JP2008145767A - Positive charge type toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive charge type toner excellent in durability. <P>SOLUTION: The positive charge type toner contains a binder resin, a release agent, a charge control agent and a colorant, wherein the binder resin contains at least a polyester, the release agent contains at least a hydrocarbon-based wax and the charge control agent contains at least a styrene-acrylic charge control resin, the toner is obtained by a method including a pulverization process, and a total content A (wt.%) of the hydrocarbon-based wax in the toner and an average circularity B of the toner satisfy the formula (I): 0.1≤A≤4 and the formula (II): 0.005A+0.925≤B≤-0.005A+0.965. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a positively chargeable toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

Conventionally, as a technique for improving the fluidity of an electrophotographic toner, there is a technique focusing on the pulverized shape of the toner. For example, Patent Document 1 discloses a toner that defines a specific particle size and circularity.
JP 2005-215148 A

  The toner having the circularity specified in Patent Document 1 can suppress fusion to the layer thickness regulating blade, but is liable to adhere to the charging blade having a large contact pressure to the toner, and is inferior in durability.

  An object of the present invention is to provide a positively chargeable toner having excellent durability.

The present invention relates to a positively chargeable toner comprising a binder resin, a release agent, a charge control agent and a colorant, wherein the binder resin is polyester, the release agent is a hydrocarbon wax, and the charge The control agent contains at least a styrene acrylic charge control resin, and is obtained by a method including a pulverization step. The total content A (% by weight) of hydrocarbon wax in the toner and the average circularity B of the toner are The following formulas (I) and (II):
0.1 ≦ A ≦ 4 (I)
0.005A + 0.925 ≦ B ≦ -0.005A + 0.965 (II)
The present invention relates to a positively chargeable toner that satisfies the following conditions.

  The toner of the present invention can prevent the toner from adhering to the charging blade and has an excellent durability.

  The toner of the present invention is a positively chargeable toner containing a binder resin, a release agent, a charge control agent and a colorant, wherein the binder resin is polyester, and the release agent is hydrocarbon wax. One feature is that the charge control agent contains at least a styrene acrylic charge control resin.

  Usually, when polyester is used for the binder resin, a styrene acrylic charge control resin is not used from the viewpoint of compatibility. However, in the present invention, a toner having excellent durability can be obtained by combining a specific amount of hydrocarbon wax with a combination of polyester and styrene acrylic charge control resin.

  The detailed reason will be described below. The hydrocarbon wax is relatively difficult to disperse in the polyester resin, but relatively easy to disperse in the styrene acrylic resin. Usually, when the toner is pulverized, it is expected that the toner is cracked at the interface between the wax and the binder resin or at the interface between resins having poor compatibility. However, in the present invention, since a hydrocarbon wax that is relatively compatible with the styrene acrylic resin is added, the wax is dispersed in the charge control resin. It becomes easy to break at the interface with polyester. Along with this, it is estimated that the wax and the charge control resin are easily exposed on the toner surface, and as a result, the chargeability is improved and the durability is excellent.

  Further, the toner of the present invention has one characteristic with respect to the shape of the toner. Usually, it is expected that the toner fluidity is improved and the durability is improved by increasing the toner circularity by a mechanical device. However, if the treatment for excessively increasing the circularity is performed, the wax exposed on the surface of the toner particles is stretched to the toner surface by physical contact at the time of treatment, and the chargeability and fluidity are lowered. On the other hand, when the average circularity is lower than the appropriate level, the toner has insufficient fluidity, and is considered to be inferior in durability. From this point of view, in the present invention, the total content A of the hydrocarbon wax and the average circularity B of the toner satisfy the relationship of 0.1 ≦ A ≦ 4 and 0.005A + 0.925 ≦ B ≦ −0.005A + 0.965. It is prescribed to satisfy. That is, in the lower limit relational expression of the average circularity, the lower the circularity, the finer powder is generated due to the wear of the toner when the toner is used, leading to the wax blade sticking, so that the amount of added wax is limited, and the more wax the more Since the wax content in the fine powder increases, the relationship of suppressing the generation of fine powder and increasing the circularity is shown. On the other hand, in the upper limit relational expression of the average circularity, the higher the circularity, the more spheroidizing treatment is required, and the wax tends to come out on the toner surface, leading to the adhesion of the wax to the blade. As the amount of wax increases, the wax content on the toner surface increases, indicating a relationship that lowers the circularity of the toner.

  The toner of the present invention contains at least polyester as a binder resin.

  The polyester is not particularly limited, and can be obtained by polycondensing a raw material monomer containing an alcohol component composed of a divalent or higher alcohol and a carboxylic acid component composed of a divalent or higher carboxylic acid compound.

  As the dihydric or higher alcohol, from the viewpoint of the storage stability of the toner, the formula (I):

(In the formula, RO is an alkylene oxide, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers indicating the average added mole number of alkylene oxide, and the sum of x and y is 1 to 16) (Preferably 1.5 to 5)
An alkylene oxide adduct of bisphenol A represented by The content of the alkylene oxide adduct of bisphenol A is preferably 50 mol% or more, more preferably 60 mol% or more, and further preferably 80 mol% or more in the alcohol component.

  Examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane and other ethylene oxide adducts having 2 carbon atoms, such as polyoxypropylene. Examples thereof include propylene oxide adducts having 3 carbon atoms such as -2,2-bis (4-hydroxyphenyl) propane.

  As alcohol components other than the alkylene oxide adduct of bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol A, sorbitol , Pentaerythritol, glycerol, trimethylolpropane and the like.

  Examples of the divalent or higher carboxylic acid compound include adipic acid, fumaric acid, maleic acid, succinic acid (e.g., n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isooctenyl succinic acid, Aliphatic carboxylic acids such as succinic acid substituted with alkyl groups having 1 to 20 carbon atoms or alkenyl groups having 2 to 20 carbon atoms such as isooctyl succinic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,2, 4-Benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, aromatic carboxylic acids such as pyromellitic acid, anhydrides of these acids and lower alkyl (C1-3) esters, etc. Is mentioned. Among these, terephthalic acid is preferable from the viewpoint of the storage stability of the toner, and 30 mol% or more of the carboxylic acid component is preferably terephthalic acid. In addition, the acids as described above, anhydrides of these acids, and alkyl esters of the acids are collectively referred to as carboxylic acid compounds in this specification.

  The polyester is preferably a crosslinked polyester obtained using a trivalent or higher monomer as the alcohol component and / or carboxylic acid component from the viewpoint of the softening point and grindability. The content of the trivalent or higher monomer is preferably 2 to 50 mol%, more preferably 10 to 30 mol%, based on the total amount of the alcohol component and the carboxylic acid component. As the trivalent or higher monomer, 1,2,4-benzenetricarboxylic acid (trimellitic acid) and its anhydride are preferable.

  The alcohol component may contain a monovalent alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound as appropriate from the viewpoints of molecular weight adjustment and offset resistance improvement.

  The polycondensation of the alcohol component and the carboxylic acid component can be performed, for example, in an inert gas atmosphere at a temperature of 180 to 250 ° C. From the viewpoint that the effects of the present invention are more remarkably exhibited, the ester It is preferable to carry out in the presence of the catalyst. Examples of esterification catalysts include dibutyltin oxide, titanium compounds, tin (II) compounds having no Sn—C bond, and the like. These may be used alone or in combination. Of these, dibutyltin oxide and a tin (II) compound having no Sn—C bond are preferred from the viewpoint of more remarkable effects of the present invention.

  Examples of the tin (II) compound having no Sn—C bond include a tin (II) compound having a Sn—O bond, a tin (II) compound having a Sn—X (X represents a halogen atom) bond, and the like. Preferably, a tin (II) compound having a Sn—O bond is more preferable.

Examples of tin (II) compounds having a Sn-O bond include tin (II) oxalate, tin (II) diacetate, tin (II) dioctanoate, tin (II) dilaurate, tin (II) distearate, diolein Carboxylic acid tin (II) having a carboxylic acid group having 2 to 28 carbon atoms such as tin (II) acid; dioctyloxy tin (II), dilauroxy tin (II), distearoxy tin (II), dioleoxy tin (II), etc. Dialkoxytin (II) having an alkoxy group having 2 to 28 carbon atoms; tin oxide (II); tin (II) sulfate and the like having a Sn—X (X represents a halogen atom) bond include chloride. Examples thereof include tin (II) halides such as tin (II) and tin (II) bromide. Among these, (R ¹ COO) ₂ Sn (where R ¹ is a fatty acid tin represented by an alkyl or alkenyl group 5 to 19 carbon ^{atoms) (II), (R 2} O) 2 Sn ( wherein R ² is an alkyl group having 6 to 20 carbon atoms Dialkoxy tin (II) and tin oxide represented by SnO (II) is preferably represented by the alkenyl a group), (R ¹ COO) fatty tin represented by ₂ Sn (II) and tin oxide (II ) Are more preferred, and tin (II) dioctanoate, tin (II) distearate, and tin (II) oxide are more preferred.

  In the present invention, the polyester may be a polyester modified to such an extent that the characteristics are not substantially impaired. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. Polyester.

  In the present invention, the polyester is preferably made of at least two kinds of resins from the viewpoints of storage stability and offset resistance. Specifically, from the viewpoint of improving the fixability of the toner, a high softening point polyester having a softening point of preferably more than 140 ° C. and 170 ° C. or less, more preferably 150 to 170 ° C., and a softening point of preferably 90 to A combination of low softening point polyesters at 140 ° C, more preferably 110-140 ° C is desirable. Further, the difference in softening point between the high softening point polyester and the low softening point polyester is preferably 20 to 60 ° C, more preferably 20 to 40 ° C, from the viewpoints of fixability and storage stability. In addition, when it consists of 3 or more types of resin, it is preferable that 2 types satisfy | fill the above from the one with much content, for example, when the 2nd and 3rd in the order with many are the same content, it is the largest one Preferably, the second one satisfies the above.

  The weight ratio of the high softening point polyester to the low softening point polyester (high softening point polyester / low softening point polyester) is preferably 1/9 to 9/1, and more preferably 2/8 to 8/2.

  When the binder resin is composed of two or more polyesters, the average softening point is preferably 120 to 160 ° C, and more preferably 135 to 155 ° C. In this specification, an average softening point means a weighted average softening point, and each softening point is measured by the method as described in the below-mentioned Example.

  The glass transition point of the polyester is preferably 50 to 85 ° C, more preferably 55 to 80 ° C. The acid value is preferably from 0.5 to 40 mgKOH / g, more preferably from 0.5 to 30 mgKOH / g, from the viewpoint of improving the positive chargeability. In this specification, a glass transition point and an acid value are measured by the method as described in the below-mentioned Example.

  The toner of the present invention may contain a binder resin other than the polyester as long as the effects of the present invention are not impaired. The polyester may be contained as a polyester-based resin such as polyester-polyamide, a composite resin having two or more resin components. Here, the composite resin refers to a resin in which a condensation polymerization resin such as polyester, polyester / polyamide and the like and an addition polymerization resin such as vinyl polymerization resin are partially chemically bonded. Even if it is obtained as a raw material, or obtained from a raw material monomer of one type of resin and another type of resin, it is obtained from a mixture of raw material monomers of two or more types of resin. However, in order to obtain a composite resin efficiently, those obtained from a mixture of raw material monomers of two or more resins are preferable. Examples of the binder resin other than the polyester resin include known resins used for toner, such as styrene-acrylic resin, epoxy resin, polycarbonate, and polyurethane. The content of the polyester is not particularly limited, but is preferably 60 to 100% by weight, more preferably 80 to 100% by weight, and still more preferably 100% by weight in the binder resin from the viewpoint of low-temperature fixability.

  The toner of the present invention contains at least a hydrocarbon wax as a release agent from the viewpoint of compatibility.

  Examples of the hydrocarbon wax include polyolefin wax, paraffin wax, petroleum wax, hydrocarbon wax obtained by the Fischer-Tropsch method, and derivatives and modified products thereof.

  Examples of the polyolefin wax include polyethylene wax and polypropylene wax. The melting point of the polyethylene wax is preferably 90 to 130 ° C, more preferably 95 to 125 ° C, and still more preferably 100 to 120 ° C, from the viewpoint of improving the fixability. In addition, the melting point of the polypropylene wax is preferably 110 to 160 ° C, more preferably 120 to 160 ° C, and further preferably 130 to 160 ° C, from the viewpoint of releasability at high temperatures. In the present specification, the melting point of the wax is measured by the method described in Examples below.

  As the paraffin wax, either one using coal as a raw material or one using petroleum as a raw material can be used, but paraffin wax obtained by refining petroleum is preferable from the viewpoint of improving durability. In addition, high-purity refined paraffin wax in which the petroleum wax extracted from petroleum is further separated and purified by distillation under reduced pressure to increase the proportion of linear hydrocarbons can be used. From the viewpoint of improving durability, the melting point of the paraffin wax is preferably 70 to 90 ° C, more preferably 70 to 85 ° C, and further preferably 75 to 85 ° C.

  Among the hydrocarbon waxes, polyolefin waxes are preferable from the viewpoint of durability.

  In the present invention, the hydrocarbon wax is preferably composed of two types of waxes having different melting points, and from the viewpoint of compatibility with the charge control agent, one of the two types is preferably a polyolefin wax. When two kinds of hydrocarbon waxes are used, the content of the polyolefin wax in the hydrocarbon wax is preferably 20 to 100% by weight, more preferably 30 to 100% by weight, and further 40 to 100% by weight. Preferably, 50 to 100% by weight is more preferable.

  Moreover, the melting point difference between the two hydrocarbon waxes is preferably 20 to 80 ° C, more preferably 30 to 70 ° C, and further preferably 30 to 60 ° C.

  The total content A of hydrocarbon wax in the toner is 0.1 to 4% by weight, preferably 0.2 to 4% by weight, more preferably 0.3 to 3.5% by weight, and still more preferably 0.4 to 3% by weight.

  The toner of the present invention may contain a release agent other than the hydrocarbon wax as long as the effects of the present invention are not impaired. Examples of the other mold release agent include ester wax, and the content of the other mold release agent is preferably 30% by weight or less, more preferably 15% by weight or less, and still more preferably 5% in the total amount of the mold release agent. % By weight or less.

  The toner of the present invention contains at least a styrene acrylic charge control resin as a charge control agent from the viewpoint of preventing toner adhesion to the charging blade.

  Further, from the viewpoint of improving the positive chargeability, a quaternary ammonium base-containing styrene acrylic copolymer obtained by copolymerizing a styrene acrylic resin with a quaternary ammonium salt is preferable.

  As the quaternary ammonium base-containing styrene acrylic copolymer, the formula (II):

(Wherein R ¹ represents a hydrogen atom or a methyl group)
A monomer represented by the formula (III):

(Wherein R ² represents a hydrogen atom or a methyl group, and R ³ represents an alkyl group having 1 to 6 carbon atoms)
And a monomer represented by the formula (IV):

(Wherein R ⁴ represents a hydrogen atom or a methyl group, R ⁵ and R ⁶ each independently represents an alkyl group having 1 to 4 carbon atoms)
Or a quaternized product thereof, preferably a compound obtained by a step including a polymerization step of a monomer mixture containing a monomer represented by the formula (IV).

The monomer represented by the formula (II) is preferably styrene in which R ¹ is a hydrogen atom, and the monomer represented by the formula (III) is preferably R ² is a hydrogen atom and R ³ is As the monomer having an alkyl group having 1 to 4 carbon atoms, more preferably butyl acrylate in which R ² is a hydrogen atom and R ³ is a butyl group, the monomer represented by the formula (IV) is preferably A monomer in which R ⁴ is a methyl group and R ⁵ and R ⁶ are a methyl group or an ethyl group, more preferably dimethylaminoethyl methacrylate in which R ⁴ , R ⁵ and R ⁶ are methyl groups, respectively, is desirable.

  The content of the monomer represented by the formula (II) in the monomer mixture is preferably 60 to 97% by weight, more preferably 70 to 90% by weight. The content of the monomer is preferably 1 to 33% by weight, more preferably 5 to 20% by weight, and the content of the monomer represented by the formula (IV) or a quaternized product thereof is preferably 2%. It is desirable to be -35 wt%, more preferably 5-20 wt%.

  Polymerization of the monomer mixture can be performed, for example, by heating the monomer mixture to 50 to 100 ° C. in an inert gas atmosphere in the presence of a polymerization initiator such as azobisdimethylvaleronitrile. The polymerization method may be any of solution polymerization, suspension polymerization or bulk polymerization, but is preferably solution polymerization.

  The content of the styrene acrylic charge control resin is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, and even more preferably 1.5 to 10% by weight in the toner.

  Furthermore, the toner of the present invention may contain a charge control agent other than the styrene-acrylic charge control resin as long as the effects of the present invention are not impaired. Examples of other charge control agents include known charge control agents, but the content of the styrene acrylic charge control resin in the charge control agent is preferably 70% by weight or more, more preferably 80% by weight or more, 90% by weight is more preferred, and substantially 100% by weight is more preferred.

  Examples of the colorant used in the toner of the present invention include carbon black; inorganic pigments such as iron black; I. Acetoacetic acid arylamide monoazo yellow pigments such as CI Pigment Yellow 1, 3, 74, 97, 98; I. C.I. Pigment Yellow 12, 13, 13, 17, etc. acetoacetic acid arylamide disazo yellow pigments; I. Solvent Yellow 19, 77, 79, C.I. I. Yellow dyes such as disperse yellow 164; I. Pigment Red 48, 49: 1, 53: 1, 57, 57: 1, 81, 122, 5 and the like; C.I. I. Red dyes such as Solvent Red 49, 52, 58, 8; I. Blue dyes and pigments of copper phthalocyanine and its derivatives such as CI Pigment Blue 15: 3; I. Green pigments such as CI Pigment Green 7 and 36 (phthalocyanine green) can be used. These dyes and pigments may be used alone or in combination of two or more. Usually, about 1 to 15 parts by weight is used for 100 parts by weight of the binder resin.

  In the present invention, in addition to a binder resin, a release agent, a charge control agent and a colorant, a conductive filler, a reinforcing pigment such as an extender pigment, a fibrous substance, an antioxidant, an anti-aging agent, a magnetic substance, etc. These additives may be blended as a toner raw material.

Since the toner of the present invention can easily adjust the circularity, it can be obtained by a method including a pulverization step. Moreover, it is preferable that the said method includes a melt-kneading process from a viewpoint of productivity. Specifically, toner materials such as a binder resin, a release agent, a charge control agent, and a colorant are uniformly mixed with a mixer such as a Henschel mixer or a ball mill, and then a hermetic kneader, a single or biaxial extrusion. , Melt and knead with an open roll type kneader, etc., cool, coarsely pulverize with a hammer mill, and further finely pulverize with a mechanical pulverizer such as an airflow pulverizer using a jet stream or an impact pulverizer They are obtained by classification to a predetermined particle size by a classifier using a swirling airflow or a classifier using the Coanda effect. The volume median particle diameter (D ₅₀ ) of the toner is preferably 3 to 15 μm, more preferably _{5 to} 10 μm. The content of particles having a particle size of 5 μm or less is preferably 8% by volume or less. In the present specification, the volume median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size.

  The toner of the present invention has the following formula:

The average circularity B of the toner is calculated by the following formula, the average circularity B of the toner is “peripheral length of a circle having the same area as the projected image of particles” and “peripheral length of the projected particle image” is a flow type particle image analysis. It is a value obtained by measuring in an aqueous dispersion system using an apparatus (FPIA-1000, FPIA-2000 or FPIA-3000; manufactured by Sysmex Corporation). Moreover, since the value obtained by the above-described analyzer is a value obtained as an average value of several thousand and at least 3000, the reliability of the average circularity in the present invention is extremely high. In the present specification, the average circularity measuring device is not limited to the above-mentioned device, and any device can be used as long as the average circularity can be obtained based on the above equation based on the same principle. May be measured.

The average circularity B of the toner of the present invention satisfies the following relationship with the content A of the hydrocarbon wax in the toner. That is,
When 0.1 ≦ A ≦ 4, 0.005A + 0.925 ≦ B ≦ −0.005A + 0.965 is satisfied,
Preferably, 0.2 ≦ A ≦ 3.5 and 0.005A + 0.925 ≦ B ≦ −0.005A + 0.965,
More preferably, 0.2 ≦ A ≦ 3.0 and 0.005A + 0.925 ≦ B ≦ −0.005A + 0.965,
More preferably, 0.2 ≦ A ≦ 2.5 and 0.005A + 0.925 ≦ B ≦ −0.005A + 0.965,
Even more preferably, 0.3 ≦ A ≦ 2.5 and 0.005A + 0.925 ≦ B ≦ −0.005A + 0.965,
Even more preferably, 0.3 ≦ A ≦ 2.5 and 0.005A + 0.930 ≦ B ≦ −0.005A + 0.965,
Even more preferably, it is desirable to satisfy the relationship of 0.3 ≦ A ≦ 2.5 and 0.005A + 0.930 ≦ B ≦ −0.005A + 0.960. The circularity can be adjusted by selecting the toner pulverization conditions. Specifically, it can be adjusted through a process using an impact pulverizer after a process of producing finely pulverized toner particles having a relatively low average circularity with an airflow pulverizer. In order to increase the circularity, the peripheral speed of the impact pulverizer may be increased, or the treatment with the impact pulverizer may be performed a plurality of times.

  The toner of the present invention may be further externally treated with an external additive such as inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide and zinc oxide, and organic fine particles such as resin fine particles.

  The toner of the present invention can be suitably used for an oilless fixing type apparatus regardless of the development method (contact development, non-contact development, cleaner-less). The toner of the present invention is particularly effective because the effects of the present invention are remarkably exhibited when used for non-magnetic one-component development that places a heavy load on the toner. Furthermore, the toner of the present invention containing a polyester resin is particularly suitable as a color toner because of its excellent transparency.

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

[Glass transition point of resin]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the temperature was raised to 200 ° C, and the sample cooled to 0 ° C at a cooling rate of 10 ° C / min was measured at a heating rate of 10 ° C / min. The temperature at the intersection of the extended line of the baseline below the maximum peak temperature of endotherm and the tangent showing the maximum slope from the peak rising portion to the peak apex.

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

[Volume-median particle size of toner (D ₅₀ )]
Measuring instrument: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 50μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
Electrolyte: Isoton II (Beckman Coulter)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) is dissolved in the electrolytic solution to a concentration of 5% by weight to obtain a dispersion.
Dispersion conditions: 10 mg of a measurement sample is added to 5 mL of the above dispersion, and dispersed for 1 minute with an ultrasonic disperser, then 25 mL of electrolyte is added, and further dispersed for 1 minute with an ultrasonic disperser. Prepare a dispersion.
Measurement conditions: By adding the sample dispersion to 100 mL of the electrolytic solution, the particle size of 30,000 particles is adjusted to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured, Determine the volume median particle size (D ₅₀ ).

[Average circularity of toner]
The average circularity is measured under the following conditions using a flow particle image analyzer “FPIA-3000” (manufactured by Sysmex Corporation).
Electrolyte: Isoton II (Beckman Coulter)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) is dissolved in the electrolytic solution to a concentration of 5% by weight to obtain a dispersion.
Dispersion conditions: Add 10 mg of measurement sample to 10 mL of the dispersion, disperse for 1 minute with an ultrasonic disperser, add 10 mL of distilled water, and then disperse for another 1 minute with an ultrasonic disperser. Prepare the solution.
Measurement conditions: The number of effective analyzes is set to 3000, and the toner shape and distribution are measured.

[Melting point of release agent]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the temperature was raised to 200 ° C, and the sample was cooled to 0 ° C at a temperature drop rate of 10 ° C / min. The maximum peak temperature of heat of fusion is taken as the melting point.

Resin production example 1 (Synthesis example of polyester resin)
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane (3500 g), isododecenyl succinic anhydride (50 g), fumaric acid (1110 g), hydroquinone (2.5 g) and dibutyltin oxide (5 g) were placed in a four-necked flask and a thermometer. A stainless stir bar, a flow-down condenser, and a nitrogen introduction tube were attached, and the mixture was stirred in a mantle heater at a temperature of 210 ° C.
The degree of polymerization was monitored from the softening point according to ASTM E28-67, and the reaction was terminated when the softening point reached 159 ° C.
The glass transition temperature (Tg) of the obtained resin was 64 ° C. with one peak. The acid value of the resin was 5.5 mg KOH / g.
This is designated as resin A.

Resin production example 2 (polyester resin synthesis example)
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane (3500 g), isododecenyl succinic anhydride (50 g), fumaric acid (1110 g), hydroquinone (2.5 g) and dibutyltin oxide (5 g) were placed in a four-necked flask and a thermometer. A stainless stir bar, a flow-down condenser, and a nitrogen introduction tube were attached, and the mixture was stirred in a mantle heater at a temperature of 210 ° C.
The degree of polymerization was tracked from the softening point according to ASTM E28-67, and the reaction was terminated when the softening point reached 135 ° C.
The glass transition temperature (Tg) of the obtained resin was 60 ° C. with one peak. The acid value of the resin was 6 mg KOH / g.
This is designated as resin B.

Toner Production Example 1 (Examples 1 to 14, Comparative Examples 1 to 10 and 13)
Binder resin 60 parts by weight, resin B 40 parts by weight, colorant carbon black "Mougul-L" (manufactured by Cabot) 5.0 parts by weight, charge control agent styrene acrylic charge control resin "FCA-201-PS" (Fujikura Kasei Co., Ltd.) 5.0 parts by weight and the release agent shown in Table 1 were mixed with a Henschel mixer, then melt-kneaded with a twin screw extruder, using an airflow pulverizer, a collision plate pulverizer, and a dispersion separator. Crushing and classification were performed to obtain toner base particles having a volume median particle size (D ₅₀ ) of 8.0 μm. The average softening point of the binder resin was 149.4 ° C.

Toner Production Example 2 (Comparative Example 11)
As in Example 1, except that 100 parts by weight of styrene acrylic resin (non-crosslinked, weight average molecular weight 290,000, number average molecular weight 3200) was used instead of resin A 60 parts by weight and resin B 40 parts by weight as the binder resin. Manufactured.

Toner Production Example 3 (Comparative Example 12)
It was produced in the same manner as in Example 1 except that quaternary ammonium salt of molybdic acid “TP-415” (Hodogaya Chemical Co., Ltd.) was used in place of “FCA-201-PS” as the charge control agent.

  In the pulverization of the toner production example 1, the primary treatment by the airflow pulverizer “Jet Mill IDS” (manufactured by Nippon Pneumatic Co., Ltd.) and the secondary treatment by the impact pulverizer “Kryptron” (manufactured by Kawasaki Heavy Industries, Ltd.). Spherical treatment including tertiary treatment was performed. Table 1 shows the average circularity of the toner after processing by each pulverizer.

  To 100 parts by weight of the toner base particles obtained, 0.5 part by weight of “NAX-50” (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., average particle size of about 30 nm), “RX-300” (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd.) The positively charged toners of Examples 1 to 14 and Comparative Examples 1 to 13 subjected to the external additive treatment were obtained by adding 0.5 parts by weight of an average particle size of about 8 nm and mixing with a Henschel mixer.

Test Example 1 [Durability]
Mount the toner obtained in the non-magnetic one-component developing device "HL-5070DN" (Brother Kogyo Co., Ltd.) for positively chargeable toner, and print a chart with a printing rate of 5%. A solid image was printed and the presence or absence of image streaks due to blade fixation was confirmed. The table shows the maximum number of images where no image streak occurs. The results are shown in Table 1.

  From the above results, it can be seen that the toner of the example is superior in durability to the toner of the comparative example. Among them, the toners of Examples 4 to 6 have the same composition and content of the release agent, but differ in the number of printing sheets only by the difference in the average circularity of the toner. It is suggested that there is a certain relationship between the average circularity of. Further, it can be seen from the comparison between the toners of Examples 2 and 3 and the toners of Examples 13 and 14 that a polyolefin wax is suitable as the hydrocarbon wax. On the other hand, in Comparative Example 11 in which the styrene acrylic resin in which the polyolefin wax is relatively easily dispersed was used as the binder resin, the dispersibility of the wax became too good. Excessive exposure to low durability. Since Comparative Example 12 in which the charge control agent is not a styrene acrylic resin is difficult to disperse the hydrocarbon wax in the polyester, Comparative Example 13 in which the ester wax is used as the release agent is a charge control of polyester and styrene acrylic. Since the compatibility of resin is low, it is thought that all are inferior in durability.

  The positively chargeable toner of the present invention is suitably used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like.

Claims (5)

A positively chargeable toner comprising a binder resin, a release agent, a charge control agent, and a colorant, wherein the binder resin is polyester, the release agent is a hydrocarbon wax, and the charge control agent is styrene. It is obtained by a method containing at least an acrylic charge control resin and including a pulverization step. The total content A (% by weight) of hydrocarbon wax in the toner and the average circularity B of the toner are expressed by the following formula (I ) And (II).
0.1 ≦ A ≦ 4 (I)
0.005A + 0.925 ≦ B ≦ -0.005A + 0.965 (II)   The positively chargeable toner according to claim 1, wherein the charge control resin is a quaternary ammonium base-containing styrene acrylic copolymer.   The positively chargeable toner according to claim 1, wherein the hydrocarbon wax contains at least a polyolefin wax.   The positively chargeable toner according to claim 1, wherein the hydrocarbon wax comprises at least two kinds of waxes having melting points of 20 to 80 ° C. The binder resin is a combination of a high softening point polyester having a softening point of more than 140 ° C and not more than 170 ° C and a low softening point polyester having a softening point of 90 to 140 ° C, and the average softening point of the binder resin The positively chargeable toner according to claim 1, wherein the toner has a temperature of 120 to 160 ° C.