JP5288766B2 - Toner for electrophotography - Google Patents

Description

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

In the electrophotographic field, a toner that satisfies the demand for higher speed and higher image quality is desired. On the other hand, a toner is disclosed in which a part of the polyol component is a propylene oxide adduct of bisphenol A having a primary hydroxyl group (see Patent Document 1). Furthermore, a toner using a polyester resin and a specific paraffin wax is disclosed (see Patent Document 2).
JP 2006-17954 A JP 2006-99098 A

  A toner having a high content of a propylene oxide adduct of bisphenol A having a primary hydroxyl group is excellent in fixability but inferior in durability. Further, when a binder resin having a high softening point and a low melting point paraffin wax are used, the durability is excellent, but the low-temperature fixability is not sufficient.

  An object of the present invention is to provide an electrophotographic toner that has both low-temperature fixability and durability, and is excellent in durability under high temperature and high humidity.

  The present invention relates to an electrophotographic toner containing a wax having a melting point of 60 to 95 ° C., a colorant, and a polyester as a binder resin, wherein the polyester has the formula (I):

Wherein R ¹ and R ² are each independently —CH (CH ₃ ) CH ₂ — and / or —CH ₂ CH (CH ₃ ) —, and m R ¹ and n R ² May be the same or different, and m and n are positive numbers)
A polyester obtained by polycondensation of an alcohol component containing a propylene oxide adduct of bisphenol A and a carboxylic acid component, wherein the average addition mole number of the propylene oxide adduct of bisphenol A is 2.4 to 4.0. In the propylene oxide adduct of bisphenol A, the propylene oxide 2 mol adduct content is 60 mol% or less and the propylene oxide 4 mol adduct content is 10 mol% or more. The present invention relates to an electrophotographic toner having a primary hydroxyl group content of 10 mol% or less in all hydroxyl groups in an oxide adduct.

  The toner for electrophotography of the present invention exhibits an excellent effect that both low-temperature fixability and durability are achieved, and further, durability under high temperature and high humidity is also excellent.

  The low-temperature fixability of the toner is affected by the size of the softening point of the binder resin. However, as a result of extensive studies by the present inventors, it has been found that the fixing performance of the resin varies greatly depending on the monomer composition even at the same softening point. That is, it has been found that by using an alcohol component containing a specific amount of a specific propylene oxide adduct of bisphenol A, the low-temperature fixability is improved even at a similar softening point.

  Details of these phenomena are unknown, but flexible monomers (propylene oxide adduct of bisphenol A with 2 mol of propylene oxide added and propylene oxide adduct of bisphenol A with 4 mol added) are added to the main skeleton of the resin. It is presumed that by incorporating the polymer, the movement of the main chain of the polymer in the temperature range above the glass transition point becomes intense and the fixability at low temperature is improved. From this point of view, a larger effect can be obtained by increasing the total number of added moles than adding a small amount of the high mole adduct and combining only the average number of moles added. Further, it is presumed that by using such a polymer in combination with a low melting point wax, the compatibility between the polymer and the wax is good, so that the wax dispersibility is improved and the durability is ensured. Further, even under high temperature and high humidity, it is presumed that the durability is improved because the embedding of silica into the toner, which is considered to be caused by the localization of wax, is suppressed and the fluidity of the toner can be secured.

  The toner of the present invention comprises a polyester obtained by polycondensation of a specific wax, a colorant, which will be described later, and an alcohol component and a carboxylic acid component containing a specific amount of a specific propylene oxide adduct of bisphenol A as described above. It is included as a binder resin.

  The propylene oxide adduct of bisphenol A contained in the alcohol component has the formula (I):

Wherein R ¹ and R ² are each independently —CH (CH ₃ ) CH ₂ — and / or —CH ₂ CH (CH ₃ ) —, and m R ¹ and n R ² May be the same or different, and m and n represent a positive number, and the sum of m and n is preferably 1 to 18, more preferably 1 to 16, and still more preferably 1 to 14)
It is represented by The sum of m and n means the number of molecules of propylene oxide added to one molecule of bisphenol A.

  In the propylene oxide adduct of bisphenol A represented by the formula (I), the content of the propylene oxide adduct of bisphenol A added with 2 mol of propylene oxide is 60 mol% in the alcohol component from the viewpoint of low temperature fixability. Or less, preferably 10 to 55 mol%, more preferably 20 to 50 mol%, still more preferably 25 to 50 mol%. In addition, in this specification, adduct content for every addition mole number of propylene oxide is computed by the method as described in the below-mentioned Example.

  Similarly, in the propylene oxide adduct of bisphenol A represented by the formula (I), the content of the propylene oxide adduct of bisphenol A in which 4 mol of propylene oxide is added is an alcohol component from the viewpoint of storage stability of the toner. Among them, it is 10 mol% or more, preferably 10 to 30 mol%, more preferably 10 to 25 mol%, still more preferably 15 to 25 mol%.

  Examples of the propylene oxide adduct of bisphenol A represented by the formula (I) other than the above include adducts with 1 mol of propylene oxide added, adducts with 3 mol added, adducts with 5 mol added, and the like. These compounds may be contained within a range not impairing the effects of the present invention, and the content of propylene oxide adduct of bisphenol A to which 5 mol of propylene oxide has been added is from the viewpoint of storage stability of the toner. In an alcohol component, 1-10 mol% is preferable and 2-8 mol% is more preferable.

  The total content of the propylene oxide adduct of bisphenol A represented by the formula (I) is preferably 30 mol% or more, more preferably 50 to 100 mol% in the alcohol component from the viewpoint of toner storage stability. More preferably, it is 70-100 mol%.

  The average addition mole number of the propylene oxide adduct of bisphenol A represented by the formula (I) is from 2.4 to 4.0, preferably from 2.7 to 3.7, more preferably from the viewpoint of low-temperature fixability and image quality such as stripes and fog. It is 2.7 to 3.4, more preferably 2.9 to 3.4. The average number of moles added here means the average number of moles of propylene oxide added to 1 mole of bisphenol A.

  The primary hydroxyl group content in the total hydroxyl groups in the propylene oxide adduct of bisphenol A represented by the formula (II) is 10 mol% or less from the viewpoint of image quality such as stripes and fog, preferably 2 It is -8 mol%, More preferably, it is 2-6 mol%. In the present specification, the content of primary hydroxyl groups is calculated by the method described in the examples described later.

  Examples of the method for preparing the propylene oxide adduct of bisphenol A represented by the formula (I) include a method of adding propylene oxide to bisphenol A in the presence of a catalyst, and if necessary, after the addition reaction It may be aged for a certain time. In addition, the distribution of the number of moles of propylene oxide in the resulting adduct is often influenced by the amount of catalyst and the addition reaction temperature, and may also be affected by the aging time. For example, when the amount of catalyst used is large, when the addition reaction temperature is high, or when the aging time is long, the distribution of the number of moles added of the propylene oxide adduct tends to be broad.

  Specifically, the average added mole number of propylene oxide is 2.4 to 4.0, for example, the content of propylene oxide 2 mol adduct in the propylene oxide adduct of bisphenol A is 60 mol% or less and 4 mol of propylene oxide. A propylene oxide adduct of bisphenol A having an adduct content of 10 mol% or more is obtained by reacting 2.4 to 4.0 mol of propylene oxide in the presence of a catalyst with respect to 1 mol of bisphenol A, and then aging. can get. Propylene oxide 4 mol adduct content is controlled by the amount of catalyst, addition reaction temperature, and aging after introduction of propylene oxide. It can be adjusted by removing the high molar adduct by washing. When the amount of propylene oxide 4 mol adduct is small, a disproportionation reaction is caused by a method such as increasing the amount of catalyst, increasing the temperature of the addition reaction, or extending the aging time after addition, and Can be increased. In view of production efficiency and subsequent residual alkali metal, it is preferable to increase and adjust the addition reaction temperature.

  Examples of the catalyst include basic catalysts such as potassium hydroxide and sodium hydroxide, and acid catalysts such as boron trifluoride and aluminum chloride. From the viewpoint of reducing the primary hydroxyl group content in the terminal hydroxyl group in the propylene oxide adduct of bisphenol A, a basic catalyst is preferably used, and potassium hydroxide is preferred as the basic catalyst. The primary hydroxyl group content can be adjusted by using an acid catalyst in combination with the basic catalyst. For example, the primary hydroxyl group content can be increased by carrying out the reaction with an acid catalyst after the addition reaction with a basic catalyst. The total amount of catalyst used is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of bisphenol A obtained.

  The temperature of the addition reaction is preferably 20 to 200 ° C, more preferably 100 to 140 ° C, from the viewpoint of reaction rate and quality. The pressure for the addition reaction is preferably 0.005 to 0.9 MPa, more preferably 0.01 to 0.6 MPa.

  The aging time after addition is preferably 0.1 to 10 hours, more preferably 0.5 to 5 hours.

  Divalent alcohols other than the propylene oxide adduct of bisphenol A represented by the formula (I) include ethylene oxide adducts of bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neo Examples include pentyl glycol, polyethylene glycol, polypropylene glycol, and hydrogenated bisphenol A.

  Examples of the trihydric or higher polyhydric alcohol include sorbitol, pentaerythritol, glycerin, trimethylolpropane and the like.

  On the other hand, in the carboxylic acid component, divalent carboxylic acid compounds include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid; oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutacone An aliphatic dicarboxylic acid such as succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms such as acid, succinic acid, adipic acid, dodecenyl succinic acid, octyl succinic acid; Examples thereof include anhydrides and alkyl (C1-3) esters of these acids. Of these, aromatic dicarboxylic acid compounds are preferred from the viewpoint of chargeability, terephthalic acid and isophthalic acid are more preferred, and terephthalic acid is even more preferred. 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 content of the aromatic dicarboxylic acid compound is preferably 55 to 99 mol%, more preferably 70 to 90 mol% in the carboxylic acid component.

  Examples of the trivalent or higher polyvalent carboxylic acid compound include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid and acid anhydrides thereof, lower alkyl (C1-C3) ester etc. are mentioned.

  The content of the trivalent or higher polyvalent carboxylic acid compound is preferably 3 to 49 mol%, more preferably 10 to 45 mol%, still more preferably 20 to 40 mol% in the carboxylic acid component from the viewpoint of grindability. .

  The content of trivalent or higher raw material monomers (trivalent or higher polyhydric alcohol and trivalent or higher polyvalent carboxylic acid compound) is preferably 1 to 25 mol%, more preferably 3 to 23 mol% in all raw material monomers. Preferably, 7 to 21 mol% is more preferable.

  Further, the alcohol component and the carboxylic acid component may appropriately contain a monovalent alcohol or a monovalent carboxylic acid compound from the viewpoint of adjusting the molecular weight.

  Polyester is, for example, an alcohol component and a carboxylic acid component in an inert gas atmosphere, if necessary, using an esterification catalyst (for example, a metal compound such as a tin catalyst or a titanium catalyst) at a temperature of 180 to 250 ° C. It can be produced by condensation polymerization.

  As the tin catalyst, in addition to a tin compound having a Sn—C bond such as dibutyltin oxide, a tin (II) compound having no Sn—C bond can be used. Examples of tin (II) compounds having no Sn—C bond include tin (II) oxalate, tin (II) acetate, tin (II) octoate, tin (II) octylate (2-ethylhexanoic acid). Tin (II)), tin laurate (II), tin stearate (II), tin oleate (II) and other carboxylic acid tin (II) having a carboxylic acid group having 2 to 28 carbon atoms; octyloxy tin ( II), Lauroxytin (II), Stearoxytin (II), Oleyloxytin (II), etc., alkoxytin (II) having an alkoxy group having 2 to 28 carbon atoms; tin (II) oxide; tin (II) sulfate; chloride Examples thereof include tin (II) halides such as tin (II) and tin bromide (II). Among these, tin (II) octylate is preferable.

  The amount of the esterification catalyst present in the reaction system is preferably 0.05 to 1 part by weight, more preferably 0.1 to 0.8 part by weight, based on 100 parts by weight of the total amount of the alcohol component and the carboxylic acid component.

  The softening point of the polyester is preferably 70 to 140 ° C., preferably 80 to 140 ° C., more preferably 85 to 135 ° C., from the viewpoint of fixability.

  The glass transition point of the polyester is preferably 45 to 70 ° C., more preferably 47 to 65 ° C., and further preferably 50 to 65 ° C. from the viewpoints of fixability and storage stability.

  Furthermore, the toner of the present invention may contain a composite resin having the polyester and vinyl resin as a binder resin.

  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. Examples of the binder resin other than the polyester include known resins used for toner, for example, styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, and the like, and the softening point is preferable from the viewpoint of securing a non-offset region. 90-170 ° C., more preferably 95-155 ° C., more preferably 100-145 ° C., glass transition point is preferably 45-75 ° C., more preferably 50-70 ° C., more preferably 53-65 ° C. desirable. 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 wax in the present invention has a melting point of 60 to 95 ° C., preferably 60 to 90 ° C., more preferably 70 to 90 ° C., from the viewpoint of low-temperature fixability of the toner and durability under high temperature and high humidity. Have

  The types of wax used in the present invention include low molecular weight polypropylene, low molecular weight polyethylene, low molecular weight polypropylene polyethylene copolymer, microcrystalline wax, paraffin wax, Fischer-Tropsch wax, and paraffin wax such as oxides thereof, carnauba wax. And ester waxes such as montan wax, sasol wax and their deoxidized wax, fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts and the like. Among these, paraffin wax and ester wax are preferable from the viewpoint of durability of the toner under high temperature and high humidity, and paraffin wax is more preferable from the viewpoint of low temperature fixability. The wax may be contained alone or in admixture of two or more. The wax content is preferably 0.1 to 20 parts by weight and more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  In the present invention, as the colorant, all of dyes and pigments used as toner colorants can be used, such as carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, CI. Pigment Blue 15: 3, Rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Disazo Yellow, etc. can be used. The toner of the present invention can be either black toner or color toner. There may be. The content of the colorant is preferably 1 to 40 parts by weight and more preferably 2 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  The toner of the present invention further includes a charge control agent, a magnetic powder, a fluidity improver, a conductivity modifier, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, an antiaging agent, and a cleaning property improving agent. Such additives may be appropriately contained.

  Charge control agents include triphenylmethane dyes containing tertiary amines as side chains, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives and other positively chargeable charge control agents, metal-containing azo complexes, and salicylic acid derivative metals. And negatively chargeable charge control agents such as compounds and metal compounds of benzylic acid derivatives. The content of the charge control agent is preferably 0.1 to 5 parts by weight, more preferably 0.3 to 3 parts by weight, and still more preferably 0.5 to 2 parts by weight with respect to 100 parts by weight of the binder resin.

The toner of the present invention may be a toner obtained by any conventionally known method such as a melt-kneading method, an emulsion phase inversion method, or a polymerization method, but from the viewpoint of productivity and dispersibility of the colorant, Pulverized toner by a kneading method is preferred. In the case of pulverized toner by melt kneading method, raw materials such as binder resin, colorant and wax are uniformly mixed with a mixer such as a Henschel mixer, and then a sealed kneader, a single or twin screw extruder, an open roll type It can be produced by melt-kneading with a kneader or the like, cooling, pulverizing and classifying. The volume median particle size (D ₅₀ ) of the toner is preferably 2 to 15 μm, more preferably 3 to 10 μm. 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 can be used as a one-component developing toner or as a two-component developer mixed with a carrier.

[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. . The amount of plunger drop of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[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)).

[Melting point of wax]
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 maximum peak temperature of heat of fusion is the melting point.

[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 electrolyte so as to have 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 ).

[Primary hydroxyl group content in propylene oxide adduct]
The primary hydroxyl group content is measured by ¹ H-NMR method.
(1) Sample preparation method (pretreatment)
About 30 mg of a measurement sample is weighed into an NMR sample tube having a diameter of 5 mm, and about 0.5 mL of deuterated solvent is added and dissolved. Thereafter, about 0.1 mL of trifluoroacetic anhydride is added to prepare a sample for analysis. Examples of the deuterated solvent include deuterated chloroform, deuterated toluene, deuterated dimethyl sulfoxide, deuterated dimethylformamide, and the like, and a solvent capable of dissolving the sample is appropriately selected.
(2) NMR measurement ¹ H-NMR measurement is performed under normal conditions.
(3) Primary hydroxyl group content calculation method By the above-mentioned pretreatment method, the hydroxyl group at the end of the propylene oxide adduct of bisphenol A reacts with the added trifluoroacetic anhydride to become a trifluoroacetic acid ester. As a result, a signal derived from a methylene group to which a primary hydroxyl group is bonded is observed at around 4.3 ppm, and a signal derived from a methine group to which a secondary hydroxyl group is bonded is observed at around 5.2 ppm. The primary hydroxyl group content is calculated by the following formula.
Primary hydroxyl group content (%) = [a / (a + 2 × b)] × 100
In the formula, a is an integral value of a signal derived from a methylene group to which a primary hydroxyl group is bonded in the vicinity of 4.3 ppm, and b is an integrated value of a signal derived from a methine group to which a secondary hydroxyl group is bonded in the vicinity of 5.2 ppm.

[Adduct content per number of moles added in propylene oxide adduct]
The content of the adduct is measured by the following method using GC (gas chromatograph).
(1) Pretreatment (silylation of sample)
Take 40-60 mg of sample in 5 mL of a space vial, add 1 mL of silylating agent (TH, manufactured by Kanto Chemical Co., Inc.), dissolve in a hot water bath (50-80 ° C.), and then shake to silylate. . After standing, the separated supernatant is used as a measurement sample.
(2) Measuring equipment
GC: GC14B (manufactured by Shimadzu Corporation)
(3) Measurement conditions Analytical column: Packing material Silicon OV-17 (60 / 80mesh product) manufactured by GL Sciences, length 1 m × diameter 2.6 mm
Carrier: He
Flow rate condition: 1mL / min
Inlet temperature: 300 ° C
Oven temperature condition Start temperature: 100 ℃
Temperature increase rate: 8 ℃ / min
End temperature: 300 ℃
Holding time: 25min
(4) Quantification of adduct The weight ratio is obtained from the peak area corresponding to each component detected by gas chromatography, and the molar ratio is obtained by converting the weight ratio into the molecular weight.

Production Example 1 of propylene oxide adduct
In an autoclave equipped with stirring and temperature control, 228 g (1 mol) of bisphenol A and 2 g of potassium hydroxide are introduced, and 174 g (3 mol) of propylene oxide is introduced at 135 ° C. under a pressure in the range of 0.1 to 0.4 MPa. The addition reaction was performed for 3 hours. 16 g of an adsorbent “KYOWARD 600” (manufactured by Kyowa Chemical Industry Co., Ltd .: 2MgO · 6SiO ₂ · XH ₂ O) was added to the reaction product, and the mixture was aged by stirring at 90 ° C. for 30 minutes. Thereafter, filtration was performed to obtain a propylene oxide adduct A of bisphenol A.

Production example 2 of propylene oxide adduct
In an autoclave equipped with stirring and temperature control, 228 g (1 mol) of bisphenol A and 2 g of potassium hydroxide are introduced, and 139 g (2.2 mol) of propylene oxide is introduced at 135 ° C. under a pressure in the range of 0.1 to 0.4 MPa. The addition reaction was performed for 3 hours. 16 g of an adsorbent “KYOWARD 600” (manufactured by Kyowa Chemical Industry Co., Ltd .: 2MgO · 6SiO ₂ · XH ₂ O) was added to the reaction product, and the mixture was aged by stirring at 90 ° C. for 30 minutes. Thereafter, filtration was performed to obtain a propylene oxide adduct B of bisphenol A.

Production example 3 of propylene oxide adduct
In an autoclave equipped with stirring and temperature control, 3380 g (9.7 mol) of Compound B obtained in Production Example 2 above and 0.78 g (0.157 mmol) of tris (pentafluorophenyl) borane were added, and 619 g (10.7 g) of propylene oxide at 75 ° C. Mol) was introduced over 12 hours under a pressure in the range of 0.011 to 0.083 MPa, followed by addition reaction at 75 ° C. for 6 hours. Add 8.6 g of adsorbent “KYOWARD 1000” (Kyowa Chemical Industry Co., Ltd .: Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O) and 68 g of ion-exchanged water to the reaction product, and add ₂ at 65 ° C. After aging for a period of time, the temperature was raised to 70 ° C. and water was distilled off under a pressure of 0.4 kPa. Thereafter, filtration was performed to obtain a propylene oxide adduct C of bisphenol A.

Resin production example 1
The raw material monomer and tin (II) octylate shown in Table 1 were reacted at 230 ° C. in a nitrogen atmosphere in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple. After reacting until it reached 90%, the reaction was further continued until a desired softening point was obtained at 8.3 kPa to obtain Resins A, B and C. In the present specification, the reaction rate means a value defined by the value of the amount of produced reaction water (mol) / theoretical amount of produced water (mol) × 100.

Examples 1-4 and Comparative Examples 1-7
The binder resin, charge control agent, colorant and wax shown in Table 2 were mixed in advance using a Henschel mixer, melted and kneaded using a biaxial extruder, and pulverized using a collision plate pulverizer and a dispersion separator. Classification was performed to obtain an untreated toner.

  The amount of external additive shown in Table 2 was added to 100 parts by weight of the obtained untreated toner and mixed with a Henschel mixer to obtain toners of Examples 1 to 4 and Comparative Examples 1 to 7.

The external additives used in Table 2 are as follows.
Si-1: RY-50 (hydrophobic silica), manufactured by Nippon Aerosil Co., Ltd., average particle size of 40 nm,
Hydrophobic treatment agent dimethylsiloxane, BET specific surface area before hydrophobization treatment 50m ² / g
Si-2: H30TD (hydrophobic silica), manufactured by Wacker, average particle size 8 nm,
Hydrophobic treatment agent dimethylsiloxane, BET specific surface area before hydrophobization treatment 300m ² / g

Test Example 1 [low temperature fixability]
The toner shown in Table 2 was mounted on “Microline 5400” (manufactured by Oki Data Co., Ltd.), and an unfixed image having a solid image portion of 2 cm × 3 cm (toner adhesion amount: 1.1 mg / cm ² ) was obtained. Using an external fixing machine (fixing speed: 300 mm / sec) of “Microline 3050” (manufactured by Oki Data Co., Ltd.), the fixing temperature was sequentially increased from 130 ° C. to 200 ° C. by 10 ° C. to fix the unfixed image.

  “Scotch (registered trademark) Mending Tape 810” (manufactured by Sumitomo 3M, width: 18 mm) was pasted on the fixed image, rubbed from above with a weight of 1.25 kg, and then the tape was peeled off. The image density before and after the tape is peeled off is measured using an image density meter “GRETAG SPM50” (Gretag), and the ratio between the two (after peeling / before sticking) first exceeds 80%. Was used as the minimum fixing temperature, and the low temperature fixing property was evaluated according to the following evaluation criteria. The results are shown in Table 2. The paper used for the fixing test is L paper manufactured by XEROX.

[Evaluation criteria for low-temperature fixability]
A: Minimum fixing temperature is less than 150 ° C B: Minimum fixing temperature is 150 ° C or more and less than 170 ° C C: Minimum fixing temperature is 170 ° C or more and less than 180 ° C D: Minimum fixing temperature is 180 ° C or more

Test Example 2 [Streak (Durability)]
The printing speed of a commercially available printer “Microline 5400” (Oki Data Co., Ltd.) was adjusted, and the toner shown in Table 2 was mounted. When continuously printing up to 15000 sheets of text images with a printing rate of 2% on A4 size (210mm x 297mm) paper at a printing speed of 30 sheets / minute, streaks on the surface of the developing roller occur every 1000 sheets printed. The situation was visually observed, and streaks (durability) were evaluated according to the following evaluation criteria. The results are shown in Table 2.

[Evaluation criteria for streaks (durability)]
A: No streaking on the developing roller until 15000 sheets printed B: Streaks occur on the developing roller after 10000 sheets printing and before 15000 sheets printing C: Streaks on the developing roller before printing 10000 sheets Occurs

Test Example 3 [Durability under high temperature and high humidity]
Under the environment of a temperature of 32 ° C. and a humidity of 80%, the printing speed of a commercially available printer “Microline 5400” (manufactured by Oki Data Corporation) was adjusted, and the toner shown in Table 2 was mounted. When continuously printing up to 15000 sheets of text images with a printing rate of 2% on A4 size (210mm x 297mm) paper at a printing speed of 30 sheets / minute, streaks on the surface of the developing roller occur every 1000 sheets printed. The situation was visually observed, and the durability under high temperature and high humidity was evaluated according to the following evaluation criteria. The results are shown in Table 2.

[Evaluation criteria for durability under high temperature and high humidity]
A: No streaking on the developing roller until 15000 sheets printed B: Streaks occur on the developing roller after 10000 sheets printing and before 15000 sheets printing C: Streaks on the developing roller before printing 10000 sheets Occurs

  From the above results, compared with Comparative Examples 1 to 7, the toners of Examples 1 to 4 have excellent low-temperature fixability and less streaking. It can be seen that it is excellent in durability under high humidity. On the other hand, the same binder resin as that used in Example 1 was used. However, the toners of Comparative Examples 1 to 3 using a wax having a melting point of 101 ° C. or 127 ° C. were slightly inferior in low-temperature fixability. However, the durability under high temperature and high humidity was poor. Further, although the wax having a melting point of 80 ° C. is used, the toners of Comparative Examples 4 to 5 using the resin B in which the average added mole number of propylene oxide of bisphenol A is 2.1 are inferior in low-temperature fixability and have a melting point. Although the wax at 80 ° C. is used, the toners of Comparative Examples 6 to 7 using the resin C in which the primary hydroxyl group content of bisphenol A is 30 mol% are excellent in low temperature fixability but inferior in durability. It was a thing. Therefore, when a resin containing bisphenol A having an average added mole number of propylene oxide and a primary hydroxyl group content within a predetermined range and a wax having a specific melting point are used, low-temperature fixability is obtained. It can be seen that both durability and durability are excellent, and durability at high temperatures and high humidity is also excellent.

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

Claims (4)

An electrophotographic toner comprising a wax having a melting point of 60 to 95 ° C., a colorant, and a polyester as a binder resin, wherein the polyester has the formula (I):

Wherein R ¹ and R ² are each independently —CH (CH ₃ ) CH ₂ — and / or —CH ₂ CH (CH ₃ ) —, and m R ¹ and n R ² May be the same or different, and m and n are positive numbers)
A polyester obtained by polycondensation of an alcohol component consisting only of a propylene oxide adduct of bisphenol A and a carboxylic acid component in the presence of tin (II) octylate , and the propylene oxide of bisphenol A The average addition mole number of the adduct is 2.7 to 4.0, and in the propylene oxide adduct of bisphenol A, the content of the propylene oxide 2 mol adduct is 60 mol% or less and the content of the propylene oxide 4 mol adduct is 10 An electrophotographic toner (a binder resin, a colorant, and a release agent are at least included in the propylene oxide adduct of bisphenol A and the primary hydroxyl group content in all the hydroxyl groups is 10 mol% or less. An electrophotographic toner having a structure comprising a core particle contained therein and a shell layer covering the core particle Excluded).   2. The toner for electrophotography according to claim 1, wherein the propylene oxide 5 mol adduct content in the propylene oxide adduct of bisphenol A is 1 to 10 mol%.   The electrophotographic toner according to claim 1 or 2, wherein the propylene oxide adduct of bisphenol A is prepared in the presence of a basic catalyst.   The toner for electrophotography according to claim 1, wherein the wax is paraffin wax or ester wax.