JP5059561B2 - 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, and the like, and a method for producing the same.

  Various toners containing a wax have been studied from the viewpoint of improving the offset resistance of the toner. Considering a reduction in the fixing temperature, simplification of the fixing machine, colorization, etc., a toner containing a high content of wax is considered. desired. However, if the wax content is large, the dispersion diameter of the wax becomes large, which adversely affects durability, storage stability and the like.

For this reason, as means for improving the dispersibility of wax, a method of refining wax crystals with a nucleating agent (see Patent Documents 1 to 4), a method of improving the dispersibility of wax with an open roll kneader (Patent Document) 5).
JP-A-4-107467 JP-A-5-119508 JP 2000-292965 A JP-A-4-149559 JP 2000-75548 A

  However, if the wax crystals are made too fine by the nucleating agent, the refined wax crystals are aggregated, the dispersion is deteriorated, and the durability may be lowered.

  On the other hand, by improving the dispersibility of the wax using an open roll type kneader, the durability and storage stability are greatly improved, but the finely dispersed wax cannot be crystallized and is the original purpose. The effect on the offset resistance is not sufficiently exhibited, and the pulverization property at the time of toner production is also affected.

  An object of the present invention is to provide an electrophotographic toner in which polyolefin wax is finely and uniformly dispersed and is excellent in grindability, offset resistance and durability, and a method for producing the same.

The present invention
[1] An electrophotographic toner obtained by a method including a step of melt-kneading at least a binder resin, a polyolefin wax, and a wax auxiliary with an open roll kneader, wherein the polyolefin wax and the wax auxiliary are , Formula (A):
Tc ₂ -Tc ₁ > 5.0 (A)
(In the formula, Tc ₁ is the exothermic peak temperature (° C.) of polyolefin wax by differential scanning calorimetry, and Tc ₂ is 99/1 (polyolefin wax / wax auxiliary) of polyolefin wax and wax auxiliary by differential scanning calorimetry. Exothermic peak temperature (℃) of the mixture mixed by weight ratio)
And (2) a method for producing an electrophotographic toner comprising a step of melt-kneading at least a binder resin, a polyolefin wax and a wax auxiliary with an open roll kneader, The polyolefin wax and the wax auxiliary are represented by the formula (A):
Tc ₂ -Tc ₁ > 5.0 (A)
(In the formula, Tc ₁ is the exothermic peak temperature (° C.) of polyolefin wax by differential scanning calorimetry, and Tc ₂ is 99/1 (polyolefin wax / wax auxiliary) of polyolefin wax and wax auxiliary by differential scanning calorimetry. Exothermic peak temperature (℃) of the mixture mixed by weight ratio)
The present invention relates to a method for producing an electrophotographic toner that satisfies the requirements.

  The toner for electrophotography of the present invention has an excellent effect that the polyolefin wax is finely and uniformly dispersed and has good crushability, offset resistance and durability.

The toner for electrophotography of the present invention is obtained by a method including a step of using at least a binder resin, a polyolefin wax and a wax auxiliary as toner raw materials, and melt-kneading them with an open roll kneader. Wax and wax auxiliary are of formula (A):
Tc ₂ -Tc ₁ > 5.0 (A)
(In the formula, Tc ₁ is the exothermic peak temperature (° C) of polyolefin wax by differential scanning calorimetry (DSC), and Tc ₂ is 99/1 (polyolefin wax / wax assistant) of polyolefin wax and wax auxiliary by DSC measurement. Exothermic peak temperature (℃) of the mixture mixed at the weight ratio of
It has the big feature in the point which satisfies.

As described above, by improving the dispersibility of the wax using an open roll type kneader, the durability and storage stability are greatly improved. However, the finely dispersed wax cannot be crystallized, and the original purpose is achieved. The effect on the offset resistance is not sufficiently exhibited. This is presumably because the uncrystallized wax is compatible with the resin and the bleed-out effect due to melting cannot be obtained. Whether the wax is crystallized can be confirmed by measuring the amount of heat absorbed due to melting of the wax in the differential scanning calorimetry of the toner. However, in the present invention, by combining the polyolefin wax satisfying the formula (A) and the wax auxiliary agent, most of the wax compatible with the resin during the melt-kneading causes phase separation. Since the wax is crystallized by phase separation, the degree of crystallinity is increased without impairing the dispersibility of the wax. In the formula (A), the difference between Tc ₂ and Tc ₁ indicates that the crystallization of the polyolefin wax is promoted by the addition of the wax aid, and the larger the difference, the greater the polyolefin. It means that the crystallization of the wax proceeds and the peak temperature of the exotherm rises. From this point of view, the difference between Tc ₂ and Tc ₁ in formula (A) (Tc ₂ −Tc ₁ ) is larger than 5.0, preferably 5.5 or larger, more preferably 6 or larger, and the crystal diameter From this viewpoint, it is preferably 10 or less, more preferably 8 or less.

  In the present invention, examples of the binder resin include polyester, vinyl resin, epoxy resin, polycarbonate, polyurethane, and the like. Among these, polyester is preferable from the viewpoint of fixability. The polyester content in the binder resin is preferably 80% by weight or more, and more preferably 90% by weight or more.

  Polyester is obtained by using a carboxylic acid component and an alcohol component as raw material monomers and subjecting them to condensation polymerization.

  Examples of the alcohol component include polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane, which are represented by the formula (I):

(In the formula, R ¹ O represents an oxyalkylene group, R ¹ represents an ethylene and / or propylene group, x and y represent the number of added moles of alkylene oxide, each of which is a positive number, The average value of the sum is preferably 1 to 16, more preferably 1 to 8, and further preferably 1.5 to 4)
Aromatic diols such as alkylene oxide adducts of bisphenol represented by: ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6 -Aliphatic diols such as hexanediol, 1,4-butenediol, 1,3-butanediol and neopentyl glycol, and trihydric or higher polyhydric alcohols such as glycerin. Among these, from the viewpoint of toner durability and chargeability, an alkylene oxide adduct of bisphenol A represented by the formula (I) is preferable. The content of the alkylene oxide adduct of bisphenol A represented by the formula (I) is preferably 60 mol% or more, more preferably 80 mol% or more in the alcohol component.

  Examples of carboxylic acid components include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, etc. Aliphatic dicarboxylic acids; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid; And anhydrides of these acids, alkyl (1 to 3 carbon atoms) esters; rosins; rosins modified with fumaric acid, maleic acid, acrylic acid, and the like. Such acids, anhydrides of these acids, and alkyl esters of these acids are collectively referred to herein as carboxylic acid compounds.

  The alcohol component may contain a monovalent alcohol and the carboxylic acid component may contain a monovalent carboxylic acid compound as appropriate from the viewpoint of adjusting the molecular weight of the polyester and improving the offset resistance of the toner.

  The condensation polymerization of the alcohol component and the carboxylic acid component is preferably performed in the presence of an esterification catalyst. Preferable examples of the esterification catalyst in the present invention include titanium compounds, dibutyltin oxide, tin (II) compounds having no Sn—C bond, and the like. These may be used alone or in combination, but in the present invention, a tin (II) compound having no Sn—C bond is preferable from the viewpoint of toner durability.

  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 Sn-O bonds include tin (II) oxalate, tin (II) acetate, tin (II) octoate, tin (II) 2-ethylhexanoate, and tin (II) laurate. , Tin (II) carboxylate having a carboxylic acid group having 2 to 28 carbon atoms such as tin (II) stearate, tin (II) oleate; octyloxy tin (II), lauroxy tin (II), stearoxy tin (II) ), Alkoxytin (II) having an alkoxy group having 2 to 28 carbon atoms such as oleyloxytin (II); tin (II) oxide; tin (II) sulfate, Sn—X (X represents a halogen atom) Examples of the tin (II) compound having a bond include tin (II) halides such as tin (II) chloride and tin (II) bromide, and among these, from the standpoint of charge rising effect and catalytic ability , (R ¹ COO) ₂ Sn (wherein R ¹ represents an alkyl group or alkenyl group having 5 to 19 carbon atoms), (R ² O) ₂ Sn (where R ² Is C 6-20 alk An alkoxytin (II) represented by SnO or a tin (II) oxide represented by SnO, and a fatty acid tin (II) and tin oxide represented by (R ¹ COO) ₂ Sn (II) is more preferred, and tin (II) octoate, tin (II) 2-ethylhexanoate, tin (II) stearate and tin (II) oxide are more preferred.

  The abundance of the tin (II) compound is preferably 0.01 to 1 part by weight and more preferably 0.1 to 0.5 part by weight with respect to 100 parts by weight of the total amount of the alcohol component and the carboxylic acid component.

  The polyester is obtained by polycondensing an alcohol component and a carboxylic acid component at 180 to 250 ° C., for example, in an inert gas atmosphere, if necessary, in the presence of an esterification catalyst.

  The softening point of the polyester is preferably 80 to 150 ° C, more preferably 85 to 145 ° C, and still more preferably 90 to 145 ° C.

  The glass transition point of the polyester is preferably 40 to 80 ° C., more preferably 50 to 70 ° C., from the viewpoint of toner pulverization and storage properties.

  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. And a composite resin having two or more kinds of resin units including a polyester unit.

  Examples of the polyolefin wax include polyethylene wax and polypropylene wax, and polyethylene wax is preferable from the viewpoint of offset resistance of the toner.

  The melting point of the polyolefin wax is preferably 60 to 120 ° C., more preferably 70 to 90 ° C., from the viewpoint of toner durability and fixing properties.

  The content of the polyolefin wax is preferably 3 to 20 parts by weight, more preferably 4 to 10 parts by weight, and further preferably 5 to 8 parts by weight with respect to 100 parts by weight of the binder resin, from the viewpoint of toner fixing properties. .

  A release agent other than the polyolefin wax may be contained as appropriate.

  In the present invention, the wax auxiliary agent is appropriately selected from those satisfying the above formula (A). From the viewpoint of dispersibility, a sorbitol compound and an organic phosphate compound are preferable. Specific examples of the sorbitol-based compound include, for example, formula (II):

(Wherein R ² and R ³ are the same or different and are hydrocarbon groups having 1 to 6 carbon atoms)
The sorbitol type compound represented by these is mentioned.

  Specific examples of the organic phosphoric acid compound include, for example, the formula (III):

(Wherein R ^{4 to} R ⁷ are the same or different and each represents an alkyl group which may have a substituent, and M represents a hydrogen atom, an alkali metal or an ammonium group)

Examples of the alkyl group optionally having a substituent represented by R ^{4 to} R ⁷ include a methyl group, an ethyl group, an isopropyl group, a butyl group, a tert-butyl group, an octyl group, a tert-octyl group, and a decyl group. Group, hexyl group, hexadecyl group, dodecyl group, 2-hydroxyethyl group, carboxymethyl group, cyanomethyl group, 2-methoxyethyl group, benzyl group, 2-phenylmethyl group, trifluoromethyl group, hydroxymethyl group, methoxymethyl Group, dicyanomethyl group, aminomethyl group, N-methylaminomethyl group, mercaptomethyl group, methylthiomethyl group, N, N-dimethylaminomethyl group, chloromethyl group, bromomethyl group and the like.

  The content of the wax auxiliary is preferably 3 to 100 parts by weight, more preferably 5 to 50 parts by weight, and still more preferably 10 to 30 parts by weight with respect to 100 parts by weight of the polyolefin wax.

  The toner of the present invention further includes a colorant, charge control agent, magnetic powder, fluidity improver, conductivity modifier, extender pigment, reinforcing filler such as fibrous substance, antioxidant, anti-aging agent, cleaning Additives such as property improvers may be contained as appropriate.

  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, rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Isoindoline, Disazo Yellow and the like can be used, and the toner of the present invention may be either black toner or color toner. 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 can be obtained by a method including a step of melt-kneading a toner raw material containing at least the binder resin, wax, and wax auxiliary agent with an open roll kneader.

  In melt kneading, it is preferable to uniformly mix toner raw materials such as a binder resin, and then use an open roll kneader from the viewpoint of wax dispersibility. The raw materials may be mixed at once, or may be divided and mixed.

  Examples of the mixer used for mixing the toner raw material include a Henschel mixer and a super mixer. From the viewpoint of dispersibility of internal additives such as a colorant and wax, a Henschel mixer is preferable.

  In the melt kneading of the toner raw material, it is preferable to use a continuous open roll type kneader equipped with a supply port and a kneaded product discharge port provided along the axial direction of the roll because wax can be efficiently and highly dispersed.

  The toner raw material mixture may be supplied to the kneader from one supply port, or may be divided and supplied to the kneader from a plurality of supply ports. Is preferably supplied to the kneader from one supply port.

  The open roll type kneader means an open type kneading unit, and can easily dissipate heat of kneading generated during melt kneading. The open roll type kneader is preferably a kneader equipped with at least two rolls, and the open roll type kneader suitably used in the present invention has two rolls with different peripheral speeds, that is, A kneading machine provided with two rolls, a high rotation side roll having a high peripheral speed and a low rotation side roll having a low peripheral speed. In the present invention, from the viewpoint of dispersibility, it is desirable that the high rotation side roll is a heating roll and the low rotation side roll is a cooling roll.

  The temperature of the roll can be adjusted by, for example, the temperature of the heat medium passed through the inside of the roll, and each roll may be divided into two or more and the heat medium having different temperatures may be passed through each roll.

  The temperature of the roll is preferably 100 to 160 ° C. at the raw material charging side end of the high rotation side roll, and preferably 20 to 100 ° C. at the raw material charging side end of the low rotation side roll. When the temperature of the raw material charging side end of the high rotation side roll is increased, the dispersion diameter of the wax tends to increase, and when the temperature is lowered, the dispersion diameter of the wax tends to decrease.

  The high rotation side roll with a high peripheral speed has a difference in set temperature between the raw material input side end and the kneaded product discharge side end of 20 to 70 ° C. from the viewpoint of preventing the kneaded product from being detached from the roll. Preferably, it is 30-60 degreeC. The low rotation side roll with a low peripheral speed is preferably 0 to 60 ° C. from the viewpoint of wax dispersibility, and the temperature difference between the raw material input side end and the kneaded product discharge side end is preferably 0 to 50 ° C. It is more preferable that It is preferable that the raw material input side end has a higher set temperature than the kneaded product discharge side end.

  The peripheral speed of the high rotation side roll is preferably 2 to 100 m / min, more preferably 5 to 75 m / min. The peripheral speed of the low rotation side roll is preferably 2 to 100 m / min, more preferably 4 to 60 m / min, and further preferably 4 to 50 m / min. Further, the ratio of the peripheral speeds of the two rolls (low rotation side roll / high rotation side roll) is preferably 1/10 to 9/10, more preferably 3/10 to 8/10. Increasing the ratio of the peripheral speeds increases the dispersion diameter of the wax, and decreasing the ratio tends to decrease the average dispersion diameter of the wax.

  The gap (clearance) between the two rolls is preferably 0.1 to 10 mm, more preferably 0.1 to 3 mm. When the gap between the two rolls is widened, the dispersion diameter of the wax increases, and when the gap is narrowed, the dispersion diameter of the wax tends to decrease.

  Moreover, there is no limitation in particular about the structure of each roll, a magnitude | size, material, etc., The roll surface may be smooth and may be a wave type, an uneven | corrugated type, etc.

  Since the feed rate and average residence time of the raw material mixture vary depending on the size of the roll used, the composition of the raw material, and the like, optimal conditions may be selected according to these conditions. When the feed rate of the raw material is increased and the average residence time is decreased, the dispersion diameter of the wax is increased. When the supply rate of the raw material is decreased and the average residence time is increased, the dispersion diameter of the wax tends to be decreased.

  Except for the melt-kneading step using an open roll kneader, the obtained melt-kneaded product is cooled to such an extent that it can be pulverized, and then the toner of the present invention can be obtained through ordinary methods such as a pulverization step and a classification step. it can.

  In the pulverization step, it is desirable to pulverize the volume-median particle size to 20 μm or less, more preferably 10 μm or less from the viewpoint of improving durability.

  The pulverization process may be performed in multiple stages. For example, the melt-kneaded product may be coarsely pulverized to about 1 to 5 mm and further finely pulverized. Moreover, in order to improve the productivity at the time of a grinding | pulverization and a classification process, you may grind | pulverize, after mixing melt-kneaded material with inorganic fine particles, such as hydrophobic silica.

  The pulverizer used in the pulverization step is not particularly limited. For example, examples of the pulverizer suitably used for the coarse pulverization include an atomizer and a rotoplex, but a hammer mill or the like may be used. Further, examples of the pulverizer suitably used for fine pulverization include a jet mill, a collision plate mill, and a rotary mechanical mill.

  Examples of the classifier used in the classification process include an air classifier, an inertia classifier, and a sieve classifier. In the classification step, the pulverized product which has been removed due to insufficient pulverization may be subjected to the pulverization step again, and may be repeated with the pulverization step and the classification step as necessary.

After the melt-melt-kneading step, the toner particles obtained through the pulverization step and the classification step may be used as toners as they are, or external additives may be externally added to the toner particle surfaces and used as toners. The volume median particle size (D ₅₀ ) of the toner (particles) is preferably 3 to 12 μm, and more preferably 4 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.

  Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide. Among these, silica having a small specific gravity is preferable from the viewpoint of preventing embedding.

As the external additive, silica having a small specific gravity is preferable from the viewpoint of exerting a spacer effect. From the viewpoint of environmental stability, the silica is preferably hydrophobic silica that has been subjected to a hydrophobic treatment. The method for hydrophobizing is not particularly limited, and examples of the hydrophobizing agent include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, methyltriethoxysilane, and the like. The treatment amount of the hydrophobizing agent is preferably 1 to 7 mg / m ² per surface area of the inorganic fine particles.

  The content of the external additive is preferably 0.01 to 10 parts by weight and more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner particles.

  The external addition step is preferably a dry mixing method in which the external additive and toner particles are mixed using a high-speed stirrer such as a Henschel mixer or a super mixer, a V-type blender or the like. The external additives may be mixed in advance and added to a high-speed stirrer or a V-type blender, or may be added separately.

The toner of the present invention is a polyolefin wax in which a polyolefin wax is finely dispersed, and a polyolefin wax having a large dispersion diameter, that is, a domain area of 0.8 μm ² or more in cross-sectional observation using a transmission electron microscope (TEM). And, the abundance ratio of the wax auxiliary agent is preferably 0.5 area% or less in the cross-sectional area of the toner, and preferably 0.1 area% or more from the viewpoint of offset resistance.

The endothermic amount (J / g) due to the polyolefin wax in the toner is Tq, the endothermic amount (J / g) of the polyolefin wax is Wq, and the proportion of polyolefin wax in the toner raw material supplied to the open roll kneader (open roll) When the weight of the polyolefin wax supplied to the mold kneader / the weight of the toner raw material supplied to the open roll kneader is Wm, the formula (B):
Tq = Wq × Wm × X
X that satisfies the above is preferably 0.7 or more, more preferably 0.75 to 0.97, and still more preferably 0.8 to 0.95. X is a physical property indicating the ratio of the crystallized wax present in the toner (that is, the amount of wax effective for fixing). By reducing the dispersion state of the wax or increasing the speed of crystallization of the wax. The value of X can be increased. In general, the crystallization of wax and the dispersibility of wax are contradictory, and lowering the dispersibility of wax to increase X, which is a measure of crystallization of wax, results in inferior durability although fixing properties are increased. Become. However, in the present invention, by combining the polyolefin wax satisfying the formula (A) and the wax auxiliary agent, crystallization of the wax can be promoted without lowering the dispersibility of the wax, and the value of X is increased. be able to.

  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, and a 1.96 MPa load is applied by a plunger and 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 (Tg))
Using a differential scanning calorimeter (manufactured by TA Instruments Japan, DSCQ100), the sample was heated to 200 ° C and cooled to 0 ° C at a temperature decrease rate of 10 ° C / min. The temperature is raised at ° C./min, and the temperature is the intersection of the base line extension below the maximum peak temperature of endotherm and the tangent that indicates the maximum slope from the peak rise to the peak apex.

[Melting point of wax and endotherm (Wq)]
Maximum temperature of melting heat (melting point) and heat of fusion using a differential scanning calorimeter (DSCQ100, manufactured by TA Instruments Japan Co., Ltd.) while raising the temperature from 0 ° C to 200 ° C at 10 ° C / min. Measure the endothermic amount (Wq).

[Exothermic peak temperature of wax (Tc ₁ )]
Using a differential scanning calorimeter (manufactured by TA Instruments Japan, DSCQ100), the temperature is increased from 0 ° C to 200 ° C at 10 ° C / min, and from that temperature to 0 ° C at a temperature decrease rate of 10 ° C / min. with cooling, to measure the peak temperature of the highest temperature side of the exothermic peak as Tc _1.

[Exothermic peak temperature (Tc ₂ ) of a mixture obtained by mixing polyolefin wax and wax auxiliary at a weight ratio of 99/1 (polyolefin wax / wax auxiliary)]
Polyolefin wax and wax auxiliary are uniformly mixed at a weight ratio of 99/1 (polyolefin wax / wax auxiliary) (total 10 g) and mixed for 1 minute in a national coffee mill (MK-61M). The exothermic peak temperature (Tc ₂ ) of the obtained mixture is measured by the same method as the exothermic peak temperature (Tc ₁ ) of the wax.

[Wax endothermic amount (Tq) caused by polyolefin wax in toner]
In the same manner as the endothermic amount (Wq) of the wax, the endothermic amount (Tq) due to the polyolefin wax in the toner is measured using the toner as a sample.

[Volume-median particle diameter of toner (D ₅₀ )]
Measuring machine: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 50μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
Electrolyte: Isoton II (Beckman Coulter, Inc.)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) 5% electrolyte dispersion condition: 10 mg of measurement sample is added to 5 ml of dispersion, and dispersed for 1 minute with an ultrasonic disperser. Then, 25 ml of the electrolytic solution is added, and further dispersed with an ultrasonic disperser for 1 minute.
Measurement conditions: Add 100 ml of electrolyte and dispersion in a beaker, measure 30,000 particles at a concentration that can measure the particle size of 30,000 particles in 20 seconds, and determine the volume-median particle size ( determine the D _50).

Examples of resin production Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 4200 g (60), Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 2600 g ( 40), 2822 g (85) of terephthalic acid and 40 g of tin (II) 2-ethylhexylate were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer and a thermocouple. After reacting over time, it was reacted at 8.3 kPa for 1 hour. Further, 384 g (10) of trimellitic anhydride was added at 210 ° C. and reacted until the desired softening point was reached to obtain Resin A. Resin A had a softening point of 112.3 ° C. and a glass transition point of 67.3 ° C. The numerical value in parentheses after the amount of raw material monomer used indicates the molar ratio when the total amount of alcohol components is 100 mol.

Examples 1-5 and Comparative Examples 1-7 (Example 2 is a reference example)
100 parts by weight of resin A, 4 parts by weight of coloring agent (Pigment Yellow 180), 1 part by weight of negatively chargeable charge control agent “LR-147” (manufactured by Nippon Carlit), the amount of polyethylene wax (PE wax) used as shown in Table 2 “Paraflint C80” (manufactured by Schumann-Sazol, melting point: 86 ° C.) and a wax auxiliary were mixed with a Henschel mixer and melt-kneaded under the kneading conditions shown in Table 2. Details of the wax auxiliary are shown in Table 1.

[Kneading condition A]
A continuous two-roll kneader having a roll outer diameter of 0.12 m and an effective roll length of 0.8 m was used. The operating conditions of the continuous two-roll kneader were a high rotation side roll (front roll) rotation speed of 75 r / min, a low rotation side roll (back roll) rotation speed of 50 r / min, and a roll gap of 0.1 mm. The heating medium temperature and cooling medium temperature in the roll were 160 ° C. on the raw material input side of the high rotation roll and 100 ° C. on the kneading discharge side, 30 ° C. on the raw material input side of the low rotation roll, and 30 ° C. on the kneaded material discharge side. Further, the feed rate of the mixture was 4 kg / hr, and the average residence time was about 10 minutes.

[Kneading condition B]
A co-rotating twin screw extruder having a total length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm was used for kneading. The roll rotation speed was 200r / min. The heating temperature in the roll was 100 ° C., the feed rate of the mixture was 4 kg / hr, and the average residence time was about 18 seconds.

The obtained melt-kneaded product was naturally cooled and then coarsely pulverized. Further, the toner particles were pulverized and classified by a jet mill to obtain toner particles having a volume median particle size (D ₅₀ ) of 6.5 μm. It took 10 minutes for the temperature of the melt-kneaded product to drop to 25 ° C.

  To 100 parts by weight of the obtained toner particles, 1.5 parts by weight of hydrophobic silica “R-972” (manufactured by Nippon Aerosil Co., Ltd.) as an external additive was added and mixed with a Henschel mixer to obtain a toner.

The cross section of the obtained toner was observed at a magnification of 5000 with a transmission electron microscope (TEM), and the abundance ratio of polyolefin wax and / or wax auxiliary having a domain area of 0.8 μm ² or more was determined. In addition, the cross section of the toner was observed by using a TEM to prepare thin pieces each having a smooth surface from 10 toner particles using a microtome. A ratio of a value obtained by adding domain areas having a size of 0.8 μm ² or more to the total area of 10 toner flakes was calculated as the above ratio.

Test Example 1 [Crushability]
A toner crushed by attaching a mesh with a mesh opening of 3 mm to a Rotoplex, a volume median particle size (D ₅₀ ) of 6.5 μm at a grinding pressure of 0.5 Pa with an I-2 type pulverizer (manufactured by Nippon Pneumatic Co., Ltd.) And pulverization was evaluated according to the following evaluation criteria. The results are shown in Table 2. The larger the amount of pulverization per unit time, the better the pulverizability.

〔Evaluation criteria〕
A: The grinding amount per unit time is 3 kg / hr or more.
B: The pulverization amount per unit time is 1 kg / hr or more and less than 3 kg / hr.
C: The pulverization amount per unit time is less than 1 kg / hr.

Test Example 2 [Offset resistance]
The toner was mounted on the copier `` AR-505 '' (manufactured by Sharp Corporation), and an unfixed image with a toner adhesion amount of 0.5 mg / cm <sup>2</sup> and 2 cm × 12 cm was obtained, and the copier `` AR-505 '' (Sharp ( The fixing test (fixing speed 80 mm / sec) was made so that offline fixing was possible, and the fixing test was performed while gradually increasing from 90 ° C. to 240 ° C. in 5 ° C. increments. A temperature range where no offset occurs was confirmed, and offset resistance was evaluated according to the following evaluation criteria. The paper used was Fuji Xerox Office Supply Monochrome and Color Copy Paper C2 A4 V436 (70 g / m ² ). The results are shown in Table 2. The wider the non-offset region, the better the offset resistance.

〔Evaluation criteria〕
A: Non-offset region is 60 ° C or higher B: Non-offset region is 30 ° C or higher and lower than 60 ° C C: Non-offset region is lower than 30 ° C

Test Example 3 [Durability]
Toner was mounted on the non-magnetic one-component developing device “MICROLINE 703N3” (Oki Data Co., Ltd.), and 2000 charts with a printing rate of 5% were printed. Next, 5 solid images were printed, the number of vertical stripes (white spots) generated in the obtained solid image was counted, the average number per sheet was calculated, and durability was evaluated according to the following evaluation criteria . The results are shown in Table 2. It shows that durability is excellent, so that there are few vertical stripes (white blank).

〔Evaluation criteria〕
A: Less than 3 B: 3 or more, less than 10 C: 10 or more

  It can be seen that in the toners of Examples 1 to 5, the wax is finely dispersed as compared with the toners of Comparative Examples 1 to 7, and the grindability, offset resistance, and durability are all good. Among them, since there is no difference in effect between Comparative Example 3 and Comparative Example 4 using a twin screw extruder, compared with the results of Example 1 and Comparative Example 1 using an open roll type kneader, the wax auxiliary agent It is apparent that the effect obtained by blending is an effect unique to the use of an open roll kneader that cannot be obtained with a twin-screw extruder.

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

Claims (5)

An electrophotographic toner obtained by a method including a step of melt-kneading at least a binder resin, a polyolefin wax, and a wax auxiliary with an open roll type kneader,
The polyolefin wax is a polyethylene wax;
The wax aid is represented by the formula (II):

(Wherein R ² and R ³ are the same or different and are hydrocarbon groups having 1 to 6 carbon atoms)
A sorbitol compound represented by:
The content of the wax auxiliary is 10 to 30 parts by weight with respect to 100 parts by weight of the polyolefin wax,
The polyolefin wax and the wax auxiliary are represented by the formula (A):
Tc ₂ -Tc ₁ > 5.0 (A)
(In the formula, Tc ₁ is the exothermic peak temperature (° C.) of polyolefin wax by differential scanning calorimetry, and Tc ₂ is 99/1 (polyolefin wax / wax auxiliary) of polyolefin wax and wax auxiliary by differential scanning calorimetry. Exothermic peak temperature (℃) of the mixture mixed by weight ratio)
Satisfying toner for electrophotography. ^2. The electrophotography according to claim 1, wherein, in cross-sectional observation using a transmission electron microscope (TEM), the proportion of polyolefin wax and / or wax auxiliary having a domain area of 0.8 μm ² or more is 0.5 area% or less. Toner. The endothermic amount (J / g) due to the polyolefin wax in the toner is Tq, the endothermic amount (J / g) of the polyolefin wax is Wq, and the proportion of polyolefin wax in the toner raw material supplied to the open roll kneader (open roll) When the weight of the polyolefin wax supplied to the mold kneader / the weight of the toner raw material supplied to the open roll kneader is Wm, the formula (B):
Tq = Wq × Wm × X (B)
The toner for electrophotography according to claim 1, wherein X satisfying the above is 0.7 or more. The toner for electrophotography according to any one of claims 1 to 3, wherein the content of the polyolefin wax is 3 to 20 parts by weight with respect to 100 parts by weight of the binder resin. At least a binder resin, a polyolefin wax, and a wax auxiliary, a method for producing an electrophotographic toner comprising a step of melt kneading with an open roll kneader,
The polyolefin wax is a polyethylene wax;
The wax aid is represented by the formula (II):

(Wherein R ² and R ³ are the same or different and are hydrocarbon groups having 1 to 6 carbon atoms)
A sorbitol compound represented by:
The content of the wax auxiliary is 10 to 30 parts by weight with respect to 100 parts by weight of the polyolefin wax,
The polyolefin wax and the wax auxiliary are represented by the formula (A):
Tc ₂ -Tc ₁ > 5.0 (A)
(In the formula, Tc ₁ is the exothermic peak temperature (° C.) of polyolefin wax by differential scanning calorimetry, and Tc ₂ is 99/1 (polyolefin wax / wax auxiliary) of polyolefin wax and wax auxiliary by differential scanning calorimetry. Exothermic peak temperature (℃) of the mixture mixed by weight ratio)
For producing a toner for electrophotography satisfying the above.