with respect to 100 parts by mass of the toner.

  When the toner of the present invention is produced by a pulverization method, a known method can be used. For example, after sufficiently mixing other additives such as a binder resin necessary as a toner, the modified vinyl polymer of the present invention, a colorant, a release agent, and a charge control agent in a mixer such as a Henschel mixer and a ball mill, It is melt-kneaded using a heat kneader such as a heating roll, a kneader, or an extruder, and uniformly dispersed. Thereafter, cooling solidification, pulverization, classification, and surface treatment as necessary are performed to obtain toner particles. The pulverization step can be performed using a known pulverizer such as a mechanical impact type or a jet type. After the pulverization step, further heat may be applied for pulverization or auxiliary mechanical impact may be applied. Further, a hot water bath method in which finely pulverized (classified as necessary) particles are dispersed in hot water, a method of passing in a hot air stream, or the like may be used.

  Furthermore, the toner of the present invention is a method for obtaining a spherical toner by atomizing a molten mixture into air using a disk or a multi-fluid nozzle described in JP-B-56-13945, etc. Represented by a dispersion polymerization method in which a toner is directly produced using an aqueous organic solvent in which the polymer obtained in 1 is insoluble, or a soap-free polymerization method in which a toner is produced by direct polymerization in the presence of a water-soluble polar polymerization initiator. The toner can also be produced by a method of producing toner using an emulsion polymerization method.

  An example of an image forming apparatus that can suitably use the toner of the present invention will be specifically described with reference to the drawings.

  In the image forming apparatus of FIG. 1, reference numeral 100 denotes a photosensitive drum, and a primary charging roller 117, a developing device 140, a transfer charging roller 114, a cleaner 116, a register roller 124, and the like are provided around the photosensitive drum. The photoreceptor 100 is charged to, for example, −700 V by the primary charging roller 117 (applied voltages are AC voltage −2.0 kVpp, DC voltage −700 Vdc). Then, exposure is performed by irradiating the photosensitive member 100 with a laser beam 123 by the laser generator 121. The electrostatic latent image on the photoconductor 100 is developed with a one-component magnetic developer by the developing device 140 and transferred onto the transfer material by the transfer roller 114 in contact with the photoconductor via the transfer material. The transfer material on which the toner image is placed is conveyed to the fixing device 126 by the conveying belt 125 or the like and fixed on the transfer material. In addition, toner remaining on a part of the photoconductor is cleaned by the cleaning unit 116. As shown in FIG. 2, the developing device 140 is provided with a cylindrical toner carrier 102 (hereinafter referred to as a developing sleeve) made of a nonmagnetic metal such as aluminum or stainless steel in the vicinity of the photosensitive member 100. The gap between 100 and the developing sleeve 102 is maintained at about 300 μm by a sleeve / photoreceptor gap holding member (not shown). A magnet roller 104 is fixed and arranged concentrically with the developing sleeve 102 in the developing sleeve. However, the developing sleeve 102 is rotatable. The magnet roller 104 is provided with a plurality of magnetic poles as shown in the figure, and S1 influences development, N1 regulates the amount of toner coating, S2 takes in / conveys toner, and N2 affects toner blowout prevention. The toner is applied to the developing sleeve 102 by the toner application roller 141, and is adhered and conveyed. An elastic blade 103 is provided as a member for regulating the amount of toner conveyed, and the amount of toner conveyed to the development area is controlled by the contact pressure of the elastic blade 103 against the developing sleeve 102. In the development region, a DC and AC development bias is applied between the photoconductor 100 and the development sleeve 102, and the developer on the development sleeve flies onto the photoconductor 100 in accordance with the electrostatic latent image to become a visible image. .

  The method for measuring various physical property data in the present invention is described in detail below.

(Measurement method of acid value)
The acid value is determined as follows. Basic operation conforms to JIS-K0070.

Test by:
(1) Reagent (a) Solvent ethyl ether-ethyl alcohol mixed solution (1 + 1 or 2 + 1) or benzene-ethyl alcohol mixed solution (1 + 1 or 2 + 1), these solutions were subjected to N / 10 hydroxylation using phenolphthalein as an indicator immediately before use. Neutralize with potassium ethyl alcohol solution.
(B) Phenolphthalein solution 1 g of phenolphthalein is dissolved in 100 ml of ethyl alcohol (95 v / v%).
(C) N / 10 potassium hydroxide-ethyl alcohol solution Dissolve 7.0 g of potassium hydroxide in as little water as possible, add ethyl alcohol (95 v / v%) to 1 liter, leave it for 2 to 3 days, and filter. The standardization is performed according to JIS K 8006 (basic matters concerning titration during the reagent content test).
(2) Operation Weigh correctly 1 to 20 g of sample, add 100 ml of solvent and a few drops of phenolphthalein solution as an indicator, and shake well until the sample is completely dissolved. In the case of a solid sample, dissolve it by heating on a water bath. After cooling, this is titrated with an N / 10 potassium hydroxide ethyl alcohol solution, and the end point of neutralization is defined as the time when the indicator is slightly red for 30 seconds.
3) Calculation formula The acid value is calculated by the following formula.

ここにＡ：酸価
Ｂ：Ｎ／１０水酸化カリウムエチルアルコール溶液の使用量（ｍｌ）
ｆ：Ｎ／１０水酸化カリウムエチルアルコール溶液のファクター
Ｓ：試料（ｇ）

Where A: acid value B: N / 10 amount of potassium hydroxide ethyl alcohol solution used (ml)
f: Factor of N / 10 potassium hydroxide ethyl alcohol solution S: Sample (g)

(GPC measurement)
The molecular weight specified in the present invention can be measured under the following measurement conditions using a gel permeation chromatography (GPC) measuring device (HLC-8120GPC manufactured by Tosoh Corporation).

Measurement conditions / column (made by Showa Denko KK): Shodex GPC KF-801, Shodex GPC KF-802, Shodex GPC KF-803, Shodex GPC KF-804, Shodex GPC KF-805, Shodex GPC KF-806, SPC KF-807 (8.0mmφ × 30cm) 7 stations, temperature: 40 ° C
・ Flow rate: 0.6ml / min
・ Detector: RI
・ Sample concentration: 10 μl of 0.1% sample

  The sample is prepared by placing the sample to be measured in tetrahydrofuran (THF) and allowing it to stand for 6 hours, and then shake it sufficiently (until the samples are united together) and leave it for 1 day or more. And let what passed the sample processing filter (pore size 0.45 micrometer) be a sample for GPC measurement. The calibration curve uses a molecular weight calibration curve created with a monodisperse polystyrene standard sample.

(DSC measurement)
It measures according to ASTM D3418-82 using a differential thermal analysis measuring device (DSC measuring device; DSC-7 (manufactured by Perkin Elmer)).

  The sample to be measured is precisely weighed 5 to 20 mg, preferably 10 mg. This is put in an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at a temperature rise rate of 10 ° C./min at room temperature and normal humidity within a measurement temperature range of 30 to 200 ° C.

(Degree of aggregation)
The degree of aggregation is used as one means for measuring the flow characteristics of a sample (toner having an external additive, classified product). The larger the value of the degree of aggregation, the worse the fluidity of the sample.

As a measuring device, a powder tester (manufactured by Hosokawa Micron Corporation) having a digital vibrometer (Digivibro Model 1332) is used. As a measuring method, 200 mesh, 100 mesh, and 60 mesh sieves are placed on the shaking table in the order of narrow mesh opening, that is, the 200 mesh, 100 mesh, and 60 mesh sieves are stacked so that the 60 mesh sieve comes to the top. To do. 5 g of accurately weighed sample is added to the set 60 mesh sieve so that the input voltage to the shaking table is 21.7 V, the displacement value of the digital shaking meter is 0.130, and the shaking table at that time Is adjusted to fall within the range of 60 to 90 μm (rheostat scale about 2.5), and vibration is applied for about 15 seconds. Thereafter, the weight of the sample remaining on each sieve is measured, and the degree of aggregation is obtained based on the following formula.
Aggregation degree (%) = 20A + 12B + 4C
(In the formula, A, B, and C are the masses (g) of the sample remaining on the 60 mesh, 100 mesh, and 200 mesh sieves, respectively)

  Hereinafter, the present invention will be specifically described with reference to production examples and examples, but this does not limit the present invention in any way. In addition, all the parts in the following mixing | blending are a mass part.

<Production of modified vinyl polymer 1>
Terephthalic acid 12.0mol
Propylene oxide modified bisphenol A 10.0 mol
The above monomer is charged into an autoclave together with an esterification catalyst, and a polycondensation reaction is carried out at 200 ° C. for 10 hours according to the information while reducing the pressure in a nitrogen atmosphere with a decompression device, a water separation device, a nitrogen gas introduction device, a temperature measurement device and a sales expansion device And polyester was obtained.

Next, 40 parts of the above polyester was added to 105 parts of xylene and heated to 75 ° C. with stirring in a nitrogen atmosphere. continue,
Isocyanate ethyl methacrylate (Karenz MOI) 5 parts After adding 0.0005 part of dibutyltin laurate, it was heated to 141 ° C. over about 30 minutes. there,
Styrene 50 parts butyl acrylate 10 parts tert-butyl peroxybenzoate 3 parts The above monomer and polymerization initiator mixed in advance were added dropwise over 2 hours. The radical polymerization reaction was completed by holding at that temperature for another 3 hours. Further, the pressure was reduced while heating to remove the solvent, whereby a polyester-modified vinyl polymer 1 was obtained. The physical properties are shown in Table 1.

<Production of modified vinyl polymers 2-6>
In the production of the modified vinyl polymer 1, a modification was made in the same manner as in the production of the modified vinyl polymer 1 except that the composition shown in Table 1 was changed and the amount of initiator, reaction temperature, reaction time, etc. were appropriately adjusted. Vinyl polymers 2 to 6 were obtained. The physical properties are shown in Table 1.

<Production of modified vinyl polymer 7>
Styrene 50 parts Butyl acrylate 10 parts Acrylic acid 5 parts In the above monomer and both reactive compounds, 3 parts of dicumyl peroxide as a polymerization initiator were dissolved and placed in a dropping funnel. 28 parts of propylene oxide-modified bisphenol A, 10.5 parts of terephthalic acid, and 1.5 parts of trimellitic anhydride (TMA) are placed in a glass 5-liter four-necked flask, thermometer, stainless steel stirring rod, flow-down type A condenser and a nitrogen introduction tube were attached, and the vinyl resin monomer and the polymerization initiator were added dropwise over 4 hours from the previous dropping funnel while stirring in a mantle heater under a nitrogen atmosphere at a temperature of 135 ° C. Aging was carried out for 5 hours while maintaining at 135 ° C, and the temperature was raised to 220 ° C and reacted for 10 hours to obtain a modified vinyl polymer 7 graft-modified with polyester. The physical properties are shown in Table 1.

<Manufacture of hydrophobic magnetic iron oxide>
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. While maintaining the aqueous solution at pH 8, air was blown in, and an oxidation reaction was performed at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals. Then, after adding ferrous sulfate aqueous solution so that it becomes 0.9 to 1.2 equivalent to the initial alkali amount (sodium component of caustic soda) to this slurry liquid, the slurry liquid is maintained at pH = 8, The oxidation reaction was advanced while blowing air, and the pH was adjusted to about 6 at the end of the oxidation reaction to complete the oxidation reaction. The produced iron oxide particles are washed, filtered, and once taken out, re-dispersed in another water without drying, the pH of the re-dispersed liquid is adjusted, and the n-hexyltrimethoxysilane coupling agent is sufficiently stirred. Was added to 100 parts of magnetic iron oxide and stirred sufficiently. The produced hydrophobic iron oxide particles were washed, filtered and dried by a conventional method, and then the aggregated particles were pulverized to obtain hydrophobic magnetic iron oxide having an average particle size of 0.19 μm.

<Manufacture of toner 1>
An aqueous medium containing a dispersion stabilizer by adding 450 parts of a 0.1M Na ₃ PO ₄ aqueous solution to 720 parts of ion-exchanged water and heating to 60 ° C., and then adding 67.7 parts of a 1.0 M CaCl ₂ aqueous solution. Got.

Styrene 74 parts n-Butyl acrylate 26 parts Divinylbenzene 0.5 part Modified vinyl polymer 1 15 parts Negative charge control agent T-77 (Hodogaya Chemical) 1 part Hydrophobic magnetic iron oxide 1 95 parts The mixture was uniformly dispersed and mixed using a lighter (Mitsui Miike Chemical Co., Ltd.).

  This monomer composition was heated to 60 ° C., and 10 parts of polyethylene wax (maximum endothermic peak in DSC 65 ° C., half-end width of endothermic peak 17 ° C.) was added and dissolved therein. A polymerizable monomer composition was prepared by dissolving 4 parts of butyl-oxy-2-ethylhexanoate.

The polymerizable monomer composition was put into the aqueous medium in the previous period and stirred at 10,000 rpm for 15 minutes in a TK homomixer (Special Machine Industries Co., Ltd.) at 60 ° C. and N ₂ atmosphere. Grained. Thereafter, the mixture was reacted at 80 ° C. for 8 hours while stirring with a paddle stirring blade. After completion of the reaction, the suspension was cooled, hydrochloric acid was added to dissolve the dispersant, the dispersant was dissolved, filtered, washed with water, and dried to obtain toner particles 1.

100 parts of the toner particles and silica having a primary particle diameter of 12 nm are treated with hexamethyldisilazane and then treated with silicone oil, and 1.0 part of hydrophobic silica fine powder having a BET value of 120 m ² / g after the treatment is obtained. Toner 1 was prepared by mixing using a Henschel mixer (Mitsui Miike Chemical Co., Ltd.). Table 2 shows the physical properties of Toner 1.

<Production of Toner 2-6, 8-10>
In the production of Toner 1, the type and amount of the modified vinyl polymer to be used are changed as shown in Table 2, and the same as the production of Toner 1 except that the composition ratio of styrene and n-butyl acrylate is appropriately adjusted. Thus, toners 2 to 6 and 8 to 10 were obtained. The physical properties are shown in Table 2.

<Manufacture of toner 7>
Styrene / n-butyl acrylate copolymer (mass ratio 80/20)
(Mn = 24300, Mw / Mn = 3.0) 100 parts Modified vinyl polymer 1 15 parts Negative charge control agent / T-77 (Hodogaya Chemical) 1 part Hydrophobic magnetic iron oxide 30 parts Polyethylene wax used 5 parts The above materials are mixed in a blender, melt kneaded with a biaxial extruder heated to 110 ° C., the cooled kneaded product is coarsely pulverized with a hammer mill, and the coarsely pulverized product is turbo milled (Turbo Industries Co., Ltd.). The resulting finely pulverized product was subjected to air classification to obtain toner particles.

  Next, the modified vinyl polymer 2 was coarsely pulverized with a hammer mill, and the coarsely pulverized product was finely pulverized with a turbo mill. Thereafter, 15 parts of the pulverized modified vinyl polymer 2 was externally added to 100 parts of the toner particles, and then an impact surface treatment apparatus (treatment temperature 50 ° C., rotary treatment blade peripheral speed 90 m / sec.) Was used. The toner particles were fixed and formed into a film to obtain coated toner particles.

  In the same manner as in the production of Toner 1, 1.0 part of hydrophobic silica fine powder was externally added to 100 parts of the obtained toner particles to prepare Toner 7. Table 2 shows the physical properties of Toner 7 thus obtained.

<Example 1>
As the image forming apparatus, LBP-1760 was remodeled and the one having the structure shown in FIG. 1 was used.

The potential of the electrostatic image bearing member (photoreceptor drum) was set to dark portion potential V _d = −650 V and light portion potential V _L = −130 V. The gap between the electrostatic charge image carrier and the developing sleeve is 270 μm, and the surface of the toner carrier is blasted with a resin layer having a layer thickness of about 7 μm and a JIS centerline average roughness (RA) of 1.0 μm. A developing sleeve formed on an aluminum cylinder having a diameter of 16φ is used, and a developing magnetic pole of 85 mT (850 gauss), a urethane regulating blade having a thickness of 1.0 mm and a free length of 0.5 mm as a toner regulating member is 39.2 N / m (40 g) / Cm).
Phenol resin 100 parts Graphite (particle size approx. 7 μm) 90 parts Carbon black 10 parts

Next, a DC bias component V _dc = −450 V, an overlapping AC bias component V _pp = 1600 V, and F = 2200 Hz were used as the developing bias. The peripheral speed of the developing sleeve was 110% (187 mm / sec) in the forward direction with respect to the peripheral speed of the photoreceptor (170 mm / sec). The transfer bias was set to 1.5 kV DC.

  As a fixing method, there was used a fixing device of LBP-1760 which does not have an oil application function and which is fixed by heating and pressing with a heater through a film. At this time, a pressure roller having a fluororesin surface layer was used, and the diameter of the roller was 30 mm. The fixing temperature was set to 180 ° C. and the nip width was set to 7 mm.

100 g of toner 1 is filled in the cartridge, and the image pattern consists of only a horizontal line with a printing rate of 2% in a normal temperature and humidity environment (23 ° C., 60% RH) and a high temperature and high humidity environment (30 ° C., 80% RH). An image printing test of 3000 sheets was performed. Note that 75 g / m ² of paper was used as the transfer material.

  As a result, the toner 1 had a high density and a good image free from fogging on the non-image area, with no deterioration in fluidity and no occurrence of fusing at the initial stage and after the printing of 3000 sheets. In addition, it was excellent in low-temperature fixability and offset resistance, and was able to take a wide fixing temperature range. Table 3 shows the evaluation results under a normal temperature and humidity environment, and Table 4 shows the evaluation results under a high temperature and high humidity environment.

  The evaluation items described in the examples of the present invention and the comparative examples and the judgment criteria thereof will be described.

(Fixability)
Using a modified LBP-1760 machine, a fixing test was performed in a normal temperature and humidity environment. The image area ratio at this time was 25%, and the applied toner amount per unit area was set to 0.3 mg / cm ² . The process speed was set to 170 mm / sec. The fixing start temperature is measured by adjusting the set temperature of the fixing device every 5 ° C. within a temperature range of 120 to 200 ° C., outputting a fixed image at each temperature, and obtaining the fixed image at 4.9 kPa. The fixing temperature at which the density reduction rate before and after the rubbing was 10% or less was determined as the fixing start temperature by rubbing with a Silbon paper to which a load of (50 g / cm ² ) was applied. Further, regarding the high temperature offset temperature, the stain on the image and the back of the paper was visually evaluated.

(Image density)
The image density formed a solid image portion, and this solid image was measured with a Macbeth reflection densitometer (manufactured by Macbeth).

(Fog)
The fog was measured using a REFECTMETER MODEL TC-6DS manufactured by Tokyo Denshoku. The filter used was a green filter, and fog was calculated from the following formula.
Fog (reflectance) (%) = reflectance on standard paper (%) − reflectance of sample non-image area (%)

The criteria for fogging are as follows.
A: Very good (less than 1.5%)
B: Good (1.5% or more to less than 2.5%)
C: Normal (2.5% or more to less than 4.0%)
D: Poor (4% or more)

(Toner fluidity)
Based on the above-described aggregation degree measurement results, the evaluation standard numerical range was determined as follows. A: Extremely good fluidity: Sample with a measurement result of aggregation degree of 20% or less B: Excellent fluidity: Sample with a measurement result of aggregation degree of 41% to 50% C: Normal fluidity: Measurement of aggregation degree Sample D with a result of 51% to 60%: Poor fluidity: Sample with a measurement result of cohesion 61% to 70% E: Sample with an extremely poor fluidity: measurement with an aggregation measurement of 71% or more

(With or without fusion)
The electrostatic image bearing member and the developing sleeve after the image printing endurance were observed, and the presence or absence of fusion was visually evaluated.

(Blocking resistance)
About 10 g of toner was placed in a 100 ml glass bottle and allowed to stand at 50 ° C. for 5 days.
A: No change B: There is an aggregate, but it loosens immediately C: Hard to loosen D: No fluidity E: Caking

<Example 2 , Reference Examples 3, 4, Example 5, Reference Examples 6, 7 >
Toners 2 to 7 were used as toners, and image printing tests, fixing evaluations, and durability evaluations were performed under the same conditions as in Example 1. As a result, there was no problem in the initial image characteristics, and no problem was obtained for any of the 3000 sheets printed. Table 3 shows the evaluation results under a normal temperature and normal humidity environment, and Table 4 shows the evaluation results under a high temperature and high humidity environment.

<Comparative Examples 1-3>
Toners 8 to 10 were used as toners, and image printing tests, fixing evaluations and durability evaluations were performed under the same conditions as in Example 1. As a result, the toners 8 and 9 were deteriorated in fluidity as well as in the durability test, and particularly in a high-temperature and high-humidity environment, fusing occurred and the image density was significantly reduced. The magnetic toner 10 had a high fixing start temperature. Table 3 shows the evaluation results under a normal temperature and normal humidity environment, and Table 4 shows the evaluation results under a high temperature and high humidity environment.

1 is a schematic diagram illustrating an example of an image forming apparatus used in an embodiment of the present invention. It is explanatory drawing of a developing device structure.

Explanation of symbols

100 photoconductor (image carrier, charged body)
102 Developing sleeve (magnetic toner carrier)
114 Transfer roller (transfer member)
116 Cleaner 117 Charging roller (contact charging member)
121 Laser beam scanner (latent image forming means, exposure device)
124 Feed roller 125 Conveying member 126 Fixing device 140 Developing device 141 Stirring member

Claims (2)

A toner having toner particles containing at least a binder resin, a colorant, and a wax ,
The toner particles are produced in an aqueous medium,
The toner particles have a core and a shell, and the shell of the toner particles contains a modified vinyl polymer modified with polyester,
The polyester modification amount of the modified vinyl polymer is less than 50% by mass,
The acid value of the modified vinyl polymer is 1 mgKOH / g or more and 10.2 mgKOH / g or less ,
The glass transition point of the modified vinyl polymer is 30 ° C. to 80 ° C.,
The modified vinyl polymer is Ri block copolymer der of polyester and vinyl polymer,
The toner contains 5 to 50 parts by mass of the modified vinyl polymer with respect to 100 parts by mass of the binder resin . The toner according to claim 1, wherein the toner particles contain iron oxide as a colorant.

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