JP5749679B2 - Toner for electrostatic image development - Google Patents

Description

  The present invention relates to a toner for developing an electrostatic image.

  In general, in electrophotography, the surface of an electrostatic latent image carrier is charged by corona discharge or the like, and then exposed to a laser or the like to form an electrostatic latent image. The electrostatic latent image is developed with toner. A toner image is formed, and the toner image is further transferred to a recording medium to obtain a high quality image. In general, toners applied to these development methods are mixed with a binder resin such as a thermoplastic resin, a colorant, a charge control agent, a release agent, a magnetic material, etc., kneaded, pulverized, and classified to have an average particle size of 5 A toner particle having a size of 10 μm to 10 μm is used. For the purpose of imparting fluidity to the toner, controlling the charging of the toner, and improving the cleaning properties of the toner from the latent image carrier, inorganic fine powders such as silica and titanium oxide are used as toner base particles. It is externally added to the surface.

  With respect to such toner, from the viewpoints of energy saving, apparatus miniaturization, and the like, there is a demand for a toner having excellent low-temperature fixability that can be satisfactorily fixed without heating the fixing roller as much as possible. However, toners with excellent low-temperature fixability often use a binder resin with a low melting point or glass transition point or a release agent with a low melting point, and generally tend to aggregate when stored at high temperatures. In addition, there is a problem that offset is likely to occur due to the toner fusing to the heated fixing roller.

  Therefore, for the purpose of obtaining good fixability at a wide range of temperatures in the low temperature range, the purpose of improving storage stability at high temperatures, the purpose of improving blocking resistance, etc., toner core particles using a binder resin having a low melting point are used. In addition, a capsule toner is used which is coated with a resin having a Tg higher than the glass transition point (Tg) of the binder resin of the toner core particles.

  As such a capsule toner, a fluidized layer of colored resin particles (A) having a volume average particle diameter of 3 μm to 10 μm is formed by an air flow, and the resin particles (B) having a particle diameter of 0.1 to 1 μm are formed. The dispersion is applied to the surface of the colored resin particles (A) with a spray nozzle and then dried, and the dried particles are subjected to mechanical stress on the fine resin particles by colliding with the stirring blades or mesh screen. A capsule toner in which resin fine particles are fixed on the toner surface has been proposed (Patent Document 1). Further, the amount of deformation of the toner according to the pressure applied to the toner is evaluated by an apparatus using a microindentation method (picodenter), and the toner is defined by its suitable value, and is manufactured by an emulsion aggregation method. A toner in which toner core particles are coated with a resin particle shell has been proposed (Patent Document 2).

JP 2006-301373 A JP 2010-1113017 A

  However, when the toner described in Patent Document 1 is produced, a large amount of heat is generated due to mechanical stress when the resin fine particles are fixed on the surface of the toner base particles (colored resin particles (A)). For this reason, the toner described in Patent Document 1 has a problem that components such as a release agent contained in the toner base particles tend to ooze out on the surface of the toner.

  When the release agent oozes out to the surface of the toner, when the toner is stored at a high temperature, agglomeration occurs, or when forming an image, an image defect due to adhesion of the toner to the developing sleeve, or toner An image defect such as a fog due to the charging failure may occur in the formed image.

  Regarding the toner described in Patent Document 1, it is conceivable to reduce the content of the release agent filled in the binder resin in order to suppress the release of the release agent to the toner surface. However, in this case, it is difficult to obtain a toner having excellent releasability and high temperature offset resistance.

  Further, in the toner described in Patent Document 1, since resin fine particles having a high Tg are firmly embedded in the toner base particles, a toner that can be satisfactorily fixed at a low temperature may not be obtained.

  With respect to the toner described in Patent Document 2, by optimizing the deformation amount of the toner in accordance with the pressure, the melting characteristics at the time of fixing the toner can be satisfied, but further improvement of the melting characteristics at the time of toner fixing is required. Therefore, even if the toner is defined only by the deformation amount of the toner according to the pressure, the requirement cannot be satisfied.

  The present invention has been made in view of such circumstances, is excellent in heat-resistant storage stability and low-temperature fixability, can suppress the occurrence of offset at a high temperature, and in a formed image, image defects due to adhesion of toner to a developing sleeve and An object of the present invention is to provide an electrostatic charge image developing toner capable of suppressing image defects such as fogging.

  The inventors of the present invention are toners for developing electrostatic images in which the surface of core particles composed of fine particles of a binder resin having a predetermined storage elastic modulus is coated with resin fine particles having a predetermined storage elastic modulus. In order to complete the present invention, it is found that an electrostatic charge image developing toner having a Young's modulus at 25 ° C. of 100 to 150 MPa and a crushing strength at 25 ° C. of 20 MPa or more can solve the above problems. It came. More specifically, the present invention provides the following.

The present invention comprises at least one resin selected from the group consisting of a (meth) acrylic resin and a styrene- (meth) acrylic resin, at least the surface of the core particle containing a binder resin made of a polyester resin. An electrostatic charge image developing toner coated with resin fine particles,
The core resin binder resin fine particles have a storage elastic modulus at 100 ° C. of 1.0 × 10 ^{1 to} 2.0 × 10 ⁵ Pa and a storage elastic modulus at 150 ° C. of 1.0 to 2.5 ×. 10 ² Pa,
The resin fine particles have a storage elastic modulus at 100 ° C. of 2.5 × 10 ^{5 to} 2.0 × 10 ⁶ Pa and a storage elastic modulus at 150 ° C. of 6.0 × 10 ^{2 to} 2.0 × 10 ⁴ Pa. And
The present invention relates to an electrostatic charge image developing toner having a Young's modulus at 25 ° C. of 100 to 150 MPa and a crushing strength at 25 ° C. of 20 MPa or more.

  According to the present invention, excellent heat-resistant storage stability and low-temperature fixability, can suppress the occurrence of offset at high temperature, excellent releasability between the fixing roller and the recording medium on which the image is formed, in the formed image, It is possible to provide an electrostatic charge image developing toner capable of suppressing image defects due to adhesion of toner to the developing sleeve and image defects such as fogging.

It is a figure explaining the measuring method of the softening point by an elevating type flow tester.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. . In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited.

  In the electrostatic image developing toner of the present invention (hereinafter also referred to as toner), the surface of core particles containing a binder resin having a predetermined storage elastic modulus is coated with resin fine particles having a predetermined storage elastic modulus. A toner for developing an electrostatic image, having a Young's modulus at 25 ° C. of 100 to 150 MPa and a crushing strength at 25 ° C. of 20 MPa or more.

  The electrostatic charge image developing toner of the present invention is for electrostatic charge image development in which the surface of core particles containing fine particles of a binder resin having a predetermined storage modulus is coated with resin fine particles having a predetermined storage modulus. The toner is not limited as long as the toner has a predetermined Young's modulus and crushing strength. As a preferred structure of the toner for electrostatic charge development of the present invention, the surface of the core particle in which a colorant, a charge control agent, a release agent, magnetic powder and the like are blended in a binder resin as necessary is a resin. A structure coated with fine particles is preferable. When the toner has such a structure, it is easy to adjust the Young's modulus of the toner by using core particles containing binder resins having different elasticity. In this case, the crushing strength of the toner can be easily adjusted by using resin fine particles made of resins having different mechanical characteristics.

  The toner for developing an electrostatic charge image can further have an external additive attached to the surface thereof. Further, the toner of the present invention can be mixed with a carrier and used as a two-component developer, if desired.

  Hereinafter, when the toner for developing an electrostatic charge image of the present invention is composed of core particles and resin fine particles covering the core particles, the core particles, the resin fine particles, and the method for producing the toner will be described in order.

≪Core particle≫
When the toner of the present invention is composed of core particles and resin fine particles that coat the core particles, the core particles essentially contain a binder resin. Moreover, the core particle may contain the coloring agent, the charge control agent, the mold release agent, the magnetic powder, etc. in the binder resin as necessary. Hereinafter, the production method of the binder resin, the colorant, the release agent, the charge control agent, the magnetic powder, and the core particles will be described in order.

[Binder resin]
The core particles essentially contain a binder resin. The binder resin has a storage elastic modulus at 100 ° C. of the fine particles of 1.0 × 10 ^{1 to} 2.0 × 10 ⁵ Pa, and a storage elastic modulus at 150 ° C. of 1.0 to 2.5 × 10 ² Pa. From a resin conventionally used as a binder resin for toner, it is appropriately selected in consideration of the Young's modulus and crushing strength of toner obtained using core particles.

  Examples of resins conventionally used as binder resins for toner include styrene resins, acrylic resins, styrene acrylic resins, polyethylene resins, polypropylene resins, vinyl chloride resins, polyester resins, polyamide resins, Examples thereof include thermoplastic resins such as polyurethane resin, polyvinyl alcohol resin, vinyl ether resin, N-vinyl resin, and styrene-butadiene resin. Among these resins, it is easy to obtain a core particle that gives a toner excellent in dispersibility of the colorant in the toner, toner charging property, and fixing property to paper, and the core particle is used to obtain a predetermined Young's modulus and crushing strength. A polyester resin is preferable because it is easy to form a toner having the following.

  The volume average particle diameter of the core particles of the toner of the present invention is not particularly limited as long as the object of the present invention is not impaired, but is preferably 5 to 10 μm. The volume average particle diameter of the core particles is appropriately determined in consideration of the amount of resin fine particles used so that the volume average particle diameter of the toner obtained by coating the core particles with the resin fine particles becomes a desired value.

  The softening point of the binder resin is not particularly limited as long as the toner obtained using the core particles has a predetermined Young's modulus and crushing strength. Typically, the softening point of the binder resin is preferably 60 to 100 ° C, more preferably 70 to 95 ° C. If the softening point of the binder resin is too high, the toner obtained using the core particles does not adhere to the developing sleeve, but it may be difficult to fix the toner well at a low temperature. If the softening point of the binder resin is too low, adhesion of the toner obtained by using the core particles to the developing sleeve and heat resistant storage stability of the toner may be impaired. The softening point of the binder resin can be measured according to the following method.

<Softening point measurement method>
The softening point of the binder resin (toner) is measured with a Koka flow tester (CFT-500D (manufactured by Shimadzu Corporation)). Using a binder resin of 1.5 g as a sample, using a die having a height of 1.0 mm and a diameter of 1.0 mm, a heating rate of 4 ° C./min, a preheating time of 300 seconds, a load of 5 kg, and a measurement temperature range of 60 to 200 Measure under the condition of ° C. The softening point is read from an S-shaped curve relating to temperature (° C.) and stroke (mm) obtained by the flow tester measurement.

  A method of reading the softening point will be described with reference to FIG. The maximum stroke value is S1, and the baseline stroke value on the low temperature side is S2. The temperature at which the stroke value is (S1 + S2) / 2 in the S-shaped curve is defined as the softening point of the measurement sample.

  The glass transition point (Tg) of the binder resin is not particularly limited as long as the toner obtained using the core particles has a predetermined Young's modulus and crushing strength. Typically, Tg of the binder resin is preferably 30 to 60 ° C, and more preferably 35 to 55 ° C. If the Tg of the binder resin is too low, the strength of the toner particles obtained using the core particles tends to decrease, and the toner particles may aggregate in a high temperature and high humidity environment. On the other hand, if the Tg of the binder resin is too low, the Young's modulus of the toner obtained using the core particles tends to be less than 100 MPa. If the Tg of the binder resin is too high, it may be difficult to satisfactorily fix the toner obtained using the core particles at a low temperature. If the Tg of the binder resin is too high, the Young's modulus of the toner obtained using the core particles tends to exceed 150 MPa. The glass transition point of the binder resin can be measured according to the following method.

<Glass transition point measurement method>
The glass transition point of the binder resin can be obtained from the change point of specific heat using a differential scanning calorimeter (DSC). More specifically, it can be determined by measuring the endothermic curve of the binder resin using a differential scanning calorimeter DSC-6200 manufactured by Seiko Instruments Inc. as a measuring device. An endothermic curve obtained by placing 10 mg of a measurement sample in an aluminum pan, using an empty aluminum pan as a reference, and measuring at a measurement temperature range of 25 to 200 ° C. and a temperature increase rate of 10 ° C./min. The glass transition point can be obtained more.

  The number average molecular weight (Mn) of the binder resin is not particularly limited as long as the toner obtained using the core particles has a predetermined Young's modulus and crushing strength. Typically, the number average molecular weight (Mn) of the binder resin is preferably 1,000 to 5,000, and more preferably 1,500 to 3,000. The molecular weight distribution (Mw / Mn) represented by the ratio of the number average molecular weight (Mn) to the mass average molecular weight (Mw) is preferably 1.5 to 5.0, more preferably 1.8 to 4.0. preferable. By setting the molecular weight distribution of the binder resin in such a range, it becomes easy to suppress the occurrence of offset when an image is formed with the toner obtained using the core particles. The number average molecular weight (Mn) and the mass average molecular weight (Mw) of the binder resin can be measured by gel permeation chromatography.

  Further, the acid value of the binder resin is preferably 5 to 30 mgKOH / g. If the acid value of the binder resin is too low, when the core particles are produced by a method of aggregating the fine particles, the aggregation of the fine particles may not proceed well. If the acid value of the binder resin is too high, various performances of the toner obtained using the core particles are likely to be impaired due to the influence of humidity under high humidity conditions.

In addition, the binder resin fine particles used as a material constituting the core particles have a storage elastic modulus measured according to the following method of 1.0 × 10 ^{1 to} 2.0 × 10 ⁵ Pa at 100 ° C. At 150 ° C., the pressure is 1.0 to 2.5 × 10 ² Pa. By using fine particles containing a binder resin having a storage elastic modulus in this range as a material constituting the core particles, a toner capable of suppressing toner adhesion to the developing sleeve can be obtained.

<Method for measuring storage modulus>
Using a measuring device (MCR301 (Anton Pearl Japan Co., Ltd.)), the storage elastic modulus was measured under the following conditions. 0.35 g of resin was pressed into pellets (thickness: about 1.0 mm) with a φ20 tablet press at 60 kg · f / cm ² for 15 seconds. This was placed on a plate diameter of 20 mm (DISPO — 20), and each resin was welded at (Tm + 3) ° C. Subsequently, the temperature was lowered to 30 ° C. at a constant 0.01% strain at 10 ° C./min, and then increased to 200 ° C. at a rate of 2 ° C./min while increasing the strain amount linearly from 0.01% to 5%. The storage elastic modulus at 150 ° C. and 150 ° C. was measured.

  Hereinafter, the polyester resin constituting the binder resin contained in the core particles will be described.

[Polyester resin]
As the polyester resin, those obtained by condensation polymerization or co-condensation polymerization of a divalent or trivalent or higher alcohol component and a divalent or trivalent or higher carboxylic acid component can be used. The components used when synthesizing the polyester resin include the following alcohol components and carboxylic acid components.

  Specific examples of the divalent or trivalent or higher alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1 Diols such as 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A, Bisphenols such as hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, Entaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4- Examples include trivalent or higher alcohols such as butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

  Specific examples of the divalent or trivalent or higher carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, Sebacic acid, azelaic acid, malonic acid, or n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid Divalent carboxylic acids such as acids, isododecyl succinic acid, isododecenyl succinic acid and the like or alkyl or alkenyl succinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid Acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalene Tricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, And trivalent or higher carboxylic acids such as tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empole trimer acid. These divalent or trivalent or higher carboxylic acid components may be used as ester-forming derivatives such as acid halides, acid anhydrides, and lower alkyl esters. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

  The acid value of the polyester resin can be adjusted by adjusting the balance of the functional groups of the hydroxyl group of the alcohol component used for the synthesis of the polyester resin and the carboxyl group of the carboxylic acid component.

  Although the polyester resin constituting the binder resin has been described above, an amorphous polyester resin is preferable among the polyester resins because the toner obtained using the core particles is excellent in low-temperature fixability. Hereinafter, the amorphous polyester resin will be described.

(Polyester resin)
As a monomer used when synthesizing a polyester resin, the above divalent or trivalent or higher alcohol component or divalent or trivalent or higher carboxylic acid component can be used. In the specification and claims of the present application, the polyester resin is a polyester resin having a crystallinity index of 1.20 or more, preferably 1.50 to 3.00. The crystallinity index of the polyester resin can be adjusted by appropriately adjusting the type and amount of the alcohol component and carboxylic acid component that are monomers.

  The crystallinity index of the polyester resin can be determined by the ratio between the softening point of the polyester resin and the maximum peak temperature of heat of fusion (softening point / maximum peak temperature of heat of fusion). The softening point of the polyester resin is measured by a flow tester described later, and the maximum peak temperature of the heat of fusion is measured by a differential scanning calorimeter (DSC) described later.

When preparing a polyester resin, it is necessary to suppress crystallization of the obtained polyester resin. The method for suppressing crystallization of the polyester resin is not particularly limited. Examples of suitable crystallization suppressing methods include the following methods 1) to 3).
1) A method in which only a small amount of an alcohol component and a carboxylic acid component that promote crystallization are used or not.
2) The method of using 2 or more types of compounds, respectively as an alcohol component and a carboxylic acid component.
3) A method for suppressing crystallization using an alkylene oxide adduct of bisphenol A, an alkyl-substituted succinic acid, or the like.
Examples of the alcohol component that facilitates crystallization of the polyester resin include aliphatic diols having 2 to 8 carbon atoms, and among aliphatic diols, α, ω-alkanes having 2 to 8 carbon atoms are particularly preferable. Diols are mentioned. Examples of the carboxylic acid component that facilitates the crystallization of the polyester resin include aliphatic dicarboxylic acids having 2 to 16 carbon atoms. Among aliphatic dicarboxylic acids, in particular, α, ω-alkanedicarboxylic acid.

  Among the above-described methods for suppressing crystallization, the method 3) is more preferable because the number of types of monomers is small and the preparation of an amorphous polyester resin is easy. In the method of 3), the crystallization is easily suppressed as the amount of the alkylene oxide adduct of bisphenol A and the alkyl-substituted succinic acid is increased. However, the amount of these monomers used depends on the crystallization of the resulting polyester resin. It adjusts suitably considering the degree and other physical properties.

  A polyester resin may be used independently and may be used in combination of 2 or more type.

[Colorant]
When the toner of the present invention is composed of core particles and resin fine particles covering the core particles, the core particles may contain a colorant, if necessary. As the colorant contained in the core particle, a known pigment or dye can be used according to the color of the toner particle. Specific examples of suitable colorants that can be contained in the core particles include the following colorants.

  Examples of the black colorant include carbon black. Further, as the black colorant, a colorant that is toned in black using a colorant such as a yellow colorant, a magenta colorant, and a cyan colorant, which will be described later, can also be used. When the toner is a color toner, examples of the colorant blended in the core particles include a yellow colorant, a magenta colorant, and a cyan colorant.

  Examples of the yellow colorant include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specifically, C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 191, 194; Nephthol Yellow S, Hansa Yellow G, and C.I. I. Examples thereof include bat yellow.

  Examples of the magenta colorant include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 19, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221 and 254.

  Examples of cyan colorants include copper phthalocyanine compounds, copper phthalocyanine derivatives, anthraquinone compounds, and basic dye lake compounds. Specifically, C.I. I. Pigment blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66, etc .; phthalocyanine blue, C.I. I. Bat Blue, and C.I. I. Acid blue and the like.

  The amount of the colorant used in the core particles is not particularly limited as long as the object of the present invention is not impaired. Specifically, 1 to 20 parts by mass is preferable with respect to 100 parts by mass of the binder resin, and 3 to 10 parts by mass is more preferable.

[Release agent]
When the toner of the present invention is composed of core particles and resin fine particles covering the core particles, the core particles may contain a release agent as necessary. The release agent is usually used for the purpose of improving the toner fixing property and offset resistance. The type of release agent is not particularly limited as long as it is conventionally used as a release agent for toner.

  Suitable release agents include, for example, aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; Oxides of aliphatic hydrocarbon waxes such as block copolymers of polyethylene wax and oxidized polyethylene wax; plant waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax, and rice wax; beeswax, lanolin, and whale wax Animal waxes such as ozokerite, ceresin, and vetrolactam; waxes based on fatty acid esters such as montanate ester wax and castor wax; deacidified carnauba wax Some fatty acid esters of the scan or the like, or de-oxidized waxes whole.

  Examples of a mold release agent that can be suitably used include palmitic acid, stearic acid, montanic acid, and saturated linear fatty acids such as long-chain alkyl carboxylic acids having a long-chain alkyl group; brassic acid, eleostearic acid, And unsaturated fatty acids such as valinal acid; saturated alcohols such as stearyl alcohol, eicosyl alcohol, behenyl alcohol, carnauvyl alcohol, seryl alcohol, melyl alcohol, and long-chain alkyl alcohols having a long-chain alkyl group; sorbitol, etc. Polyhydric alcohols; fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, and hexamethylene bis stearic acid amide Saturated fatty acid bisamides; ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide and the like, m-xylene Aromatic bisamides such as bis-stearic acid amide and N, N′-distearylisophthalic acid amide; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate, and magnesium stearate; Waxes grafted with vinyl monomers such as styrene and acrylic acid; partially esterified products of fatty acids such as behenic acid monoglyceride and polyhydric alcohols; methyl ester compounds having hydroxyl groups obtained by hydrogenating vegetable oils and fats Mentioned That.

  The amount of the release agent used is not particularly limited as long as the object of the present invention is not impaired. As for the specific usage-amount of a mold release agent, 1-30 mass parts is preferable with respect to 100 mass parts of binder resin, and 5-20 mass is more preferable. If the amount of the release agent used is too small, the desired effect may not be obtained in terms of suppressing the occurrence of offset and image smearing in the formed image. If the amount of release agent used is excessive, In some cases, the storage stability may be reduced by fusing.

[Charge control agent]
When the toner of the present invention is composed of core particles and resin fine particles covering the core particles, the core particles may contain a charge control agent as required. The charge control agent improves the stability of the charge level of the toner and the charge rise characteristic that is an indicator of whether the toner can be charged to a predetermined charge level in a short time. Used for gaining purposes. When developing with positively charged toner, a positively chargeable charge control agent is used. When developing with negatively charged toner, a negatively chargeable charge control agent is used.

  The charge control agent that can be suitably used is not particularly limited as long as the object of the present invention is not impaired, and can be appropriately selected from charge control agents conventionally used in toners. Specific examples of the positively chargeable charge control agent include pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1, 2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, Azine compounds such as phthalazine, quinazoline, quinoxaline; azine fast red FC, azine fast red 12BK, azine violet BO, azine Direct dyes composed of azine compounds such as Raun 3G, azine light brown GR, azine dark green BH / C, azine deep black EW, and azine deep black 3RL; nigrosine compounds such as nigrosine, nigrosine salts, nigrosine derivatives; Acid dyes comprising nigrosine compounds such as BK, nigrosine NB, and nigrosine Z; metal salts of naphthenic acid or higher fatty acids; alkoxylated amines; alkylamides; quaternary ammonium salts such as benzylmethylhexyldecylammonium and decyltrimethylammonium chloride It is done. These positively chargeable charge control agents can be used in combination of two or more.

  A resin having a quaternary ammonium salt, carboxylate, or carboxyl group as a functional group can also be used as a positively chargeable charge control agent. More specifically, a styrene resin having a quaternary ammonium salt, an acrylic resin having a quaternary ammonium salt, a styrene-acrylic resin having a quaternary ammonium salt, a polyester resin having a quaternary ammonium salt, a carboxylic acid Styrene resin having salt, acrylic resin having carboxylate, styrene-acrylic resin having carboxylate, polyester resin having carboxylate, styrene resin having carboxyl group, acrylic having carboxyl group 1 type, or 2 or more types, such as resin, the styrene-acrylic resin which has a carboxyl group, and the polyester-type resin which has a carboxyl group, are mentioned. The molecular weight of these resins is not particularly limited as long as the object of the present invention is not impaired, and may be an oligomer or a polymer.

  Among the resins that can be used as positively chargeable charge control agents, styrene-acrylic resins having a quaternary ammonium salt as a functional group are preferred because the charge amount can be easily adjusted to a value within a desired range. More preferred. In the styrene-acrylic resin having a quaternary ammonium salt as a functional group, specific examples of a preferable acrylic comonomer copolymerized with a styrene unit include methyl acrylate, ethyl acrylate, n-propyl acrylate, and iso-acrylate. (Meth) acrylic acid such as propyl, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate Examples include alkyl esters.

  As the quaternary ammonium salt, a unit derived from a dialkylaminoalkyl (meth) acrylate, dialkylamino (meth) acrylamide, or dialkylaminoalkyl (meth) acrylamide through a quaternization step is used. Specific examples of the dialkylaminoalkyl (meth) acrylate include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate and the like. Specific examples of dialkyl (meth) acrylamide include dimethylmethacrylamide, and specific examples of dialkylaminoalkyl (meth) acrylamide include dimethylaminopropylmethacrylamide. Further, hydroxy group-containing polymerizable monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and N-methylol (meth) acrylamide can be used in combination during polymerization.

  Specific examples of the negatively chargeable charge control agent include organometallic complexes and chelate compounds. Examples of organometallic complexes and chelate compounds include acetylacetone metal complexes such as aluminum acetylacetonate and iron (II) acetylacetonate, and salicylic acid metal complexes or salicylic acid systems such as chromium 3,5-di-tert-butylsalicylate. Metal salts are preferable, and salicylic acid metal complexes or salicylic acid metal salts are more preferable. These negatively chargeable charge control agents can be used in combination of two or more.

  The amount of the positively or negatively chargeable charge control agent used is not particularly limited as long as the object of the present invention is not impaired. Typically, the amount of the positively or negatively chargeable charge control agent used is preferably 0.5 to 20.0 parts by mass, and preferably 1.0 to 15. 0 parts by mass is more preferable. If the amount of charge control agent used is too small, it is difficult to stably charge the toner to a predetermined polarity, making it difficult to maintain the image density over a long period of time, because the image density of the formed image is less than the desired value. Sometimes it becomes. Further, in this case, the charge control agent is difficult to uniformly disperse in the binder resin, and the formed image is likely to be fogged or the latent image carrying part is likely to be contaminated. When the amount of the charge control agent used is excessive, image defects in the formed image due to poor charging under high temperature and high humidity due to deterioration in environmental resistance, contamination of the latent image carrier, and the like are likely to occur.

[Magnetic powder]
When the toner of the present invention is composed of core particles and resin fine particles covering the core particles, the core particles may contain magnetic powder as necessary. The electrostatic charge image developing toner can be blended with magnetic powder as desired. The kind of magnetic powder is not particularly limited as long as the object of the present invention is not impaired. Examples of suitable magnetic powders include: irons such as ferrite and magnetite; ferromagnetic metals such as cobalt and nickel; alloys containing iron and / or ferromagnetic metals; compounds containing iron and / or ferromagnetic metals; A ferromagnetic alloy subjected to a ferromagnetization treatment such as chromium dioxide.

  The particle size of the magnetic powder is not limited as long as the object of the present invention is not impaired. The particle diameter of the specific magnetic powder is preferably 0.1 to 1.0 μm, and more preferably 0.1 to 0.5 μm. When magnetic powder having a particle diameter in such a range is used, it is easy to uniformly disperse the magnetic powder in the binder resin.

  The magnetic powder can be used that has been surface-treated with a surface treating agent such as a titanium coupling agent or a silane coupling agent for the purpose of improving dispersibility in the toner.

  The usage-amount of magnetic powder is not specifically limited in the range which does not inhibit the objective of this invention. When the toner is used as a one-component developer, the specific amount of the magnetic powder is preferably 35 to 60 parts by mass, more preferably 40 to 60 parts by mass when the total amount of toner is 100 parts by mass. When the amount of magnetic powder used is excessive, it may be difficult to maintain a desired image density when an image is formed over a long period of time, or fixability may be extremely reduced. When the amount of magnetic powder used is too small, the formed image tends to be fogged, and the durability of the image density may be reduced. When the toner is used as a two-component developer, the amount of magnetic powder used is preferably 20% by mass or less and more preferably 15% by mass or less when the total amount of toner is 100 parts by mass.

[Method for producing core particles]
When the toner of the present invention is composed of core particles and resin fine particles covering the core particles, the core particles contain a predetermined component, and give a toner having a predetermined Young's modulus and crushing strength If so, the manufacturing method is not particularly limited. Suitable methods for producing the core particles include a melt-kneading method and an agglomeration method.

  In the melt-kneading method, a binder resin and optional components such as a colorant, a release agent, a charge control agent, and magnetic powder are mixed, and then the mixture is melt-kneaded, and the resulting melt-kneaded product is pulverized and classified. Thus, a core particle having a desired particle size is obtained.

  In the aggregation method, fine particles containing at least fine particles containing a binder resin are aggregated in an aqueous medium to obtain an aqueous medium dispersion of fine particle aggregates containing a binder resin, and then the obtained fine particle aggregates are obtained. The aqueous medium dispersion liquid is heated to obtain core particles having a desired particle size with controlled shape.

  Among these core particle production methods, the coagulation method is preferred because it is easy to obtain core particles having a uniform shape, and it is easy to form a toner with little variation in Young's modulus and crushing strength using the core particles. Hereinafter, the aggregation method will be described in detail.

  The agglomeration method will be described in the order of fine particle preparation, fine particle aggregation, and fine particle coalescence.

(Preparation of fine particles)
The method for preparing the fine particles containing the binder resin is not particularly limited. The fine particles containing the binder resin are fine particles of the binder resin, or fine particles of a resin composition containing the binder resin and optional components such as a colorant, a release agent, and a charge control agent. Usually, fine particles containing a binder resin are prepared as an aqueous medium dispersion of fine particles by making the binder resin or a composition containing the binder resin into a desired size in an aqueous medium. The aqueous dispersion of fine particles may contain fine particles other than the fine particles containing the binder resin. Examples of fine particles other than fine particles containing a binder resin include fine particles of a colorant, fine particles of a release agent, and fine particles composed of a colorant and a release agent. Hereinafter, a method for preparing fine particles containing a binder resin, a method for preparing fine particles of a colorant, and a method for preparing fine particles of a release agent will be described in order. In addition, about the microparticles | fine-particles containing a component different from the microparticles | fine-particles demonstrated here, it can prepare by selecting suitably the manufacturing method of these microparticles | fine-particles.

<Preparation of fine particles containing binder resin>
First, a resin composition containing a binder resin or a binder resin and optional components that may be contained in core particles is roughly pulverized by a pulverizer such as a turbo mill. While the coarsely pulverized product is dispersed in an aqueous medium such as ion-exchanged water, it is heated to a temperature that is 10 ° C. higher than the softening point of the binder resin measured by a flow tester (at a maximum temperature of about 200 ° C.). By applying a strong shearing force to the heated binder resin dispersion with a high-speed shearing emulsifier such as CLEARMIX, a dispersion of fine particles containing the binder resin in an aqueous medium can be obtained.

  A surfactant is preferably added to the aqueous medium. By adding a surfactant to the aqueous medium, fine particles of the binder resin composition can be favorably progressed, and a dispersion of fine particles having excellent dispersion stability can be easily obtained.

  When the binder resin is a resin having an acidic group, the specific surface area of the binder resin is increased by atomizing the binder resin in an aqueous medium as it is. The pH of the aqueous medium may drop to about 3-4. In this case, the polyester resin that is the binder resin may be hydrolyzed, or the particle diameter of the obtained fine particles may be difficult to be reduced to a desired particle diameter.

  In order to suppress such problems, it is preferable to add a basic substance to the aqueous medium when preparing the fine particles containing the binder resin. The basic substance is not particularly limited as long as the above problem can be suppressed. For example, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, alkalis such as sodium carbonate, and potassium carbonate can be used. Alkali metal hydrogen carbonates such as metal carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate, N, N-dimethylethanolamine, N, N-diethylethanolamine, triethanolamine, tripropanolamine, tributanolamine, triethylamine, Examples thereof include nitrogen-containing organic bases such as n-propylamine, n-butylamine, isopropylamine, monomethanolamine, morpholine, methoxypropylamine, pyridine and vinylpyridine.

<Preparation of fine particles of colorant>
In an aqueous medium containing a surfactant, the colorant and, if necessary, a component such as a colorant dispersant are dispersed by a known disperser to obtain fine particles of the colorant. The type of the surfactant is not particularly limited, and any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used. The amount of the surfactant used is not particularly limited, but is preferably not less than the critical micelle concentration (CMC).

<Preparation of fine particles of release agent>
The release agent is coarsely pulverized to about 100 μm or less in advance. The coarsely pulverized product of the release agent is added to an aqueous medium containing a surfactant, and the slurry is heated to a temperature equal to or higher than the melting point of the release agent. A strong shearing force is applied to the heated slurry using a homogenizer or a pressure discharge type disperser to prepare a fine particle dispersion containing a release agent.

  In many cases, the release agent usually has a melting point of 100 ° C. or lower. In this case, the release agent can be heated to the melting point or higher under atmospheric pressure, and fine particles can be formed using a normal homogenizer. When the melting point of the mold release agent exceeds 100 ° C., the mold release agent can be made fine by performing fine particle formation using a pressure-resistant type apparatus.

(Aggregation of fine particles)
The fine particles containing the binder resin prepared by the above method are appropriately combined with fine particles containing a release agent and fine particles containing a colorant so that the core particle contains a predetermined component to form fine particle aggregates. The The method for aggregating the fine particles is not particularly limited as long as the object of the present invention is not impaired. A suitable method for aggregating the fine particles includes a method of adding an aggregating agent to the fine particle dispersion in the aqueous medium.

  Examples of the flocculant include inorganic metal salts, inorganic ammonium salts, divalent or higher metal complexes, and the like. Examples of inorganic metal salts include metal salts such as sodium sulfate, sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and polyaluminum chloride and polyaluminum hydroxide. An inorganic metal salt polymer is mentioned. Examples of the inorganic ammonium salt include ammonium sulfate, ammonium chloride, and ammonium nitrate. Further, a quaternary ammonium salt type cationic surfactant, polyethyleneimine and the like can also be used as a flocculant.

  As the flocculant, a divalent metal salt and a monovalent metal salt are preferably used. A divalent metal salt and a monovalent metal salt are preferably used in combination. Since the divalent metal salt and the monovalent metal salt have different agglomeration speeds, the particle size distribution can be controlled while controlling the increase in the particle diameter of the obtained fine particle aggregate by using them together. Easy to sharpen.

  The addition amount of the flocculant is not particularly limited as long as the object of the present invention is not impaired, and is preferably 0.1 to 10 mmol / g with respect to the solid content of the fine particle dispersion. Further, the addition amount of the flocculant is preferably adjusted as appropriate according to the type and amount of the surfactant contained in the fine particle dispersion.

  The flocculant is added at a temperature not higher than the glass transition point of the binder resin after adjusting the pH of the fine particle dispersion. In particular, when the binder resin is a polyester resin, the flocculant is added after adjusting the pH of the fine particle dispersion to the alkali side, preferably to pH 10 or higher. Thereby, uniform aggregation can be performed and the particle size distribution of the fine particle aggregate can be sharpened. The flocculant may be added at one time or may be added sequentially.

  After the aggregation has progressed until the fine particle aggregate has a desired particle size, an aggregation terminator is preferably added. Examples of the aggregation terminator include sodium chloride, potassium chloride, magnesium chloride and the like. Thus, a fine particle aggregate can be obtained.

(Unification of fine particles)
The dispersion of the fine particle aggregate obtained in the above manner in an aqueous medium is heated to unite the components contained in the fine particle aggregate to obtain core particles whose shape is controlled to a desired particle diameter. In uniting the fine particle aggregates, the temperature at which the dispersion liquid of the fine particle aggregates in the aqueous medium is heated is not particularly limited as long as the object of the present invention is not impaired. Typically, the dispersion of the fine particle aggregate in the aqueous medium is preferably heated to a temperature not lower than the glass transition point of the binder resin and not higher than the melting point of the binder resin, and the glass transition point of the binder resin +10. More preferably, it is heated to a temperature not lower than the degree C and not higher than the melting point of the binder resin. By heating the dispersion liquid of the fine particle aggregate in the aqueous medium to such a temperature, the coalescence of the components contained in the fine particle aggregate can be favorably progressed.

  When the toner of the present invention is composed of core particles and resin fine particles covering the core particles, the core particles prepared by the above-described method are recovered from the dispersion in the aqueous medium or the aqueous medium and dried. It is covered with resin fine particles, which will be described later, in the form of powder.

≪Resin fine particles covering core particles≫
When the toner of the present invention is composed of core particles and resin fine particles covering the core particles, resin fine particles made of various resins can be used as long as the toner has a predetermined Young's modulus and crushing strength. .

  The method for producing the resin fine particles covering the core particles is not particularly limited, and the emulsion polymerization method is preferable because the particle diameter of the resin fine particles can be easily controlled and the resin fine particles having the same particle diameter can be easily prepared.

  The volume average particle diameter of the resin fine particles covering the core particles is not particularly limited as long as the toner in which the core particles are coated with the resin fine particles has a predetermined Young's modulus and crushing strength. The volume average particle diameter of the resin fine particles covering the core particles is preferably 0.03 to 0.50 μm, and more preferably 0.05 to 0.30 μm. When the volume average particle diameter of the resin fine particles covering the core particles is in such a range, it is easy to uniformly coat the core particles and to prepare a toner having a predetermined crushing strength. The volume average particle diameter of the resin fine particles covering the core particles can be measured by, for example, an electrophoretic light scattering photometer (LA-950V2 (manufactured by Horiba, Ltd.)).

  The softening point of the resin fine particles covering the core particles is not particularly limited as long as the toner in which the core particles are coated with the resin fine particles has a predetermined Young's modulus and crushing strength. Typically, the softening point of the resin fine particles is preferably 80 to 180 ° C, more preferably 100 to 160 ° C. If the softening point of the resin fine particles is too high, it may be difficult to fix the toner well at a low temperature. If the softening point of the resin fine particles covering the core particles is too low, the heat resistant storage stability of the toner may be impaired. On the other hand, if the softening point of the resin fine particles covering the core particles is too low, the crushing strength of the toner at 25 ° C. tends to be less than 20 MPa. The softening point of the resin fine particles covering the core particle can be measured by a method similar to the method for measuring the softening point of the binder resin.

  The glass transition point (Tg) of the resin fine particles covering the core particles is not particularly limited as long as the toner in which the core particles are coated with the resin fine particles has a predetermined Young's modulus and crushing strength. Typically, the Tg of the resin fine particles covering the core particles is preferably 45 to 80 ° C, and more preferably 55 to 70 ° C. If the Tg of the resin fine particles covering the core particles is too low, toner particles may aggregate in a high temperature and high humidity environment. On the other hand, if the Tg of the resin fine particles is too low, the crushing strength of the toner at 25 ° C. tends to be below 20 MPa. If the Tg of the resin fine particles covering the core particles is too high, it may be difficult to fix the toner well at a low temperature. The glass transition point of the resin fine particles can be measured by the same method as the method for measuring the glass transition point of the binder resin.

  The number average molecular weight (Mn) of the resin constituting the resin fine particles covering the core particles is not particularly limited as long as the toner in which the core particles are coated with the resin fine particles has a predetermined Young's modulus and crushing strength. Typically, the number average molecular weight (Mn) of the resin constituting the resin fine particles covering the core particles is preferably 3,000 to 1,000,000, and more preferably 5,000 to 500,000. The molecular weight distribution (Mw / Mn) represented by the ratio between the number average molecular weight (Mn) and the mass average molecular weight (Mw) is preferably 2 to 30, and more preferably 3 to 10. The number average molecular weight (Mn) and the mass average molecular weight (Mw) of the resin constituting the resin fine particles can be measured by gel permeation chromatography.

  The resin fine particles that coat the core particles used in the present invention are selected from the group consisting of (meth) acrylic resins and styrene- (meth) acrylic resins, since the resin fine particles having the above physical properties are easily obtained. Resin fine particles composed of one or more resins are preferred. Further, even under high humidity conditions, it is easy to suppress a decrease in toner charge amount due to the influence of humidity, and it is easy to suppress the occurrence of fogging in the formed image. Hereinafter, the (meth) acrylic resin and the styrene- (meth) acrylic resin will be described in order.

[(Meth) acrylic resin]
The (meth) acrylic resin is a resin obtained by copolymerizing at least a monomer containing a (meth) acrylic monomer. The content of the unit derived from the (meth) acrylic monomer contained in the (meth) acrylic resin is not particularly limited as long as the object of the present invention is not impaired, but is preferably 70% by mass or more, and 80% by mass or more. Is more preferably 90% by mass or more, and most preferably 100% by mass.

  (Meth) acrylic monomers used for the preparation of (meth) acrylic resins include (meth) acrylic acid; alkyl (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. ) Acrylates; (meth) acrylamides such as (meth) acrylamides, N-alkyl (meth) acrylamides, N-aryl (meth) acrylamides, N, N-dialkyl (meth) acrylamides, and N, N-diaryl (meth) acrylamides Compounds. Moreover, it is preferable that (meth) acrylic-type resin contains the carboxyl group contained in the unit derived from (meth) acrylic acid as an acidic group. In this case, the acid value of the (meth) acrylic resin can be adjusted by increasing or decreasing the amount of (meth) acrylic acid used when preparing the (meth) acrylic resin.

  When the (meth) acrylic resin is a resin obtained by copolymerizing other monomers other than the (meth) acrylic monomer, the other monomers include ethylene, propylene, butene-1, pentene-1, hexene-1, Olefins such as heptene-1 and octene-1; allyl esters such as allyl acetate, allyl benzoate, allyl acetoacetate, and allyl lactate; hexyl vinyl ether, octyl vinyl ether, ethylhexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, Chlorethyl vinyl ether, 2-ethylbutyl vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, benzyl vinyl ether, vinyl phenyl ether, vinyl tolyl ether, vinyl chloride Vinyl ethers such as nil ether, vinyl-2,4-dichlorophenyl ether, and vinyl naphthyl ether; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl diethyl acetate, vinyl chloroacetate, vinyl methoxyacetate, Examples thereof include vinyl esters such as vinyl butoxy acetate, vinyl phenyl acetate, vinyl acetoacetate, vinyl lactate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, and vinyl naphthoate.

[Styrene- (meth) acrylic resin]
The styrene- (meth) acrylic resin is a resin obtained by copolymerizing at least a monomer containing a styrene monomer and a (meth) acrylic monomer. The total content of the units derived from the styrene monomer and the unit derived from the (meth) acrylic monomer contained in the styrene- (meth) acrylic resin is not particularly limited as long as the object of the present invention is not impaired. However, 70 mass% or more is preferable, 80 mass% or more is more preferable, 90 mass% or more is especially preferable, and it is most preferable that it is 100 mass%.

  Styrene monomers used for the preparation of styrene- (meth) acrylic resins include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2, Examples include 4-dimethylstyrene, pn-butylstyrene, p-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, and p-chlorostyrene.

  The (meth) acrylic monomer used for the preparation of the styrene- (meth) acrylic resin is the same as the (meth) acrylic monomer used for the preparation of the (meth) acrylic resin.

  Moreover, it is preferable that styrene- (meth) acrylic-type resin contains the carboxyl group contained in the unit derived from (meth) acrylic acid as an acidic group. In this case, the acid value of the styrene- (meth) acrylic resin can be adjusted by increasing or decreasing the amount of (meth) acrylic acid used when preparing the styrene- (meth) acrylic resin.

  In the case where the styrene- (meth) acrylic resin is a resin obtained by copolymerizing a styrene monomer and another monomer other than the (meth) acrylic monomer, examples of the other monomer are those in the (meth) acrylic resin. The same as other monomers other than the (meth) acrylic monomer.

  The amount of resin fine particles used is not particularly limited as long as the object of the present invention is not impaired. Specifically, 5 to 15 parts by mass is preferable with respect to 100 parts by mass of the binder resin contained in the core particles.

The resin fine particles used for coating the core particles have a storage elastic modulus measured according to the above method of 100 ° C., 2.5 × 10 ^{5 to} 2.0 × 10 ⁶ Pa, and 150 ° C. 6.0 × 10 ^{2 to} 2.0 × 10 ⁴ Pa. By using resin fine particles having a storage elastic modulus in this range as a material for coating the core particles, a toner capable of suppressing the adhesion of the toner to the developing sleeve can be obtained.

≪Toner production method≫
When the toner of the present invention is composed of core particles and resin fine particles that coat the core particles, the toner of the present invention can coat the aforementioned core particles with the aforementioned resin fine particles by various known methods. Is obtained.

  The method of coating the core particles with resin fine particles is not particularly limited as long as a toner having a predetermined Young's modulus and crushing strength is obtained, and may be a dry method or a wet method.

  In the dry method, resin fine particles are supplied to the agitated dry core particles, and the resin fine particles are adhered to the surface of the core particles. In this case, the dry core particles are preferably dispersed in the gas phase. The resin fine particles may be supplied in any state of a dried powder or a suspension in an aqueous medium.

  In the wet method, resin fine particles are added to a suspension in which core particles are dispersed in an aqueous medium, and the suspension containing the core particles and resin fine particles is stirred to attach the resin fine particles to the surface of the core particles. It is a method to make it. When the suspension containing the core particles and the resin fine particles is stirred, it is preferably heated.

  Hereinafter, a preferred method among the wet methods is a method in which resin fine particles are added to a suspension containing the core particles obtained by the above-described aggregation method in an aqueous medium, and the core particles are coated with the resin fine particles. Will be described.

  First, resin fine particles are added to a suspension containing core particles obtained by the aggregation method in an aqueous medium. The resin fine particles may be a powder in a dry state, and may be, for example, a suspension of resin fine particles in an aqueous medium obtained by an emulsion polymerization method. Since the resin fine particles are rapidly dispersed in the suspension containing the core particles in the aqueous medium, the resin fine particles are preferably used as a suspension of the resin fine particles in the aqueous medium.

  After mixing the core particles and the resin fine particles in the aqueous medium, it is preferable to stir the suspension containing the core particles and the resin fine particles while heating. The temperature at which the suspension containing the core particles and the resin fine particles is heated is not particularly limited as long as the object of the present invention is not impaired. Typically, the suspension containing the core particles and the resin fine particles is preferably heated to a temperature not lower than the glass transition point of the resin fine particles and not higher than the melting point of the resin fine particles used as the binder resin for the core particles. By heating the suspension to a temperature in such a range, it is easy to prepare a toner having a uniform shape. In this way, the surface of the core particle is coated with the resin fine particles to be a toner.

  The toner thus obtained is recovered from the suspension by filtration and then washed with water as necessary. The filtered toner is dried under conditions such that the toner does not aggregate or deform due to heat.

  The toner thus obtained may have an external additive attached to the surface thereof as necessary. In the specification and claims of the present application, the particles before being treated with the external additive may be described as toner mother particles.

  The type of external additive is not particularly limited as long as it does not impair the object of the present invention, and can be appropriately selected from external additives conventionally used for toners. Specific examples of suitable external additives include metal oxides such as silica, alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, and barium titanate. These external additives can be used in combination of two or more. These external additives can also be used after being hydrophobized with a hydrophobizing agent such as an aminosilane coupling agent or silicone oil. In the case of using a hydrophobized external additive, it is easy to suppress a decrease in charge amount of the toner under high temperature and high humidity, and it is easy to obtain a toner excellent in fluidity.

  The particle diameter of the external additive is not particularly limited as long as the object of the present invention is not impaired, and typically 0.01 to 1.0 μm is preferable.

  The amount of the external additive used is not particularly limited as long as the object of the present invention is not impaired. The amount of the external additive used is typically preferably 1 to 10 parts by mass, more preferably 2 to 5 parts by mass with respect to 100 parts by mass of the toner base particles.

  The method for attaching the external additive to the surface of the toner base particles is not particularly limited, and can be appropriately selected from conventionally known methods. Specifically, the processing conditions are adjusted so that the particles of the external additive are not embedded in the toner base particles, and the processing with the external additive is performed by a mixer such as a Henschel mixer or a Nauter mixer.

  The toner of the present invention described above has a Young's modulus at 25 ° C. of 100 to 150 MPa, and a crushing strength at 25 ° C. of 20 MPa or more. The Young's modulus and crushing strength of the obtained toner can be confirmed by the following methods.

<Measurement method of Young's modulus and crushing strength>
The Young's modulus and crushing strength of the toner are measured using a micro-compression tester (MCT-211 (manufactured by Shimadzu Corporation)) at 25 ° C. The toner particles used as the evaluation object are preferably toner particles having a particle diameter corresponding to the median diameter of the toner particle size distribution. The toner particles are pressurized to 9.8 mN with a flat thickness (50 μm diameter) at an applied speed of 0.284 mN / s, and the stress (mN) and displacement (μm) at that time are measured. Get the displacement curve. The crushing strength can be calculated by the following formula from the stress and the particle diameter when the stress becomes constant in the stress-displacement curve. The Young's modulus can be calculated from the relationship between the stress and displacement until the stress becomes constant and the particle diameter in the stress-displacement curve by the following equation. In the following formula, the stress is P (mN), the particle diameter is D (μm), and the compression displacement is ΔD (μm).
(Crushing strength)
Crushing strength (MPa) = 2.8 × P / (π × D × D)
(Young's modulus)
Young's modulus (MPa) = 1000 × (P / (π × (D / 2) × (D / 2))) / (ΔD / D)

  The toner of the present invention having a Young's modulus at 25 ° C. of 100 to 150 MPa and a crushing strength at 25 ° C. of 20 MPa or more is excellent in heat-resistant storage and low-temperature fixability, and generates offset at high temperature. It is possible to suppress this, and it is excellent in releasability between the fixing roller and the recording medium on which the image is formed, and it is possible to suppress image defects due to toner adhesion to the developing sleeve and image defects such as fogging in the formed image. For this reason, the electrostatic image developing toner produced by the method of the present invention is suitably used in various image forming apparatuses.

<SP value>
In the toner of the present invention, the difference in SP value (ΔSP) between the resin used for the core particle of the toner and the resin used for coating the core particle with respect to the solubility parameter (hereinafter also simply referred to as SP value). ) Is preferably 1.8 to 2.4. When the SP value of the resin used for the core particle of the toner and the SP value of the resin used for coating the core particle are within such ranges, there is a clear interface between the shell layer and the core layer. It is easy to obtain a toner having excellent crushing strength. The SP value is a value represented by the square root of the molecular cohesive energy. F. It can be calculated by the method described in Fedors, Polymer Engineering Science, 14, p147 (1974). The unit is (MPa) ^1/2 and indicates a value at 25 ° C.

  The toner of the present invention described above can be mixed with a desired carrier and used as a two-component developer. Hereinafter, the two-component developer will be described.

≪Two-component developer≫
When preparing a two-component developer, it is preferable to use a magnetic carrier as the carrier. Suitable carriers include those in which a carrier core material is coated with a resin. Specific examples of carrier core materials include particles of iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, cobalt, etc., and particles of alloys of these materials with manganese, zinc, aluminum, etc. , Particles such as iron-nickel alloy, iron-cobalt alloy, titanium oxide, aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, barium titanate, lithium titanate, lead titanate , Ceramic particles such as lead zirconate and lithium niobate, particles of high dielectric constant materials such as ammonium dihydrogen phosphate, potassium dihydrogen phosphate, and Rochelle salt, resin carriers in which the above magnetic particles are dispersed in a resin, etc. Is mentioned.

  Specific examples of the resin covering the carrier core material include (meth) acrylic polymers, styrene polymers, styrene- (meth) acrylic copolymers, olefin polymers (polyethylene, chlorinated polyethylene, polypropylene, etc. ), Polyvinyl chloride, polyvinyl acetate, polycarbonate, cellulose resin, polyester resin, unsaturated polyester resin, polyamide resin, polyurethane resin, epoxy resin, silicone resin, fluororesin (polytetrafluoroethylene, polychlorotrifluoroethylene, polyfluoride) Vinylidene chloride, etc.), phenol resin, xylene resin, diallyl phthalate resin, polyacetal resin, amino resin and the like. These resins can be used in combination of two or more.

  The particle diameter of the carrier is not particularly limited as long as the object of the present invention is not impaired, but is preferably 20 to 120 μm, more preferably 25 to 80 μm, as measured by an electron microscope.

  When the electrostatic charge image developing toner of the present invention is used as a two-component developer, the toner content is preferably 3 to 20% by mass, more preferably 5 to 15% by mass, based on the mass of the two-component developer. By setting the toner content in the two-component developer within such a range, an appropriate image density is maintained in the formed image, and toner inside the image forming apparatus or toner on transfer paper is suppressed by suppressing toner scattering from the developing apparatus. Can be suppressed.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited at all by the Example.

[Preparation Example 1]
According to the following method, resin fine particle dispersions A to C used as a binder resin in the formation of core particles were prepared.

(Preparation of resin fine particle dispersion A)
According to the following method, the dispersion liquid in the aqueous medium of the resin fine particle which is the polyester resin a was prepared.

A polyester resin a having the following physical properties was used as a binder resin. Moreover, the storage elastic modulus of the polyester resin a was 1.5 × 10 ¹ Pa at 100 ° C. and 1.2 Pa at 150 ° C.
Number average molecular weight (Mn): 1200
Mass average molecular weight (Mw): 2300
Molecular weight distribution (Mw / Mn): 1.92
Melting temperature (Tm): 70.8 ° C
Glass transition point (Tg): 38.4 ° C
Acid value: 11.6 mg KOH / g
SP value: 11.3
In addition, the number average molecular weight (Mn) and the mass average molecular weight (Mw) of the said resin were measured on condition of the following using gel permeation chromatography (GPC). Further, the acid value (mgKOH / g) of the resin was confirmed by titration.

<GPC measurement conditions>
GPC device: HLC-8020 GPC (manufactured by Tosoh Corporation)
Column: TSKgel, Super Multipore HZ-H (manufactured by Tosoh Corporation, 4.6 mm ID × 15 cm)
Number of columns: 3 Eluent: Tetrahydrofuran Flow rate: 0.35 ml / min Sample injection volume: 10 μl
Measurement temperature: 40 ° C
Detector: IR detector calibration curves are F-40, F-20, F-4, F-1, A-5000, A-2500, A from standard samples (TSK standard, polystyrene, manufactured by Tosoh Corporation). -1000 and 8 types of n-propylbenzene were selected and prepared.

  100 parts by mass of coarsely pulverized polyester resin a having an average particle diameter of about 10 μm obtained by coarsely pulverizing polyester resin a with Turbo Mill T250 (manufactured by Turbo Industry Co., Ltd.), A 0.1N sodium hydroxide aqueous solution (basic substance) (50 parts by mass) was mixed, and ion-exchanged water was further added as an aqueous medium to prepare a slurry having a total amount of 500 parts by mass. The obtained slurry was put into a pressure-resistant round bottom stainless steel container, and the slurry was 145 ° C., pressure 0.5 MPa (G) using a high-speed shearing emulsifier CLEARMIX (CLM-2.2S (manufactured by M Technique)). In the state of heating and pressurizing, the rotor was rotated at 20000 rpm for 30 minutes for shear dispersion. Thereafter, stirring is continued at a rotor rotational speed of 15000 rpm until the internal temperature of the stainless steel container reaches 50 ° C. After cooling the slurry at a rate of 5 ° C./min, ion-exchanged water is added so that the solid content concentration becomes 20% by mass. In addition, resin fine particle dispersion A was obtained.

(Preparation of resin fine particle dispersion B)
A resin fine particle dispersion B was obtained in the same manner as the resin fine particle dispersion A, except that the polyester resin b having the following physical properties was used instead of the polyester resin a. Further, the storage elastic modulus of the polyester resin b was 3.3 × 10 ¹ Pa at 100 ° C. and 2.8 Pa at 150 ° C.
Number average molecular weight (Mn): 1500
Mass average molecular weight (Mw): 3100
Molecular weight distribution (Mw / Mn): 2.07
Melting temperature (Tm): 80.4 ° C
Glass transition point (Tg): 46.0 ° C
Acid value: 10.9mgKOH / g
SP value: 11.0

(Preparation of resin fine particle dispersion C)
A resin fine particle dispersion C was obtained in the same manner as the resin fine particle dispersion A, except that the polyester resin c having the following physical properties was used instead of the polyester resin a. Further, the storage elastic modulus of the polyester resin c was 2.7 × 10 ² Pa at 100 ° C. and 5.7 Pa at 150 ° C.
Number average molecular weight (Mn): 1400
Mass average molecular weight (Mw): 3300
Molecular weight distribution (Mw / Mn): 2.36
Melting temperature (Tm): 90.3 ° C
Glass transition point (Tg): 52.3 ° C.
Acid value: 12.1 mgKOH / g
SP value: 11.1

[Preparation Example 2]
Resin fine particle dispersions D to F used for coating the core particles were prepared according to the following method.

(Preparation of resin fine particle dispersion D)
A resin fine particle dispersion D was obtained in the same manner as the resin fine particle dispersion A except that an acrylic resin d having the following physical properties was used instead of the polyester resin a. Further, the storage elastic modulus of the acrylic resin d was 1.3 × 10 ⁶ Pa at 100 ° C. and 1.2 × 10 ⁴ Pa at 150 ° C.
Number average molecular weight (Mn): 34,000
Mass average molecular weight (Mw): 87,000
Molecular weight distribution (Mw / Mn): 6.70
Melting temperature (Tm): 147.9 ° C
Glass transition point (Tg): 62.9 ° C
SP value: 9.2

(Preparation of resin fine particle dispersion E)
A resin fine particle dispersion E was obtained in the same manner as the resin fine particle dispersion A except that an acrylic resin e having the following physical properties was used instead of the polyester resin a. Moreover, the storage elastic modulus of the acrylic resin e was 4.3 × 10 ⁵ Pa at 100 ° C. and 6.7 × 10 ² Pa at 150 ° C.
Number average molecular weight (Mn): 29,000
Mass average molecular weight (Mw): 90,000
Molecular weight distribution (Mw / Mn): 3.10
Melting temperature (Tm): 123.4 ° C
Glass transition point (Tg): 63.0 ° C
SP value: 8.9

(Preparation of resin fine particle dispersion F)
A resin fine particle dispersion F was obtained in the same manner as the resin fine particle dispersion A, except that an acrylic resin f having the following physical properties was used instead of the polyester resin a. Moreover, the storage elastic modulus of the acrylic resin f was 8.2 × 10 ⁴ Pa at 100 ° C. and 9.5 × 10 ¹ Pa at 150 ° C.
Number average molecular weight (Mn): 5000
Mass average molecular weight (Mw): 15,000
Molecular weight distribution (Mw / Mn): 6.70
Melting temperature (Tm): 117.4 ° C
Glass transition point (Tg): 63.1 ° C.
SP value: 10.6

[Preparation Example 3]
(Preparation of colorant fine particle dispersion)
As a colorant, 60 parts by mass of carbon black (MA-100 (manufactured by Mitsubishi Chemical Corporation)), 2 parts by mass of an anionic surfactant (Emar E27C (manufactured by Kao Corporation)), and 340 parts by mass of ion-exchanged water are mixed. The mixture was emulsified using a homogenizer (Ultra Turrax T50 (manufactured by IKA)) to obtain a colorant fine particle dispersion having a solid content concentration of 15% by mass.

[Preparation Example 4]
(Preparation of release agent fine particle dispersion)
Release agent (WEP-5, pentaerythritol behenic acid ester wax, melting temperature 84 ° C. (manufactured by NOF Corporation)) 200 parts by mass, anionic surfactant (Emar E27C (manufactured by Kao Corporation)) 2 parts by mass, And 800 parts by mass of ion-exchanged water were mixed, heated to 100 ° C. to melt the release agent, and then emulsified with a homogenizer (Ultra Turrax T50 (manufactured by IKA)) for 5 minutes. Subsequently, the emulsification treatment was performed again at a temperature of 100 ° C. and a discharge pressure of 100 MPa using a high-pressure homogenizer (Nanomizer NV-200 (manufactured by Yoshida Kikai Co., Ltd.)). In the high-pressure homogenizer, the plunger diameter of the pressure head was 10 mm, and a 120-micron through-type nozzle was used as the generator. In this way, a dispersion of release agent fine particles having an average particle diameter of 250 nm, a melting point (Tm) of 83 ° C., and a solid content concentration of 20% by mass was obtained.

[Preparation Example 5]
(Preparation of silica)
100 g of dimethylpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 100 g of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) were dissolved in 200 g of toluene, and then diluted 10 times. Next, while stirring 200 g of fumed silica Aerosil # 90 (manufactured by Nippon Aerosil Co., Ltd.), a diluted solution of dimethylpolysiloxane and 3-aminopropyltrimethoxylane was gradually added dropwise, followed by ultrasonic irradiation and stirring for 30 minutes. And mixed. The obtained mixture was heated in a constant temperature bath at 150 ° C., and then toluene was distilled off with a rotary evaporator to obtain a solid. The obtained solid was dried with a vacuum dryer at a set temperature of 50 ° C. until it was not reduced. Furthermore, it was treated at 200 ° C. for 3 hours in a nitrogen stream in an electric furnace to obtain a coarse silica powder. The silica coarse powder was pulverized by a jet mill (IDS type jet mill (manufactured by Nippon Pneumatic Industry Co., Ltd.)) and collected by a bag filter to obtain silica.

[Example 1]
In a 2 L round bottom flask made of stainless steel, 500 g of resin fine particle dispersion A, 68 g of release agent fine particle dispersion, and 33 g of colorant fine particle dispersion were placed and mixed at 25 ° C. Next, 1 g of 1N sodium hydroxide aqueous solution was added to the flask while the inside of the flask was stirred at a speed of 100 rpm with a stirring blade, and the pH was adjusted to 11. Thereafter, the contents of the flask were stirred at 25 ° C. for 10 minutes, and then 17 g of a flocculant (mixed solution of magnesium chloride and water, magnesium chloride content 50 mass%) was added to the flask over 5 minutes. After the flocculant was added, the temperature in the flask was increased to 50 ° C. at a rate of temperature increase of 0.2 ° C./min, and the temperature of the flask measured with a particle size meter (Multisizer 3 (Beckman Coulter, Inc.)) at the same temperature. The contents of the flask were stirred until the volume average particle diameter of the aggregated particles of the contents became 5.0 μm. Thereafter, the speed of the stirring blade is set to 200 rpm, the temperature in the flask is increased to 55 ° C. at a rate of temperature increase of 0.2 ° C./min, and the contents of the flask are stirred at the same temperature for 60 minutes. A dispersion was obtained. The average circularity of the core particles measured by FPIA3000 (manufactured by Sysmec Corporation) was 0.940.

  Next, 50 g of the resin fine particle dispersion D is put into a flask container containing the core particle dispersion, and the temperature in the flask is increased to 70 ° C. at a temperature increase rate of 0.2 ° C./min. After stirring the contents of the flask for 120 minutes at a rotation speed of 133 rpm, 50 g of a flocculant (aqueous sodium chloride solution having a concentration of 20% by mass) was added. Thereafter, the temperature in the flask was increased to 80 ° C. at a rate of temperature increase of 0.2 ° C./min, and the contents of the flask were stirred at the same temperature for 120 minutes. Thereafter, the mixture was cooled to 25 ° C. at 10 ° C./min to obtain a dispersion of toner mother particles.

  The toner base particle wet cake was filtered off from the toner base particle dispersion by suction filtration, and then the wet cake was dispersed again in ion-exchanged water to wash the toner base particles. The same operation was repeated, and the toner base particle wet cake recovered after the toner base particles were washed five times was dried in the next step.

A wet cake of toner base particles was dispersed in an aqueous ethanol solution having a concentration of 50% by mass to prepare a slurry. The obtained slurry was dried by a continuous surface reformer (Coat Mizer (Freund Sangyo Co., Ltd.)) to obtain toner base particles. The drying conditions with the coatizer were a hot air temperature of 40 ° C. for 72 hours and a blower air volume of 2 m ³ / min. The volume average particle diameter of the toner measured with a particle size meter (Multisizer 3 (manufactured by Beckman Coulter, Inc.)) was 5.6 μm. Further, the average circularity of the toner base particles as measured by FPIA 3000 (manufactured by Sysmec Corporation) was 0.974.

  100 parts by mass of the obtained toner base particles and 2 parts by mass of silica were mixed with a Henschel mixer (Mitsui Miike Kogyo Co., Ltd., capacity 5 L), and then the mixture was sieved (# 300 mesh, mesh opening 48 μm). The toner of Example 1 was obtained.

[Example 2]
A toner of Example 2 was obtained in the same manner as in Example 1 except that the resin fine particle dispersion D was changed to the resin fine particle dispersion E.

Example 3
A toner of Example 3 was obtained in the same manner as in Example 1 except that the resin fine particle dispersion A was changed to the resin fine particle dispersion B.

Example 4
After the core particle wet cake was filtered from the core particle dispersion prepared in the same manner as in Example 1 by suction filtration, the wet cake was again dispersed in ion-exchanged water to wash the core particles. The same operation was repeated, and the wet cake of core particles recovered after washing the core particles five times was dried in the next step.

The wet cake of core particles was dispersed in an aqueous ethanol solution having a concentration of 50% by mass to prepare a slurry. The obtained slurry was dried by a continuous surface reformer (Coat Mizer (manufactured by Freund Corporation)) to obtain core particles. The drying conditions with the coatizer were a hot air temperature of 40 ° C. for 72 hours and a blower air volume of 2 m ³ / min. The volume average particle diameter of the core particles measured by a particle size meter (Multisizer 3 (manufactured by Beckman Coulter, Inc.)) was 5.0 μm. Further, the average circularity of the core particles measured by FPIA3000 (manufactured by Sysmec Corporation) was 0.940.

Using a 10 L fine particle coating apparatus (SFP-01 manufactured by Paulec), 40 ml of the resin fine particle dispersion E was sprayed from a spray nozzle onto 100 g of the toner core particles. When spraying the spray liquid, compressed air of 25 nl / min is sent to the spray nozzle, spraying the spray liquid at a pace of 5.0 ml / min, and ventilating air at 80 ° C. at a pace of 0.5 m ³ / min. From the part, it was fed into the fluidized bed container. The peripheral speed of the first stirring blade was rotated at 0.75 m / s, and the gap between the first stirring blade and the mesh screen was set to 0.5 mm. A mesh screen having a thickness of 1 mm, an aperture ratio of 50%, and a hole diameter of 1 mm was used. After 8 minutes, the toner base particles were taken out from the fine particle coating apparatus for which the supply of the spray liquid was completed. Toner mother particles having a volume average particle diameter of 5.19 μm and an average circularity of 0.982 were obtained.

  100 parts by mass of the obtained toner base particles and 2 parts by mass of silica were mixed with a Henschel mixer (Mitsui Miike Kogyo Co., Ltd., capacity 5 L), and then the mixture was sieved (# 300 mesh, mesh opening 48 μm). The toner of Example 4 was obtained.

[Comparative Example 1]
Core particles were prepared in the same manner as in Example 4. Using the obtained core particles as toner base particles, the toner base particles were treated with an external additive in the same manner as in Example 1 to obtain the toner of Comparative Example 1.

[Comparative Example 2]
A toner of Comparative Example 2 was obtained in the same manner as in Example 1 except that the resin fine particle dispersion A was changed to the resin fine particle dispersion C.

[Comparative Example 3]
A toner of Comparative Example 3 was obtained in the same manner as in Example 1 except that the resin fine particle dispersion D was changed to the resin fine particle dispersion F.

  For the toners obtained in Examples 1 to 4 and Comparative Examples 1 to 3, Young's modulus and crushing strength were measured according to the following methods. Tables 1 and 2 show the Young's modulus and crushing strength of the toners of Examples 1 to 4 and Comparative Examples 1 to 3, respectively.

<Measurement method of Young's modulus and crushing strength>
The Young's modulus and crushing strength of the toner were measured using a micro-compression tester (MCT-211 (manufactured by Shimadzu Corporation)) at 25 ° C. As the toner particles used as evaluation targets, toner particles having a particle diameter corresponding to the median diameter of the toner particle diameter distribution were used. The toner particles are pressurized to 9.8 mN with a flat thickness (50 μm diameter) at an applied speed of 0.284 mN / s, and the stress (mN) and displacement (μm) at that time are measured. A displacement curve was obtained. The crushing strength was calculated by the following formula from the stress and particle diameter when the stress became constant in the stress-displacement curve. The Young's modulus was calculated by the following equation from the relationship between stress and displacement until the stress became constant and the particle diameter in the stress-displacement curve. In the following formula, the stress is P (mN), the particle diameter is D (μm), and the compression displacement is ΔD (μm).
(Crushing strength)
Crushing strength (MPa) = 2.8 × P / (π × D × D)
(Young's modulus)
Young's modulus (MPa) = 1000 × (P / (π × (D / 2) × (D / 2))) / (ΔD / D)

  Moreover, the heat resistant storage stability was evaluated according to the following method using the toners obtained in Examples 1 to 4 and Comparative Examples 1 to 3. Tables 1 and 2 show the evaluation results of the heat resistant storage stability of the toners of Examples 1 to 4 and Comparative Examples 1 to 3.

≪Method for evaluating heat-resistant storage stability≫
3 g of toner is weighed in a 20 ml capacity plastic container, left in a thermostat set at 60 ° C. for 3 hours, and then left in an environment of 25 ° C. and 65% RH for 30 minutes to evaluate heat resistant storage stability. No toner was obtained. Thereafter, sieves having openings of 105 μm, 63 μm, and 45 μm are used in an overlapping manner in order from the smallest openings, and a toner for heat-resistant storage stability evaluation is placed on the sieve having openings of 105 μm, and a powder tester (Hosokawa Micron Corporation) is used. The product was screened for 30 seconds using the vibration scale 5. After sieving, the mass of the toner remaining on the sieve having an opening of 105 μm (T ₁ (g)), the mass of the toner remaining on the 63 μm sieve (T ₂ (g)), and the toner remaining on the 45 μm sieve Each mass (T ₃ (g)) was weighed, and the degree of aggregation of the toner was measured by the following formula.
_{T 1/3 × 100 = C} 1
_{T 2/3 × 100 × 3} /5 = C 2
_{T 3/3 × 100 × 1} /5 = C 3
Toner cohesion (%) = C ₁ + C ₂ + C ₃
Evaluation of heat-resistant storage stability was evaluated according to the following criteria, and evaluations of “◯” and “Δ” were accepted, and evaluation of “x” was rejected.
○: The degree of aggregation of the toner is less than 2%.
Δ: The degree of aggregation of the toner is 2% or more and less than 15%.
X: The degree of aggregation of the toner is 15% or more.

  Further, using the toners obtained in Examples 1 to 4 and Comparative Examples 1 to 3, low temperature fixability, high temperature offset resistance, and fixing separability (separable toner loading amount) were evaluated according to the following methods. did. For evaluation of low-temperature fixing property, high-temperature offset resistance, and fixing separation property, an external driving device and a fixing temperature control device are used in a fixing device (fixing unit) of a color multifunction peripheral (TASKalfa 550ci (manufactured by Kyocera Mita Corporation)). Was used. Plain paper was used as the recording medium. The evaluation of the low-temperature fixability, the high-temperature offset resistance, and the fixing separation property was performed using a two-component developer prepared according to the following method. The evaluation results of the toners of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Tables 1 and 2.

<Preparation of two-component developer>
(Preparation of carrier)
39.7Mol% in terms of MnO, 9.9 mol% in terms of MgO, 49.6Mol% in terms _{of Fe} 2 _{O 3,} each raw material was adequate amount to be 0.8 mol% in terms of SrO, water was added, wet The mixture was pulverized and mixed with a ball mill for 10 hours. The resulting mixture was dried and then kept at 950 ° C. for 4 hours. Next, the mixture was pulverized with a wet ball mill for 24 hours to prepare a slurry. After granulating and drying the slurry, the granulated product is held at 1270 ° C. for 6 hours in an atmosphere having an oxygen concentration of 2%, and then crushed and adjusted in particle size to obtain manganese-based ferrite particles (carrier core material). It was. The obtained manganese-based ferrite particles had an average particle diameter of 35 μm and a saturation magnetization of 70 Am ² / kg when the applied magnetic field was 3000 (103 / 4π · A / m).

  Next, a polyamideimide resin (copolymer of trimellitic anhydride and 4,4′-diaminodiphenylmethane) is diluted with methyl ethyl ketone to prepare a resin solution, and then a tetrafluoroethylene / hexafluoropropylene copolymer (FEP) and silicon oxide (2% by mass of the total amount of the resin) were dispersed in the resin solution to obtain a carrier coat solution in an amount of 150 g in terms of solid content. The mass ratio of polyamideimide resin and FEP was 2/8 as polyamideimide resin / FEP, and the solid content ratio of the resin solution was 10 mass%.

  Using the obtained carrier coat solution, 10 kg of manganese-based ferrite particles were coated with a fluidized bed coating apparatus (Spiracoater SP-25 (Okada Seiko Co., Ltd.)). Thereafter, the manganese-based ferrite particles coated with the resin were fired at 220 ° C. for 1 hour to obtain a resin-coated ferrite carrier having a resin coating amount of 3 mass%.

(Mixing of toner and carrier)
The obtained resin-coated ferrite carrier and the toners of Examples 1 to 4 and Comparative Examples 1 to 3 were mixed so that the toner concentration in the two-component developer was 10% by mass, and the two-component developer Was prepared.

≪Evaluation method of low-temperature fixability≫
An unfixed solid image having a size of 2 cm × 3 cm and a toner amount of 1.8 g / cm ² was formed by a color composite machine. The obtained unfixed image was fixed by a fixing tester set at a predetermined temperature under a condition of a linear speed of 97 mm / second. The image after fixing was folded in half so that the image portion was inside, and the bottom surface was rubbed 5 times on the crease with a 1 kg weight covered with a fabric. Next, the paper was spread and the image portion was rubbed 5 times with a weight. Images with toner peeling of 1 mm or less at the bent portion were evaluated according to the following criteria. It was judged as “good”, and over 1 mm was judged as “x”. Evaluation is performed by changing the fixing temperature in increments of 5 ° C., and the lowest fixing temperature at which toner peeling is determined to be ○ is set as the minimum fixing temperature, and the low-temperature fixing property is evaluated according to the following criteria. The evaluation was passed and the evaluation of x was rejected.
○: The minimum fixing temperature is less than 100 ° C.
(Triangle | delta): The minimum fixing temperature is 100 degreeC or more and less than 115 degreeC.
X: The minimum fixing temperature is 115 ° C. or higher.

≪High temperature offset resistance evaluation method≫
An unfixed solid image having a size of 2 cm × 3 cm and a toner amount of 1.8 g / cm ² was formed by a color composite machine. The obtained unfixed image was fixed by a fixing tester set at a predetermined temperature under a linear speed of 49 mm / sec. Evaluate by changing the fixing temperature in increments of 5 ° C. Assume that the highest fixing temperature at which no offset occurs is the highest high temperature resistant offset temperature, evaluate high temperature offset resistance according to the following criteria, and evaluate ○ and △. A pass or an evaluation of x was regarded as a failure.
○: Maximum high temperature resistant offset temperature is 140 ° C. or higher.
(Triangle | delta): Maximum high temperature-resistant offset temperature is 115 degreeC or more and less than 140 degreeC.
X: Maximum high temperature resistant offset temperature is less than 115 ° C.

≪Evaluation method for fixing separability (separable toner load) ≫
Using a color compound machine, obtain a solid unfixed image with a tip margin of 3 mm, and measure the unfixed image at a fixing temperature of 180 ° C. and a linear speed of 97 mm / sec while measuring the amount of toner on the paper. I passed. The amount of applied toner was changed in increments of 0.1 mg / cm ² , and the amount of applied toner (mg / cm ² ) at which the paper did not wrap around the fixing roller was defined as the separable amount of applied toner. The fixing separability was evaluated according to the following criteria, and evaluations of “◯” and “Δ” were accepted and “x” was rejected.
A: The amount of applied toner is 1.5 mg / cm ² or more.
Δ: Toner loading is 1.0 mg / cm ² or more and less than 1.5 mg / cm ² .
X: The amount of applied toner is less than 1.0 mg / cm ² .

  Further, using the toners obtained in Examples 1 to 4 and Comparative Examples 1 to 3, sleeve adhesion and fogging were evaluated according to the following methods. For the evaluation of sleeve adhesion and fogging, a color composite machine (TASKalfa 550ci (manufactured by Kyocera Mita Corporation)) was used, and color images were formed using four color toners. Plain paper was used as the recording medium. The evaluation results of the toners of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Tables 1 and 2.

  For the four color toners, the carbon black used in the toners of Examples 1 to 4 and Comparative Examples 1 to 3 is replaced with a yellow pigment (C.I. Pigment Yellow 180) and a cyan pigment (C.I. Pigment Blue 15- 3), or yellow toner, cyan toner, and magenta toner were obtained in the same manner as the black toner except that the pigment was changed to magenta pigment (CI Pigment Red 238). The volume average particle diameter (D50) of the yellow toner, cyan toner, and magenta toner was 6.8 μm.

≪Sleeve adhesion evaluation method≫
Using four color toners, a line pattern was continuously formed on a color composite machine in an environment of 32.5 ° C. and 60% RH under the condition of a printing rate of 20% and 10,000 sheets. After forming 10,000 images, the state of the developing sleeve was visually observed, and sleeve adhesion was evaluated according to the following criteria. Evaluation of image quality was evaluated according to the following criteria, and evaluation of ○ was passed and evaluation of × was rejected.
○: No deposits are seen on the developing sleeve.
X: A deposit is seen on the developing sleeve.

≪Evaluation method of fogging≫
Using four color toners, a character pattern was continuously formed on 5000 sheets on a color compound machine in an environment of 32.5 ° C. and 60% RH under the condition of a printing rate of 2%. Thereafter, a solid patch pattern was continuously formed on another 1000 sheets under the condition of a printing rate of 50%. The fog density was determined by subtracting the image density value of the base paper (that is, the white paper before image output) from the image density value of the blank paper equivalent measured by the reflection densitometer in 1000 patch patterns. Then, the fog density was measured every predetermined number of sheets, and the fog was evaluated based on the maximum value. The evaluation of the fog was evaluated according to the following criteria, with the evaluation of ○ being passed and the evaluation of × being rejected.
○: The maximum fog density is 0.01 or less.
X: The maximum fog density is over 0.01.

  According to Table 1, the electrostatic charge image developing toner has the surface of the core particles composed of the fine particles of the binder resin having a predetermined storage elastic modulus coated with the resin fine particles having the predetermined storage elastic modulus. The toners of Examples 1 to 4 having a Young's modulus at 25 ° C of 100 to 150 MPa and a crushing strength at 25 ° C of 20 MPa or more are excellent in heat storage stability and low-temperature fixability, and at high temperatures. Occurrence of offset, excellent releasability between the fixing roller and the recording medium on which the image is formed, and image defects due to toner adhesion to the developing sleeve and image defects such as fogging in the formed image Could be suppressed.

  On the other hand, according to Table 2, the toner of Comparative Example 1 has a Young's modulus at 25 ° C. of less than 100 MPa and a crushing strength of less than 20 MPa. In this case, it can be seen that the heat resistant storage stability of the toner cannot be obtained satisfactorily, and in the formed image, it is difficult to suppress image defects due to toner adhesion to the developing sleeve and image defects due to fogging. This is presumably because the toner of Comparative Example 1 is not coated with resin fine particles.

  Further, the toner of Comparative Example 2 has a crushing strength of 20 MPa or more at 25 ° C., but has a Young's modulus exceeding 150 MPa. In this case, it can be seen that the low-temperature fixability of the toner cannot be obtained satisfactorily. The reason why the Young's modulus exceeds 150 MPa is considered to be because a polyester resin having a relatively high melting point and glass transition point is used for the core particles. For this reason, it is considered that more energy is required to fix the toner to the recording medium, and the toner cannot be fixed satisfactorily at a low temperature.

  The toner of Comparative Example 3 has a Young's modulus of 100 to 150 MPa at 25 ° C., but a crushing strength of less than 20 MPa. In this case, it can be seen that the heat-resistant storage stability of the toner cannot be obtained satisfactorily and it is difficult to suppress image defects due to toner adhesion to the developing sleeve in the formed image. The crushing strength is less than 20 MPa because (meth) acrylic resin or styrene- (meth) acrylic resin having a relatively low melting point and glass transition point is used as the resin fine particles covering the toner core particles. This is probably because of this. For this reason, it is considered that the coating of the resin fine particles covering the toner core particles is easily broken by the stress generated in the developing machine. As a result, the heat-resistant storage stability of the toner cannot be obtained satisfactorily, and it is considered that the toner adheres to the developing sleeve.

Claims (2)

At least the surface of the core particle containing a binder resin made of a polyester resin is coated with resin fine particles made of one or more resins selected from the group consisting of (meth) acrylic resins and styrene- (meth) acrylic resins. A toner for developing an electrostatic image,
The core resin binder resin fine particles have a storage elastic modulus at 100 ° C. of 1.5 × 10 ^{1 to} 3.3 × 10 ¹ Pa and a storage elastic modulus at 150 ° C. of 1.2 to 2.8 Pa. And
The resin fine particles have a storage elastic modulus at 100 ° C. of 2.5 × 10 ^{5 to} 2.0 × 10 ⁶ Pa and a storage elastic modulus at 150 ° C. of 6.0 × 10 ^{2 to} 2.0 × 10 ⁴ Pa. And
The electrostatic image developing toner has a Young's modulus at 25 ° C. of 100 to 150 MPa and a crushing strength at 25 ° C. of 20 MPa or more. 2. The electrostatic charge image developing toner according to claim 1, wherein a difference between an SP value of the binder resin and an SP value of the resin fine particles is 1.8 to 2.4. 3.

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