JP2009258234A - Toner for electrophotography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide toner for electrophotography including crystalline polyester and amorphous polyester, having excellent low temperature fixability and storage stability. <P>SOLUTION: This toner for electrophotography includes binder resin. The binder resin includes crystalline polyester and amorphous polyester. When expressing the crystal growth speed in using the toner to a heating retention test by formula (A):G=G<SB>0</SB>*exp(-E/(R(Th-Tg+50)))*exp(-Ktc/(RTh(Tc-Th))), the generation energy K is 150-400 J/mol, and a factor of the number of crystal nuclei G<SB>0</SB>is 10-1,000 sec<SP>-1</SP>. <P>COPYRIGHT: (C)2010,JPO&INPIT

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.

As an attempt for low-temperature fixability, which is mentioned as a main characteristic required for the toner, a toner containing a crystalline polyester and an amorphous polyester has been studied. From the viewpoint of further improving the storage stability, a fatty acid amide compound is used. The toner to contain is reported (refer patent documents 1-3 etc.).
JP 2006-113473 A JP 2007-65620 A JP 2007-328043 A

  However, further improvements in low-temperature fixability are required with the current increase in speed. Further, since the electrophotographic technology is used in various environments, there is a demand for a toner having stable storage stability (storage stability) even in a severe environment such as a high humidity environment.

  An object of the present invention is to provide an electrophotographic toner containing a crystalline polyester and an amorphous polyester and having excellent low-temperature fixability and storage stability.

  The present invention relates to an electrophotographic toner containing a binder resin, wherein the binder resin contains a crystalline polyester and an amorphous polyester, and the toner is subjected to a heat retention test. The crystal growth rate is expressed by the formula (A):

[Wherein G is the crystal growth rate (sec ⁻¹ ), G _O is the crystal nucleus number factor (sec ⁻¹ ), E is the activation energy of molecular diffusion (J / mol), R is the gas constant [8.31 (J / mol · K)], Th is the heat holding temperature (K) of the toner, Tg is the glass transition point (K) of the toner in differential scanning calorimetry, K is the nucleation energy (J / mol), and Tc is the differential scanning calorific value. (Shows the maximum peak temperature (K) of toner endotherm in measurement.)
The nucleation energy (K) is 150 to 400 J / mol and the crystal nucleus number factor (G ₀ ) is 10 to 1000 sec ⁻¹ .

  The toner for electrophotography of the present invention contains a crystalline polyester and an amorphous polyester, and has the effect of being excellent in low-temperature fixability and storage stability.

  The electrophotographic toner of the present invention contains a crystalline polyester and an amorphous polyester as a binder resin, and the crystal growth rate when the toner is subjected to a heat retention test is expressed by the following formula (A): The nucleation energy and the crystal nucleus number factor have a great feature in that they are in a specific range. That is, the present inventors have studied in detail the relationship between the crystallinity of the binder resin and the low-temperature fixability and storage stability of the toner. In the crystal growth rate formula, it has been found that only a toner having a specific nucleation energy and a crystal nucleus number factor can achieve both low-temperature fixability and storage stability. The conditions for heating and holding the toner are as described in Examples below.

  The crystal growth rate (G) is expressed by the formula (A):

[Wherein G is the crystal growth rate (sec ⁻¹ ), G ₀ is the crystal nucleus number factor (sec ⁻¹ ), E is the molecular diffusion activation energy (J / mol), and R is the gas constant [8.31 (J / mol · K)], Th is the heat holding temperature (K) of the toner, Tg is the glass transition point (K) of the toner in differential scanning calorimetry, K is the nucleation energy (J / mol), and Tc is the differential scanning calorific value. (Shows the maximum peak temperature (K) of toner endotherm in measurement.)
The crystal growth rate equation is, for example, a formula widely used in the field of polymer science (Polymer Functional Materials Series Vol. 3 Polymer Physical Properties) Basics of the Society of Polymer Science (ed.) (See Kyoritsu Shuppan, 1993, p. 264).

Here, G ₀ is a factor relating to the number of crystal nuclei, and if G ₀ is too small, crystals are difficult to form and the filler effect is weak, so that the storage stability of the toner is poor. On the other hand, if G ₀ is too large, crystals are excessively formed, the filler effect is too strong, and the storage stability of the toner is excellent, but the low-temperature fixability is deteriorated. Therefore, from the viewpoint of achieving both storage stability and low-temperature fixability of the toner, the crystal nucleus number factor (G ₀ ) is 10 to 1000 sec ⁻¹ , preferably 10 to 450 sec ⁻¹ . Further, the nucleation energy (K) corresponds to the crystal generation energy, and the smaller the crystal, the easier the crystal is generated. However, when the crystal is excessively generated and the filler effect is too strong, the low-temperature fixability deteriorates. on the other hand. When K is too large, crystals are hardly formed and the filler effect is weak, so that the storage stability is poor. From this viewpoint, the nucleation energy (K) is 150 to 400 J / mol, preferably 200 to 400 J / mol. K and G ₀ are numerical values calculated by analysis.

  The toner of the present invention contains a crystalline polyester and an amorphous polyester as a binder resin.

  The crystallinity of the resin is expressed by the ratio between the softening point and the maximum endothermic peak temperature in the differential scanning calorimeter, that is, [softening point / maximum endothermic peak temperature]. When it is less than 0.6, the crystallinity is low and there are many amorphous parts. The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, production conditions (for example, reaction temperature, reaction time, cooling rate) and the like. In the present invention, “crystalline polyester” refers to a polyester having a [softening point / maximum endothermic peak temperature] of 0.6 to 1.5, preferably 0.8 to 1.2, and “amorphous polyester” refers to a “softening point”. / Maximum endothermic peak temperature] refers to polyesters greater than 1.5 or less than 0.6, preferably greater than 1.5. The highest endothermic peak temperature refers to the temperature of the peak on the highest temperature side among the observed endothermic peaks. If the maximum peak temperature is within 20 ° C. from the softening point, the melting point is set, and the peak having a difference from the softening point exceeding 20 ° C. is a peak due to glass transition.

  The crystalline polyester in the present invention is preferably a polyester obtained by condensation polymerization of an alcohol component containing an α, ω-linear alkanediol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound.

  Examples of the α, ω-linear alkanediol include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and the like, which increases crystallinity. From the viewpoint, a diol having 2 to 8 carbon atoms is preferable, and 1,4-butanediol and 1,6-hexanediol are more preferable.

  The content of α, ω-linear alkanediol is preferably 90 to 100 mol%, more preferably 95 to 100 mol%, in the alcohol component, from the viewpoint of enhancing crystallinity.

  Aliphatic dicarboxylic acid compounds 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. Examples thereof include aliphatic dicarboxylic acids such as acids, anhydrides of these acids, alkyl (C1-3) esters, etc. Among these, dicarboxylic acid compounds having 2 to 8 carbons are preferable, and fumaric acid is more preferable. preferable. As described above, the aliphatic dicarboxylic compound refers to an aliphatic dicarboxylic acid, its anhydride, and its alkyl (C1-3) ester. Among these, an aliphatic dicarboxylic acid is preferable.

  The content of the aliphatic dicarboxylic acid compound is preferably 90 to 100 mol%, more preferably 95 to 100 mol% in the carboxylic acid component, from the viewpoint of enhancing crystallinity.

  The molar ratio of the aliphatic dicarboxylic acid compound to the α, ω-linear alkanediol in the crystalline polyester (aliphatic dicarboxylic acid compound / α, ω-linear alkanediol) is further determined from the viewpoint of production stability. When the amount of ω-linear alkanediol is large, it is preferably 0.9 or more and 1.0 or less, more preferably 0.95 or more and 1.0 or less, from the viewpoint that the molecular weight of the resin can be easily adjusted by evaporation during a vacuum reaction.

  Crystalline polyester is obtained by condensation polymerization of an alcohol component and a carboxylic acid component at a temperature of 120 to 230 ° C. in an inert gas atmosphere, if necessary, using an esterification catalyst, a polymerization inhibitor, etc. can get. Specifically, all monomers are charged at once to increase the strength of the resin, or a divalent monomer is first reacted to reduce low molecular weight components, and then a trivalent or higher monomer. A method of adding and reacting may be used. Further, the reaction may be accelerated by reducing the pressure of the reaction system in the latter half of the polymerization. In order to obtain polyester with high crystallinity, it is preferable to increase the molecular weight, and it is more preferable to carry out the reaction until the viscosity of the reaction solution becomes high.

  The number average molecular weight of the crystalline polyester is preferably 2000 to 4000, more preferably 2200 to 3500, and further preferably 2300 to 3000, from the viewpoint of storage stability and productivity of the toner. When using an aliphatic alcohol, 6000 to 9000 is preferable from the viewpoint of hot offset resistance of the toner.

  The maximum endothermic peak temperature by differential scanning calorimetry of the crystalline polyester is preferably from 110 to 140 ° C, more preferably from 110 to 130 ° C, more preferably from 110 to 120 ° C, from the viewpoints of low-temperature fixability, storage stability and durability of the toner. More preferably.

  The softening point of the crystalline polyester is preferably from 70 to 140 ° C, more preferably from 90 to 130 ° C, and even more preferably from 90 to 120 ° C, from the viewpoint of low-temperature fixability of the toner. Examples of the method of adjusting the softening point include a method of adjusting the molar ratio of the aliphatic dicarboxylic acid compound and the α, ω-linear alkanediol, a reaction temperature, an amount of the catalyst, and a dehydration reaction for a long time under reduced pressure. The method of changing the reaction conditions of esterification is mentioned. Specifically, the number average molecular weight can be increased by increasing the proportion of the aliphatic dicarboxylic acid compound, increasing the reaction temperature, increasing the amount of catalyst, extending the dehydration reaction time, or the like. Further, if the above description is reversed, there is a tendency to become smaller. In addition, as described above, in order to adjust the ratio between the softening point and the maximum endothermic peak temperature, the molar ratio of the aliphatic dicarboxylic acid compound and the α, ω-linear alkanediol is adjusted, or the reaction temperature is increased. This can be achieved by adjusting the reaction conditions such as increasing the amount, performing dehydration reaction for a long time under reduced pressure.

  As the alcohol component of the amorphous polyester, the formula (I):

(In the formula, R ¹ O and OR ¹ are oxyalkylene groups, R ¹ is an ethylene and / or propylene group, x and y indicate the number of added moles of alkylene oxide, and each is a positive number; The average value of the sum of y and y is preferably 1 to 16, more preferably 1 to 8, and even more preferably 1.5 to 4)
An alkylene oxide adduct of bisphenol A represented by the formula: ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4- Examples include diols such as butenediol, 1,5-pentanediol, and 1,6-hexanediol, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, trimethylolpropane, and the like.

  Among these, an alkylene oxide adduct of bisphenol A represented by the formula (I) is preferable from the viewpoint of polyester amorphization and toner chargeability and durability. The content of the alkylene oxide adduct of bisphenol A is preferably 50 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol% or more in the alcohol component.

  Dicarboxylic acid compounds contained in the carboxylic acid component include fumaric acid, adipic acid, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, sebacic acid, azelaic acid, n- Aliphatic dicarboxylic acids having 2 to 30 carbon atoms, preferably 2 to 8 carbon atoms such as dodecyl succinic acid and n-dodecenyl succinic acid; Aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid; Dicarboxylic acids; anhydrides of these acids; and alkyl (C1-3) esters of acids. Among these, from the viewpoint of low-temperature fixability of the toner, an aliphatic dicarboxylic acid compound is preferable, and fumaric acid is more preferable.

  The content of the aliphatic dicarboxylic acid compound is preferably 40 to 90 mol%, more preferably 50 to 85 mol% in the carboxylic acid component.

  In addition, trivalent or higher polyvalent carboxylic acid compounds include trimellitic or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid, anhydrides of these acids, and alkyl alkyls (1 to 3 carbon atoms). Examples include esters.

  From the viewpoint of hot offset resistance of the toner, the content of the trivalent or higher polyvalent carboxylic acid compound is preferably 10 to 50 mol%, more preferably 15 to 30 mol%, in the carboxylic acid component.

  A monovalent alcohol may be appropriately contained in the alcohol component, and a monovalent carboxylic acid compound may be appropriately contained in the carboxylic acid component for molecular weight adjustment or the like.

  The condensation polymerization of the alcohol component and the carboxylic acid component in the amorphous polyester can be performed, for example, in an inert gas atmosphere at a temperature of 180 to 250 ° C., but the effect of the present invention is more remarkably exhibited. From the viewpoint of production, it is preferably carried out in the presence of an esterification catalyst such as dibutyltin oxide and tin (II) octylate.

  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 amorphous polyester is preferably from 100 to 170 ° C., more preferably from 120 to 150 ° C., from the viewpoints of low-temperature fixability and hot offset resistance of the toner.

  The glass transition point of the amorphous polyester is preferably 40 to 70 ° C, more preferably 50 to 70 ° C, from the viewpoints of low-temperature fixability and durability of the toner. The acid value is preferably 5 to 60 mgKOH / g, more preferably 10 to 30 mgKOH / g.

  The number average molecular weight of the amorphous polyester is preferably 2000 to 4000, more preferably 2300 to 3500, from the viewpoint of hot offset resistance of the toner.

  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.

  In the present invention, the binder resin contains a crystalline polyester and an amorphous polyester as main components, but the content of the crystalline polyester is 5% in the binder resin from the viewpoint of low-temperature fixability and durability of the toner. -40% by weight is preferred, 5-35% by weight is more preferred, and 15-30% by weight is even more preferred.

  The content of the amorphous polyester is preferably 60 to 99% by weight, more preferably 65 to 95% by weight, and more preferably 70 to 85% by weight in the binder resin from the viewpoint of low-temperature fixability and durability of the toner. .

  The weight ratio of crystalline polyester to amorphous polyester (crystalline polyester / amorphous polyester) is preferably 5/95 to 40/60, from the viewpoint of low-temperature fixability and durability of the toner, and 15/85 to 30 / 70 is more preferable.

  In the binder resin in the present invention, in addition to the crystalline polyester and the amorphous polyester, other binder resins may be appropriately contained as long as the effects of the present invention are not impaired. Examples of other binder resins include binder resins other than polyesters such as vinyl resins, epoxy resins, polycarbonates, and polyurethanes. The total content of the crystalline polyester and the amorphous polyester is not particularly limited, but is preferably 95% by weight or more and more preferably 99% by weight or more in the binder resin from the viewpoint of low-temperature fixability of the toner.

  The softening point of the binder resin is preferably from 80 to 170 ° C, more preferably from 100 to 160 ° C, from the viewpoint of low-temperature fixability and storage stability of the toner. In the present invention, the softening point of the binder resin is a weighted average value obtained by multiplying the physical properties of the resin constituting the binder resin by the resin content.

  Further, as a toner raw material other than the binder resin in the present invention, a colorant, a release agent, a charge control agent, a magnetic powder, a conductivity adjusting agent, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, an aging Additives such as an inhibitor, a fluidity improver, and a cleanability improver may be used 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 alone or in combination of two or more. Any of black toner, color toner, and full color toner may be used. The content of the colorant is preferably 1 to 40 parts by weight and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  As release agents, natural waxes such as polypropylene wax, polyethylene wax, synthetic wax such as Fischer Tropu, coal wax such as montan wax, petroleum wax such as paraffin wax, wax such as alcohol wax, carnauba wax and rice wax An ester wax may be mentioned, and these waxes may be used alone or in admixture of two or more. The content of the release agent is preferably 1 to 20 parts by weight and more preferably 2 to 10 parts by weight with respect to 100 parts by weight of the binder resin from the viewpoint of toner fixing properties.

  The charge control agent may be either a positively chargeable charge control agent or a negatively chargeable charge control agent, and these may be used in combination. Examples of the positively chargeable charge control agent include digrosine dyes, triphenylmethane dyes containing tertiary amines as side chains, quaternary ammonium salt compounds, polyamine resins, and imidazole derivatives. Examples of the negatively chargeable charge control agent include metal-containing azo dyes, metal complexes of alkyl derivatives of salicylic acid, and boron complexes of benzyl acid. The content of the charge control agent is preferably 0.1 to 5.0 parts by weight and more preferably 0.2 to 4.0 parts by weight with respect to 100 parts by weight of the binder resin from the viewpoint of toner chargeability.

  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.

  Therefore, the toner of the present invention is preferably produced by a method including a step of melt-kneading a toner raw material containing a binder resin and a step of pulverizing the obtained kneaded product.

  Melting and kneading of the toner material can be performed using a known kneader such as a closed kneader, a single or twin screw extruder, and an open roll kneader. It is preferable that the binder resin and the toner raw materials such as a colorant, a release agent, and a charge control agent used as needed are mixed in advance using a Henschel mixer, a super mixer, etc., and then subjected to melt kneading.

  After melt-kneading, the obtained kneaded material is cooled until reaching a pulverizable hardness, and is subjected to a pulverization step.

  The pulverization process may be performed in multiple stages. For example, the kneaded product may be coarsely pulverized to about 1 to 5 mm, and then finely pulverized to a desired particle size.

  The pulverizer used in the pulverization step is not particularly limited. For example, as a pulverizer suitably used for coarse pulverization, an atomizer, a rotoplex, etc., as a pulverizer suitably used for fine pulverization, a jet mill, a collision Examples thereof include a plate mill and a rotary machine mill.

  After the pulverization step, it is preferable to adjust the particle size of the toner by appropriately performing a classification step, a sieving step, and the like.

  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 that has been removed due to insufficient pulverization may be subjected to the pulverization step again.

  Although the toner is obtained by the above steps, inorganic fine particles such as hydrophobic silica and resin fine particles may be externally added to the obtained toner surface.

The volume median particle size (D ₅₀ ) of the toner of the present invention is preferably 2 to 15 μm, more preferably 3 to 10 μm, and even more preferably 3 to 9 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 obtained by the above method. In the present invention, examples of the means for adjusting G ₀ and K include the following methods (a) to (f).

(a) By using an aromatic amide compound as a toner raw material, G ₀ increases, K decreases, and by increasing its dispersibility, G ₀ tends to increase further.

By using an aromatic amide compound serving as a crystal nucleating agent as a toner raw material, crystals are easily precipitated, and G ₀ is increased by increasing the dispersibility of the aromatic amide compound in the toner. If the addition amount of the aromatic amide compound is the same, K is hardly changed even if the dispersibility is changed.

As the aromatic amide compound, the formula (II):
^{R 2 -CONH-X-NHCO-} R 3 (II)
(In the formula, R ² and R ³ are the same or different, and the cycloalkyl group having 5 to 12 carbon atoms, X is the formula (IIa):

Or formula (IIb):

Is a group represented by
The compound represented by these is preferable. The aromatic amide compound represented by the formula (II) has one or more aromatic rings between two amide bonds, and this specific aromatic amide compound, a crystalline polyester and an amorphous polyester, By this interaction, it is presumed that the aromatic ring and the crystalline polyester structure are regularly arranged (causes stacking), and the crystallization of the crystalline polyester is likely to occur.

  Specific examples of the aromatic amide compound represented by the formula (II) include N, N′-dicyclohexyl-2,6-naphthalenedicarboxamide, N, N′-dicyclooctyl-2,6-naphthalenedicarboxamide, N, N′-dicyclododecyl-2,6-naphthalenedicarboxamide, N, N′-dicyclohexyl-4,4′-biphenyldicarboxamide and the like can be mentioned.

  The content of the aromatic amide compound represented by the formula (II) is preferably 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the binder resin, from the viewpoint of low-temperature fixability and storage stability of the toner, 3.0 parts by weight is more preferable, and 1.0 to 2.0 parts by weight is even more preferable.

As a means for improving the dispersibility of the aromatic amide compound in the toner,
(a1) a method of adding an aromatic amide compound to the reaction system during the production of the crystalline polyester,
(a2) The toner raw material melt-kneading step includes a first kneading step of melt-kneading the toner raw material containing the amorphous polyester and the aromatic amide compound, and the kneaded product obtained in this step and the crystalline polyester A method in which the toner material is melted and kneaded in two stages of the second kneading step,
(a3) A method using a kneader having a higher kneading share, for example, the above-described open roll type kneader, may be used for melt kneading of the toner raw material.

  In the method (a1), the aromatic amide compound has a reaction rate (ratio of measured effluent to theoretical effluent) of 90% after reacting raw material monomers in the presence of a catalyst from the viewpoint of increasing share and increasing dispersibility. It is preferable to add it to the reaction system when it becomes at least%. In this case, the compounding amount of the aromatic amide compound is preferably 1.0 to 10 parts by weight with respect to 100 parts by weight of the total amount of the raw material monomers for the crystalline polyester.

  In the method (a2), the compounding amount of the aromatic amide compound is preferably 10 to 50 parts by weight, more preferably 15 to 40 parts by weight, and further 20 to 30 parts by weight with respect to 100 parts by weight of the amorphous polyester. preferable.

  The kneader used in the first kneading step and the second kneading step is not particularly limited. However, in the first kneading step, it is preferable to use a kneader having a high kneading share such as a uniaxial or biaxial extruder.

  Additives such as colorants and charge control agents may be blended in any of the first kneading step and the second kneading step, and further the third kneading step of blending these additives after the second kneading step. However, it is preferable to blend in the second kneading step from the viewpoint of production efficiency.

  Examples of the kneader having a higher kneading share used in the method (a3) include an open roll type kneader.

  The open roll type kneader was provided along the axial direction of the roll because the additive can be efficiently and highly dispersed in the binder resin without repeating kneading or using a dispersion aid. It is preferable to use a continuous open roll type kneader equipped with a supply port and a kneaded product discharge port.

  The toner raw material is preferably mixed in advance using a Henschel mixer, a super mixer, etc., and then supplied to an open roll type kneader, and may be supplied to the kneader from one supply port. However, from the viewpoint of ease of operation and simplification of the apparatus, it is preferable to supply the kneader from one supply port.

  The continuous open roll type kneader means an open type kneading part, and can easily dissipate the kneading heat generated during kneading. Further, the continuous open roll type kneader is preferably a kneader equipped with at least two rolls, and the continuous open roll type kneader used in the present invention comprises two rolls having different peripheral speeds, That is, the kneading machine includes 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 raw material charging side end temperature of the high rotation side roll is preferably 100 to 160 ° C, and the raw material charging side end temperature of the low rotation side roll is preferably 35 to 100 ° C.

  In the high rotation side roll and the low rotation side roll, the difference in set temperature between the raw material charging side end and the kneaded product discharge side end is preferably 0 to 50 ° C. from the viewpoint of the dispersibility of the additive, 0 More preferably, it is -40 degreeC, and it is still more preferable that it is 0-20 degreeC.

  The peripheral speed of the high rotation side roll is preferably 2 to 100 m / min, and more preferably 4 to 50 m / min. The peripheral speed of the low rotation side roll is preferably 1 to 90 m / min, more preferably 2 to 60 m / min, and further preferably 2 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.

  The structure, size, material, etc. of the roll are not particularly limited, and the roll surface may be any of smooth, corrugated, uneven, etc., but in order to increase the kneading share, a plurality of roll surfaces are provided on the surface of each roll. It is preferable that the spiral groove is cut.

(b) Increasing the molecular weight of the crystalline polyester increases G ₀ and K.

  As a means of increasing the molecular weight of the crystalline polyester, in order to obtain a high molecular weight polyester having a high molecular weight, the molar ratio of the aliphatic dicarboxylic acid compound and the α, ω-linear alkanediol is adjusted as described above. The reaction conditions may be selected such as increasing the reaction temperature, increasing the amount of catalyst, or performing a dehydration reaction for a long time under reduced pressure. A high-power motor can be used to produce a high-molecular-weight polyester having a high molecular weight. However, when the production equipment is not particularly selected, the raw material monomer is a non-reactive low-viscosity resin. A method of reacting with a solvent is also an effective means.

(c) K is reduced by using an aliphatic alcohol as the alcohol component of the amorphous polyester.

  The aliphatic alcohol is preferably a branched aliphatic diol such as ethylene glycol, neopentyl glycol, or 1,2-propanediol from the viewpoint of enhancing amorphization. The content of the aliphatic alcohol is preferably 50 mol% or more, more preferably 70 mol% or more in the alcohol component.

  When an aliphatic alcohol is used as the alcohol component of the amorphous polyester, it is preferable to use an aromatic carboxylic acid compound from the viewpoint of enhancing the amorphous property of the resulting polyester. The content of the aromatic carboxylic acid compound is preferably 50 mol% or more, more preferably 70 mol% or more in the carboxylic acid component.

  When an aliphatic alcohol is used as the amorphous polyester alcohol component, it is preferably used in combination with a crystalline polyester having a high number average molecular weight, specifically a number average molecular weight of 6000 to 9000.

(d) By dispersing an amide compound serving as a crystal nucleating agent in the crystalline polyester, preferably an amide compound having a molecular weight of 1000 or less having 3 or more amide bonds, G ₀ increases and K decreases.

  The amide compound having a molecular weight of 1000 or less and having 3 or more amide bonds has 3 or more, preferably 3 to 6, more preferably 4 to 5 amide bonds from the viewpoint of chemical interaction with the polyester. It is desirable that the molecular weight is 1000 or less, preferably 200 to 600. Note that three or more amide bonds do not need to be linked, and each may exist alone.

  The amide compound is preferably an amide compound having an aromatic ring from the viewpoint of toner charge stability. By having an aromatic ring, it is considered that the charge is structurally easily retained, and the charging stability of the toner is further improved.

  These specific compounds include those of formula (IIIa):

(Molecular weight: 438)
An aromatic amide compound represented by formula (IIIb):

(Molecular weight: 414)
An aromatic amide compound represented by formula (IIIc):

(Molecular weight: 382)
An aromatic amide compound represented by formula (IIId):

(Molecular weight: 442)
And compounds having a structure in which two amide bonds are adjacent, such as an aromatic amide compound represented by the formula: These compounds are thought to form hydrogen bonds with the crystalline polyester, which is presumed to improve the storage stability and charging stability of the toner. From the viewpoint, an aromatic amide compound represented by the formula (IIIa), that is, bis (2-benzoylhydrazine) sebacate is preferable.

  The amide compound having a molecular weight of 1000 or less and having 3 or more amide bonds is reacted with the raw material monomer in the presence of a catalyst from the viewpoint of increasing the share and dispersibility, and then the reaction rate (measured effluent relative to the theoretical effluent is measured). When the ratio is 90% or more, it is preferably added to the reaction system. In this case, the compounding amount of the amide compound is preferably 1.0 to 10 parts by weight with respect to 100 parts by weight of the total amount of the raw material monomers for the crystalline polyester.

(e) By using talc as a crystal nucleating agent as a toner raw material, G ₀ increases and K decreases.

  The number average particle diameter of talc is preferably 50 nm to 3 μm, more preferably 0.1 to 1.5 μm, from the viewpoint of dispersibility in the toner.

  The blending amount of talc is preferably 0.1 parts by weight or more and less than 1.0 part by weight with respect to 100 parts by weight of the binder resin.

(f) In a toner that does not use a copper pigment as a colorant, G ₀ increases and K decreases by dispersing a copper pigment serving as a crystal nucleating agent in a crystalline polyester.

  As the copper pigment, a copper phthalocyanine pigment is preferable.

  Copper pigments are added to the reaction system when the reaction rate (the ratio of measured effluent water to theoretical effluent water) is 90% or more after reacting raw material monomers in the presence of a catalyst from the viewpoint of improving dispersibility. It is preferable to add. In this case, the compounding amount of the copper pigment is preferably 0.1 to 10 parts by weight, and more preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the total amount of the raw material monomers for the crystalline polyester.

On the other hand, as a method of reducing G ₀ , the reverse of the above description may be taken. That is, a method of deteriorating the dispersion state of the crystal nucleating agent can be mentioned. Moreover, as a method of increasing K, there is an increase in the molecular weight of the crystalline polyester.

  The toner obtained by the present invention can be used for both a one-component developing toner and a two-component developing toner used by mixing with a carrier, but as a one-component developing toner that requires more heat resistance. More preferably used.

[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. While applying a load of 1.96 MPa with a plunger and 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 of the sample flows out.

[Maximum peak temperature of resin endotherm]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the sample cooled from room temperature to 0 ° C at a temperature drop rate of 10 ° C / min is allowed to stand still for 1 minute, and then measured at a temperature rise rate of 10 ° C / min. . Among the observed endothermic peaks, the temperature of the peak on the highest temperature side is defined as the highest endothermic peak temperature. If the maximum peak temperature is within 20 ° C. from the softening point, the melting point is set, and the peak having a difference from the softening point exceeding 20 ° C. is a peak due to glass transition.

[Glass transition point of resin and toner]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the sample was heated to 200 ° C at a heating rate of 10 ° C / min and cooled to -10 ° C at a cooling rate of 100 ° C / min for 3 minutes. Thereafter, the temperature is raised to 25 ° C. at a temperature rising rate of 60 ° C./min, held for 2 minutes, and measurement is started at a temperature rising rate of 10 ° C./min. The glass transition point is defined as the temperature at the intersection of the base line extension below the glass transition point and the tangent that indicates the maximum slope from the peak rising portion to the peak apex.

[Maximum peak temperature of toner endotherm (Tc)]
Using a differential scanning calorimeter (DSC210, manufactured by Seiko Denshi Kogyo Co., Ltd.), the sample cooled from room temperature to 0 ° C. at a cooling rate of 10 ° C./min was allowed to stand for 1 minute, and then 160 ° C. at a heating rate of 10 ° C./min. Raise the temperature to 0 ° C and cool to 0 ° C at a rate of 10 ° C / min. Allow to stand at 0 ° C for 2 minutes, then measure at a heating rate of 10 ° C / min. Among the observed endothermic peaks, the temperature of the peak on the highest temperature side is defined as the highest endothermic peak temperature.

[Resin acid value]
Measured by 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)).

[Number average molecular weight of resin]
The number average molecular weight is obtained from a chart showing the molecular weight distribution by gel permeation chromatography obtained by the following method.
(1) Preparation of sample solution Amorphous polyester is dissolved in tetrahydrofuran and crystalline polyester is dissolved in chloroform so that the concentration is 0.5 g / 100 mL. Next, this solution is filtered using a fluororesin filter (FP-200, manufactured by Sumitomo Electric Industries, Ltd.) having a pore size of 2 μm to remove insoluble components, thereby obtaining a sample solution.
(2) Molecular weight distribution measurement Using the following measuring apparatus and analytical column, tetrahydrofuran was flown at a flow rate of 1 mL / min for measurement of amorphous polyester as a solution, and chloroform was measured at a flow rate of 1 mL / min for measurement of crystalline polyester. Stabilize the column in a thermostat. Measurement is performed by injecting 100 μL of the sample solution. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. In this calibration curve, there are several types of monodisperse polystyrene (2.63 × 10 ³ , 2.06 × 10 ⁴ , 1.02 × 10 ⁵ , manufactured by Tosoh Corporation, 2.10 × 10 ³ , 7.00 × 10 ³ , 5.04 × manufactured by GL Sciences, Inc. Use 10 ⁴ ) prepared as a standard sample.
Measuring device: CO-8010 (manufactured by Tosoh Corporation)
Analytical column: GMHXL + G3000HXL (manufactured by Tosoh Corporation)

[Number average particle diameter of talc]
Using a laser diffraction particle size analyzer (HORIBA, LA-920), distilled water is added to the measurement cell, and the number average particle size is measured at a concentration where the absorbance is in the proper range.

[Volume-median particle size of toner (D ₅₀ )]
In this specification, the volume-median particle size (D ₅₀ ) of the toner means the particle size of the toner in which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size.
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) 5% by weight Electrolyte dispersion condition: 10 mg of measurement sample was added to 5 mL of dispersion, and dispersed for 1 minute with an ultrasonic disperser. Thereafter, 25 mL of an electrolytic solution is added, and further dispersed with an ultrasonic disperser for 1 minute.
Measurement conditions: The dispersion is added to 100 mL of the electrolytic solution so that the particle size of 30,000 toner particles can be measured in 20 seconds, and 30,000 particles are measured. Determine the median particle size (D ₅₀ ).

Production Example 1 of Crystalline Polyester
Raw material monomers shown in Table 1, 8 g of tin (II) octylate (0.5 parts by weight based on 100 parts by weight of the total amount of alcohol and carboxylic acid components) and 1 g of t-butylcatechol (TBC) (of alcohol and carboxylic acid components) (0.05 parts by weight with respect to 100 parts by weight in total) was placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, dehydration tube, stirrer and thermocouple, and reacted at 160 ° C. for 5 hours. The temperature was raised to 200 ° C. and reacted for 1 hour. Further, the reaction was carried out at 8.3 kPa for 3 hours to obtain a resin a.

Production Example 2 of Crystalline Polyester
Raw material monomer shown in Table 1 and 1 g of t-butylcatechol (TBC) (0.05 parts by weight with respect to 100 parts by weight of the total amount of alcohol component and carboxylic acid component) are equipped with a nitrogen introduction tube, dehydration tube, stirrer and thermocouple. In a 5-liter four-necked flask, reacted at 160 ° C for 5 hours, heated to 200 ° C, and 8 g of tin (II) octylate (total amount of alcohol and carboxylic acid components of 100 wt. 0.5 part by weight) was further added and reacted at 8.3 kPa for 3 hours to obtain Resin b.

Production Example 3 of Crystalline Polyester
Raw material monomers shown in Table 1, 8 g of tin (II) octylate (0.5 parts by weight based on 100 parts by weight of the total amount of alcohol and carboxylic acid components) and 1 g of t-butylcatechol (TBC) (of alcohol and carboxylic acid components) (0.05 parts by weight with respect to 100 parts by weight in total) was put into a 5-liter four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer and thermocouple, and reacted at 160 ° C. for 5 hours. When the ratio of the measured effluent to the theoretical effluent reached 90% or more, the crystal nucleating agents shown in Table 1 were added respectively. Then, it heated up at 200 degreeC, was made to react for 1 hour, and was made to react at 8.3 kPa for 3 hours, and resin cf was obtained.

Production Example 1 of Amorphous Polyester
Raw material monomers other than trimellitic anhydride shown in Table 2, 10 g of tin (II) octylate (0.5 parts by weight with respect to 100 parts by weight of the total amount of alcohol component and carboxylic acid component) and 1 g of t-butylcatechol (TBC) (alcohol) 0.05 parts by weight with respect to 100 parts by weight of the total amount of components and carboxylic acid components) is placed in a 5-liter four-necked flask equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer, and a thermocouple. And then reacted at 8.3 kPa for 1 hour. Further, trimellitic anhydride shown in Table 2 was added and reacted at normal pressure (101.3 kPa) for 1 hour, and then reacted at 40 kPa until the desired softening point was reached, to obtain Resin A.

Production Example 2 of Amorphous Polyester
A reflux condenser tube in which raw material monomers other than trimellitic anhydride shown in Table 2 and tin (II) octylate 10 g (0.5 parts by weight with respect to 100 parts by weight of the total amount of alcohol component and carboxylic acid component) were passed through cold water at room temperature. In a 5-liter four-necked flask equipped with a distillation tube, nitrogen introduction tube, dehydration tube, stirrer, and thermocouple with 98 ° C warm water at the top, and at 230 ° C under a nitrogen atmosphere The reaction was allowed to take 8 hours. Further, trimellitic anhydride shown in Table 2 was added at 210 ° C., reacted at normal pressure (101.3 kPa) for 1 hour, and reacted at 40 kPa until the desired softening point was reached to obtain resin B. It was.

Examples 1-4, 6-11 and Comparative Examples 1-5
Binder resin consisting of the resins shown in Table 3 100 parts by weight, Carnauba wax No. 1 (manufactured by Kato Yoko) 2.0 parts by weight, carbon black “Regal 330” (manufactured by Cabot) 4.0 parts by weight, charge control agent “T-77” “0.5 parts by weight (manufactured by Hodogaya Chemical Co., Ltd.) and the crystal nucleating agent shown in Table 3 were sufficiently mixed with a Henschel mixer, and then sufficiently mixed with a Henschel mixer. After mixing, the mixture was melt-kneaded under the kneading conditions shown in Table 3.

[Kneading condition A]
The kneaded portion was melt kneaded using a co-rotating twin screw extruder (Ikegai Iron Works, PCM-30-30) having a total length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm. The barrel set temperature was 90 ° C. (kneading temperature 125 to 140 ° C.), the screw rotation speed was 200 r / min, the mixture supply speed was 10 kg / hour, and the average residence time was about 18 seconds.

[Kneading condition B]
Using a subtractive screw feeder, the roll end at a feed rate of 10 kg / h into a continuous two-open roll kneader “NIDEX” (Mitsui Mining Co., Ltd., roll outer diameter: 14 cm, effective roll length: 80 cm) From about 10 cm from the raw material input port. The operating conditions of the kneader are: the front roll speed is 75 r / min (circumferential speed: 32.97 m / min), the rear roll speed is 50 r / min (peripheral speed: 21.98 m / min), and the heating medium for the front roll The temperature is set to 100 ° C on the upstream side of the kneading, 85 ° C on the downstream side, and the cooling medium temperature of the rear roll is set to 35 ° C on both the upstream and downstream sides of the kneading, and the two rolls are arranged in parallel. The gap was 0.1 mm.

The obtained kneaded product is cooled and coarsely pulverized, then pulverized and classified by an I-2 type pulverizer (manufactured by Nippon Pneumatic Co., Ltd.), and classified to toner particles having a volume median particle size (D ₅₀ ) of 8.5 μm ( Classification) was obtained.

  To 100 parts by weight of the obtained toner particles (classified product), 0.65 parts by weight of hydrophobic silica “TS-530” (manufactured by Cabot) is added as an external additive, and mixed with a Henschel mixer, to thereby add toner. Obtained.

Example 5
80 parts by weight of resin A and 20 parts by weight of amide compound A as a crystal nucleating agent are sufficiently mixed with a Henschel mixer, and then set at a set temperature of 150 ° C. with a single screw extruder Labo Plast Mill (Toyo Seiki Seisakusho, type 30C150). Screw rotation: melt kneading for 10 minutes at 50 r / min (first kneading step).

  Kneaded material consisting of 4 parts by weight of resin A and 1 part by weight of amide compound A, 76 parts by weight of resin A, 20 parts by weight of resin a, 2.0 parts by weight of Carnauba wax 1 (manufactured by Kato Yoko Co., Ltd.), carbon black “ Regal 330 "(Cabot) 4.0 parts by weight and charge control agent" T-77 "(Hodogaya Chemical Co., Ltd.) 0.5 parts by weight were kneaded under kneading conditions A (second kneading step), and thereafter In the same manner as in Example 1, a toner was obtained.

[Analysis of crystal growth rate (G)]
The toners obtained in Examples and Comparative Examples were subjected to a heating and holding test by the following method, and the crystal growth rate (G) at that time was analyzed. The results are shown in Table 3.

(1) Heat retention test The sample (toner) was set in a rheometer (ARES, TA Instruments) cell, melted at 160 ° C for 5 minutes, and then cooled to 50 ° C at 20 ° C / min. Thereafter, it is heated and held at the same temperature for 20 hours. During the heating and holding, the storage elastic modulus (G ′) is measured with a rheometer (Strain: 0.05%, frequency: 6.28 rad / sec). Similarly, after cooling at 60 ° C., 70 ° C., 80 ° C., and 90 ° C. at 20 ° C./min, the temperature is maintained for 20 hours.

(2) Measurement of crystal growth rate (G) G ′ at time (t ₀ ) at which heating is started is 0, and G ′ is 1 at time (t _end ) after 20 hours at the predetermined temperature. , the change in G 'from t ₀ to t _end represented by 0 and 1. This is standardized as G ′.

The time until the value normalized at the heated holding temperature Th (50 ° C.) reaches 0.5 is defined as a half crystallization time (t _50half ). The reciprocal of t _50half is defined as the crystal growth rate G with respect to the heating and holding temperature Th (50 ° C.). Similarly, when the heating holding temperature Th is 60 ° C., 70 ° C., 80 ° C., and 90 ° C., the corresponding crystal growth rate G at each heating holding temperature Th is obtained.

(3) Calculation of K and G _{0 at} the crystal growth rate G represented by the formula (A)
(3-a) Formula (A):

[Wherein G is the crystal growth rate (sec ⁻¹ ), G ₀ is the crystal nucleus number factor (sec ⁻¹ ), E is the molecular diffusion activation energy (J / mol), and R is the gas constant [8.31 (J / mol · K)], Th is the heat holding temperature (K) of the toner, Tg is the glass transition point (K) of the toner in differential scanning calorimetry, K is the nucleation energy (J / mol), and Tc is the differential scanning calorific value. (Shows the maximum peak temperature (K) of toner endotherm in measurement.)
Is regarded as a function of the heating and holding temperature Th, and is converted into an ln formula represented by the following formula (B).

(3-b) A term including E (segment diffusion rate term) is set as A, and equation (B) is further transformed into the following equation (C).

(3-c) lnG-lnA is the y-axis, Tc / RTh (Tc-Th) is the x-axis, lnG-lnA is regarded as a function of Th, and the crystal growth rate G corresponding to each heating holding time Th is substituted. . And the value of E when the slope R2 (correlation coefficient) is the highest in the value of lnG-lnA (y-axis) and the horizontal axis (x-axis) (defined as molecular diffusion activation energy (E)) Is determined according to the method described in Journal of Applied Polymer Science, Vol. 91, p. 3595 (2004), Macromolecules 2003, 36, p.

(3-d) In the obtained linear relationship equation, the slope is the nucleation energy (K) necessary for nucleation, and the y-intercept is the logarithm of the crystal nuclei factor (G ₀ ), and K and G ₀ are calculated. be able to.

Test Example 1 [low temperature fixability]
Full-color image forming apparatus of a non-magnetic one-component developing method "MICROLINE 5400" implements toner (Oki Data Corporation), solid image of 2 cm × 12cm in standard developing bias (toner amount: 0.5 mg / cm ²⁾ An unfixed image having was obtained. Using a fixing machine (fixing speed: 100 mm / sec) of the copier “AR-505” (manufactured by Sharp), which has been modified to enable fixing outside the machine, the fixing temperature is increased from 90 ° C to 180 ° C to 5 ° C. The unfixed image was fixed while gradually increasing.

“Unicelohan tape” (Mitsubishi Pencil Co., Ltd., width: 18 mm, JIS Z-1522) was pasted on the fixed image, passed through a fixing roller set at 30 ° C., and then the tape was peeled off. The optical reflection density of the solid image before and after the tape was peeled off was measured using a reflection densitometer “RD-915” (manufactured by Macbeth). The fixing temperature exceeding 70% was regarded as the lowest fixing temperature, and the low temperature fixing property was evaluated. The results are shown in Table 3. The lower the minimum fixing temperature, the better the low-temperature fixing property. The paper used for the fixing test is “CopyBond SF-70NA” (manufactured by Sharp Corporation, 75 g / m ² ).

Test Example 2 [storage stability]
4 g of toner was placed in a 20 mL polybin and left in an environment at a temperature of 55 ° C. for 48 hours. After standing, the aggregation degree of the toner was measured with a powder tester (manufactured by Hosokawa Micron Corporation) by the following method to evaluate the storage stability. The results are shown in Table 3. The lower the degree of aggregation, the better the storage stability.

[Method of measuring degree of aggregation]
Set 3 different sieve openings (250μm, 149μm, 74μm) in the order of 250μm, middle stage 149μm, lower stage 74μm on the powder tester's shaking table, and put 4g of toner on the upper stage, 1mm vibration Vibrate for 60 seconds in width and measure the weight (g) of toner remaining on each sieve.

The measured toner weight is applied to the following equation to calculate the degree of aggregation (% by weight).
Aggregation degree (% by weight) = a + b + c
a = (weight of toner remaining on upper sieve (g)) / 4 × 100
b = (weight of the toner remaining on the middle screen (g)) / 4 × 100 × (3/5)
c = (weight of toner remaining on lower screen (g)) / 4 × 100 × (1/5)

  From the above results, it can be seen that Examples 1 to 11 are superior in both low temperature fixability and storage stability under high temperature and high humidity as compared with Comparative Examples 1 to 5.

  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 (3)

An electrophotographic toner containing a binder resin, wherein the binder resin contains a crystalline polyester and an amorphous polyester, and the crystal growth rate when the toner is subjected to a heating and holding test. , Formula (A):

[Wherein G is the crystal growth rate (sec ⁻¹ ), G _O is the crystal nucleus number factor (sec ⁻¹ ), E is the activation energy of molecular diffusion (J / mol), R is the gas constant [8.31 (J / mol · K)], Th is the heat holding temperature (K) of the toner, Tg is the glass transition point (K) of the toner in differential scanning calorimetry, K is the nucleation energy (J / mol), and Tc is the differential scanning calorific value. (Shows the maximum peak temperature (K) of toner endotherm in measurement.)
In which the nucleation energy (K) is 150 to 400 J / mol and the crystal nucleus number factor (G ₀ ) is 10 to 1000 sec ⁻¹ .   The toner for electrophotography according to claim 1, wherein the content of the crystalline polyester is 5 to 40% by weight in the binder resin.   The toner for electrophotography according to claim 1 or 2, obtained by a method comprising a step of melt-kneading a toner raw material containing a binder resin and a step of pulverizing the obtained kneaded product.